研究者詳細 - 野村　孝徳

講演・口頭発表等 - 野村　孝徳

分割表示44 件中 21 - 40 件目／全件表示 >>

Numerical evaluation of transport-of-intensity phase imaging with oblique illumination for refractive index tomography

Koshi Komuro, Yusuke Saita, Yosuke Tamada, Takanori Nomura

Proceedings Digital Holography and Three-Dimensional Imaging 2019 2019年05月13日

Phase imaging in-line digital holography with random phase modulation

Takanori Nomura

Proceedings of SPIE - The International Society for Optical Engineering 2019年 SPIE-INT SOC OPTICAL ENGINEERING

In-line digital holography using a random phase modulation is proposed. Owing to the random phase modulation, twin-image problem inherent to the in-line optical setup is relieved. Furthermore, because no multiplexed recording is required, dynamic phenomena can be recorded. This idea is inspired by double-random phase- encryption. The difference between the proposed method and the double-random phase-encryption is brie y described. Preliminary experimental results confirm the feasibility of the proposed method. The difference of coherence of a light source is also discussed.

Computer-generated-hologram-based holographic data storage using a transport of intensity equation

Naru Yoneda, Yusuke Saita, Koshi Komuro, Teruyoshi Nobukawa, Takanori Nomura

Optics InfoBase Conference Papers 2018年

Utilization of phase information can increase the recording density of holographic data storage. In this paper, a transport of intensity equation is introduced to computer-generated-hologram-based holographic data storage, which can obtain the phase datapage while keeping an optical setup simple and compact. Moreover, two defocused intensity distributions for the transport of intensity equation can be simultaneously obtained by using a conjugate beam from the computer-generated hologram.

Deep-learning-based phase retrieval for pure phase objects in computational ghost imaging

Koshi Komuro, Alexandre Goy, Takanori Nomura, George Barbastathis

Optics InfoBase Conference Papers 2018年

Random amplitude or phase modulation for three-dimensional sensing and imaging

Takanori Nomura

Proceedings of SPIE - The International Society for Optical Engineering 2018年 SPIE-INT SOC OPTICAL ENGINEERING

Three-dimensional imaging is very attractive for biomedical fields, industrial inspecting, and so on. Computational optical sensing and imaging is widely studied due to the recent development of imaging device, computational power, and so on. It is also used for three-dimensional sensing and imaging. In this area, random amplitude or phase modulation is introduced to improve its performance. In this paper, computational ghost imaging using a designed random amplitude modulation is presented. Owing to the designed random amplitude modulation, the number of measurements can be reduced. A phase modulation for twin image reduction of in-line digital holography is also presented. Owing to the random phase modulation, the overlapping an object image and its conjugate image can be reduced.

Single-shot in-line digital holography without twin image

Takanori Nomura

Proceedings of SPIE - The International Society for Optical Engineering 2018年 SPIE-INT SOC OPTICAL ENGINEERING

In-line digital holography is conventional but still attractive because of its simple optical setup. In general, sequential phase-shifting technique is mandatory to remove twin-image which makes the reconstructed image quality low. However, sequential phase-shifting technique requires multiple recording. Multiple recording means that it is not suitable for a dynamic phenomenon. In this paper, two kinds of a single-shot in-line digital holography without twin-image using a diffused illumination are presented. One is a generalized phase-shifting digital holography and the other is a computational removal of twin-image. The ideas and their experimental results are given to confirm the feasibility.

Transport of intensity phase imaging for pure phase objects in computational ghost imaging

Koshi Komuro, Yuya Yamazaki, Takanori Nomura

Proceedings of SPIE - The International Society for Optical Engineering 2018年 SPIE-INT SOC OPTICAL ENGINEERING

Computational ghost imaging (CGI) is expected to be applied to noninvasive biomedical imaging because of its characteristic which allows us to obtain the object's image under a low signal to noise ratio (SNR) condition. However only an amplitude distribution can be obtained by the CGI. Therefore the imaging of the pure phase objects is difficult. Although the phase shifting digital holography has been used for reconstruction of the complex amplitude in the CGI, its experimental setup is cumbersome and sensitive to vibrations. Furthermore four holograms are required for the reconstruction of the complex amplitude because of the phase shifting algorithm, rendering the acquisition time of the phase image slow. Therefore the method is difficult to be applied to the biomedical imaging. An alternative non-interferometric method is proposed in this study. The proposed method uses the transport of intensity equation for the phase retrieval of the pure phase objects, termed transport-of-intensity CGI (TI-CGI). In the TI-CGI, the phase distribution is retrieved from a single defocused image obtained by a modulated optical setup of the CGI, achieving the fast and robust imaging compared with the conventional phase shifting method. Therefore the TI-CGI may be more suitable for the biomedical imaging than the phase shifting method. The TI-CGI is demonstrated by an optical experiment under the low SNR condition generated by the neutral density filters with 1% and 0.1% transmittance. The experimental results conform the effectiveness of the TI-CGI.

Large dynamic range wavefront sensing using Shack-Hartmann wavefront sensor based on pattern correlations

Saita Yusuke, Nomura Takanori

OPTICAL DESIGN AND TESTING VIII 2018年 SPIE-INT SOC OPTICAL ENGINEERING

Wavefront sensing techniques are mainly needed in an adaptive optics system for high resolution imaging. One of them is a Shack-Hartmann method which is composed of very simple structure. Although the method is widely utilized, it also has the limitation for the measurable magnitude of wavefront aberrations. To overcome the problem, the improved Shack-Hartmann method for larger aberrated wavefronts has been proposed. In this paper, the principle of the proposed method and the numerical evaluation of the performance of the proposed method are presented.

Multimodal Imaging Based on Digital Holography

Osamu Matoba, Xiangyu Quan, Peng Xia, Yasuhiro Awatsuji, Takanori Nomura

Proceedings of the IEEE 2017年05月 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Digital holography provides a method of the 3-D recording and numerical reconstruction by a simple optical system and a computer. Quantitative measurement and numerical refocusing are major characteristics. So far, many physical parameters such as amplitude, phase, polarization, fluorescence, and spectra can be obtained independently. Recently, multimodal imaging that can obtain simultaneously two or more physical parameters by combining digital holographic microscope and other optical microscopes such as a fluorescence optical microscope and a Raman scattering microscope has emerged. In this review, physical parametric imaging techniques based on digital holography are presented and then these techniques are enhanced to develop multimodal imaging based on digital holography.

Spatially incoherent Fourier digital holography

Takanori Nomura, Kaho Watanabe

Proceedings of SPIE - The International Society for Optical Engineering 2017年 SPIE-INT SOC OPTICAL ENGINEERING

The possibility of incoherent digital holography has been widely studied because it is free from coherent light sources. Here spatially incoherent Fourier digital holography is described. The incoherent hologram is obtained by a rotational shearing interferometer. The hologram obtained by the interferometer is a cosine transform of a spatially incoherent object. After describing the principle of a rotational shearing interferometer, methods to obtain Fourier transform of an object presented.

Phase object mapping based on a complex amplitude measurement by transport of intensity equation

Koshi Komuro, Takanori Nomura

Optics InfoBase Conference Papers 2017年 OSA - The Optical Society

カラー撮像素子を用いた3バンド像面フーリエ分光映像法

谷口祐太, 野村孝徳

応用物理学会学術講演会講演予稿集 2016年09月01日公益社団法人応用物理学会

Holographic storage system based on digital holography for recording a phase data page in a compact optical setup

Teruyoshi Nobukawa, Takanori Nomura

PRACTICAL HOLOGRAPHY XXX: MATERIALS AND APPLICATIONS 2016年 SPIE-INT SOC OPTICAL ENGINEERING

A holographic storage system based on digital holography is proposed for recording and retrieving a phase data page in a compact and simple optical setup. In the proposed recording system, complex amplitude distribution can be modulated using a single phase-only spatial light modulator. The complex amplitude distribution of a retrieved phase data page is detected with the Fourier fringe analysis. The use of digital holographic techniques enables realizing a compact and simple holographic recording system, which is independent of misalignment problem in conventional holographic storage systems. The capability of the proposed recording system is numerically and experimentally evaluated.

Incoherent holography by a Michelson type interferometer with a lens for a radial shear

Kaho Watanabe, Takanori Nomura

THREE-DIMENSIONAL IMAGING, VISUALIZATION, AND DISPLAY 2016 2016年 SPIE-INT SOC OPTICAL ENGINEERING

The modified Michelson type interferometer with lenses for a radial shear to record incoherent holograms is proposed. It enables us to record a hologram by self-interference without coherent illumination such as a laser. The interferometer has two wave plates which can realize phase-shifting incoherent holography. The feature can avoid a very large bias term and the twin image, which are the inherent problem of incoherent holography by self-interference. The advantages of the proposed method using lenses and wave plates are easy adjustment of the zone plate and simplification of the optical system. A preliminary experiment using an LED as an incoherent object was performed to confirm the four step phase-shifting by wave plates.

Numerical evaluation of shift multiplexing using a spherical wave in a holographic memory based on a computer-generated hologram

Teruyoshi Nobukawa, Takanori Nomura

OPTICAL DATA STORAGE 2016 2016年 SPIE-INT SOC OPTICAL ENGINEERING

Shift multiplexing method using a spherical wave is proposed for a holographic memory system based on a computer-generated hologram (CGH). In the proposed method, a propagated signal beam along an optical axis is generated by a CGH. The zero order beam of the CGH is obtained as a point source in the Fourier plane. This point source becomes a spherical reference beam on a recording medium by displacing a Fourier transform lens. The use of the spherical reference beam allows us to implement shift multiplexing in the holographic memory based on a CGH. Shift selectivity of the proposed method is numerically evaluated. In addition, shift multiplexing with the proposed method is numerically demonstrated.

Generalized phase-shifting color digital holography

Takanori Nomura, Takaaki Kawakami, Kazuma Shinomura

THREE-DIMENSIONAL IMAGING, VISUALIZATION, AND DISPLAY 2016 2016年 SPIE-INT SOC OPTICAL ENGINEERING

Two methods to apply the generalized phase-shifting digital holography to color digital holography are proposed. One is wave-splitting generalized phase-shifting color digital holography. This is realized by using a color Bayer camera. Another is multiple exposure generalized phase-shifting color digital holography. This is realized by the wavelength-dependent phase-shifting devices. Experimental results for both generalized phase-shifting color digital holography are presented to confirm the proposed methods.

Holographic Data Storage by Use of Computer Generated Hologram

Nomura, Takanori, Nobukawa, Teruyoshi

2016 ASIA COMMUNICATIONS AND PHOTONICS CONFERENCE (ACP) 2016年 IEEE

Arbitrary pattern in an arbitrary domain can be realized by computer generated hologram (CGH). If CGH is applied to the optical data storage, the complexity of the optical system can be eased. For example, a single spatial light modulator (SLM) can be used to express a fully-complex filed of a lightwave. Holographic data storage with a single amplitude SLM by use of CGH is presented. A signal beam and a reference beam are generated by a computer generated hologram (CGH). Owing to the characteristics of the CGH, the incident angle of a reference beam can be changed. This means that angular multiplexing is available.

Generalized phase-shifting digital holography for single-exposure

Takanori Nomura, Masatoshi Imbe

INTERNATIONAL CONFERENCE ON PHOTONICS SOLUTIONS 2015 2015年 SPIE-INT SOC OPTICAL ENGINEERING

Single exposure phase-shifting digital holography is mandatory for recording/analyzing dynamic phenomena. As one of the candidate for the single exposure phase-shifting digital holography is the wave-splitting phase-shifting digital holography. We have proposed generalized phase-shifting digital holography as one of the wave-splitting phase-shifting digital holography. In the digital holography, the phase-shift quantity, which corresponds to the difference between the phase quantities of the reference wave on the adjacent pixels is generalized different from ordinal wave-splitting methods. Owing to the generalized phase-shifting, we can use a random-phase wave as the reference wave. The proposed phase-shifting digital holography enables us to record a fully-complex field of a dynamic phenomena without dc and conjugate terms using a commercially available optical devices. The relation between the property of the reference wave and the quality of the reconstructed images are discussed. Experimental results are given to confirm the proposed phase-shifting digital holography.

Expansion of dynamic range in Shack-Hartmann wavefront sensor using dual microlens array

Hironobu Shinto, Yusuke Saita, Takanori Nomura

Progress in Biomedical Optics and Imaging - Proceedings of SPIE 2015年 SPIE

A Shack-Hartmann wavefront sensor (SHWFS) which consists of a microlens array and an image sensor has been used to measure the wavefront aberrations in various fields owing to its advantages such as simple configuration. However, a conventional SHWFS has the finite dynamic range. The dynamic range cannot be expanded without sacrificing the spatial resolution and the sensitivity in a conventional SHWFS. In this study, the SHWFS using a dual microlens array to solve the problem is proposed. In the proposed method, an astigmatic microlens is arranged at the center of a group of 2 x 2 spherical microlenses. A pattern image including spots and linear patterns is obtained at the focal plane by the dual microlens array. The pattern image can be separated into two images as if two microlens array with different diameter were used by discriminating spots from linear patterns with the pattern matching technique. The proposed method enables to expand the dynamic range of an SHWFS by using the separated two images. The performance of the proposed method is confirmed by the numerical simulation for measuring a spherical wave.

Mueller matrix imaging by use of digital holography

Takanori Nomura, Toshitaka Kobata

2015 INTERNATIONAL CONFERENCE ON OPTICAL INSTRUMENTS AND TECHNOLOGY: OPTOELECTRONIC MEASUREMENT TECHNOLOGY AND SYSTEMS 2015年 SPIE-INT SOC OPTICAL ENGINEERING

A Mueller matrix imaging method by use of the characteristics of digital holography is proposed. In the proposed method, only two exposures are required to obtain the Mueller matrix. The Mueller matrix can be calculated from Stokes vectors. Stokes vectors can be obtained from two fully-complex amplitude distributions. Fully complex amplitude distributions can be obtained by digital holography. The optical experiments by using two kinds of specimens which are four linear polarizers and a quarter wave plate are shown to demonstrate the proposed method.

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講演・口頭発表等 - 野村 孝徳

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講演・口頭発表等 - 野村　孝徳