Prof. Keiichiro Kagawa Profile

Prof. Keiichiro Kagawa

Professor at Shizuoka Univ

SPIE Involvement:

Author

Publications (63)

Proceedings Article | 13 March 2024 Presentation + Paper

Simultaneous imaging of shallow and deep tissues based on multi-line scanning

Naoshi Yoneyama, Sota Nakazawa, Kanta Iyanagi, Yusuke Tanihata, Ryotaro Mori, Manabu Machida, Gordon Kennedy, Anthony Durkin, Keiichiro Kagawa

Proceedings Volume 12816, 1281608 (2024) https://doi.org/10.1117/12.3000865

KEYWORDS: Tissues, Near infrared spectroscopy, Tissue optics, Absorption, Monte Carlo methods, Silicon, Reflectivity, Diffuse reflectance spectroscopy, Scattering, Optical testing

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Proceedings Article | 13 March 2024 Presentation + Paper

High-sensitivity 648x484-pixel CMOS image sensor for wide-field FLIM with four simultaneous time gates

Ibuki Ando, Kamel Mars, Keita Yasutomi, Shoji Kawahito, Keiichiro Kagawa

Proceedings Volume 12836, 1283605 (2024) https://doi.org/10.1117/12.3002329

KEYWORDS: Fluorescence lifetime imaging, Fluorescence, CMOS sensors, Image sensors, LIDAR, Copper indium disulfide, Modulators, Quantum gates, Spatial resolution, Quantum measurement

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SPIE Journal Paper | 18 January 2024 Open Access

Motion-resistant three-wavelength spatial frequency domain imaging system with ambient light suppression using an 8-tap CMOS image sensor

Yu Feng, Chen Cao, Yuto Shimada, Keita Yasutomi, Shoji Kawahito, Gordon Kennedy, Anthony Durkin, Keiichiro Kagawa

JBO, Vol. 29, Issue 01, 016006, (January 2024) https://doi.org/10.1117/12.10.1117/1.JBO.29.1.016006

KEYWORDS: Image sensors, Imaging systems, Reflectivity, Tissues, Video, Biomedical optics, Image processing, Skin, In vivo imaging, Optical properties

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SignificanceWe present a motion-resistant three-wavelength spatial frequency domain imaging (SFDI) system with ambient light suppression using an 8-tap complementary metal-oxide semiconductor (CMOS) image sensor (CIS) developed at Shizuoka University. The system addresses limitations in conventional SFDI systems, enabling reliable measurements in challenging imaging scenarios that are closer to real-world conditions.AimOur study demonstrates a three-wavelength SFDI system based on an 8-tap CIS. We demonstrate and evaluate the system’s capability of mitigating motion artifacts and ambient light bias through tissue phantom reflectance experiments and in vivo volar forearm experiments.ApproachWe incorporated the Hilbert transform to reduce the required number of projected patterns per wavelength from three to two per spatial frequency. The 8-tap image sensor has eight charge storage diodes per pixel; therefore, simultaneous image acquisition of eight images based on multi-exposure is possible. Taking advantage of this feature, the sensor simultaneously acquires images for planar illumination, sinusoidal pattern projection at three wavelengths, and ambient light. The ambient light bias is eliminated by subtracting the ambient light image from the others. Motion artifacts are suppressed by reducing the exposure and projection time for each pattern while maintaining sufficient signal levels by repeating the exposure. The system is compared to a conventional SFDI system in tissue phantom experiments and then in vivo measurements of human volar forearms.ResultsThe 8-tap image sensor-based SFDI system achieved an acquisition rate of 9.4 frame sets per second, with three repeated exposures during each accumulation period. The diffuse reflectance maps of three different tissue phantoms using the conventional SFDI system and the 8-tap image sensor-based SFDI system showed good agreement except for high scattering phantoms. For the in vivo volar forearm measurements, our system successfully measured total hemoglobin concentration, tissue oxygen saturation, and reduced scattering coefficient maps of the subject during motion (16.5 cm/s) and under ambient light (28.9 lx), exhibiting fewer motion artifacts compared with the conventional SFDI.ConclusionsWe demonstrated the potential for motion-resistant three-wavelength SFDI system with ambient light suppression using an 8-tap CIS.

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Proceedings Article | 17 March 2023 Presentation

Model for skin response due to noxious heating using a spatial frequency domain imaging system with compact eye camera

Nandan Das, Saad Nagi, Keiichiro Kagawa, Rolf Saager

Proceedings Volume PC12352, PC123520O (2023) https://doi.org/10.1117/12.2649804

KEYWORDS: Imaging systems, Tissues, Cameras, Skin, Scattering, Eye models, Eye, Near infrared, Inflammation, Absorption

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Proceedings Article | 7 March 2023 Presentation + Paper

Demonstration of motion-resistant three-wavelength spatial frequency domain imaging system with ambient light suppression using an 8-tap CMOS image sensor

Yu Feng, Yuto Shimada, Chen Cao, Keita Yasutomi, Shoji Kawahito, Gordon Kennedy, Anthony Durkin, Keiichiro Kagawa

Proceedings Volume 12376, 123760D (2023) https://doi.org/10.1117/12.2649418

KEYWORDS: Image sensors, CMOS sensors, Tissues, Reflectivity, Imaging systems, Light scattering, Scattering, Cameras, Biological imaging, Sensors

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Proceedings Article | 2 March 2022 Presentation + Paper

A 2x2-aperture 4-tap multi-modal tissue imager for multi-band SFDI and MELSCI

Yuto Shimada, Kazuki Takada, Hoang Son Nam, Kakeru Miyazaki, Keita Yasutomi, Shoji Kawahito, Christian Crouzet, Bernard Choi, Gordon Kennedy, Anthony Durkin, Keiichiro Kagawa

Proceedings Volume 11951, 1195107 (2022) https://doi.org/10.1117/12.2608397

KEYWORDS: Tissues, Imaging systems, CMOS sensors, Image sensors, Scattering, Tissue optics

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Proceedings Article | 2 March 2022 Presentation + Paper

Demonstration of 3-band spatial frequency domain imaging using an 8-tap CMOS image sensor resistant to subject motion and ambient light

Kazuki Takada, Yuto Shimada, Keita Yasutomi, Shoji Kawahito, Gordon Kennedy, Anthony Durkin, Keiichiro Kagawa

Proceedings Volume 11951, 1195106 (2022) https://doi.org/10.1117/12.2608412

KEYWORDS: CMOS sensors, Scattering, Sensors, Absorption, Tissues, Reflectivity, Oxygen, Image sensors, Imaging systems, Spatial frequencies

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Proceedings Article | 27 October 2021 Paper

Finger region extraction using color of skin for hand-waving finger vein authentication

Hiroyuki Suzuki, Narissa Ditthapakdijanya, Takashi Komuro, Keiichiro Kagawa, Kazuya Nakano, Takashi Obi

Proceedings Volume 11925, 119250X (2021) https://doi.org/10.1117/12.2615690

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Proceedings Article | 27 October 2021 Paper

Integrated optical imaging system composed of optical time-of-flight and optical coherence tomography

Juan Manuel Franco Sanchez, Yuki Shimamoto, Shunya Masaki, Joel Cervantes, Quang Duc Pham, Keiichiro Kagawa, Hajime Nagahara, Yoshio Hayasaki

Proceedings Volume 11925, 119250T (2021) https://doi.org/10.1117/12.2615676

KEYWORDS: Optical coherence tomography, Integrated optics, Imaging systems, System integration, Modulation, Mirrors, Light sources, Spectroscopy, Optical imaging, Target detection

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Proceedings Article | 9 October 2021 Presentation + Paper

Optical time of flight and an autofocus system using a variable focal length lens

Juan M. F. Sanchez, Joel C. Lozano, Keiichiro Kagawa, Hajime Nagahara, Yoshio Hayasaki

Proceedings Volume 11895, 118950P (2021) https://doi.org/10.1117/12.2602552

KEYWORDS: Photodetectors, Fourier transforms, Modulation, LabVIEW, Distance measurement, Beam splitters, Signal processing, Signal detection, Light, Control systems

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SPIE Journal Paper | 12 August 2021 Open Access

Spatial frequency domain imager based on a compact multiaperture camera: testing and feasibility for noninvasive burn severity assessment

Gordon Kennedy, Keiichiro Kagawa, Rebecca Rowland, Adrien Ponticorvo, Jun Tanida, Anthony J Durkin

JBO, Vol. 26, Issue 08, 086001, (August 2021) https://doi.org/10.1117/12.10.1117/1.JBO.26.8.086001

KEYWORDS: Imaging systems, Cameras, Optical properties, Tissue optics, Scattering, Skin, Tissues, Optical testing, Remote sensing, Injuries

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Significance: Spatial frequency domain imaging (SFDI) is a wide-field imaging technique that provides quantitative maps of tissue optical properties. We describe a compact SFDI imager that employs a multispectral compound-eye camera. This design enables simultaneous image acquisition at multiple wavelengths. Such a device has potential for application for quantitative evaluation of superficial tissues by nonspecialists in low-resource settings. Aim: The aim of this work was to develop a compact SFDI imager for widefield imaging of in-vivo tissue optical properties and verify its ability to measure optical properties of tissue-simulating phantoms and in a preclinical model of burn wounds. Approach: This compound-eye imager was constructed using a CMOS sensor subdivided into multiple regions, each having a bandpass filter and objective lens. The ability of the instrument to image optical properties was compared with (1) a commercial SFDI imager and (2) a laboratory-based system. Initial validation of ability to accurately characterize optical properties was performed using a tissue-simulating optical phantom. It was then applied to an established murine model of thermal contact burn severity. In-vivo measurements of the optical properties of rat skin were performed before and after the application of burns. Histology was used to verify burn severity. Results: Measurements of the tissue-simulating phantom optical properties made using the compound-eye imager agree with measurements made using the two comparison SFDI devices. For the murine burn model, the burns showed a decrease in the reduced scattering coefficient at all measurement wavelengths compared with preburn measurements at the same locations. This is consistent with previously reported changes in scattering that occur in full-thickness burns. Conclusion: We demonstrate the potential for SFDI to be translated into compact form factor using a compound-eye camera that is capable of obtaining multiple wavelengths channels simultaneously.

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Proceedings Article | 30 March 2021 Presentation

A multi-aperture multi-tap image sensor for simultaneous multi-band SFDI and multi-exposure laser speckle contrast blood flow imaging

Keiichiro Kagawa, Gordon Kennedy, Adrien Ponticorvo, Iori Shibata, Keita Yasutomi, Shoji Kawahito, Jun Tanida, Christian Crouzet, Bernard Choi, Anthony Durkin

Proceedings Volume 11651, 116510H (2021) https://doi.org/10.1117/12.2578055

KEYWORDS: Image sensors, Blood circulation, Speckle, Modulators, Laser speckle contrast imaging, Imaging devices, Cameras, Video, Tissue optics, Spatial frequencies

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Proceedings Article | 9 March 2021 Presentation + Paper

Spatio-temporal frequency domain imaging using time-resolving CMOS image sensor and stripe pattern projection

K. Takada, K, Osada, M. Machida, Y. Hoshi, K. Yasutomi, S. Kawahito, K. Kagawa

Proceedings Volume 11639, 116391C (2021) https://doi.org/10.1117/12.2577981

KEYWORDS: CMOS sensors, Tissues, Near infrared spectroscopy, Monte Carlo methods, Brain, Skull, Skin, Scattering, Modulators, Light scattering

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Proceedings Article | 5 March 2021 Presentation

Portable visible and near-infrared spatial frequency domain imaging system to measure skin reactivity in response to noxious heating using a multi-spectral compound eye camera

Nandan Kumar Das, Saad Nagi, Keiichiro Kagawa, Jun Tanida, Rolf Saager

Proceedings Volume 11633, 116330G (2021) https://doi.org/10.1117/12.2577178

KEYWORDS: Skin, Imaging systems, Cameras, Eye, Visible radiation, Tissue optics, Water, Tissues, Spectral resolution, Signal to noise ratio

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Proceedings Article | 5 March 2021 Presentation + Paper

A compact spatial frequency domain burn imager employing a compound–eye camera

Gordon Kennedy, Keiichiro Kagawa, Adrien Ponticorvo, Rebecca Rowland, Jun Tanida, Anthony Durkin

Proceedings Volume 11618, 116180H (2021) https://doi.org/10.1117/12.2579125

KEYWORDS: Imaging systems, Cameras, Scattering, Tunable filters, Tissues, Tissue optics, Spatial frequencies, Sensors, Optical properties

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Proceedings Article | 10 October 2020 Poster + Presentation + Paper

Integration of time-of-flight distance measurement and optical coherence tomography for extending its operating range

Juan Manuel Franco Sánchez, Shunya Masaki, Yuki Shimamoto, Joel Cervantes, Keiichiro Kagawa, Hajime Nagahara, Yoshio Hayasaki

Proceedings Volume 11549, 115491M (2020) https://doi.org/10.1117/12.2575254

KEYWORDS: Optical coherence tomography, Distance measurement, Medical imaging, Image resolution, Superluminescent diodes, Optical fibers, Spectroscopy, Semiconductor lasers, Modulation, Ranging

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Proceedings Article | 11 March 2020 Paper

Development of a mobile TOMBO system for multi-spectral imaging

Tetsuya Nakanishi, Keiichiro Kagawa, Yasuo Masaki, Jun Tanida

Proceedings Volume 11331, 1133102 (2020) https://doi.org/10.1117/12.2553008

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Proceedings Article | 21 February 2020 Paper

A time-resolved near-infrared spectroscopy based on CMOS image sensor

De Xing Lioe, Masashi Hakamata, Keita Yasutomi, Keiichiro Kagawa, Masatsugu Niwayama, Yasuko Fukushi, Seiji Yamamoto, Shoji Kawahito

Proceedings Volume 11234, 112340P (2020) https://doi.org/10.1117/12.2545581

KEYWORDS: Near infrared spectroscopy, CMOS sensors, Absorption, Sensors, Scattering, Laser scattering, Reflectivity, Image sensors, Light sources, Light scattering

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Proceedings Article | 17 February 2020 Presentation + Paper

A multiplexed confocal FLIM microscope with 4-taps time-gated imager

Morgan Richards, Yuya Shirakawa, Fares Badr, Keiichiro Kagawa, Shoji Kawahito, Qiyin Fang

Proceedings Volume 11245, 1124512 (2020) https://doi.org/10.1117/12.2550208

KEYWORDS: Confocal microscopy, Imaging systems, Fluorescence lifetime imaging, Microscopes, Sensors, Multiplexing, Luminescence, Relays, Microlens array, Biomedical optics

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Proceedings Article | 21 February 2019 Paper

A real-time driver monitoring system using a high sensitivity camera

Leyi Tan, Masashi Hakamata, Chen Cao, Keiichiro Kagawa, Norimichi Tsumura, Shoji Kawahito

Proceedings Volume 10883, 108831G (2019) https://doi.org/10.1117/12.2507181

KEYWORDS: Heart, Video, Cameras, Signal detection, Imaging systems, Independent component analysis, Electronic filtering, Nervous system, Skin, RGB color model

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Proceedings Article | 1 August 2018 Presentation + Paper

Kyoto's event-driven x-ray astronomy SOI pixel sensor for the FORCE mission

Takeshi Tsuru, Hideki Hayashi, Katsuhiro Tachibana, Soudai Harada, Hiroyuki Uchida, Takaaki Tanaka, Yasuo Arai, Ikuo Kurachi, Koji Mori, Ayaki Takeda, Yusuke Nishioka, Nobuaki Takebayashi, Shoma Yokoyama, Kohei Fukuda, Takayoshi Kohmura, Kouichi Hagino, Kenji Ohno, Kohsuke Negishi, Keigo Yarita, Shoji Kawahito, Keiichiro Kagawa, Keita Yasutomi, Sumeet Shrestha, Shunta Nakanishi, Hiroki Kamehama, Hideaki Matsumura

Proceedings Volume 10709, 107090H (2018) https://doi.org/10.1117/12.2312098

KEYWORDS: Sensors, X-rays, Silicon, X-ray astronomy, CMOS sensors, X-ray imaging, X-ray detectors, Imaging devices

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Proceedings Article | 1 May 2017 Presentation + Paper

A stick-shaped multi-aperture camera for intra-oral diagnosis

Jun Tanida, Hirotsugu Akiyama, Keiichiro Kagawa, Chizuko Ogata, Makoto Umeda

Proceedings Volume 10222, 102220L (2017) https://doi.org/10.1117/12.2265507

KEYWORDS: 3D metrology, Teeth, RGB color model, Reflectivity, Projection systems, 3D image processing, Imaging systems, Computational imaging, Cameras, Image sensors, Visible radiation, Optical design, Microlens, Medical diagnostic instruments, Spectral data processing

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Proceedings Article | 22 February 2017 Paper

A high performance multi-tap CMOS lock-in pixel image sensor for biomedical applications

Min-Woong Seo, Yuya Shirakawa, Keiichiro Kagawa, Keita Yasutomi, Shoji Kawahito

Proceedings Volume 10076, 100760V (2017) https://doi.org/10.1117/12.2255951

KEYWORDS: Sensors, CMOS sensors, Fluorescence lifetime imaging, Biomedical optics, Microscopy, Signal detection, Image sensors, Modulation, Imaging systems, Signal to noise ratio, Modulators, Prototyping, Photodiodes, Analog electronics

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Proceedings Article | 20 February 2017 Paper

Design of an 8-tap CMOS lock-in pixel with lateral electric field charge modulator for highly time-resolved imaging

Yuya Shirakawa, Min-Woong Seo, Keita Yasutomi, Keiichiro Kagawa, Nobukazu Teranishi, Shoji Kawahito

Proceedings Volume 10108, 101080N (2017) https://doi.org/10.1117/12.2251788

KEYWORDS: Signal detection, Modulators, Real time imaging, Imaging devices, Fluorescence lifetime imaging, CMOS sensors, Microscopy, Life sciences, Luminescence, Computer aided design, Imaging systems, Image processing

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Proceedings Article | 20 February 2017 Paper

A time-of-flight range image sensor using high-speed 4-tap lock-in pixels

A. Komazawa, H. Trang, T. Takasawa, S. Aoyama, K. Yasutomi, K. Kagawa, S. Kawahito

Proceedings Volume 10328, 1032806 (2017) https://doi.org/10.1117/12.2270543

KEYWORDS: Time of flight range image sensors, Modulators, Imaging systems, Image resolution, Electrons, Demodulation, Image processing, Photodiodes, Sensors, Calibration

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Proceedings Article | 16 February 2017 Paper

Spectroscopic analysis of autofluorescence distribution in digestive organ for unstained metabolism-based tumor detection

Hidenobu Arimoto, Atsushi Iwata, Keiichiro Kagawa, Yoji Sanomura, Shigeto Yoshida, Shoji Kawahito, Shinji Tanaka

Proceedings Volume 10068, 100681L (2017) https://doi.org/10.1117/12.2250776

KEYWORDS: Spectroscopy, Confocal microscopy, Tumors, Collagen, Luminescence, Tissue optics, Optical filters, Image sensors, Tissues, Bandpass filters

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Proceedings Article | 5 May 2016 Paper

Development of low read noise high conversion gain CMOS image sensor for photon counting level imaging

Min-Woong Seo, Shoji Kawahito, Keiichiro Kagawa, Keita Yasutomi

Proceedings Volume 9858, 985809 (2016) https://doi.org/10.1117/12.2229025

KEYWORDS: CMOS sensors, Photon counting, Image sensors, Capacitance, Image processing, Imaging systems, Analog electronics, Sensors, Interference (communication), Electrons

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Proceedings Article | 7 March 2016 Presentation + Paper

A CMOS image sensor using high-speed lock-in pixels for stimulated Raman scattering

DeXing Lioe, Kamel Mars, Taishi Takasawa, Keita Yasutomi, Keiichiro Kagawa, Mamoru Hashimoto, Shoji Kawahito

Proceedings Volume 9720, 97200J (2016) https://doi.org/10.1117/12.2213906

KEYWORDS: CMOS sensors, Raman scattering, Modulation, Amplifiers, Raman spectroscopy, Imaging spectroscopy, Spectroscopy, Image sensors, Modulators, Photodiodes, Interference (communication), Signal detection, Laser sources, Capacitors

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Proceedings Article | 7 March 2016 Presentation + Paper

Multi-aperture ultra-high-speed imaging with lateral electric field charge modulators

K. Kagawa, F. Mochizuki, M.-W. Seo, K. Yasutomi, S. Kawahito

Proceedings Volume 9720, 972003 (2016) https://doi.org/10.1117/12.2214273

KEYWORDS: CMOS sensors, Camera shutters, Image sensors, Image compression, Cameras, Modulation, Modulators, Charge-coupled devices, Video, Image resolution

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Proceedings Article | 26 August 2015 Paper

A low-noise wide-dynamic-range event-driven detector using SOI pixel technology for high-energy particle imaging

Sumeet Shrestha, Hiroki Kamehama, Shoji Kawahito, Keita Yasutomi, Keiichiro Kagawa, Ayaki Takeda, Takeshi Go Tsuru, Yasuo Arai

Proceedings Volume 9593, 95930X (2015) https://doi.org/10.1117/12.2188019

KEYWORDS: Sensors, Signal detection, Particles, CMOS sensors, X-rays, X-ray detectors, Transistors, Capacitors, Silicon, Logic

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Proceedings Article | 13 March 2015 Paper

A high-sensitivity 2x2 multi-aperture color camera based on selective averaging

Bo Zhang, Keiichiro Kagawa, Taishi Takasawa, Min-Woong Seo, Keita Yasutomi, Shoji Kawahito

Proceedings Volume 9403, 94030C (2015) https://doi.org/10.1117/12.2082780

KEYWORDS: Cameras, Sensors, Image quality, Interference (communication), Imaging systems, CMOS sensors, Distortion, Prototyping, Image sensors, Signal to noise ratio

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Proceedings Article | 22 June 2014 Paper

Development and performance of Kyoto's x-ray astronomical SOI pixel (SOIPIX) sensor

Takeshi Tsuru, Hideaki Matsumura, Ayaki Takeda, Takaaki Tanaka, Shinya Nakashima, Yasuo Arai, Koji Mori, Ryota Takenaka, Yusuke Nishioka, Takayoshi Kohmura, Takaki Hatsui, Takashi Kameshima, Kyosuke Ozaki, Yoshiki Kohmura, Tatsuya Wagai, Dai Takei, Shoji Kawahito, Keiichiro Kagawa, Keita Yasutomi, Sumeet Shrestha, Hiroki Kamehama

Proceedings Volume 9144, 914412 (2014) https://doi.org/10.1117/12.2057158

KEYWORDS: X-rays, X-ray astronomy, Sensors, Charge-coupled devices, X-ray detectors, CMOS sensors, X-ray imaging, Analog electronics, X-ray technology, Satellites

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Proceedings Article | 4 March 2014 Paper

A high fill-factor low dark leakage CMOS image sensor with shared-pixel design

Min-Woong Seo, Keita Yasutomi, Keiichiro Kagawa, Shoji Kawahito

Proceedings Volume 9022, 90220M (2014) https://doi.org/10.1117/12.2040897

KEYWORDS: Transistors, CMOS sensors, Imaging systems, Photodiodes, Amplifiers, Quantum efficiency, Signal to noise ratio, Stereolithography, Analog electronics, CMOS technology

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Proceedings Article | 4 March 2014 Paper

10×10-pixel 606kS/s multi-point fluorescence correlation spectroscopy CMOS image sensor

Keiichiro Kagawa, Taishi Takasawa, Zhang Bo, Min-Woong Seo, Kaita Imai, Jotaro Yamamoto, Masataka Kinjo, Susumu Terakawa, Keita Yasutomi, Shoji Kawahito

Proceedings Volume 8947, 894713 (2014) https://doi.org/10.1117/12.2041131

KEYWORDS: CMOS sensors, Fluorescence correlation spectroscopy, Cadmium sulfide, Prototyping, Electrons, Photodiodes, Image sensors, Analog electronics, Diodes, CMOS technology

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Proceedings Article | 4 March 2014 Paper

A time-resolved image sensor for tubeless streak cameras

Keita Yasutomi, SangMan Han, Min-Woong Seo, Taishi Takasawa, Keiichiro Kagawa, Shoji Kawahito

Proceedings Volume 9022, 902202 (2014) https://doi.org/10.1117/12.2041150

KEYWORDS: Streak cameras, Imaging systems, CMOS sensors, Image sensors, Logic, Picosecond phenomena, Modulation, Pulse generators, Clocks, Sensors

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Proceedings Article | 4 March 2014 Paper

An indirect time-of-flight measurement technique for sub-mm range resolution using impulse photocurrent response

Takahiro Usui, Keita Yasutomi, Han San Man, Taishi Takasawa, Keiichiro Kagawa, Shoji Kawahito

Proceedings Volume 9022, 90220W (2014) https://doi.org/10.1117/12.2041160

KEYWORDS: Modulation, Light sources, Sensors, Distance measurement, Phase shift keying, Pulsed laser operation, Picosecond phenomena, Clocks, Imaging systems, Distortion

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Proceedings Article | 4 March 2014 Paper

A CMOS time-of-flight range image sensor using draining only modulation structure

Sangman Han, Keita Yasutomi, Keiichiro Kagawa, Shoji Kawahito

Proceedings Volume 9022, 90220P (2014) https://doi.org/10.1117/12.2041184

KEYWORDS: Modulation, Time of flight range image sensors, Imaging systems, Image processing, Photodiodes, CMOS sensors, Sensors, Electrons, Doping, Amplifiers

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This paper presents new structure and method of charge modulation for CMOS ToF range image sensors using pinned photodiodes. Proposed pixel structure, the draining only modulator (DOM), allows us to achieve high-speed charge transfer by generating lateral electric field from the pinned photo-diode (PPD) to the pinned storage-diode (PSD). Generated electrons by PPD are transferred to the PSD or drained off through the charge draining gate (TXD). This structure realizes trapping-less charge transfer from the PPD to PSD. To accelerate the speed of charge transfer, the generation of high lateral electric field is necessary. To generate the electric field, the width of the PPD is changed along the direction of the charge transfer. The PPD is formed by the p+ and n layer on the p-substrate. The PSD is created by doping another n type layer for higher impurity concentration than that of the n layer in the PPD. This creates the potential difference between the PPD and PSD. Another p layer underneath the n-layer of the PSD is created for preventing the injection of unwanted carrier from the substrate to the PSD. The range is calculated with signals in the three consecutive sub-frames; one for delay sensitive charge by setting the light pulse timing at the edge of TXD pulse, another for delay independent charge by setting the light pulse timing during the charge transfer, and the other for ambient light charge by setting the light pulse timing during the charge draining. To increase the photo sensitivity while realizing high-speed charge transfer, the pixel consists of 16 sub-pixels and a source follower amplifier. The outputs of 16 sub-pixels are connected to a charge sensing node which has MOS capacitor for increasing well capacity. The pixel array has 313(Row) x 240(Column) pixels and the pixel pitch is 22.4μm. A ToF range imager prototype using the DOM pixels is designed and implemented with 0.11um CMOS image sensor process. The accumulated signal intensity in the PSD as a function of the TXD gate voltage is measured. The ratio of the signal for the TXD off to the signal for the TXD on is 33:1. The response of the pixel output as a function of the light pulse delay has also been measured.

Proceedings Article | 4 March 2014 Paper

A stimulated Raman scattering imager using high-speed lateral electric field modulator and lock-in pixels amplifiers

Kamel Mars, Beak Guseul, Sang Man Han, Taishi Takasawa, Keita Yasutomi, Keiichiro Kagawa, Mamoru Hashimoto, Shoji Kawahito

Proceedings Volume 9022, 90220D (2014) https://doi.org/10.1117/12.2042471

KEYWORDS: Signal detection, Amplifiers, Modulators, Raman scattering, Modulation, Imaging systems, Clocks, Signal processing, Photodiodes, Device simulation

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Proceedings Article | 19 February 2013 Paper

A custom CMOS imager for multi-beam laser scanning microscopy and an improvement of scanning speed

Min-Woong Seo, Keiichiro Kagawa, Keita Yasutomi, Shoji Kawahito

Proceedings Volume 8659, 865905 (2013) https://doi.org/10.1117/12.2004965

KEYWORDS: Confocal microscopy, Imaging systems, Laser scanners, Microlens array, Modulation, Microscopy, Image resolution, Multiplexers, Cadmium sulfide, Photodiodes

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Proceedings Article | 15 February 2012 Paper

A CMOS imager using focal-plane pinhole effect for confocal multibeam scanning microscopy

Min-Woong Seo, An Wang, Zhuo Li, Keita Yasutomi, Keiichiro Kagawa, Shoji Kawahito

Proceedings Volume 8298, 829807 (2012) https://doi.org/10.1117/12.908285

KEYWORDS: Confocal microscopy, Imaging systems, Microscopy, Microscopes, Sensors, Photodiodes, CMOS sensors, CMOS technology, Standards development, Active sensors

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Proceedings Article | 3 February 2012 Paper

Deep-focus compound-eye camera with polarization filters for 3D endoscopes

Keiichiro Kagawa, Eiji Tanaka, Kenji Yamada, Shoji Kawahito, Jun Tanida

Proceedings Volume 8227, 822714 (2012) https://doi.org/10.1117/12.908415

KEYWORDS: Polarization, Cameras, Endoscopes, Optical filters, Imaging systems, Super resolution, Point spread functions, Tissues, Prototyping, Wavefronts

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Proceedings Article | 8 September 2010 Paper

High-speed multispectral three-dimensional imaging with a compound-eye camera TOMBO

Keiichiro Kagawa, Naoki Fukata, Jun Tanida

Proceedings Volume 7797, 77970N (2010) https://doi.org/10.1117/12.862083

KEYWORDS: Multispectral imaging, Cameras, Optical filters, 3D image processing, Camera shutters, CMOS sensors, Prototyping, Imaging systems, Lenses, Image filtering

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Proceedings Article | 1 September 2009 Paper

A compact shape-measurement module based on a thin compound-eye camera with multiwavelength diffractive pattern projection for intraoral diagnosis

K. Kagawa, H. Tanabe, C. Ogata, R. Horisaki, Y. Ogura, Y. Nakao, T. Toyoda, Y. Masaki, M. Ueda, J. Tanida

Proceedings Volume 7442, 74420U (2009) https://doi.org/10.1117/12.827250

KEYWORDS: Projection systems, Diffractive optical elements, Cameras, Prototyping, Teeth, Imaging systems, Spatial resolution, Image sensors, 3D modeling, Optical filters

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Proceedings Article | 21 August 2009 Paper

Free-space optical data transmission using wavelength-division-multiplexing with a dedicated CMOS image sensor for indoor optical wireless LAN

K. Kagawa, J. Tanida

Proceedings Volume 7464, 74640E (2009) https://doi.org/10.1117/12.826874

KEYWORDS: CMOS sensors, Free space optics, Local area networks, Wavelength division multiplexing, Image sensors, Analog electronics, Data transmission, Data acquisition, Multiplexers, Optical communications

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Proceedings Article | 3 September 2008 Paper

A compound-eye imaging system with irregular lens-array arrangement

Ryoichi Horisaki, Yoshizumi Nakao, Takashi Toyoda, Keiichiro Kagawa, Yasuo Masaki, Jun Tanida

Proceedings Volume 7072, 70720G (2008) https://doi.org/10.1117/12.796698

KEYWORDS: Imaging systems, Super resolution, Error analysis, Image processing, Image sensors, Modulation, 3D image processing, Image resolution, Microlens, Objectives

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Proceedings Article | 21 February 2007 Paper

Demonstration of a low-voltage three-transistor-per-pixel CMOS imager based on a pulse-width-modulation readout scheme employed with a one-transistor in-pixel comparator

S. Shishido, I. Nagahata, T. Sasaki, K. Kagawa, M. Nunoshita, J. Ohta

Proceedings Volume 6501, 65010N (2007) https://doi.org/10.1117/12.704095

KEYWORDS: Imaging systems, Transistors, Amplifiers, Sensors, Photodiodes, CMOS technology, CMOS sensors, Power supplies, Prototyping, Digital electronics

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Proceedings Article | 7 March 2006 Paper

Flexible and extensible retinal prosthesis based on multi-chip architecture

Akihiro Uehara, Yasuo Terasawa, Takashi Tokuda, Keiichiro Kagawa, Masahiro Nunoshita, Jun Ohta

Proceedings Volume 6138, 61380R (2006) https://doi.org/10.1117/12.646202

KEYWORDS: Electrodes, Analog electronics, Packaging, Epoxies, Circuit switching, Switches, CMOS technology, Iridium, Silicon, Digital electronics

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Proceedings Article | 6 February 2006 Paper

In vitro and in vivo on-chip biofluorescence imaging using a CMOS image sensor

David Ng, Masamichi Matsuo, Takashi Tokuda, Keiichiro Kagawa, Masahiro Nunoshita, Jun Ohta

Proceedings Volume 6068, 606801 (2006) https://doi.org/10.1117/12.642591

KEYWORDS: Brain, Neuroimaging, In vivo imaging, Image sensors, Luminescence, In vitro testing, CMOS sensors, Imaging devices, Sensors, Optical filters

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Proceedings Article | 6 February 2006 Paper

An optical and potential dual-image CMOS sensor for bioscientific applications

Takashi Tokuda, Akio Yamamoto, Keiichiro Kagawa, Masahiro Nunoshita, Jun Ohta

Proceedings Volume 6068, 606802 (2006) https://doi.org/10.1117/12.642559

KEYWORDS: Sensors, CMOS sensors, Electrodes, Image sensors, Optical sensing, Luminescence, Optical imaging, Imaging systems, Optical sensors, Transistors

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Proceedings Article | 6 February 2006 Paper

A pulse-frequency-modulation vision chip using a capacitive feedback reset with an in-pixel 1-bit image processor

Keiichiro Kagawa, Shinya Yamamoto, Tetsuo Furumiya, Takashi Tokuda, Masahiro Nunoshita, Jun Ohta

Proceedings Volume 6068, 60680C (2006) https://doi.org/10.1117/12.642707

KEYWORDS: Image processing, Power supplies, Transistors, Photodiodes, Edge detection, Clocks, Linear filtering, Positive feedback, Digital image processing, High dynamic range imaging

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Proceedings Article | 7 March 2005 Paper

A CMOS image sensor with high-speed readout of multiple regions-of-interest for an opto-navigation system

Koji Yamamoto, Yuki Maeda, Yasuo Masaki, Keiichiro Kagawa, Masahiro Nunoshita, Jun Ohta

Proceedings Volume 5677, (2005) https://doi.org/10.1117/12.596755

KEYWORDS: Image sensors, Sensors, CMOS sensors, Cell phones, Visualization, Human-machine interfaces, CMOS technology, Data communications, Image resolution, Imaging systems

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Proceedings Article | 7 March 2005 Paper

Pulse modulation image sensors for on-chip bioimaging and biosensing applications

Takashi Tokuda, David Ng, Hideki Okamoto, Keiichiro Kagawa, Jun Ohta, Masahiro Nunoshita

Proceedings Volume 5677, (2005) https://doi.org/10.1117/12.588168

KEYWORDS: Modulation, Image sensors, Biosensing, Sensors, Amplifiers, In vitro testing, Luminescence, In vivo imaging, Neuroimaging, Brain

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Proceedings Article | 7 March 2005 Paper

A 0.9-V pulse frequency modulation photosensor based on capacitive feedback reset

Koutaro Yasuoka, Keiichiro Kagawa, Jun Ohta, Masahiro Nunoshita

Proceedings Volume 5677, (2005) https://doi.org/10.1117/12.588226

KEYWORDS: Photodiodes, Transistors, Power supplies, Capacitance, High dynamic range imaging, Frequency modulation, Eye, CMOS technology, Sensors, Image sensors

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Proceedings Article | 7 June 2004 Paper

A 16 x 16-pixel retinal-prosthesis vision chip with in-pixel digital image processing in a frequency domain by use of a pulse-frequency-modulation photosensor

Keiichiro Kagawa, Tetsuo Furumiya, David Ng, Akihiro Uehara, Jun Ohta, Masahiro Nunoshita

Proceedings Volume 5301, (2004) https://doi.org/10.1117/12.526693

KEYWORDS: Digital image processing, Digital electronics, Image processing, Digital electronic circuits, Amplifiers, Sensors, Cameras, Imaging systems, Digital photography, Electronic imaging

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We are exploring the application of pulse-frequency-modulation (PFM) photosensor to retinal prosthesis for the blind because behavior of PFM photosensors is similar to retinal ganglion cells, from which visual data are transmitted from the retina toward the brain. We have developed retinal-prosthesis vision chips that reshape the output pulses of the PFM photosensor to biphasic current pulses suitable for electric stimulation of retinal cells. In this paper, we introduce image-processing functions to the pixel circuits. We have designed a 16x16-pixel retinal-prosthesis vision chip with several kinds of in-pixel digital image processing such as edge enhancement, edge detection, and low-pass filtering. This chip is a prototype demonstrator of the retinal prosthesis vision chip applicable to in-vitro experiments. By utilizing the feature of PFM photosensor, we propose a new scheme to implement the above image processing in a frequency domain by digital circuitry. Intensity of incident light is converted to a 1-bit data stream by a PFM photosensor, and then image processing is executed by a 1-bit image processor based on joint and annihilation of pulses. The retinal prosthesis vision chip is composed of four blocks: a pixels array block, a row-parallel stimulation current amplifiers array block, a decoder block, and a base current generators block. All blocks except PFM photosensors and stimulation current amplifiers are embodied as digital circuitry. This fact contributes to robustness against noises and fluctuation of power lines. With our vision chip, we can control photosensitivity and intensity and durations of stimulus biphasic currents, which are necessary for retinal prosthesis vision chip. The designed dynamic range is more than 100 dB. The amplitude of the stimulus current is given by a base current, which is common for all pixels, multiplied by a value in an amplitude memory of pixel. Base currents of the negative and positive pulses are common for the all pixels, and they are set in a linear manner. Otherwise, the value in the amplitude memory of the pixel is presented in an exponential manner to cover the wide range. The stimulus currents are put out column by column by scanning. The pixel size is 240um x 240um. Each pixel has a bonding pad on which stimulus electrode is to be formed. We will show the experimental results of the test chip.

Proceedings Article | 19 November 2003 Paper

Pulse-frequency-modulation vision chip with frequency range control as a retinal prosthesis device

Tetsuo Furumiya, Akihiro Uehara, Keiichi Isakari, Norikatsu Yoshida, Keiichiro Kagawa, Jun Ohta, Masahiro Nunoshita

Proceedings Volume 4829, (2003) https://doi.org/10.1117/12.527528

KEYWORDS: Retina, Transistors, Control systems, Frequency modulation, Visualization, Modulation, Power supplies, Photodiodes, Filtering (signal processing), Optical fabrication

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Proceedings Article | 16 May 2003 Paper

Demonstration of a frequency-demodulation CMOS image sensor

Koji Yamamoto, Keiichiro Kagawa, Jun Ohta, Masahiro Nunoshita, Yasushi Yamasaki, Kunihiro Watanabe

Proceedings Volume 5017, (2003) https://doi.org/10.1117/12.476788

KEYWORDS: Modulation, Sensors, Image sensors, Light emitting diodes, Signal detection, CMOS sensors, CMOS technology, Diffusion, Signal generators, Light sources

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Proceedings Article | 16 May 2003 Paper

CMOS image sensor working as high-speed photo receivers as well as a position sensor for indoor optical wireless LAN systems

Keiichiro Kagawa, Tomohiro Nishimura, Hiroaki Asazu, Tomoaki Kawakami, Jun Ohta, Masahiro Nunoshita, Yasushi Yamasaki, Kunihiro Watanabe

Proceedings Volume 5017, (2003) https://doi.org/10.1117/12.476785

KEYWORDS: Image sensors, Local area networks, Optical amplifiers, Photodiodes, Optical communications, Amplifiers, CMOS sensors, Telecommunications, Copper indium disulfide, Wireless communications

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Proceedings Article | 16 May 2003 Paper

System implementation of a CMOS vision chip for visual recovery

Akihiro Uehara, David Ng, Tetsuo Furumiya, Keiichi Isakari, Keiichiro Kagawa, Takashi Tokuda, Jun Ohta, Masahiro Nunoshita

Proceedings Volume 5017, (2003) https://doi.org/10.1117/12.476789

KEYWORDS: Sensors, Retina, Signal processing, Neurons, Visualization, Prototyping, Capacitors, Tissues, Electrodes, Signal detection

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Proceedings Article | 24 April 2002 Paper

Image sensor based on pulse frequency modulation for retinal prosthesis

Jun Ohta, Norikatsu Yoshida, Tetsuo Furumiya, Keiichiro Kagawa, Masahiro Nunoshita

Proceedings Volume 4669, (2002) https://doi.org/10.1117/12.463450

KEYWORDS: Frequency modulation, Photodiodes, Image sensors, Power supplies, CMOS technology, Retina, Transistors, CMOS sensors, Capacitance, Electrodes

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Proceedings Article | 30 October 2001 Paper

Application of pulse frequency modulation photosensors to subretinal artificial retina implantation

Keiichiro Kagawa, Norikatsu Yoshida, Tetsuo Furumiya, Jun Ohta, Masahiro Nunoshita

Proceedings Volume 4596, (2001) https://doi.org/10.1117/12.447359

KEYWORDS: Retina, Frequency modulation, Digital electronics, Photodetectors, Photodiodes, Diodes, CMOS technology, Digital electronic circuits, Power supplies, Modulation

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Proceedings Article | 24 May 2000 Paper

Optoelectronic parallel-matching architecture for global parallel processing: experiments

Keiichiro Kagawa, Kouichi Nitta, Jun Tanida, Yoshiki Ichioka

Proceedings Volume 4089, (2000) https://doi.org/10.1117/12.386844

KEYWORDS: Phase modulation, Prototyping, Computer architecture, Parallel computing, Optoelectronics, Optical interconnects, Vertical cavity surface emitting lasers, Data communications, Computer generated holography, Computing systems

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Proceedings Article | 22 May 1998 Paper

Optoelectronic parallel-matching architecture: concept and design

Keiichiro Kagawa, Jun Tanida, Yoshiki Ichioka

Proceedings Volume 3490, (1998) https://doi.org/10.1117/12.308905

KEYWORDS: Computer architecture, Optoelectronics, Parallel computing, Computing systems, Data communications, Data processing, Databases, Fiber optic communications, Computer generated holography, Point spread functions

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Proceedings Article | 1 September 1996 Paper

Photofabrication in optical system fabrication

Keiichiro Kagawa

Proceedings Volume 2778, 277879 (1996) https://doi.org/10.1117/12.2299144

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