Kato Yuji

Faculty of Information Science and Technology　Bioengineering and Bioinformatics　BioengineeringAssistant Professor
Last Updated :2025/06/07

■Researcher basic information

Degree

  • Doctor(Engineering), Tohoku University

Researchmap personal page

Home Page URL

J-Global ID

Research Keyword

  • 光CT
  • 光散乱
  • 散乱
  • 中空導波路
  • 後方散乱光
  • 音響光学効果
  • 赤外ファイバー
  • 光生体計測
  • 低コヒーレント干渉法
  • 近赤外
  • 低コヒーレント光干渉法
  • 高分子薄膜
  • センサー
  • 光薄膜
  • 超音波
  • 多重共鳴吸収
  • 超音波変調法
  • 音響光学特性
  • 生体光計測
  • 時間分解解析
  • 近赤外光
  • 生体透視
  • 光拡散
  • 近軸散乱光
  • snake photon
  • 生体計測
  • 誘電体内装中空導波路
  • 医用画像
  • 最小侵襲医療
  • 断層イメージング

Research Field

  • Life sciences, Biomaterials
  • Life sciences, Biomedical engineering
  • Nanotechnology/Materials, Optical engineering and photonics

Educational Organization

■Career

Career

  • Apr. 2019 - Present
    北海道大学大学院情報科学研究院, 助教
  • Apr. 2007 - Mar. 2019
    Hokkaido University, Graduate School of Information Science and Technology, 助教
  • Apr. 2004 - Mar. 2007
    Hokkaido University, Graduate School of Information Science and Technology, 助手
  • Apr. 1998 - Mar. 2004
    Hokkaido University, Graduate School of Engineering, 助手
  • Oct. 1995 - Mar. 1998
    Hokkaido University, School of Engineering, 助手
  • Apr. 1994 - Sep. 1995
    Tohoku University, Faculty of Engineering, 助手

Educational Background

  • Apr. 1989 - Mar. 1994, Tohoku University, Graduate School of Engineering, 電気及通信工学専攻
  • Apr. 1985 - Mar. 1989, Tohoku University, Faculty of Engineering, 通信工学科

Committee Memberships

  • Apr. 2019 - Present
    日本生体医工学会, 代議員, Society
  • Apr. 2017 - Present
    日本生体医工学会北海道支部, 幹事, Society
  • Apr. 2011 - Present
    レーザー学会東北・北海道支部, 幹事, Society
  • Apr. 2017 - Mar. 2023
    電子情報通信学会MEとバイオサイバネティックス研究会, 専門委員, Society
  • Aug. 2012 - Mar. 2015
    日本生体医工学会北海道支部, 幹事, Society
  • Aug. 2005 - Mar. 2007
    電気学会 次世代バイオメディカル・レーザ応用技術調査専門委員会, 委員, Society
  • Oct. 2000 - Sep. 2003
    電気学会 医療のための光応用新技術調査委員会, 幹事補佐, Society

■Research activity information

Papers

Other Activities and Achievements

  • Solution of Nonlinear Inverse Problems with Variation in Propagation of Each Photon for Near-Infrared Optical Tomography Imaging
    加藤祐次, 電気学会研究会資料(Web), MBE-21-035.037.039.041, 2021
  • Solution of Nonlinear Inverse Problems with Variation in Propagation of Each Photon for Near-Infrared Optical Tomography Imaging
    加藤祐次, 電子情報通信学会技術研究報告(Web), 121, 77(MBE2021 6-11), 2021
  • 体動アーチファクトが波長および測定モードの異なる光電容積脈波に与える影響　　　　　　　　　　　　　　　
    松村 健太, 任田 崇吾, 加藤 祐次, 電子情報通信学会技術研究報告(MEとバイオサイバネティックス), 120, 62, 9, 11, Jun. 2020
    (一社)電子情報通信学会, Japanese
  • 体動アーチファクトが波長および測定モードの異なる光電容積脈波に与える影響　　　　　　　　　　　　　　　
    松村 健太, 任田 崇吾, 加藤 祐次, 電子情報通信学会技術研究報告(MEとバイオサイバネティックス), 120, 62, 9, 11, Jun. 2020
    (一社)電子情報通信学会, Japanese
  • ディジタル位相共役光による散乱抑制におけるコヒーレンス長の影響　　　　　　　　　　　　　　　
    任田 崇吾, 加藤 祐次, 清水 孝一, 電子情報通信学会技術研究報告(MEとバイオサイバネティックス), 119, 97, 11, 15, Jun. 2019
    (一社)電子情報通信学会, Japanese
  • 光による生体内部3次元透視イメージングおよび機能イメージングの実現　　　　　　　　　　　　　　　
    清水 孝一, 加藤 祐次, 北間 正崇, 立野 繁之, 福田記念医療技術振興財団情報, 31, 133, 139, Dec. 2018
    (公財)福田記念医療技術振興財団, Japanese
  • Fundamental Study on 3D Reconstruction of Absorbing Structure in Scattering Media
    加藤 祐次, 宮島 文佳, 清水 孝一, レーザー学会研究会報告 = Reports on topical meeting of the Laser Society of Japan, 17, 13, 27, 32, 04 Aug. 2017
    レーザー学会, Japanese
  • 後方散乱光を用いた血中トリグリセリド濃度の非侵襲的計測法 予備的検証　　　　　　　　　　　　　　　
    松村 健太, 加藤 祐次, 飯永 一也, 清水 孝一, 脂質栄養学, 26, 2, 208, 208, Aug. 2017
    日本脂質栄養学会, Japanese
  • 光透視による支台歯マージン形状の検出の試み(第3報)　　　　　　　　　　　　　　　
    上田 康夫, 加藤 祐次, 山口 泰彦, 清水 孝一, 日本補綴歯科学会誌, 9, 特別号, 235, 235, Jun. 2017
    (公社)日本補綴歯科学会, Japanese
  • Fundamental study for scattering suppression in biological tissue using digital phase-conjugate light with intensity modulation
    Sogo Toda, Yuji Kato, Nobuki Kudo, Koichi Shimizu, Proceedings of SPIE - The International Society for Optical Engineering, 10251, 2017
    SPIE, English
  • 光透視による支台歯マージン形状の検出の試み(第3報)
    上田康夫, 加藤祐次, 山口泰彦, 清水孝一, 日本補綴歯科学会誌(Web), 9, 2017
  • Fundamental study to improve accuracy of 3D reconstruction technique using optical transillumination images of animal body
    宮島 文佳, 加藤 祐次, 清水 孝一, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 513, 77, 81, 22 Mar. 2016
    電子情報通信学会, Japanese
  • Fundamental study for transillumination imaging of biological body using digital phase-conjugate optics
    任田 崇吾, 加藤 祐次, 清水 孝一, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 513, 83, 88, 22 Mar. 2016
    電子情報通信学会, Japanese
  • Experimental study to improve transillumination image by depth estimation using light sources of two wavelengths
    岡崎 恵祐, 加藤 祐次, 清水 孝一, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 513, 107, 112, 22 Mar. 2016
    電子情報通信学会, Japanese
  • Fundamental study for measurement of scattering coefficient using backscattered light : For noninvasive measurement of blood triglyceride level
    王 磊, 飯永 一也, 加藤 祐次, 清水 孝一, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 115, 513, 101, 106, 22 Mar. 2016
    電子情報通信学会, Japanese
  • Fundamental Study for Practical Personal Authentication by Transillumination Imaging of Blood Vessels at Wrist
    HIRAKIDA Shoichi, MATSUMURA Kenta, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 114, 514, 29, 33, 16 Mar. 2015
    The personal authentication with blood vessel image of a finger or a palm has been commonly used in many areas. But the blood vessel image of the wrist has not been used for personal authentication. Recently, wristwatch type wearable devices are becoming common, and the personal authentication at the wrist would be very useful. To answer this demand, we have devised a technique to realize the personal authentication using the transillumination image of the blood vessels at the wrist with a watch-type wearable device. In experiments, the transillumination images were obtained at the adult wrists, and the personal authentication was attempted by the relatively simple algorithm that can be easily implemented in a wearable device. Through these analyses, the feasibility of the personal authentication at the wrist with a wearable device was verified., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Fundamental study for reconstruction of in vivo fluorescent tomographic image using orthogonal function system
    SASAKI Hirotaka, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 114, 514, 41, 46, Mar. 2015
    To improve the transcutaneous fluorescent image of an animal body, we derived a point-spread function (PSF) at a cylindrical surface of a diffuse scattering medium. For practical applications, a new CT algorithm was developed. In this technique, an orthogonal function system was used to reconstruct tomographic image. The feasibility of the proposed technique was verified in the simulation and experiments., 一般社団法人電子情報通信学会, Japanese
  • Fundamental study on scattering suppression technique using equation of beam-wave propagation for optical transillumination imaging
    田中 宏幸, 浪田 健, 加藤 祐次, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 114, 514, 35, 40, Mar. 2015
    電子情報通信学会, Japanese
  • Fundamental study for practical application of optical communication through human body
    関 大輔, 浪田 健, 加藤 祐次, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 114, 514, 47, 52, Mar. 2015
    電子情報通信学会, Japanese
  • Attempt for development of optical communication equipment through human body
    SEKI DAISUKE, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI, Transactions of Japanese Society for Medical and Biological Engineering, 53, S176_03, S176_03, 2015
    To realize practical optical communication through human body, an experimental study was conducted using the near-infrared light through a human hand. A wrist-watch type light transmitter was made and the possibility of the optical signal transmission from the wrist to the fingertip was confirmed. A practical light receiver was installed in a door-knob. Fig.1 shows a wearable light transmitter and a door-knob type receiver. The feasibility of the optical data transmission through the adult hand was verified. The optical radiation from the hand was found to be confined in close proximity (within 100 mm range) of the hand. This controllability of radiation guarantees high security in practice., Japanese Society for Medical and Biological Engineering, Japanese
  • Experimental study for depth estimation of absorber with two wavelength light sources
    OKAZAKI KEISUKE, KATO YUJI, SHIMIZU KOICHI, Transactions of Japanese Society for Medical and Biological Engineering, 53, S218_01, S218_01, 2015
    The depth-dependent point spread function (PSF) is useful to improve the transillumination image blurred by the strong scattering in body tissue. We have proposed a technique to estimate the depth of an absorber by the PSF convolution of the images in different wavelengths. To evaluate the effectiveness of this technique, experiments were conducted. An absorber was placed at 2 mm depth in a scattering medium with 40 mm thickness. The proposed technique was applied to the images at 760 nm and 800 nm wavelengths. Fig.1 shows an example of the results. A correlation peak was observed near the given depth of the absorber. In these analyses, the feasibility of the proposed technique was verified., Japanese Society for Medical and Biological Engineering, Japanese
  • Fundamental study for 3D reconstruction using optical transillumination images
    MIYAJIMA FUMIKA, KATO YUJI, SHIMIZU KOICHI, Transactions of Japanese Society for Medical and Biological Engineering, 53, S217_03, S217_03, 2015
    In 3D optical imaging of a living body with near-infrared light, image deterioration caused by scattering effect is a fundamental and serious problem. To solve this problem, we have newly developed a technique to reconstruct a CT image from tranillumination images with scattering suppression. In an experiment, the effectiveness of the developed technique was verified. The cause of the reconstruction error was found to be not from the technique itself but from the artefact of the experiment. Figure 1 shows the cross sectional images of 10 mm∅ perfect absorber in a scattering medium (μ's =1.0 /mm). The size and the position of the absorber were restored correctly using the proposed technique., Japanese Society for Medical and Biological Engineering, Japanese
  • Fundamental study for reconstruction of in vivo tomographic image of fluorescent object using operation of orthogonal functions.
    SASAKI HIROTAKA, NAMITA TAKESHI, KATO YUJI, SIMIZU KOICHI, Transactions of Japanese Society for Medical and Biological Engineering, 53, S216_01, S216_01, 2015
    To improve the transcutaneous fluorescent image of an animal body, we derived a point-spread function (PSF) at a cylindrical surface of a turbid medium. For practical applications, a new CT algorithm was developed. In this technique, an orthogonal function system was used to reconstruct tomographic image. The usefulness of the proposed technique was examined in experiment with tissue- simulated phantom. Figure 1 shows the result of tomographic reconstruction. The internal fluorescent objects, which are hardly seen in Fig. 1(a), became visible by the proposed technique. Through this analysis, the applicability of the proposed technique was verified., Japanese Society for Medical and Biological Engineering, Japanese
  • Optical transillumination imaging of biological body at off-axis area of light beam using equation for beam wave propagation
    TANAKA HIROYUKI, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI, Transactions of Japanese Society for Medical and Biological Engineering, 53, S216_03, S216_03, 2015
    We have analyzed the beam-wave propagation in random media, and applied it to the transillumination imaging using practically useful light-beam illumination. In light-beam illumination, it is difficult to distinguish the absorber in a transillumination image. The effectiveness of proposed scattering suppression was examined when the absorber existed in off-axis area. Fig. 1 shows the result with the absorber in 10 mm depth from the an observation plane and 20 mm from the light axis. Using the proposed technique, we can recognize the absorber in the transillumination image even if we cannot recognize it in the observed image. The effectiveness of the proposed technique was verified., Japanese Society for Medical and Biological Engineering, Japanese
  • Fundamental study for noninvasive in vivo measurement of blood triglyceride level using backscattered light
    WANG LEI, IINAGA KAZUYA, KATO YUJI, SHIMIZU KOICHI, Transactions of Japanese Society for Medical and Biological Engineering, 53, S217_01, S217_01, 2015
    For the diagnosis of postprandial hyperlipidemia, it is necessary to measure the temporal change of the serum triglyceride level by sampling the blood frequently. To solve this problem, we have developed an optical technique to evaluate the scattering property of the blood serum noninvasively. The scattering coefficient can be measured by the spatially resolved measurement of backscattered light with the diffusion approximation for light propagation. However, this approximation is not necessarily valid for the blood. Figure 1 shows the result of the Monte Carlo simulation. It shows that we can estimate the scattering coefficient accurately even with the human blood (μa=0.5/mm)., Japanese Society for Medical and Biological Engineering, Japanese
  • Experimental verification for time-reverse technique in scattering medium using digital phase-conjugate optics
    TODA SOGO, KATO YUJI, SHIMIZU KOICHI, Transactions of Japanese Society for Medical and Biological Engineering, 53, S216_02, S216_02, 2015
    To suppress the scattering of light in a transillumination image, a new imaging technique using time-reverse technique with phase conjugate light has been reported. We have proposed the possibility of biological transillumination imaging using digital phase conjugate light generated with a spatial light modulator. In experiment, we attempted to restore the incident light image from the light passed through a scattering layer. Figure 1 shows the image of the incident light (a) and the observed image (b) through the scattering layer. The feasibility to generate appropriate phase conjugate light was verified as shown in Fig. 1(c)., Japanese Society for Medical and Biological Engineering, Japanese
  • Analysis for nonlinear inversion technique developed to estimate depth-distribution of absorption by spatially resolved backscattering measurement
    Kazuhiro Nishida, Takeshi Namita, Yuji Kato, Koichi Shimizu, OPTICAL TOMOGRAPHY AND SPECTROSCOPY OF TISSUE XI, 9319, 2015, [Peer-reviewed]
    English
  • ビーム光の散乱体内部伝搬式を用いた生体透視における散乱抑制手法の基礎的検討
    TANAKA HIROYUKI, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI, Optics & Photonics Japan講演予稿集(CD-ROM), 2014, ROMBUNNO.6AA7, Oct. 2014
    Japanese, Summary national conference
  • Development of new optical CT for 3D animal imaging using NIR transillumination images
    TRAN Trung Nghia, Yamamoto Kohei, Namita Takeshi, Kato Yuji, Shimzu Koichi, IEICE technical report. ME and bio cybernetics, 114, 79, 71, 76, Jun. 2014
    To realize three-dimensional optical imaging using transillumination images, we developed a novel technique to suppress the scattering effect in a transillumination image and reconstruct a three-dimensional image of the internal light-absorbing structure of animal body from two-dimensional images. The problem of the depth-dependence of PSF was solved by the calculation of the projection image in the filtered back-projection method. The feasibility and the effectiveness of the proposed technique were verified in the experiments with tissue-equivalent phantom and a living mouse. Using the proposed technique, the high-absorption organs such as kidneys and the bottom parts of the liver were reconstructed in a 3D image of mouse abdomen., 一般社団法人電子情報通信学会, English
  • Attempt for optical BAN on human body
    Seki D, Namita T, Kato Y, Shimizu K, 20th Symposium of the International Society on Biotelemetry Proceedings, 29, 31, May 2014
    19–22 May 2022 Kyoto, JapanFundamental study was conducted to apply the optical biotelemetry technique to the body area network (BAN). With this technique, we can expect many advantages over the conventional BAN with electric signal transmission. The bandwidth was evaluated to be 2.80 GHz. The optical signal reached the longer distance in the narrower channel due to the light-guide effect in diffuser. For a prototype of a practical system, an array of LEDs was attached to the wrist area and transmitted light was detected with an avalanche photodiode. The signal transmission (100 kHz, ASK) from the wrist to the fingertips was attained in an adult hand. In the experiment, the following facts were newly found. When the transmission range in the hand exceeds 70 mm, the intensity of radiation from the hand surface became larger than that of the internal propagation through the hand tissue. The transmission range became larger with the lower duty ratio of the optical ASK signal. These results provide useful information for the realization of the optical BAN as an application of optical biotelemetry., [京都大学フィールド科学教育研究センター], English
  • Image improvement of absorbing structure in turbid medium for optical transillumination imaging of biological body
    YAMAMOTO KOHEI, TRAN TRUNG NGHIA, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI, 電子情報通信学会技術研究報告, 113, 499(MBE2013 115-148), 115, 120, 17 Mar. 2014
    To improve near-infrared transillumination images of biological tissue, a new scattering suppression technique was developed. It enables us to apply the point spread function (PSF) derived for light source to the transillumination image of an absorbing structure. The feasibility of the proposed technique was verified in experiment with tissue-equivalent phantom and biological tissue. If we know the depth of the absorber, we can effectively suppress the scattering effect in the image. To apply this technique to an unknown absorber in turbid medium, we also developed the depth estimation technique for the absorbing structure. The effectiveness of the proposed technique was verified in experiments., 一般社団法人電子情報通信学会, Japanese
  • Development of imaging technique for fluorescent object in cylindrical turbid medium : For transcutaneous fluorescent imaging through animal tissue
    OGAWA Daiki, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 113, 499, 121, 126, 10 Mar. 2014
    To improve the transcutaneous fluorescent image of an animal body, we derived a point-spread function (PSF) at a cylindrical surface of a diffuse scattering medium. In this technique, distortion problem of the restored shape was remained. To solve this problem, a new technique was developed. In this technique, the asymmetric 2 dimensional PSF was divided into parts, or the symmetric and asymmetric parts. The feasibility of the proposed technique was verified in the simulation and experiments. The applicability to the biological tissue was also verified., 一般社団法人電子情報通信学会, Japanese
  • Transillumination imaging of blood vessel in human forearm : Application to arteriovenous fistula care in artificial hemodialysis
    Natsume Yuya, Namita Takeshi, Kato Yuji, Kitama Masataka, Shimizu Koichi, IEICE technical report. ME and bio cybernetics, 113, 499, 127, 131, 10 Mar. 2014
    For optical observation of arteriovenous fistula in dialysis treatment, we have developed a transmission image improvement technique using the measured point spread function (PSF) of implanted fluorescent source inside the body. In the experimental study of model phantom, the effectiveness of the proposed technique was confirmed. Then, it was applied to the biological tissue, and its usefulness in practice was verified., 一般社団法人電子情報通信学会, Japanese
  • Attempt to estimate absorption distribution accurately by time-resolved measurement of backscattered light
    OBA Kazuhiro, YOKOYAMA Naoya, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 113, 499, 109, 114, Mar. 2014
    We have developed a technique to estimate the spatial distribution of the absorption coefficient (μ_a) of turbid medium by the time-resolved measurement of backscattered light, and verified its feasibility in simulation and experiments. For accurate estimation of the μ_a distribution, accurate scattering property of the medium is essential. Here, we newly developed a technique to estimate the accurate scattering coefficient (μ_s) by reducing the effect of the absorption heterogeneity. To estimate the μ_a more accurately, we also devised a new technique in which we attach a diffuser plate with known μ_s at the body surface. The feasibility and the usefulness of these techniques were verified in the Monte Carlo simulation., 一般社団法人電子情報通信学会, Japanese
  • 3D reconstruction of internal structure of animal body using near-infrared light
    Tran Trung Nghia, Yamamoto Kohei, Namita Takeshi, Kato Yuji, Shimizu Koichi, BIOMEDICAL APPLICATIONS OF LIGHT SCATTERING VIII, 8952, 2014, [Peer-reviewed]
    English
  • 経皮蛍光透視のための円柱拡散体における散乱抑制手法の改良
    小川大貴, 浪田健, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集(CD-ROM), 2013, ROMBUNNO.14AD8, Nov. 2013
    Japanese, Summary national conference
  • 散乱体内部における吸収係数分布推定のための散乱係数実測法の開発(II)―散乱不均質媒質への適用―
    大場一寛, 横山直弥, 浪田健, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集(CD-ROM), 2013, ROMBUNNO.14AD9, Nov. 2013
    Japanese, Summary national conference
  • 実測点拡がり関数による内シャント透視像復元手法の改善
    夏目裕也, 浪田健, 加藤祐次, 北間正崇, 清水孝一, Optics & Photonics Japan講演予稿集(CD-ROM), 2013, ROMBUNNO.12AA2, Nov. 2013
    Japanese, Summary national conference
  • 生体透視イメージングのための点拡がり関数による吸光像改善の試み
    山本航平, 田中宏幸, NGHIA Tran Trung, 浪田健, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集(CD-ROM), 2013, ROMBUNNO.14PD1, Nov. 2013
    Japanese, Summary national conference
  • Basic study for optical communication through human body
    Seki Daisuke, Namita Takeshi, Kato Yuji, Shimizu Koichi, Proceedings of the Society Conference of IEICE, 2013, 2, "S, 147"-"S-148", Sep. 2013
    一般社団法人電子情報通信学会, Japanese
  • Attempt for optical data transmission through human palm
    AKIYAMA JUNKICHI, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI, 電子情報通信学会技術研究報告, 112, 479(MBE2012 88-129), 179, 184, 13 Mar. 2013
    To realize practical optical communication through human body, an experimental study was conducted on the near-infrared light propagation through model phantoms and a human hand. In a backscattering configuration, the optical data transmission over 200 mm distance was possible. Using a practically compact equipment, the optical data transmission from the wrist to fingertips was attained. It was found that the light attenuation was lower along a narrow diffusing object than the object with large scattering volume. These results suggested the feasibility of the optical communication through a human palm., 一般社団法人電子情報通信学会, Japanese
  • Fundamental study for thickness estimation of fluorescent object in scattering medium using dual wavelength excitation
    OBATA KYOHEI, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI, 電子情報通信学会技術研究報告, 112, 479(MBE2012 88-129), 133, 138, 13 Mar. 2013
    A technique was newly developed to estimate the thickness of a fluorescent object in a turbid medium, such as an animal body. In this technique. we estimate the thickness from the different in the fluorescent intensity caused by the difference in the absorption of excitation light between two wavelengths. We analyzed the relation between the thickness of a fluorescent object and the intensity ratio of the fluorescent light, and confirmed the validity of this principle. Using this principle, we attempted to estimate the thickness and the depth of a fluorescent object simultaneously. We found that we can make better estimation for both parameters by estimating the depth first. In an experiment, we estimated the depth and the thickness of the fluorescent object in a tissue equivalent phantom. With the depth. we obtained a point spread function for image restoration. Using the restored image and the estimated depth, we could construct three dimensional image of a fluorescent object in a turbid medium., 一般社団法人電子情報通信学会, Japanese
  • Development of technique for improvement of optical transillumination images using equation of beam wave propagation
    OKUYAMA Yuki, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 112, 479, 121, 126, 06 Mar. 2013
    To realize the practical transillumination imaging with beam-wave incidence. we had derived the equation of beam-wave propagation in a turbid medium theoretically, and formulated the procedure of image processing. The validity and effectiveness of the proposed technique was verified in experiment. The effectiveness of our technique to correct the deviation of the blurred image caused by the inhomogeneity of the incident light and the applicability of the proposed technique to the biological tissue was also examined., 一般社団法人電子情報通信学会, Japanese
  • Depth estimation and image improvement of fluorescent objects in turbid medium with unknown optical coefficients
    XIA Jiao, NAMITA Takeshi, Kato Yuji, Shimizu Koichi, IEICE technical report. ME and bio cybernetics, 112, 479, 127, 132, 06 Mar. 2013
    To obtain a clear image in transcutaneous fluorescent imaging, we have newly developed a technique to simultaneously estimate the depth and optical coefficients which have to be known a priori to improve fluorescent images. The feasibility of the proposed technique was verified in both numerical analysis and experiment. It was demonstrated that we could restore the blurred fluorescent images well with a point spread function (PSF), which is dependent on the estimated depth and optical coefficients. Finally, the applicability of the proposed technique to the biological body was verified in the experiment with a biological sample tissue., 一般社団法人電子情報通信学会, Japanese
  • Fundamental study on CT imaging of tissue oxygen saturation by time-resolved measurement of backscattered light
    MORIMOTO Takuro, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 112, 479, 139, 144, 06 Mar. 2013
    To realize the tissue oxygen saturation imaging by time-resolved measurement of backscattered light, appropriate wavelengths have been chosen from the absorption spectrum of hemoglobin. For the precise estimation in the medium with spatially inhomogeneous scattering coefficient (μs),a new technique was developed to estimate the tissue oxygen saturation using the Us estimation technique in the same measurement scheme. The effectiveness of the proposed technique was verified in the simulation with the layer model that simulates spatially inhomogeneous scattering and absorption coefficients., 一般社団法人電子情報通信学会, Japanese
  • Experimental study for imaging through scattering medium by time reversal method using phase conjugate optics
    YOKOTA Shun, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 112, 479, 173, 177, 06 Mar. 2013
    The absorption at a specific position inside a turbid medium can be measured by back-propagating the scattered light using phase conjugate light and focused ultrasonic modulation. With the view toward clear imaging through turbid medium, we constructed an experimental system to make the back-propagation of scattered light possible using phase conjugate light. We confirmed the fundamental performance for the extraction of a localized area in turbid medium. In experiment, we attempted to restore the incident light from the scattered light by back-propagating the scattering process using phase conjugate light., 一般社団法人電子情報通信学会, Japanese
  • Reconstruction technique for 3 dimensional structure in shallow layer of turbid medium using optical transillumination images : Attempt for reconstruction with limited view angle
    Matsuura Taiki, Namita Takeshi, Kato Yuji, Shimizu Koichi, IEICE technical report. ME and bio cybernetics, 112, 479, 167, 172, Mar. 2013
    For the 3D non-invasive imaging of shallow regions of a human body, we have developed a new technique to reconstruct the absorbing structure from optical transillumination images obtained in limited view angle. The effectiveness of the proposed technique was verified in the experiment using the model phantom that simulates the veins in the human forearm. Further, we extended the technique so that we can apply it to the turbid medium with unknown internal structure and the usefulness was verified. The applicability of the proposed technique to the biological tissue was also examined., 一般社団法人電子情報通信学会, Japanese
  • Fundamental study for optical BAN
    Shimizu, K., Namita, T., Kato, Y., Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST, 61, 173, 178, 2013, [Peer-reviewed]
    Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST, English
  • Feasibility Study for Optical BAN
    Junkichi Akiyama, Daisuke Seki, Takeshi Namita, Yuji Kato, Koichi Shimizu, 2013 7TH INTERNATIONAL SYMPOSIUM ON MEDICAL INFORMATION AND COMMUNICATION TECHNOLOGY (ISMICT), 14, 17, 2013, [Peer-reviewed]
    English
  • New nonlinear inversion technique for depth distribution of absorption using spatially resolved backscattering measurement
    Kazuhiro Nishida, Takeshi Namita, Yuji Kato, Koichi Shimizu, OPTICAL TOMOGRAPHY AND SPECTROSCOPY OF TISSUE X, 8578, 2013, [Peer-reviewed]
    English
  • New Reconstruction Technique for 3 Dimensional Structure in Shallow Layer of Turbid Medium using Optical Transillumination Images - Attempt for Reconstruction with Limited View Angle -
    Taiki Matsuura, Takeshi Namita, Yuji Kato, Koichi Shimizu, 2013 35TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC), 1795, 1798, 2013, [Peer-reviewed]
    English
  • Application of Fluorescent PSF for 3D Reconstruction of Absorbing Structure using Slab Transillumination Images
    Tran Trung Nghia, Takeshi Namita, Yuji Kato, Koichi Shimizu, 2013 35TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC), 2644, 2647, 2013, [Peer-reviewed]
    English
  • Depth estimation and image improvement of fluorescent objects in scattering medium with unknown optical parameters
    Jiao Xia, Takeshi Namita, Yuji Kato, Koichi Shimizu, Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS, 2648, 2651, 2013, [Peer-reviewed]
    IEEE, English
  • 後方散乱光による高確度吸収係数分布推定法の多層構造への適用
    加藤祐次, 浪田健, 清水孝一, 電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM), 2012, ROMBUNNO.134, Oct. 2012
    Japanese, Summary national conference
  • 多波長を用いた生体機能の断層イメージングの試み―断層イメージングのための波長選定―
    森本拓朗, 浪田健, 加藤祐次, 清水孝一, 生体医工学, 50, 4, 358, Aug. 2012
    Japanese, Summary national conference
  • Improvement of transillumination image of blood vessels using multiple wavelengths of light
    西田 浩平, 浪田 健, 加藤 祐次, 電子情報通信学会技術研究報告 : 信学技報, 111, 482, 13, 18, Mar. 2012
    電子情報通信学会, Japanese
  • Fundamental study for 3D reconstruction of fluorescent object in biological body
    TOZAWA Eiji, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 111, 482, 123, 128, Mar. 2012
    To improve the transcutaneous fluorescent image of an animal body, we derived the depth dependent point-spread function (PSF) for the fluorescent object in scattering medium and demonstrated scattering suppression technique using the depth dependent PSF. We have newly developed a technique to reconstruct 3-dimentional image of a fluorescent object using this scattering suppression technique and the common 2-dimentional tomography technique. The validity of the proposed technique was verified in simulation and experiment with model phantom. A PSF at a cylindrical surface of a diffuse scattering medium was also newly developed. The validity of this PSF and the applicability of this PSF to reconstruct the 3-dimensional image were verified in experiments., 一般社団法人電子情報通信学会, Japanese
  • Development of absorption distribution estimation technique using backscattered light with scattering characteristic measurement
    OTANI Masafumi, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 111, 482, 1, 6, Mar. 2012
    We have developed a technique to estimate the absorption coefficient (μ_a) of turbid medium by the time-resolved measurement of backscattered light, and verified its feasibility in simulation and experiments. For accurate estimation of the absorption distribution in a diffuse scattering medium, accurate scattering property of the medium is essential. Here, we newly developed a technique to obtain the important parameters required for the absorption estimation by measuring the scattering property of the medium using backscattered light. The results using the proposed technique were compared with those using the former technique in which the scattering property of the medium was assumed to be known and homogeneous. Through these simulations, the feasibility and the effectiveness of the proposed technique were verified., 一般社団法人電子情報通信学会, Japanese
  • Development of size distribution estimation technique for small, dense LDL in dynamic light scattering measurement
    WEI Dingding, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 111, 482, 7, 12, Mar. 2012
    A dynamic light scattering (DLS) technique has been applied to quantify the amount of the small dense low-density lipoprotein (sdLDL) which is clinically significant for coronary diseases. A technique to obtain the size distribution of LDL particles in the DLS measurement was newly developed. This technique is applicable even to the relatively narrow size-range (20-30 nm) of sdLDL, and vulnerable against the random noise in the autocorrelation function of DLS. The effectiveness of the proposed technique was verified in the computer simulation and in the experiment with latex spheres and LDL particles., 一般社団法人電子情報通信学会, English
  • Development of restoration technique for biological absorption image in turbid medium using point spread function
    TAKAHASHI Hiroki, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 111, 482, 19, 24, Mar. 2012
    To improve NIR transillumination images of animal body, the application of the point spread function (PSF) derived for fluorescent source inside the body was attempted. Through experimental study, the applicability was demonstrated. In addition, the step-wise deconvolution technique using partial PSF's was newly devised to solve the problem of instability in the deconvolution using the wide PSF for deep seated structure under the skin. In simulation and experiments with a model phantom, the effectiveness of the proposed technique was confirmed. Then, it was applied to the human body, and its usefulness in practice was verified., 一般社団法人電子情報通信学会, Japanese
  • Development of accurate estimation technique for absorption distribution by time-resolved measurement of backscattered light
    SUGIYAMA Keita, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 111, 482, 25, 30, Mar. 2012
    The absorption distribution along the depth direction in a turbid medium can be estimated in the time-resoloved measurement. For accurate estimation of the absorption distribution in scattering medium, a new technique which is applicable even to large inhomogeneity was developed. In this technique, the difference of the propagation path for every photon was considered. The effectiveness of the proposed technique was verified in computer simulation. To examine the applicability of the proposed technique, Monte Carlo simulation was conducted with the model of the human head. Through this analysis, the applicability of the proposed technique to a human body was verified., 一般社団法人電子情報通信学会, Japanese
  • Arteriovenous discrimination by spectroscopic analysis of transillumination images
    MATSUDA Yasushi, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 111, 482, 151, 156, Mar. 2012
    We have shown the possibility of transillumination imaging of the arteries in the adult forearm as well as the veins. Using the change of absorption spectra of blood hemoglobin, we can expect to discriminate the arteries from the veins in the transillumination images. First, the validity of the proposed principle was confirmed in the measurement of the contrast change with the wavelength of light. We have developed a practical technique to visualize blood vessels with arteriovenous discrimination. The proposed technique was applied to the subjects with different ages and gender. The feasibility of transcutaneous imaging with arteriovenous discrimination was verified in experiments., 一般社団法人電子情報通信学会, Japanese
  • 手掌を介した光データ通信の試み
    秋山潤吉, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 51st, 2012
  • 光透視像を用いた散乱体表層構造の3次元再構成―限定方位透視像からの再構成の試み―
    松浦太紀, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 51st, ROMBUNNO.O3-09-2, 2012
    Japanese, Summary national conference
  • 後方散乱光時間分解計測による高確度吸光度分布推定法(III)―生体への適用可能性の検証―
    杉山慶多, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 51st, ROMBUNNO.O3-10-3, 2012
    Japanese, Summary national conference
  • 複数波長励起による散乱体中の蛍光体厚さ推定のための基礎的検討
    小幡恭平, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 51st, ROMBUNNO.O3-10-5, 2012
    Japanese, Summary national conference
  • 多波長光源による散乱体内部蛍光体の深さと厚さ同時推定の試み
    小幡恭平, 浪田健, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集(CD-ROM), 2012, ROMBUNNO.24PA9, 2012
    Japanese, Summary national conference
  • ビーム光の散乱体内部伝播式による生体透視像改善の試み
    奥山雄基, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 51st, ROMBUNNO.O3-09-4, 2012
    Japanese, Summary national conference
  • 血管透視像の分光解析による動静脈判別の試み(III)―複数被験者による実用性の検証―
    松田康志, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 51st, ROMBUNNO.O3-10-1, 2012
    Japanese, Summary national conference
  • 点拡がり関数を用いた生体透視像改善のための基礎的検討(III)―実用的条件下での光源PSF適用可能性の検証―
    高橋博樹, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 51st, ROMBUNNO.O3-09-3, 2012
    Japanese, Summary national conference
  • ビーム光の散乱体内部伝搬式による生体透視像改善の試み(II)―提案手法の特性評価―
    奥山雄基, 浪田健, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集(CD-ROM), 2012, ROMBUNNO.24PA12, 2012
    Japanese, Summary national conference
  • 多波長散乱計測による組織酸素飽和度断層イメージングの試み(II)―散乱不均質媒質における適用可能性の検証―
    森本拓朗, 浪田健, 大場一寛, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集(CD-ROM), 2012, ROMBUNNO.24PA14, 2012
    Japanese, Summary national conference
  • Development of scattering suppression technique for reconstruction of absorption structure using point spread function for cylindrical scattering medium
    NGHIA Tran Trung, YAMAMOTO Kohei, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, Optics & Photonics Japan講演予稿集(CD-ROM), 2012, ROMBUNNO.23PA6, 2012
    English, Summary national conference
  • Development of size distribution estimation technique for small, dense LDL in dynamic light scattering measurement:III-Verification of effectiveness in experiment-
    WEI Dingding, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, 日本生体医工学会大会プログラム・論文集(CD-ROM), 51st, ROMBUNNO.O3-10-2, 2012
    English, Summary national conference
  • Development of simultaneous observation system for transillumination imaging of blood vessels using visible and near-infrared light
    TOBISAWA Naoya, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 110, 460, 147, 152, Feb. 2011
    To assist vascular injection, we have developed a simultaneous observation system using a body surface image and a transillumination image of blood vessels. Light source was devised to make homogeneous, wide-area and low-leak illumination possible. Using the developed system, we could obtain the transillumination images in all part of the adult forearm with as much as 67 mm thickness. In addition to the superficial veins, we could visualize the arteries in the forearm. Its usefulness was examined in the simulation of injection with a phantom of the human forearm., 一般社団法人電子情報通信学会, Japanese
  • Reconstruction of 3-dimensional structure in scattering medium from transillumination images using scattering suppression technique
    SHIMANO Moto, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 110, 460, 153, 158, Feb. 2011
    To see through a turbid medium, a technique was developed to reconstruct a three-dimensional structure inside the medium. Clear transillumination images were obtained with a scattering suppression technique in which the weakly scattered light component can be extracted from the strongly diffused light. The possibility of the proposed technique was examined in the experiment using the turbid medium with known internal structure. Through the experimental analysis, the feasibility of the proposed technique and the effectiveness of the scattering suppression were verified., 一般社団法人電子情報通信学会, Japanese
  • Reliable scattering coefficient estimation against absorption inhomogeneity by time-resolved measurement of backscattered light
    Takeshi Namita, Masayuki Kawashima, Yuji Kato, Koichi Shiniizu, 2011 Int. Quantum Electron. Conf., IQEC 2011 and Conf. Lasers and Electro-Optics, CLEO Pacific Rim 2011 Incorporating the Australasian Conf. Optics, Lasers and Spectroscopy and the Australian Conf., 1696, 1698, 2011
    English, Summary national conference
  • 点拡がり関数を用いた生体透視像改善のための基礎的検討-蛍光PSF応用の試み-
    高橋博樹, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 50th, 2011
  • 点拡がり関数を用いた生体透視像改善のための基礎的検討(II)―深部吸光構造への適用可能性―
    高橋博樹, 浪田健, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集(CD-ROM), 2011, ROMBUNNO.29PD12, 2011
    Japanese, Summary national conference
  • 複数の励起光源セットによる蛍光体深さ推定の試み:II―実験的検証と新たな応用可能性―
    XIA Jiao, 浪田健, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集(CD-ROM), 2011, ROMBUNNO.29PD11, 2011
    Japanese, Summary national conference
  • 後方散乱光計測による散乱不均質媒質にも適用可能な吸収分布推定法の開発
    大谷真史, 浪田健, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集(CD-ROM), 2011, ROMBUNNO.29PD3, 2011
    Japanese, Summary national conference
  • 水との相互作用を考慮した近赤外分光法による生体成分の定量分析
    西田和弘, 浪田健, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集(CD-ROM), 2011, ROMBUNNO.29AD4, 2011
    Japanese, Summary national conference
  • 多波長光源を用いた静脈透視画像の改善(II)―複数被験者における有効性の検証―
    西田浩平, 浪田健, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集(CD-ROM), 2011, ROMBUNNO.30AF7, 2011
    Japanese, Summary national conference
  • 血管透視像の分光解析による動静脈判別の試み(II)―判別原理の実験的検証―
    松田康志, 飛澤直哉, 浪田健, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集(CD-ROM), 2011, ROMBUNNO.29PD9, 2011
    Japanese, Summary national conference
  • 散乱体内部蛍光体の三次元像再構成法の開発
    戸澤英二, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 50th, ROMBUNNO.O3-6-6, 2011
    Japanese, Summary national conference
  • 散乱抑制による光透視像からの散乱体内部3次元構造再構成(II)―局部吸収体の3次元再構成―
    嶋野心, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 50th, ROMBUNNO.O3-6-4, 2011
    Japanese, Summary national conference
  • 体表像と血管透視像による静脈注射支援システムの検証
    飛澤直哉, 松田康志, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 50th, ROMBUNNO.O3-6-5, 2011
    Japanese, Summary national conference
  • 多波長光源を用いた静脈透視画像改善
    西田浩平, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 50th, ROMBUNNO.O3-7-3, 2011
    Japanese, Summary national conference
  • 多点励起による蛍光体深さ推定の試み―光学定数が変化したときの深さ較正曲線の導出―
    XIA Jiao, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 50th, ROMBUNNO.O3-7-2, 2011
    Japanese, Summary national conference
  • 散乱抑制による光透視像からの散乱体内部3次元構造再構成
    嶋野心, 浪田健, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集, 2010, 324, 325, Nov. 2010
    Japanese, Summary national conference
  • 体表像と血管透視像の同時観察システムの開発
    飛澤直哉, 浪田健, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集, 2010, 326, 327, Nov. 2010
    Japanese, Summary national conference
  • Development and application of scattering suppression technique using weakly diffused light for transillumination imaging of biological body
    KAKINUMA Hiroyuki, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 109, 460, 95, 100, 02 Mar. 2010
    To realize a technique applicable to thicker body, the effectiveness of a transillumination imaging using weakly diffused light was examined in experiments. The possibility to extract the weakly diffused component from strongly diffused light was clarified in spatial and temporal analyses. Apparent improvement of transillumination images was demonstrated with a model phantom and a biological specimen. A technique to estimate the depth of an absorber in disuse medium was newly developed. The stability of the depth estimation technique and its applicability to animal tissue were verified in e..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Fundamental study for realization of data transmission using scattered light in human body
    KAKITA Shun, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 109, 460, 101, 106, 02 Mar. 2010
    To realize new optical communication through a human body, the feasibility of data transmission using diffusely scattered light in a human body was examined. Transmissible range of optical data in the human maniphalanx was measured. The data transmission through about 100 mm distance was possible with our experimental system. To overcome the problems of the noises, multipath transmission, and the cut of transmission paths, the space diversity (SD) method was applied to stabilize the data communication. In simulation, the effectiveness of the SD method was confirmed. For the SD method, diffe..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Depth estimation and image improvement of fluorescent objects in scattering medium by reflection-type measurement with two light sources
    SHIMIZU Atsushi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 109, 460, 133, 138, 02 Mar. 2010
    Transcutaneous fluorescent images are deteriorated due to the optical scattering of body tissues. Using a depth-depending PSF(point spread function), this effect can be suppressed effectively. We have newly developed a technique to estimate the depth of a fluorescent object in a scattering medium with two light sources. The effectiveness of this technique was confirmed in the experiment with a simple fluorescent object in a scattering medium. Then the proposed technique was improved so as to be applicable to the case of multiple fluorescent objects at different depths. Using model phantoms ..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Development of practical transcutaneous fluorescent imaging technique using measured PSF
    TAKESHITA Yusuke, KATO Yuji, DATE Hiroyuki, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 109, 460, 139, 143, 02 Mar. 2010
    A new technique was developed to realize the fluorescence angiography based on the image restoration with point-spread function (PSF). In this technique, the PSF can be obtained using a fluorescence-marked stent placed in a blood vessel. A clear image of the blood vessel can be restored by deconvolving the blurred transcutaneous image with measured PSF. In simulation, the feasibility of the basic idea was confirmed. In the experiments with tissue phantoms, the effectiveness of the proposed technique was verified. Those results suggest the feasibility of the repetitive examination of vessel ..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Development of estimation technique for tissue oxygen saturation distribution by time-resolved measurement of backscattered light using multi-wavelength light
    YOSHIMURA Hitoshi, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 109, 460, 89, 94, Mar. 2010
    To realize functional imaging by time-resolved measurement of backscattered light, a technique has been developed to estimate the spatial distribution of tissue oxygen saturation. In theoretical analysis on the estimation error, the measurement conditions to suppress the error were clarified. The effectiveness of the proposed technique was verified in the Monte Carlo simulation with the three-layer model that simulates the hemoglobin concentrations of the cerebral gray matter and the thigh muscle. The noise tolerance of the proposed technique in solving an inverse problem was evaluated. In ..., 一般社団法人電子情報通信学会, Japanese
  • Characteristic analysis of optical backscattering enhancement through time-resolved measurements of near-infrared light
    CHIKAHISA Tomoya, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report, 109, 460, 127, 132, Mar. 2010
    The possibility of new biological measurement by time resolved analysis of the optical backscattering enhancement was pursued. Through simulation analysis for various optical parameter changes, the extinction time of the enhancement peak was selected as an index to evaluate the scattering property of the turbid medium such as an animal tissue. The effectiveness of this index was verified in experiments. The range of measurable depth in a scattering medium was analyzed. The results with our experimental system suggested that we can measure the scattering coefficient up to 5 mm depth from the surface of the biological body. The feasibility of imaging the spatial distribution of a scattering coefficient using the extinction time of the enhancement peak was verified in experiments., 一般社団法人電子情報通信学会, Japanese
  • Development of measurement techniques for scattering and absorption coefficients in diffuse scattering medium : For optical transillumination imaging of biological body
    SHIMIZU Koichi, NAMITA Takeshi, KATO Yuji, 電気学会研究会資料. IM, 計測研究会, 2010, 1, 33, 38, Feb. 2010
    Japanese
  • Feasibility of scattering coefficient imaging by time-resolved measurement of NIR backscattering enhancement
    CHIKAHISA Tomoya, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, 日本生体医工学会大会プログラム・論文集(CD-ROM), 49th, 2010
  • Experimental verification for scattering coefficient estimation by time-resolved measurement of backscattered light (III)-Attempt for application to biological tissue-
    KAWASHIMA Masayuki, NAMITA Takeshi, OTANI Masafumi, KATO Yuji, SHIMIZU Koichi, 日本生体医工学会大会プログラム・論文集(CD-ROM), 49th, 2010
  • Biological applicability of estimation technique to tissue oxygen saturation distribution by time-resolved measurement of backscattered light
    YOSHIMURA Hitoshi, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, 日本生体医工学会大会プログラム・論文集(CD-ROM), 49th, 2010
  • Estimation of small dense LDL fraction using autocorrelation function of dynamic light scattering II:-Derivation of analytical solution for widely overlapped distribution components-
    TRIRONGJITMOAH Suchin, SAKURAI Toshihiro, NISHIBATA Yuka, NAMITA Takeshi, KATO Yuji, IINAGA Kazuya, CHIBA Hitoshi, SHIMIZU Koichi, 日本生体医工学会大会プログラム・論文集(CD-ROM), 49th, ROMBUNNO.PS3-5-1, 2010
    English, Summary national conference
  • Experimental verification for scattering coefficient estimation by time-resolved measurement of backscattered light
    KAWASHIMA Masayuki, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report, 109, 406, 97, 102, Jan. 2010
    We developed a technique to estimate the reduced scattering coefficient (μ_s') of turbid medium by the time-resolved measurement of backscattered light, and verified its feasibility in simulation. Here, we examined the accuracy and the characteristics of the proposed technique in experiments. The estimated values agreed well with those measured by a conventional technique and with those reported by references. The effect of absorption inhomogeneity on μ_s' estimation was investigated. The term that represents the estimation error was successfully separated in the equation of μ_s' estimation. In an experimental analysis, it was confirmed that the proposed technique is less affected by the μ_a-inhomogeneity and more practical than conventional techniques., 一般社団法人電子情報通信学会, Japanese
  • Attempt for improvement of transcutaneous fluorescent image by measured PSF
    TAKESHITA YUSUKE, KATO YUJI, DATE HIROYUKI, SHIMIZU KOICHI, Optics & Photonics Japan講演予稿集, 2009, 52-53, 24 Nov. 2009
    Japanese
  • Image improvement of multi-fluorescent objects in scattering medium by reflection-type measurement with two light sources
    SHIMIZU ATSUSHI, KATO YUJI, SHIMIZU KOICHI, Optics & Photonics Japan講演予稿集, 2009, 54-55, 24 Nov. 2009
    Japanese
  • Development of scattering suppression technique using weakly diffused light for transillumination imaging of biological body (II)-Progress for depth-estimation of absorbing object-
    KAKINUMA HIROYUKI, TAKAGI KAZUTO, KATO YUJI, SHIMIZU KOICHI, Optics & Photonics Japan講演予稿集, 2009, 48-49, 24 Nov. 2009
    Japanese
  • Development of technique to estimate small dense LDL fraction by dynamic light scattering: II
    TRIRONGJITMOAH Suchin, SAKURAI Toshihiro, NISHIBATA Yuka, NAMITA Takeshi, KATO Yuji, IINAGA Kazuya, CHIBA Hitoshi, SHIMIZU Koichi, Optics & Photonics Japan講演予稿集, 2009, 64, 65, Nov. 2009
    English, Summary national conference
  • Evaluation of CT imaging technique by time-resolved measurement of backscattered light (III)-Effect of inhomogeneous scattering property on estimation of absorption distribution-
    NAMITA TAKESHI, OTANI MASAFUMI, KAWASHIMA MASAYUKI, KATO YUJI, SHIMIZU KOICHI, Optics & Photonics Japan講演予稿集, 2009, 62, 63, Nov. 2009
    Japanese, Summary national conference
  • Experimental verification for scattering coefficient estimation by time-resolved measurement of backscattered light (II)-Comparison with scattering coefficient measurement by common technique-
    KAWASHIMA MASAYUKI, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI, Optics & Photonics Japan講演予稿集, 2009, 50, 51, Nov. 2009
    Japanese, Summary national conference
  • 動的光散乱によるLDLの計測 sdLDLの定量評価をめざして(Application of Dynamic Light Scattering to LDL Measurement: Attempt for quantitative evaluation of small dense LDL)
    トライロンジットモア・スチン, 櫻井 俊宏, 西端 友香, 浪田 健, 加藤 祐次, 飯永 一也, 千葉 仁志, 清水 孝一, 電子情報通信学会技術研究報告(MEとバイオサイバネティックス), 109, 106, 23, 28, Jun. 2009
    (一社)電子情報通信学会, English
  • Application of Dynamic Light Scattering to LDL Measurement : Attempt for quantitative evaluation of small dense LDL
    TRIRONGJITMOAH Suchin, SAKURAI Toshihiro, NISHIBATA Yuka, NAMITA Takeshi, KATO Yuji, IINAGA Kazuya, CHIBA Hitoshi, SHIMIZU Koichi, 電気学会研究会資料. MBE, 医用・生体工学研究会, 2009, 71, 23, 28, Jun. 2009
    English
  • 動的光散乱によるsmall dense LDLの割合推定の試み
    トライロンジットモア スチン, 浪田健, 西端友香, 櫻井俊宏, 加藤祐次, 飯永一也, 千葉仁志, 清水孝一, 生体医工学, 47, 3, 321, 321, Jun. 2009
    (公社)日本生体医工学会, Japanese, Summary national conference
  • Basic Study on Optical Tomographic Imaging for Small Experimental Animals (II)-High-Resolution Imaging for Optical Absorption Change-
    TANAKA YOSHINORI, KITAMA MASATAKA, ARISAWA JUNJI, TAKAGI KAZUTO, KATO YUJI, SHIMIZU KOICHI, 北海道工業大学研究紀要, 37, 271, 277, 24 Mar. 2009
    北海道工業大学, Japanese
  • Basic study for scattering and absorption measurement of diffuse medium by Doppler optical coherence tomography
    NEMOTO Tomoyuki, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 108, 479, 133, 137, 04 Mar. 2009
    For the measurement of the functional information in a biological body such as the oxygenation of the blood in the blood vessel in vivo, a technique was developed to measure scattering and absorption characteristic of flowing scattering medium by Doppler OCT principle. The intensity of the Doppler signal caused by the blood flow is measured in the spatially resolved measurement of OCT. We can estimate the optical characteristics of the blood from the attenuation of this signal with the distance in the depth direction. The concentration of an absorbing component in the blood can be also esti..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Fundamental study for next generation vein-authentication by reflection-type transillumination image of blood vessels
    AMAI Kenji, TAKAGI Kazuto, KATO Yuji, AMANO Kazuhiko, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 108, 479, 127, 132, 04 Mar. 2009
    To realize next-generation actionless personal authentication, fundamental study was conducted to develop a wearable sensor for vein authentication. A transillumination image of blood vessels was obtained in a circular light source of epi-illumination. The major inhomogeneity over the total view area could be compensated by the attenuation filter designed from the diffusion theory. The effect of discrete light sources and the image processing for local inhomogeneity were investigated. Through this study, we could obtain the transillumination image of sufficient quality for vein authentication., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Attempt for reconstruction of tomographic image by transcutaneous fluorescent imaging
    SHIDA Genki, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 108, 479, 89, 93, 04 Mar. 2009
    A new technique was developed to obtain the CT image for the fluorescent material in a biological body. Fluorescent images blurred by scattering are obtained at the body surface from all the circumferential directions. Deblurred images are restored using the depth-dependant point spread function. A CT image can be reconstructed using the deblurred images by the filtered back projection method. The feasibility and the effectiveness of the proposed technique were verified in the simulation and the experiments with a model phantom and a biological sample., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Fundamental study on optical tomographic imaging for small experimental animals
    TANAKA Yoshinori, KITAMA Masataka, ARISAWA Junji, TAKAGI Kazuto, KATO Yuji, SHIMIZU Koichi, IEICE technical report, 2009, 1, 27, 32, 23 Jan. 2009
    A fundamental study was conducted on the tomographic imaging using near-axis scattered light for small experimental animals. We velified the feasibility of CT imaging by extracting the near-axis scattered light using the optical difference principle. We showed that the quantitative CT imaging of absorption distribution is possible. The spatial resolution of CT images obtained with our experimental system was evaluated as about 1mm., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Estimation of small dense LDL fraction using auto-correlation function of dynamic light scattering
    TRIRONGJITMOAH Suchin, NAMITA Takeshi, SAKURAI Toshihiro, KATO Yuji, IINAGA Kazuya, CHIBA Hitoshi, SHIMIZU Koichi, 日本生体医工学会大会プログラム・論文集(CD-ROM), 48th, 2009
  • 生体光散乱における後方散乱強調現象の時間特性解析
    近久智哉, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 48th, ROMBUNNO.23AMP1-1-7, 2009
    Japanese, Summary national conference
  • 後方散乱光時間分解計測による体内吸収体の厚み推定
    浪田健, 川島雅之, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 48th, ROMBUNNO.23AMP1-1-6, 2009
    Japanese, Summary national conference
  • 後方散乱光時間分解波形からの生体内散乱係数計測法の考案
    清水孝一, 金澤瑠維, 川島雅之, 浪田健, 加藤祐次, 電気学会基礎・材料・共通部門大会講演論文集(CD-ROM), 2008, ROMBUNNO.XIX-3, Aug. 2008
    Japanese, Summary national conference
  • Depth-selective imaging of scattering medium using multiple circular light sources
    Goto Yasuo, Kato Yuji, Shimizu Koichi, IEICE technical report. ME and bio cybernetics, 107, 541, 49, 52, 06 Mar. 2008
    To realize a simple depth-selective imaging of diffuse medium, a new technique was developed that uses multiple circular light sources, an imaging device, and image subtraction process. If the position of a light source on the body surface changes, the propagation region of scattered light in the body becomes different. The proposed technique detects this difference by image subtraction. In the simulation based on the diffusion theory, the effectiveness of the technique was confirmed. Using a model phantom, the applicability of the technique to mammalian tissue was verified. The possibility..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Feasibility of transcutaneous data transmission using scattered light
    SAITO Toshihide, KAKITA Shun, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 107, 541, 57, 60, 06 Mar. 2008
    For advanced data communication from implanted device, a fundamental study was conducted on the information transmission inside a biological body using light. To examine the effect of strong optical scattering inside the body, the frequency bandwidth for data transmission was evaluated. In the experiment using meat, the possibility of the transmission up to 100MHz was confirmed. To expand the bandwidth, various signal processing techniques were compared. With the linear equalizing process, we can transmit an 800MHz square wave signal. It was confirmed that 900Mcps transmission becomes possi..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Time-resolved analysis of optical backscattering enhancement
    KUBO Yoshihiro, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 107, 541, 53, 56, Mar. 2008
    The backscattering enhancement has been studied with continuous light. We attempted the time-resolved analysis for this phenomenon. It was newly found that the width of the backscattering enhancement peak becomes narrower as time goes in the rising time of the time-resolved backscattering pulse from diffuse scattering medium. In the falling time of the backscattering pulse, the backscattering enhancement peak disappears as the time goes. We can evaluate the multiple-scattering characteristics of a sample by measuring the extinction time of the peak. Using latex beads and the Intralipid susp..., 一般社団法人電子情報通信学会, Japanese
  • 後方散乱光時間分解計測による生体断層イメージング手法の特性評価(II)-深さ方向の点拡がりの推定-
    浪田健, 金澤瑠維, 川島雅之, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 47th, 2008
  • 後方散乱光の時間分解計測による散乱係数推定法の実験的検証
    川島雅之, 金澤瑠維, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 47th, 2008
  • Development of technique to estimate small dense LDL fraction by dynamic light scattering
    TRIRONGJITMOAH Suchin, NAMITA Takeshi, KATO Yuji, IINAGA Kazuya, CHIBA Hitoshi, SHIMIZU Koichi, Optics & Photonics Japan講演予稿集, 2008, 2008
  • Evaluation of Small Dense LDL Fraction by Dynamic Light Scattering
    TRIRONGJITMOAH Suchin, NAMITA Takeshi, SAKURAI Toshihiro, KATO Yuji, IINAGA Kazuya, CHIBA Hitoshi, SHIMIZU Koichi, 日本生体医工学会大会プログラム・論文集(CD-ROM), 47th, 2008
  • 後方散乱光時間分解計測による生体断層イメージング手法の応用-吸収体厚み推定の試み-
    浪田健, 川島雅之, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集, 2008, 2008
  • Characteristics evaluation of scattering coefficient estimation by time-resolved measurement of backscattered light-Effects of inhomogeneous optical parameters of scattering medium-
    川島雅之, 浪田健, 加藤祐次, 清水孝一, Optics & Photonics Japan講演予稿集, 2008, 2008
  • Development of estimation technique for scattering coefficient by time-resolved measurement of backscattered light
    KANAZAWA Rui, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report, 107, 460, 29, 32, Jan. 2008
    A technique was developed to estimate the scattering coefficient of diffuse medium such as a biological body by the time-resolved measurement of backscattered light. The effectiveness of the technique was confirmed in the Monte Carlo simulation. In the analysis of measurement noise, appropriate conditions of the measurement were obtained. The effect of the inhomogeneity of the absorption coefficient was investigated. The possibility to suppress the effect was demonstrated. In the case of an inhomogeneous scattering coefficient, the meaning of the time-dependent estimated value was clarified., 一般社団法人電子情報通信学会, Japanese
  • Attempt at tomographic imaging of biological body by time-resolved measurement of backscattered light
    NAMITA Takeshi, KANAZAWA Rui, KATO Yuji, SHIMIZU Koichi, 電気学会研究会資料. MBE, 医用・生体工学研究会, 2007, 36, 9, 12, Jun. 2007
    Japanese
  • Improvement in extraction of near-axis scattered light by controlling light propagation for transillumination imaging of biological bodoy
    BETTOYASHIKI Genta, TAKAGI Kazuto, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 106, 592, 25, 28, 09 Mar. 2007
    For transillumination imaging of biological body, the previously proposed technique was improved to extract near-axis scattered light efficiently. In experiments, it was verified that extraction efficiency can be improved about 10dB using the newly proposed technique. It was confirmed that the propagation area of scattered light can be largely restricted to the near-axis region. In the measurement of absorption distribution in scatterers, the possibility of accurate absorption measurement with good spatial resolution was demonstrated., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Detection of local ultrasound-modulated signal in homogeneous scattering medium by optical interferomety
    Endo Tomoki, Kato Yuji, Shimizu Koichi, IEICE technical report. ME and bio cybernetics, 106, 592, 33, 36, 09 Mar. 2007
    For the optical measurement in a scattering medium, a fundamental study was conducted on the combination of the ultrasonic modulation and the low-coherence optical interferometry. We have succeeded to detect the optical signal from the focal point of ultrasound in an optical scattering medium without using the reflecting object such as mirror. Using this optical signal, we showed the possibility of the absorption measurement in a scattering medium and clarified the application limit of this technique. Based on these results, we attempted the imaging of the absorption distribution in a scatt..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Fundamental study of reflection-type transillumination imaging for biometrics identification
    Matsubara Shinichi, Takagi Kazuto, Kato Yuji, Amano Kazuhiko, Shimizu Koichi, IEICE technical report. ME and bio cybernetics, 106, 592, 61, 64, 09 Mar. 2007
    For the application to biometrics idenfitication, a fundamental study was conducted on the reflection-type transillumination imaging that is applicable to thick biological tissue. An inhomogeneous attenuation filter was designed to compensate the inhomogeneity in the transillumination image. With this filter, the intensity resolution was improved 8 times higher and the field of view was enlarged more than 4 times larger. Considering the variation of scattering and absorption characteristics among subjects, an inhomogeneous attenuation filter was manufactured. With this filter, transillumina..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Improvement of Transcutaneous fluorescent imaging
    ITAGAKI Hidenobu, KOIZUMI Ruriko, KATO Yuji, SHIMIZU Koichi, 電気学会研究会資料. LAV, 光応用・視覚研究会, 2007, 1, 1, 5, 12 Jan. 2007
    Japanese
  • Detection of ultrasonic modulation in optical scattering medium using optical interferometry
    ENDO Tomoki, KATO Yuji, SHIMIZU Koichi, 電気学会研究会資料. LAV, 光応用・視覚研究会, 2007, 1, 7, 12, 12 Jan. 2007
    Japanese
  • 生体組織における散乱光の可干渉度の計測
    久保善弘, 浪田健, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集(CD-ROM), 46th, ROMBUNNO.PS1-14-9, 2007
    Japanese, Summary national conference
  • 後方散乱光時間分解計測による生体断層イメージング手法の改良
    浪田健, 金澤瑠維, 加藤祐次, 清水孝一, 日本分光学会講演要旨集, 2006, 136, 137, Nov. 2006
    Japanese, Summary national conference
  • 後方散乱光時間分解計測による生体模擬ファントムイメージングの試み
    浪田健, 金澤瑠維, 加藤祐次, 清水孝一, 電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM), 2006, ROMBUNNO.142, Oct. 2006
    Japanese, Summary national conference
  • Attempt to suppress optical scattering for transillumination imaging of biological body
    TAKAGI Kazuto, BETTOYASHIKI Genta, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 106, 253, 13, 16, 18 Sep. 2006
    Due to the strong scattering of biological tissue, a beam of light propagates in an off-axis area in the body. This makes the spatial resolution of the transillumination image significantly poor. To solve this problem, we propose a new technique to suppress this effect of scattering. By controlling the light propagation path in a scattering medium, we can obtain the near-axis component of the incident light beam. In experiments, the feasibility of the proposed principle was confirmed and the effectiveness was verified using a model-phantom of a biological body., The Institute of Electronics, Information and Communication Engineers, Japanese
  • 12.生体透視イメージング性能向上のための散乱光成分抑制の試み(平成17年度北海道支部大会抄録)
    高木 一人, 加藤 祐次, 清水 孝一, 生体医工学 : 日本エム・イー学会誌, 44, 2, 314, 315, 10 Jun. 2006
    社団法人日本生体医工学会, Japanese
  • 後方散乱光時間分解計測による生体断層イメージング手法改良の可能性
    浪田健, 金澤瑠雄, 加藤祐次, 清水孝一, 日本生体医工学会大会プログラム・論文集, 45th, 604, May 2006
    Japanese, Summary national conference
  • Fundamental study for transcutaneous fluorescent imaging
    KOIZUMI Ruriko, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 105, 578, 29, 32, 21 Jan. 2006
    The image observed at the body surface is deteriorated due to the strong scattering of the body tissue. To solve this problem, a fundamental study was conducted. It was confirmed that the image was improved effectively by the deconvolution with the theoretically derived point spread function (PSF). It was effective only when the depth of the fluorescent source was known a priori. We have developed a new technique to estimate the depth of the fluorescent source in the deconvolution with the derived PSF. With this technique, we can recover the correct image of the fluorescent source from the ..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • 後方散乱光時間分解計測による散乱体断層イメージングの試み(IV)‐光学特性可変固体モデルファントムによる評価‐
    浪田健, 加藤祐次, 清水孝一, 日本ME学会大会論文集, 44th, 331, Apr. 2005
    Japanese, Summary national conference
  • Attempt for scattering suppression for transillumination imaging of biological body
    TAKAGI Kazuto, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 104, 757, 1, 4, 23 Mar. 2005
    For practical transillumination imaging of biological body, we have to suppress the scattered component in transmitted light. With the previously proposed technique, mechanical scanning was necessary to obtain 2-dimensional transillumination images. We propose a new technique to eliminate this mechanical scanning. We can suppress the scattered component in the transmitted light by the weighted subtraction of the image after the scattering-increase from the image before the scattering-increase. Using a scattering plate, we can apply this technique to an animal body. The feasibility was verif..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Attempt for limiting propagation path in light scattering medium using two ultrasonic transducers
    WATANABE Eijiro, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 104, 757, 5, 8, 23 Mar. 2005
    For the measurement of NIR absorption distribution in a biological body, a new technique to use the interaction of light and ultrasound has been devised. In this technique, we provide a plural number of ultrasonic modulation regions in the scattering medium in which light propagates. Using the modulation frequency, we can selectively detect the light which passed along the straight line between the modulation regions. In experimental study, the feasibility of the proposal technique was verified. In the absorption measurement, the possibility to suppress the scattering effect was demonstrated., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Tomographic imaging of scattering object by time-resolved measurement of backscattered light : Fundamental study for practical application
    NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 104, 757, 9, 12, Mar. 2005
    A technique has been developed to obtain tomographic image of scattering object by the time-resolved measurement of backscattered light. A fundamental study was conducted to make the proposed technique practicable. The estimation error could be reduced less then half by increasing the optical power of the ultra-short pulse-laser by 100 times. The feasibility of stable CT imaging was verified by stabilizing the object. The results of this experimental study suggest that the problems of the proposed technique are not essential and that they can be technically overcome., 一般社団法人電子情報通信学会, Japanese
  • Transcutaneous fluorescent imaging with a depth-dependent point spread function.
    Shimizu K, Tochio K, Kato Y, Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference, 3, 3141, 3144, 2005, [Peer-reviewed]
  • Analysis of Spacio-Temporal Characteristics of Light Scatterig in Biological Medium
    Shimizu Ken, Kato Yuji, Shimizu Koichi, IEICE technical report. ME and bio cybernetics, 103, 730, 31, 36, 10 Mar. 2004
    For transillumination of small animal and near-surface imaging of animal body, fundamental study was conducted on the light propagation in random media. Through the measurement of attenuation, degree of polarization and coherency, it was found that the effect of multiple scattering appeared in the biological tissue with the thickness of more than 1-3 mm. Since the conventional solution of the diffusion equation is not applicable in this scattering region, new solution was derived from the equation of transfer by applying the small angle approximation. The reasonability of the solution was v..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Extraction of ultrasonic modulation in optical scattering medium using optical interference technique
    TAKAHARA Shusaku, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 103, 730, 37, 41, 10 Mar. 2004
    Fundamental study was conducted to obtain structural and functional information in a biological body using light and ultra-sound. The low coherence interferometry technique was applied to suppress the effect of the optical scattering between the modulated point and light incidence/output points. The characteristics of a measurement system and the delectability of the modulated signal by the proposed method were investigated. It was shown experimentally that the detectable depth of the modulated signal increased with the increase of the coherence length of a light source. In a phantom experi..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Estimation of depth distribution of absorption by time-resolved measurement of backscattered light
    AKIYAMA Koji, NISHIDA Yohei, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 102, 727, 1, 4, 11 Mar. 2003
    A fundamental study was conducted to realize CT imaging using backscattered light. To estimate the depth-distribution of absorption, a temporal pathlength distribution (TPD) in a scattering object is required. The TPD has been obtained in computer simulation. In this study, we proposed a technique to obtain the TPD in a real measurement. In the experiment using three-layer model phantoms, the effectiveness of the proposed technique was verified. The possibility of CT imaging was demonstrated in the reconstruction of a cross-sectional image of an absorber in a scattering object., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Transcutaneous imaging of biological information using fluorescent contrast medium
    TOCHIO Koji, TAKA Yoshinori, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 102, 727, 57, 60, 11 Mar. 2003
    To realize reflection-type transcutaneous fluorescent imaging, a fundamental study was conducted. The degree of image degradation due to scattering was investigated. The degradation can be improved by the deconvolution using a point spread function(PSF). The fluorescent image of a known object was measured and the PSF was obtained as a function of the object-depth. In a model experiment, the effectiveness of this technique was examined. The visible depth in a scattering medium became almost twice as deep using the depth-depended PSF. The usefulness of this technique was demonstrated in the ..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Detection of ultrasonic modulation effect in back-scattered light using interference technique
    WATANABE Hiromu, TAKAHARA Shusaku, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 102, 727, 61, 64, 11 Mar. 2003
    Fundamental study was conducted to obtain structural and functional information in a biological body using light and ultrasound. When we use the light modulated the light by ultrasound, a technique is required to extract the information of the modulated position from received light. Based on the principle of optical coherence tomography(KOCT), we propose a technique to detect the light component which has propagated along the straight line between the two points of ultrasonic modulation and light incidence/detection. An experimental system was constructed, and the detectability of the ultra..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Basic Study on Absorption Imaging in Biological Tissues Using Spacio-Temporal Technique
    Okamoto Yasushi, Kitama Masataka, Misawa Kenji, Arisawa Junji, Kato Yuji, Shimizu Koichi, Memoirs of the Hokkaido Institute of Technology, 31, 0, 81, 86, Mar. 2003
    北海道工業大学, Japanese
  • Absorption Imaging in Optically Turbid Medium Using Spacio-Temporal Technique
    OKAMOTO Yasushi, KITAMA Masataka, MISAWA Kenji, ARISAWA Junji, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 102, 481, 17, 20, 21 Nov. 2002
    Optical imaging of biological tissue has been difficult due to strong scattering. To realize the imaging with near-axis scattered light, we have applied the scattering-angle differential technique and the time-resolved measurement technique to the quantitative CT imaging in a turbid medium. We used a model phantom which contained a cylindrical structure with a coaxial absorption layer. CT images were reconstructed with the proposed technique and compared with those obtained with the conventional collimation technique. The spatial resolution and the accuracy of absorption were improved signi..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Fundamental study for functional measurement inside the body using near-axis scattered light : Detection by time-resolved measurement and comparison with time-gating technique
    SATO Fumihiko, SASAKI Toshikazu, KATO Yuji, SHIMIZU Koichi, 生体・生理工学シンポジウム論文集, 17, 0, 333, 336, 09 Sep. 2002
    Japanese
  • Attempt of reconstruction of absorption distribution in body using backscattered light
    KATO Y, AKIYAMA K, SHIMIZU K, 生体・生理工学シンポジウム論文集, 17, 0, 337, 340, 09 Sep. 2002
    Japanese
  • Detection of near-axis scattered light using time-resolved subtraction technique : Fundamental study of scattering measurement for optical CT
    SATO Fumihiko, SASAKI Toshikazu, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 101, 733, 79, 84, 11 Mar. 2002
    The detectability and the usefulness of the near-axis scattered light using differential time-resolved method was investigated. The efficient detection of the near-axis scattered light by the proposed technique was confirmed in the examination of the temporal and the spatial characteristics of the detected light. In the absorption measurement of inhomogeneous scatterer, the possibility and the error of the μ_a estimation was shown in comparison with the time-gatng method. The CT image obtained by the proposed technique was superior to those by the time-gating method in the spatial resolutio..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Measurement of path-length distribution for reconstruction of absorbance distribution by using back-scattered light
    KATO Y, AKIYAMA K, SHIMIZU K, レーザー学会学術講演会年次大会講演予稿集 = Annual meeting of the Laser Society of Japan digest of technical papers, 22, 0, 229, 230, 01 Jan. 2002
    Japanese
  • Fundamental study for estimation of absorption distribution in a body using backscattered light
    AKIYAMA Koji, KATO Yuji, SHIMIZU Koichi, 電気学会基礎・材料・共通部門大会講演論文集 = Proceeding of Annual Conference of Fundamentals and Materials Society, IEE Japan, 2001, 0, 242, 242, 21 Sep. 2001
    Japanese
  • Estimation of absorption distribution in scattering medium using backscattered light
    SHIMIZU K, HORIE H, AKIYAMA K, KATO Y, レーザー学会研究会報告 = Reports on the Topical meeting of the Laser Society of Japan, 289, 0, 17, 23, 07 Sep. 2001
    Japanese
  • Development of reconstruction technique for absorption distribution in biological tissue using backscattered light
    Horie Hirobumi, Kato Yuji, Shimizu Koichi, IEICE technical report. ME and bio cybernetics, 100, 685, 63, 70, 15 Mar. 2001
    For the crosssectional imaging of a biological body, a technique has been developed to reconstruct absorption distribution using time-resolved backscattered light. In this technique, we estimate the absorption distribution quantitatively by applying the operator made from a path-length distribution. In a simulation, the layered absorption distribution of a biological model was reconstructed. The reconstructed distribution agreed well with the given distribution, and the effectiveness of the proposed technique was verified. The stability of the solution in solving the inverse problem was con..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Analysis of light scattering in biological tissue for transillumination imaging : Derivation and evaluation of point spread function using small-angle approximation
    Fujiwara Isao, Taka Yoshinori, Kato Yuji, Shimizu Koichi, IEICE technical report. ME and bio cybernetics, 100, 685, 71, 76, 15 Mar. 2001
    For transillumination imaging of biological body, image degradation in scattering medium was investigated. The small-angle approximation was applied to the transfer equation to describe the light propagation in scattering medium. As an analytical solution, the point spread function (PSF) was obtained in a closed form for the case of plane-wave incidence and a Gaussian scattering pattern. The solution could well describe the spread of the PSF. To examine the reasonability of the solution, experiments were conducted to measure the PSF through scattering medium. The measured results agreed wel..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Effect of ultrasound irradiation on impulse response of backscattered light
    YAMAOKA M, KATO Y, SHIMIZU K, IEICE technical report. ME and bio cybernetics, 100, 685, 91, 96, 15 Mar. 2001
    For the reconstruction of absorption distribution in biological tissue, the application of ultrasound was proposed. The effect of the refraction-index change caused by ultrasound irradiation on the impulse response (time-resolved pulse shape) of backscattered light was investigated in a simulation study. It was found that the peak-time and the peak-magnitude of the impulse response were varied by the ultrasound irradiation on a scattering object. The relation between these variations and the wavelength/phase of ultrasound was clarified. It was also found that the optical path-length distrib..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Validation of IRFEL-induced vibrational excitation effects on ester using fluorescent dye
    FUKAMI Yuko, Ashidai Hiroshi, Obara Minoru, Morimoto Yuji, Hashishin Y., Tomita K., Nagata H., Fukai T., Nakanishi J., Matsuoka H., Shimizu Koichi, HEYA Manabu, Takagi Kentaro, Kato Yuji, Kitama Masataka, Ohmi Masato, Kurata Takayuki, Haruna Masamitsu, Mohri Shintaro, Abe Yukio, Matsuura Yuji, Kasai Takao, AWAZU Kunio, Shi Yi-Wei, Miyagi Mitsunobu, Pan Zhi-Yun, Konno Yuji, Aizawa Yoshizo, Sasaki R., Nunoyama H., Awazu K., Nakamura Masahiro, Kuwata Masahiro, Shimada Tomoaki, Nakayama Takeyoshi, Matsutani Takaomi, Nishida Yoshio, Yamanaka Masanobu, Izawa Yasukazu, Nakai Sadao, Sato Y., Tokunaga H., Ogawa Y., Oomuro H., Sato Shunichi, Harada N., Parel J. M., Murahara M., OGURA Makoto, WAKISAKA Hitoshi, Naruse Kyota, Sumiyoshi Tetsumi, Kiyoshima Shoichi, Seguchi Kenji, Arai Tsunenori, Asanuma Hiroshi, Sakata Isao, Takemura Takeshi, Nakajima Susumu, Ishihara Miya, Kawauchi Satoko, Kikuchi Makoto, The Review of Laser Engineering, 29, 0, 221, 222,224, 2001
    The Laser Society of Japan
  • Basic study for transillumination imaging of biological functions using near-infrared light
    TAKA Yoshinori, KATO Yuji, SHIMIZU Koichi, レーザー学会研究会報告 = Reports on the Topical meeting of the Laser Society of Japan, 268, 0, 23, 27, 12 Nov. 1999
    Japanese
  • Analysis of intensity modulated light in frequency domain for measurement of absorption distribution in turbid media
    YAMAZAKI Kinya, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 98, 671, 39, 46, 18 Mar. 1999
    With intensity-modulated CW light, the same analysis is possible as the time-resolved technique for the scattering phenomena in mammalian tissues. Mainly in simulation, we analyzed the frequency response of scattering medium with inhomogeneous absorption coefficient. Two models were analyzed, i.e. a transmission-type and a reflection-type. In practical conditions, the frequency response of the reflection-type was more sensitive to the absorption change than that of the transmission-type. In the reflection-type, it was found that the frequency response was sensitive to the positions and the ..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Detection of near-axis scattered light using time-resolved measurement technique
    TAKAGI Kentaro, KATO Yuji, KITAMA Masataka, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 98, 671, 53, 59, 18 Mar. 1999
    In the transmitted light through scattering mammalian tissue, there should be a component which traveled along the optical axis of incident light beam. To separate this near-axis scattered light, we have introduced a time-resolved measurement technique to the previously developed spatially differential technique. With this technique, we can accurately determine the weighting coefficient for the differential process. In addition, we can estimate the increase of the pathlength in near-axis scattering. Through experimental study, the effectiveness of this technique was verified, and the useful..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Experimental Study for Functional Imaging with Optical Coherence Tomography
    IKEYA Masao, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 97, 621, 57, 63, 19 Mar. 1998
    Fundamental stydy was conducted for the functional imaging with the OCT technique. The possibility of imaging with the spatial resolution of 17μm was confirmed. The interference signals were measured at the surfaces with different scattering and absorption coefficients. The following facts were found. The signal intensity does not depend largely on the change in a scattering coefficient. We can detect the surface of different absorption coefficients, and measure the change in an absorption coefficient. With the developed system, the surface of a light-absorbing object was visualized in a sc..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Cross-sectional imaging of absorption distribution in biological tissue using backscattered light : Development of reconstruction technique for absorption distribution
    AWATA Aki, KATO Yuji, SHIMIZU Koichi, IEICE technical report. ME and bio cybernetics, 97, 525, 87, 94, 31 Jan. 1998
    A technique was developed to reconstruct the cross-sectional image of the absorption distribution in a diffuse medium using backscattered light. With this technique we can get physiological information such as hemoglobin oxygenation in the body noninvasively. In this technique, we illuminate an object with an ultra-short pulse, and measure the time-resolved pulse shape of the light backscattered from the object. The absorption distribution of the scattering object can be estimated using the path-length distribution of photons at each detection time and the intensity of backscattered light a..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Time-resolved analysis of optical scattering in biological tissues using CW light
    HARADA T, KATO Y, SHIMIZU K, IEICE technical report. ME and bio cybernetics, 96, 581, 57, 62, 17 Mar. 1997
    For the analysis of light propagation in scattering random media, a technique was developed which enables us to reconstruct a time-resolved pulse-shape using intensity modulated CW light. A measurement system was developed, and the feasibility of this technique was verified experimentally. Using the medium with different scattering and absorption coefficients, time-resolved pulse shapes were reconstructed. The reasonability of the result was ascertained in the comparison with the pulse-shapes measured in a time-domain., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Attempt to improve visibility in light scattering medium
    HIRAYAMA T, KATO Y, SHIMIZU K, IEICE technical report. ME and bio cybernetics, 96, 581, 63, 69, 17 Mar. 1997
    To improve the visibility in a scattering medium, a new technique was developed which suppresses the effect of scattering by averaging out the randomness of scattering. First, the degree of the improvement was investigated by quantifying the visibility. The effectiveness of this technique was verified in the imaging of the structure behind various scattering objects. In practical use, this technique can be used with a pair of collimated light source and detector in a rotate-translate mode. The possibility of this mode was demonstrated., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Optical data transmission between medical devices using spread spectrum technique : Attempt of multichannel transmission using indirectly scattered light
    TOYA N, KATO Y, SHIMIZU K, IEICE technical report. ME and bio cybernetics, 96, 581, 85, 90, 17 Mar. 1997
    To realize the wireless integration of many medical equipments, a fundamental study was conducted. The possibility of multichannel data-transmission using a spread spectrum technique and indirectlight communication was investigated. Instead of ASK, PSK was used for the primary modulation. For the error control, ARQ technique was introduced. The input level of a SAW convolver was stabilized with an AGC circuit. With these improvements, the data transmission became possible even in the condition with a negative CNR. In ECG transmission, the quality was satisfactory even when the CNR is close ..., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Characteristics of Polyimide Coated Silver Hollow Glass Waveguide for Er:YAG Laser
    Suzumura Masato, Kato Yuji, Miyagi Mitsunobu, Proceedings of the IEICE General Conference, 1997, 1, 215, 215, 06 Mar. 1997
    Er:YAGレーザは光を含む電磁波の中で水に対する吸収が最も大きいということから, 歯科無痛治療等の医療分野で大きく注目されている。筆者等は, このEr:YAGレーザ光用の伝送路としてポリイミド樹脂内装銀中空ガラス導波路の開発を行ってきている。今回, 導波路の長さをこれまでの1 m程度から2 m程度と長尺にして製作を行い, その伝送特性の測定を行った。また, 導波路の機械強度の評価も行ったので, 併せて報告する。, The Institute of Electronics, Information and Communication Engineers, Japanese
  • Optical Transillumination Imaging of Biological Body
    SHIMIZU Koichi, KATO Yuji, YAMAMOTO Katsuyuki, rle, 17, 0, 308, 311, 01 Jan. 1997
    The Laser Society of Japan, Japanese
  • Fabrication of Polyimide-coated Silver Hollow Glass Waveguides for Er : YAG Laser
    SUZUMURA Masato, WANG You, KATO Yuji, HONGO Akihito, MIYAGI Mitsunobu, レーザー学会研究会報告 = Reports on the Topical meeting of the Laser Society of Japan, 230, 7, 11, 25 Jul. 1996
    Japanese
  • Trans-Body Imaging with Light
    SHIMIZU Koichi, KATO Yuji, YAMAMOTO Katsuyuki, レーザー学会研究会報告 = Reports on the Topical meeting of the Laser Society of Japan, 230, 0, 37, 42, 25 Jul. 1996
    Japanese
  • Fundamental study to obtain in vivo functional information using backscattered light : Application of low-coherence light interferometry
    Takaya J, Kitama M, Kato Y, Shimizu K, Yamamoto K, Kaneko M, IEICE technical report. ME and bio cybernetics, 95, 597, 19, 24, 19 Mar. 1996
    A fundamental study has been conducted on the applicability of low-coherence interferometry to the functional CT imaging of biological tissues with light. First, we examined the effectiveness of the proposed technique to suppress the scattering component in the transmitted light. Then, it was shown that we could estimate the absorption coefficient of a scattering medium even in the strong scattering like in a living tissue. Finally, this technique was applied to a rat blood. Using two different wavelengths of light, we could detect the local change in the redox state of the blood., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Optimization of Fablication Condition for Silver-Hollow Glass Waveguides
    Kubota Satoshi, Kato Yuji, Akama Yosuke, Miyagi Mitsunobu, Proceedings of the IEICE General Conference, 1996, 1, 265, 265, 11 Mar. 1996
    赤外域に発振波長を持つ高出力レーザ光の伝送路として、石英キャピラリーチューブ内に銀層並びに有機樹脂薄膜を有する、誘電体内装中空導波路が提案されている。銀層の成膜には簡便な銀鏡反応が用いられているが、銀中空導波路の特性は誘電体内装後の伝送路の特性に大きな影響を及ぼす。本報告では、光学特性の測定及びSEMによる銀中空導波路の内面観察から、銀中空導波路製作の最適条件について報告する。, The Institute of Electronics, Information and Communication Engineers, Japanese
  • Fabrication of Polyimide-Coated Silver Hollow Glass Waveguides for the Infrared Laser
    SUZUMURA Masato, KATO Yuji, SHIMOMURA Takehiro, MIYAGI Mitsunobu, レーザー学会学術講演会年次大会講演予稿集 = Annual meeting, of the Laser Society of Japan digest of technical papers, 16, 321, 321, 01 Jan. 1996
    Japanese
  • Fabrication of FCP-Coated Silver Hollow Glass Waveguides for Infrared Laser Light Transmission
    WANG You, KATO Yuji, SHIMOMURA Takehiro, MIYAGI Mitsunobu, レーザー学会学術講演会年次大会講演予稿集 = Annual meeting, of the Laser Society of Japan digest of technical papers, 16, 320, 320, 01 Jan. 1996
    Japanese
  • Loss Characteristics of Fluorocarbon Polymer-Coated Silver Hollow Glass Waveguides with Small Diameter
    Osawa M., Kato Y., Miyagi M., Abe S., Aizawa M., Onodera S., Proceedings of the IEICE General Conference, 1995, 1, 272, 272, 27 Mar. 1995
    Er:YAGレーザ等の高出力赤外レーザ光は医療分野、工業加工分野においての応用が盛んに進められている。それらレーザ光をフシキシブルかつ高効率に伝送する装置として誘電体内装中空導波路が研究されており、筆者らはガラスキャピラリーチューブ内面に銀鏡反応及び弗素樹脂(FCP)のDip-coatingによりFCP内装銀中空ガラス導波路(FCP/Ag導波路)を製作している。本論文において、銀鏡反応による銀チューブ製作の再現性の向上及び低損失化、また製作したFCP/Ag導波路の損失波長特性、及びEr.YAGレーザ光伝送特性について報告する。, The Institute of Electronics, Information and Communication Engineers, Japanese
  • Loss Characteristics of Polyimide-Coated Silver Hollow Glass Weveguides for Er : YAG Laser Light
    KATO Y., OSAWA M., KUBOTA S., MIYAGI M., ABE S., AIZAWA M., ONODERA S., レーザー学会学術講演会年次大会講演予稿集 = Annual meeting, of the Laser Society of Japan digest of technical papers, 15, 308, 308, 01 Jan. 1995
    Japanese
  • 赤外レーザ用中空導波路
    加藤祐次, レーザ学会研究会報告, 37, 41, 1995
  • Fabrication of flexible polyimide-coated hollow glass waveguides for the infrared
    Kato Yuji, Ohsawa Mitsuo, Miyagi Mitsunobu, Aizawa Masaru, Abe Shin-ichi, Onodera Shinji, Technical report of IEICE. OCS, 94, 335, 1, 6, 17 Nov. 1994
    Polyimide-polymer coated silver hollow infrared waveguides with 700 μm inner diameter and 1 m length have been fabricated for the medical applications.By measurements of the loss spectra and loss for the Er:YAG laser light of the wave guides,it is shown that this waveguides have low-loss characteristics.The heat resisting polyimide-polymer has many advantages over other dielectrics such as non-toxicity and durability.Furthermore,by using silica capillary tube as a base tube,this waveguide is shown to be very flexible., The Institute of Electronics, Information and Communication Engineers, Japanese
  • Fabrication of Resin-Coated Silver Hollow Waveguides by Inner Liquid-Phase Coating
    Osawa M., Kato Y., Miyagi M., Abe S., Aizawa M., Onodera S., 電子情報通信学会秋季大会講演論文集, 1994, 1, 224, 224, 26 Sep. 1994
    現在医療分野へのEr:YAG、CO、CO_2等の赤外レーザの応用が盛んに進められており、それら赤外レーザ光をフレキシブルかつ高効率に伝送する装置として誘電体内装金属中空導波路が研究されている。医療用の導波路には量産性及び細径化が必要であり、内装する誘電体としては人体に対して無害かつ対環境性に優れているものが望まれる。今回これらの要件を念頭に置き、ガラスパイプ内面に銀及びフッ素樹脂を内付け法により成膜し、導波路を製作した。, The Institute of Electronics, Information and Communication Engineers, Japanese
  • Polymid and Silver Layers-Coated Hollow Glass Waveguides for Infrared Light Transmission
    Kato Y., Osawa M., Miyagi M., Abe S., Aizawa M., Onodera S., 電子情報通信学会秋季大会講演論文集, 1994, 1, 223, 223, 26 Sep. 1994
    近年、Er:YAGやCO_2レーザ等の赤外レーザは医療用の治療デバイスとして大きく注目されている。これらレーザ光の効率的な利用には、フレキシブルな伝送媒体が重要であり、大きな切開を必要としない最小侵装医療やレーザの特徴を生かした歯科無痛治療の進展に、伝送路は不可欠である。筆者等は、これら赤外レーザ光用の伝送路として誘電体内装中空導波路の開発を行ってきているが、導波路の細径化と低損失化が大きな課題となっている。この課題を解決するために、内付け技術を用いた銀及び有機材料の成膜による導波路の製作技術について研究を行っている。本報告では、内装する誘電体としてポリイミド樹脂を新たに取り上げ、製作した導波路の伝送特性等について述べる。, The Institute of Electronics, Information and Communication Engineers, Japanese

Books and other publications

Lectures, oral presentations, etc.

  • Evaluation of controlled release from doxorubicin-loaded nanoparticles under ultrasound irradiation　　　　　　　　　　　　　　　
    新里美瑠, 加藤祐次, 橋本守, 工藤信樹
    日本生体医工学会大会プログラム・抄録集(Web), 2021
    2021 - 2021
  • Influence of optical properties of surrounding medium on vein diameter and depth estimation for non-invasive measurement of lipid concentration in blood　　　　　　　　　　　　　　　
    難波昂暉, 加藤祐次
    応用物理学会北海道支部/日本光学会北海道支部合同学術講演会講演予稿集, 2021
    2021 - 2021
  • Improvement of scattering suppression effect of time-reversal propagation using digital phase-conjugate light
    Sogo Toda, Yuji Kato, Nobuki Kudo, Koichi Shimizu
    Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 01 Jan. 2019, English
    01 Jan. 2019 - 01 Jan. 2019
  • 脂質濃度可変静脈モデルファントムを用いた無侵襲血中脂質濃度光学計測法の有効性の検討
    下川部一真, 高見澤淳, 飯永一也, 橋本守, 加藤祐次
    日本生体医工学会大会プログラム・抄録集(Web), 2019, Japanese
  • Attempt for recovering light source image through animal tissue using digital phase-conjugate light
    任田崇吾, 加藤祐次, 工藤信樹, 清水孝一
    レーザー学会研究会報告, 2018, Japanese
  • 後方散乱光を用いた血中トリグリセリド濃度の非侵襲的計測法 予備的検証　　　　　　　　　　　　　　　
    松村 健太, 加藤 祐次, 飯永 一也, 清水 孝一
    脂質栄養学, Aug. 2017, 日本脂質栄養学会, Japanese
    Aug. 2017 - Aug. 2017
  • 光透視による支台歯マージン形状の検出の試み(第2報)
    上田康夫, 加藤祐次, 山口泰彦, 清水孝一
    日本デジタル歯科学会誌(Web), Apr. 2017, Japanese
  • 散乱体内部吸光構造の三次元像再構成に関する基礎的検討
    加藤祐次, 宮島文佳, 清水孝一
    レーザー学会研究会報告, 2017, Japanese
  • 光透視による支台歯マージン形状の検出の試み(第3報)
    上田康夫, 加藤祐次, 山口泰彦, 清水孝一
    日本補綴歯科学会誌(Web), 2017, Japanese
  • 後方散乱光を用いた血中トリグリセリド濃度の非侵襲的計測法:予備的検証
    松村健太, 加藤祐次, 飯永一也, 清水孝一
    脂質栄養学, 2017, Japanese
  • ディジタル位相共役光を用いた散乱体透視イメージングの基礎的検討―位相共役光の強度成分が散乱抑制に及ぼす影響の評価―
    任田崇吾, 加藤祐次, 工藤信樹, 清水孝一
    Optics & Photonics Japan講演予稿集(CD-ROM), 15 Oct. 2016, Japanese
  • Fundamental study for transillumination imaging of biological body using digital phase-conjugate optics
    任田崇吾, 加藤祐次, 清水孝一
    電子情報通信学会技術研究報告, 15 Mar. 2016, Japanese
  • Experimental study to improve transillumination image by depth estimation using light sources of two wavelengths
    岡崎恵祐, 加藤祐次, 清水孝一
    電子情報通信学会技術研究報告, 15 Mar. 2016, Japanese
  • Fundamental study for measurement of scattering coefficient using backscattered light-For noninvasive measurement of blood triglyceride level-
    WANG Lei, 飯永一也, 加藤祐次, 清水孝一
    電子情報通信学会技術研究報告, 15 Mar. 2016, Japanese
  • Fundamental study to improve accuracy of 3D reconstruction technique using optical transillumination images of animal body
    宮島文佳, 加藤祐次, 清水孝一
    電子情報通信学会技術研究報告, 15 Mar. 2016, Japanese
  • Experimental study for scattering suppression effect using digital phase-conjugate optics
    Sogo Toda, Yuji Kato, Nobuki Kudo, Koichi Shimizu
    Transactions of Japanese Society for Medical and Biological Engineering, 01 Jan. 2016
    © 2016, Japan Soc. of Med. Electronics and Biol. Engineering. All rights reserved. The scattering effect in light propagation through random media can be suppressed with the phase-conjugate optics. We have applied this technique to the transillumination imaging of animal body using a digital phase-conjugate system. In the experiment, we attempted to restore various incident light patterns through a scattering medium. As a result, the feasibility of scattering suppression using digital phase-conjugate light was verified.
  • 散乱体透視のためのディジタル位相共役光イメージングの試み
    任田崇吾, 加藤祐次, 清水孝一
    電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM), 07 Nov. 2015, Japanese
  • 光透視による三次元像再構成手法の精度向上に関する基礎的検討
    宮島文佳, 加藤祐次, 清水孝一
    Optics & Photonics Japan講演予稿集(CD-ROM), 15 Oct. 2015, Japanese
  • 後方散乱光による中性脂肪濃度非侵襲計測の検討
    WANG Lei, 飯永一也, 加藤祐次, 磯村哲, 清水孝一
    Optics & Photonics Japan講演予稿集(CD-ROM), 15 Oct. 2015, Japanese
  • 2波長光源を用いた光透視画像改善方法の実験的検討
    岡崎恵祐, 加藤祐次, 清水孝一
    Optics & Photonics Japan講演予稿集(CD-ROM), 15 Oct. 2015, Japanese
  • ディジタル位相共役光による散乱体内部イメージングのための実験的検討
    任田崇吾, 加藤祐次, 清水孝一
    Optics & Photonics Japan講演予稿集(CD-ROM), 15 Oct. 2015, Japanese
  • Fundamental Study for Practical Personal Authentication by Transillumination Imaging of Blood Vessels at Wrist
    開田翔一, 松村健太, 加藤祐次, 清水孝一
    電子情報通信学会技術研究報告, 09 Mar. 2015, Japanese
  • Fundamental study for reconstruction of in vivo fluorescent tomographic image using orthogonal function system.
    佐々木洋天, 浪田健, 加藤祐次, 清水孝一
    電子情報通信学会技術研究報告, 09 Mar. 2015, Japanese
  • Fundamental study on scattering suppression technique using equation of beam-wave propagation for optical transillumination imaging
    田中宏幸, 浪田健, 加藤祐次, 清水孝一
    電子情報通信学会技術研究報告, 09 Mar. 2015, Japanese
  • Fundamental study for practical application of optical communication through human body
    関大輔, 浪田健, 加藤祐次, 清水孝一
    電子情報通信学会技術研究報告, 09 Mar. 2015, Japanese
  • 手首血管による個人認証のための基礎的検討:II―光透視像の画像相関の可能性―
    開田翔一, 松村健太, 加藤祐次, 清水孝一
    電気学会全国大会講演論文集(CD-ROM), 05 Mar. 2015, Japanese
  • 手首血管による個人認証のための基礎的検討
    開田翔一, 松村健太, 加藤祐次, 清水孝一
    応用物理学会北海道支部・日本光学会北海道地区合同学術講演会講演予稿集, 09 Jan. 2015, Japanese
  • 散乱体内部構造イメージングの基礎的検討―生体の三次元光透視をめざして―
    宮島文佳, 加藤祐次, 清水孝一
    応用物理学会北海道支部・日本光学会北海道地区合同学術講演会講演予稿集, 09 Jan. 2015, Japanese
  • 後方散乱光による中性脂肪無侵襲計測の基礎的検討
    WANG Lei, 飯永一也, 加藤祐次, 清水孝一
    日本生体医工学会大会プログラム・論文集(CD-ROM), 2015, Japanese
  • 光透視による三次元像再構成に関する基礎的検討
    宮島文佳, 加藤祐次, 清水孝一
    日本生体医工学会大会プログラム・論文集(CD-ROM), 2015, Japanese
  • 2波長光源を用いた吸光体深さ推定の実験的検証
    岡崎恵祐, 加藤祐次, 清水孝一
    日本生体医工学会大会プログラム・論文集(CD-ROM), 2015, Japanese
  • 散乱媒質におけるディジタル位相共役光によるタイムリバース法の実験的検討
    任田崇吾, 加藤祐次, 清水孝一
    日本生体医工学会大会プログラム・論文集(CD-ROM), 2015, Japanese
  • 光による中性脂肪非侵襲計測の基礎的検討
    WANG Lei, 飯永一也, 加藤祐次, 清水孝一
    電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM), 25 Oct. 2014, Japanese
  • 2波長光源による光透視画像改善方法の開発
    岡崎恵祐, 加藤祐次, 清水孝一
    電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM), 25 Oct. 2014, Japanese
  • ビーム光の散乱体内部伝搬式を用いた生体透視における散乱抑制手法の基礎的検討
    田中宏幸, 浪田健, 加藤祐次, 清水孝一
    Optics & Photonics Japan講演予稿集(CD-ROM), 24 Oct. 2014, Japanese
  • Development of new optical CT for 3D animal imaging using NIR transillumination images　　　　　　　　　　　　　　　
    Tran Trung Nghia, Kohei Yamamoto, Takeshi Namita, Yuji Kato, Koichi Shimizu
    IEICE Tech. Rep, Jun. 2014, English, Oral presentation
  • Development of new optical CT for 3D animal imaging - Practical technique using transillumination images -　　　　　　　　　　　　　　　
    Trung Nghia Tran, Kohei Yamamoto, Takeshi Namita, Yuji Kato, Koichi Shimizu
    Biomedical Imaging and Sensing Conference, part of Optics & Photonics International 2014 Congress, May 2014, English, Oral presentation
  • Attempt for optical BAN on human body　　　　　　　　　　　　　　　
    Daisuke Seki, Takeshi Namita, Yuji Kato, Koichi Shimizu
    Proceedings of 20 th Symposium of the Internationa Society on Biotelemetry, May 2014, English, Oral presentation
  • 後方散乱光時間分解計測による吸収係数分布の高精度推定の試み　　　　　　　　　　　　　　　
    大場一寛, 横山直弥, 浪田 健, 加藤祐次, 清水孝一
    電子情報通信学会技術研究報告, Mar. 2014, Japanese, Oral presentation
  • 光による生体透視イメージングのための拡散媒質内部吸光像の画像改善　　　　　　　　　　　　　　　
    山本航平, チャン チュン ギア, 浪田 健, 加藤祐次, 清水孝一
    電子情報通信学会技術研究報告, Mar. 2014, Japanese, Oral presentation
  • 円柱状光拡散体における内部蛍光体イメージング手法の開発 ～ 生体内部蛍光体の経皮透視をめざして ～　　　　　　　　　　　　　　　
    小川大貴, 浪田 健, 加藤祐次, 清水孝一
    電子情報通信学会技術研究報告, Mar. 2014, Japanese, Oral presentation
  • 実測点拡がり関数を用いた前腕血管の光透視 ～ 人工透析における内シャント管理への応用 ～　　　　　　　　　　　　　　　
    夏目裕也, 浪田 健, 加藤祐次, 北間正崇, 清水孝一
    電子情報通信学会技術研究報告, Mar. 2014, Japanese, Oral presentation
  • 3D reconstruction of internal structure of animal body using near-infrared light　　　　　　　　　　　　　　　
    Tran Trung Nghia, Kohei Yamamoto, Takeshi Namita, Yuji Kato, Koichi Shimizu
    Proc. SPIE, Feb. 2014, English, Oral presentation
  • 3D reconstruction of internal structure of animal body using near-infrared light
    Trung Nghia Tran, Kohei Yamamoto, Takeshi Namita, Yuji Kato, Koichi Shimizu
    Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 01 Jan. 2014
    To realize three-dimensional (3D) optical imaging of the internal structure of animal body, we have developed a new technique to reconstruct CT images from two-dimensional (2D) transillumination images. In transillumination imaging, the image is blurred due to the strong scattering in the tissue. We had developed a scattering suppression technique using the point spread function (PSF) for a fluorescent light source in the body. In this study, we have newly proposed a technique to apply this PSF for a light source to the image of unknown light-absorbing structure. The effectiveness of the proposed technique was examined in the experiments with a model phantom and a mouse. In the phantom experiment, the absorbers were placed in the tissue-equivalent medium to simulate the light-absorbing organs in mouse body. Near-infrared light was illuminated from one side of the phantom and the image was recorded with CMOS camera from another side. Using the proposed techniques, the scattering effect was efficiently suppressed and the absorbing structure can be visualized in the 2D transillumination image. Using the 2D images obtained in many different orientations, we could reconstruct the 3D image. In the mouse experiment, an anesthetized mouse was held in an acrylic cylindrical holder. We can visualize the internal organs such as kidneys through mouse's abdomen using the proposed technique. The 3D image of the kidneys and a part of the liver were reconstructed. Through these experimental studies, the feasibility of practical 3D imaging of the internal light-absorbing structure of a small animal was verified. © 2014 SPIE.
  • Fundamental study for optical BAN
    Koichi Shimizu, Takeshi Namita, Yuji Kato
    Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST, 01 Dec. 2013
    For a new optical body area network (BAN) technique, a fundamental study was conducted of optical data transmission through a human body using diffusely scattered light. The frequency bandwidth for data transmission was restricted by the effect of strong scattering inside body tissues. In experiments using human bodies, the possibility of the transmission up to 100 MHz was confirmed. Using the linear equalization process, we can transmit an 800 MHz square wave signal. Data transmission of around 200 mm distance in a human hand was possible. To overcome problems of noise, multipath transmission, and the instantaneous interruption of data transmission, the space diversity (SD) technique was applied to stabilize data communications. The SD technique effectiveness was confirmed through analysis using real optical impulse responses. The feasibility of BAN using diffusely scattered light in the body was verified through these analyses. © Institute for Computer Sciences, Social Informatics and Telecommunications Engineering 2013.
  • Application of fluorescent PSF for 3D reconstruction of absorbing structure using slab transillumination images
    Trung Nghia Tran, Takeshi Namita, Yuji Kato, Koichi Shimizu
    Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS, 31 Oct. 2013
    In transillumination imaging of an animal body using near-infrared light, the image is blurred due to the strong scattering in the tissue. We have devised the depth-dependent point spread function (PSF) to suppress the scattering effect in fluorescent imaging. In this study, we applied this principle and developed a technique to reconstruct the absorbing structure in turbid medium without using fluorescent material. In experiments, the feasibility and effectiveness of the proposed technique were verified. © 2013 IEEE.
  • New reconstruction technique for 3 dimensional structure in shallow layer of turbid medium using optical transillumination images - Attempt for reconstruction with limited view angle
    Taiki Matsuura, Takeshi Namita, Yuji Kato, Koichi Shimizu
    Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS, 31 Oct. 2013
    In transillumination imaging of an animal body with near-infrared light, the shallower structure appears clearer. Therefore, we can reconstruct the three dimensional (3D) image of the shallow structure using the transillumination images as the projection images. In the 3D reconstruction, it may be better to use the projection images of limited observation-angle range rather than those from 360° range. We investigated this possibility and devised a new technique to reconstruct the 3D image of the light absorbing structure in shallow region of a turbid medium. This technique is applicable to the turbid object without any a priori knowledge on the angular position of the absorbing structure. The feasibility of the proposed technique was verified in experiments. © 2013 IEEE.
  • Fundamental study for thickness estimation of fluorescent object in scattering medium using dual wavelength excitation
    OBATA KYOHEI, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI
    電子情報通信学会技術研究報告, Mar. 2013, Japanese, Oral presentation
  • Fundamental study on CT imaging of tissue oxygen saturation by time-resolved measurement of backscattered light
    MORIMOTO TAKURO, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI
    電子情報通信学会技術研究報告, Mar. 2013, Japanese, Oral presentation
  • Depth estimation and image improvement of fluorescent objects in turbid medium with unknown optical coefficients
    XIA JIAO, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI
    電子情報通信学会技術研究報告, Mar. 2013, Japanese, Oral presentation
  • Development of technique for improvement of optical transillumination images using equation of beam wave propagation
    OKUYAMA YUKI, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI
    電子情報通信学会技術研究報告, Mar. 2013, Japanese, Oral presentation
  • Attempt for optical data transmission through human palm
    AKIYAMA JUNKICHI, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI
    電子情報通信学会技術研究報告, Mar. 2013, Japanese, Oral presentation
  • Reconstruction technique for 3 dimensional structure in shallow layer of turbid medium using optical transillumination images-Attempt for reconstruction with limited view angle-
    MATSUURA TAIKI, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI
    電子情報通信学会技術研究報告, Mar. 2013, Japanese, Oral presentation
  • Experimental study for imaging through scattering medium by time reversal method using phase conjugate optics
    YOKOTA SHUN, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI
    電子情報通信学会技術研究報告, Mar. 2013, Japanese, Oral presentation
  • 後方散乱光による高確度吸収係数分布推定法の多層構造への適用
    加藤祐次, 浪田健, 清水孝一
    電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM), 20 Oct. 2012, Japanese
  • 光を用いた人体通信の基礎的検討
    関大輔, 浪田健, 加藤祐次, 清水孝一
    電子情報通信学会大会講演論文集(CD-ROM) 2013 ROMBUNNO.BS-9-5, Sep. 2012, Japanese, Oral presentation
  • 多波長を用いた生体機能の断層イメージングの試み―断層イメージングのための波長選定―
    森本拓朗, 浪田健, 加藤祐次, 清水孝一
    生体医工学, 10 Aug. 2012, Japanese
  • Development of absorption distribution estimation technique using backscattered light with scattering characteristic measurement
    OTANI MASAFUMI, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI
    電子情報通信学会技術研究報告, 07 Mar. 2012, Japanese
  • Fundamental study for 3D reconstruction of fluorescent object in biological body
    TOZAWA EIJI, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI
    電子情報通信学会技術研究報告, 07 Mar. 2012, Japanese
  • Development of accurate estimation technique for absorption distribution by time-resolved measurement of backscattered light
    SUGIYAMA KEITA, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI
    電子情報通信学会技術研究報告, 07 Mar. 2012, Japanese
  • Improvement of transillumination image of blood vessels using multiple wavelengths of light
    NISHIDA KOHEI, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI
    電子情報通信学会技術研究報告, 07 Mar. 2012, Japanese
  • Arteriovenous discrimination by spectroscopic analysis of transillumination images
    MATSUDA YASUSHI, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI
    電子情報通信学会技術研究報告, 07 Mar. 2012, Japanese
  • Development of restoration technique for biological absorption image in turbid medium using point spread function
    TAKAHASHI HIROKI, NAMITA TAKESHI, KATO YUJI, SHIMIZU KOICHI
    電子情報通信学会技術研究報告, 07 Mar. 2012, Japanese
  • 複数波長励起による散乱体中の蛍光体厚さ推定のための基礎的検討
    小幡恭平, 浪田健, 加藤祐次, 清水孝一
    日本生体医工学会大会プログラム・論文集(CD-ROM), 2012, Japanese
  • 手掌を介した光データ通信の試み
    秋山潤吉, 浪田健, 加藤祐次, 清水孝一
    日本生体医工学会大会プログラム・論文集(CD-ROM), 2012, Japanese
  • Fundamental Study for Optical BAN.
    Koichi Shimizu, Takeshi Namita, Yuji Kato
    Wireless Mobile Communication and Healthcare - Third International Conference, MobiHealth 2012, Paris, France, November 21-23, 2012, Revised Selected Papers, 2012, English, Oral presentation
  • Reconstruction of 3-dimensional structure in scattering medium from transillumination images using scattering suppression technique
    SHIMANO Moto, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 28 Feb. 2011, Japanese
    To see through a turbid medium, a technique was developed to reconstruct a three-dimensional structure inside the medium. Clear transillumination images were obtained with a scattering suppression technique in which the weakly scattered light component can be extracted from the strongly diffused light. The possibility of the proposed technique was examined in the experiment using the turbid medium with known internal structure. Through the experimental analysis, the feasibility of the proposed technique and the effectiveness of the scattering suppression were verified.
  • Development of simultaneous observation system for transillumination imaging of blood vessels using visible and near-infrared light
    TOBISAWA Naoya, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 28 Feb. 2011, Japanese
    To assist vascular injection, we have developed a simultaneous observation system using a body surface image and a transillumination image of blood vessels. Light source was devised to make homogeneous, wide-area and low-leak illumination possible. Using the developed system, we could obtain the transillumination images in all part of the adult forearm with as much as 67 mm thickness. In addition to the superficial veins, we could visualize the arteries in the forearm. Its usefulness was examined in the simulation of injection with a phantom of the human forearm.
  • Injection Assist System with Surface and Transillumination Images　　　　　　　　　　　　　　　
    Naoya Tobisawa, Takeshi Namita, Yuji Kato, Koichi Shimizu
    The 5th International Conference on Bioinformatics and Biomedical Engineering, 2011, English, Oral presentation
  • Reconstruction of Three-Dimensional Structure in Turbid Medium by Scattering Suppression　　　　　　　　　　　　　　　
    Moto Shimano, Takeshi Namita, Yuji Kato, Koichi Shimizu
    The International Symposium on Photonics and Optoelectronics (SOPO 2011), 2011, English, Oral presentation
  • New technique to estimate non-absorbing temporal point spread function for diffuse optical tomography using backscattered light　　　　　　　　　　　　　　　
    Takeshi Namita, Masafumi Otani, Yuji Kato, Koichi Shimizu
    IQEC/CLEO Pacific Rim 2011 Conference Proceedings, 2011, English, Oral presentation
  • 3D reconstruction of internal structure of animal body using NIR light – Preliminary results for feasibility study -　　　　　　　　　　　　　　　
    Trung Nghia TRAN, Takeshi Namita, Yuji Kato, Koichi Shimizu
    The 1st International Symposium on Engineering Physics and Mechanics, 2011, English, Oral presentation
  • Feasibility study for 3D reconstruction of internal structure of animal body using NIR light　　　　　　　　　　　　　　　
    Trung Nghia Tran, Takeshi Namita, Yuji Kato, Koichi Shimizu
    Proceedings of the 4th International Conference on the Development of Biomedical Engineering, 2011, English, Oral presentation
  • Application of transillumination imaging to injection assist system　　　　　　　　　　　　　　　
    Koichi Shimizu, Naoya Tobisawa, Trung Nghia Tran, Takeshi Namita, Yuji Kato
    Proceedings of the 4th International Conference on the Development of Biomedical Engineering, 2011, English, Oral presentation
  • Point Spread Function for Optical Transillumination Imaging of Animal Body　　　　　　　　　　　　　　　
    Koichi Shimizu, Hiroki Takahashi, Takeshi Namita, Yuji Kato
    The 31st PIERS, 2011, English, Oral presentation
  • Development of practical transcutaneous fluorescent imaging technique using measured PSF
    TAKESHITA Yusuke, KATO Yuji, DATE Hiroyuki, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 02 Mar. 2010, Japanese
    A new technique was developed to realize the fluorescence angiography based on the image restoration with point-spread function (PSF). In this technique, the PSF can be obtained using a fluorescence-marked stent placed in a blood vessel. A clear image of the blood vessel can be restored by deconvolving the blurred transcutaneous image with measured PSF. In simulation, the feasibility of the basic idea was confirmed. In the experiments with tissue phantoms, the effectiveness of the proposed technique was verified. Those results suggest the feasibility of the repetitive examination of vessel ...
  • Depth estimation and image improvement of fluorescent objects in scattering medium by reflection-type measurement with two light sources
    SHIMIZU Atsushi, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 02 Mar. 2010, Japanese
    Transcutaneous fluorescent images are deteriorated due to the optical scattering of body tissues. Using a depth-depending PSF(point spread function), this effect can be suppressed effectively. We have newly developed a technique to estimate the depth of a fluorescent object in a scattering medium with two light sources. The effectiveness of this technique was confirmed in the experiment with a simple fluorescent object in a scattering medium. Then the proposed technique was improved so as to be applicable to the case of multiple fluorescent objects at different depths. Using model phantoms ...
  • Characteristic analysis of optical backscattering enhancement through time-resolved measurements of near-infrared light
    CHIKAHISA Tomoya, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 02 Mar. 2010, Japanese
    The possibility of new biological measurement by time resolved analysis of the optical backscattering enhancement was pursued. Through simulation analysis for various optical parameter changes, the extinction time of the enhancement peak was selected as an index to evaluate the scattering property of the turbid medium such as an animal tissue. The effectiveness of this index was verified in experiments. The range of measurable depth in a scattering medium was analyzed. The results with our experimental system suggested that we can measure the scattering coefficient up to 5 mm depth from the...
  • Fundamental study for realization of data transmission using scattered light in human body
    KAKITA Shun, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 02 Mar. 2010, Japanese
    To realize new optical communication through a human body, the feasibility of data transmission using diffusely scattered light in a human body was examined. Transmissible range of optical data in the human maniphalanx was measured. The data transmission through about 100 mm distance was possible with our experimental system. To overcome the problems of the noises, multipath transmission, and the cut of transmission paths, the space diversity (SD) method was applied to stabilize the data communication. In simulation, the effectiveness of the SD method was confirmed. For the SD method, diffe...
  • Development and application of scattering suppression technique using weakly diffused light for transillumination imaging of biological body
    KAKINUMA Hiroyuki, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 02 Mar. 2010, Japanese
    To realize a technique applicable to thicker body, the effectiveness of a transillumination imaging using weakly diffused light was examined in experiments. The possibility to extract the weakly diffused component from strongly diffused light was clarified in spatial and temporal analyses. Apparent improvement of transillumination images was demonstrated with a model phantom and a biological specimen. A technique to estimate the depth of an absorber in disuse medium was newly developed. The stability of the depth estimation technique and its applicability to animal tissue were verified in e...
  • Development of estimation technique for tissue oxygen saturation distribution by time-resolved measurement of backscattered light using multi-wavelength light
    YOSHIMURA Hitoshi, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 02 Mar. 2010, Japanese
    To realize functional imaging by time-resolved measurement of backscattered light, a technique has been developed to estimate the spatial distribution of tissue oxygen saturation. In theoretical analysis on the estimation error, the measurement conditions to suppress the error were clarified. The effectiveness of the proposed technique was verified in the Monte Carlo simulation with the three-layer model that simulates the hemoglobin concentrations of the cerebral gray matter and the thigh muscle. The noise tolerance of the proposed technique in solving an inverse problem was evaluated. In ...
  • Development of measurement techniques for scattering and absorption coefficients in diffuse scattering medium : For optical transillumination imaging of biological body
    SHIMIZU Koichi, NAMITA Takeshi, KATO Yuji
    電気学会研究会資料. LAV, 光応用・視覚研究会, 02 Feb. 2010, Japanese
  • Experimental verification for scattering coefficient estimation by time-resolved measurement of backscattered light
    KAWASHIMA Masayuki, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 21 Jan. 2010, Japanese
    We developed a technique to estimate the reduced scattering coefficient (μ_s') of turbid medium by the time-resolved measurement of backscattered light, and verified its feasibility in simulation. Here, we examined the accuracy and the characteristics of the proposed technique in experiments. The estimated values agreed well with those measured by a conventional technique and with those reported by references. The effect of absorption inhomogeneity on μ_s' estimation was investigated. The term that represents the estimation error was successfully separated in the equation of μ_s' estimation...
  • New Technique to Estimate Scattering Coefficient by Time-Resolved Measurement of Backscattered Light　　　　　　　　　　　　　　　
    Masayuki Kawashima, Takeshi Namita, Yuji Kato, Koichi Shimizu
    Biomedical Optics, OSA Technical Digest (CD), 2010, English, Oral presentation
  • Application of Dynamic Light Scattering to LDL Measurement : Attempt for quantitative evaluation of small dense LDL
    TRIRONGJITMOAH Suchin, SAKURAI Toshihiro, NISHIBATA Yuka, NAMITA Takeshi, KATO Yuji, IINAGA Kazuya, CHIBA Hitoshi, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 19 Jun. 2009, English
    The amount of small dense low density lipoprotein (sdLDL) is known to have high correlation with coronary diseases. To realize a practical quantitative evaluation of sdLDL, we applied the dynamic light scattering (DLS) technique. Three methods were newly developed to estimate the sdLDL fraction in the total LDL using the mean size or the autocorrelation function of the scattered intensity obtained in the DLS measurement. The mathematical solutions for sdLDL fraction were derived in a closed form. The feasibility of the proposed technique was verified in the experiments using latex standard ...
  • Attempt for reconstruction of tomographic image by transcutaneous fluorescent imaging
    SHIDA Genki, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 04 Mar. 2009, Japanese
    A new technique was developed to obtain the CT image for the fluorescent material in a biological body. Fluorescent images blurred by scattering are obtained at the body surface from all the circumferential directions. Deblurred images are restored using the depth-dependant point spread function. A CT image can be reconstructed using the deblurred images by the filtered back projection method. The feasibility and the effectiveness of the proposed technique were verified in the simulation and the experiments with a model phantom and a biological sample.
  • Fundamental study for next generation vein-authentication by reflection-type transillumination image of blood vessels
    AMAI Kenji, TAKAGI Kazuto, KATO Yuji, AMANO Kazuhiko, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 04 Mar. 2009, Japanese
    To realize next-generation actionless personal authentication, fundamental study was conducted to develop a wearable sensor for vein authentication. A transillumination image of blood vessels was obtained in a circular light source of epi-illumination. The major inhomogeneity over the total view area could be compensated by the attenuation filter designed from the diffusion theory. The effect of discrete light sources and the image processing for local inhomogeneity were investigated. Through this study, we could obtain the transillumination image of sufficient quality for vein authentication.
  • Basic study for scattering and absorption measurement of diffuse medium by Doppler optical coherence tomography
    NEMOTO Tomoyuki, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 04 Mar. 2009, Japanese
    For the measurement of the functional information in a biological body such as the oxygenation of the blood in the blood vessel in vivo, a technique was developed to measure scattering and absorption characteristic of flowing scattering medium by Doppler OCT principle. The intensity of the Doppler signal caused by the blood flow is measured in the spatially resolved measurement of OCT. We can estimate the optical characteristics of the blood from the attenuation of this signal with the distance in the depth direction. The concentration of an absorbing component in the blood can be also esti...
  • Fundamental study on optical tomographic imaging for small experimental animals
    TANAKA Yoshinori, KITAMA Masataka, ARISAWA Junji, TAKAGI Kazuto, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 16 Jan. 2009, Japanese
    A fundamental study was conducted on the tomographic imaging using near-axis scattered light for small experimental animals. We velified the feasibility of CT imaging by extracting the near-axis scattered light using the optical difference principle. We showed that the quantitative CT imaging of absorption distribution is possible. The spatial resolution of CT images obtained with our experimental system was evaluated as about 1mm.
  • 二波長画像演算による静脈透視像改善の試み
    北山敬士, 高木一人, 加藤祐次, 清水孝一
    日本生体医工学会大会プログラム・論文集(CD-ROM), 2009, Japanese
  • 体内蛍光像経皮イメージングによる断層像再構成の試み(II)―提案手法の実験的検証―
    志田元毅, 加藤祐次, 清水孝一
    日本生体医工学会大会プログラム・論文集(CD-ROM), 2009, Japanese
  • 多波長を用いた後方散乱光時間分解計測による組織酸素飽和度の推定
    吉村仁志, 浪田健, 加藤祐次, 清水孝一
    日本生体医工学会大会プログラム・論文集(CD-ROM), 2009, Japanese
  • 生体光散乱における後方散乱強調現象の時間特性解析
    近久智哉, 浪田健, 加藤祐次, 清水孝一
    日本生体医工学会大会プログラム・論文集(CD-ROM), 2009, Japanese
  • Effect of imaginary layer division in diffuse optical tomography using backscatterd light　　　　　　　　　　　　　　　
    Takeshi Namita, Yuji Kato, Koichi Shimizu
    The 4th Asian and Pacific Rim Symposium on Biophotonics, 2009, English, Oral presentation
  • xtraction of Weakly Scattered Light of Transillumination Imaging　　　　　　　　　　　　　　　
    Kazuto Takagi, Hiroyuki Kakinuma, Yuji Kato, Koichi Shimizu
    The 4th Asian and Pacific Rim Symposium on Biophotonics, 2009, English, Oral presentation
  • CW Detection of Weakly Scattered Light for Transillumination Imaging of Thick Body　　　　　　　　　　　　　　　
    Kazuto Takagi, Hiroyuki Kakinuma, Yuji Kato, Koichi Shimizu
    The 3rd International Conference on Bioinformatics and Biomedical Engineering, 2009, English, Oral presentation
  • Feasibility of transcutaneous data transmission using scattered light
    SAITO Toshihide, KAKITA Shun, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 06 Mar. 2008, Japanese
    For advanced data communication from implanted device, a fundamental study was conducted on the information transmission inside a biological body using light. To examine the effect of strong optical scattering inside the body, the frequency bandwidth for data transmission was evaluated. In the experiment using meat, the possibility of the transmission up to 100MHz was confirmed. To expand the bandwidth, various signal processing techniques were compared. With the linear equalizing process, we can transmit an 800MHz square wave signal. It was confirmed that 900Mcps transmission becomes possi...
  • Time-resolved analysis of optical backscattering enhancement
    KUBO Yoshihiro, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 06 Mar. 2008, Japanese
    The backscattering enhancement has been studied with continuous light. We attempted the time-resolved analysis for this phenomenon. It was newly found that the width of the backscattering enhancement peak becomes narrower as time goes in the rising time of the time-resolved backscattering pulse from diffuse scattering medium. In the falling time of the backscattering pulse, the backscattering enhancement peak disappears as the time goes. We can evaluate the multiple-scattering characteristics of a sample by measuring the extinction time of the peak. Using latex beads and the Intralipid susp...
  • Depth-selective imaging of scattering medium using multiple circular light sources
    Goto Yasuo, Kato Yuji, Shimizu Koichi
    IEICE technical report. ME and bio cybernetics, 06 Mar. 2008, Japanese
    To realize a simple depth-selective imaging of diffuse medium, a new technique was developed that uses multiple circular light sources, an imaging device, and image subtraction process. If the position of a light source on the body surface changes, the propagation region of scattered light in the body becomes different. The proposed technique detects this difference by image subtraction. In the simulation based on the diffusion theory, the effectiveness of the technique was confirmed. Using a model phantom, the applicability of the technique to mammalian tissue was verified. The possibility...
  • Development of estimation technique for scattering coefficient by time-resolved measurement of backscattered light
    KANAZAWA Rui, NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 18 Jan. 2008, Japanese
    A technique was developed to estimate the scattering coefficient of diffuse medium such as a biological body by the time-resolved measurement of backscattered light. The effectiveness of the technique was confirmed in the Monte Carlo simulation. In the analysis of measurement noise, appropriate conditions of the measurement were obtained. The effect of the inhomogeneity of the absorption coefficient was investigated. The possibility to suppress the effect was demonstrated. In the case of an inhomogeneous scattering coefficient, the meaning of the time-dependent estimated value was clarified.
  • CT imaging of diffuse medium by time-resolved measurement of backscattered light – Evaluation of spatial resolution with biological tissue –　　　　　　　　　　　　　　　
    Takeshi Namita, Yuji Kato, Koichi Shimizu
    6th International Conference on Optics-photonics Design & Fabrication(CD-ROM), 2008, English, Oral presentation
  • Attempt at tomographic imaging of biological body by time-resolved measurement of backscattered light
    NAMITA Takeshi, KANAZAWA Rui, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 22 Jun. 2007, Japanese
    A technique has been developed to obtain tomographic image of scattering object by the time-resolved measurement of backscattered light. In this technique, the object was divided into a few hypothetical layers. To increase the number of the layers, we proposed a new technique based on repetitive estimation processes. The effectiveness of the proposed technique was confirmed using a model phantom with known structure. We could estimate the absorption distribution up to 7mm depth from the surface. The applicability of the proposed technique to real biological tissue was examined experimentall...
  • Fundamental study of reflection-type transillumination imaging for biometrics identification
    Matsubara Shinichi, Takagi Kazuto, Kato Yuji, Amano Kazuhiko, Shimizu Koichi
    IEICE technical report. ME and bio cybernetics, 09 Mar. 2007, Japanese
    For the application to biometrics idenfitication, a fundamental study was conducted on the reflection-type transillumination imaging that is applicable to thick biological tissue. An inhomogeneous attenuation filter was designed to compensate the inhomogeneity in the transillumination image. With this filter, the intensity resolution was improved 8 times higher and the field of view was enlarged more than 4 times larger. Considering the variation of scattering and absorption characteristics among subjects, an inhomogeneous attenuation filter was manufactured. With this filter, transillumina...
  • Detection of local ultrasound-modulated signal in homogeneous scattering medium by optical interferomety
    Endo Tomoki, Kato Yuji, Shimizu Koichi
    IEICE technical report. ME and bio cybernetics, 09 Mar. 2007, Japanese
    For the optical measurement in a scattering medium, a fundamental study was conducted on the combination of the ultrasonic modulation and the low-coherence optical interferometry. We have succeeded to detect the optical signal from the focal point of ultrasound in an optical scattering medium without using the reflecting object such as mirror. Using this optical signal, we showed the possibility of the absorption measurement in a scattering medium and clarified the application limit of this technique. Based on these results, we attempted the imaging of the absorption distribution in a scatt...
  • Improvement in extraction of near-axis scattered light by controlling light propagation for transillumination imaging of biological bodoy
    BETTOYASHIKI Genta, TAKAGI Kazuto, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 09 Mar. 2007, Japanese
    For transillumination imaging of biological body, the previously proposed technique was improved to extract near-axis scattered light efficiently. In experiments, it was verified that extraction efficiency can be improved about 10dB using the newly proposed technique. It was confirmed that the propagation area of scattered light can be largely restricted to the near-axis region. In the measurement of absorption distribution in scatterers, the possibility of accurate absorption measurement with good spatial resolution was demonstrated.
  • Detection of ultrasonic modulation in optical scattering medium using optical interferometry
    ENDO Tomoki, KATO Yuji, SHIMIZU Koichi
    電気学会研究会資料. LAV, 光応用・視覚研究会, 12 Jan. 2007, Japanese
  • Improvement of Transcutaneous fluorescent imaging
    ITAGAKI Hidenobu, KOIZUMI Ruriko, KATO Yuji, SHIMIZU Koichi
    電気学会研究会資料. LAV, 光応用・視覚研究会, 12 Jan. 2007, Japanese
  • Attempt to suppress optical scattering for transillumination imaging of biological body
    TAKAGI Kazuto, BETTOYASHIKI Genta, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 18 Sep. 2006, Japanese
    Due to the strong scattering of biological tissue, a beam of light propagates in an off-axis area in the body. This makes the spatial resolution of the transillumination image significantly poor. To solve this problem, we propose a new technique to suppress this effect of scattering. By controlling the light propagation path in a scattering medium, we can obtain the near-axis component of the incident light beam. In experiments, the feasibility of the proposed principle was confirmed and the effectiveness was verified using a model-phantom of a biological body.
  • 12.生体透視イメージング性能向上のための散乱光成分抑制の試み(平成17年度北海道支部大会抄録)
    高木 一人, 加藤 祐次, 清水 孝一
    生体医工学 : 日本エム・イー学会誌, 10 Jun. 2006, Japanese
  • Fundamental study for transcutaneous fluorescent imaging
    KOIZUMI Ruriko, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 21 Jan. 2006, Japanese
    The image observed at the body surface is deteriorated due to the strong scattering of the body tissue. To solve this problem, a fundamental study was conducted. It was confirmed that the image was improved effectively by the deconvolution with the theoretically derived point spread function (PSF). It was effective only when the depth of the fluorescent source was known a priori. We have developed a new technique to estimate the depth of the fluorescent source in the deconvolution with the derived PSF. With this technique, we can recover the correct image of the fluorescent source from the ...
  • Tomographic imaging of scattering object by time-resolved measurement of backscattered light : Fundamental study for practical application
    NAMITA Takeshi, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 23 Mar. 2005, Japanese
    A technique has been developed to obtain tomographic image of scattering object by the time-resolved measurement of backscattered light. A fundamental study was conducted to make the proposed technique practicable. The estimation error could be reduced less then half by increasing the optical power of the ultra-short pulse-laser by 100 times. The feasibility of stable CT imaging was verified by stabilizing the object. The results of this experimental study suggest that the problems of the proposed technique are not essential and that they can be technically overcome.
  • Attempt for limiting propagation path in light scattering medium using two ultrasonic transducers
    WATANABE Eijiro, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 23 Mar. 2005, Japanese
    For the measurement of NIR absorption distribution in a biological body, a new technique to use the interaction of light and ultrasound has been devised. In this technique, we provide a plural number of ultrasonic modulation regions in the scattering medium in which light propagates. Using the modulation frequency, we can selectively detect the light which passed along the straight line between the modulation regions. In experimental study, the feasibility of the proposal technique was verified. In the absorption measurement, the possibility to suppress the scattering effect was demonstrated.
  • Attempt for scattering suppression for transillumination imaging of biological body
    TAKAGI Kazuto, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 23 Mar. 2005, Japanese
    For practical transillumination imaging of biological body, we have to suppress the scattered component in transmitted light. With the previously proposed technique, mechanical scanning was necessary to obtain 2-dimensional transillumination images. We propose a new technique to eliminate this mechanical scanning. We can suppress the scattered component in the transmitted light by the weighted subtraction of the image after the scattering-increase from the image before the scattering-increase. Using a scattering plate, we can apply this technique to an animal body. The feasibility was verif...
  • Extraction of ultrasonic modulation in optical scattering medium using optical interference technique
    TAKAHARA Shusaku, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 10 Mar. 2004, Japanese
    Fundamental study was conducted to obtain structural and functional information in a biological body using light and ultra-sound. The low coherence interferometry technique was applied to suppress the effect of the optical scattering between the modulated point and light incidence/output points. The characteristics of a measurement system and the delectability of the modulated signal by the proposed method were investigated. It was shown experimentally that the detectable depth of the modulated signal increased with the increase of the coherence length of a light source. In a phantom experi...
  • Analysis of Spacio-Temporal Characteristics of Light Scatterig in Biological Medium
    Shimizu Ken, Kto Yuji, Shimizu Koichi
    IEICE technical report. ME and bio cybernetics, 10 Mar. 2004, Japanese
    For transillumination of small animal and near-surface imaging of animal body, fundamental study was conducted on the light propagation in random media. Through the measurement of attenuation, degree of polarization and coherency, it was found that the effect of multiple scattering appeared in the biological tissue with the thickness of more than 1-3 mm. Since the conventional solution of the diffusion equation is not applicable in this scattering region, new solution was derived from the equation of transfer by applying the small angle approximation. The reasonability of the solution was v...
  • Detection of ultrasonic modulation effect in back-scattered light using interference technique
    WATANABE Hiromu, TAKAHARA Shusaku, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 11 Mar. 2003, Japanese
    Fundamental study was conducted to obtain structural and functional information in a biological body using light and ultrasound. When we use the light modulated the light by ultrasound, a technique is required to extract the information of the modulated position from received light. Based on the principle of optical coherence tomography(KOCT), we propose a technique to detect the light component which has propagated along the straight line between the two points of ultrasonic modulation and light incidence/detection. An experimental system was constructed, and the detectability of the ultra...
  • Transcutaneous imaging of biological information using fluorescent contrast medium
    TOCHIO Koji, TAKA Yoshinori, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 11 Mar. 2003, Japanese
    To realize reflection-type transcutaneous fluorescent imaging, a fundamental study was conducted. The degree of image degradation due to scattering was investigated. The degradation can be improved by the deconvolution using a point spread function(PSF). The fluorescent image of a known object was measured and the PSF was obtained as a function of the object-depth. In a model experiment, the effectiveness of this technique was examined. The visible depth in a scattering medium became almost twice as deep using the depth-depended PSF. The usefulness of this technique was demonstrated in the ...
  • Estimation of depth distribution of absorption by time-resolved measurement of backscattered light
    AKIYAMA Koji, NISHIDA Yohei, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 11 Mar. 2003, Japanese
    A fundamental study was conducted to realize CT imaging using backscattered light. To estimate the depth-distribution of absorption, a temporal pathlength distribution (TPD) in a scattering object is required. The TPD has been obtained in computer simulation. In this study, we proposed a technique to obtain the TPD in a real measurement. In the experiment using three-layer model phantoms, the effectiveness of the proposed technique was verified. The possibility of CT imaging was demonstrated in the reconstruction of a cross-sectional image of an absorber in a scattering object.
  • Absorption Imaging in Optically Turbid Medium Using Spacio-Temporal Technique
    OKAMOTO Yasushi, KITAMA Masataka, MISAWA Kenji, ARISAWA Junji, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 21 Nov. 2002, Japanese
    Optical imaging of biological tissue has been difficult due to strong scattering. To realize the imaging with near-axis scattered light, we have applied the scattering-angle differential technique and the time-resolved measurement technique to the quantitative CT imaging in a turbid medium. We used a model phantom which contained a cylindrical structure with a coaxial absorption layer. CT images were reconstructed with the proposed technique and compared with those obtained with the conventional collimation technique. The spatial resolution and the accuracy of absorption were improved signi...
  • Attempt of reconstruction of absorption distribution in body using backscattered light
    KATO Y, AKIYAMA K, SHIMIZU K
    生体・生理工学シンポジウム論文集, 09 Sep. 2002, Japanese
  • Fundamental study for functional measurement inside the body using near-axis scattered light : Detection by time-resolved measurement and comparison with time-gating technique
    SATO Fumihiko, SASAKI Toshikazu, KATO Yuji, SHIMIZU Koichi
    生体・生理工学シンポジウム論文集, 09 Sep. 2002, Japanese
  • Detection of near-axis scattered light using time-resolved subtraction technique : Fundamental study of scattering measurement for optical CT
    SATO Fumihiko, SASAKI Toshikazu, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 11 Mar. 2002, Japanese
    The detectability and the usefulness of the near-axis scattered light using differential time-resolved method was investigated. The efficient detection of the near-axis scattered light by the proposed technique was confirmed in the examination of the temporal and the spatial characteristics of the detected light. In the absorption measurement of inhomogeneous scatterer, the possibility and the error of the μ_a estimation was shown in comparison with the time-gatng method. The CT image obtained by the proposed technique was superior to those by the time-gating method in the spatial resolutio...
  • Measurement of path-length distribution for reconstruction of absorbance distribution by using back-scattered light
    KATO Y, AKIYAMA K, SHIMIZU K
    レーザー学会学術講演会年次大会講演予稿集 = Annual meeting of the Laser Society of Japan digest of technical papers, 01 Jan. 2002, Japanese
  • Fundamental study for estimation of absorption distribution in a body using backscattered light
    AKIYAMA Koji, KATO Yuji, SHIMIZU Koichi
    電気学会基礎・材料・共通部門大会講演論文集 = Proceeding of Annual Conference of Fundamentals and Materials Society, IEE Japan, 21 Sep. 2001, Japanese
  • Estimation of absorption distribution in scattering medium using backscattered light
    SHIMIZU K, HORIE H, AKIYAMA K, KATO Y
    レーザー学会研究会報告 = Reports on the Topical meeting of the Laser Society of Japan, 07 Sep. 2001, Japanese
  • Effect of ultrasound irradiation on impulse response of backscattered light
    YAMAOKA M, KATO Y, SHIMIZU K
    IEICE technical report. ME and bio cybernetics, 15 Mar. 2001, Japanese
    For the reconstruction of absorption distribution in biological tissue, the application of ultrasound was proposed. The effect of the refraction-index change caused by ultrasound irradiation on the impulse response (time-resolved pulse shape) of backscattered light was investigated in a simulation study. It was found that the peak-time and the peak-magnitude of the impulse response were varied by the ultrasound irradiation on a scattering object. The relation between these variations and the wavelength/phase of ultrasound was clarified. It was also found that the optical path-length distrib...
  • Analysis of light scattering in biological tissue for transillumination imaging : Derivation and evaluation of point spread function using small-angle approximation
    Fujiwara Isao, Taka Yoshinori, Kato Yuji, Shimizu Koichi
    IEICE technical report. ME and bio cybernetics, 15 Mar. 2001, Japanese
    For transillumination imaging of biological body, image degradation in scattering medium was investigated. The small-angle approximation was applied to the transfer equation to describe the light propagation in scattering medium. As an analytical solution, the point spread function (PSF) was obtained in a closed form for the case of plane-wave incidence and a Gaussian scattering pattern. The solution could well describe the spread of the PSF. To examine the reasonability of the solution, experiments were conducted to measure the PSF through scattering medium. The measured results agreed wel...
  • Development of reconstruction technique for absorption distribution in biological tissue using backscattered light
    Horie Hirobumi, Kato Yuji, Shimizu Koichi
    IEICE technical report. ME and bio cybernetics, 15 Mar. 2001, Japanese
    For the crosssectional imaging of a biological body, a technique has been developed to reconstruct absorption distribution using time-resolved backscattered light. In this technique, we estimate the absorption distribution quantitatively by applying the operator made from a path-length distribution. In a simulation, the layered absorption distribution of a biological model was reconstructed. The reconstructed distribution agreed well with the given distribution, and the effectiveness of the proposed technique was verified. The stability of the solution in solving the inverse problem was con...
  • Basic study for transillumination imaging of biological functions using near-infrared light
    TAKA Yoshinori, KATO Yuji, SHIMIZU Koichi
    レーザー学会研究会報告 = Reports on the Topical meeting of the Laser Society of Japan, 12 Nov. 1999, Japanese
  • Detection of near-axis scattered light using time-resolved measurement technique
    TAKAGI Kentaro, KATO Yuji, KITAMA Masataka, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 18 Mar. 1999, Japanese
    In the transmitted light through scattering mammalian tissue, there should be a component which traveled along the optical axis of incident light beam. To separate this near-axis scattered light, we have introduced a time-resolved measurement technique to the previously developed spatially differential technique. With this technique, we can accurately determine the weighting coefficient for the differential process. In addition, we can estimate the increase of the pathlength in near-axis scattering. Through experimental study, the effectiveness of this technique was verified, and the useful...
  • Analysis of intensity modulated light in frequency domain for measurement of absorption distribution in turbid media
    YAMAZAKI Kinya, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 18 Mar. 1999, Japanese
    With intensity-modulated CW light, the same analysis is possible as the time-resolved technique for the scattering phenomena in mammalian tissues. Mainly in simulation, we analyzed the frequency response of scattering medium with inhomogeneous absorption coefficient. Two models were analyzed, i.e. a transmission-type and a reflection-type. In practical conditions, the frequency response of the reflection-type was more sensitive to the absorption change than that of the transmission-type. In the reflection-type, it was found that the frequency response was sensitive to the positions and the ...
  • Experimental Study for Functional Imaging with Optical Coherence Tomography
    IKEYA Masao, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 19 Mar. 1998, Japanese
    Fundamental stydy was conducted for the functional imaging with the OCT technique. The possibility of imaging with the spatial resolution of 17μm was confirmed. The interference signals were measured at the surfaces with different scattering and absorption coefficients. The following facts were found. The signal intensity does not depend largely on the change in a scattering coefficient. We can detect the surface of different absorption coefficients, and measure the change in an absorption coefficient. With the developed system, the surface of a light-absorbing object was visualized in a sc...
  • Cross-sectional imaging of absorption distribution in biological tissue using backscattered light : Development of reconstruction technique for absorption distribution
    AWATA Aki, KATO Yuji, SHIMIZU Koichi
    IEICE technical report. ME and bio cybernetics, 31 Jan. 1998, Japanese
    A technique was developed to reconstruct the cross-sectional image of the absorption distribution in a diffuse medium using backscattered light. With this technique we can get physiological information such as hemoglobin oxygenation in the body noninvasively. In this technique, we illuminate an object with an ultra-short pulse, and measure the time-resolved pulse shape of the light backscattered from the object. The absorption distribution of the scattering object can be estimated using the path-length distribution of photons at each detection time and the intensity of backscattered light a...
  • Optical data transmission between medical devices using spread spectrum technique : Attempt of multichannel transmission using indirectly scattered light
    TOYA N, KATO Y, SHIMIZU K
    IEICE technical report. ME and bio cybernetics, 17 Mar. 1997, Japanese
    To realize the wireless integration of many medical equipments, a fundamental study was conducted. The possibility of multichannel data-transmission using a spread spectrum technique and indirectlight communication was investigated. Instead of ASK, PSK was used for the primary modulation. For the error control, ARQ technique was introduced. The input level of a SAW convolver was stabilized with an AGC circuit. With these improvements, the data transmission became possible even in the condition with a negative CNR. In ECG transmission, the quality was satisfactory even when the CNR is close ...
  • Attempt to improve visibility in light scattering medium
    HIRAYAMA T, KATO Y, SHIMIZU K
    IEICE technical report. ME and bio cybernetics, 17 Mar. 1997, Japanese
    To improve the visibility in a scattering medium, a new technique was developed which suppresses the effect of scattering by averaging out the randomness of scattering. First, the degree of the improvement was investigated by quantifying the visibility. The effectiveness of this technique was verified in the imaging of the structure behind various scattering objects. In practical use, this technique can be used with a pair of collimated light source and detector in a rotate-translate mode. The possibility of this mode was demonstrated.
  • Time-resolved analysis of optical scattering in biological tissues using CW light
    HARADA T, KATO Y, SHIMIZU K
    IEICE technical report. ME and bio cybernetics, 17 Mar. 1997, Japanese
    For the analysis of light propagation in scattering random media, a technique was developed which enables us to reconstruct a time-resolved pulse-shape using intensity modulated CW light. A measurement system was developed, and the feasibility of this technique was verified experimentally. Using the medium with different scattering and absorption coefficients, time-resolved pulse shapes were reconstructed. The reasonability of the result was ascertained in the comparison with the pulse-shapes measured in a time-domain.
  • Characteristics of Polyimide Coated Silver Hollow Glass Waveguide for Er:YAG Laser
    Suzumura Masato, Kato Yuji, Miyagi Mitsunobu
    Proceedings of the IEICE General Conference, 06 Mar. 1997, Japanese
    Er:YAGレーザは光を含む電磁波の中で水に対する吸収が最も大きいということから, 歯科無痛治療等の医療分野で大きく注目されている。筆者等は, このEr:YAGレーザ光用の伝送路としてポリイミド樹脂内装銀中空ガラス導波路の開発を行ってきている。今回, 導波路の長さをこれまでの1 m程度から2 m程度と長尺にして製作を行い, その伝送特性の測定を行った。また, 導波路の機械強度の評価も行ったので, 併せて報告する。
  • Optical Transillumination Imaging of Biological Body
    SHIMIZU Koichi, KATO Yuji, YAMAMOTO Katsuyuki
    レーザー学会学術講演会年次大会講演予稿集 = Annual meeting, of the Laser Society of Japan digest of technical papers, 01 Jan. 1997, Japanese
  • Trans-Body Imaging with Light
    SHIMIZU Koichi, KATO Yuji, YAMAMOTO Katsuyuki
    レーザー学会研究会報告 = Reports on the Topical meeting of the Laser Society of Japan, 25 Jul. 1996, Japanese
  • Fabrication of Polyimide-coated Silver Hollow Glass Waveguides for Er : YAG Laser
    SUZUMURA Masato, WANG You, KATO Yuji, HONGO Akihito, MIYAGI Mitsunobu
    レーザー学会研究会報告 = Reports on the Topical meeting of the Laser Society of Japan, 25 Jul. 1996, Japanese
  • Fundamental study to obtain in vivo functional information using backscattered light : Application of low-coherence light interferometry
    Takaya J, Kitama M, Kato Y, Shimizu K, Yamamoto K, Kaneko M
    IEICE technical report. ME and bio cybernetics, 19 Mar. 1996, Japanese
    A fundamental study has been conducted on the applicability of low-coherence interferometry to the functional CT imaging of biological tissues with light. First, we examined the effectiveness of the proposed technique to suppress the scattering component in the transmitted light. Then, it was shown that we could estimate the absorption coefficient of a scattering medium even in the strong scattering like in a living tissue. Finally, this technique was applied to a rat blood. Using two different wavelengths of light, we could detect the local change in the redox state of the blood.
  • Optimization of Fablication Condition for Silver-Hollow Glass Waveguides
    Kubota Satoshi, Kato Yuji, Akama Yosuke, Miyagi Mitsunobu
    Proceedings of the IEICE General Conference, 11 Mar. 1996, Japanese
    赤外域に発振波長を持つ高出力レーザ光の伝送路として、石英キャピラリーチューブ内に銀層並びに有機樹脂薄膜を有する、誘電体内装中空導波路が提案されている。銀層の成膜には簡便な銀鏡反応が用いられているが、銀中空導波路の特性は誘電体内装後の伝送路の特性に大きな影響を及ぼす。本報告では、光学特性の測定及びSEMによる銀中空導波路の内面観察から、銀中空導波路製作の最適条件について報告する。
  • Fabrication of Polyimide-Coated Silver Hollow Glass Waveguides for the Infrared Laser
    SUZUMURA Masato, KATO Yuji, SHIMOMURA Takehiro, MIYAGI Mitsunobu
    レーザー学会学術講演会年次大会講演予稿集 = Annual meeting, of the Laser Society of Japan digest of technical papers, 01 Jan. 1996, Japanese
  • Fabrication of FCP-Coated Silver Hollow Glass Waveguides for Infrared Laser Light Transmission
    WANG You, KATO Yuji, SHIMOMURA Takehiro, MIYAGI Mitsunobu
    レーザー学会学術講演会年次大会講演予稿集 = Annual meeting, of the Laser Society of Japan digest of technical papers, 01 Jan. 1996, Japanese
  • Hollow Waveguides for Infrared Laser
    KATO Yuji, MIYAGI Mitsunobu
    レーザー学会研究会報告 = Reports on the Topical meeting of the Laser Society of Japan, Aug. 1995, Japanese
  • Loss Characteristics of Fluorocarbon Polymer-Coated Silver Hollow Glass Waveguides with Small Diameter
    Osawa M, Kato Y, Miyagi M, Abe S, Aizawa M, Onodera S
    Proceedings of the IEICE General Conference, 27 Mar. 1995, Japanese
    Er:YAGレーザ等の高出力赤外レーザ光は医療分野、工業加工分野においての応用が盛んに進められている。それらレーザ光をフシキシブルかつ高効率に伝送する装置として誘電体内装中空導波路が研究されており、筆者らはガラスキャピラリーチューブ内面に銀鏡反応及び弗素樹脂(FCP)のDip-coatingによりFCP内装銀中空ガラス導波路(FCP/Ag導波路)を製作している。本論文において、銀鏡反応による銀チューブ製作の再現性の向上及び低損失化、また製作したFCP/Ag導波路の損失波長特性、及びEr.YAGレーザ光伝送特性について報告する。
  • Loss Characteristics of Polyimide-Coated Silver Hollow Glass Weveguides for Er : YAG Laser Light
    KATO Y, OSAWA M, KUBOTA S, MIYAGI M, ABE S, AIZAWA M, ONODERA S
    レーザー学会学術講演会年次大会講演予稿集 = Annual meeting, of the Laser Society of Japan digest of technical papers, 01 Jan. 1995, Japanese
  • Fabrication of flexible polyimide-coated hollow glass waveguides for the infrared
    Kato Yuji, Ohsawa Mitsuo, Miyagi Mitsunobu, Aizawa Masaru, Abe Shin-ichi, Onodera Shinji
    Technical report of IEICE. OCS, 17 Nov. 1994, Japanese
    Polyimide-polymer coated silver hollow infrared waveguides with 700 μm inner diameter and 1 m length have been fabricated for the medical applications.By measurements of the loss spectra and loss for the Er:YAG laser light of the wave guides,it is shown that this waveguides have low-loss characteristics.The heat resisting polyimide-polymer has many advantages over other dielectrics such as non-toxicity and durability.Furthermore,by using silica capillary tube as a base tube,this waveguide is shown to be very flexible.

Courses

  • 学生実験　　　　　　　　　　　　　　　
    東北大学
  • プログラミング　　　　　　　　　　　　　　　
    北海道大学
  • 生体情報工学演習　　　　　　　　　　　　　　　
    北海道大学
  • 生体情報工学実験　　　　　　　　　　　　　　　
    北海道大学
  • 電気回路　　　　　　　　　　　　　　　
    北海道大学
  • 応用数学演習I　　　　　　　　　　　　　　　
    北海道大学
  • 工学基礎物理学I　　　　　　　　　　　　　　　
    北海道大学

Affiliated academic society

  • THE JAPAN SOCIETY OF APPLIED PHYSICS　　　　　　　　　　　　　　　
  • THE INSTITUTE OF ELECTRONICS, INFORMATION AND COMMUNICATION ENGINEERS.　　　　　　　　　　　　　　　
  • THE LASER SOCIETY OF JAPAN　　　　　　　　　　　　　　　
  • JAPANESE SOCIETY FOR MEDICAL AND BIOLOGICAL ENGINEERING　　　　　　　　　　　　　　　

Research Themes

  • Advanced non-invasive optical measurement techniques for the constant monitoring of blood lipid components
    Grants-in-Aid for Scientific Research
    01 Apr. 2023 - 31 Mar. 2026
    加藤 祐次, 清水 孝一, 松村 健太, 橋本 守
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 23K11799
  • Near-infrared light delivery in deep tissue using vivo helical optical waveguide formed by a topological ultrasound beam
    Grants-in-Aid for Scientific Research
    30 Jun. 2022 - 31 Mar. 2025
    橋本 守, 工藤 信樹, 加藤 祐次
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Research (Pioneering), Hokkaido University, 22K18436
  • 生体内拡散光を用いた無侵襲血管性状イメージングシステムの構築
    科学研究費助成事業 基盤研究(C)
    01 Apr. 2021 - 31 Mar. 2024
    北間 正崇, 清水 孝一, 加藤 祐次
    慢性腎不全患者が人工透析を行う際に造設する内シャントの血管異常（狭窄，閉塞）を早期に診断・治療することは，患者QOLの点から重要である．透析患者の狭窄原因として症例の多い血管壁の石灰化状態を無侵襲で体外からイメージングできれば，早期診断の一助となる．本研究では，従前に研究・開発してきた非侵襲内シャント光イメージング技術を応用することで血管石灰化状態のイメージング手法の確立を目指す．今年度は，前年度に検討・評価を行った最適波長光源と検出系を用いてイメージングに焦点を絞り，以下の実験的検証を行った．
    １．計測の定量性を評価するために，血管壁全体が均等に石灰化する狭窄状態を模擬した前腕部ファントムを作製した．前腕部ファントムの基本構造は従前の研究で確立しており，新たにリン酸カルシウムを基材とした石灰化狭窄部を組み込んだ．作製したファントムの構造評価にはX線透視装置を利用した．
    ２．前年度に構築した2次元分布計測システムを拡張し，波長810 nmと1,208 nmの複数光源での撮影を可能とするシステムを構築した．このシステムを用いて，前述の前腕部ファントムにおける模擬石灰化病変の描出を目指した．その結果，波長810 nmでは，血管壁部と血液部は鮮明に描出されるものの，石灰化部は透過性が高く描出されないことが示唆された．また，波長1,208 nmでは，石灰化部は高コントラストで描出されたものの，正常血管壁や血液部のコントラストが低いことが再確認された．これらの結果から，両波長での透視像を統合することにより，石灰化部，血液部の分離描出が可能となり，限定条件下ではあるが狭窄部外径が最大誤差率2.8％の精度で検出可能なことが明らかとなった．
    日本学術振興会, 基盤研究(C), 北海道科学大学, 21K12734
  • Development of new technique for localized spectroscopy in animal body using time-reverse propagation of phase-conjugate light
    Grants-in-Aid for Scientific Research Challenging Research (Pioneering)
    30 Jul. 2020 - 31 Mar. 2023
    清水 孝一, 加藤 祐次, 北間 正崇, 任田 崇吾, 犬島 浩
    本研究は、位相共役波による時間反転という新原理を散乱分光の分野に新たに導入することにより、これまで実現が困難であった強い散乱体内部における局所領域分光計測技術の開発を目的とする。第三年度の研究実績は次のとおりである。
    １．これまでの理論解析の結果をもとに、着想を具現化するための計測方法、計測条件、計測範囲等につき解析をさらに進め、問題点を明確化した。具体的には、生体のような濃厚系散乱体内部の光伝搬につき、次のように詳しい解析を行った。(1)均一散乱体に対しては、光エネルギーの輸送方程式に基づき、拡散近似解を適用して解析を行った。より具体的システムに対し、実測において必要とされる入射光量を明らかにするとともに、変調周波数、検出感度、計測系のＳＮ比、計測可能深さ等に関する問題点を特定した。 (2)血管や筋肉層など不均一な対象に検討を進め、モンテカルロ法に基づくシミュレーションにより、計測条件の特定を行った。
    ２．初年度に独自に考案したイノベーション、つまり超音波変調周波数を時間に対し掃引するチャープ方式を実用化に近づけた。具体的には、 (1) 原理解析をさらに進め、チャープ方式を組み込んだシステムの働きを、より実用レベルでシミュレーションできるようにした。その結果、(2)生体組織のような濃厚系散乱体内部において、光計測領域を局所化する性能の向上が図られた。
    ３．体内血管のモデルを構築し、位相共役波による時間反転イメージングを行った。超音波変調の部分に対し、従来法と新規チャープ方式を適用し、有意な空間分解能の向上を確認した。これに伴い、チャープ方式の利点ならびに問題点を明らかにした。
    ４．これらの成果を国際会議や国内学会で発表した。2022年度は、8回の国際会議においてのべ10件の研究発表（Plenary1件、Keynote3件、学生受賞1件）を行った。
    Japan Society for the Promotion of Science, Challenging Research (Pioneering), Waseda University, 20K20537
  • Development of transcutaneous optical measurement of blood particulate concentration for non-invasive monitoring of blood components
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    01 Apr. 2020 - 31 Mar. 2023
    加藤 祐次, 清水 孝一, 橋本 守, 松村 健太
    本研究の大きな目標である血中中性脂肪濃度の無侵襲光学計測の実現のため、計測手法は生体透過性の高い可視から近赤外の波長領域での後方散乱光の空間分解計測を基礎としている。前年度まで、計測対象の一つとしている前腕部静脈の数値モデルに対するモンテカルロ・シミュレーションにより、静脈の形状・位置に対して光源と検出器の距離を調整する必要性が分かったため、センサー配置の最適化について検討した。また、推定アルゴリズム精度のさらなる向上のため、静脈が走行していない箇所での周囲媒質のみの光学特性推定を組み合わせて、個人差や計測箇所による変動を抑えたロバスト性の向上を進めた。さらに、メディカルフォトニクス社の協力により試作機を用いて、これまで準備してきた実験ファントムを用いて実測し、シミュレーションや光拡散理論と比較検討を行った。その結果シミュレーションで検討してきた推定アルゴリズムに対して修正指針を得た。
    一方、毛細血管を対象とした光電式脈波計測法の応用について、スマートフォンアプリおよび多色のLEDとPDからなる計測モジュールを用い、前年度までの検討を踏まえて接触圧力をコントロールしつつ、脂肪食摂取前後の光電脈派信号の変化について評価した。その結果、現状では脂質濃度変化に対する光電脈波信号の変化は見出すことはできなかった。今後、脈波信号の解析について単純な信号強度の変化のみではなく、周波数解析等による解析を要することが課題となった。さらに、ハードウェア面で通常の光電脈波計測のみならず、干渉法に基づくスペックル計測法の適用等の計測法の拡張についても今後の課題とし、基礎実験データを得た。
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 20K12685
  • Exploring optimal measurement methods to exploit the high motion artifact tolerance of visible light photoplethysmographs
    Grants-in-Aid for Scientific Research
    01 Apr. 2018 - 31 Mar. 2021
    松村 健太, 山越 健弘, 加藤 祐次, 任田 崇吾
    開発中の測定装置については、安静状態であれば安定して計測を行える段階まで作成が進んだ。具体的には、光電式容積脈波の測定回路をブレッドボード上に構築し、これにチップLED(発光ダイオード)とPD(フォトダイオード)を組み合わせた自作センサーを接続した。そして、センサーLEDのチョッピング制御を行う基板上のマイクロコンピューター(mbed)と、シリアルポートを介してこれを制御するパソコン(Apple Mac)双方の自作ソフトウェアーに更なる改良を施した。これにより、反射型の青色、緑色、赤色、近赤外光脈波と、透過型の赤色、近赤外光脈波の、計6種類の脈波が同時測定可能となった。
    以上の装置を用いて予備実験を実施した。その結果、安静状態においてデータが安定して取れていることが確認された。一方で、激しい体動を加えると、理由不明のノイズが入り測定できなくなることも確認された。多角的にこの現象を検証した結果、(1) 激しい体動によって脈波センサーの固定状態が著しく悪くなる場合があること、(2) 腕に固定したコードがセンサーを引っ張ることでセンサー回路がショートしているらしいこと、が分かった。これより、引き続きセンサー部の改良、特に、センサー部分のプリント基板化が必須であることが分かった。
    一貫したデータ処理を行うため、データ解析専用ソフトウェアーを開発した。これにより、高速フーリエ変換、区間平均処理、信号ノイズ(SN)比の算出、心拍数の計算、体動アーチファクトの周期と振幅の算出、といった一連の解析を効率良く行うことが可能となった。このソフトを用いて、これまでに測定したデータのSN比を解析した結果、反射型の青色、緑色、近赤外光脈波において、高い体動アーチファクト耐性が示されていることが明らかとなった。
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), University of Toyama, 18K12070
  • Development of time-reversal measurement technique using phase-conjugate wave for noninvasive spectral analysis of animal body
    Grants-in-Aid for Scientific Research Challenging Research (Exploratory)
    29 Jun. 2018 - 31 Mar. 2020
    Koichi Shimizu
    For noninvasive spectral analysis in a human body, we attempted the development of a localized absorption measurement technique in a turbid medium by introducing a new time-reversal principle using a phase-conjugate light. The following accomplishments were achieved, and clear imaging of internal structure in a turbid medium became possible.
    (1) A new technique to generate phase-conjugate light with intensity modulation was devised. (2) An experimental system for the time-reversal phenomenon was developed and improved. (3) The scattering suppression ability of the proposed technique was evaluated. (4) The independence of the scattering suppression on the light absorption in the medium was confirmed. (5) The system performance was improved by increasing the coherent length of light source. (6) The applicability of the proposed technique to animal tissue was verified.
    Japan Society for the Promotion of Science, Challenging Research (Exploratory), Waseda University, 18K18865
  • System development to realize transillumination and functional imaging of animal body using safe light
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    01 Apr. 2017 - 31 Mar. 2020
    Shimizu Koichi
    To realize 3D transillumination imaging of internal body structure and physiological function, we integrated our principles to establish a new technique, and developed a test system. Through this study, we achieved the following results.
    (1) An inverse scattering problem was solved to obtain internal structure in a turbid medium using scattered light from the medium. (2) Blurred transillumination image could be improved by the deconvolution with a point spread function. (3) The problem of image blur was resolved using the convolutional neural network obtained by deep learning. (4) The feasibility of 3D transillumination imaging was confirmed using a tissue-simulated model phantom. (5) A test system was designed and manufactured. (6) The feasibility of functional imaging was confirmed in the identification of vein and artery in a transillumination image. (7) 3D functional transillumination imaging was achieved in animal experiments.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Waseda University, 17H02112
  • Artificial intelligence pathological diagnosis by hyperspectral nonlinear Raman scattering imaging
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    01 Apr. 2017 - 31 Mar. 2020
    Hashimoto Mamoru
    By reducing the noise of observation data and improvement of observation time using deep learning, we succeeded in the imaging rate improvement of 1.6–1.2 image/min. to 12.5-4.0 image/min. In tissue classification by machine learning of nonlinear Raman scattering images, pre-training with fluorescence images significantly improved the segmentation ability. Besides, we have developed a new microscope for acquiring a large number of hyperspectral nonlinear Raman scattering images and succeeded in increasing the speed 14 times and reducing the excitation light peak irradiance 1/12 compared to the conventional method. It was shown that hyperspectral images of cultured cells were classified by deep learning, and that unsupervised learning could classify cells with different culture conditions.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 17H02793
  • Challenge to establish diagnostic criteria for awake bruxism during daytime by multicenter research
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    01 Apr. 2017 - 31 Mar. 2020
    Yamaguchi Taihiko
    With the aim of establishing diagnostic criteria for diurnal awake bruxism (d-AB), we performed electromyography with an ultraminiature wearable electromyographic device in collaboration with multiple facilities. As a result, we were able to construct a database of daily daytime masseter muscle activity without restraint and various clinical findings in more than 150 subjects. The distribution of the number and magnitude of muscle activity was wide in both the d-AB conscious group and the d-AB non-conscious group, and the overlap between the two groups was also very large. It was shown that it was difficult to explain the amount and magnitude of daytime masticatory muscle activity only by classification of d-AB based on self-awareness.Therefore, based on the numerical distribution of the newly established database, a method of grading masticatory muscle activity during the day in several stages and using the grading as an index for d-AB evaluation was suggested.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 17H04386
  • Development of a non-invasive vascular imaging system using light to reduce the burden of dialysis patients
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    01 Apr. 2017 - 31 Mar. 2020
    Masataka Kitama
    We have developed the technique to visualize the structure of inner AV fistula with diffuse light that we have established and also developed the simple non-invasive system for the measurement of inner diameter of the artery, which is the criterion for percutaneous transluminal angioplasty (PTA) as it had traditionally depended on X-ray. We also developed the compact measurement system in order to reduce patients' mental and physical burden.
    In this system, the feasibility of depicting changes in vascular characteristics and the improvement of spatial resolution have been shown by incorporating light sources with multiple wavelengths for simultaneous measurement. The accuracy of the estimation of vessels inner diameter also improved with machine learning.
    Therefore, the effectiveness of the proposed system was demonstrated.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University of Science, 17K01418
  • Development of new technique for spectral measurement in scattering medium using time-reverse principle with phase-conjugate wave
    Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    01 Apr. 2016 - 31 Mar. 2018
    Shimizu Koichi
    We conducted this research to open a new possibility for the localized spectral measurement in a turbid medium by introducing the new time-reversal principle using a phase-conjugate wave. The following accomplishments were achieved.
    1. In theoretical analysis, we made the fundamental measurement technique to realize the proposed method clear. 2. Through repeated simulation, we optimized the function of the proposed technique. 3. We developed the measurement system to realize the time-reversal principle using the phase-conjugate light. 4. We confirmed the ability of the developed system using a model phantom of animal tissue. 5. We verified the applicability of the system to an animal body in the experiment with chicken breast meat. 6. The result of this study is published in a prestigious journal, Biomedical Optics Express of the Optical Society of America.
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Waseda University, 16K14239
  • Challenge to optical impression method of abutment-tooth under the gingiva - Application of near-infrared light diffusion simulation -
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    01 Apr. 2015 - 31 Mar. 2018
    UEDA YASUO, TAGUCHI Yuu
    We investigated the use of near infrared as a method to capture the part that can not be measured with the intraoral scanner. Instead of soft tissue, we wrapped raw ham around abutment teeth made by melamine resin. Light scattered inside the resin tooth was imaged with an infrared camera installed at a position orthogonal to the incident light axis. The margin shape of the abutment tooth was generated by analyzing the pixel value of the fluoroscopic images. But, the shape that can be generated had a error with respect to the depth direction of the image, which was considerably shifted from the original shape. In order to generate a more accurate shape, it is considered necessary to increase the amount of information, review the intensity of light, direction of irradiation and imaging direction, narrow down the search area in consideration of the shape of the preparation tools.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 15K11143
  • Pulse glucometry: Pioneering research towards practical non-invasive optical measurement of blood glucose
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    01 Apr. 2014 - 31 Mar. 2018
    Yamakoshi Ken-ichi
    According to a statement issued by International Diabetes Federation, diabetes population in 2015 runs up to 415 million people and Japan has diabetes powers ranked 9th in the world. In a diabetic patient blood glucose (BGL) measurement, most desirably non-invasive method without blood sampling, is needed to control BGL level. Unfortunately such practical non-invasive method has not yet been developed up to now.
    We have previously developed a novel non-invasive BGL measurement using a finger called “pulse glucometry” and evaluated its validity on an experimental basis. To realize technical practicability of this method, it is essential to develop a new finger-photoplethysmography (PPG) in a wavelength region with BGL absorption having quite high accuracy and sensitivity as well as convenient use. The present study was carried out focusing especially on this PPG development, aiming a basic establishment towards the world’s first non-invasive BGL measurement device for practical use.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Showa University, 26242044
  • Realization of optical transillumination imaging of 3D internal body structure by integrating new principles
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    01 Apr. 2013 - 31 Mar. 2016
    Shimizu Koichi, KUDO Nobuki, KATO Yuji, KITAMA Masataka
    To realize 3D transillumination imaging of macroscopic internal body structure, we integrated our principles to develop a new technique. Through optimization using Monte Carlo simulation, a measurement system was constructed. We analyzed the characteristics of the developed system, and necessary improvements were made. In the animal experiments, the feasibility of imaging the internal body structure with the safe near-infrared light without radio-active exposure was verified. The feasibility of functional imaging such as tissue oxygenation state was also verified.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 25282123
  • Development of the system to measure the diffuse light to depict the structure in the blood vessel
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    01 Apr. 2012 - 31 Mar. 2015
    KITAMA Masataka, SHIMIZU Koichi, NAMITA Takeshi, KATO Yuji
    We conducted a study to realize the imaging system of the blood vessel in order to detect the abnormality of the blood vessel structure in the arteriovenous fistula for hemodialysis.
    We have developed the measuring system to observe the arteriovenous structure that is non-invasive and compact utilizing the diffuse light in the body tissue positively based on our previous research on the optical bioinstrumentation. We have developed the image processing algorithm to depict the structure in the blood vessel and verified it with the experiment with the phantom. Moreover we have presented the possibility to depict the changes of the blood vessel property in combination with spectroscopic technology. Herewith, we have shown the validity of our proposed system.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University of Science, 24500513
  • Development of a new technique of three-dimensional reconstruction for simple fluorescent imaging in a living body
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    2011 - 2013
    KATO Yuji, SHIMIZU Koichi
    A simple technique was newly developed to estimate the depth and the thickness of a fluorescent object in a turbid medium, such as an animal body. In this technique, we estimate the depth and the thickness using multiple excitation light sources with multiple wavelength. We analyzed the relation between the depth and thickness of a fluorescent object and the intensity ratio of the fluorescent light, and confirmed the validity of this principle. Using this principle, we have successfully estimated both the depth and the thickness of a fluorescent object in a tissue or tissue equivalent phantoms simultaneously. Finaly, using the estimated depth, blurred images have successfully restored by decovolution with a pointspread function. Using the restored images and the estimated depth, we could construct three dimensional image of a fluorescent object in a turbid medium.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, Principal investigator, Competitive research funding, 23500509
  • Realization of transcutaneous spectral measurement at local area in biological body by new principle
    Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    2011 - 2012
    SHIMIZU Koichi, KUDO Nobuki, KATO Yuji, NAMITA Takeshi
    We conducted a study to realize the selective spectral analysis at a local area in strong scattering medium, such as biological tissues. In two years study, we have developed a technique to quantitatively measure the optical absorption at a local area in the body. This result opened the new possibility; for the non-invasive transcutaneous measurement of accurate optical absorption; and for the tissue spectral measurement while eliminating the effect of the interstitial tissue. We have reported these results in academic journals and international/domestic conferences, and applied patents.
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Hokkaido University, 23650297
  • Development of optical transillumination system to realize imaging of 3D structure using new principles
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    2009 - 2012
    SHIMIZU Koichi, KUDO Nobuki, KATO Yuji, KITAMA Masataka, CHIBA Hitoshi
    To realize 3D transillumination imaging of internal structure and function of biological body, we developed new techniques based on original principles and created the systems to verify them. In this study, the feasibility of imaging the internal structure of experimental animals and human limbs using safe near-infrared light without radio-active exposure was verified. The feasibility of functional imaging such as tissue oxygenation state was also verified.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, Coinvestigator not use grants, Competitive research funding, 21240045
  • 光散乱を積極的に利用した新たな体内通信手法および実現システムの開発
    Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    2008 - 2009
    清水 孝一, 加藤 祐次, 山下 政司, 北間 正崇
    従来、カプセル内視鏡など体内機器との通信には、電波による単純な通信方式が用いられてきた。これに対し本研究は、体内を伝搬する散乱光を積極的に用いた光通信を新たに提案し、その実現可能性を実証することを目的とする。
    体内深部からの光信号は、生体組織で散乱され広く拡散していく。体表面に装着した複数の光センサでこの信号をとらえ、体内生理情報を復元する。光散乱を積極的に利用し、体表上いくつかの点に光センサを配置することにより、死角のない常に安定した信号伝送が期待できる。
    本年度は、前年度までの検討内容を踏まえ、提案手法の基本をなす体内散乱光による信号伝送実験装置を試作すると共に、それを用いた実験により信号伝送方式の最適化を図った。具体的内容は次のとおりである。
    1.生体内・光通信システムを試作した。
    2.試作システムを用い、生体モデルファントムと生体において本手法の特性を実験的に解析した。その結果、提案手法の実現可能性が実証された。
    3.種々のダイバーシティ方式の比較などを通し、提案手法の最適化を図った。その結果、提案手法の実用における有用性が実証された。
    研究成果の発表:国際学術誌(Applied Optics 2件、Optics Express 1件)および国際会議(invited talk 2件を含め4件)において、本研究の成果を報告した。
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Hokkaido University, Coinvestigator not use grants, Competitive research funding, 20650064
  • Realization and application of transillumination imaging of biologicalbody using snake photons
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    2006 - 2008
    SHIMIZU Koichi, SHIMOOKA Toshiyuki, KATO Yuji, KITAMA Masataka, SHIMIZU Chikara
    生体の実用的な光透視実現のためには、光散乱の問題の解決が必要である。未知の点の多いsnake photonの特性を調べて生体透視へ応用することをめざし、理論的・実験的研究を行った。その結果、次の成果が得られた。イメージングに必要なsnake photonの特性を明らかにした。Snake photon の効率的な検出法を新たに考案した。実験システムを開発し、生体模擬ファントムおよび生体試料を用いたイメージングを行って、開発手法の有効性および有用性を実証した。
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, Coinvestigator not use grants, Competitive research funding, 18300145
  • Transillumination imaging of biological body using snake photons
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    2003 - 2005
    SHIMIZU Koichi, KATO Yuji, YAMASHITA Masaji, KITAMA Masataka
    For transillumination imaging of a biological body by near-infrared light, a technique has been developed to realize the imaging of absorption distribution in diffuse scattering medium. Through this study, the following results were obtained.
    (1)In theoretical and experimental analyses, it was verified that a detectable amount of snake photons is emitted through the dense medium which could not see through with the conventional technique using ballistic photons.
    (2)A technique has been developed to detect the snake photon efficiently through the scattering object which corresponds to the mammalian tissue with 10-20 mm thickness. This technique is based on the time-resolved measurement of output pulse shape for ultra-fast light-pulse incidence.
    (3)A new technique has been developed to apply the above principle to the much simpler continuous wave (CW) measurement using a CW light source.
    (4)An experimental system was newly developed which consisted of a snake-photon detection device, a model phantom to simulate the optical property of mammalian tissue and an imaging system.
    (5)The effectiveness of the proposed principle and the usefulness of the developed system were verified in the imaging experiment using the above experimental system.
    (6)The proposed principle and the developed system were applied to the transcutaneous fluorescent imaging.
    (7)An analytical solution was obtained to describe the photon propagation in a dense random medium by applying the diffusion approximation to the equation of transfer. Using this solution, a technique to improve the transillumination image through a diffusing medium was newly developed.
    (8)Through this study, a concrete measure was obtained to realize the transillumination imaging using snake photons as well as clarifying the problems to be solved.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, Coinvestigator not use grants, Competitive research funding, 15300149
  • 低コヒーレント干渉法と超音波変調法の効果的結合による生体断層撮影技術の開発
    Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
    2003 - 2004
    加藤 祐次
    生体のような高濃度散乱体おける深さ方向の光学定数分布を後方散乱光より、超音波変調法及び低コヒーレント光干渉法の機能的な結合による生体断層撮影技術開発を最終目的とする。そこで、当初の2年の研究期間内で本計測法における基礎特性の実験的検討に的を絞り、本年度は以下の事項の研究を行った。
    1.吸収分布計測の計測特性の評価
    前年度の結果を基に、散乱体に吸収体を均一に付加して実験ファントムを作成し、吸収係数の計測について実験的に評価を行った。更には、吸収分布を不均一の状態での計測を行い検証した。これにより計測システムの基礎技術確立を図られた。
    2.本計測手法の波長特性評価システムへの拡張
    生体内機能情報をより高度に取得するために、広い波長帯にわたる本手法の適用について検討を進めた。その結果より、より高機能な断層撮影技術への拡張への可能性を検討した。その結果、本手法における広帯域な波長においても本手法の有効性の確認ができた。
    3.双超音波振動子による散乱体内部光伝搬経路制限の試み
    近赤外光による生体内部吸光度分布計測をめざして、光と超音波の相互作用を利用する新たな手法を提案し、その可能性に関する基礎的検討を行った。提案手法は,散乱体内に2箇所以上の超音波変調領域を設け、それらを結ぶ直線に沿った伝搬光を選択的に検出するものである。
    Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, Principal investigator, Competitive research funding, 15700320
  • 医療のための先端的光応用技術研究の企画調査
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    2003 - 2003
    清水 孝一, 田村 守, 加藤 祐次, 山本 克之, 青柳 卓雄, 岡田 英史
    光応用技術や近代医療技術のそれぞれのレベルにおいては、わが国は先進諸国中、最高水準にある。しかし生科学における光応用技術の研究や実用化については、欧米諸国に比べ遅れていると言わざるを得ない。とくに、創造的な発想や未来を切り拓く新技術開発の多くは、国外からのものに依存しているのが現状である。これに対し、最近はわが国でも、直接医療応用をめざした光応用技術の研究が盛んになりつつある。また、世界トップレベルの先端的光応用技術を利用できる環境も、徐々にではあるが整いつつある。このような背景に対し本企画調査は、医療における光応用技術の知識体系を充実させるとともに先端的光学技術の医学・医療応用の道を拓くことをめざして、特定領域研究の準備調査を行った。
    医療のための光応用技術は、大きく基礎研究技術から臨床応用技術まで、目的別には観察・計測・診断・治療など、実に多岐にわたる。本企画調査では、これらを次の5分野に分けて調査活動を行った。すなわち、(1)光学基礎、(2)光学デバイス・装置、(3)光応用計測、(4)光応用イメージング、(5)光応用治療である。これらのうち(3)の分野については5月に、(5)の分野については7月に、(1),(2),(5)の分野については12月にそれぞれ発表会を行った。また、Optics Japan(日本光学会年次大会)の中で、パネルディスカッション「医療のための先端的光応用技術の今後を考える」(司会:研究代表者,パネリスト:すべて本研究の研究分担者)を開催し、本研究の重要性およびその成果を広く一般に公表した。さらに、わが国におけるこの分野の研究を体系的に総括し、特定領域研究形成に向けた具体的基盤とするため、選抜論文集の刊行を企画した。欧米の選抜論文集(Selected Papers)は多く存在するが、わが国のこの分野の選抜論文集は皆無に近いからである。各分担研究者の調査結果を集約し、取捨選択の後、400ページに及ぶ選抜論文集「医療のための光応用技術」を完成し、発行に至った。
    これらの活動を通し、特定領域研究の準備という本研究の主たる目的は達成されたと考える。
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, Coinvestigator not use grants, Competitive research funding, 15630006
  • 生体透過snake photonの特性解明と利用のための基礎研究
    Grants-in-Aid for Scientific Research Grant-in-Aid for Exploratory Research
    2001 - 2002
    清水 孝一, 北間 正崇, 加藤 祐次
    生体のような高濃度散乱体にビーム光を入射しコリメート受光系で検出した場合、2種類の透過光が得られる。すなわち一度も散乱を受けずに散乱体を通過した光(ballistic photon)と、前方散乱を繰り返しつつ入射光軸にまつわりつくように散乱体を通過した光(snake photon、以下SP)である。SPの発見により、これまで不可能と考えられてきたいくつかの重要な応用に新たな可能性が開かれる。本研究では、未知の点の多いSPに対し、その基礎的な特性を明らかにするとともに、その生体透視への応用ひいては光CT実現へ向け新たな可能性を拓くことを目的とした。
    本研究をとおし以下の成果が得られた。
    1.散乱体中の光伝搬に対し、輸送方程式に微小角近似および拡散近似を適用することにより理論的解析を行った。それぞれの場合の出射光の空間的・時間的特性から、SPの伝搬特性を理論的に明らかにした。
    2.散乱体内光伝搬のシミュレーションを行い、理論解析の結果の妥当性を検証した。また種々の実験条件に対するSPの特性を求めた。これらのうち実現可能な条件に対し実験システムを構築し、SPの検出可能性を実証するとともに、その特性の一端を実験的に明らかにした。
    3.SP検出に向け、いくつかの方法を試みた。それらのうち効率的にSPを検出する方法として、差動原理に基づく手法を新たに開発した。このように検出した成分が近軸散乱成分であることを確かめるため、散乱体内部に挿入したナイフエッジのイメージングを行った。その結果、検出成分が確かにSP成分であることが実験的に検証された。これらの成果は、高濃度散乱体におけるSPの検出可能性および有効な検出法を実証したものとして、国内外ともに初めてのものと考えられる。
    以上の研究により、本研究の当初の目的はほぼ達成された。今後この成果をさらに応用発展させていきたい。
    Japan Society for the Promotion of Science, Grant-in-Aid for Exploratory Research, Hokkaido University, Coinvestigator not use grants, Competitive research funding, 13878177
  • 高濃度光散乱体における音響光学特性とその光生体計測技術への応用
    Grants-in-Aid for Scientific Research Grant-in-Aid for Encouragement of Young Scientists (A)
    2000 - 2001
    加藤 祐次
    超音波技術等を導入した高性能な光生体計測技術の完成を目的として、局在的に照射された超音波による散乱粒子の振動の評価および振動周辺の光学特性の評価を中心に行った。結果は以下のようにまとめられる。
    ・低コヒーレント光干渉法による振動中心と光入出射点間の光学特性検出に関する評価
    前年度の結果を踏まえて、超音波の焦点と光の入出射点間を散乱成分を除き光軸上の光学特性を取得する手法を超音波照射と低コヒーレント光干渉法を組み合わせる方法を用いて検討を進めた。従来の低コヒーレント光干渉法で用いられる可干渉距離数10μmの光源では到達深度が小さいため、より可干渉距離の長い光源により到達深度が大きくする必要がある。本研究において、可干渉距離4mm程度のTi:Sapphireレーザを用いることを検討した。その結果、無散乱状態において、従来の光源と同様に変調信号を検出することが可能であることが明らかとなった。
    次に、現状において不明である長い可干渉距離の光源を用いた場合における、散乱係数に対する干渉強度の評価を行い、到達深度について検討を行った。その結果、干渉強度自体は可干渉距離4mmでは、数10μmの場合より散乱係数の増加に対して減衰の割合が小さいが明らかとなり、到達深度として可干渉距離4mが有利である可能性が得られた。
    以上の結果より、超音波照射と低コヒーレント光干渉法を組み合わせる方法より空間分解能mm程度、到達深度数cm程度の光生体計測法の可能性が見出された。
    Japan Society for the Promotion of Science, Grant-in-Aid for Encouragement of Young Scientists (A), Hokkaido University, Principal investigator, Competitive research funding, 12780631
  • Development of ultra-wide range biotelemetry and telemonitoring system
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    2000 - 2001
    SHIMIZU Koichi, YASUDA Kazunori, KATO Yuji, SHIMOOKA Toshiyuki, MATSUDA Seiji, YAMASHITA Masaji
    A telemetry technique and a test-system have been developed to realize continuous vital-sign monitoring for the senior citizens living alone and the patient in home care. The following research has been conducted.
    1. A ring-type sensor was designed to measure pulse-wave optically without interfering a daily activity of the subject. The telemeter using the ring-type sensor satisfied the practical demands for signal fidelity, transmission range, size, weight and battery life.
    2. A technique of two-step telemetry was newly devised to meet the antagonizing requirements for low constraint and wide coverage-area at the same time.
    3. Using a PHS terminal, an ultra-wide area telemonitoring system has been developed to realize the above technique.
    4. Using the developed system, the practicality and the usefulness of the proposed technique was tested in normal and unfavorable environmental conditions.
    Through this study, the following results were obtained. A vital-sign can be continuously monitored almost unconsciously. Usually the range of telemonitoring had been confined in a home. With this technique, the range has been expanded to the extent of almost all the domestic areas. A practical technique has been developed to monitor a vital-sign using a wearable common terminal both inside and outside the home. In the home, the cellular phone terminal serves as a cordless phone and no network charge is required. Through the experiments, the feasibility of the proposed technique and the practical usefulness of the developed system were verified.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, Coinvestigator not use grants, Competitive research funding, 12558098
  • Development of optical CT imaging system using multi-wavelength and short pulse of light
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B).
    1998 - 2000
    SHIMOOKA Toshiyuki, KATO Yuji, YAMAMOTO Katsuyuki, SHIMIZU Koichi, FUKUSHIMA Kikuro
    With a view toward the realization of an optical CT, this study was conducted to develop an advanced measurement technique to obtain physiological information using multi wavelength and ultra-short pulse of light. Through this study, the following results were obtained.
    1) A principle to suppress the strong scattering in biological tissue was developed. With this principle, we can detect a weak near-axis scattered component of light which is usually buried in a strong scattered component.
    2) A time-resolved measurement technique with an ultra-short pulse was applied to the detection of the near-axis scattered light. A technique to obtain the integral of absorption along the optical axis of the incident beam of light was developed.
    3) An experimental system was developed to use the above technique. In the experiment with this system, the absorption distribution in a scattering medium was obtained. With this technique, the spatial resolution of the reconstructed image was improved significantly. In addition, the quantitative measurement of absorption distribution became possible, which had been difficult without this technique.
    4) A principle of cross-sectional imaging using backscattered light was newly developed for the body part in which transmitted light could not be detected. To utilize this principle, a measurement technique was developed. In a simulation study, the effectiveness and the property of this technique were clarified.
    5) An experimental system was developed to use this technique. The absorption distribution in a model phantom of biological tissue was reconstructed. As a result, the reconstructed image agreed well qualitatively with the given distribution. However, further improvement was required for the quantitative measurement. It was also found that the effect of measurement error was not negligible. A new reconstruction algorithm was developed to overcome these problems by the use of multi-wavelength and ultra-short pulse of light. In the simulation and experiment, the effectiveness of this new technique was verified.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B)., HOKKAIDO UNIVERSITY, Coinvestigator not use grants, Competitive research funding, 10558125
  • Quantitative analysis and safety assessment for biological effects of ELF electromagnetic environment
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    1998 - 1999
    SHIMOOKA Toshiyuki, FUKUSHIMA Kikuro, KATO Yuji, SHIMIZU Koichi, YAMASHITA Masaji
    The first aim of this study is to establish the methods for the analysis and the evaluation of the electric field exposure to a human body. The second aim is to clarify the biological effect of electric field quantitatively using biotelemetry techniques. This study included the development of numerical analysis techniques and measurement techniques, the measurement of exposure dose in a living human body and the search for the biological effects that can be evaluated quantitatively. Through this study, the following results were obtained.
    1) We have developed a numerical analysis technique and a measurement technique of an electric field, which are applicable to a living human body. The distribution of the electric field and the induced current could be measured successfully over all parts of a human body.
    2) Using the techniques developed in the study, the electric field and the induced current were measured in the human body when it was exposed to the electric field in the instrument of an electric field therapy.
    3) We could obtain the distribution of the surface electric field and the induced current with a living human body. The results revealed the manners of the field concentration on specific parts of the body. It also revealed that the density of the induced current became high (hot spots) at some parts of the body.
    4) Through the quantitative analysis of this study, a part of the mechanism of the field perception and the cause of the individual difference in the perception level were made clear.
    5) As a physiological change caused by the electric field exposure, the phenomenon of blood flow change in a human body surface was newly discovered.
    In conclusion, the most part of the purpose of this study was accomplished, and some significant new findings were obtained.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, Coinvestigator not use grants, Competitive research funding, 10480130
  • 能動型光生体計測技術の基礎研究
    Grants-in-Aid for Scientific Research Grant-in-Aid for Encouragement of Young Scientists (A)
    1997 - 1998
    加藤 祐次
    近年、光による生体計測の研究が盛んに行なわれているが、生体組織は強い散乱性を有し光計測の発展に大きな妨げとなっている。そのため本研究では、従来の光のみによる計測に対して、音響光学効果を用いて媒質の局所的な特性を変化させることによる光生体計測の計測能力向上を目指し、より高機能な計測手法を開発することを最終目的とした。この目的のため、本研究期間において光散乱体における音響光学効果について2つの視点から検討を行った。得られた研究成果は、以下に示す通りである。
    1. 音響光学効果に伴う屈折率の変化による局所反射光検出
    媒質に超音波を照射すると媒質中の屈折率は正弦的に変化するため、局所的な屈折率変化による反射により局所的な光学特性の検出が可能である考えられる。そこで、超音波を照射した媒質に光を入射してOptical Coherence Tomography法を用いて局所的な反射光の検出について検討を行った。その結果、局所的な反射光は確認できなかった。しかしながら要因としてパワー及び周波数が小さいために屈折率変化やその勾配が小さいことか挙げられるため、今後それらの改善により検出の可能性はまだあるものと考えられる。
    2. 音響光学効果による後方散乱光の時間分解波形への影響
    光散乱媒質に短パルス光を入射し、その後方散乱光の時間分解波形をストリークカメラを用いて、音響光学効果の後方散乱光への影響について評価を行った。その結果、音響光学効果により後方散乱光の時間分解波形に局所的な変化が現れることが明らかとなった。また、それは超音波の位相に応じて変化の様子も異なることが明らかとなった。
    以上の結果より、光生体計測に領域において利用価値の高い後方散乱光の時間分解波形に、局所的に能動的な変化を与えることが可能となった。そのため、従来の光のみの計測に対し、本手法はより空間的に高分解能計測の可能性を有することが明らかとなった。
    Japan Society for the Promotion of Science, Grant-in-Aid for Encouragement of Young Scientists (A), Hokkaido University, Principal investigator, Competitive research funding, 09750042
  • 生体透過snake photon検出のための基礎研究
    Grants-in-Aid for Scientific Research Grant-in-Aid for Exploratory Research
    1997 - 1998
    清水 孝一, 北間 正崇, 加藤 祐次
    未だ未知の点の多いsnake photonに対し、その基礎的な特性を明らかにすること、またその生体透視への応用ひいては光CT実現へ向けたbreakthroughの可能性を拓くことをめざし、次の研究を行った。
    1.高濃度散乱体におけるsnake photonの理論的解析
    モンテカルロシミュレーションにより、snake photonのふるまいを調べた。
    2.生体に近い散乱体溶液を用いたsnake photonの実験的解析
    試料には、散乱吸収特性が既知で、生体組織の光学パラメータとの関係が明らかなIntralipid水溶液を用いた。高出力レーザ、高感度受光器、分光系を中心とする実験システムを設計・製作し、snake photonの特性を実験的に解析した。
    これらの結果、次の成果が得られた。
    1.生体組織のような高濃度散乱体を透過した光の中にsnake photonが、既存技術で十分検出可能なレベル含まれることが明らかとなった。
    2.snake photonの時間分割解析を行ったところ、一般的なtime-gating法による散乱抑制で用いられる時間範囲を超えた部分にも、無視できぬ量のsnake photonが存在していることが見出された。
    これらの結果は、snake photonを有効に分離抽出することができれば、生体の光透視イメージングにおける新たな散乱抑制法が得られる可能性を示唆するものと考えられる。
    Japan Society for the Promotion of Science, Grant-in-Aid for Exploratory Research, Hokkaido University, Coinvestigator not use grants, Competitive research funding, 09878205
  • Development of CT Imaging Technique Using Multi-wavelengh and Ultra-short Light Pulse
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    1996 - 1997
    SHIMIZU Koichi, FUKUSHIMA Kikuro, KUDO Nobuki, KAYTO Yuji, YAMAMOTO Katsuyuki
    A fundamental study was conduced to realize the transilumination and the CT imaging of biological functions using multi-wavelength and ultra-short light pulse. Through this research the following progresses were made.
    (1) Through theoretical and experimental study, it was shown that we can get the image of functional change occurred inside an animal body using the light of multiple wavelengths in near-infrared region. The imaging can be perfomed noninvasively with a relatively simple apparatus.
    (2) A transilumination imaging system was developed based on the proposed principle. Using this system, the imaging of brain functions was attempted using small experimental animals. As a result, we could succeeded in imaging the transmission change localized in the rat brain when a somatosensory stimulation was applied. It was confirmed that the change appeared in symmetrical positions of left and right cerebral hemispheres at the contra-lateral side of the stimulated limbs. This result seems to be the first case which verified the feasibility of transilumination imaging of the cerebral functions.
    (3) An optical CT system was developed, and the functional imaging in the crosssectional image was attempted. Using this system, we could detect the oxygenation change of the kidney in the CT image of the mouse abdomen.
    (4) An experimental system of an ultra-short light pulse was constructed with a femto-second laser and a streak camera. This enabled us to analyze a time-resolved light pulse from a svattering medium.
    (5) A reconstruction technique was newly developed to obtain crosssectional image of highly scattering medium using backscattered light. In computer simulations and phantom experiments, the effectiveness of this technique was confirmed.
    (6) The scattered component in transmitted light was investigated in the time-resolved analysis of an ultra-short light pulse. The behavior and prepertes of a snake photon or near-axis scattered light which propagates along the optical axis of the incident beam of light were clarified. Based on this result, the possibility was found to suppress the scattering effect much more effective than the conventional time-gating method.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, Coinvestigator not use grants, Competitive research funding, 08458281
  • Development of Multi-channel Biotelemetry System for Advanced Emergency Medicine
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    1996 - 1997
    SHIMIZU Koichi, MIKAMI Tomohisa, YAMASHITA Masaji, HATSUDA Takeshi, KATO Yuji
    For advanced emergency medicine, a multi-channel data transmission system was developed. This system can send the color image, audio signal and biosignals of a patient such as electrocardiograms and blood pressures form moving ambulance to an emergency room of a hospital. With this system, the medical doctor in a hospital can understand the condition of the patient in an ambulance and can give instructions of treatment to a paramedic staff in the ambulance. They can start the advanced treatments in the ambulance which have been legally prohibited without the instruction of a licensed medical doctor. The process and the results of this resarch are as follows.
    (1) The technical difficulties and problems were identified to transmit many kinds of information through a common narrow-band communication network which has been designed mainly for vocal communications. The techniques to overcome these problems were developed.
    (2) An experimental system was developed. It consists of a mobile station to be mounted in an ambulance and a fixed station in an emergency room in a hospital. They were connected by a mobile communication network.
    (3) The mobile station was equipped in a car and transmission experiment was conducted from a moving car. There was no problem found in the transmission from the moving car in a regular running condition.
    (4) To examine the effects of terrain, high buildings and bad weather, the transmission experiments were repeated in conceivable adverse conditions. The quality of transmitted data was deteriorated to some extent. However, it was confirmed that the signal quality was still satisfactory for practical use in emergency medicine.
    (5) The feasibility was investigated to extend this technique to cover much wider global area using movile satellite communication. It was shown that the wide-area emergency care was feasible by solving the problem of transmission delay due to satellite communication link. Through the experiment using the satellite communication, this feasibility was verified.
    (6) The developed system was equipped on an operating ambulance of Sapporo Fire Department, and the practical usefulness of this technique was examined. As a result, the satisfactory evaluation was given by a medical doctor specialized in an emergency medicine.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, Coinvestigator not use grants, Competitive research funding, 08555088
  • Optical delivery system for painless laser dentistry
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    1995 - 1997
    MIYAGI Mitsunobu, HONGO Akihito, KATO Yuji, HARA Hiroaki, MATSUURA Yuji
    The purpose of this research is development of optical delivery systems for dentistry which enables painless dental treatment. The system utilizes Er : YAG laser as the light source and hollow waveguides as the beam delivery medium. In this research, in addition to flexible waveguides, fixedbent waveguides, visible light delivery systems, and beam launching couplers are studied for development of total laser systems. The hollow waveguides that is the basis of this research deliver high-powered, infrared laser light and the waveguides are robust and stable for long term.
    The following is the main result of this research :
    1.Loss reduction of hollow glass waveguides for Er : YAG laser light
    Hollow glass waveguides are fabricated by a liquid-phase deposition technique using mirror plating method and polymer liquid coating method. The waveguides consist of a silica capillary tube, a silver layr on the inside of the tube, and a polyimide thin film on the further inside of the silver layr. The waveguides withstand more tna 100mJ of input energy and also has a low transmission loss less than 0.3dB/m.
    2.Development of additional devices fro hollow wveguides
    A lensed-taper, launching coupler for hollow waveguides is newly proposed and developed. The coupler enhance the coupling between the input laser beam and the hollow waveguides. In addition, a beam homogenizer for hollow waveguides is develped by utilizing a silver-halide, infrared fiber.
    3.Biological test of the beam delivery system for Er : YAG laser
    Under the corroboration with a manufacturer of dental systems, biological tests using a polyimidecoated, hollow glass waveguide were performed and obtained a good result of painless treatment.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Tohoku University, Coinvestigator not use grants, Competitive research funding, 07558120
  • 人工電磁環境の人体影響の定量的解析と安全性評価
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Priority Areas
    1996 - 1996
    清水 孝一, 清水 久恵, 福島 菊郎, 加藤 祐次
    近年,高圧送電線・各種の高出力電気機器など強力な電磁源が日常空間に現れ,我々は人類史上未経験の人工電磁環境にさらされている.各国でそれぞれ個別の安全基準が暫定的に設けられてはいるが,国によりその値が大きく異なっているのが現状である.その原因としては,生物学的および工学的根拠に基づく客観的評価法の欠如によるところが大きい.
    我々はこれまでの研究をとおし,人体のような複雑な構造に対する電磁界ならびに空間イオン流の曝露量の解析・評価法を確立してきた.またこれまでの動物実験の結果をもとに,電界感知閾値を指標としてヒトにおける影響を定量評価することを考えた.今年度はこれをさらに進め,交直両電界の生体影響の違いについて詳しい解析を行うとともに,電界感知に伴う生理的変化について調べた.
    まず,人工電磁環境の生体影響の定量解析をめざし,独自に開発した体表刺激反応計測法を用いてヒトに対する電界曝露実験を行った.その結果電界の生体作用の変化を,感知閾値の変化として定量化することができた.またこの定量解析をとおし,電界感知の主因である体表刺激作用が主として体毛の動きによって生ずること,その刺激作用が交流と直流で異なること,またその違いは相対湿度による閾値変化に比べると小さいことなどが明らかとなった.さらに曝露実験をとおし,感知閾値レベルの電界による体表刺激でも,人体に生理的変化をもたらす可能性を示唆する結果を得た.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Priority Areas, Hokkaido University, Coinvestigator not use grants, Competitive research funding, 08255204
  • Highly Intelligent Delivery System in Biomedical Optics
    Grants-in-Aid for Scientific Research Grant-in-Aid for international Scientific Research
    1995 - 1996
    MIYAGI Mitsunobu, SU D, CROITORU N, HARA Hiroaki, MATSUURA Yuji, BABA Kazutaka, BAKER H.J, HALL D.R, HARRINGTON J.A, KATZIR A
    There has been increasing interest in minimal invasive medicine that is a new type of treatment and diagnosis technique making no large damage or pain to human body. Biomedical optics is a main research area of the minimal invasive medicine and various lasers have been developed for medical applications. For high performance of the medical laser system, an efficient beam delivery equipment is necessary.
    A purpose of this project is to develop a highly efficient, laser delivery system equipped with a hollow waveguide as a flexible delivery medium. Main results achieved this term are as follows :
    1) Held international conferences on biomedical optics
    BiOS Europe '96 : September '96 (Vienna, Austria)
    BiOS '97 : February '97 (San Jose, USA)
    GCL/HPL '96 : August '96 (Edinburgh, UK)
    2) Development of extremely-low-loss hollow fiber and efficient fabrication process Hollow waveguides with multiple dielectric layrs were fabricated to obtain an extremely low-loss hollow fibers. Basic experiments to choose an appropriate dielectric material was performed and the result showed that polymers, such as polyimide and fluorocarbon, and inorganic materials, for example, zinc sulfide, germanium, silver iodide, were chosen as suitable materials for low-loss hollow fibers.
    As for development of highly efficient fabrication process, we developed an all liquid-phase deposition method. In this method, coating of dielectric as well as metal layr is performed by using a liquid-flow-and-dry method. For this method, we also found that polymer films are appropriate dielectric material.
    3) Development of optical attachment for hollow waveguides
    Optical attachments for a high-performance, laser delivery system were developed. For input end of hollow waveguides, we proposed a lensed-taper launching coupler for high efficient coupling between incident laser beam and hollow waveguides. This coupler also prevent a guide's end from a damage due to miscoupling. For output end, we developed a fixed-bent, hollow fiber piece and a beam homogenizer for easy handling of total delivery system.
    Japan Society for the Promotion of Science, Grant-in-Aid for international Scientific Research, Tohoku University, Coinvestigator not use grants, Competitive research funding, 07044113
  • STUDIES ON LASER TRANSMISSION DEVICES FOR MINIMALLY INVASIVE MEDICINE
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    1994 - 1996
    MIYAGI Mitsunobu, KATO Yuji, HORIGUCHI Tsuyoshi, ONODERA Shinji, MATSUURA Yuji
    We have investigated transmission devices of infrared laser light for minimally invasive medicine. The results obtained under the project are summarized as follows :
    1.Development of zinc sulfide-coated silver hollow nickel waveguide
    Based on sputtering, electroplating, and etching techniques, we have successfully fabricated zinc sulfide-coated silver hollow nickel waveguides with small losses. THe waveguides are durable and can transmit Er : YAG laser light with the energy of 1.6 J,which suggests the necessity of developing an efficient fabrication method of dielectric-coated hollow waveguides.
    2.Fabrication method of polymer-coated silver hollow waveguides
    In order to fabricate long hollow waveguides efficiently, a new fabrication method based on all liquid phase method has been developed and polyimide or fluorocarbon polymer-coated silver hollow glass waveguides have been obtained for practical dental applications.
    3.Proposal of "Total Delivery System" and design of optical elements
    A new idea of total delivery system has been introduced which uses hollow waveguides and several optical devices such as input launching coupler and and output optical elements are fabricated. The input launching coupler is consisting of a lens and tapered hollow waveguides which has large tolerance in optical misalignment of input beam.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), TOHOKU UNIVERSITY, Competitive research funding, 06402041
  • 光薄膜の多重共鳴吸収を用いた超細径中空ファイバー型光センサーの研究
    Grants-in-Aid for Scientific Research Grant-in-Aid for Encouragement of Young Scientists (A)
    1995 - 1995
    加藤 祐次
    光薄膜の多重共鳴吸収を用いた超細径中空ファイバー型光センサーの開発を目的として、中空導波路の製造プロセスの改善、更に理論的な検討によるセンシングデバイスとしての有効性を検討した。結果は以下のようにまとめられる。
    1.超細径伝送路の製作技術の確立
    赤外領域で重要とされるEr:YAG、CO_2レーザ光用の高性能な伝送路の実現のため、内径540〜700μm、長さ1m程度のポリイミド及びフッ素樹脂内装銀中空導波路の製作手法を確立することを目的として、製作条件の改善を中心に検討を行った。基本的には、母材パイプに内面精度が高くフレキシブルな石英キャピラリーチューブを用いて、内面に銀及び高分子層を成膜する工程である。このプロセスの中で、銀層成膜時における銀鏡反応条件およびポリイミド層成膜時における乾燥条件について詳細な検討およびプロセス改善を行った結果、光学特性の観点から導波路の安定した製作が可能となり、またプロセスの改善に伴う低損失化も図ることができた。更に、従来まで2μ以上の中赤外領域での特性評価に加え、可視・近赤外領域における特性評価を行った結果、製作した導波路の内装高分子層の膜厚の均一性が従来のものに比べて非常に向上したことが明らかとなった。
    2.中空導波路のセンシングデバイスへの応用のための基礎検討
    高分子層内装中空導波路をセンシングデバイスの性能について理論的に基礎検討を行った。測定原理はセンシング媒体と高分子層との相互作用による光の干渉効果の変化であり、この原理では光の絶対量に変化に依存せず安定な手法である。検討事項については、液体の屈折率の濃度依存性や環境温度に対する高分子層の屈折率及び膜厚の変化に依存する光の干渉ピークのシフト量との関係を中心に調査した結果、センシングデバイスの基礎特性として液体の屈折率に対して比較的精度の良いセンシングの可能性が見いだされた。
    Japan Society for the Promotion of Science, Grant-in-Aid for Encouragement of Young Scientists (A), Hokkaido University, Principal investigator, Competitive research funding, 07750379
  • Development of ultra-low loss glass hollow waveguides transmitting infrared light with several wavelengths simultaneously
    Grants-in-Aid for Scientific Research Grant-in-Aid for Developmental Scientific Research (B)
    1992 - 1994
    MIYAGI Mitsunobu, HONGO Akihito, ONODERA Shinji, KATO Yuji
    In this research project, we tried to realize infrared glass hollow waveguides with ultra-low losses which can transmit the laser light such as Er : YAG,CO,and CO_2 laser light with several wavelengths simultaneously or independently for medical applications. The main results obtained during the research period are as follows :
    1.Fabrication of ZnS-coated Ag hollow waveguides by outer deposition technique In order to fabricate dielectric-coated waveguides with a completely circular cross section along the propagation axis, we employed a new mandrel for the outer deposition method. By using a polyimide-coated glass pipe as a mandrel, ZuS-coated Ag hollow waveguides have been fabricated and the maximum energy of 1.6 J of Er : YAG laser light has been successfully transmitted without siginificant degradation of waveguides. This shows that ZuS-coated Ag waveguide can be used for high-energy transmission media and for dental application.
    2.Fabrication of polymer-coated Ag hollow glass waveguides by liquid phase method After depositing a this silver layr inside a fused silica tube with an ultra-smooth inner surface by using a silver mirror reaction method, polyimide or fluorocarbon polymer has been deposited by using a liquid flow coating method or dipping method. Thin hollow waveguides with inner diameters of 700 mum and 540 mum have been fabricated for transmitting Er : YAG laser light with small losses.
    3.Studies on mode structures of hollow waveguides Based on the exact characteristic equation, mode structures and mode transitions of circular hollow waveguides with and without inner dielectric layr have been fully clarified. Properties of lower order modes in a uniformly bent circular hollow waveguide are also made clear.
    Japan Society for the Promotion of Science, Grant-in-Aid for Developmental Scientific Research (B), TOHOKU UNIVERSITY, Coinvestigator not use grants, Competitive research funding, 04555082

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