Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/26—Processes or apparatus specially adapted to produce multiple sub- holograms or to obtain images from them, e.g. multicolour technique
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/26—Processes or apparatus specially adapted to produce multiple sub- holograms or to obtain images from them, e.g. multicolour technique
  • G03H1/2645—Multiplexing processes, e.g. aperture, shift, or wavefront multiplexing
  • G03H1/265—Angle multiplexing; Multichannel holograms
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
  • G11B7/0065—Recording, reproducing or erasing by using optical interference patterns, e.g. holograms

Definitions

• Holographic recording method holographic recording device, holographic recording / reproducing method, holographic recording / reproducing device, and holographic recording medium
• the present invention relates to a holographic recording method, a holographic recording device, a holographic recording / reproducing method, a holographic recording / reproducing device, and a holographic recording medium.
• one of a signal light 4 and a reference light 6 obtained by branching a laser light source is applied to a predetermined layer in a recording layer 2 A of a holographic recording medium 2.
• a holographic recording method has been proposed in which information is angle-multiplex-recorded as a hologram by intersecting the other at an incident angle ⁇ and changing the incident angle ⁇ at a predetermined angle pitch ⁇ ((for example, 2003-178460 .;).
• thicker the recording layer 2A of the holographic recording medium 2 the narrower the range of the incident angle satisfying the Bragg condition, and the better the angle selectivity.
• the relationship between the incident angle of the reference light 6 and the diffraction efficiency, that is, the angle selectivity differs depending on the thickness of the recording layer 2A.
• the medium with a thick recording layer 2A shown in FIG. 11 (A) has a smaller incident angle of the reference beam 6 that satisfies the Bragg condition than the medium with a thin recording layer 2A shown in FIG. 11 (B). The range becomes narrower and the angle selectivity increases.
• the present invention has been made to solve such a problem, and a holographic recording method and a holographic recording method capable of ensuring reproduction compatibility between media having different angle selectivities. It is an object to provide an apparatus, a holographic recording / reproducing method, a holographic recording / reproducing apparatus, and a holographic recording medium.
• a holographic recording method As a result of earnest research, the inventor of the present invention has found that a holographic recording method, a holographic recording apparatus, a holographic recording / reproducing method, and a holographic recording method capable of ensuring reproduction compatibility between media having different angle selectivities.
• a graphic recording / reproducing device and a holographic recording medium were found.
• One of the signal light and the reference light branched from the laser light source intersects the other at a predetermined incident angle on the recording layer, and changes the incident angle at a predetermined angular pitch.
• a holographic recording method in which information is angle-multiplexed and recorded as a hologram in a first format or a second format having a higher angle selectivity, wherein the information has a higher angle selectivity and information is recorded in a second format.
• a holographic recording method characterized in that, at the time of recording, the incident angle can be adjusted so as to include an incident angle that satisfies the Bragg condition when recording in the first format.
• the angular pitch force at the time of recording in the second format is The holographic recording method according to the above (1), characterized in that the holographic recording method includes an angular pitch that is about several times smaller than the angular pitch.
• the control information on the angle selectivity which includes at least information on the incident angle and the wavelength of the reproduction light, is recorded at an incident angle common to the second format and the first format.
• One of the signal light and the reference light obtained by branching the laser light source intersects the other at a predetermined incident angle on the recording layer, and changes the incident angle at a predetermined angle pitch.
• a holographic recording device capable of performing angle multiplex recording of information as a hologram in a first format or a second format having a higher angle selectivity, wherein the information is stored in the second format having a higher angle selectivity.
• a signal optical system and a reference optical system that can adjust the incident angle to include an incident angle that satisfies the Bragg condition when recording in the first format.
• the angle pitch at the time of recording in the first format is ⁇
• the angle pitch at the time of recording in the second format is ⁇ Zn (n is 2 or more).
• the angular pitch force at the time of recording in the second format is The holographic recording device according to the above (7), wherein the holographic recording device includes an angle pitch that is about several times smaller than the angle pitch.
• a control information force related to the angle selectivity which comprises at least information on an incident angle and a wavelength of the reproduction light, an incident angle common to the second format and the first format.
• the holographic recording apparatus according to any one of (7) to (11), wherein the holographic recording apparatus is capable of recording.
• a holographic recording / reproducing method wherein when recording information in the second format having a high angle selectivity, the incident angle includes an incident angle satisfying a Bragg condition when recording in the first format.
• Control information on the angular selectivity which is at least adjustable and includes at least information on the incident angle and the wavelength of the reproduction light, in the second format and the first format.
• a holographic recording / reproducing method comprising: a step of recording at a common angle of incidence on a mat, and a step of acquiring the control information before reproducing information other than the control information. Law.
• Information can be angularly multiplex-recorded as a holo-drum by the second format having higher angle selectivity, and the recorded information can be reproduced by irradiating reproduction light composed of one of the signal light and the reference light.
• a holographic recording / reproducing apparatus wherein when recording information in the second format having a high angle selectivity, the incident angle includes an incident angle that satisfies a Bragg condition when recording in the first format. The control information on the angle selectivity is adjusted in the second format and the first format.
• the control information regarding the angle selectivity which includes at least information on the incident angle and the wavelength of the reproduction light, is recorded at an incident angle common to the second format and the first format.
• the holo drama recording medium according to any one of the above (17) to (21).
• FIG. 1 is an optical system diagram of a holographic recording device according to a first embodiment of the present invention.
• FIG. 2 is a side view schematically showing a relationship between a recording layer, a reference beam, and a signal beam in the holographic recording device.
• FIG. 3 is a graph showing angle selectivity of a lower format medium according to Embodiment 1 of the present invention.
• FIG. 4 is a graph showing the angular selectivity of the upper format medium and the lower format medium according to the first embodiment of the present invention.
• FIG. 5 is a schematic diagram showing a state of angle multiplex recording of the holographic recording device according to the first embodiment of the present invention.
• FIG. 7 is a graph for explaining another recording method by the holographic recording device according to the first embodiment of the present invention.
• FIG. 8 is a graph for explaining still another recording method by the holographic recording device according to the first embodiment of the present invention.
• FIG. 9 is an optical system diagram of a holographic recording / reproducing apparatus according to Embodiment 2 of the present invention.
• FIG. 10 is a side view schematically showing a relationship between a recording layer, a reference beam, and a signal beam in a conventional holographic recording device.
• FIG. 11 is a graph showing the angle selectivity of a holographic recording medium having different recording layer thicknesses.
• one of the signal light and the reference light branched from the laser light source intersects the other at a predetermined incident angle in the recording layer, and the incident angle is changed at a predetermined angular pitch.
• a holographic recording method in which information is angularly multiplexed and recorded as a hologram in a first format or a second format having higher angle selectivity, wherein information is recorded in the second format having higher angle selectivity.
• the above-mentioned problem has been solved by making it possible to adjust the incident angle to include an incident angle that satisfies the Bragg condition when recording in the first format.
• the "format" according to the present invention means both a physical format that specifies the recording capacity of a recording medium, a modulation method, an error correction coding method, and the like, and a logical format that specifies a recording and reproduction method.
• a DV D-Video format, a DVD-Audio format, etc. in a DVD correspond to this.
• first format and the “second format” according to the present invention are different from each other only in the angle selectivity and mean the same in other physical format and logical format.
• the first format having the lower angle selectivity is expressed as “lower format”
• the second format having the higher angle selectivity is expressed as “higher format”.
• the holographic recording device 10 transmits a laser light source 12 and one of the linearly polarized light of the laser light from the laser light source 12, for example, a p-polarized component whose vibration plane is orthogonal, and an s-polarized component.
• a polarization beam splitter 14 that reflects the light
• a signal optical system 18 that guides the s-polarized signal light reflected by the polarization beam splitter 14 to the holographic recording medium 16, and a p-polarized light that passes through the polarization beam splitter 14
• a reference optical system 20 whose polarization plane is rotated by about 90 degrees by the 1Z2 wavelength plate 15 and guides the reference light polarized in the s-polarized state to the holographic recording medium 16.
• the signal optical system 18 includes a beam extractor composed of two first and second lenses 18A and 18B and a pinhole 18C in order to enlarge the beam diameter of the signal light emitted from the laser light source 12.
• a Fourier lens 18G for condensing the signal light into the holographic recording medium 16.
• the beam expander 18D forms a relay optical system by arranging the first and second lenses 18A and 18B at a distance substantially equal to the sum of the respective focal lengths.
• the pinhole 18C is located near the confocal point of the system, and functions as a spatial filter.
• the reference optical system 20 includes two rotating mirrors 20 A and 20 B that reflect the reference light, which has also entered the polarizing beam splitter 14, in the direction of the holographic recording medium 16.
• the rotation mirrors 20A and 20B are supported by the rotation stages 20C and 20D so that the reflection angle can be adjusted.
• the angle of incidence on the recording medium 16 can be modulated. That is, angle multiplex recording is enabled.
• the signal light that has entered the signal optical system 18 has its beam diameter expanded by a beam expander 18D, is reflected by a mirror 18E, is given data in the form of intensity modulation by an SLM 18F, and The light is condensed by the lens 18G and subjected to the Fourier transform of the intensity distribution, and is applied to the holographic recording medium 16.
• the reference light that has entered the reference optical system 20 is reflected at a predetermined angle by the two rotating mirrors 20A and 20B, and then crosses with the irradiated signal light in the holographic recording medium 16. I do.
• the signal light and the reference light cause optical interference in a region where the signal light and the reference light intersect, and this is recorded on the holographic recording medium 16 as a diffraction grating.
• a plurality of pieces of information are angularly multiplex-recorded on the holographic recording medium 16 through a process as described below.
• a signal light is applied from a direction perpendicular to the surface of the holographic recording medium 16 and a reference light is applied to the signal light from an angle ⁇ .
• both interference fringes are formed, and both interference fringes are formed.
• Angle multiplex recording is performed on the recording layer 16A of the physical recording medium 16.
• the angle pitch ⁇ ⁇ is set to be larger than the range of the incident angle at which the hologram can be reproduced (satisfies the Bragg condition) so that no crosstalk occurs between the information (holograms). Being done.
• the lower format holographic recording medium (hereinafter, simply referred to as “lower format medium”) LM As shown in Fig. 3, the incident angle of the reference light is 0
• FIG. 5 When recording information on the holographic recording medium UM (hereinafter simply referred to as "upper format medium") of higher format having higher angle selectivity than the lower format medium LM, FIG. As shown in Fig. 5, the incident angle of the reference beam is adjusted to include the incident angles 0, 0, 0 that satisfy the Bragg condition during recording in the lower format.
• the angle pitch of the incident angle at the time of recording on the lower format medium LM is ⁇ 0.
• the angle pitch ⁇ 0 during recording of the upper format medium UM is ⁇ 0 /
• the angle pitch ⁇ at the time of recording the upper format medium UM is used.
• ⁇ is set to 1Z3 of the angle pitch ⁇ 0 when recording on the lower format medium LM.
• the present invention is not limited to this. If the angle pitch at the time of recording in the lower format is ⁇ , the angle pitch at the time of recording in the upper format is ⁇ ⁇ Zn (n is 2 It is preferable to set to (the above integer).
• the format information (control information) relating to the angle selectivity, including the information on the incident angle and the wavelength of the reproduction light, is stored in the upper format media UM and UM.
• the incident angle is changed to the low format (second format).
• (1 format) the incident angles 0, 0, 0 that satisfy the Bragg condition
• the angle pitch at the time of recording in the lower format is ⁇
• the angle pitch at the time of recording in the upper format is set to ⁇ Zn (n is an integer of 2 or more). Therefore, when recording the lower format medium LM with a (higher) holographic recording device capable of reproducing the upper format medium UM, the incident angle can be easily controlled.
• the format information (control information) relating to the angle selectivity which includes at least the information on the incident angle and the wavelength of the reproduction light, is shared by the upper format medium UM and the lower format medium LM. , 0
• control information between the mat medium UM and the lower format medium LM can be ensured, and control during reproduction can be facilitated by information such as the incident angle and wavelength of the reproduction light.
• the holographic recording method according to the present invention is not limited to the holographic recording method according to the first embodiment.
• the angle pitch includes 3 ⁇ 0 or ⁇ 0.
• the divisor 3 ⁇ 0X (tA) It is preferable that the number is 3 ⁇ .
• the angular pitch at the time of recording in the upper format is set to include an angular pitch which is approximately several powers of each angular pitch in the lower format.
• the divisor is the greatest common divisor, the angle pitch can be increased and the incident angle can be correspondingly increased. Control becomes easy.
• the holographic recording / reproducing device 30 according to the second embodiment is obtained by adding the detection optical system 22 to the holographic recording device 10 according to the first embodiment.
• the detection optical system 22 includes an imaging element 22A and an imaging lens 22B for detecting diffracted light generated when the holographic recording medium 16 is irradiated with reference light, and a signal light transmitted to the holographic recording medium 16. And an address information detector 22C for detecting angle-multiplexed diffracted light generated when the light is irradiated.
• the address information detector 22C can be constituted by, for example, a CCD camera or the like.
• the optical path of the signal optical system 18 is cut off and the holographic recording medium 16 is irradiated with only the reference light.
• the reference light is irradiated under the incident angle condition corresponding to the hologram to be reproduced, the signal light is emitted as the diffracted light. Therefore, by detecting the emitted signal light with the imaging device 22A via the imaging lens 22B, the target information can be reproduced.
• the holographic recording medium 16 is irradiated only with the signal light by interrupting the optical path of the reference optical system 20, all the angle-multiplexed reference lights are simultaneously emitted as diffracted light. Therefore, by detecting the emitted reference light by the address information detector 22C, it is possible to simultaneously reproduce the target information angle-multiplex-recorded.
• such reproduction of the angle-multiplexed reference light is referred to as “associative reproduction”. According to this "associative reproduction”, it is possible to realize an ultra-high-speed search function for instantly searching for specific data.
• the format information recorded on the holographic recording medium 16 is obtained by the associative reproduction.
• the holographic recording medium 16 When the holographic recording medium 16 is set in the holographic recording / reproducing device 30 to be in a reproducible state, first, associative reproduction is performed to determine the incident angle and wavelength of the reproduction light. The format information in which the information is recorded is obtained. Based on this format information, reproduction control is performed, and information other than the format information is sequentially reproduced.
• the incident angle is changed to the lower format (first format).
• the format information (control information) related to angle selectivity which can be adjusted to include the incident angle that satisfies the Bragg condition during recording in the (format), and includes at least information on the incident angle and wavelength of the reproduction light.
• control information since the format information (control information) is obtained by the associative reproduction, the control information can be obtained quickly, and the time until the start of the reproduction can be greatly reduced.
• the holographic recording device and the holographic recording / reproducing device according to the present invention are not limited to the structure of the holographic recording device 10 and the holographic recording / reproducing device 30 according to the first and second embodiments. Absent.
• the incident angle of the reference light is changed by a predetermined angle pitch, and angle multiplex recording is performed on the recording layer of the holographic recording medium. Good.
• the reproduction compatibility between media having different angle selectivities Can be secured.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optical Recording Or Reproduction (AREA)
• Holo Graphy (AREA)

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• 2004
  • 2004-04-15 JP JP2004120633A patent/JP4355607B2/ja not_active Expired - Fee Related
• 2005
  • 2005-03-29 WO PCT/JP2005/005932 patent/WO2005101137A1/ja not_active Ceased
  • 2005-03-29 US US11/547,682 patent/US7869106B2/en not_active Expired - Fee Related

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