A hologram recording method includes generating a signal beam with data formed by superimposing pattern data, the pattern data representing a pattern in which a large number of plural kinds of pixels having different tone values are arranged in a two-dimensional manner, on an image data of respective pixels represented by tone values corresponding to density, and recording a hologram by irradiating a converted beam formed by Fourier transformation of the generated signal beam with a lens and a reference beam to an optical recording medium.

Hologram recording method and hologram recording apparatus

A hologram recording device for recording interference fringes between reference light and signal light modulated by data displayed in a spatial modulator in a hologram recording material, the hologram recording device including a phase mask for diffusing light, the phase mask being disposed in an optical system that the signal light passes, wherein a minimum unit of a light diffusing pattern formed in the phase mask is a natural number of times a minimum unit of display data of the spatial modulator.

Hologram recording device and phase mask

PROBLEM TO BE SOLVED: To suppress a DC component of signal light without increasing the S/N of a recorded image. SOLUTION: The DC component of the signal light is suppressed by arranging a diffusion plate 12 which diffuses light adjacently to a spatial modulator 11 thereby spreading an intensity distribution of the signal light on a hologram recording material as usual. In addition, it is known by experiment that, when the width of diffusion units of the light such as unevenness of the diffusion plate 12 is made, for example, twice as large as the pixel width of the spatial modulator 11, deterioration in S/N of the recording image due to use of the diffusion plate 12 can be suppressed, and noise caused by the diffusion plate 12 is prevented from being superposed on the signal light to keep the S/N of the recorded image excellent. COPYRIGHT: (C)2006,JPO&NCIPI

Hologram recording device and optical component

There is provided an information recording device for recording the recording information on a recording medium having a recording surface where recording can be performed optically. The information recording device includes a laser light source and a conversion optical system for converting the laser beam emitted from the laser light source into a planar laser beam having an optical flux cross section extending linearly. The information recording device further includes: one-dimensional space modulation means (3) for subjecting the planar laser beam to one-dimensional space modulation according to the recording information; and a recording optical system for applying the planer laser beam subjected to the spatial modulation, as a signal light (Ls) to the recording surface while applying a reference light (Lr) to the recording surface.

Information recording device and information recording/reproducing device

PROBLEM TO BE SOLVED: To make data reproduction impossible in a holographic recording medium without irradiating the medium with high energy erasing beam or physically fracturing the medium. SOLUTION: A holographic recording medium 16 in a holographic recording and reproducing device 10 has a recording layer 17 composed of two divided recording layers 17A, 17B and a crosstalk layer 17C between them. The crosstalk layer 17C has photosensitivity even after multiple recording of data hologram 24 in the recording layer 17 is completed. The layer is irradiated with objective light IOb for erasing of a large beam diameter and with reference light IRe for erasing to produce a crosstalk hologram 26 having low selectivity so that when the data hologram 24 is irradiated with reproducing light, diffracted light is inevitably generated from the crosstalk hologram 26. COPYRIGHT: (C)2005,JPO&NCIPI

Holographic recording medium, method for recording and erasing hologram, and holographic recording and reproducing device

PROBLEM TO BE SOLVED: To obtain an optical recording medium having good Bragg selecting performance while using a laminated structure body by using a technique by which the selecting performance is equal to or less than a specified amount even though the medium thickness of a single active area is changed by equal to or more than the specified amount. SOLUTION: A function for writing and re-constituting many holograms (that is, equal to or more than L/5λ) depends on a fact that the technique having unchanging selecting performance is adopted. L is defined as the thickness of the single active layer, and λis defined as the wavelength of light to be used. The laminated medium has at least two active areas 3, and the areas 3 are separated by inactive areas 1 and 2. The thickness of the areas 3 versus the thickness of the areas 1 and 2 is <=10:1, and desirably <=5:1. Thus, the writing technique used for performing recording uses the laminated medium having the unchanging performance. The decision must be done in the case thickness of an area where a signal beam and a reference beam are superposed each other is equal to or more than the thickness of the medium.

Method for performing recording inside laminated medium

PROBLEM TO BE SOLVED: To realize speedier location and retrieval of holographically stored data by allocating a beam in a limited bandwidth before a holographic element storing a hologram of a reference beam is irradiated with the beam by using a filter like an aperture. SOLUTION: A spatial spectrum of a reference beam is controlled by orienting a beam through a filter 790 for covering a part of a reference beam in order to eliminate high frequency components from the reference beam. The filter 790 controls a plane wave signal 765, and thereby a half value full width of an altered plane wave signal 765' is largely increased. Therefore, the bandwidth of the reference beam is expanded while the peak position is kept as it is. And, to ascertain the position of the prescribed holographic data, a necessary scanning resolution is largely degraded, and the holographic data position can be ascertained more speedily.

Phase correlation multiplexed(pcm) holographic memory system

PROBLEM TO BE SOLVED: To provide an improved optical communication system suitable for use for a short distance, e.g. use for transmission over a distance less than 100 km such as inter-city communications. SOLUTION: The system uses an external cavity laser that consists of a gain medium including an active area, a beam expansion area and an antireflection layer, an optical waveguide that is disposed adjacently to the gain medium, and a Bragg grating that is integrated or coupled with the optical waveguide. The medium and the optical waveguide show a coupling efficiency of at least 40% even in the absence of coupling with an optical system and desirably at least 50% by the beam expansion area, while the laser is designed to operate to emit at least two modes.

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Papers

Method for performing recording inside laminated medium

Phase correlation multiplexed(pcm) holographic memory system

System containing optical semiconuctor waveguide device

ラリー ウィルソン ウィリアム

Papers

Method for performing recording inside laminated medium

Phase correlation multiplexed(pcm) holographic memory system

System containing optical semiconuctor waveguide device

ラリーウィルソンウィリアム