WO2014155550A1 - 光情報再生装置および光情報記録再生装置 - Google Patents
光情報再生装置および光情報記録再生装置 Download PDFInfo
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- WO2014155550A1 WO2014155550A1 PCT/JP2013/058905 JP2013058905W WO2014155550A1 WO 2014155550 A1 WO2014155550 A1 WO 2014155550A1 JP 2013058905 W JP2013058905 W JP 2013058905W WO 2014155550 A1 WO2014155550 A1 WO 2014155550A1
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- light
- optical information
- information recording
- hologram
- reproducing apparatus
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
- G11B7/0065—Recording, reproducing or erasing by using optical interference patterns, e.g. holograms
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/14—Measuring arrangements characterised by the use of optical techniques for measuring distance or clearance between spaced objects or spaced apertures
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
- G11B7/083—Disposition or mounting of heads or light sources relatively to record carriers relative to record carriers storing information in the form of optical interference patterns, e.g. holograms
Definitions
- the present invention relates to an optical information reproducing apparatus, an optical information recording / reproducing apparatus, an optical information reproducing method, and an optical information recording / reproducing method for recording information on an optical information recording medium using holography and reproducing information from the optical information recording medium.
- 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.
- HDD Hard Disk Drive
- 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.
- 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.
- Regenerated signal light is detected two-dimensionally at high speed using a photodetector such as a CMOS or CCD.
- a photodetector such as a CMOS or CCD.
- 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.
- Patent Document 1 JP-A-2004-272268. This publication describes a technique for multiplexing and recording holograms.
- the above-described problem can be achieved, for example, by detecting a diffracted light by making a detection light for detecting a positional deviation incident on a recording medium from an optical path of a signal light during recording.
- a recorded target hologram can be accessed at a high speed, and an easy-to-use optical information recording / reproducing apparatus can be provided.
- FIG. 2 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 device 10 is connected to an external control device 91 via an input / output control circuit 90.
- 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.
- 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, a position detection optical system 15, and a rotation motor 50.
- the recording medium 1 can be rotated by a rotary motor 50.
- 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.
- 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.
- the reproduction reference light optical system 12 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 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.
- 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.
- 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 the position is controlled via the access control circuit 81.
- the recording technology using the principle of angle multiplexing of holography tends to have a very small tolerance for the deviation of the reference beam angle.
- 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.
- the pickup 11, the cure optical system 13, the disk rotation angle detection optical system 14, and the position detection optical system 15 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.
- 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.
- the optical element 304 composed of, for example, a half-wave plate.
- the light is incident on a PBS (Polarization Beam Splitter) prism 305.
- PBS Polarization Beam Splitter
- 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.
- 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.
- 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.
- 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.
- 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 a reproduction principle in an example of a basic optical system configuration of the pickup 11 in the optical information recording / reproducing apparatus 10.
- 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.
- 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.
- FIG. 5 is a diagram showing another configuration of the pickup 11.
- the light beam emitted from the light source 501 passes through the collimator lens 502 and enters the shutter 503.
- the optical element 504 configured by, for example, a half-wave plate or the like adjusts the light quantity ratio of p-polarized light and s-polarized light to a desired ratio.
- the polarization direction is controlled, the light enters the polarization beam splitter 505.
- the light beam that has passed through the polarization beam splitter 505 enters the spatial light modulator 508 via the polarization beam splitter 507.
- the signal light 506 to which information is added by the spatial light modulator 508 is reflected by the polarization beam splitter 507 and propagates through an angle filter 509 that allows only a light beam having a predetermined incident angle to pass therethrough. Thereafter, the signal light beam is focused on the hologram recording medium 1 by the objective lens 510.
- the light beam reflected from the polarization beam splitter 505 functions as reference light 512, and is set to a predetermined polarization direction according to recording or reproduction by the polarization direction conversion element 519, and then passes through the mirror 513 and the mirror 514.
- the light enters the lens 515.
- the lens 515 plays a role of condensing the reference light 512 on the back focus surface of the objective lens 510, and the reference light once condensed on the back focus surface of the objective lens 510 becomes parallel light again by the objective lens 510. Is incident on the hologram recording medium 1.
- the objective lens 510 or the optical block 521 can be driven, for example, in the direction indicated by reference numeral 520.
- the objective lens 510 and the objective lens can be driven. Since the relative positional relationship of the condensing points on the back focus surface 510 changes, the incident angle of the reference light incident on the hologram recording medium 1 can be set to a desired angle.
- the incident angle of the reference light may be set to a desired angle by driving the mirror 514 with an actuator.
- the reference light When reproducing the recorded information, the reference light is incident on the hologram recording medium 1 as described above, and the light beam transmitted through the hologram recording medium 1 is reflected by the galvanometer mirror 516 so that the reproduction reference light is reflected. Generate. The reproduction light reproduced by the reproduction reference light propagates through the objective lens 510 and the angle filter 509. Thereafter, the reproduction light passes through the polarization beam splitter 507 and enters the photodetector 518, and the recorded signal can be reproduced.
- the optical system shown in FIG. 5 has an advantage that the size can be greatly reduced by making the signal light and the reference light incident on the same objective lens as compared with the optical system configuration shown in FIG.
- FIG. 6 shows an operation flow of recording and reproduction in the optical information recording / reproducing apparatus 10.
- a flow relating to recording / reproduction using holography in particular will be described.
- FIG. 6A 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. FIG. 6C shows an operation flow until information is recorded on the information recording medium 1
- FIG. 6C shows an operation flow until the information recorded on the optical information recording medium 1 is reproduced from the ready state.
- 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. (602).
- 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.
- the operation flow from the ready state to recording information is as follows. First, data to be recorded is received (611), and information corresponding to the data is received from the spatial light modulator in the pickup 11. To send.
- 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.
- 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.
- 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).
- 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 from the ready state to the reproduction of recorded information is as follows.
- the access control circuit 81 is controlled, and the pickup 11 and the reproduction reference light are reproduced.
- the position of the optical system 12 is positioned at a predetermined position on the optical information recording medium.
- 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.
- FIG. 9 shows a data processing flow at the time of recording and reproduction.
- FIG. 9A shows the input / output control circuit 90 after receiving the recording data 611 and converting it into two-dimensional data on the spatial light modulator 312.
- FIG. 9B shows a recording data processing flow in the signal generation circuit 86 until the signal is processed.
- FIG. 9B shows the signal processing up to reproduction data transmission 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 the circuit 85 is shown.
- each data string is converted to CRC (902) so that error detection at the time of reproduction can be performed.
- the data string is scrambled (903) to add a pseudo random number data sequence, and then error correction coding (904) such as Reed-Solomon code is performed so that error correction can be performed during reproduction.
- error correction coding such as Reed-Solomon code is performed so that error correction can be performed during reproduction.
- 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).
- 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.
- error correction processing (917) is performed to remove the parity data strings.
- 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. 7 is a block diagram of the signal generation circuit 86 of the optical information recording / reproducing apparatus 10.
- the input / output control circuit 90 When the input of user data to the output control circuit 90 is started, 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.
- the CRC calculation circuit 704 performs control to convert the user data into CRC.
- the scramble circuit 705 scrambles the CRC-converted data to add a pseudo-random data sequence
- the error correction encoding circuit 706 performs error correction encoding to add the parity data sequence.
- 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. 8 is a block diagram of the signal processing circuit 85 of the optical information recording / reproducing apparatus 10.
- 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.
- the sub-controller 801 controls each signal processing circuit via the control line 811 so that the signal processing circuits are operated in parallel.
- 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.
- 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.
- 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.
- the error correction circuit 806 corrects the error included in each data string
- the scramble release circuit 805 releases the scramble to add the pseudo random number data string
- the CRC calculation circuit 804 causes an error in the user data on the memory 802. Check not included. Thereafter, user data is transferred from the memory 802 to the input / output control circuit 90.
- FIGS. 35 to 38 show the essential parts of the optical system shown in FIG.
- interference fringes of signal light and reference light are recorded.
- signal light 3501 from each pixel of the spatial light modulator 312 is recorded.
- 3502 intersect in the optical information recording medium 1 to form interference fringes and recorded as a hologram 3503. Therefore, as shown in FIG. 36, the recorded signal light 3502 can be obtained as diffracted light 3603 by irradiating the recorded hologram 3503 with detection light 3601 which is a part of the recorded signal light.
- transmitted light 3602 is also generated.
- the signal light 3701 from the spatial light modulator 312 is condensed in the optical information recording medium 1 to form interference fringes and recorded as a hologram 3702. Therefore, as shown in FIG. 38, the recorded signal light 3701 can be obtained as diffracted light 3803 by irradiating the recorded hologram 3702 with detection light 3801 which is a part of the recorded signal light. Since this diffracted light is generated from the recorded hologram, it is possible to position the optical information recording medium 1 and / or the pickup 11 with high accuracy based on the diffracted light.
- transmitted light 3802 is also generated at the same time, the transmitted light 3802 has a larger amount of light than the diffracted light 3803. Therefore, if the light is blocked, a signal of only diffracted light can be generated, and the position detection accuracy can be improved.
- the recorded hologram is angle-multiplexed, the obtained diffracted light is a superposition of the diffracted light from all pages, and the amount of diffracted light is large.
- FIG. 1 is an example in which a position detection optical system 15 is added to the recording / reproducing apparatus of FIG. 2 to enable position control to a target hologram (book) during reproduction.
- the light beam emitted from the light source 301 and transmitted through the PBS prism 305 is enlarged by the beam expander 308 and then transmitted through the phase mask 309, the relay lens 310, and the PBS prism 311, and the spatial light modulator 312. Is incident on. Since the phase mask 309 causes a phase shift between recording and detection and diffracted light may not be obtained well, the phase mask 309 does not need to be transmitted during position detection.
- the spatial light modulator 312 is displayed on the spatial light modulator 312 at the time of recording, but images such as FIG. 11 and FIG. 12 are displayed on the spatial light modulator 312 when the position is detected.
- 11 and 12 white indicates that light is transmitted and black indicates that light is not transmitted.
- this transmission region region shown in white
- the shape of the transmissive region is not limited to a circle but may be a rectangle or the like.
- Detection light for position detection generated 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 detection light is condensed on the optical information recording medium 1 by the objective lens 315.
- the diffracted light diffracted by the detection light propagates through the relay lenses 103 and 104 and the mask 101 and enters the photodetector 102.
- the diffracted light includes detection light (0th-order diffracted light) transmitted through the optical information recording medium 1, and is thus blocked by the mask 101.
- the mask 101 uses the pattern of FIG. 14 in the case of detection light using FIG. 11, and the pattern of FIG.
- This non-transmission region can be created by disposing a material that does not transmit light, such as metal or paint, on a transparent plate. If the distance between the optical information recording medium 1 and the relay lens 103 and the distance between the relay lens 103 and the mask 101 are set to be the focal length of the relay lens 103, the image of the spatial light modulator 312 appears on the mask 101. Therefore, although it is easy to mask, it is not limited to this. Further, it is desirable that the pattern of the mask 101 be slightly larger so as to include the pattern displayed on the spatial light modulator 312 in consideration of the positional deviation and aberration of the optical information recording medium 1 and the mask. It is also possible to make the mask pattern variable by combining a liquid crystal element and a polarizing plate and changing the pattern displayed on the liquid crystal element.
- 16 and 17 are graphs showing the diffraction efficiency with respect to the movement amount of the optical information recording medium.
- the pattern of the spatial light modulator 312 can be determined in consideration of the required detection range and sensitivity.
- the detection light is generated by entering a part of the laser light from the laser light source that also generates the reference light as the detection light for detecting the positional deviation from the optical path of the signal light at the time of recording.
- a laser light source that generates detection light may be a light source different from a laser light source for generating reference light. That is, light may be incident on the optical information recording medium from the incident direction (or a part of the incident direction) of the signal light at the time of recording. In this embodiment, light that achieves such a function is generated.
- the configuration is referred to as a detection light generation unit.
- a configuration for guiding the detection light to the optical information recording medium is referred to as a detection light incident portion.
- FIG. 18 shows details of the optical information recording medium 1 and the position detection optical system 15.
- the angle of the optical information recording medium 1 is changed from that in FIG. 1, but even if it is tilted, it can be similarly applied if the tilt is taken into consideration.
- the diffracted light 1803 from the recorded hologram 1801 enters the photodetector 102 (FIG. 18A).
- a top view of the photodetector 102 is shown in FIG. 18B, and the photodetector 102 is divided into four, and generates a position detection signal according to the positions of the light spots 1804 and 1805 of the diffracted light.
- the optical information recording medium 1 and / or the pickup 11 may be controlled so that the position detection signal Ex becomes zero.
- FIG. 20 shows changes in the position detection signal Ey with respect to the Y direction.
- the optical information recording medium 1 and / or the pickup 11 may be controlled so that the position detection signal Ey becomes zero.
- the position detection signals Ex and Ey are small, it is also effective to normalize with the luminance of (A + B + C + D).
- the position detection signal may be (A + B + C + D), and control may be performed so that the position detection signal becomes maximum.
- the control target of the pickup 11 may be all components of the pickup 11 or a part of the constituent elements such as the spatial filter 314 and the objective lens 315. Further, the definitions of X, Y, ⁇ , and r described here are not limited, and can be applied in the same manner regardless of the shape of the disk, such as a disk or a square.
- FIG. 21 shows a processing flow during reproduction.
- the pattern of FIG. 12 is displayed on the spatial light modulator 312 (2101), and the polarization direction is controlled by the optical element 304 so as to generate detection light (2102).
- the optical information recording medium 1 is irradiated with the detection light, the rotation angle is controlled so that the position detection signal Ex becomes 0 (2104), and then the position detection signal Ey becomes 0.
- the radial position is controlled so as to become (2105).
- the polarization direction is controlled by the optical element 304 so as to generate reference light for reading data (2106).
- the generated reference light is applied to the optical information recording medium 1 to read out the book information (2107). These operations from 2102 to 2107 are repeated until the reproduction is completed (2108).
- the book position is adjusted every time, but steps 2102, 2104, and 2105 can be speeded up by being performed every several books.
- the pattern displayed on the spatial light modulator 312 has been described with reference to FIG. 12, but the present invention is not limited to this. Any detection light may be used as long as it includes a part of signal light during recording. . Further, the order of step 2104 and step 2105 may be reversed.
- the first embodiment described above it is possible to use a signal of a photodetector that generally has a fast response speed, and to control a position where the detection signal is 0 as a target, thereby enabling high-speed and high-accuracy position control. It becomes possible.
- the spatial light modulator 312 is used to generate detection light including a part of the recorded signal light.
- the present invention is not limited to this, and a separate detection optical system is provided. May be. For example, by reducing the light beam diameter by the beam expander 308, the light blocked by the spatial light modulator 312 is reduced, and the efficiency can be improved. The same applies to the following embodiments.
- This embodiment differs from the first embodiment in the position control procedure and the display pattern of the spatial light modulator 312. As described above, it is possible to arbitrarily set the position detection range and sensitivity by changing the pattern of the spatial light modulator 312. However, if the position detection range is increased, the sensitivity near the adjustment target is lowered. End up.
- the first position detection image with a small radius of the transmission region in FIG. 12 so as to increase the position detection range and the transmission region in FIG. 12 so that the sensitivity in the vicinity of the target becomes high.
- the second position detection image having a radius larger than that of the first position detection image, both the position detection range and the sensitivity are achieved.
- the position control procedure of the present embodiment will be described using the processing flow of FIG.
- the first position detection image having a small radius in FIG. 12 is displayed on the spatial light modulator 312 (2201), and the polarization direction is controlled by the optical element 304 so as to generate detection light (2102). ).
- the optical information recording medium 1 is irradiated with the detection light, the rotation angle is controlled so that the position detection signal Ex becomes 0 (2104), and then the position detection signal Ey becomes 0
- the radial position is controlled so as to become (2105).
- step 2104 and step 2105 may be reversed.
- high-speed and high-accuracy position control that achieves both a position detection range and sensitivity can be achieved by changing the size of the detection light.
- This embodiment differs from the first embodiment in the position control procedure. Generally, it takes time to change the polarization direction of the optical element 304 as in the processing flow of FIG. 21 of the first embodiment. Therefore, this problem does not occur if the polarization direction of the optical element 304 is controlled so as to always generate both detection light and reference light as shown in FIG. FIG. 23 is different from FIG. 4, which is a configuration diagram at the time of reproduction, in that the position detection optical system 15 and the shutter 2301 are arranged and light is transmitted also to the signal light side at the time of reproduction.
- the position control procedure of the present embodiment will be described using the processing flow of FIG.
- the pattern of FIG. 12 is displayed on the spatial light modulator 312 (2101), and the polarization direction is controlled by the optical element 304 so as to generate detection light and reference light (2401).
- the subsequent steps are the same as in the first embodiment, and the operations from 2103 to 2107 are repeated until the reproduction is completed (2108).
- step 2104 and step 2105 may be reversed.
- This embodiment differs from the first embodiment in the position detection optical system 15 and the hologram position detection method.
- the first embodiment when it is difficult to control in the vicinity of the target book position as in step 2103 of FIG. 21, there is a risk that the adjacent book will be erroneous. Therefore, this problem does not occur if a page on which a target book can be searched is recorded.
- FIG. 25 shows the book search page of this embodiment.
- An address pattern 2501 unique to the book or different from the adjacent book is arranged at the center, and an annular reference pattern 2502 is arranged around the address pattern 2501.
- this address pattern 2501 can be easily associated with the book address, it is desirable that the address pattern 2501 has a low correlation with an adjacent book or a nearby book in order to avoid erroneous detection.
- the reference pattern is not limited to the reference pattern 2502, and it is preferable that the reference pattern be smaller than the signal light region in order to widen the detection range.
- detection light is generated by displaying the address pattern 2501 of the target book on the spatial light modulator 312. Thereby, strong diffracted light can be obtained only when the hologram of the target book is irradiated with detection light.
- the mask 101 blocks an area including the address pattern 2501 as shown in FIG.
- FIG. 28 shows changes in the position detection signal Eall with respect to the X direction. Since Eall is maximized at the center of the target book position, the optical information recording medium 1 and / or the pickup 11 may be controlled so that the position detection signal Eall is maximized.
- FIG. 29 shows a processing flow.
- the polarization direction is controlled by the optical element 304 so as to generate signal light and reference light (2901).
- it is positioned at the target book position (2902), a book search page having the address pattern of the target book is displayed on the spatial light modulator 312, and the optical information recording medium 1 is irradiated and recorded (2903).
- a normal page is angle-multiplexed and recorded while changing the reference beam angle (2904).
- These operations from 2902 to 2904 are repeated until recording is completed (2905).
- book search pages are recorded every book, but step 2903 can be speeded up by being performed every several books.
- FIG. 30 shows a processing flow.
- the polarization direction is controlled by the optical element 304 so as to generate detection light (3001), and the address pattern of the target book is displayed on the spatial light modulator 312 (3002).
- the optical information recording medium 1 is irradiated with detection light, and the position detection signal Eall is detected while moving the optical information recording medium 1 (3004).
- the position detection signal Eall increases at the target book position.
- the position detection signal Eall is not 0 because part of the address pattern matches at other book positions, but should be smaller than the position detection signal Eall at the target book position. Therefore, a threshold value is determined in advance, and if it is larger than the threshold value, the target book position is determined, and the movement of the optical information recording medium 1 is stopped (3005). Thereafter, the book is reproduced by the method of the first embodiment (3006). These operations from 3002 to 3006 are repeated until reproduction is completed (3007). In the above example, the book search is performed every time. However, steps 3002 to 3005 can be speeded up by performing only the first reading book or every several books. In addition, although steps 3004 and 3005 have been described as moving the optical information recording medium 1, the pickup 11 may be moved.
- a target book can be searched at high speed, and high-speed and high-accuracy position control can be performed without erroneously controlling adjacent books.
- the book search page as shown in FIG. 25 is recorded.
- the address pattern 2501 is incorporated in a normal page as shown in FIG. 32, there is no need to record the book search page. .
- the position and size of the address pattern are not limited to the address pattern 2501, and may be arranged anywhere on the page. However, a smaller size is preferable for a book search because a wider detection range can be obtained.
- the phase mask 309 causes a phase shift between recording and detection, and diffracted light may not be obtained well. Therefore, when recording and / or reproducing a book search page, the phase mask 309 may not be transmitted.
- the position detection optical system 15 is different from the first embodiment.
- the first embodiment relates to position control in the X and Y directions, but this embodiment enables position control in the Z direction (focus direction).
- FIG. 33 shows details of the optical information recording medium 1 and the position detection optical system 15. What differs from FIG. 18 is a cylindrical lens 3301.
- a cylindrical lens is a lens waiting for a cylindrical refractive surface.
- the cylindrical lens 3301 is disposed with an inclination of 45 ° from the X axis so that the inclination of the cylinder axis coincides with the inclination of the diagonal line of the photodetector 102.
- the direction to be divided can be shared with the position detection in the X and Y directions, which is efficient.
- the angle of the optical information recording medium 1 is changed from that in FIG. 1, but even if it is inclined, it can be similarly applied by considering the inclination.
- the top view of the photodetector 102 is shown in FIG. 33B, and the focal lengths and positions of the cylindrical lens 3301 and the relay lens 104 are determined so that the light spot 1804 of the diffracted light is a perfect circle.
- FIG. 34 shows changes in the position detection signal Ez with respect to the Z direction.
- the optical information recording medium 1 and / or the pickup 11 may be controlled so that the position detection signal Ez becomes zero.
- this invention is not limited to the above-mentioned Example, Various modifications are included.
- 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.
- 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.
- 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 that realize 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.
- 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.
- SYMBOLS 1 Optical information recording medium, 10 ... Optical information recording / reproducing apparatus, 11 ... Pickup, 12 ... Reference optical system for reproduction
- relay lens 104 ... relay lens 301 ... light source 302 ... -Collimating lens 303 ... Shutter, 304 ... 1/2 wavelength plate, 305 ... Polarizing beam splitter, 306 ... Signal light, 307 ... Reference light, 308 ... Beam expander, 309 ... Phase (Phase) mask, 310 ... relay lens, 311 ... polarization beam splitter, 312 ... spatial light modulator, 313 ... relay lens, 314 ... spatial filter, 315 ... objective lens, 316: Polarization direction conversion element, 317 ... Mirror, 318 ... Mirror, 319 ... Mirror, 320 ... Actuator, 321 ... Lens, 322 ... Lens, 323 ...
- Actuator 324 mirror, 325 ... photodetector, 501 ... light source, 502 ... collimating lens, 503 ... shutter, 504 ... optics 505... Polarization beam splitter, 506... Signal light, 507... Polarization beam splitter, 508... Spatial light modulator, 509. ... Phase mask, 512 ... Relay lens, 513 ... Spatial filter, 514 ... Mirror, 515 ... Mirror, 516 ... Mirror, 517 ... Actuator, 518 ... ⁇ Photodetector 519... Lens 520... Lens 521... Mirror 522... Actuator 523 .. reference light 524. Lens, 1801... Hologram, 1802... Hologram, 1803...
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Abstract
Description
図22の処理フローを用いて本実施例の位置制御手順について説明する。目標ブックを再生する場合、図12の半径が小さい第1位置検出用画像を空間光変調器312に表示し(2201)、検出光を生成するように光学素子304により偏光方向を制御する(2102)。次に目標ブック位置近傍に位置付け(2103)、検出光を光情報記録媒体1に照射し、位置検出信号Exが0となるよう回転角度を制御(2104)、続いて位置検出信号Eyが0となるよう半径位置を制御する(2105)。次に図12の半径が大きい第2位置検出用画像を空間光変調器312に表示し(2202)、位置検出信号Exが0となるよう回転角度を制御(2203)、続いて位置検出信号Eyが0となるよう半径位置を制御する(2304)。以降は第1の実施例と同様であり、これら2201から2107までの動作を再生が完了するまで繰り返す(2108)。なお、以上の例では毎ブック位置調整をしているが、ステップ2201、2104、2105は数ブック毎に実施してもよい。また、空間光変調器312に表示するパターンを図12で説明したがこれに限定するものではなく、第1位置検出用画像と第2位置検出用画像の形状を変えていれば何を使用してもよい。また、ステップ2104とステップ2105、ステップ2203とステップ2204の順序は逆であってもよい。
Claims (15)
- 参照光と信号光とを干渉させ、得られた干渉縞をホログラムとして光情報記録媒体に記録し、前記光情報記録媒体に記録されたホログラムから参照光を用いて情報を再生する光情報記録再生装置において、
前記信号光の一部を含む光を検出光として生成する検出光生成部と、
前記検出光を記録されたホログラムに入射する検出光入射部と、
前記ホログラムに入射した前記検出光による回折光を検出する光検出部と、を有し、
前記光検出部出力に基づいて前記記録されたホログラムの位置を検出する、
ことを特徴とする光情報記録再生装置。 - 請求項1に記載の光情報記録再生装置において、
前記回折光のうち、前記ホログラムを透過した前記検出光を遮断するマスク部を有する、
ことを特徴とする光情報記録再生装置。 - 請求項1に記載の光情報記録再生装置において、
前記光検出部は複数領域に分割され、各々の領域で検出される光量に基づいて前記記録されたホログラムの位置を検出する、
ことを特徴とする光情報記録再生装置。 - 請求項1に記載の光情報記録再生装置において、
第1の検出光で前記ホログラムの位置を検出した後に、第1の検出光と異なる光束径を有する第2の検出光で前記ホログラムの位置を検出する、
ことを特徴とする光情報記録再生装置。 - 請求項1に記載の光情報記録再生装置において、
前記ホログラムの記録時にホログラム毎の固有パターンを記録し、
位置検出時には、検出するホログラムの前記固有パターンを前記検出光とする、
ことを特徴とする光情報記録再生装置。 - 請求項1に記載の光情報記録再生装置において、
前記検出光生成部は、
レーザ光を生成するレーザ光源と、
前記レーザ光源が生成するレーザ光の偏光を変える光学素子と、
前記光学素子を通過したレーザ光を信号光と参照光とにスプリッタと、
を有し、
前記スプリッタが分割した参照光により光情報記録媒体のデータを再生する場合は、該スプリッタが分割した信号光の一部を含む光を検出光として生成し続ける、
ことを特徴とする光情報記録再生装置。 - 請求項1に記載の光情報記録再生装置において、
前記ホログラムを透過した前記検出光を遮断するマスク部と、
シリンドリカルレンズと、
を有することを特徴とする光情報記録再生装置。 - 参照光と信号光とを干渉させ、得られた干渉縞をホログラムとして記録された光情報記録媒体から参照光を用いて情報を再生する光情報再生装置において、
前記信号光の一部を含む光を検出光として生成する検出光生成部と、
前記検出光を記録されたホログラムに入射する検出光入射部と、
前記ホログラムに入射した前記検出光による回折光を検出する光検出部と、を有し、
前記光検出部出力に基づいて前記記録されたホログラムの位置を検出する、
ことを特徴とする光情報再生装置。 - 請求項8に記載の光情報再生装置において、
前記回折光のうち、前記ホログラムを透過した前記検出光を遮断するマスク部を有する、
ことを特徴とする光情報再生装置。 - 請求項8に記載の光情報再生装置において、
前記光検出部は複数領域に分割され、各々の領域で検出される光量に基づいて前記記録されたホログラムの位置を検出する、
ことを特徴とする光情報再生装置。 - 請求項8に記載の光情報再生装置において、
第1の検出光で前記ホログラムの位置を検出した後に、第1の検出光と異なる光束径を有する第2の検出光で前記ホログラムの位置を検出する、
ことを特徴とする光情報再生装置。 - 請求項8に記載の光情報再生装置において、
前記ホログラムには、ホログラム毎の固有パターンが記録されており、
位置検出時には、検出するホログラムの前記固有パターンを前記検出光とする、
ことを特徴とする光情報再生装置。 - 請求項8に記載の光情報再生装置において、
前記検出光生成部は、
レーザ光を生成するレーザ光源と、
前記レーザ光源が生成するレーザ光の偏光を変える光学素子と、
前記光学素子を通過したレーザ光を信号光と参照光とにスプリッタと、
を有し、
前記スプリッタが分割した参照光により光情報記録媒体のデータを再生する場合は、該スプリッタが分割した信号光の一部を含む光を検出光として生成し続ける、
ことを特徴とする光情報再生装置。 - 請求項8に記載の光情報再生装置において、
前記ホログラムを透過した前記検出光を遮断するマスク部と、
シリンドリカルレンズと、
を有することを特徴とする光情報再生装置。 - 参照光と信号光とを干渉させ、得られた干渉縞をホログラムとして記録された光情報記録媒体から参照光を用いて情報を再生する光情報再生装置において、
レーザ光を生成するレーザ光源と、
前記レーザ光源が生成するレーザ光を参照光と検出光に分離するスプリッタと、
前記スプリッタにより分離された参照光を光情報記録媒体に導く参照光光学系と、
前記スプリッタにより分離された検出光を、ホログラム記録時の信号光が光情報記録媒体に入射した方向から、照射する検出光入射部と、
前記検出光入射部を通過し光情報記録媒体に入射する検出光による回折光を受光するディテクタと、
前記ディテクタの出力に応じて、前記参照光の光情報記録媒体への入射位置を調整する機構と、
を有する光情報再生装置。
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