WO2009090905A1 - Dispositif de reproduction d'informations optique, dispositif de tête optique, procédé de reproduction d'informations optique et programme de reproduction d'informations - Google Patents

Dispositif de reproduction d'informations optique, dispositif de tête optique, procédé de reproduction d'informations optique et programme de reproduction d'informations Download PDF

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Publication number
WO2009090905A1
WO2009090905A1 PCT/JP2009/050121 JP2009050121W WO2009090905A1 WO 2009090905 A1 WO2009090905 A1 WO 2009090905A1 JP 2009050121 W JP2009050121 W JP 2009050121W WO 2009090905 A1 WO2009090905 A1 WO 2009090905A1
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WO
WIPO (PCT)
Prior art keywords
optical
light
recording medium
information
layer
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Application number
PCT/JP2009/050121
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English (en)
Japanese (ja)
Inventor
Ryuichi Katayama
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Nec Corporation
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Publication date
Application filed by Nec Corporation filed Critical Nec Corporation
Priority to JP2009550002A priority Critical patent/JP5445141B2/ja
Publication of WO2009090905A1 publication Critical patent/WO2009090905A1/fr

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    • 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
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • 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
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1395—Beam splitters or combiners
    • 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
    • G11B2007/0003—Recording, reproducing or erasing systems characterised by the structure or type of the carrier
    • G11B2007/0009—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage
    • 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

  • the present invention relates to an optical information reproducing apparatus that reproduces information from an optical recording medium, and more particularly, to an optical information reproducing apparatus that reproduces information from an optical recording medium on which information is recorded three-dimensionally.
  • two opposing beams are focused and interfered at the same position in the recording layer of the optical recording medium, and a minute diffraction grating pattern is formed at the focused position.
  • the two beams are condensed at the same position in the recording layer of the optical recording medium.
  • the information is recorded by forming a hologram at the condensing position, and the reference light out of the two beams is collected in the recording layer of the optical recording medium, and the hologram is modulated from the hologram modulated according to the reproduction information.
  • optical information reproducing apparatus for recording a reflection hologram
  • optical information reproducing apparatus described in Non-Patent Document 1.
  • This optical information reproducing apparatus is an optical information reproducing apparatus for bit-type reflection hologram recording, and is a recording / reproducing apparatus for recording and reproducing information on an optical recording medium.
  • FIG. 12 is a conceptual diagram showing a configuration of an optical head device 301 used in the optical information reproducing device described in Non-Patent Document 1.
  • the light emitted from the semiconductor laser 46a is transmitted through the convex lens 47a and converted from the divergent light into parallel light, partly transmitted through the beam splitter 48a, and partly reflected by the beam splitter 48a.
  • the light transmitted through the beam splitter 48a is reflected by the interference filter 49 and condensed in the recording layer of the disk 45 by the objective lens 52a.
  • the light reflected by the beam splitter 48a passes through the shutter 51, a part thereof is reflected by the beam splitter 48b, is reflected by the mirror 50, and is condensed in the recording layer of the disk 45 by the objective lens 52b.
  • the light transmitted through the beam splitter 48a and the light reflected by the beam splitter 48a are condensed and interfered at the same position in the recording layer of the disk 45, and a fine diffraction grating pattern is formed at the condensing position.
  • the light transmitted through the beam splitter 48a is collected in the recording layer of the disk 45, but the light reflected by the beam splitter 48a is blocked by the shutter 51, Do not go to 45.
  • the light condensed in the recording layer of the disk 45 is reflected by the pattern of the diffraction grating formed at the condensing position, passes through the objective lens 52a in the reverse direction, and is reflected by the interference filter 49, and a part thereof is a beam splitter.
  • the light is reflected by 48a and condensed on the light receiving portion of the photodetector 53a by the convex lens 47b.
  • the pattern of the diffraction grating has bit data information.
  • the condensing position of the light transmitted through the beam splitter 48a and the light reflected by the beam splitter 48a is moved in the thickness direction of the recording layer, and the diffraction gratings are formed in multiple layers not only in the in-plane direction of the recording layer but also in the thickness direction.
  • the pattern three-dimensional recording / reproduction can be performed.
  • the convex lens 47c and the photodetector 53b collect the light reflected by the beam splitter 48a with respect to the condensing position of the light transmitted through the beam splitter 48a in the recording layer of the disk 45 when information is recorded on the disk 45. It is used to detect a shift in light position. Further, the semiconductor laser 46 b, the convex lens 47 d, the beam splitter 48 c, the convex lens 47 e, and the photodetector 53 c are used to detect the deviation of the condensing position of the light emitted from the semiconductor laser 46 b with respect to the reference position of the disk 45.
  • Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique for suppressing surface deflection by sandwiching an optical disk between stabilization plates.
  • Patent Document 2 discloses a technique for removing backlight and scattered noise by combining a photodetector having an opening at the center with a normal photodetector.
  • Patent Document 3 discloses a pickup device for a multi-layer optical disc in which first and second focused spots are generated in reflected light separating means, and crosstalk from other layers is removed by a signal from the second focused spot.
  • Patent Document 4 discloses an optical pickup device capable of reading with high resolution by detecting reflected light from a disk further reflected by a micro-aperture mirror with a photodetector.
  • optical head device 301 of FIG. 12 information is reproduced from any one of the plurality of layers of the disk 45 using the light transmitted through the beam splitter 48a.
  • the light transmitted through the beam splitter 48a is positioned between the incident / exit surface of the disk 45 and the selected layer after being incident on the disk 45 and being collected on the selected layer. It is scattered by the pattern of the diffraction grating formed in the layer. Further, the light collected on the selected layer of the disk 45 is reflected by the pattern of the diffraction grating formed at the light collection position and is emitted from the disk 45 until it is emitted from the disk 45. It is scattered by the pattern of the diffraction grating formed in the layer located between the selected layer.
  • the number of layers located between the entrance / exit surface of the disk 45 and the selected layer is large, the amount of scattering received between the incident on the disk 45 and the collection on the selected layer, and The amount of scattering received between the time when the light is reflected by the pattern of the diffraction grating formed at the condensing position and before the light is emitted from the disk 45 increases.
  • the amount of scattering received between the incident on the disk 45 and the light collected on the selected layer is large, the light incident on the disk 45 will not be correctly collected on the selected layer.
  • the amount of scattering received from the time when it is reflected by the pattern of the diffraction grating formed at the condensing position to when it is emitted from the disk 45 it is reflected by the pattern of the diffraction grating formed at the condensing position.
  • the light is not correctly collected on the light receiving portion of the photodetector 53a. For this reason, reproduction cannot be performed with a high signal-to-noise ratio.
  • Patent Documents 1 to 4 described above are combined with the optical head device 301 of FIG. 12, these Patent Documents describe a technique for removing scattered noise from reflected light. Since a technique for reducing scattering itself by the diffraction grating is not described, it is insufficient to solve the above problem.
  • An object of the present invention is to reduce the amount of scattering received before light incident on an optical recording medium on which information is recorded three-dimensionally is reflected by a diffraction grating pattern or hologram and emitted.
  • An optical information reproducing apparatus, an optical head apparatus, an optical information reproducing method, and an information reproducing program capable of performing the above are provided.
  • an optical information reproducing apparatus for reproducing information from an optical recording medium having a plurality of layers on which information is recorded.
  • an optical path switching means capable of switching depending on which layer the data to be reproduced is recorded, and a driving means for driving the optical path switching means.
  • an optical head device for reproducing information from an optical recording medium having a plurality of layers on which information is recorded, and for reproducing data from the optical recording medium.
  • an optical information reproducing method for reproducing information from an optical recording medium having a plurality of layers on which information is recorded.
  • Reproducing beam generating step for generating a reproducing beam irradiated to the optical recording medium to reproduce the data, and a recognition step for recognizing which layer the target data to be reproduced in the optical recording medium is recorded on
  • an irradiation surface determination step for determining which of the first surface and the second surface of the optical recording medium is irradiated based on the recognition result of the recognition step, and the first surface and the second surface.
  • an information reproducing program includes a computer provided in an optical information reproducing apparatus for reproducing information from an optical recording medium having a plurality of layers on which information is recorded.
  • a recognition process for recognizing on which layer the data to be reproduced is recorded, and a reproduction beam is irradiated on either the first surface or the second surface of the optical recording medium based on the recognition result of the recognition process
  • the irradiation surface determination process for determining whether or not to perform is executed.
  • the surface to be irradiated with the reproduction beam is determined depending on which layer the data to be reproduced in the optical recording medium is recorded.
  • a reproduction beam can be irradiated from the surface.
  • FIG. 1 is a conceptual diagram showing a configuration of an optical information reproducing apparatus 100 according to the first embodiment of the present invention.
  • the optical information reproducing apparatus 100 is an optical information reproducing apparatus for recording a bit-type reflection hologram, and is a recording / reproducing apparatus that records and reproduces information with respect to an optical recording medium.
  • the optical information reproducing apparatus 100 drives a spindle 28 on which the disk 2 is mounted and rotated, an optical pickup 101 that records and reproduces information by irradiating the rotating disk 2 with a laser, and the optical pickup 101 and the spindle 28. Circuit (described later in detail).
  • the optical pickup 101 includes an optical head 1a and a positioner 27a on which the optical head 1a is mounted and moved between the inner peripheral side and the outer peripheral side of the disk 2.
  • the positioner 27 a is driven by a positioner driving circuit 43
  • the spindle 28 is driven by a spindle driving circuit 44.
  • the optical head 1a is driven by each of a recording system circuit 102, a reproduction system circuit 103, a shutter driving circuit 36, an objective lens driving circuit 39a, and a relay lens driving circuit 40.
  • the controller 29a controls each of the recording system circuit 102, the reproduction system circuit 103, the shutter drive circuit 36, the objective lens drive circuit 39a, the relay lens drive circuit 40, the positioner drive circuit 43, and the spindle drive circuit 44 described above. The operation of each circuit will be described later.
  • FIG. 2 is a conceptual diagram showing the configuration of the optical head 1a disclosed in FIG.
  • the optical head 1a includes a laser 3 that is a light source for recording and reproducing information to and from the disk 2 and optical components described later.
  • the laser 3 is an external resonator type single mode semiconductor laser using a diffraction grating as an external resonator, and emits light having a wavelength of 405 nm.
  • the light emitted from the laser 3 is transmitted through the expander lens system constituted by the concave lens 4a and the convex lens 5a, the beam diameter is enlarged, and is transmitted from the quarter wavelength plate 6a to be converted from linearly polarized light to circularly polarized light.
  • About 50% is reflected by the polarizing beam splitter 8a as an S-polarized component, and about 50% is transmitted through the polarizing beam splitter 8a as a P-polarized component.
  • the shutter 10a passes the light reflected by the polarizing beam splitter 8a, and the shutter 10b passes the light transmitted through the polarizing beam splitter 8a.
  • the light reflected by the polarization beam splitter 8a passes through the shutter 10a, is reflected by the mirror 9b, passes through the half-wave plate 7a, changes its polarization direction by 90 °, and enters the polarization beam splitter 8b as P-polarized light.
  • the light transmitted through the polarizing beam splitter 8a is reflected by the mirror 9a, passes through the shutter 10b, is reflected by the mirror 9c, enters the polarizing beam splitter 8c as P-polarized light, and transmits almost 100%, and the convex lens 5c and
  • the light is diverged or convergent through the relay lens system constituted by the convex lens 5e, reflected by the mirror 9e, transmitted through the quarter-wave plate 6c, and converted from linearly polarized light to circularly polarized light. 2 is condensed in the recording layer.
  • the light reflected by the polarizing beam splitter 8a and the light transmitted through the polarizing beam splitter 8a are condensed and interfered at the same position in the recording layer of the disk 2, and a pattern of a minute diffraction grating is formed at the condensing position. It is formed.
  • the shutter 10a passes the light reflected by the polarization beam splitter 8a, and the shutter 10b blocks the light transmitted through the polarization beam splitter 8a, or the shutter 10a The light reflected by the splitter 8a is blocked, and the shutter 10b passes the light transmitted through the polarization beam splitter 8a.
  • the shutter 10a passes the light reflected by the polarizing beam splitter 8a and the shutter 10b blocks the light transmitted through the polarizing beam splitter 8a, the light reflected by the polarizing beam splitter 8a is collected in the recording layer of the disk 2. Although it is emitted, the light transmitted through the polarization beam splitter 8a does not travel to the disk 2.
  • the light condensed in the recording layer of the disk 2 is reflected by the pattern of the diffraction grating formed at the condensing position, passes through the objective lens 12a in the reverse direction, passes through the quarter wavelength plate 6b, and is circularly polarized. Is converted to linearly polarized light, reflected by the mirror 9d, passes through the relay lens system constituted by the convex lens 5d and the convex lens 5b in the reverse direction, and enters the polarization beam splitter 8b as S-polarized light, and almost 100% is reflected by the convex lens. The light is condensed on the light receiving portion of the photodetector 13a by 5f.
  • the shutter 10a blocks the light reflected by the polarization beam splitter 8a and the shutter 10b passes the light transmitted through the polarization beam splitter 8a, the light transmitted through the polarization beam splitter 8a enters the recording layer of the disk 2. Although condensed, the light reflected by the polarization beam splitter 8a does not go to the disk 2.
  • the light condensed in the recording layer of the disk 2 is reflected by the pattern of the diffraction grating formed at the condensing position, passes through the objective lens 12b in the reverse direction, passes through the quarter wavelength plate 6c, and is circularly polarized. Is converted to linearly polarized light, reflected by the mirror 9e, passes through the relay lens system constituted by the convex lens 5e and the convex lens 5c in the reverse direction, and enters the polarization beam splitter 8c as S-polarized light, and almost 100% is reflected. The light is condensed on the light receiving portion of the photodetector 13b by 5g.
  • the pattern of the diffraction grating has bit data information.
  • the condensing position of the light reflected by the polarizing beam splitter 8a and the light transmitted through the polarizing beam splitter 8a is moved in the thickness direction of the recording layer, and is diffracted not only in the in-plane direction but also in the thickness direction of the recording layer.
  • By forming a lattice pattern three-dimensional recording / reproduction can be performed.
  • FIG. 3 is a conceptual diagram showing an optical path of an incident beam on the disk 2 when information is recorded on the disk 2 in the optical information reproducing apparatus 100 disclosed in FIGS.
  • the disc 2 has a configuration in which a recording layer 22 is sandwiched between a substrate 21a and a substrate 21b. Glass, plastic, or the like is used as the material for the substrate 21a and the substrate 21b. As the material of the recording layer 22, a photopolymer or the like is used.
  • the incident beam 24a in FIG. 3A and the incident beam 24c in FIG. 3B correspond to the light reflected by the polarization beam splitter 8a in FIG. 2, and the incident beam 24b in FIG.
  • the incident beam 24d corresponds to the light transmitted through the polarizing beam splitter 8a in FIG.
  • the surface of the substrate 21a on the objective lens 12a side and the surface of the substrate 21b on the objective lens 12b side correspond to one surface and the other surface, respectively.
  • the incident beam 24a enters the objective lens 12a as convergent light and is condensed in the recording layer 22, and the incident beam 24b enters the objective lens 12b as divergent light and enters the recording layer 22. Focused.
  • the incident beam 24a and the incident beam 24b are condensed at the same position in the recording layer 22 and interfere with each other, and a minute diffraction grating pattern is formed at the condensed position. At this time, the number of layers from one surface to the layer where the pattern of the diffraction grating is formed is smaller than the number of layers from the other surface to the layer where the pattern of the diffraction grating is formed.
  • the incident beam 24c is incident on the objective lens 12a as diverging light and is condensed in the recording layer 22, and the incident beam 24d is incident on the objective lens 12b as convergent light. It is condensed inside.
  • the incident beam 24c and the incident beam 24d are condensed and interfered at the same position in the recording layer 22, and a minute diffraction grating pattern is formed at the condensed position.
  • the number of layers from one surface to the layer where the pattern of the diffraction grating is formed is larger than the number of layers from the other surface to the layer where the pattern of the diffraction grating is formed.
  • FIG. 4 is a conceptual diagram showing optical paths of an incident beam to the disk 2 and a reflected beam from the disk 2 when reproducing information from the disk 2 in the optical information reproducing apparatus 100 disclosed in FIGS. .
  • the incident beam 25a in FIG. 4A corresponds to the light reflected by the polarization beam splitter 8a in FIG. 2, and the incident beam 25b in FIG. 4B corresponds to the light transmitted through the polarization beam splitter 8a in FIG. .
  • the incident beam 25a is incident on the objective lens 12a as convergent light and is condensed in the recording layer 22.
  • This light is reflected by the pattern of the diffraction grating 23b formed at the condensing position to become a reflected beam 26a, and is emitted from the objective lens 12a as divergent light.
  • the reflected beam 26a is received by the photodetector 13a in FIG. At this time, the number of layers from one surface to the layer where the pattern of the diffraction grating is formed is smaller than the number of layers from the other surface to the layer where the pattern of the diffraction grating is formed.
  • the incident beam 25b enters the objective lens 12b as convergent light and is condensed in the recording layer 22.
  • This light is reflected by the pattern of the diffraction grating 23e formed at the condensing position to become a reflected beam 26b, and is emitted from the objective lens 12b as divergent light.
  • the reflected beam 26b is received by the photodetector 13b in FIG.
  • the number of layers from one surface to the layer where the pattern of the diffraction grating is formed is larger than the number of layers from the other surface to the layer where the pattern of the diffraction grating is formed.
  • diffraction grating patterns are formed in six layers in the thickness direction of the recording layer 22, and these layers are sequentially formed from the side closer to one surface toward the side closer to the other surface. These will be referred to as the first to sixth layers.
  • the patterns of the diffraction gratings 23a to 23f are formed in the first to sixth layers, respectively.
  • information is reproduced from a selected one of the first to third layers using the incident beam 25a, and the fourth to sixth layers are used using the incident beam 25b. Play information from the selected layer.
  • the number of layers from one surface to the selected layer is 1 to 3
  • the number of layers from the other surface to the selected layer is 4 to 6, and the former is Less than the latter.
  • the number of layers positioned between one surface and the selected layer is small.
  • the amount of scattering received before exiting from the disk 2 is reduced.
  • the incident beam 25a is incident on the disk 2 until it is condensed on the second layer, and the reflected beam 26a is The light is only scattered by the pattern of the diffraction grating 23a formed in the first layer after being reflected by the pattern of the diffraction grating 23b formed in the second layer until it is emitted from the disk 2.
  • the number of layers from one surface to the selected layer is 4 to 6
  • the number of layers from the other surface to the selected layer is 1 to 3
  • the former is larger than the latter. Therefore, if information is reproduced from the selected layer among the fourth to sixth layers using the incident beam 25b, the number of layers located between the other surface and the selected layer is small.
  • the amount of scattering received before exiting from the disk 2 is reduced.
  • the incident beam 25b is incident on the disk 2 until it is condensed on the fifth layer, and the reflected beam 26b is Between the time when it is reflected by the pattern of the diffraction grating 23e formed on the fifth layer and the time when it is emitted from the disk 2, it is only scattered by the pattern of the diffraction grating 23f formed on the sixth layer. Therefore, reproduction can be performed with a high signal-to-noise ratio for all of the first to sixth layers.
  • a diffraction grating pattern may be formed on the N layer in the thickness direction of the recording layer 22.
  • the target data to be reproduced is recorded in the nth layer, information is reproduced using the incident beam 25a when n ⁇ N / 2, and the incident beam 25b is used when n> N / 2. To reproduce the information.
  • the recording system circuit 102 includes a modulation circuit 30a, a recording signal generation circuit 31a, and a laser driving circuit 32a.
  • the modulation circuit 30a modulates a signal input from the outside as recording data according to a modulation rule when information is recorded on the disk 2.
  • the recording signal generation circuit 31a generates a recording signal for driving the laser 3 in the optical head 1a based on the signal modulated by the modulation circuit 30a.
  • the laser drive circuit 32a supplies a current corresponding to the recording signal to the laser 3 based on the recording signal generated by the recording signal generation circuit 31a when recording information on the disk 2. On the other hand, at the time of reproducing information from the disk 2, the laser drive circuit 32a supplies a constant current to the laser 3 so that the power of the emitted light from the laser 3 becomes constant.
  • the reproduction system circuit 103 includes an amplification circuit 33a, a reproduction signal processing circuit 34a, and a demodulation circuit 35a.
  • the amplifier circuit 33a amplifies the voltage signal output from the light receiving portions of the photodetectors 13a and 13b in the optical head 1a when reproducing information from the disk 2.
  • the reproduction signal processing circuit 34a performs generation, waveform equalization, and binarization of a reproduction signal recorded on the disk 2 in the form of a diffraction grating pattern based on the voltage signal amplified by the amplification circuit 33a.
  • the demodulating circuit 35a demodulates the signal binarized by the reproduction signal processing circuit 34a in accordance with a demodulation rule, and outputs it as reproduction data to the outside.
  • a voltage signal output from the light receiving unit of the photodetector 13a is used to generate a reproduction signal.
  • a voltage signal output from the light receiving unit of the photodetector 13b is used to generate a reproduction signal.
  • the shutter drive circuit 36 for driving the shutters 10a and 10b, when recording information on the disk 2, allows the light reflected by the polarizing beam splitter 8a to pass through the shutter 10a and the light transmitted through the polarizing beam splitter 8a by the shutter 10b. Let it pass.
  • the shutter 10a passes light reflected by the polarization beam splitter 8a and the shutter 10b blocks light transmitted through the polarization beam splitter 8a, or the shutter 10a is in the polarization beam splitter.
  • the light reflected by 8a is blocked, and the shutter 10b is in a state in which the light transmitted through the polarizing beam splitter 8a is allowed to pass.
  • the shutter drive circuit 36 when information is reproduced from the disk 2 using the light reflected by the polarization beam splitter 8a, the shutter drive circuit 36 causes the shutter 10a to pass the light reflected by the polarization beam splitter 8a and the shutter 10b is polarized.
  • the shutter drive circuit 36 receives the light reflected by the shutter 10a from the polarization beam splitter 8a. The light is blocked and the shutter 10b transmits the light transmitted through the polarization beam splitter 8a.
  • the objective lens drive circuit 39a transmits the light reflected by the polarization beam splitter 8a and the polarization beam splitter 8a in the recording layer of the disk 2 when recording information on the disk 2 and reproducing information from the disk 2.
  • a current corresponding to the set value is supplied to an electromagnetic drive type actuator not shown.
  • one of the objective lens 12a and the objective lens 12b in the optical head 1a is driven in the thickness direction and the radial direction of the disk 2.
  • the objective lens driving circuit 39a drives the objective lens 12a and uses the light transmitted through the polarizing beam splitter 8a to read information from the disk 2.
  • the objective lens drive circuit 39a drives the objective lens 12b.
  • the objective lens drive circuit 39a during recording on the disc 2, has the other of the light reflected by the polarization beam splitter 8a and the light transmitted through the polarization beam splitter 8a within the recording layer of the disc 2 with respect to one condensing position.
  • a current corresponding to the correction value is supplied to an electromagnetically driven actuator (not shown), and the objective lens 12a
  • the other of 12 b is driven in the thickness direction, radial direction, and tangential direction of the disk 2.
  • the objective lens driving circuit 39a drives the objective lens 12b and uses the light transmitted through the polarizing beam splitter 8a to read information from the disk 2.
  • the objective lens drive circuit 39a drives the objective lens 12a.
  • the relay lens driving circuit 40 determines the condensing position of both the light reflected by the polarization beam splitter 8a and the light transmitted through the polarization beam splitter 8a in the recording layer of the disk 2.
  • a current corresponding to the amount of movement is supplied to an electromagnetically driven actuator (not shown), and the relay lens in the optical head 1a Both the interval between the convex lens 5b and the convex lens 5d constituting the system and the interval between the convex lens 5c and the convex lens 5e are changed.
  • the relay lens driving circuit 40 collects one of the condensing positions of the light reflected by the polarizing beam splitter 8a and the light transmitted through the polarizing beam splitter 8a in the recording layer of the disk 2 when reproducing information from the disk 2. Is moved in the thickness direction of the disk 2 and one of them is focused on a selected layer, a current corresponding to the amount of movement is supplied to an electromagnetically driven actuator (not shown), and the convex lens 5b and the convex lens 5d One of the interval and the interval between the convex lens 5c and the convex lens 5e is changed.
  • the relay lens driving circuit 40 changes the distance between the convex lens 5b and the convex lens 5d and transmits the light transmitted through the polarizing beam splitter 8a.
  • the relay lens driving circuit 40 changes the interval between the convex lens 5c and the convex lens 5e.
  • the positioner drive circuit 43 moves the positioner 27a on which the optical head 1a is mounted by a motor (not shown) in the radial direction of the disk 2, and the spindle drive circuit 44 moves the spindle 28 on which the disk 2 is mounted by a motor (not shown). Rotate.
  • FIG. 5 is a flowchart showing processing performed by the controller 29a when reproducing information from the disc 2 in the optical information reproducing apparatus 100 disclosed in FIGS.
  • the controller 29a has an MPU and incorporates a computer program for performing the processing shown in FIG.
  • the controller 29a stores in advance the total number N of diffraction gratings formed in the thickness direction of the recording layer 22 determined by the disc standard.
  • the processing shown in FIG. 5 may be executed by, for example, analog computation in addition to being executed as a program.
  • the controller 29a drives the optical pickup 101 to read the format information stored in the first layer or the Nth layer of the disc 2 (step S202).
  • a list area in which data indicating the contents recorded on the disc corresponding to the TOC on the compact disc and the FAT on the hard disc is referred to as format information in this specification.
  • the format information it is possible to know on which layer the target data to be reproduced is recorded.
  • it is assumed that the target data is recorded in the nth layer.
  • the incident beams 25a and 25b in FIG. 4 correspond to the light reflected by the polarization beam splitter 8a in FIG. 2 and the light transmitted through the polarization beam splitter 8a, respectively.
  • the controller 29a determines whether or not n ⁇ N / 2 (step S203). If n ⁇ N / 2, the shutter 10a passes the light reflected by the polarization beam splitter 8a and the shutter 10b blocks the light transmitted through the polarization beam splitter 8a so that information is reproduced using the incident beam 25a. Thus, the controller 29a drives the shutters 10a and 10b through the shutter drive circuit 36 (step S204).
  • step S203 If n ⁇ N / 2 is not satisfied in step S203, the shutter 10a blocks the light reflected by the polarization beam splitter 8a and the shutter 10b transmits the polarization beam splitter 8a so that information is reproduced using the incident beam 25b.
  • the controller 29a drives the shutters 10a and 10b through the shutter drive circuit 36 so as to allow light to pass (step S205).
  • the controller 29a that has reproduced information by the incident beam 25b selected in steps S204 and 205 repeats steps S202 to 206 until the reproduction is completed (step S207).
  • the total number N of layers may be odd or even.
  • the total number N of layers is an odd number, there is a layer that passes through the same number of layers even when reproducing from either side of the incident beams 25a and 25b.
  • N 5
  • step S203 of FIG. 5 it is determined that n ⁇ N / 2 is not satisfied, and the process proceeds to step S205. However, this may be advanced to step S204.
  • FIG. 6 is a conceptual diagram showing a configuration of an optical information reproducing apparatus 100b according to the second embodiment of the present invention.
  • the optical information reproducing apparatus 100b is an optical information reproducing apparatus for bit-type reflection hologram recording, and is a recording / reproducing apparatus that records and reproduces information on an optical recording medium.
  • the optical information reproducing apparatus 100b drives a spindle 28 on which the disk 2 is mounted and rotated, an optical pickup 101b that records and reproduces information by irradiating the rotating disk 2 with laser, and an optical pickup 101b and the spindle 28. Circuit (described later in detail).
  • the optical pickup 101b includes an optical head 1b and a positioner 27b on which the optical head 1b is mounted and moved between the inner peripheral side and the outer peripheral side of the disk 2.
  • the positioner 27 b is driven by a positioner driving circuit 43
  • the spindle 28 is driven by a spindle driving circuit 44.
  • the optical head 1b is driven by each of a recording system circuit 102, a reproduction system circuit 103, an active wavelength plate driving circuit 37a, an objective lens driving circuit 39a, and a relay lens driving circuit 40.
  • the controller 29b controls each of the recording system circuit 102, the reproduction system circuit 103, the active wavelength plate driving circuit 37a, the objective lens driving circuit 39a, the relay lens driving circuit 40, the positioner driving circuit 43, and the spindle driving circuit 44.
  • the other circuit operations are the same as those of the optical information reproducing apparatus 100 shown in FIG.
  • the processing performed by the controller 29b when reproducing information from the disc 2 is the same as the processing shown in the flowchart of FIG.
  • FIG. 7 is a conceptual diagram showing the configuration of the optical head 1b disclosed in FIG.
  • the optical head 1b includes a laser 3 that is a light source for recording and reproducing information with respect to the disk 2 and optical components described later.
  • the laser 3 is an external resonator type single mode semiconductor laser using a diffraction grating as an external resonator, and emits light having a wavelength of 405 nm.
  • the light emitted from the laser 3 is transmitted through an expander lens system constituted by the concave lens 4a and the convex lens 5a, the beam diameter is enlarged, and enters the active wave plate 11a.
  • the active wave plate 11a When recording information on the disk 2 which is an optical recording medium, the active wave plate 11a has the effect of a quarter wave plate for incident light.
  • the light incident on the active wave plate 11a passes through the active wave plate 11a and is converted from linearly polarized light to circularly polarized light.
  • About 50% is reflected as an S-polarized light by the polarizing beam splitter 8a, and about 50% is polarized beam splitter. 8a is transmitted as a P-polarized component.
  • the light reflected by the polarization beam splitter 8a is reflected by the mirror 9b, passes through the relay lens system constituted by the convex lenses 5b and 5d, becomes convergent light or divergent light, is reflected by the mirror 9d, and is a quarter wavelength plate.
  • 6b is converted from linearly polarized light to circularly polarized light, and is condensed in the recording layer of the disk 2 by the objective lens 12a.
  • the light transmitted through the polarizing beam splitter 8a is reflected by the mirror 9a, reflected by the mirror 9c, transmitted through the relay lens system constituted by the convex lenses 5c and 5e, and becomes divergent light or convergent light, and is reflected by the mirror 9e. Then, the light passes through the quarter-wave plate 6c, is converted from linearly polarized light to circularly polarized light, and is condensed in the recording layer of the disk 2 by the objective lens 12b.
  • the light reflected by the polarizing beam splitter 8a and the light transmitted through the polarizing beam splitter 8a are condensed and interfered at the same position in the recording layer of the disk 2, and a pattern of a minute diffraction grating is formed at the condensing position. It is formed.
  • the active wave plate 11a when reproducing information from the disk 2, the active wave plate 11a has the effect of a full wave plate or a half wave plate with respect to incident light.
  • the active wave plate 11a When the active wave plate 11a has the effect of a full wave plate with respect to incident light, the light incident on the active wave plate 11a is transmitted through the active wave plate 11a without changing the polarization state, and is transmitted to the polarizing beam splitter 8a. Nearly 100% is reflected as polarized light and is collected in the recording layer of the disk 2.
  • the light condensed in the recording layer of the disk 2 is reflected by the pattern of the diffraction grating formed at the condensing position, passes through the objective lens 12a in the reverse direction, passes through the quarter wavelength plate 6b, and is circularly polarized.
  • the active wave plate 11a has the effect of a half wave plate with respect to the incident light
  • the light incident on the active wave plate 11a is transmitted through the active wave plate 11a and the polarization direction is changed by 90 °.
  • the light is incident on the beam splitter 8 a as P-polarized light and almost 100% is transmitted and condensed in the recording layer of the disk 2.
  • the light condensed in the recording layer of the disk 2 is reflected by the pattern of the diffraction grating formed at the condensing position, passes through the objective lens 12b in the reverse direction, passes through the quarter wavelength plate 6c, and is circularly polarized.
  • the pattern of the diffraction grating has bit data information.
  • the condensing position of the light reflected by the polarizing beam splitter 8a and the light transmitted through the polarizing beam splitter 8a is moved in the thickness direction of the recording layer, and is diffracted not only in the in-plane direction but also in the thickness direction of the recording layer.
  • By forming a lattice pattern three-dimensional recording / reproduction can be performed.
  • the active wavelength plate 11a has a configuration in which a liquid crystal polymer is sandwiched between two glass substrates. Transparent electrodes for applying an alternating voltage to the liquid crystal polymer are formed on the surface of the two glass substrates on the liquid crystal polymer side.
  • the liquid crystal polymer has uniaxial refractive index anisotropy in which the direction of the optical axis is the longitudinal direction, ne is the refractive index for polarized light components (abnormal light components) parallel to the longitudinal direction, and is perpendicular to the longitudinal direction. If the refractive index for a polarized component (ordinary light component) in any direction is no, ne is larger than no.
  • the longitudinal direction of the liquid crystal polymer is substantially perpendicular to the optical axis of the incident light. Therefore, the refractive index of the liquid crystal polymer with respect to the incident light is ne for the polarization component parallel to the longitudinal direction of the liquid crystal polymer and no for the polarization component perpendicular to the liquid crystal polymer.
  • the active wave plate 11a has a half wave plate effect.
  • the longitudinal direction of the liquid crystal polymer is substantially parallel to the optical axis of the incident light. Therefore, the refractive index of the liquid crystal polymer with respect to incident light becomes no regardless of the polarization state.
  • the active wave plate 11a has the effect of a full wave plate.
  • the longitudinal direction of the liquid crystal polymer is an intermediate direction parallel to the direction perpendicular to the optical axis of the incident light. Therefore, the refractive index of the liquid crystal polymer with respect to the incident light is (ne + no) / 2 perpendicular to the polarization component parallel to the projection in the longitudinal direction of the liquid crystal polymer in the plane perpendicular to the optical axis of the incident light. No for the polarization component. At this time, the active wave plate 11a has the effect of a quarter wave plate.
  • the optical path of the incident beam on the disk 2 when information is recorded on the disk 2 is the same as that shown in FIG. Further, in the present embodiment, the optical paths of the incident beam to the disk 2 and the reflected beam from the disk 2 when information is reproduced from the disk 2 are the same as those shown in FIG.
  • the active wave plate driving circuit 37a is effective for the liquid crystal polymer of the active wave plate 11a so that the active wave plate 11a in the optical head 1b has the effect of a quarter wave plate when information is recorded on the disk 2.
  • an AC voltage having a value of V / 2 is applied and the active wave plate 11a has the effect of all wave plates at the time of reproducing information from the disk 2
  • the liquid crystal polymer of the active wave plate 11a is used.
  • An AC voltage having an effective value of V is applied.
  • no AC voltage is applied to the liquid crystal polymer of the active wave plate 11a.
  • the active wave plate driving circuit 37a When reproducing information from the disk 2 using the light reflected by the polarization beam splitter 8a, the active wave plate driving circuit 37a applies an AC voltage having an effective value of V to the liquid crystal polymer so that the active wave plate 11a is completely removed. It has a wave plate effect. When reproducing information from the disk 2 using light transmitted through the polarizing beam splitter 8a, the active wave plate driving circuit 37a does not apply an AC voltage to the liquid crystal polymer, and the active wave plate 11a is a half wave plate. Try to have an effect.
  • FIG. 8 is a conceptual diagram showing a configuration of an optical information reproducing apparatus 100c according to the third embodiment of the present invention.
  • the optical information reproducing apparatus 100c is an optical information reproducing apparatus for recording a page type reflection hologram, and is a recording / reproducing apparatus for recording and reproducing information on an optical recording medium.
  • the optical information reproducing apparatus 100c drives a spindle 28 on which the disk 2 is mounted and rotated, an optical pickup 101c that records and reproduces information by irradiating the rotating disk 2 with laser, and an optical pickup 101c and the spindle 28. Circuit (described later in detail).
  • the optical pickup 101c includes an optical head 1c and a positioner 27c on which the optical head 1c is mounted and moved between the inner peripheral side and the outer peripheral side of the disk 2.
  • the positioner 27 c is driven by a positioner driving circuit 43, and the spindle 28 is driven by a spindle driving circuit 44.
  • the optical head 1c is driven by each of a laser drive circuit 32b, a recording system circuit 102b, a reproduction system circuit 103b, an active wavelength plate drive circuit 37b, an objective lens drive circuit 39a, and a relay lens drive circuit 40.
  • the operations of the laser drive circuit 32b, the recording system circuit 102b, the reproduction system circuit 103b, and the active wavelength plate drive circuit 37b will be described later.
  • the controller 29c includes the laser drive circuit 32b, the recording system circuit 102b, the reproduction system circuit 103b, the active wavelength plate drive circuit 37b, the objective lens drive circuit 39a, the relay lens drive circuit 40, the positioner drive circuit 43, and the spindle drive circuit 44. Control each one.
  • the other circuit operations are the same as those of the optical information reproducing apparatus 100 shown in FIG.
  • the processing performed by the controller 29c when reproducing information from the disc 2 is the same as the processing shown in the flowchart of FIG.
  • FIG. 9 is a conceptual diagram showing the configuration of the optical head 1c disclosed in FIG.
  • the optical head 1c includes a laser 3 that is a light source for recording and reproducing information with respect to the disk 2 and optical components described later.
  • the laser 3 is an external resonator type single mode semiconductor laser using a diffraction grating as an external resonator, and emits light having a wavelength of 405 nm.
  • the light emitted from the laser 3 is transmitted through an expander lens system constituted by the concave lens 4a and the convex lens 5a, the beam diameter is expanded, and enters the active wave plate 11b.
  • the active wave plate 11b When recording information on the disk 2 that is an optical recording medium, the active wave plate 11b has the effect of a quarter wave plate for incident light, and the active wave plate 11a is a half wave plate for incident light. Has the effect of all wave plates.
  • the light incident on the active wave plate 11b is transmitted from the active wave plate 11b and converted from linearly polarized light to circularly polarized light. About 50% is transmitted through the polarizing beam splitter 8d as a P-polarized component, and about 50% is polarized beam splitter. Reflected as an S-polarized component at 8d.
  • the light transmitted through the polarizing beam splitter 8d and the light reflected by the polarizing beam splitter 8d correspond to signal light and reference light, respectively.
  • the light that has passed through the polarizing beam splitter 8d passes through the half-wave plate 7b, changes its polarization direction by 90 °, is reflected by the mirror 9f, and the spatial light modulator 18 modulates the intensity distribution in the cross section according to the recorded information. Then, it enters the polarizing beam splitter 8e as S-polarized light, and almost 100% is reflected and enters the active wave plate 11a.
  • the light reflected by the polarizing beam splitter 8d passes through the half-wave plate 7c, changes its polarization direction by 90 °, is reflected by the mirror 9g, and the phase distribution in the cross section is random by the random phase plate 19. After being modulated, it enters the polarization beam splitter 8e as P-polarized light, and almost 100% is transmitted, and then enters the active wave plate 11a.
  • the active wave plate 11a When the active wave plate 11a has the effect of a half wave plate with respect to incident light, the signal light that is reflected by the polarization beam splitter 8e and incident on the active wave plate 11a is transmitted through the active wave plate 11a. As a result, the polarization direction changes by 90 ° and enters the polarization beam splitter 8a as P-polarized light, and almost 100% is transmitted. Further, the reference light, which is light that has passed through the polarizing beam splitter 8e and entered the active wave plate 11a, passes through the active wave plate 11a, changes its polarization direction by 90 °, and enters the polarizing beam splitter 8a as S-polarized light. Almost 100% is reflected.
  • the signal light that is reflected by the polarization beam splitter 8e and incident on the active wave plate 11a is polarized in the active wave plate 11a. Is transmitted without change, and is incident on the polarization beam splitter 8a as S-polarized light, and almost 100% is reflected.
  • the reference light which is light that has passed through the polarizing beam splitter 8e and entered the active wave plate 11a, passes through the active wave plate 11a without changing its polarization state, and enters the polarizing beam splitter 8a as P-polarized light. Almost 100% is transmitted.
  • the light reflected by the polarization beam splitter 8a is reflected by the mirror 9b, passes through the relay lens system constituted by the convex lenses 5b and 5d, becomes convergent light or divergent light, is reflected by the mirror 9d, and is a quarter wavelength plate.
  • 6b is converted from linearly polarized light to circularly polarized light, and is condensed in the recording layer of the disk 2 by the objective lens 12a.
  • the light transmitted through the polarizing beam splitter 8a is reflected by the mirror 9a, reflected by the mirror 9c, transmitted through the relay lens system constituted by the convex lenses 5c and 5e, and becomes divergent light or convergent light, and is reflected by the mirror 9e. Then, the light passes through the quarter-wave plate 6c, is converted from linearly polarized light to circularly polarized light, and is condensed in the recording layer of the disk 2 by the objective lens 12b.
  • the light reflected by the polarizing beam splitter 8a and the light transmitted through the polarizing beam splitter 8a are condensed at the same position in the recording layer of the disk 2 and interfere to form a hologram at the condensing position.
  • the active wave plate 11b when reproducing information from the disk 2, the active wave plate 11b has the effect of a full wave plate for incident light, and the active wave plate 11a is a half wave plate or full wave plate for incident light. With the effect.
  • the light that has entered the active wave plate 11b passes through the active wave plate 11b without changing its polarization state, and enters the polarization beam splitter 8d as S-polarized light, and is reflected almost 100%.
  • the light reflected by the polarization beam splitter 8d corresponds to the reference light. This light passes through the polarization beam splitter 8e and enters the active wave plate 11a.
  • the active wavelength plate 11a When the active wavelength plate 11a has the effect of a half-wave plate with respect to incident light, the reference light that is light that has passed through the polarization beam splitter 8e and entered the active wavelength plate 11a is transmitted through the active wavelength plate 11a. As a result, the polarization direction changes by 90 ° and enters the polarization beam splitter 8a as S-polarized light, and almost 100% is reflected and collected in the recording layer of the disk 2.
  • the light condensed in the recording layer of the disk 2 is reflected by the hologram formed at the condensing position, passes through the objective lens 12a in the reverse direction, passes through the quarter-wave plate 6b, and changes from circularly polarized light to linearly polarized light.
  • Is reflected by the mirror 9d passes through the relay lens system constituted by the convex lenses 5d and 5b in the reverse direction, is reflected by the mirror 9b, enters the polarization beam splitter 8a as P-polarized light, and transmits almost 100%. .
  • the reference light that is the light that has passed through the polarization beam splitter 8e and entered the active wave plate 11a is polarized in the active wave plate 11a. Is transmitted without change, enters the polarization beam splitter 8a as P-polarized light, and almost 100% is transmitted and condensed in the recording layer of the disk 2.
  • the light condensed in the recording layer of the disk 2 is reflected by the hologram formed at the condensing position, passes through the objective lens 12b in the reverse direction, passes through the quarter wavelength plate 6c, and is linearly polarized from circularly polarized light.
  • Is reflected by the mirror 9e passes through the relay lens system constituted by the convex lenses 5e and 5c in the reverse direction, is reflected by the mirror 9c, is reflected by the mirror 9a, and enters the polarization beam splitter 8a as S-polarized light. Almost 100% is reflected.
  • the light reflected by the hologram formed at the condensing position and transmitted through the polarization beam splitter 8a and the light reflected by the polarization beam splitter 8a are transmitted through the expander lens system constituted by the convex lens 5h and the concave lens 4b.
  • the diameter is reduced, and the image sensor 20 detects the intensity distribution in the cross section modulated according to the reproduction information.
  • the hologram has page data information.
  • the converging position of the light reflected by the polarization beam splitter 8a and the light transmitted through the polarization beam splitter 8a is moved in the thickness direction of the recording layer, and the hologram is formed in multiple layers not only in the in-plane direction of the recording layer but also in the thickness direction. By forming, three-dimensional recording / reproduction can be performed.
  • the active wave plate 11b has a configuration in which a liquid crystal polymer is sandwiched between two glass substrates, similarly to the active wave plate 11a.
  • the optical path of the incident beam on the disk 2 when information is recorded on the disk 2 is the same as that shown in FIG. Further, in the present embodiment, the optical paths of the incident beam to the disk 2 and the reflected beam from the disk 2 when information is reproduced from the disk 2 are the same as those shown in FIG. However, the patterns of the diffraction gratings 23a to 23f in FIG. 4 are replaced with holograms.
  • the incident beam 24a in FIG. 3A and the incident beam 24c in FIG. 3B correspond to the light reflected by the polarization beam splitter 8a in FIG. 9, and the incident beam 24b in FIG.
  • the incident beam 24d in FIG. 9 corresponds to the light transmitted through the polarizing beam splitter 8a in FIG. 4A corresponds to the light reflected by the polarizing beam splitter 8a in FIG. 9, and the incident beam 25b in FIG. 4B changes to the light transmitted through the polarizing beam splitter 8a in FIG. Correspond.
  • holograms are formed in six layers in the thickness direction of the recording layer 22.
  • the first to third layers on which information is recorded are formed using the incident beam 24a as the reference light and the incident beam 24b as the signal light, and the incident beam 24c is used as the signal light.
  • the fourth to sixth layers on which information is recorded are formed using the incident beam 24d as reference light.
  • information is reproduced from a selected layer among the first to third layers using the incident beam 25a as reference light, and the incident beam 25b is used as reference light.
  • Information is reproduced from a selected layer among the fourth to sixth layers.
  • a hologram may be formed on the N layer in the thickness direction of the recording layer 22.
  • the first to (N / 2) layers on which information is recorded are formed using the incident beam 24a as reference light and the incident beam 24b as signal light.
  • the (N / 2 + 1) th to Nth layers in which information is recorded may be formed using the signal light 24c and the incident beam 24d as reference light.
  • information is reproduced from a selected layer among the first to (N / 2) layers using the incident beam 25a as reference light, and the incident beam 25b is used as reference light.
  • the information may be reproduced from a selected layer among the (N / 2 + 1) th layer to the Nth layer.
  • the laser drive circuit 32b supplies a constant current to the laser 3 so that the power of the emitted light from the laser 3 is constant when recording information on the disk 2 and reproducing information from the disk 2. 3 is driven.
  • the recording system circuit 102b includes a modulation circuit 30b, a recording signal generation circuit 31b, and a spatial light modulator driving circuit 42.
  • the modulation circuit 30b modulates a signal input from the outside as recording data according to a modulation rule when information is recorded on the disk 2.
  • the recording signal generation circuit 31b generates a recording signal for driving the spatial light modulator 18 in the optical head 1c based on the signal modulated by the modulation circuit 30b.
  • the spatial light modulator driving circuit 42 drives the spatial light modulator 18 by supplying a voltage corresponding to the recording signal to each pixel of the spatial light modulator 18 based on the recording signal generated by the recording signal generating circuit 31b. To do.
  • the reproduction system circuit 103b includes an amplification circuit 33b, a reproduction signal processing circuit 34b, and a demodulation circuit 35b.
  • the amplifier circuit 33b amplifies a voltage signal output from each pixel of the image sensor 20 in the optical head 1c when reproducing information from the disk 2.
  • the reproduction signal processing circuit 34b performs generation, waveform equalization, and binarization of a reproduction signal recorded in the form of a hologram on the disk 2 based on the voltage signal amplified by the amplification circuit 33b.
  • the demodulating circuit 35b demodulates the signal binarized by the reproduction signal processing circuit 34b in accordance with a demodulation rule, and outputs it as reproduction data to the outside.
  • the active wave plate driving circuit 37b is effective for the liquid crystal polymer of the active wave plate 11b so that the active wave plate 11b in the optical head 1c has the effect of a quarter wave plate when information is recorded on the disk 2.
  • An AC voltage having a value of V / 2 is applied, and an AC voltage is applied to the liquid crystal polymer of the active wave plate 11a so that the active wave plate 11a in the optical head 1c has the effect of a half wave plate or a full wave plate. Is applied or an AC voltage having an effective value of V is applied.
  • the active wavelength plate driving circuit 37b uses the liquid crystal polymer.
  • the active wave plate 11a is made to have the effect of a half wave plate without applying an AC voltage.
  • the active wave plate driving circuit 37b has an effective value for the liquid crystal polymer. An AC voltage of V is applied so that the active wave plate 11a has the effect of all wave plates.
  • the active wave plate driving circuit 37b applies an AC voltage having an effective value of V to the liquid crystal polymer of the active wave plate 11b during the reproduction of information from the disk 2 so that the active wave plate 11b has the effect of the full wave plate.
  • the active wave plate 11a has the effect of a half wave plate without applying an AC voltage to the liquid crystal polymer of the active wave plate 11a.
  • the active wave plate driving circuit 37b when information is reproduced from the disk 2 using the light reflected by the polarization beam splitter 8a as the reference light, the active wave plate driving circuit 37b does not apply an AC voltage to the liquid crystal polymer, and the active wave plate 11a A half-wave plate effect is provided.
  • the active wave plate driving circuit 37b applies an AC voltage having an effective value of V to the liquid crystal polymer to thereby activate the active wave plate 11a. Has the effect of a full wave plate.
  • FIG. 10 is a conceptual diagram showing a configuration of an optical information reproducing device 100d according to the fourth embodiment of the present invention.
  • the optical information reproducing apparatus 100d is an optical information reproducing apparatus for bit-type reflection hologram recording, and is a recording / reproducing apparatus for recording and reproducing information on an optical recording medium.
  • the optical information reproducing apparatus 100d drives a spindle 28 on which the disk 2 is mounted and rotated, an optical pickup 101d that records and reproduces information by irradiating the rotating disk 2 with a laser, and the optical pickup 101d and the spindle 28. Circuit (described later in detail).
  • the optical pickup 101d includes an optical head 1d and a positioner 27d that mounts the optical head 1d and moves between the inner peripheral side and the outer peripheral side of the disk 2.
  • the positioner 27 d is driven by a positioner driving circuit 43
  • the spindle 28 is driven by a spindle driving circuit 44.
  • the optical head 1d is driven by each of the recording system circuit 102, the reproduction system circuit 103, the shutter drive circuit 36, the active wavelength plate drive circuit 37c, the semiconductor laser drive circuit 41, the objective lens system circuit 110, and the relay lens drive circuit 40. Is done.
  • the operations of the active wavelength plate driving circuit 37c, the semiconductor laser driving circuit 41, and the objective lens system circuit 110 will be described later.
  • the operation of the other circuits is as described in the first embodiment of the optical information reproducing apparatus of the present invention shown in FIG. Further, the process performed by the controller 29d when reproducing information from the disk 2 is the same as the process shown in the flowchart of FIG.
  • FIG. 11 is a conceptual diagram showing the configuration of the optical head 1d disclosed in FIG.
  • the optical head 1d includes an active wavelength plate 11c, a polarizing beam splitter 8f, a convex lens 5i, a cylindrical lens 14a, and a photodetector 13d in the optical path of the light reflected by the polarizing beam splitter 8b in the optical head 1a shown in FIG.
  • An active wavelength plate 11d, a polarizing beam splitter 8g, a convex lens 5j, a cylindrical lens 14b, and a photodetector 13e are added in the optical path of the light reflected by the polarizing beam splitter 8c, and the mirror 9d and the mirror 9e are respectively connected to the interference filter 17a,
  • the light that passes through the interference filter 17b is replaced with the semiconductor laser 15a, the convex lens 5k, the beam splitter 16a, the convex lens 5m, the cylindrical lens 14c, and the photodetector 13f in the optical path of the light that passes through the interference filter 17a.
  • Interference filters 17a and 17b reflect light having a wavelength of 405 nm and transmit light having a wavelength of 650 nm. Other operations of the optical system are as described in the optical head 1a shown in FIG.
  • the active wave plates 11c and 11d have the effect of full wave plates for incident light.
  • the light reflected by the polarization beam splitter 8a and collected in the recording layer of the disk 2 is transmitted through the disk 2, passes through the objective lens 12b in the reverse direction, and is transmitted through the quarter-wave plate 6c.
  • the light transmitted through the polarization beam splitter 8a and condensed in the recording layer of the disk 2 passes through the disk 2, passes through the objective lens 12a in the reverse direction, and passes through the quarter wavelength plate 6b to be circular.
  • Polarized light is converted to linearly polarized light, reflected by the interference filter 17a, passes through the relay lens system constituted by the convex lenses 5d and 5b in the reverse direction, and enters the polarizing beam splitter 8b as S-polarized light, and almost 100% is reflected.
  • the light is transmitted through the active wave plate 11c without changing its polarization state, is incident on the polarization beam splitter 8f as S-polarized light, and is almost 100% reflected, and is not reflected by the anamorphic lens system constituted by the convex lens 5i and the cylindrical lens 14a. A point aberration is given and it is condensed on the light receiving part of the photodetector 13d.
  • the photodetector 13e is provided in the middle of two focal lines formed by an anamorphic lens system composed of a convex lens 5j and a cylindrical lens 14b, and a dividing line and a tangential direction corresponding to the radial direction of the disk 2
  • the light receiving section is divided into four by a dividing line corresponding to. Based on the voltage signal output from each light receiving unit, the deviation of the condensing position of the light transmitted through the polarizing beam splitter 8a with respect to the condensing position of the light reflected by the polarizing beam splitter 8a in the recording layer of the disk 2 is shifted. Detected.
  • the photodetector 13d is provided in the middle of two focal lines formed by the anamorphic lens system constituted by the convex lens 5i and the cylindrical lens 14a, and a dividing line corresponding to the radial direction of the disk 2 and The light receiving unit is divided into four by dividing lines corresponding to the tangential direction. Based on the voltage signal output from each light receiving unit, the deviation of the condensing position of the light reflected by the polarizing beam splitter 8a from the condensing position of the light transmitted through the polarizing beam splitter 8a in the recording layer of the disk 2 is shifted. Detected.
  • a thickness direction displacement signal which is a condensing position deviation in the thickness direction of the disk 2 is detected by a known astigmatism method
  • a radial position deviation signal which is a condensing position deviation in the radial direction of the disk 2 is known.
  • a tangential displacement signal that is detected by the radial push-pull method and is a converging position displacement in the tangential direction of the disk 2 is detected by a known tangential push-pull method.
  • the active wave plates 11c and 11d have the effect of a half wave plate with respect to incident light.
  • the shutter 10a passes the light reflected by the polarizing beam splitter 8a and the shutter 10b blocks the light transmitted through the polarizing beam splitter 8a, the light is reflected by the polarizing beam splitter 8a and collected in the recording layer of the disk 2.
  • the reflected light is reflected by the pattern of the diffraction grating formed at the condensing position, is incident on the polarizing beam splitter 8b as S-polarized light, is reflected by almost 100%, is transmitted through the active wave plate 11c, and has a polarization direction of 90 °. It changes, enters into the polarization beam splitter 8f as P-polarized light, and almost 100% is transmitted, and is condensed on the light receiving portion of the photodetector 13a by the convex lens 5f.
  • the shutter 10a blocks the light reflected by the polarizing beam splitter 8a and the shutter 10b allows the light transmitted through the polarizing beam splitter 8a to pass therethrough, the light passes through the polarizing beam splitter 8a and is collected in the recording layer of the disk 2.
  • the emitted light is reflected by the pattern of the diffraction grating formed at the condensing position, is incident on the polarizing beam splitter 8c as S-polarized light, is reflected by almost 100%, is transmitted through the active wavelength plate 11d, and has a polarization direction. It changes by 90 ° and enters the polarization beam splitter 8g as P-polarized light and transmits almost 100%, and is condensed on the light receiving portion of the photodetector 13b by the convex lens 5g.
  • Semiconductor lasers 15a and 15b emit light having a wavelength of 650 nm.
  • the light emitted from the semiconductor laser 15a passes through the convex lens 5k and is converted from divergent light into parallel light. About 50% of the light passes through the beam splitter 16a, passes through the interference filter 17a and the quarter-wave plate 6b, and the objective.
  • the light is condensed on the first reference surface of the disk 2 by the lens 12a.
  • the light condensed on the first reference surface of the disk 2 is reflected by the first reference surface of the disk 2, passes through the objective lens 12a in the reverse direction, and passes through the quarter-wave plate 6b and the interference filter 17a.
  • the light emitted from the semiconductor laser 15b is transmitted through the convex lens 5l and converted from the divergent light into parallel light, and about 50% is transmitted through the beam splitter 16b and transmitted through the interference filter 17b and the quarter wavelength plate 6c.
  • the light is condensed on the second reference surface of the disk 2 by the objective lens 12b.
  • the light condensed on the second reference surface of the disk 2 is reflected by the second reference surface of the disk 2, passes through the objective lens 12b in the reverse direction, and passes through the quarter-wave plate 6c and the interference filter 17b.
  • Approximately 50% is reflected by the beam splitter 16b is given astigmatism by the anamorphic lens system including the convex lens 5n and the cylindrical lens 14d, and is collected on the light receiving portion of the photodetector 13g.
  • the photodetector 13f is provided in the middle of two focal lines formed by an anamorphic lens system composed of a convex lens 5m and a cylindrical lens 14c, and a dividing line and a tangential direction corresponding to the radial direction of the disk 2
  • the light receiving section is divided into four by a dividing line corresponding to.
  • a groove parallel to the tangential direction representing the first reference position is formed on the first reference surface of the disk 2, and the first reference position of the disk 2 is based on the voltage signal output from each light receiving unit.
  • the deviation of the condensing position of the light emitted from the semiconductor laser 15a is detected.
  • the deviation of the light collection position of the light reflected by the polarization beam splitter 8a in the recording layer of the disk 2 with respect to the first reference position is detected.
  • the photodetector 13g is provided in the middle of two focal lines formed by the anamorphic lens system constituted by the convex lens 5n and the cylindrical lens 14d, and the dividing line corresponding to the radial direction of the disk 2 and The light receiving unit is divided into four by dividing lines corresponding to the tangential direction.
  • a groove parallel to the tangential direction representing the second reference position is formed on the second reference surface of the disk 2, and the second reference position of the disk 2 is based on the voltage signal output from each light receiving unit.
  • the deviation of the condensing position of the light emitted from the semiconductor laser 15b is detected.
  • the deviation of the condensing position of the light transmitted through the polarization beam splitter 8a in the recording layer of the disc 2 with respect to the second reference position is detected.
  • a focus error signal that is a condensing position deviation in the thickness direction of the disk 2 is detected by a known astigmatism method, and a track error signal that is a condensing position deviation in the radial direction of the disk 2 is detected by a known radial push-pull method. Detected.
  • the first reference surface of the disk 2 is a boundary surface between the substrate 21a and the recording layer 22 shown in FIGS. 3 and 4, and the second reference surface of the disk 2 is shown in FIGS.
  • This is a boundary surface between the substrate 21 b and the recording layer 22.
  • a dielectric multilayer film that transmits light having a wavelength of 405 nm and reflects light having a wavelength of 650 nm is formed on the boundary surface between the substrate 21 a and the recording layer 22 and the boundary surface between the substrate 21 b and the recording layer 22.
  • the active wave plate 11c and the active wave plate 11d have a configuration in which a liquid crystal polymer is sandwiched between two glass substrates, like the active wave plate 11a.
  • the optical path of the incident beam on the disk 2 when information is recorded on the disk 2 is the same as that shown in FIG. Further, in the present embodiment, the optical paths of the incident beam to the disk 2 and the reflected beam from the disk 2 when information is reproduced from the disk 2 are the same as those shown in FIG.
  • the active wave plate driving circuit 37c applies an AC voltage having an effective value of V to the liquid crystal polymer of the active wave plates 11c and 11d in the optical head 1d.
  • 11d has the effect of a full wave plate.
  • an AC voltage is not applied to the liquid crystal polymer of the active wave plates 11c and 11d in the optical head 1d so that the active wave plates 11c and 11d have the effect of a half wave plate.
  • the semiconductor laser drive circuit 41 is configured so that the power of the emitted light from the semiconductor lasers 15a and 15b in the optical head 1d is constant when information is recorded on the disk 2 and when information is reproduced from the disk 2. A constant current is supplied to 15a and 15b for driving.
  • the objective lens system circuit 110 includes an amplification circuit 33c, an error signal generation circuit 38, and an objective lens driving circuit 39b.
  • the amplifier circuit 33c amplifies the voltage signals output from the light receiving portions of the photodetectors 13f and 13g in the optical head 1d when information is recorded on the disk 2 and when information is reproduced from the disk 2.
  • the error signal generation circuit 38 generates a focus error signal and a track error signal for driving one of the objective lenses 12a and 12b in the optical head 1d based on the voltage signal amplified by the amplification circuit 33c.
  • the objective lens drive circuit 39b is configured so that the disc 2 with respect to the first reference position or the second reference position of one condensing position of the light reflected by the polarization beam splitter 8a and the transmitted light in the recording layer of the disc 2 is used.
  • a focus error signal is sent to an electromagnetically driven actuator (not shown) based on the focus error signal and the track error signal generated by the error signal generation circuit 38. Then, a current corresponding to the track error signal is supplied to drive one of the objective lenses 12 a and 12 b in the thickness direction and the radial direction of the disk 2.
  • the objective lens drive circuit 39b when information is reproduced from the disk 2 by using the light reflected by the polarization beam splitter 8a, the objective lens drive circuit 39b has a first reference position of the condensing position of the light reflected by the polarization beam splitter 8a.
  • the objective lens drive circuit 39b sets the polarization beam splitter 8a to The objective lens 12b is driven in order to set the deviation of the condensed position of the transmitted light with respect to the second reference position to a predetermined value.
  • the amplifying circuit 33c amplifies voltage signals output from the light receiving portions of the photodetector 13d and the photodetector 13e in the optical head 1d when information is recorded on the disk 2. Based on the voltage signal amplified by the amplifier circuit 33c, the error signal generation circuit 38 is a thickness direction positional deviation signal, a radial direction positional deviation signal, a tangential direction positional position signal for driving the other of the objective lens 12a and the objective lens 12b. A shift signal is generated.
  • the objective lens drive circuit 39b has a thickness of the disc 2 at the other condensing position with respect to one condensing position of the light reflected by the polarizing beam splitter 8a and the light transmitted through the polarizing beam splitter 8a in the recording layer of the disc 2.
  • an electromagnetic wave (not shown) A current corresponding to the thickness direction positional deviation signal, the radial direction positional deviation signal, and the tangential direction positional deviation signal is supplied to the drive type actuator, and the other one of the objective lens 12a and the objective lens 12b is connected in the thickness direction of the disk 2. Drive in radial and tangential directions.
  • the objective lens drive circuit 39b sets the polarization beam splitter 8a for the light condensing position of the light reflected by the polarization beam splitter 8a.
  • the objective lens drive circuit 39b The objective lens 12a is driven to correct the deviation of the light collection position of the light reflected by the polarization beam splitter 8a with respect to the light collection position of the light transmitted through the splitter 8a.
  • optical information reproducing apparatuses are all recording / reproducing apparatuses for recording and reproducing information with respect to an optical recording medium.
  • those having the above are also included in the scope of the present invention.
  • It can be used in an optical information reproducing apparatus that reproduces information from an optical recording medium on which information is recorded three-dimensionally.
  • FIG. 3 is a conceptual diagram showing an optical path of an incident beam on a disc when information is recorded on the disc in the optical information reproducing apparatus disclosed in FIGS.
  • FIG. 3 is a conceptual diagram showing optical paths of an incident beam to a disk and a reflected beam from the disk when reproducing information from the disk in the optical information reproducing apparatus disclosed in FIGS.
  • 5 is a flowchart showing processing performed by a controller when reproducing information from a disc in the optical information reproducing apparatus disclosed in FIGS.
  • Optical head 2 Disc 3 Laser 10a, 10b Shutter 11a, 11b Active wave plate 13a, 13b, 13c Photo detector 13d, 13e, 13f, 13g Photo detector 20 Imaging element 29a, 29b, 29c, 29d controller 100, 100b, 100c, 100d optical information reproducing apparatus 101, 101b, 101c, 101d optical pickup 102, 102b recording system circuit 103, 103b reproducing system circuit 110 objective lens system circuit

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Recording Or Reproduction (AREA)
  • Optical Head (AREA)

Abstract

La présente invention concerne un dispositif de reproduction d'informations optique. Dans ce dispositif, il est possible de réduire une quantité de lumière diffusée après que la lumière est entrée dans un support d'enregistrement optique contenant des informations enregistrées en trois dimensions jusqu'à ce que la lumière soit sortie. Le dispositif de reproduction d'informations optique (100) comprend une source de lumière (3) qui produit un faisceau de reproduction permettant d'exposer un support d'enregistrement optique (2) de façon à reproduire des données provenant du support d'enregistrement optique (2), un système optique (1a) qui dirige le faisceau de reproduction vers une première surface et une seconde surface du support d'enregistrement optique, un moyen de commutation de chemin optique (10a et 10b) qui arrête un des faisceaux de reproduction dirigés vers la première surface et la seconde surface par le système optique, ainsi qu'un moyen d'évaluation (29) qui évalue une couche où sont enregistrées dans le support d'enregistrement optique les données cibles devant être reproduites et commande le moyen de commutation de chemin optique en fonction du résultat de l'évaluation.
PCT/JP2009/050121 2008-01-16 2009-01-08 Dispositif de reproduction d'informations optique, dispositif de tête optique, procédé de reproduction d'informations optique et programme de reproduction d'informations WO2009090905A1 (fr)

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Cited By (1)

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JP2012150301A (ja) * 2011-01-20 2012-08-09 Hitachi Ltd 光学装置

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JPS63161542A (ja) * 1986-12-25 1988-07-05 Sony Corp デイスクプレ−ヤ
JPH04360033A (ja) * 1991-06-06 1992-12-14 Ricoh Co Ltd 光ディスク装置
JPH08287474A (ja) * 1995-04-10 1996-11-01 Sony Corp データ記録媒体およびそのデータ記録媒体を使用する記録／再生装置
JPH11133843A (ja) * 1997-10-24 1999-05-21 Sony Corp 光情報記録装置および方法
JP2000163790A (ja) * 1998-11-26 2000-06-16 Olympus Optical Co Ltd 光ピックアップ装置
JP2002352467A (ja) * 2001-05-22 2002-12-06 Funai Electric Co Ltd 光ピックアップ装置
WO2006082678A1 (fr) * 2005-01-06 2006-08-10 National University Corporation Kobe University Dispositif d’enregistrement optique de donnees (dispositif de memoire holographique a reflexion)

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JP4748043B2 (ja) * 2006-12-01 2011-08-17 富士ゼロックス株式会社 光記録装置、光記録方法、記録媒体及び再生方法
JP4389184B2 (ja) * 2007-06-29 2009-12-24 ソニー株式会社 光情報記録再生装置

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Publication number Priority date Publication date Assignee Title
JPS63161542A (ja) * 1986-12-25 1988-07-05 Sony Corp デイスクプレ−ヤ
JPH04360033A (ja) * 1991-06-06 1992-12-14 Ricoh Co Ltd 光ディスク装置
JPH08287474A (ja) * 1995-04-10 1996-11-01 Sony Corp データ記録媒体およびそのデータ記録媒体を使用する記録／再生装置
JPH11133843A (ja) * 1997-10-24 1999-05-21 Sony Corp 光情報記録装置および方法
JP2000163790A (ja) * 1998-11-26 2000-06-16 Olympus Optical Co Ltd 光ピックアップ装置
JP2002352467A (ja) * 2001-05-22 2002-12-06 Funai Electric Co Ltd 光ピックアップ装置
WO2006082678A1 (fr) * 2005-01-06 2006-08-10 National University Corporation Kobe University Dispositif d’enregistrement optique de donnees (dispositif de memoire holographique a reflexion)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012150301A (ja) * 2011-01-20 2012-08-09 Hitachi Ltd 光学装置

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