論文 - 野村　孝徳

Optical Techniques for Information Security

Osamu Matoba, Takanori Nomura, Elisabet Perez-Cabre, Maria S. Millan, Bahram Javidi

PROCEEDINGS OF THE IEEE ( IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC )  97 ( 6 ) 1128 - 1148   2009年06月  [査読有り]

　概要を見る

This paper presents an overview of the potential of free space optical technology in information security, encryption, and authentication. Optical waveform posses many degrees of freedom such as amplitude, phase, polarization, spectral content, and multiplexing which can be combined in different ways to make the information encoding more secure. This paper reviews optical techniques for encryption and security of two-dimensional and three-dimensional data. Interferometric methods are used to record and retrieve data by either optical or digital holography for security applications. Digital holograms are widely used in recording and processing three dimensional data, and are attractive for securing three dimensional data. Also, we review optical authentication techniques applied to ID tags with visible and near infrared imaging. A variety of images and signatures, including biometrics, random codes, and primary images can be combined in an optical ID tag for security and authentication.

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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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Polarimetric imaging of 3-D object by use of wavefront-splitting phase-shifting digital holography

Takanori Nomura, Bahram Javidi

Three-Dimensional Imaging, Visualization, and Display ( Springer US )    333 - 344   2009年  [査読有り]

　概要を見る

A polarimetric imaging method of a 3-D object by use of wavefront-splitting phase-shifting digital holography is presented. Phase-shifting digital holography with a phase difference between orthogonal polarizations is used. The use of orthogonal polarizations can make it possible to record two phase-shifted holograms simultaneously if we use pixelated polarimetric optical elements. By combining the holograms with the distributions of a reference wave and an object wave, the complex field of the object wavefront can be obtained. The polarimetric image results from a combination of two kinds of holographic imaging using orthogonal polarized reference waves. An experimental demonstration of a 3-D polarimetric imaging is presented. © 2009 Springer-Verlag New York.

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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

Appl. Opt. ( 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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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

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

AIP Conference Proceedings   949   107 - 113   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. © 2007 American Institute of Physics.

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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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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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Design of an input phase mask of the optical encryption system and its application to certification

Takanori Nomura, Eiji Ninatai, Takuhisa Numata

INFORMATION OPTICS ( AMER INST PHYSICS )  860   481 - +   2006年  [査読有り]

　概要を見る

The secure optical memory system based on a double-random phase-encoding optical encryption system is proposed. The quality of decrypted data can be improved by designing an input phase mask to utilize the bandwidth the bandwidth of the optical system effectively. We propose the certification method of the data recorded into the optical memory by using a designed input phase mask as a phase code. Computer simulations confirm the possibility of the proposed certification system.

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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Deformation measurement by phase-shifting digital holography

Y Morimoto, T Nomura, M Fujigaki, S Yoneyama, Takahashi, I

EXPERIMENTAL MECHANICS ( SPRINGER )  45 ( 1 ) 65 - 70   2005年02月  [査読有り]

　概要を見る

The out-of-plane displacement of a cantilever is measured by phase-shifting digital holography. From four phase-shifted holograms of a cantilever recorded by a CCD image sensor, a complex amplitude at each pixel of the CCD plane is obtained using the conventional phase-shifting method. The complex amplitude of a cantilever is reconstructed from the complex amplitude of the CCD plane using the Fresnel diffraction integral. The phase difference distribution on the cantilever before and after deformation, i.e., the out-of-plane displacement distribution, is calculated. In order to decrease the effect of speckle noise, a new method using divided holograms is proposed. The theory and experimental results are shown.

Polarization encoding for an optical security system

Takanori Nomura, Bahram Javidi

Advanced Sciences and Technologies for Security Applications ( Springer )  1   207 - 220   2005年

　概要を見る

A polarization-encoding system for optical security verification is proposed. The polarization information is bonded to an identification card for security verification. As the polarization state cannot be imaged by an ordinary intensity-sensitive device such as a CCD camera, it can provide an additional degree of freedom in using optics to secure information. The expressions for polarization encoded input images are developed using Jones polarization calculus. A nonlinear joint transform correlator is used to provide an optical validation system. Computer simulations and optical experimental results are shown in support of the proposed method.

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Optical image encryption using optimized keys

Takanori Nomura, Bahram Javidi

Advanced Sciences and Technologies for Security Applications ( Springer )  1   193 - 205   2005年

　概要を見る

We have proposed a secure optical data-storage system with a random phase key code based on a configuration of a joint transform correlator. The method to design the key code has been proposed. Computer simulations and optical experiments confirm our proposed system.

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Applications of digital holography for information security

Takanori Nomura, Enrique Tajahuerce, Osamu Matoba, Bahram Javidi

Advanced Sciences and Technologies for Security Applications ( Springer )  1   241 - 269   2005年

　概要を見る

Secure optical storage based on a configuration of a joint transform correlator (JTC) using a photorefractive material is presented. A key code designed by an optimized algorithm so that its Fourier transform has a uniform amplitude distribution and a uniformly random phase distribution is introduced. Original two-dimensional data and the key code are placed side-by-side at the input plane. Both of them are stored in a photorefractive material as a joint power spectrum. The retrieval of the original data can be achieved with the same key code. We can record multiple two-dimensional data in the same crystal by angular multiplexing and/or key-code multiplexing.

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位相シフトディジタルホログラフィ干渉法による変形計測(OS8-2 光学的手法,OS8 実験力学の新たな発展)

森本 吉春, 野村 孝徳, 藤垣 元治, 米山 聡, 高橋 功

材料力学部門講演会講演論文集 ( 一般社団法人日本機械学会 )  2004   571 - 572   2004年

　概要を見る

Measurement of the out-of-plane displacement of a cantilever is performed by phase-shifting digital holographic interferomety. Phase-shifting method is used for the phase analysis of the hologram recorded on a CCD sensor. The complex amplitude of the reconstructed object is obtained from the complex amplitude of the CCD plane using the Fresnel diffraction algorithm. The difference of the phase distributions before and after deformation, i.e. out-of-plane displacement is calculated. In order to decrease the effect of speckle pattern, the hologram is divided into 16 parts. The phase is obtained from the phase with the maximum amplitude among the complex amplitudes obtained from all the separated holograms. As the result, by eliminating the effect of speckle, a smooth phase difference distribution is obtained.

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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.

Real-time analysis of isochromatics and isoclinics using the phase-shifting method

S Yoneyama, Y Morimoto, T Nomura, M Fujigaki, R Matsui

EXPERIMENTAL MECHANICS ( SPRINGER )  43 ( 1 ) 83 - 89   2003年03月  [査読有り]

　概要を見る

This paper studies a new real-time phase-shifting method for the analysis of isochromatic and isoclinic parameters in photoelasticity. By rotating an analyzer at a constant rate and an output quarter-wave plate at a double rate of the analyzer and recording images by a CCD camera continuously, sequential images which brightness is integrated by sensors in a CCD camera during phase-shifting are obtained. Then, the distributions of the isochromatic and isoclinic parameters are obtained immediately and quantitatively using the proposed phase-shifting algorithm. The proposed method can be applied to high-speed inspection of optical elements or glass products. Also, it is expected that slowly varying time-dependent problems can be analyzed by the proposed method.

Secure optical data storage with random phase key codes by use of a configuration of a joint transform correlator

T Nomura, S Mikan, Y Morimoto, B Javidi

APPLIED OPTICS ( OPTICAL SOC AMER )  42 ( 8 ) 1508 - 1514   2003年03月  [査読有り]

　概要を見る

A secure optical storage based on a configuration of a joint transform correlator by use of a photorefractive material is presented. A key code designed through the use of an optimized algorithm so that its Fourier transform has a uniform amplitude distribution and a uniformly random phase distribution is introduced. Original two-dimensional data and the key code are placed side-by-side at the input plane. Both of them are stored in a photorefractive material as a joint power spectrum. The retrieval of the original data can be achieved with the same key code. We can record multiple two-dimensional data in the same crystal by angular multiplexing and/or key code multiplexing. (C) 2003 Optical Society of America.

535 位相シフトデジタルホログラフィによるたわみ分布計測

高橋 功, 森本 吉春, 野村 孝徳, 米山 聡, 藤垣 元治

年次大会講演論文集 ( 一般社団法人日本機械学会 )  2002   175 - 176   2002年

　概要を見る

In this study, the deflection distribution of a cantilever is measured combining the holographic interferometry and phase-shifting digital holography. Holographic interferometry can measure with high accuracy, high sensitivity, and full-field by noncontacting. But the development processing of a film is troublesome by holographic interferometry. Digital holography record on CCD and it reconstructs it with a computer. Therefore, development processing is not needed and it is early reproducible by digital holography. Digital holography has the amplitudes information and phase information in digital information. By the holographic interferometer, the sum of complex amplitude before and after deformation is reconstructed. In this study, the sum of complex amplitude before and after deformation is calculated and reconstructed. Therefore, phase difference computed for digital information and the displacement of a nano-meter order will be able to measure with this method.

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219 位相シフト法を用いた光弾性皮膜法による実時間応力・ひずみ解析(OS6-5 光弾性法II)(OS6 実験力学の新展開)

加藤 良二, 松井 亮, 森本 吉春, 野村 孝徳, 藤垣 元治, 米山 聡

材料力学部門講演会講演論文集 ( 一般社団法人日本機械学会 )  2001   153 - 154   2001年

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