JP2005172956A - Holographic memory reconstruction method, its system and holographic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for simultaneously reading out the holograms recorded in a plurality of recording regions in a holographic recording medium. <P>SOLUTION: The holograms are respectively recorded in multiplicity in the plurality of the recording regions 13A to 13H in a recording layer 13 of the holographic recording medium 12 and the respective recording regions 13A to 13H are irradiated with a reconstruction light beam R from a reconstruction light source 14 as a plurality of divided beams Ra to Rh by a beam divider 16. The diffracted light rays generated in the respective recording regions 13A to 13H are received in block by a photodetector 18. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a holographic memory reproducing method for reproducing information from a holographic recording medium on which a hologram is formed, an apparatus therefor, and a holographic recording medium suitable for use in the holographic memory reproducing method.

  In holographic recording, interference fringes generated by causing two light beams (object light and reference light) to interfere with each other in the recording layer of the holographic recording medium are recorded as holograms. By changing, it becomes possible to record many different interference fringes in the same area in the recording layer, and this is called multiplexing.

  As multiplexing methods, angle multiplexing, shift multiplexing, wavelength multiplexing, phase code multiplexing, etc. have been proposed. When reading information recorded as a hologram, a light beam equivalent to one of the light beams used for recording is reproduced. The recorded information is read by irradiating the recording layer as a light beam and detecting the generated diffracted light.

  In this case, the reproduction light beam is irradiated to one portion of the recording area in the recording layer and the recorded information is read. In this case, the recording medium is made relatively to the reproduction light beam in accordance with the multiplexing method. They are moved or the incident angle of the reproduction light beam is modulated.

  In any of the above cases, the recording area irradiated with the reproduction light beam needs to be moved to the next recording area by mechanical movement or rotation, movement of the optical system, or the like.

  As described above, a drive motor or the like for moving the holographic recording medium or the optical system is required to sequentially shift the recording area irradiated with the reproduction light beam and read the information recorded in the plurality of recording areas. Therefore, the entire system becomes large, and movement by mechanical means has a problem that access and transfer speed of information are limited, and high-speed access and high-speed transfer become difficult.

  The present invention has been made in view of the above problems, and a holographic memory reproducing method capable of high-speed access to a plurality of recording areas and high-speed transfer without using mechanical means, An object of the present invention is to provide an apparatus and a holographic recording medium.

  As a result of diligent research, the inventor of the present invention divided the reproduction light beam into a plurality of beams and irradiates a plurality of recording areas at the same time, thereby reading information from the plurality of recording areas at a time, It has been found that high-speed access and high-speed transfer can be performed without using a special means.

  That is, the following object can be achieved by the present invention described below.

  (1) Holography for reproducing information from the hologram by irradiating a reproduction light beam to a holographic recording medium having a plurality of recording areas in the surface direction of the recording layer and forming a hologram for each recording area A memory reproduction method in which a reproduction light beam emitted from a light source is divided into a plurality of divided beams, the same number of the recording areas are simultaneously irradiated, and diffracted light from the plurality of recording areas is simultaneously received to collectively collect information. A holographic memory reproducing method, wherein the holographic memory is read.

  (2) The holographic memory reproducing method according to (1), wherein a hologram is phase-code multiplexed recorded in the recording area, and the recording phase code is superimposed on the reproducing light beam.

  (3) A reproduction light source that emits a reproduction light beam, a beam division device that guides the reproduction light beam as a plurality of divided beams so as to irradiate recording areas at different positions in the surface direction of the holographic recording medium, and the division A holographic memory reproducing device comprising: at least one light receiver for reading out diffracted light generated from a hologram recorded in the recording area by irradiation of a beam.

  (4) The holographic method according to (3), wherein a phase code modulator for phase-modulating the reproduction light beam is provided on an optical path of the reproduction light beam between the reproduction light source and a beam splitter. Memory playback device.

  (5) A holographic recording medium in which a hologram is formed in a recording layer corresponding to interference fringes caused by irradiation of object light and reference light, and each hologram is phase code multiplexed in a plurality of recording regions of the recording layer. A holographic recording medium in which holograms having the same phase code are recorded and arranged one by one in each recording area.

  In the present invention, the reproduction light beam is divided into a plurality of divided beams, which are simultaneously irradiated onto the recording area of the holographic recording medium, and the diffracted light from the plurality of recording areas is simultaneously received to read the information in a batch. It has the effect of being able to.

  For a holographic recording medium having a plurality of recording areas in the surface direction of the recording layer and having a hologram formed for each recording area, the same number of recordings is performed with the reproduction light beam emitted from the light source as a plurality of divided beams. The above object is achieved by simultaneously irradiating the area and simultaneously and separately receiving the diffracted light from the plurality of recording areas and reading out the information collectively.

  Next, with reference to FIG. 1, a holographic memory reproducing apparatus 10 according to the first embodiment of the present invention will be described.

  The holographic memory reproducing device 10 has a plurality of recording areas 13A to 13H in the surface direction of the recording layer 13, and is recorded on a holographic recording medium 12 in which a hologram is formed for each of the recording areas 13A to 13H. It is for playing back information.

  The holographic memory reproducing apparatus 10 includes a reproducing light source 14 that is a laser light source that emits a reproducing light beam, and recording areas 13A to 13A in the holographic recording medium 12 by using the reproducing light beam R as a plurality of divided beams Ra to Rh. The beam splitting device 16 guides the laser beam to irradiate 13H, and the light receiver 18 for reading out the diffracted light generated from the recording regions 13A to 13H by the irradiation of the split beams Ra to Rh.

  The beam splitting device 16 splits one incident light beam into a plurality of light beams, and is composed of, for example, a diffractor or a polyhedron.

  Collimating lenses 20A to 20H are arranged on the optical path of the diffracted light from the recording areas 13A to 13H to the light receiver 18, respectively. Further, a phase spatial light modulator 22 as a phase code modulator is provided on the optical path of the reproduction light beam R between the reproduction light source 14 and the beam splitter 16. Reference numeral 15 in FIG. 1 indicates a stop for making the divergent light beam from the reproduction light source 14 a parallel light beam.

  In the recording areas 13A to 13H of the holographic recording medium 12, the object light irradiated when information is recorded is amplitude-modulated by a spatial light modulator (not shown) according to the information to be recorded. The reference light is phase-modulated by a phase spatial light modulator (not shown) similar to the phase spatial light modulator 22, and information is recorded as a hologram.

  Further, the holograms in the recording areas 13A to 13H are phase code multiplex-recorded, and one hologram of the same phase code is arranged in each recording area.

  Next, a process of reproducing information from the hologram recorded in the recording areas 13A to 13H of the holographic recording medium 12 by the holographic memory reproducing apparatus 10 will be described.

  The laser light emitted from the reproduction light source 14 which is a laser light source is incident on the phase spatial light modulator 22 as a reproduction light beam R and is phase code modulated here.

  The reproduction light beam R subjected to the phase code modulation is split by the beam splitting device 16 into split beams Ra to Rh irradiated on the recording areas 13A to 13H, respectively.

  Since the split beams Ra to Rh are respectively modulated with the same phase code, the diffracted light with the highest diffraction efficiency is obtained from the hologram with the phase code that coincides among the holograms multiplexed and recorded in the recording regions 13A to 13H. Occur.

  The diffracted light is simultaneously received by the light receiver 18, and information on amplitude modulation imparted to the object light at the time of recording is reproduced from the diffracted light to read the information.

  That is, information recorded in the plurality of recording areas 13A to 13H can be read out simultaneously.

  The light receiver 18 receives the plurality of diffracted lights in different regions on the same light receiving surface, but may receive light independently using the same number of light receivers as the diffracted lights.

  In the first embodiment, the phase spatial light modulator 22 is used at the time of reproduction because information is phase-code multiplexed recorded in the recording areas 13A to 13H of the holographic recording medium 12. However, the present invention is not limited to this, and is also applicable to angle multiplex recording.

  That is, as in the holographic memory reproducing device 30 of the second embodiment, the split beams irradiated from the beam splitting device 32 to the holographic recording medium 34 have the same incidence on a plurality of recording areas in the holographic recording medium 34. The holographic recording medium 34 may be irradiated at an angle, and the angle may be synchronously modulated.

  Since the other configuration of the holographic memory reproducing device 30 is the same as that of the first embodiment, the same parts as those of the holographic memory reproducing device 10 are denoted by the same reference numerals and the description thereof is omitted.

1 is an optical system diagram showing a holographic memory reproducing device according to Embodiment 1 of the present invention. Optical system diagram showing holographic memory reproducing apparatus according to the embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 30 ... Holographic memory reproducing device 12, 34 ... Holographic recording medium 13 ... Recording layer 13A-13H ... Recording area 14 ... Reproduction light source 16, 32 ... Beam splitting device 18 ... Light receiver 20A-20H ... Collimating lens 22 ... Phase spatial light modulator R ... Reproduction light beam Ra to Rh ... Split beam

Claims (5)

Holographic memory reproducing method for reproducing information from a hologram by irradiating a reproducing light beam to a holographic recording medium having a plurality of recording areas in the surface direction of the recording layer and forming a hologram for each recording area Because
The reproduction light beam emitted from the light source is divided into a plurality of divided beams, the same number of the recording areas are simultaneously irradiated, the diffracted light from the plurality of recording areas is simultaneously received, and the information is read out collectively. Holographic memory playback method.   2. The holographic memory reproducing method according to claim 1, wherein a hologram is phase-code multiplexed and recorded in the recording area, and the recording phase code is superimposed on the reproducing light beam.   A reproduction light source that emits a reproduction light beam, a beam division device that guides the reproduction light beam as a plurality of divided beams so as to irradiate recording regions at different positions in the surface direction of the holographic recording medium, and irradiation of the divided beams And a holographic memory reproducing apparatus comprising: at least one light receiver for reading out diffracted light generated from the hologram recorded in the recording area. In claim 3,
A holographic memory reproducing device comprising a phase code modulator for phase modulating the reproducing light beam on an optical path of the reproducing light beam between the reproducing light source and the beam splitting device. A holographic recording medium in which a hologram is formed in a recording layer corresponding to interference fringes caused by irradiation of object light and reference light,
Holographic recording medium, wherein holograms are phase-code multiplexed recorded in a plurality of recording areas of the recording layer, and holograms having the same phase code are arranged in units of each recording area .

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