研究者詳細 - 野村　孝徳

論文 - 野村　孝徳

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Complex amplitude-modulated data page recording in coaxial holographic data storage with phase-shifting digital holography

Teruyoshi Nobukawa, Takanori Nomura

Optics InfoBase Conference Papers ( Optical Society of American (OSA) ) 2014年

Complex amplitude-modulated data page recording in coaxial holographic data storage with phase-shifting digital holography

Teruyoshi Nobukawa, Takanori Nomura

Optics InfoBase Conference Papers ( Optical Society of American (OSA) ) 2014年

Complex amplitude-modulated data page recording in coaxial holographic data storage with phase-shifting digital holography

Teruyoshi Nobukawa, Takanori Nomura

Optics InfoBase Conference Papers ( Optical Society of American (OSA) ) 2014年

Complex amplitude-modulated data page recording in coaxial holographic data storage with phase-shifting digital holography

Teruyoshi Nobukawa, Takanori Nomura

Optics InfoBase Conference Papers ( Optical Society of American (OSA) ) 2014年

Complex amplitude-modulated data page recording in coaxial holographic data storage with phase-shifting digital holography

Teruyoshi Nobukawa, Takanori Nomura

Optics InfoBase Conference Papers ( Optical Society of American (OSA) ) 2014年

Shortening method for optical reconstruction distance in digital holographic display with phase hologram

Mori Yutaka, Nomura Takanori

OPTICAL ENGINEERING ( SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS ) 52 ( 12 ) 2013年12月 [査読有り]

We present a method to solve a distance issue. In digital holography, the reconstruction distance is different from the original one because of the difference of the pixel size between an imaging device and a display device. In general, the distance is larger because the pixel size of the display is larger than that of the imaging device. This makes it hard to recognize perception of the stereoscopic effect when holographic reconstructed images are used for the stereopsis system. Typically, a numerical propagation method and a spherical phase addition are used to shorten the distance. However, each method is not shortened enough. To clear the criterion, the limitation of each method is verified. By combining two methods, the reconstruction distance is shortened from 4440 to 547 mm. In addition, it is successfully shown that the proposed combining method is useful for the stereopsis by visual perception evaluation. (C) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)

DOI

Coaxial Holographic Memory with Designed Reference Pattern on the Basis of Nyquist Aperture for High Density Recording

Teruyoshi Nobukawa, Takanori Nomura

JAPANESE JOURNAL OF APPLIED PHYSICS ( IOP PUBLISHING LTD ) 52 ( 9 ) 2013年09月 [査読有り]

We propose the designed reference pattern on the basis of the Nyquist aperture for a coaxial holographic memory and investigate its recording performance by numerical simulations. By using the designed reference pattern, the Fourier power spectrum of a reference beam spreads uniformly within the Nyquist aperture, thereby an interference efficiency, a signal-to-noise ratio (SNR) and a symbol error rate (SER) are improved relative to conventional method with a random binary phase mask. Moreover, in the case of applying the 1.25 times aperture than the Nyquist size, the proposed method can record data pages with higher SNR and lower SER than that of conventional method with 2 times aperture than the Nyquist size. Numerical results imply that our proposed method can record data pages at a smaller area of recording media than that of conventional method. (c) 2013 The Japan Society of Applied Physics

DOI

Study of reference waves in single-exposure generalized phase-shifting digital holography

Masatoshi Imbe, Takanori Nomura

APPLIED OPTICS ( OPTICAL SOC AMER ) 52 ( 18 ) 4097 - 4102 2013年06月 [査読有り]

The appropriate reference wave in single-exposure phase-shifting digital holography using a random-complex-amplitude encoded reference wave is experimentally investigated. Although the reference wave is generalized, the quality of reconstructed images depends on it. Furthermore, when the reference wave satisfies a certain condition, reconstructed images cannot be obtained in this method. After the certain condition is presented, the appropriate condition is studied using a speckle property. Experimental results are given to investigate the relations between the quality of reconstructed images and the sizes of speckles of the reference waves. The results prove that the appropriate reference wave exists in this method. (C) 2013 Optical Society of America

DOI

Synthesis method from low-coherence digital holograms for improvement of image quality in holographic display

Mori Yutaka, Nomura Takanori

APPLIED OPTICS ( OPTICAL SOC AMER ) 52 ( 16 ) 3838 - 3844 2013年06月 [査読有り]

In holographic displays, it is undesirable to observe the speckle noises with the reconstructed images. A method for improvement of reconstructed image quality by synthesizing low-coherence digital holograms is proposed. It is possible to obtain speckleless reconstruction of holograms due to low-coherence digital holography. An image sensor records low-coherence digital holograms, and the holograms are synthesized by computational calculation. Two approaches, the threshold-processing and the picking-a-peak methods, are proposed in order to reduce random noise of low-coherence digital holograms. The reconstructed image quality by the proposed methods is compared with the case of high-coherence digital holography. Quantitative evaluation is given to confirm the proposed methods. In addition, the visual evaluation by 15 people is also shown. (C) 2013 Optical Society of America

DOI

Single-exposure phase-shifting digital holography using a random-complex-amplitude encoded reference wave

Masatoshi Imbe, Takanori Nomura

APPLIED OPTICS ( OPTICAL SOC AMER ) 52 ( 1 ) A161 - A166 2013年01月 [査読有り]

The improved single-exposure phase-shifting digital holography using a random-phase reference wave is proposed. The algorithm for obtaining a complex amplitude of an object wave is improved. In the proposed algorithm, the reference wave is treated as not a random-phase but a random-complex amplitude. Therefore, the algorithm uses proper amplitude information of the reference wave. Both numerical simulations and experimental results are given to confirm the effectiveness of the proposed algorithm. (C) 2012 Optical Society of America

DOI

Digital holographic tomography using a light back propagation method and its application for refractive index measurement

Nomura Takanori, Kitazawa Takahiro

OPTICS AND PHOTONICS FOR INFORMATION PROCESSING VII ( SPIE-INT SOC OPTICAL ENGINEERING ) 8855 2013年 [査読有り]

A lensless digital holographic tomography using not a filtered back projection method but a light back propagation method is proposed. In the proposed method, the phase distribution on the detector is used for a light propagation. On the contrary, in the conventional method, the phase information is used for a back projection. Owing to the propagation, the deflection from a true optical path is reduced in the proposed method. For the measurement of a specimen with a huge refraction angle, it is shown that our proposed method improves on measurement accuracy compared with a conventional filtered back projection method. Numerical simulations are given to confirm the feasibility of the proposed method.

DOI

Refractive Index & Physical Thickness Distributions Measurement and Consideration of Dependence of Measurement Accuracy on Scanning Interval Using Low-Coherence Digital Holography

Kaho Watanabe, Takanori Nomura

2013 IEEE/SICE INTERNATIONAL SYMPOSIUM ON SYSTEM INTEGRATION (SII) ( IEEE ) 586 - 591 2013年 [査読有り]

The measurement method of a refractive index distribution and a physical thickness distribution using digital holography with a low-coherent light source is proposed. The introduction of a datum plane enables the simultaneous measurement of a refractive index and a physical thickness distributions. By the optical experiments, the potential of the proposed method is confirmed. For the reduction of measurement time, the relation between stepping intervals of a reference mirror and measurement results are also discussed.

Design of Reference Pattern and Input Phase Mask for Coaxial Holographic Memory

Yusuke Saita, Takanori Nomura, Eiji Nitanai, Takuhisa Numata

JAPANESE JOURNAL OF APPLIED PHYSICS ( JAPAN SOC APPLIED PHYSICS ) 50 ( 9 ) 2011年09月 [査読有り]

Design methods of a reference pattern and an input phase mask for a coaxial holographic memory are described. By the proposed method, it is expected that the useless consumption of the dynamic range of a recording medium will decrease, and the light efficiency and the interference efficiency between the signal beam and the reference beam will be improved. A reference pattern and an input phase mask are designed by a simulated annealing. The performance of the proposed design method is confirmed by numerical simulations and optical experiments. Furthermore, the holographic memory system using both the designed reference pattern and the designed input phase mask is also confirmed by numerical simulations and optical experiments. (C) 2011 The Japan Society of Applied Physics

DOI

Single-shot phase-shifting digital holography using a conventional camera

Takanori Nomura

2011 ICO International Conference on Information Photonics, IP 2011 2011年 [査読有り]

DOI

Single-exposure phase-shifting digital holography using a random-phase reference wave

Takanori Nomura, Masatoshi Imbe

OPTICS LETTERS ( OPTICAL SOC AMER ) 35 ( 13 ) 2281 - 2283 2010年07月 [査読有り]

We propose a single-exposure phase-shifting digital holography based on a wave-splitting method using a random-phase reference wave. A random-phase reference wave gives random-phase distribution on the digital hologram. Using the amplitude and the phase distributions of the reference wave, the fully complex amplitude of the object wave is obtained. The proposed method requires not devised optical systems but ordinary imaging devices, such as CCD cameras. A preliminary experimental result is given to confirm the proposed method. (C) 2010 Optical Society of America

DOI

Dynamic recording of a digital hologram with single exposure by a wave-splitting phase-shifting method

Hiroyuki Suzuki, Takanori Nomura, Eiji Nitanai, Takuhisa Numata

OPTICAL REVIEW ( OPTICAL SOC JAPAN ) 17 ( 3 ) 176 - 180 2010年05月 [査読有り]

The wave-splitting phase-shifting digital holography using a pixelated microretarder array is proposed. By using four intensity images recorded by the pixelated microretarder array, Stokes parameters of the incident wave can be calculated. The fully complex amplitude distribution of the object wave can be obtained by using Stokes parameters, if the polarization states of the object and reference waves are linear and orthogonal. Two sets of experimental results are provided to verify the feasibility of the proposed method. One is the result for a movie recording using a CW laser and the other is the result for instant recording using a single pulsed laser.

DOI

Profilometry and reflectmetry using low-coherent digital holography

Takanori Nomura, Kohei Yoshino, Takuhisa Numata, Eiji Nitanai

Optics InfoBase Conference Papers ( Optical Society of America (OSA) ) 2010年

DOI

Improvement of Viewing-Zone Angle and Image Quality of Digital Holograms

Takanori Nomura

2009 INTERNATIONAL WORKSHOP ON INFORMATION OPTICS ( IOP PUBLISHING LTD ) 206 2010年 [査読有り]

The method to improve of a viewing-zone angle and an image quality of a digital hologram is presented. A number of digital holograms of a central object are recorded from the position on the circumference. The holograms are used for a hologram synthesis to improve the image quality from whole viewing-zone angle. The synthesis is achieved by a correlation between a hologram and numerically propagated holograms. The large-sized synthesized digital hologram has a wide viewing-zone angle and less speckles. Some experimental results are shown to confirm the proposed method.

DOI

Single-Exposure Digital Holography by a Generalized Wave-Splitting Phase-Shifting Method

Takanori Nomura

2010 9TH EURO-AMERICAN WORKSHOP ON INFORMATION OPTICS ( IEEE ) 2010年 [査読有り]

A single-exposure generalized phase-shifting digital holography based on a wave-splitting method. A phase-encoded reference wave is used for phase-shifting. Using the known amplitude and phase distributions of the reference wave, the fully complex amplitude of the object wave is obtained. The proposed method requires not devised optical systems but ordinary imaging devices, such as CCD cameras. A preliminary experimental results with a spherical wave and a random phase wave as reference waves are given to confirm the proposed method.

Polarization imaging of a 3D object by use of digital holography and its application

Takanori Nomura, Bahram Javidi

THREE-DIMENSIONAL IMAGING, VISUALIZATION, AND DISPLAY 2010 AND DISPLAY TECHNOLOGIES AND APPLICATIONS FOR DEFENSE, SECURITY, AND AVIONICS IV ( SPIE-INT SOC OPTICAL ENGINEERING ) 7690 2010年 [査読有り]

A polarimetric imaging method of a 3D object by use of on-axis phase-shifting digital holography is presented. The polarimetric image results from a combination of two kinds of holographic imaging using orthogonal polarized reference waves. Experimental demonstration of a 3D polarimetric imaging is presented. Pattern recognition by use of polarimetric phase-shifting digital holography is also presented. Using holography, the amplitude and phase difference distributions between two orthogonal polarizations of 3D phase objects are obtained. This information contains both complex amplitude and polarimetric characteristics of the object, and it can be used for improving the discrimination capability of object recognition. Preliminary experimental results are presented to demonstrate the idea.

DOI

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