論文 - 似内　映之

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]

　概要を見る

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

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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]

　概要を見る

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.

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Improvement of viewing-zone angle and image quality of digital holograms

Takanori Nomura, Yusuke Teranishi, Eiji Nitanai, Takuhisa Numata

Information Optics and Photonics: Algorithms, Systems, and Applications ( Springer New York )    155 - 161   2010年

　概要を見る

A method to improve the viewing-zone angle and the 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 our proposed method. © 2010 Springer Science+Business Media, LLC.

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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

　概要を見る

The both profilemotry and reflectmetry of a 3D object by use of digital holography with low coherent light source is proposed. For noise reduction, integration of digital holograms is introduced. © 2010 Optical society of America.

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Quasi-cylindrical digital hologram by superposition of digital holograms recorded on concyclic positions

Takanori Nomura, Yusuke Teranishi, Eiji Nitanai, Takuhisa Numata

Optics InfoBase Conference Papers ( Optical Society of America (OSA) )    2009年

　概要を見る

The method to generate a quasi-cylindrical digital hologram is presented. A number of digital holograms of an central object recorded on concyclic positions are used for superposition. The superposition is achieved by numerical propagation of the hologram. Some experimental results are shown to confirm our proposed method. © 2009 Optical society of America.

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Image quality improvement of digital holography by superposition of reconstructed images obtained by multiple wavelengths

Takanori Nomura, Mitsukiyo Okamura, Eiji Nitanai, Takuhisa Numata

APPLIED OPTICS ( OPTICAL SOC AMER )  47 ( 19 ) D38 - D43   2008年07月  [査読有り]

　概要を見る

A method to improve the image quality of a digital holographic reconstructed image by means of speckle reduction is proposed. The size and position of the speckles are changed according to the wavelengths to record a digital hologram. By superposing reconstructed images with different wavelengths, the effect of speckle is reduced so that the image quality is improved. Optical experiments are given to confirm the proposed method. (c) 2008 Optical Society of America

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Image quality improvement of digital holography by superposition of reconstructed images obtained by multiple wavelengths

Takanori Nomura, Mitsukiyo Okamura, Eiji Nitanai, Takuhisa Numata

Applied Optics   47 ( 19 ) D38   2008年  [査読有り]

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Polarization imaging of a 3D object by use of on-axis phase-shifting digital holography

Takanori Nomura, Bahram Javidi, Shinji Murata, Eiji Nitanai, Takuhisa Numata

OPTICS LETTERS ( OPTICAL SOC AMER )  32 ( 5 ) 481 - 483   2007年03月  [査読有り]

　概要を見る

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. (c) 2007 Optical Society of America.

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Wave-splitting phase-shifting digital holography by use of a retarder array

Takanori Nomura, Eiji Nitanai, Takuhisa Numata

2007 IEEE LEOS ANNUAL MEETING CONFERENCE PROCEEDINGS, VOLS 1 AND 2 ( IEEE )    82 - 83   2007年  [査読有り]

　概要を見る

The phase-shifting digital holography by use of a micro-retarder array is proposed. The micro-retarder array consists of four kinds of different directions of fast axes. The combination of the micro-retarder array and a polarizer gives us the four intensity distributions corresponding to the direction of the fast axes. From four intensity images,we can calculate Stokes parameters of the incident wave. Furthermore, we can obtain fully-complex amplitude distribution of the object wave by using Stokes parameters, if the both polarization states of the object wave and the reference wave are linear and they are orthogonal. Some experimental results are given to confirm our proposed recording method.

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Polarimetric Imaging of a three-dimensional object by use of digital holography

Takanorl Nomura, Bahrain Javidi, Shinji Murata, Eiji Nitanai, Takuhisa Numata

6TH INTERNATIONAL WORKSHOP ON INFORMATION OPTICS (WIO '07) ( AMER INST PHYSICS )  949   107 - +   2007年  [査読有り]

　概要を見る

A polarimetric imaging method of a 3D object by use of digital holography is presented. The phase-shifitng digital holography using orthogonal polarization is adopted. 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.

Phase-shifting digital holography with a phase difference between orthogonal polarizations

Takanori Nomura, Shinji Murata, Eiji Nitanai, Takuhisa Numata

APPLIED OPTICS ( OPTICAL SOC AMER )  45 ( 20 ) 4873 - 4877   2006年07月  [査読有り]

　概要を見る

Phase-shifting digital holography with a phase difference between orthogonal polarizations is proposed. The use of orthogonal polarizations can make it possible to record two phase-shifted holograms simultaneously. By combining the holograms with the distributions of a reference wave and an object wave, the complex field of the object's wavefront can be obtained. Preliminary experimental results are shown to confirm the proposed method. (C) 2006 Optical Society of America.

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Design of input phase mask for the space bandwidth of the optical encryption system

T Nomura, E Nitanai, T Numata, B Javidi

OPTICAL ENGINEERING ( SPIE-INT SOCIETY OPTICAL ENGINEERING )  45 ( 1 )   2006年01月  [査読有り]

　概要を見る

A method to design an input phase mask for double-random phase-encoding optical encryption is proposed. The input phase mask is iteratively designed so that the extent of the Fourier spectrum of the product of an input image and the input phase mask correspond to the space bandwidth of the optical system. By using the designed input phase mask, we show that the bit-error rate is improved. We also discuss the number of phase levels of the designed input phase mask. (c) 2006 Society of Photo-Optical Instrumentation Engineers.

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One-shot digital holography by use of polarization

Takanori Nomura, Bahram Javidi, Shinji Murata, Eiji Nitanai, Takuhisa Numata

OPTICAL INFORMATION SYSTEMS IV ( SPIE-INT SOC OPTICAL ENGINEERING )  6311   2006年  [査読有り]

　概要を見る

The one-shot phase-shifting digital holography using phase difference of orthogonal polarizations is proposed. Using a CCD camera with pixelated polarizers, three images for phase analysis can be obtained simultaneously. The proposed method can be applied to a moving object, because a complex field of the wavefront of a 3D object can be obtained in a single exposure.

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Speckles removal in digital holography using multiple wavelengths/distances from an object

Takanori Nomura, Mitsukiyo Okamura, Eiji Nitanai, Takuhisa Numata

2006 IEEE LEOS ANNUAL MEETING CONFERENCE PROCEEDINGS, VOLS 1 AND 2 ( IEEE )    74 - +   2006年  [査読有り]

　概要を見る

The method to reduce speckles in a reconstructed image of a digital hologram is proposed. The size and position of the speckles are changed according to both the wavelengths to be recorded and the distances from the object the hologram. The superposition of the reconstructed images recorded with different wavelength/distance holograms gives the image with reduced speckles.

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Optical encryption using an input phase mask designed for the space bandwidth of the optical system

T Nomura, T Fujita, E Nitanai, T Numata, B Javidi

2004 IEEE LEOS ANNUAL MEETING CONFERENCE PROCEEDINGS, VOLS 1 AND 2 ( IEEE )    344 - 345   2004年  [査読有り]

　概要を見る

The method to design an input phase mask for the double-random phase-encoding optical encryption is proposed. The input phase;mask is designed so that the extend of the Fourier spectrum of the product of an input image and the input phase mask corresponds to the space bandwidth of the optical system. By using the designed input phase mask, we show that the bit-error rate is improved.

Irradiation-dependent saturable absorption properties in dye-doped polyvinyl alcohol films exposed to a highly humid atmosphere

E Nitanai, S Miyanaga (担当区分： 筆頭著者 )

OPTICAL REVIEW ( OPTICAL SOC JAPAN )  5 ( 1 ) 43 - 47   1998年01月  [査読有り]

　概要を見る

Effects of humidity on nonlinear transmission properties due to saturable absorption were investigated using eosin-Y-doped polyvinyl alcohol (PVA) films which had been exposed to a highly humid atmosphere. In a pump-probe measurement, a transmitted probe signal changed in every shot of the pump-pulse irradiation, and tended to approach a steady characteristic. Simultaneous measurements of the transmitted probe power and the phosphorescent lifetime showed that these phenomena stem from the phosphorescent lifetime being lengthened by the successive pump irradiations. This increase in lifetime was found to have originated from reduction of a nonradiative decay rate of an excited state of the dyes. The recurrent pump irradiations are believed to remove moisture, which has strengthened the nonradiative decay rate, from the PVA films.

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Measurements of dispersion properties of refractive indices and absorption coefficients in organic-dye-doped thin films by a prism-coupling method

E Nitanai, S Miyanaga (担当区分： 筆頭著者 )

OPTICAL ENGINEERING ( SOC PHOTO-OPT INSTRUM ENG )  35 ( 3 ) 900 - 903   1996年03月  [査読有り]

　概要を見る

Refractive indices and thicknesses of organic-dye-doped thin films are measured by a prism-coupling method. Anomalous dispersion of refractive indices which is caused by absorption of dyes, can be observed. The measured film thicknesses are used to determine the absorption coefficients of those films together with transmission measurements. In a highly absorptive wavelength region, the accuracy of measurements is decreased as a consequence of the broadening of m line corresponding to each guided mode. From the measurements in eosin-Y-doped polymer films, it is found that this method is not available when transmission is less than about 80%. (C) 1996 Society of Photo-Optical Instrumentation Engineers.

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