JP2010151907A - Optical information recording medium, optical information recording/reproducing apparatus, and optical information recording/reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hologram recording medium that reproduces information with phase conjugate light without requiring a mirror and its driving section for obtaining phase conjugate light and does not reduce the recording density. <P>SOLUTION: This recording medium includes a recording layer 402 on which an interference pattern is recorded, and a light absorbing/reflecting layer 406 can reversibly change between a first state of absorbing signal light 4B and reference light 4A having passed the recording layer during recording the information and a second state of reflecting the reference light during reproducing the information. The recording medium generates the reference light reflected on the light absorbing/reflecting layer as the phase conjugate light. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical information recording medium for recording information using holography, an optical information recording / reproducing apparatus using the medium, and a method for recording / reproducing optical information using the medium.

  At present, the Blu-ray Disc (BD) standard using a blue-violet semiconductor laser has made it possible to commercialize an optical disc having a recording density of about 50 GB even for consumer use. In the future, it is desired to increase the capacity of optical discs to the same extent as HDD (Hard Disc Drive) capacity of 100 GB to 1 TB.

  However, in order to realize such an ultra-high density with an optical disc, a high-density technology by a new method different from the high-density technology by shortening the wavelength and increasing the objective lens NA is necessary.

  While research on next-generation storage technology is underway, hologram recording technology that records digital information using holography is attracting attention. Hologram recording technology is a method in which signal light having page data information two-dimensionally modulated by a spatial light modulator is superimposed on reference light inside the recording medium, and the interference fringe pattern generated at that time is placed in the recording medium. This is a technique for recording information on a recording medium by causing refractive index modulation.

  At the time of reproducing information, if the recording medium is irradiated with the reference light used at the time of recording, the hologram recorded in the recording medium acts like a diffraction grating to generate diffracted light. This diffracted light is reproduced as the same light including the recorded signal light and phase information.

  The reproduced signal light is detected two-dimensionally at high speed using a photodetector such as a CMOS or CCD. As described above, the hologram recording technique enables two-dimensional information to be recorded on the optical recording medium at once by one hologram and further reproduces this information. Since the page data can be overwritten, large-capacity and high-speed information recording / reproduction can be achieved.

  As a hologram recording technique, for example, there is one described in Japanese Patent Application Laid-Open No. 2004-272268 (Patent Document 1). In this publication, a signal beam is condensed on an optical information recording medium by a lens, and simultaneously, a hologram is recorded by irradiating and collimating a reference beam of a parallel beam, and further determining the incident angle of the reference beam on the optical recording medium. A so-called angle multiplex recording method is described in which multiplex recording is performed by displaying different page data on a spatial light modulator while changing.

  In this publication, the interval between adjacent holograms can be shortened by condensing the signal light with a lens and providing an opening (spatial filter) at the beam waist, compared to the conventional angle multiplex recording system. Techniques for increasing recording density / capacity are described.

  Another hologram recording technique is, for example, WO 2004-102542 (Patent Document 2). In this publication, in one spatial light modulator, light from an inner pixel is signal light, light from an outer ring-shaped pixel is reference light, and both light beams are condensed on an optical recording medium with the same lens. An example is described in which a shift multiplexing method is used in which a hologram is recorded by causing signal light and reference light to interfere with each other in the vicinity of the focal plane of the lens.

  By the way, when reproducing information recorded on an optical information recording medium, it is possible to use an optical component such as a signal detection camera of a recording system as a reproducing system by using phase conjugate light of reference light. : Technical Digest ODS (2006), MA1. (Non-Patent Document 1).

  Further, in Japanese Patent Laid-Open No. 2002-170247 (Patent Document 3), a hologram recording medium has a reflection layer, and recording is performed on the hologram recording medium using phase conjugate light obtained by reflecting reference light on the reflection layer. A hologram recording / reproducing method for reproducing the recorded information is described.

Furthermore, Alan Hoskins et. al. : Technical Digest ISOM (2007) and We-J-P01 (Non-patent Document 2) do not reflect the signal light and the reference light when recording information, but reflect the reference light when reproducing the information. Thus, a reflection layer that generates the phase conjugate light has been proposed.
JP 2004-272268 A WO2004-102542 JP 2002-170247 A Ian Redmond: Technical Digest ODS (2006), MA1. Alan Hoskins et. al. : Technical Digest ISOM (2007), We-J-P01 Dimming mirror using magnesium-nickel alloy thin film, surface technology, Vol. 56, p. 882 (2005) Y. Fujiita et. al. : Technical Digest ISOM (2006), Mo-C-03

  According to the recording / reproducing method using the hologram recording medium described in Patent Document 3, since the reference light is reflected by the reflective layer during recording, the area irradiated with the recording medium is widened and the area of the recording is enlarged. There are challenges. Further, since the signal light is also reflected by the reflective layer, there is a problem that a hologram is newly formed on the recording medium by the reflected signal light. The hologram recording medium described in Patent Document 3 can prevent an increase in the size of the hologram recording / reproducing apparatus, but this problem causes a new problem that the recording density on the recording medium is reduced. The inventor found out.

  Non-Patent Document 2 merely suggests the possibility that the phase conjugate system is accommodated in the recording medium, and does not describe any specific configuration.

  Therefore, the present invention makes it possible to reproduce information by using phase conjugate light without requiring the mirror and its driving unit for obtaining the phase conjugate light described in Non-Patent Document 1, and to reduce the recording density. It is an object of the present invention to provide a specific hologram recording medium, reproduction recording apparatus, and reproduction recording method that are suppressed.

  As an example of the above-described purpose, in an optical information recording medium that records and reproduces the information using holography, the signal light and the reference light are not reflected during information recording, and the reference light is used during information reproduction. This is achieved by providing a reflective layer that reflects and generates phase conjugate light.

  According to the present invention, a specific hologram recording that enables reproduction of information by phase conjugate light and suppresses a decrease in recording density without requiring a mirror for obtaining phase conjugate light and its driving unit. A medium, a playback / recording apparatus, and a playback / recording method can be provided.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram showing a recording / reproducing apparatus of an optical information recording medium for recording and / or reproducing digital information using holography.

  The optical information recording / reproducing apparatus 10 includes a pickup 11, a phase conjugate optical system 12, a disk cure optical system 13, a disk rotation angle detection optical system 14, and a rotation motor 50, and the optical information recording medium 1 is a rotation motor 50. It is the structure which can be rotated by.

  The pickup 11 plays a role of emitting reference light and signal light to the optical information recording medium 1 and recording digital information on the recording medium using holography. At this time, the information signal to be recorded is sent by the controller 89 to the spatial light modulator in the pickup 11 via the signal generation circuit 86, and the signal light is modulated by the spatial light modulator.

  When the information recorded on the optical information recording medium 1 is reproduced, the phase conjugate light 12 of the reference light emitted from the pickup 11 is generated by the reflective layer in the optical information recording medium. The phase conjugate light is a light wave that travels in the opposite direction while maintaining the same wavefront as the input light. Reproduction light reproduced by the phase conjugate light is detected by a photodetector described later in the pickup 11, and a signal is reproduced by the signal processing circuit 85. When the signal light passes through the lens, wavefront aberration is generated, and the state of signal light condensing on the disk 1 is deteriorated. However, the quality of the reproduction signal can be improved by using the phase conjugate light as the reproduction light.

  The irradiation time of the reference light and the signal light applied to the optical information recording medium 1 can be adjusted by controlling the opening / closing time of the shutter in the pickup 11 via the shutter control circuit 87 by the controller 89.

  The disk cure optical system 13 plays a role of generating a light beam used for pre-cure and post-cure of the optical information recording medium 1. Precure is a pre-process for irradiating a predetermined light beam in advance before irradiating the desired position with reference light and signal light when recording information at a desired position in the optical information recording medium 1. Post-cure is a post-process for irradiating a predetermined light beam after recording information at a desired position in the optical information recording medium 1 so that additional recording cannot be performed at the desired position.

  The disk rotation angle detection optical system 14 is used to detect the rotation angle of the optical information recording medium 1. When adjusting the optical information recording medium 1 to a predetermined rotation angle, a signal corresponding to the rotation angle is detected by the disk rotation angle detection optical system 14, and a disk rotation motor control circuit is detected by the controller 89 using the detected signal. The rotation angle of the optical information recording medium 1 can be controlled via 88.

  A predetermined light source driving current is supplied from the light source driving circuit 82 to the light sources in the pickup 11, the disk cure optical system 13, and the disk rotation angle detection optical system 14, and each light source emits a light beam with a predetermined light quantity. be able to.

  Further, the pickup 11 and the disk cure optical system 13 are provided with a mechanism capable of sliding the position in the radial direction of the optical information recording medium 1, and position control is performed via the access control circuit 81.

  By the way, since the recording technique using holography is a technique capable of recording ultra-high-density information, for example, an allowable error with respect to the inclination or displacement of the optical information recording medium 1 tends to be extremely small.

  Therefore, a mechanism for detecting the amount of deviation due to a small allowable error, such as tilt or positional deviation of the optical information recording medium 1, is provided in the pickup 11, and the servo signal generation circuit 83 outputs a servo control signal. A servo mechanism for generating and correcting the deviation amount via the servo control circuit 84 may be provided in the optical information recording / reproducing apparatus 10.

  The pickup 11, the disk cure optical system 13, and the disk rotation angle detection optical system 14 may be simplified by combining several optical system configurations or all optical system configurations.

  FIG. 2 shows an example of the optical system configuration of the pickup 11 in the optical information recording / reproducing apparatus 10. The light beam emitted from the light source 301 passes through the collimator lens 302 and enters the shutter 303. When the shutter 303 is open, after the light beam passes through the shutter 303, the optical element 304 composed of, for example, a half-wave plate or the like causes the light quantity ratio of P-polarized light and S-polarized light to become a desired ratio. After the polarization direction is controlled, the light beam enters a PBS (Polarization Beam Splitter) prism 305.

  The light beam transmitted through the PBS prism 305 is expanded by the beam expander 309, and then passes through the phase mask 311, the relay lens 310, and the PBS prism 307 and enters the spatial light modulator 308.

  The signal light beam to which information is added by the spatial light modulator 308 reflects the PBS prism 307 and propagates through the relay lens 312 and the spatial filter 313. Thereafter, the signal light beam is focused on the optical information recording medium 1 by the objective lens 325.

  On the other hand, the light beam reflected from the PBS prism 305 functions as a reference light beam, and is set to a predetermined polarization direction according to recording or reproduction by the polarization direction conversion element 324, and then galvanopathed via the mirror 314 and the mirror 315. Incident on the mirror 316. Since the angle of the galvanometer mirror 316 can be adjusted by the actuator 317, the incident angle of the reference light beam incident on the information recording medium 1 after passing through the lens 319 and the lens 320 can be set to a desired angle.

  In this way, the signal light beam and the reference light beam are incident on the optical information recording medium 1 so as to overlap each other, whereby an interference fringe pattern is formed in the recording medium, and information is written by writing this pattern on the recording medium. Record. In addition, since the incident angle of the reference light beam incident on the optical information recording medium 1 can be changed by the galvanometer mirror 316, recording by angle multiplexing is possible.

  When reproducing the recorded information, the reference light beam is incident on the optical information recording medium 1 as described above, and the light beam transmitted through the optical information recording medium 1 is reflected by the reflection layer in the optical information recording medium. The phase conjugate light is generated.

  The reproduced light beam reproduced by the phase conjugate light propagates through the objective lens 325, the relay lens 312 and the spatial filter 313. Thereafter, the reproduction light beam passes through the PBS prism 307 and enters the photodetector 318, and the recorded signal can be reproduced.

  FIG. 3 shows an operation flow of recording and reproduction in the optical information recording / reproducing apparatus 10. FIG. 3A shows an operation flow from the insertion of the optical information recording medium 1 into the optical information recording / reproducing apparatus 10 until the preparation for recording or reproduction is completed, and FIG. FIG. 3C shows an operation flow until information is recorded on the information recording medium 1, and FIG. 3C shows an operation flow until the information recorded on the optical information recording medium 1 is reproduced from the ready state.

  When a medium is inserted as shown in FIG. 3A, the optical information recording / reproducing apparatus 10 discriminates whether or not the inserted medium is a medium for recording or reproducing digital information using holography, for example.

  As a result of disc discrimination, when it is determined that the optical information recording medium records or reproduces digital information using holography, the optical information recording / reproducing apparatus 10 reads control data provided on the optical information recording medium, for example, Information relating to the optical information recording medium, for example, information relating to various setting conditions during recording and reproduction is acquired.

  After reading out the control data, various adjustments according to the control data and learning processing related to the pickup 11 are performed, and the optical information recording / reproducing apparatus 10 is ready for recording or reproduction.

  As shown in FIG. 3B, the operation flow from the ready state to recording of information first receives data to be recorded, and sends information corresponding to the data to the spatial light modulator in the pickup 11.

  Thereafter, various learning processes are performed in advance so that high-quality information can be recorded on the optical information recording medium, and the positions of the pickup 11 and the disk cure optical system 13 are changed to optical information while repeating seek operation and address reproduction. It is arranged at a predetermined position on the recording medium.

  Thereafter, a predetermined area is pre-cured using a light beam emitted from the disk cure optical system 13, and data is recorded using reference light and signal light emitted from the pickup 11. After the data is recorded, the data is verified as necessary, and post-cure is performed using the light beam emitted from the disk cure optical system 13.

  As shown in FIG. 3C, the operation flow from the ready state to the reproduction of recorded information is performed in advance with various learning processes as necessary so that high-quality information can be reproduced from the optical information recording medium. To do. Thereafter, the pickup 11 is arranged at a predetermined position on the optical information recording medium while repeating the seek operation and the address reproduction. Thereafter, reproduction light is emitted from the pickup 11 to read information recorded on the optical information recording medium.

  FIG. 4 is a diagram showing a layer structure of an optical information recording medium having a reflective layer. (1) shows a state where information is recorded on the optical information recording medium, and (2) shows a state where information is reproduced from the optical information recording medium.

  The optical information recording medium 1 includes a transparent cover layer 400, a recording layer 402, a light absorption / reflection layer 406, and a protective layer 412 from the optical pickup 11 side. The interference pattern between the reference light 4 </ b> A and the signal light 4 </ b> B is recorded on the recording layer 402.

  The light absorption / reflection layer 406 absorbs the reference light 4A and the signal light 4B at the time of information recording, and changes physical properties so as to reflect the reference light at the time of information reproduction. The light absorption / reflection layer 406 is better as the difference in reflectance between reproduction and recording is larger.

  Here, as a characteristic of the material forming the reflective layer, the reflectance during reproduction is required to be 50% or more. The reason for this will be described below.

If the sensitivity of the image sensor is 5 × 10 ⁶ LSB / (J / m ² ) and a resolution of 7 bits or more is required between the On pixel and the Off pixel,
2 ⁷ / (5 × 10 ⁶ × 10 ⁻⁶ ) ≈26 μJ / m ²
Energy is needed. Assuming that the number of pixels of the image sensor is 1024 × 1024, the size of the pixel is 4 μm × 4 μm, and the ratio of the On pixel to the Off pixel is 1: 1, the area irradiated with the light of the image sensor is
(1024 × 4 μm) × (1024 × 4 μm) /2=8.4×10 ⁻⁶ m ²
Therefore, the energy required by the image sensor is 26 × 8.4 × 10 ⁻⁶ ≈0.2 nJ
It becomes. Light source output 80mW, hologram diffraction efficiency 0.1%, irradiation time 0.1
ms, when the efficiency of the optical system before reflection is 5%, the required reflectance is 0.2 × 10 ⁻⁹ / (80 × 10 ⁻³ × 0.001 × 0.1 × 10 ⁻³ × 0. 05) = 50%
It becomes.

  According to the applicant's examination, it has been confirmed that there is no problem if the reflectance during recording is 20% or less.

  The light absorption / reflection layer 406 is formed by sputtering, for example, ITO (indium tin oxide), magnesium-nickel alloy as an electrochromic (EC) material, palladium, and ITO in this order on the surface of a UV resin formed in a diffraction grating shape. Can be configured. Since ITO has conductivity, the coloring / decoloring state of the light absorption / reflection layer 406 is changed by applying a voltage to the EC material using two ITO layers sandwiching the EC material as electrodes. Magnesium-nickel alloy is a hydrogen storage alloy and has the property of absorbing hydrogen well. Usually, this operating temperature is as high as 500 degrees, but due to the catalytic action of palladium, hydrogen is absorbed and released even at room temperature. Reference 1 describes the characteristics of magnesium-nickel alloys as EC materials. Further, as the EC material, a modified material obtained by adding other components to a magnesium-nickel alloy can be used as long as the same effect can be obtained. Further details are described in Non-Patent Document 3, for example.

  At the time of information recording, the light absorption / reflection layer 406 is in a decolored state and absorbs the reference light 4A and the signal light 4B that have passed through the recording layer 402. At the time of information reproduction, the reference light 4A that is in a colored state, reflects the reference light, and reflects the light absorption / reflection layer 406 becomes the phase conjugate light 4C.

  As shown by reference numeral 100 in FIG. 1, the optical information recording / reproducing apparatus is an optical information recording medium as described in Reference 2 as a characteristic changing mechanism for changing the reflection characteristic of the optical information recording medium. What is necessary is just to make it provide the voltage application circuit according to the method of applying a voltage to an electrode layer. That is, an alternating current is applied to the rotor side coil of the spindle motor to generate an induced current in the stator side coil, and a voltage obtained by rectifying the induced current is applied to the electrode layer of the optical information recording medium. . With this configuration, a voltage can be applied in a non-contact manner, so that a stable voltage application is possible. Further details are described in Non-Patent Document 4, for example.

  The light absorption / reflection layer 406 reflects the reference light 4A into the phase conjugate light 4C along the direction in which the reference light 4A is applied to the information recording medium. As shown, a blazed (sawtooth) reflective diffraction insulator is provided.

When the m-order diffracted light of the reference light 4A generated by the reflective diffraction grating is used as the phase conjugate light 4C, the reference light may be incident perpendicularly to the slope of the grating, and the following (1) and ( It is sufficient if 2) holds.
α = θ (1)
α: Angle formed by the reference light and phase conjugate light with respect to the normal of the grating, θ: Angle of the slope of the grating P = (mλ) / (2n × sin α) (2)
P: grating pitch λ: wavelength of reference light n: refractive index of medium surrounding reflection diffraction grating, for example, first order (m = 1) diffracted light with respect to incident light with respect to reference light having an incident angle of 30 degrees If the blazed grating is designed to be diffracted in the opposite direction,
In the case of λ = 0.405 μm, α = 30 °, the slope angle of the lattice θ = α = 30 °, and n = 1.5, the pitch of the lattice (P) = 0.405 / 2 × 1.5 sin 30 ° = 0. .27 μm is sufficient.

  As shown in FIG. 6, the presence / absence of the reflective diffraction grating layer is determined by providing a flag in an area corresponding to BCA (Burst Cutting Area) in the BD standard, for example. Can increase the sex. In addition, by providing information on the reflectance, absorptance, and transmittance at the time of coloring and decoloring of the light absorption / reflection layer in a region corresponding to BCA and using it for determination of the amount of laser light, The convenience of the optical information recording / reproducing apparatus can be improved.

  Further, the information relating to the optical information medium may of course be configured to be readable by a BD reproducing laser in order to ensure compatibility with the current BD drive or the like.

  As described above, according to the optical information recording medium of the present invention, the optical information recording medium includes a reflection layer for generating phase conjugate light of the reference light at the time of reproducing the information. When recording information, the signal light and reference light are not reflected by the reflection layer, and when reproducing information, the reference light is reflected by the reflection layer to obtain phase conjugate light, so that phase conjugate light is obtained. Therefore, information can be reproduced by phase conjugate light without requiring a mirror and its driving unit, and information can be recorded and reproduced without reducing the recording density.

  Furthermore, by configuring the reflective layer to be a blazed reflective diffraction grating as shown in FIG. 5, phase conjugate light traveling in the opposite direction to the reference light can be generated, and recording on an optical information recording medium can be performed. The density can be increased.

  In the above description, the recording medium has been mainly described as a disk, but of course, it may be a card-type medium or other shape medium.

  As another modification, in an optical information recording medium that records information using holography, the optical information recording medium records a recording layer in which an interference pattern generated by signal light and reference light is recorded, and information is recorded. In this case, the optical information recording medium may be provided with a signal light that has passed through the recording layer and a layer that can absorb and / or transmit the reference light as compared with the case of reproducing information.

  As another modification, in an optical information recording medium for recording and reproducing information using holography, the optical information recording medium includes a recording layer in which an interference pattern generated by signal light and reference light is recorded, and information When recording information, the first state in which signal light and reference light that have passed through the recording layer are absorbed and / or transmitted compared to when reproducing information, and when information is reproduced, compared with when information is recorded. In addition, the optical information recording medium may include an optical absorption / reflection layer that can change to the second state in which the reference light is reflected to generate phase conjugate light.

  Further, as another modified example, a reproducing apparatus that reproduces information using holography, the reproducing apparatus can be mounted with a recording medium having layers having different reflectivities according to the amount of voltage applied, A light source that generates reference light, an irradiating unit that irradiates the recording medium with the reference light generated by the light source, a signal processing circuit that processes reproduction light irradiated and reproduced by the irradiating unit, and an amount of voltage applied to the recording medium Control means for controlling the optical information reproducing apparatus for controlling the voltage application amount so as to obtain the phase conjugate light with the recording medium when reproducing the information, or for recording the information. When recording, the interference pattern generated by the signal light and the reference light is recorded on the optical information recording medium, and when reproducing the information, the reference light irradiated on the optical information recording medium is reflected by the reflective layer of the optical information recording medium. The obtained phase An optical information recording / reproducing apparatus for reproducing information using light, a light source that generates signal light and reference light, a spatial light modulator that spatially modulates signal light with the information when recording information, A means for irradiating the recording medium with the signal light modulated by the spatial modulator, and an irradiating means for irradiating the recording medium with the reference light when reproducing information, and processing the reproduction light irradiated and reproduced by the irradiation. And a means for changing the characteristics of the reflective layer of the recording medium. The means for changing the characteristics of the reflective layer of the recording medium is more reflective when recording information than when reproducing information. An optical information recording / reproducing device that changes the characteristics of the reflective layer so that the reflectance is improved in the reflective layer when information is reproduced while suppressing the reflectance in the layer may be used. .

  As another modification, when recording information, an interference pattern generated by the signal light and the reference light is recorded on the optical information recording medium, and when reproducing the information, the reference light irradiated on the optical information recording medium is recorded. Is a method of reproducing information using phase conjugate light obtained by reflecting on a reflective layer of the optical information recording medium, wherein signal information and reference light are generated and information is recorded when the information light is recorded. The signal light is spatially modulated with information, the modulated signal light is irradiated onto the recording medium together with the reference light, and when reproducing the information, the reference light is irradiated onto the recording medium, and the reproduction is performed by irradiating the reference light. When processing light and recording information, the reflectance is suppressed by the reflective layer compared to when reproducing information, and when reproducing information, the reflectance is improved by the reflective layer compared with when recording information. With optical information recording and playback method It may be.

It is a block diagram concerning embodiment of an optical information recording / reproducing apparatus. It is a figure which shows the structure of embodiment of the pickup in an optical information recording / reproducing apparatus. It is a block diagram which shows embodiment of the operation | movement flow of an optical information recording / reproducing apparatus. It is a figure which shows the layer structure concerning embodiment of an optical information recording medium. It is a figure which expands and shows the interface shape of the light reflection layer of the optical information recording medium concerning FIG. It is a figure which shows the structure which gives the information of a light absorption / reflection layer to a BCA area | region.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical information recording medium 10 Optical information recording / reproducing apparatus 11 Pickup 12 Phase conjugate optical system 13 Disc Cure optical system 14 Disc rotation angle detection optical system 50 Rotating motor 81 Access control circuit 82 Light source drive circuit 83 Servo signal generation circuit 84 Servo control Circuit 85 Signal processing circuit 86 Signal generation circuit 87 Shutter control circuit 88 Disc rotation motor control circuit 89 Controller 100 Characteristic change mechanism 301 Light source 302 Collimator lens 303 Shutter 304 Optical element 305 Polarization beam splitter 306 Signal light 307 Polarization beam splitter 308 Spatial light modulation 309 Beam expander 310 Relay lens 311 Phase mask 312 Relay lens 313 Spatial filter 314 Mirror 315 Mirror 316 Galvano mirror 317 Actuator 318 Photodetector 319 Lens 320 Lens 324 Polarization direction conversion element 325 Objective lens 400 Transparent cover layer 402 Recording layer 406 Light absorption / reflection layer 412 Protective layer

Claims (18)

In an optical information recording medium for recording and reproducing information using holography,
The optical information recording medium includes a recording layer on which an interference pattern generated by signal light and reference light is recorded;
When recording information, a first state in which the signal light and the reference light that have passed through the recording layer are absorbed; and when reproducing information, a second state in which the reference light is reflected to generate phase conjugate light. A light absorbing / reflecting layer that can reversibly change between states;
An optical information recording medium comprising:   2. The optical information recording medium according to claim 1, wherein the light absorption / reflection layer is made of an electrochromic material whose reflectance varies depending on whether or not a voltage is applied.   The optical information recording medium according to claim 2, wherein the light absorption / reflection layer has a diffraction grating shape.   4. The optical information recording medium according to claim 3, wherein the light absorbing / reflecting layer is formed by forming an electrochromic layer on a UV resin formed in a diffraction grating shape.   4. The optical information recording medium according to claim 3, wherein the diffraction grating of the light absorption / reflection layer has a blazed shape.   The optical information recording medium according to claim 2, wherein the electrochromic material constituting the light absorption / reflection layer is a magnesium-nickel alloy.   2. The optical information recording medium according to claim 1, wherein the reflectance of the light absorption / reflection layer at the time of information reproduction is 50% or more. In an optical information recording medium that records information using holography,
The optical information recording medium includes a recording layer on which an interference pattern generated by signal light and reference light is recorded;
When recording information, a layer capable of absorbing and / or transmitting the signal light and the reference light that has passed through the recording layer, compared to reproducing information,
An optical information recording medium comprising: When recording the information, the layer capable of absorbing and / or transmitting the signal light and the reference light that has passed through the recording layer is more suitable for the amount of voltage applied than when information is reproduced. Consists of electrochromic materials with varying reflectivity,
The optical information recording medium according to claim 8. When recording the information, the layer capable of absorbing and / or transmitting the signal light and the reference light that has passed through the recording layer is in the shape of a diffraction grating compared to when reproducing the information. ,
The optical information recording medium according to claim 9. When recording the information, the layer capable of absorbing and / or transmitting the signal light and the reference light that has passed through the recording layer is formed in a diffraction grating shape compared to when reproducing the information. Constructed by forming an electrochromic layer on a UV resin.
The optical information recording medium according to claim 9. When recording the information, the layer capable of absorbing and / or transmitting the signal light and the reference light that has passed through the recording layer is a blazed diffraction grating as compared to when reproducing the information. ,
The optical information recording medium according to claim 10. When recording the information, the electrochromic material constituting the layer capable of absorbing and / or transmitting the signal light and the reference light that has passed through the recording layer, compared to when reproducing the information, is magnesium.・ Nickel alloy
The optical information recording medium according to claim 9. When recording the information, the layer capable of absorbing and / or transmitting the signal light and the reference light that has passed through the recording layer has a reflectance during recording as compared to when reproducing the information. 20% or less,
The optical information recording medium according to claim 8. In an optical information recording medium for recording and reproducing information using holography,
The optical information recording medium includes a recording layer on which an interference pattern generated by signal light and reference light is recorded;
When recording information, the first state in which the signal light and the reference light that have passed through the recording layer are absorbed and / or transmitted compared to when information is reproduced, and when information is reproduced, information is recorded. A light absorption / reflection layer that is changeable to a second state in which the reference light is reflected to generate phase conjugate light, as compared to
An optical information recording medium comprising: A reproducing apparatus that reproduces information using a holography, wherein the reproducing apparatus can mount a recording medium having layers having different reflectivities according to the amount of voltage applied,
A light source for generating reference light;
Irradiating means for irradiating the recording medium with reference light generated by the light source;
A signal processing circuit for processing reproduced light irradiated and reproduced by the irradiation means;
Control means for controlling the amount of voltage applied to the recording medium;
With
The control means controls the voltage application amount so as to obtain phase conjugate light on the recording medium when reproducing information,
Optical information reproducing device. When recording information, an interference pattern generated by the signal light and the reference light is recorded on the optical information recording medium, and when reproducing the information, the reference light applied to the optical information recording medium is used as a reflection layer of the optical information recording medium. An optical information recording / reproducing apparatus for reproducing information using phase conjugate light obtained by reflection at
A light source for generating signal light and reference light;
When recording information, a spatial light modulator that spatially modulates the signal light with the information; and
Means for irradiating the recording medium together with the reference light with the signal light modulated by the spatial modulator;
When reproducing information, an irradiating means for irradiating a recording medium with a reference beam;
A signal processing circuit for processing reproduced light irradiated and reproduced by the irradiation;
Means for changing the characteristics of the reflective layer of the recording medium;
With
The means for changing the characteristics of the reflective layer of the recording medium suppresses the reflectance in the reflective layer when recording information, and records information when reproducing information. In comparison, the characteristics of the reflective layer are changed so as to improve the reflectance of the reflective layer.
Optical information recording / reproducing apparatus. When recording information, an interference pattern generated by the signal light and the reference light is recorded on the optical information recording medium, and when reproducing the information, the reference light applied to the optical information recording medium is used as a reflection layer of the optical information recording medium. An optical information recording / reproducing method for reproducing information using phase conjugate light obtained by reflection at
Generate signal light and reference light,
When recording information, the signal light is spatially modulated with the information,
Irradiating the recording medium with the modulated signal light together with a reference light;
When reproducing information, the recording medium is irradiated with a reference beam,
Processing the reproduction light that has been irradiated and reproduced by the reference light,
When recording information, the reflectance is suppressed by the reflective layer, compared to when reproducing information,
When reproducing information, the reflective layer improves the reflectance compared to recording information,
Optical information recording / reproducing method.

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