JP2016071918A - Optical information recording / reproducing apparatus and optical information reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To block unnecessary light in reproduction in an optical information recording and reproducing device for performing reproduction on an optical information recording medium where an interference pattern between signal light in which information is redundant and reference light is recorded as a hologram by a phase conjugation system.SOLUTION: The optical information recording and reproducing device includes a light source which emits a light beam, a spatial light modulator 312 for adding two-dimensional information to the signal light, a photodetector 325 which receives diffraction light obtained by irradiating the optical information recording medium with the light beam, and a reflection light blocking part 326 which prevents a part of the diffraction light from being reflected to the spatial light modulator 312 and entering a light detection part. The reflection light blocking part 326 includes a light blocking member which is arranged in front of the incident surface of the spatial light modulator 312.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an apparatus and method for reproducing information from a recording medium using holography.

  As a background art, for example, there is a technique described in Patent Document 1.

JP 2005-285262 A

  Currently, the Blu-ray Disc (TM) 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 disks to the same level as the HDD (Hard Disk 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.

  The 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 hologram recording medium, and an interference fringe pattern generated at that time causes the recording light to be recorded in the recording medium. This is a technique for recording information on a recording medium by generating 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. The diffracted light is reproduced as the same light including the recorded signal light and phase information, and 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.

  In an optical information recording / reproducing apparatus that records digital information using holography, a diffracted light obtained by irradiating a hologram recording medium with reference light is incident on a photodetector to reproduce information. When unnecessary light is incident on the digital signal, the S / N of the digital information deteriorates and a data error occurs.

  As a technique for shielding unnecessary light incident upon reproduction, Patent Document 1 discloses that “a shutter 24 closed in the reproduction mode is arranged between the signal light optical system 21 and the hologram recording medium 23. The illumination reference light 200 is irradiated onto the hologram recording medium 23 and a part thereof is reflected. However, since the reflected light 201 is blocked by the shutter 24 and is not incident on the signal light optical system 21, it is folded back from the signal light optical system 21. Thus, it returns to the hologram recording medium 23. Thereby, only the diffracted light 300 generated by the hologram recording medium 23 is incident on the imaging device 25 through the reproducing light optical system 22.

  The optical information recording / reproducing apparatus described in Patent Document 1 includes a signal light optical system, a reference light optical system, and a reproduction light optical system. At the time of recording, the interference fringes are recorded by superimposing each light passing through the signal light optical system and the reference light optical system on the hologram recording medium. During reproduction, the diffracted light generated by irradiating the recording medium with the reference light that has passed through the reference light optical system passes through the reproducing light optical system and enters the photodetector, so that the unused signal light optical system and the recording medium A shutter can be placed between them to shield the light. However, since this configuration realizes recording / reproduction with three types of optical systems, it is disadvantageous in reducing the size of the optical information recording / reproducing apparatus.

  Here, as an optical information recording / reproducing apparatus that is advantageous for downsizing, there is a system that is constituted by two types of signal light optical system and reference light optical system and performs reproduction by phase conjugation. On the other hand, since both the signal light optical system and the reference light optical system are used during reproduction, it is impossible to shield the light by arranging a shutter or the like between the recording medium and the signal light optical system.

  In view of the above, an object of the present invention is to block unnecessary light during reproduction in a phase conjugate optical information recording / reproducing apparatus advantageous for downsizing.

    In order to solve the above-described problems, the present invention uses configurations described in the claims as an example.

More specifically, the optical information recording / reproducing apparatus according to the present invention reproduces information on an optical information recording medium in which an interference pattern between signal light with redundant information and reference light is recorded as a hologram by a phase conjugate method. In the optical information recording / reproducing apparatus, a light source that emits a light beam, an optical element that separates the light beam into signal light and reference light,
A spatial light modulator for adding two-dimensional information to the signal light, a photodetector for receiving diffracted light obtained by irradiating the optical information recording medium with the reference light, and a part of the diffracted light. A reflected light shielding unit that reflects the spatial light modulator and prevents the reflected light from entering the light detection unit, and the reflected light shielding unit includes a light shielding member in front of the incident surface of the spatial light modulator. Have.

  According to the present invention, it is possible to prevent S / N deterioration due to unnecessary light with respect to reproduced digital information in a phase conjugation method advantageous for miniaturization.

Schematic of a pickup configuration that blocks unnecessary light during reproduction in the first embodiment Schematic diagram showing an embodiment of an optical information recording / reproducing apparatus Schematic showing an embodiment of a pickup in an optical information recording / reproducing apparatus Schematic showing an embodiment of a pickup in an optical information recording / reproducing apparatus Schematic showing an embodiment of the operation flow of the optical information recording / reproducing apparatus Schematic showing an embodiment of the operation flow of the optical information recording / reproducing apparatus Schematic showing an embodiment of the operation flow of the optical information recording / reproducing apparatus Schematic showing the Example of the signal generation circuit in an optical information recording / reproducing apparatus Schematic showing the Example of the signal processing circuit in an optical information recording / reproducing apparatus Schematic showing the Example of the operation | movement flow of a signal generation circuit and a signal processing circuit Schematic showing the Example of the operation | movement flow of a signal generation circuit and a signal processing circuit Schematic diagram of a pickup configuration that blocks unwanted light during playback Schematic explaining the factors that cause unnecessary light during playback Schematic explaining the factors that cause unnecessary light during playback Schematic explaining the factors that cause unnecessary light during playback Schematic diagram of a pickup configuration that blocks unwanted light during playback Schematic showing a moving mechanism that moves the light shielding member Schematic showing a shutter mechanism that moves a light shielding member Schematic showing an embodiment of the operation flow of the optical information recording / reproducing apparatus Schematic showing an embodiment of the operation flow of the optical information recording / reproducing apparatus Schematic of a pickup configuration that blocks unnecessary light during reproduction in the second embodiment Schematic of a pickup configuration that blocks unnecessary light during reproduction in the second embodiment Schematic showing an embodiment of the operation flow of the optical information recording / reproducing apparatus Schematic showing an embodiment of the operation flow of the optical information recording / reproducing apparatus

  Hereinafter, although the form for implementing this invention is demonstrated based on the Example shown in a figure, this invention is not limited by this.

  Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 2 is a block diagram showing a recording / reproducing apparatus for an optical information recording medium for recording and reproducing digital information using holography.

  The optical information recording / reproducing device 10 is connected to an external control device 91 via an input / output control circuit 90. In the case of recording, the optical information recording / reproducing apparatus 10 receives the information signal to be recorded from the external control device 91 by the input / output control circuit 90. When reproducing, the optical information recording / reproducing apparatus 10 transmits the reproduced information signal to the external control apparatus 91 by the input / output control circuit 90.

  The optical information recording / reproducing apparatus 10 includes a pickup 11, a reproduction reference light optical system 12, a cure optical system 13, a disk rotation angle detection optical system 14, and a rotation motor 50. The optical information recording medium 1 is a rotation motor. 50 can be rotated.

  The pickup 11 plays the role of irradiating the optical information recording medium 1 with reference light and signal light 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 reproducing the information recorded on the optical information recording medium 1, the reproduction reference light optical system 12 generates a light wave that causes the reference light emitted from the pickup 11 to enter the optical information recording medium in a direction opposite to that during recording. Generate. Reproduction light reproduced by the reproduction reference light is detected by a photodetector (to be described later) in the pickup 11, and a signal is reproduced by the signal processing circuit 85. The light shielding control circuit 92 controls a mechanism for shielding unnecessary light other than the reproduction light detected by the photodetector described later during reproduction.

  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 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 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 amount. Can do.

  Further, the pickup 11 and the disc 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, the recording technique using the principle of angle multiplexing of holography tends to have a very small tolerance for the deviation of the reference beam angle.

  Therefore, a mechanism for detecting the deviation amount of the reference beam angle is provided in the pickup 11, a servo control signal is generated by the servo signal generation circuit 83, and the deviation amount is corrected via the servo control circuit 84. It is necessary to provide a servo mechanism for this purpose in the optical information recording / reproducing apparatus 10.

  Further, the pickup 11, the 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. 3 shows a recording principle in an example of a basic 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 ratio of the p-polarized light and the s-polarized light becomes a desired ratio by the optical element 304 composed of, for example, a half-wave plate. After the polarization direction is controlled, the light beam enters a PBS (Polarization Beam Splitter) prism 305.

  The light beam that has passed through the PBS prism 305 functions as signal light 306, and after the light beam diameter is expanded by the beam expander 308, the light beam passes through the phase mask 309, the relay lens 310, and the PBS prism 311 and passes through the spatial light modulator 312. Is incident on.

  The signal light to which information is added by the spatial light modulator 312 reflects the PBS prism 311 and propagates through the relay lens 313 and the spatial filter 314. Thereafter, the signal light is condensed on the optical information recording medium 1 by the objective lens 315.

  On the other hand, the light beam reflected from the PBS prism 305 functions as reference light 307 and is set to a predetermined polarization direction according to recording or reproduction by the polarization direction conversion element 316 and then galvano- lated via the mirror 317 and the mirror 318. Incident on the mirror 319. Since the angle of the galvanometer mirror 319 can be adjusted by the actuator 320, the incident angle of the reference light incident on the optical information recording medium 1 after passing through the lens 321 and the lens 322 can be set to a desired angle. In order to set the incident angle of the reference light, an element that converts the wavefront of the reference light may be used instead of the galvanometer mirror.

  In this way, the signal light and the reference light 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 recorded by writing this pattern on the recording medium. To do. In addition, since the incident angle of the reference light incident on the optical information recording medium 1 can be changed by the galvanometer mirror 319, recording by angle multiplexing is possible.

  Hereinafter, in holograms recorded in the same area with different reference beam angles, holograms corresponding to each reference beam angle are called pages, and a set of pages angle-multiplexed in the same area is called a book. .

  FIG. 4 shows the principle of phase conjugate reproduction in an example of the basic optical system configuration of the pickup 11 in the optical information recording / reproducing apparatus 10. When reproducing the recorded information, the reference light 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 galvanometer mirror 324 whose angle can be adjusted by the actuator 323. By doing so, the reproduction reference light is generated.

  The reproduction light reproduced by the reproduction reference light propagates through the objective lens 315, the relay lens 313, and the spatial filter 314. Thereafter, the reproduction light passes through the PBS prism 311 and enters the photodetector 325, and the recorded signal can be reproduced. As the photodetector 325, for example, an image sensor such as a CMOS image sensor or a CCD image sensor can be used. However, any element may be used as long as page data can be reproduced.

  FIGS. 5 a and bc show an operation flow of recording and reproduction in the optical information recording / reproducing apparatus 10. Here, a flow relating to recording / reproduction using holography in particular will be described.

  FIG. 5a shows an operation flow from when the optical information recording medium 1 is inserted into the optical information recording / reproducing apparatus 10 until preparation for recording or reproduction is completed. FIG. 5b shows information from the ready state to the optical information recording medium 1. FIG. 5 c 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. 5a (601), the optical information recording / reproducing apparatus 10 discriminates whether the inserted medium is a medium for recording or reproducing digital information using holography, for example (see FIG. 5a). 602).

  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 (603). ), For example, information relating to the optical information recording medium and information relating to various setting conditions during recording and reproduction, for example.

  After reading out the control data, various adjustments according to the control data and learning processing (604) related to the pickup 11 are performed, and the optical information recording / reproducing apparatus 10 is ready for recording or reproduction (605).

  As shown in FIG. 5b, the operation flow from the ready state to recording of information first receives data to be recorded (611), and sends information corresponding to the data to the spatial light modulator in the pickup 11.

  Thereafter, various recording learning processes such as optimization of the power of the light source 301 and optimization of exposure time by the shutter 303 are performed in advance so that high-quality information can be recorded on the optical information recording medium (612). ).

  Thereafter, in the seek operation (613), the access control circuit 81 is controlled to position the pickup 11 and the cure optical system 13 at predetermined positions on the optical information recording medium. When the optical information recording medium 1 has address information, it reproduces the address information, checks whether it is positioned at the target position, and calculates the amount of deviation from the predetermined position if it is not positioned at the target position. And repeat the positioning operation.

  Thereafter, a predetermined region is pre-cured using the light beam emitted from the cure optical system 13 (614), and data is recorded using the reference light and signal light emitted from the pickup 11 (615).

  After recording the data, post-cure is performed using the light beam emitted from the cure optical system 13 (616). Data may be verified as necessary.

  As shown in FIG. 5c, the operation flow from the ready state to the reproduction of recorded information is as follows. First, in the seek operation (621), the access control circuit 81 is controlled to pick up the pickup 11 and the reproduction reference light optical system 12. Is positioned at a predetermined position on the optical information recording medium. When the optical information recording medium 1 has address information, it reproduces the address information, checks whether it is positioned at the target position, and calculates the amount of deviation from the predetermined position if it is not positioned at the target position. And repeat the positioning operation.

  Thereafter, reference light is emitted from the pickup 11, information recorded on the optical information recording medium is read (622), and reproduction data is transmitted (623).

  FIGS. 8A and 8B show a data processing flow at the time of recording and reproduction. FIG. 8A shows the input / output control circuit 90 after the recording data receiving process 611 and then converting it into two-dimensional data on the spatial light modulator 312. FIG. 8B shows the recording data processing flow in the signal generation circuit 86 until the signal processing circuit 85 until the reproduction data transmission processing 624 in the input / output control circuit 90 after the two-dimensional data is detected by the photodetector 325. The reproduction data processing flow in FIG.

  Data processing during recording will be described with reference to FIG. 8a. When user data is received (901), it is divided into a plurality of data strings, and each data string is converted to CRC (902) so that error detection at the time of reproduction can be performed. In order to prevent repetition, the data string is scrambled (903) to add a pseudo-random data sequence, and then error correction coding (904) such as Reed-Solomon code is performed so that error correction at the time of reproduction can be performed. Next, the data string is converted into M × N two-dimensional data, and the two-dimensional data (905) for one page is configured by repeating the data for one page data. A marker serving as a reference for image position detection and image distortion correction at the time of reproduction is added to the two-dimensional data thus configured (906), and the data is transferred to the spatial light modulator 312 (907).

  Next, a data processing flow during reproduction will be described with reference to FIG. The image data detected by the photodetector 325 is transferred to the signal processing circuit 85 (911). Image position is detected based on the marker included in the image data (912), distortion such as image tilt, magnification, distortion, etc. is corrected (913), and then binarization processing (914) is performed to remove the marker. (915) to acquire (916) two-dimensional data for one page. After converting the two-dimensional data obtained in this way into a plurality of data strings, error correction processing (917) is performed to remove the parity data strings. Next, descrambling processing (918) is performed, CRC error detection processing (919) is performed and CRC parity is deleted, and then user data is transmitted (920) via the input / output control circuit 90.

  FIG. 6 is a block diagram of the signal generation circuit 86 of the optical information recording / reproducing apparatus 10.

  When the input of user data is started to the output control circuit 90, the input / output control circuit 90 notifies the controller 89 that the input of user data has started. In response to this notification, the controller 89 instructs the signal generation circuit 86 to record data for one page input from the input / output control circuit 90. A processing command from the controller 89 is notified to the sub-controller 701 in the signal generation circuit 86 via the control line 708. Upon receiving this notification, the sub-controller 701 controls each signal processing circuit via the control line 708 so that the signal processing circuits are operated in parallel. First, the memory control circuit 703 is controlled to store user data input from the input / output control circuit 90 via the data line 709 in the memory 702. When the user data stored in the memory 702 reaches a certain amount, the CRC calculation circuit 704 performs control to convert the user data into CRC. Next, the scramble circuit 705 scrambles the CRC-converted data to add a pseudo-random data sequence, and the error correction encoding circuit 706 performs error correction encoding to add the parity data sequence. Finally, the pickup interface circuit 707 reads out the error correction encoded data from the memory 702 in the order of the two-dimensional data on the spatial light modulator 312 and adds a reference marker at the time of reproduction. The two-dimensional data is transferred to the spatial light modulator 312.

  FIG. 7 is a block diagram of the signal processing circuit 85 of the optical information recording / reproducing apparatus 10.

  When the photodetector 325 in the pickup 11 detects the image data, the controller 89 instructs the signal processing circuit 85 to reproduce the data for one page input from the pickup 11. A processing command from the controller 89 is notified to the sub-controller 801 in the signal processing circuit 85 via the control line 811. Upon receiving this notification, the sub-controller 801 controls each signal processing circuit via the control line 811 so that the signal processing circuits are operated in parallel. First, the memory control circuit 803 is controlled to store the image data input from the pickup 11 via the pickup interface circuit 810 via the data line 812 in the memory 802. When the data stored in the memory 802 reaches a certain amount, the image position detection circuit 809 performs control to detect a marker from the image data stored in the memory 802 and extract an effective data range. Next, the image distortion correction circuit 808 performs distortion correction such as image inclination, magnification, and distortion by using the detected marker, and controls to convert the image data into the expected two-dimensional data size. Each bit data of a plurality of bits constituting the size-converted two-dimensional data is binarized by the binarization circuit 807 to determine “0” or “1”, and the data is arranged on the memory 802 in the order of the output of the reproduction data. Control to store. Next, the error correction circuit 806 corrects an error included in each data string, and the scramble release circuit 805 releases the scramble to add the pseudo random number data string. Check not included. Thereafter, user data is transferred from the memory 802 to the input / output control circuit 90.

  FIG. 9 shows an example of the optical system configuration of the pickup 11 in the optical information recording / reproducing apparatus 9 for blocking unnecessary light during reproduction of a recorded hologram. The basic configuration is the same as the optical system configuration shown in FIG. 4 except that a light shielding member 326 is arranged in front of the incident surface of the spatial light modulator 312. Since the light shielding member 326 is intended to shield light, a light absorbing material is used.

  When reproducing the recorded information, the reference beam is incident on the optical information recording medium 1 and the light beam transmitted through the optical information recording medium 1 is reflected by the galvanometer mirror 324 whose angle can be adjusted by the actuator 323. The reference light for reproduction is generated. The reproduction light reproduced by the reproduction reference light propagates through the objective lens 315, the relay lens 313, and the spatial filter 314. Thereafter, the reproduction light passes through the PBS prism 311 and enters the photodetector 325, and the recorded signal can be reproduced.

  FIGS. 10A, 10B, and 10C are schematic diagrams showing the reproduction light in the vicinity of the PBS prism 311 for explaining the factors that cause unnecessary light during reproduction. Here, when the reproduction light is incident on the PBS prism 311, the reflected light is reflected and incident on the spatial light modulator 312 in addition to the transmitted light (p) that is transmitted and incident on the photodetector 325 as shown in FIG. (Q) occurs. The light reflected by the PBS prism 311 and obtained by the spatial light modulator 312 is reflected by the spatial light modulator 312 and again enters the PBS prism 311 as shown in FIG. Then, the light incident on the PBS prism is separated into transmitted light (x) and reflected light (y) as shown in FIG. 10c, but a part of the reflected light (y) is reflected by the end face of the PBS prism 311. Unnecessary light (z) incident on the photodetector 325 is generated. The unnecessary light (z) becomes a small amount of light with respect to the transmitted light (p) due to the separation by the PBS prism 311 or the influence of reflection at the end face. However, as described in Patent Document 1, when the optical information recording medium 1 is irradiated with the reference light, some of the light reflected by the surface of the optical information recording medium 1 is reflected by the objective lens 315, the relay lens 313, and the like. It propagates through the spatial filter 314 and enters the PBS prism 311. Since the light amount of a part of the light reflected on the surface of the optical information recording medium 1 is larger than the light amount of the reproduced light of the reproduced hologram (for example, about 1000 times), it becomes unnecessary light (z). The light amount is sufficiently detected by the photodetector 325.

  FIG. 1 is a diagram for explaining in detail the reproduction light in the vicinity of the PBS prism 311 during reproduction when the light shielding member 326 is arranged in front of the incident surface of the spatial light modulator 312. When the reproduction light enters the PBS prism 311, transmitted light (p) that is transmitted and incident on the photodetector 325 enters the photodetector 325. However, since the reflected light (q) that has been reflected is shielded by the light shielding member 326, the above-described unnecessary light (z) does not occur.

  In the phase-conjugate optical information recording / reproducing apparatus 10, the influence of the reference light being irradiated onto the optical information recording medium 1 and a part of the light reflected by the surface of the optical information recording medium 1 entering the photodetector is removed. However, it is advantageous for miniaturization because it is composed of two types of signal light optical system and reference light optical system. Furthermore, according to the configuration of the optical information recording / reproducing apparatus 10 that blocks unnecessary light according to the present embodiment, S / N deterioration due to other unnecessary light can be prevented.

  FIG. 11 shows an example of the optical system configuration of the pickup 11 in the optical information recording apparatus 10 during recording. In recording, in order to record the interference pattern between the signal light to which the information is added by the spatial light modulator 312 and the reference light on the optical information recording medium 1 as a hologram, it is installed in front of the incident surface of the spatial light modulator 312. It is necessary to release the light shielding by the light shielding member 326. A moving mechanism 327 shown in FIG. 12a or a shutter mechanism 328 shown in FIG. The moving mechanism 327 shown in FIG. 12a uses a stepping motor to move the light shielding member 326 to the open position (i) or the light shielding position (ii). In the shutter mechanism 328 shown in FIG. 12B, the light shielding member 326 is moved to the open position (i) or the light shielding position (ii) by being rotated by a galvano motor.

  In the present embodiment, a method using a stepping motor or a galvano motor is described as an example of a mechanism for moving the light shielding member, but the present embodiment is not limited to this. For example, movement control can be performed using a linear actuator, and shutters having different shapes may be used.

  FIG. 13 shows an operation flow of recording and reproduction when the light shielding member 326 is arranged in front of the incident surface of the spatial light modulator 312. 13A shows an operation flow until information is recorded on the optical information recording medium 1, and FIG. 13B shows an operation flow until information recorded on the optical information recording medium 1 is reproduced.

  As shown in FIG. 13A, the operation flow until recording information on the optical information recording medium 1 is as follows. First, data to be recorded is received (611), and information corresponding to the data is received from the spatial light modulator 312 in the pickup 11. Send to.

  Thereafter, various recording learning processes such as power optimization of the light source 301 and exposure time optimization by the shutter 303 are performed in advance so that high-quality information can be recorded on the optical information recording medium 1 (see FIG. 612).

  Thereafter, in the seek operation (613), the access control circuit 81 is controlled to position the pickup 11 and the cure optical system 13 at predetermined positions on the optical information recording medium 1. When the optical information recording medium 1 has address information, it reproduces the address information, checks whether it is positioned at the target position, and calculates the amount of deviation from the predetermined position if it is not positioned at the target position. And repeat the positioning operation.

  Here, it is moved to the open position (i) shown in FIG. 13a or 13b by the shading control circuit 92, and enables the incidence of signal light and the addition of information to the spatial light modulator 312 (624).

  Thereafter, a predetermined region is pre-cured using the light beam emitted from the cure optical system 13 (614), and data is recorded using the reference light and signal light emitted from the pickup 11 (615).

  After recording the data, post-cure is performed using the light beam emitted from the cure optical system 13 (616). Data may be verified as necessary.

  The operation flow until the recorded information is reproduced is as shown in FIG. 13b. First, in the seek operation (621), the access control circuit 81 is controlled so that the positions of the pickup 11 and the reproduction reference light optical system 12 are changed. It is positioned at a predetermined position on the information recording medium. When the optical information recording medium 1 has address information, it reproduces the address information, checks whether it is positioned at the target position, and calculates the amount of deviation from the predetermined position if it is not positioned at the target position. And repeat the positioning operation.

  Here, the light-shielding control circuit 92 moves to the light-shielding position (ii) shown in FIG. 13a or 13b to prevent the generation of unnecessary light (625).

  Thereafter, reference light is emitted from the pickup 11, information recorded on the optical information recording medium is read (622), and reproduction data is transmitted (623).

  In this embodiment, unnecessary light is prevented from being generated by moving the light shielding member 326 arranged in front of the incident surface of the spatial light modulator 312 to the light shielding position (ii). However, by tilting the light shielding member 326, PBS It is also possible to control so that the light does not enter the prism 311, and similarly, generation of unnecessary light can be prevented.

  A second embodiment of the present invention will be described with reference to the accompanying drawings. The configuration of the optical information recording / reproducing apparatus 10 in this embodiment (FIG. 2) and the principle of recording and reproduction (FIGS. 3 and 4) are the same as those in the first embodiment, and a description thereof will be omitted.

  The difference from the optical system configuration of the pickup 11 in the optical information recording / reproducing apparatus 10 for blocking unnecessary light at the time of reproducing the recorded hologram in the first embodiment is that light is blocked before the incident surface of the spatial light modulator 312. The point is that unnecessary light is prevented from being generated by moving the spatial light modulator 312 without arranging the member 326.

  FIG. 14a is a diagram for explaining in detail the reproduction light near the PBS prism 311 during reproduction when the spatial light modulator 312 is moved to prevent generation of unnecessary light. Here, when the reproduction light is incident on the PBS prism 311, reflected light (q) is generated in a direction in which the reproduction light is reflected and incident on the spatial light modulator 312 except for the transmitted light (p) that is transmitted and incident on the photodetector 325. . However, since the spatial light modulator 312 is in a position where the reflected light (q) is not incident, and the reflected light (q) does not return to the PBS prism 311, generation of unnecessary light can be prevented.

  FIG. 15 shows an operation flow of recording and reproduction when moving the spatial light modulator 312. FIG. 15A shows an operation flow until information is recorded on the optical information recording medium 1, and FIG. 15B shows an operation flow until information recorded on the optical information recording medium 1 is reproduced.

  As shown in FIG. 15a, the operation flow until information is recorded on the optical information recording medium 1 is first received data to be recorded (611), and information corresponding to the data is received from the spatial light modulator 312 in the pickup 11. Send to.

  Thereafter, various recording learning processes such as power optimization of the light source 301 and exposure time optimization by the shutter 303 are performed in advance so that high-quality information can be recorded on the optical information recording medium 1 (see FIG. 612).

  Thereafter, in the seek operation (613), the access control circuit 81 is controlled to position the pickup 11 and the cure optical system 13 at predetermined positions on the optical information recording medium 1. When the optical information recording medium 1 has address information, it reproduces the address information, checks whether it is positioned at the target position, and calculates the amount of deviation from the predetermined position if it is not positioned at the target position. And repeat the positioning operation.

  Here, the spatial light modulator 312 is moved to a position where the light shown in FIG. 14B is incident by the light shielding control circuit 92, and generates signal light to which information is added. (626).

  Thereafter, a predetermined region is pre-cured using the light beam emitted from the cure optical system 13 (614), and data is recorded using the reference light and signal light emitted from the pickup 11 (615).

  After recording the data, post-cure is performed using the light beam emitted from the cure optical system 13 (616). Data may be verified as necessary.

  The operation flow until the recorded information is reproduced is as shown in FIG. 15b. First, in the seek operation (621), the access control circuit 81 is controlled so that the positions of the pickup 11 and the reproduction reference light optical system 12 are changed. It is positioned at a predetermined position on the information recording medium. When the optical information recording medium 1 has address information, it reproduces the address information, checks whether it is positioned at the target position, and calculates the amount of deviation from the predetermined position if it is not positioned at the target position. And repeat the positioning operation.

  Here, the spatial light modulator 312 is moved to a position where the reflected light (q) shown in FIG. 14a is not incident by the light blocking control circuit 92, thereby preventing unnecessary light from being generated (625).

  Thereafter, reference light is emitted from the pickup 11, information recorded on the optical information recording medium is read (622), and reproduction data is transmitted (623).

  Although the generation of unnecessary light is prevented by moving the spatial light modulator 312 to a position where the reflected light (q) is not incident, the spatial light modulator 312 is controlled so as not to be reflected by the PBS prism 311. Similarly, generation of unnecessary light can be prevented.

  According to the configuration of the optical information recording / reproducing apparatus 10 that blocks unnecessary light according to the present invention, the S / N deterioration due to unnecessary light can be prevented in the phase conjugate optical information recording / reproducing apparatus 10 that is advantageous for downsizing. .

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs, tables, and files for realizing each function can be stored in a memory, a hard disk, a recording device such as an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

  Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

DESCRIPTION OF SYMBOLS 1 ... Optical information recording medium, 10 ... Optical information recording / reproducing apparatus, 11 ... Pickup,
12 ... Reference light optical system for reproduction, 13 ... Disc Cure optical system,
14 ... Optical system for detecting disk rotation angle, 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, 90 ... Input / output control circuit, 91 ... External control device,
92: light shielding control circuit 301: light source, 303: shutter, 306: signal light, 307: reference light,
308 ... Beam expander, 309 ... Phase mask
310 ... relay lens, 311 ... PBS prism,
312 ... Spatial light modulator, 313 ... Relay lens, 314 ... Spatial filter,
315 ... objective lens, 316 ... polarization direction conversion element, 320 ... actuator,
321 ... lens, 322 ... lens, 323 ... actuator,
324 ... Mirror, 325 ... Photodetector, 326 ... Shading member 327 ... Moving mechanism, 328 ... Shutter mechanism

Claims (10)

In an optical information recording / reproducing apparatus for reproducing information in an optical information recording medium in which an interference pattern between a signal light and a reference light with redundant information recorded as a hologram is reproduced by a phase conjugate method,
A light source that emits a light beam;
An optical element for separating the light beam into signal light and reference light;
A spatial light modulator for adding two-dimensional information to the signal light;
A photodetector for receiving diffracted light obtained by irradiating the reference light to the optical information recording medium;
A reflected light shielding unit for preventing a part of the diffracted light from being reflected by the spatial light modulator and entering the light detection unit;
The reflected light shielding unit is an optical information recording / reproducing apparatus having a light shielding member in front of an incident surface of the spatial light modulator.   The optical information recording / reproducing apparatus according to claim 1, wherein the light shielding member is configured using a light absorbing material. The reflected light shielding unit has a mechanism for moving the light shielding member;
When information is recorded on the optical information recording medium, the light shielding member is moved so that signal light is incident on the spatial light modulator, and information recorded on the optical information recording medium is reproduced. 2. The optical information recording / reproducing apparatus according to claim 1, wherein the light shielding member is moved so that the diffracted light is not incident on the spatial light modulator.   The light shielding member has a shutter shape, and when recording information on the optical information recording medium, the light shielding member is opened so that signal light is incident on the spatial light modulator, and recording is performed on the optical information recording medium. 2. The optical information recording / reproducing apparatus according to claim 1, wherein when reproducing the recorded information, the light shielding member shields the diffracted light from entering the spatial light modulator. In an optical information recording / reproducing apparatus for reproducing by an optical information recording medium in which an interference pattern between a signal light with redundant information and a reference light is recorded as a hologram by a phase conjugate method,
A light source that emits a light beam;
An optical element for separating the light beam into signal light and reference light;
A spatial light modulator for adding two-dimensional information to the signal light;
A photodetector for receiving diffracted light obtained by irradiating the reference light to the optical information recording medium;
An optical information recording / reproducing apparatus comprising: a spatial light modulator moving unit that moves the spatial light modulator.   6. The optical information recording / reproducing apparatus according to claim 5, wherein the spatial light modulator moving unit moves to a position where the diffracted light is not incident on the spatial light modulator during reproduction. A light source that emits a light beam, an optical element that separates the light beam into signal light and reference light, a spatial light modulator for adding two-dimensional information to the signal light, and the reference light on an optical information recording medium Information is made redundant by using an optical information recording / reproducing apparatus including a photodetector that receives diffracted light obtained by irradiating light and a reflected light shielding unit having a light shielding member in front of the spatial light modulator. An optical information recording / reproducing method for reproducing by an optical information recording medium recorded as a hologram with an interference pattern of signal light and reference light by a phase conjugate method,
Separating the light beam into signal light and reference light by the optical element;
Adding two-dimensional information to the signal light using the spatial light modulator;
Receiving the diffracted light obtained by irradiating the reference light onto the optical information recording medium with the photodetector;
An optical information recording / reproducing method including a reflected light shielding step for preventing a part of the diffracted light from being reflected by the spatial light modulator and entering the light detection unit during reproduction.   In the reflected light shielding step, when reproducing information recorded on the optical information recording medium, the light shielding member is moved to a position where the diffracted light is not incident on the spatial light modulator by a mechanism that moves the light shielding member. The optical information recording / reproducing method according to claim 7, wherein the optical information recording / reproducing method is moved.   In the reflected light shielding step, when reproducing information recorded on the optical information recording medium, the light shielding member shields the diffracted light from being incident on the spatial light modulator by the shutter-shaped light shielding member. The optical information recording / reproducing method according to claim 7. A light source that emits a light beam, an optical element that separates the light beam into signal light and reference light, a spatial light modulator for adding two-dimensional information to the signal light, and the reference light on an optical information recording medium Signal light with redundant information using an optical information recording / reproducing apparatus comprising: a photodetector that receives diffracted light obtained by irradiating light; and a spatial light modulator moving unit that moves the spatial light modulator. An optical information recording / reproducing method for reproducing an optical information recording medium recorded with an interference pattern between a reference beam and a reference light as a hologram by a phase conjugate method,
Separating the light beam into signal light and reference light by the optical element;
Adding two-dimensional information to the signal light using the spatial light modulator;
Receiving the diffracted light obtained by irradiating the reference light onto the optical information recording medium with the photodetector;
An optical information recording / reproducing method including a reflected light shielding step of moving to a position where a part of the diffracted light is not incident on the spatial light modulator during reproduction.

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