The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Takanori Nomura - One of the best experts on this subject based on the ideXlab platform.

  • correlation based multiplexing of Complex Amplitude data pages in a holographic storage system using digital holographic techniques
    Polymers, 2017
    Co-Authors: Teruyoshi Nobukawa, Takanori Nomura
    Abstract:

    Holographic recording media can store the Amplitude and the phase, or the Complex Amplitude, of a beam on the basis of holography. Owing to this characteristic, digital data can be encoded onto the Complex Amplitude of a signal beam in holographic data storage. However, most of conventional holographic storage systems encode digital data onto the Amplitude alone because there are difficulties for modulating and detecting the phase. To solve the difficulties, a holographic storage system using digital holographic techniques has been proposed. With the help of digital holographic techniques, it is possible to modulate and detect the Complex Amplitude of a signal beam. Moreover, the proposed system can modulate the Complex Amplitude of a reference beam. In this paper, by making use of the capability, a correlation-based multiplexing with uncorrelated reference beams is demonstrated in the proposed system. Multiple holograms can be recorded in the same volume of a recording medium with no need for mechanical movements. Experimental results show that the proposed system with a correlation-based multiplexing can improve the storage capacity and can utilize the full potential of a recording medium without crosstalk noise stem from the optical setup.

  • multilevel recording of Complex Amplitude data pages in a holographic data storage system using digital holography
    Optics Express, 2016
    Co-Authors: Teruyoshi Nobukawa, Takanori Nomura
    Abstract:

    A holographic data storage system using digital holography is proposed to record and retrieve multilevel Complex Amplitude data pages. Digital holographic techniques are capable of modulating and detecting Complex Amplitude distribution using current electronic devices. These techniques allow the development of a simple, compact, and stable holographic storage system that mainly consists of a single phase-only spatial light modulator and an image sensor. As a proof-of-principle experiment, Complex Amplitude data pages with binary Amplitude and four-level phase are recorded and retrieved. Experimental results show the feasibility of the proposed holographic data storage system.

  • single exposure phase shifting digital holography using a random Complex Amplitude encoded reference wave
    Applied Optics, 2013
    Co-Authors: Masatoshi Imbe, Takanori Nomura
    Abstract:

    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.

  • single exposure phase shifting digital holography using a random phase reference wave
    Optics Letters, 2010
    Co-Authors: Takanori Nomura, Masatoshi Imbe
    Abstract:

    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.

Toyohiko Yatagai - One of the best experts on this subject based on the ideXlab platform.

  • experimental verification of multilevel spatial pattern generation from binary data page with four step phase pattern conference presentation
    Proceedings of SPIE, 2016
    Co-Authors: Daisuke Barada, Toyohiko Yatagai
    Abstract:

    Holographic memory is expected for cold storage because of the features of huge data capacity, high data transfer rate, and long life time. In holographic memory, a signal beam is modulated by a spatial light modulator according to data pages. The recording density is dependent on information amount per pixel in a data page. However, a binary spatial light modulator is used to realize high data transfer rate in general. In our previous study, an optical conversion method from binary data to multilevel data has been proposed. In this paper, the principle of the method is experimentally verified. In the proposed method, a data page consists of symbols with 2x2 pixels and a four-step phase mask is used. Then, the Complex Amplitudes of four pixels in a symbol become positive real, positive imaginary, negative real, and negative imaginary values, respectively. A square pixel pattern is spread by spatial frequency filtering with a square aperture in a Fourier plane. When the aperture size is too small, the Complex Amplitude of four pixels in a symbol is superposed and a symbol is regarded as a pixel with a Complex number. In this work, a data page pattern with a four-step phase pattern was generated by using a computer-generated circular polarization hologram (CGCPH). The CGCPH was prepared by electron beam lithography. The page data pattern is Fourier transformed by a lens and spatially filtered by a variable rectangular aperture. The Complex Amplitude of the spatial filtered data page pattern was measured by digital holography and the principle was experimentally verified.

  • Dual-channel polarization holography: a technique for recording two Complex Amplitude components of a vector wave
    Optics letters, 2012
    Co-Authors: Daisuke Barada, Takanori Ochiai, Takashi Fukuda, Shigeo Kawata, Kazuo Kuroda, Toyohiko Yatagai
    Abstract:

    In this Letter, the principle of polarization holography for recording an arbitrary vector wave on a thin polarization-sensitive recording medium is proposed. It is analytically shown that the Complex Amplitudes of p- and s-polarization components are simultaneously recorded and independently reconstructed by using an s-polarized reference beam. The characteristics are experimentally verified.

  • doppler phase shifting digital holography and its application to surface shape measurement
    Optics Letters, 2010
    Co-Authors: Yuichi Kikuchi, Daisuke Barada, Tomohiro Kiire, Toyohiko Yatagai
    Abstract:

    Digital holography utilizing the optical Doppler effect is proposed in which the time variation of interference fringes is recorded using a high-speed CMOS camera. The Complex Amplitude diffracted from the object wave is extracted by time-domain Fourier transforming the recorded interference fringes. The method was used to measure the surface shape of a concave mirror under a disturbed environment.

Masatoshi Imbe - One of the best experts on this subject based on the ideXlab platform.

Tong Zhang - One of the best experts on this subject based on the ideXlab platform.

  • three dimensional microscopy with phase shifting digital holography
    Optics Letters, 1998
    Co-Authors: Tong Zhang, Ichirou Yamaguchi
    Abstract:

    We applied phase-shifting digital holography to microscopy by deriving the Complex Amplitude of light scattered from microscopic three-dimensional objects through a microscope objective by video camera recording, phase-shifting analysis, and computer reconstruction. This method requires no mechanical movement and provides a flexible display and quantitative evaluation of the reconstructed images. A theory of image formation and experimental verification with specimens are described.

  • phase shifting digital holography
    Optics Letters, 1997
    Co-Authors: Ichirou Yamaguchi, Tong Zhang
    Abstract:

    A new method for three-dimensional image formation is proposed in which the distribution of Complex Amplitude at a plane is measured by phase-shifting interferometry and then Fresnel transformed by a digital computer. The method can reconstruct an arbitrary cross section of a three-dimensional object with higher image quality and a wider viewing angle than from conventional digital holography using an off-axis configuration. Basic principles and experimental verification are described.

Ichirou Yamaguchi - One of the best experts on this subject based on the ideXlab platform.

  • three dimensional microscopy with phase shifting digital holography
    Optics Letters, 1998
    Co-Authors: Tong Zhang, Ichirou Yamaguchi
    Abstract:

    We applied phase-shifting digital holography to microscopy by deriving the Complex Amplitude of light scattered from microscopic three-dimensional objects through a microscope objective by video camera recording, phase-shifting analysis, and computer reconstruction. This method requires no mechanical movement and provides a flexible display and quantitative evaluation of the reconstructed images. A theory of image formation and experimental verification with specimens are described.

  • phase shifting digital holography
    Optics Letters, 1997
    Co-Authors: Ichirou Yamaguchi, Tong Zhang
    Abstract:

    A new method for three-dimensional image formation is proposed in which the distribution of Complex Amplitude at a plane is measured by phase-shifting interferometry and then Fresnel transformed by a digital computer. The method can reconstruct an arbitrary cross section of a three-dimensional object with higher image quality and a wider viewing angle than from conventional digital holography using an off-axis configuration. Basic principles and experimental verification are described.