WO2014097412A1

WO2014097412A1 - Optical information reproduction apparatus and optical information reproduction method

Info

Publication number: WO2014097412A1
Application number: PCT/JP2012/082859
Authority: WO
Inventors: 真弓長吉; 嶋田　堅一; 和良山崎; 誠保坂; 利樹石井
Original assignee: 日立コンシューマエレクトロニクス株式会社
Priority date: 2012-12-19
Filing date: 2012-12-19
Publication date: 2014-06-26

Abstract

Provided is an optical information recording and reproduction apparatus and an optical information recording and reproduction method that enable high quality signals to be reproduced at high speed. This optical information reproduction apparatus reproduces information from an optical information recording medium whereon an interference pattern of signal light and reference light is recorded as page data. The optical information reproduction apparatus is characterized by being provided with: a laser light source; a splitting element that splits light emitted from the laser light source into signal light and reference light; a filter that minimizes the effects of crosstalk between adjacent holograms; a light detection unit that detects a position error signal of the filter from diffracted light that is diffracted when the optical information recording medium is irradiated with the reference light; and a control unit that controls the filter. The optical information reproduction apparatus is further characterized in that the control unit controls the filter in response to the position error signal detected by the light detection unit.

Description

Optical information reproducing apparatus and optical information reproducing method

The present invention relates to an apparatus for recording information on an optical information recording medium using the interference pattern of signal light and reference light as page data and / or reproducing information from the optical information recording medium.

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 disk, a high-density technology by a new method different from a high-density technology by shortening the wavelength and increasing the NA of the objective lens is necessary.

While research on next-generation storage technology is underway, hologram recording technology that records digital information using holography is drawing attention.

Hologram recording technology is a method in which signal light having page data information two-dimensionally modulated by a spatial light modulator is superimposed on reference light inside the recording medium, and the interference fringe pattern generated at that time is placed in the recording medium. This is a technique for recording information on a recording medium by causing refractive index modulation.

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

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

As a hologram recording technique, for example, there is JP-A-2004-272268 (Patent Document 1). This publication discloses a multiplexing method and apparatus in which holograms are spatially multiplexed by partial spatial overlap between adjacent stacks of holograms. Each stack is for example an angle, a wavelength, a phase. The full advantage of another multiplexing technique such as sign, peritropy, or fractal multiplexing can be further taken in. An amount equal to the beam waist of the signal light writing the hologram separates the individual stacks of holograms. A hologram and a hologram adjacent to the hologram are all read out simultaneously, and the adjacent hologram read out is not transmitted to the camera surface by arranging a filter at the beam waist of the reproduced data, or These undesired reproductions can be found in optical systems with limited angular passbands. Information, it is described that may be filtered. "By the intermediate plane of the angular filter.

Also, as another patent document on which a polytopic filter is mounted, there is JP-A-2007-304263 (Patent Document 2). This publication describes that “it provides a holographic memory device capable of controlling the reproduction light emitted from the reproduction target hologram to appropriately pass through the polytopic filter”.

JP 2004-272268 A JP 2007-304263 A

In Patent Documents 1 and 2, holograms are recorded adjacently at a minimum pitch for the purpose of increasing the density. Therefore, when the reproduction light is irradiated, not only the target hologram but also the adjacent hologram is reproduced simultaneously. Therefore, a spatial filter called a polytopic filter is mounted in order to remove crosstalk from adjacent holograms and reproduce only the target hologram.

By the way, in holographic recording, a reproduced image having a high SNR can be acquired when the relative position of the optical information recording medium with respect to the optical pickup coincides during recording and reproduction. However, when the optical information recording medium is exchanged between recording and reproduction, when using a different optical information recording / reproducing apparatus, or due to various factors such as temperature change, vibration influence, change with time, etc. A relative displacement of the recording medium occurs. If the relative position of the optical information recording medium and the polytopic filter is shifted, vignetting of diffracted light occurs in the polytopic filter, resulting in a lack of a part of the reproduced image or a decrease in the amount of light. As a result, there arises a problem that the SNR deteriorates. Defocusing and detracking can be considered as specific examples of positional deviation. In such a case, in Patent Document 2, the position of the optical information recording medium is adjusted during reproduction to correct the relative position to the optical pickup. However, since the optical information recording medium is relatively heavy, there is a problem that it takes time for reproduction.

Therefore, an object of the present invention is to provide an optical information recording / reproducing apparatus and an optical information recording / reproducing method capable of reproducing a high-quality signal at high speed.

The above problem is solved by, for example, the invention described in the scope of claims.

According to the present invention, it is possible to provide an optical information recording / reproducing apparatus and an optical information recording / reproducing method capable of reproducing a high-quality signal at high speed.

The figure which shows 1st embodiment of the optical pick-up of this invention The figure which shows 2nd embodiment of the optical pick-up of this invention The figure explaining the role of the polytopic filter mounted in the optical pick-up of this invention The figure which shows some embodiment of the optical pick-up at the time of a detrack The figure which shows embodiment of the detrack correction method The figure which shows embodiment of the detrack correction method of this invention The figure which shows the verification result by the simulation of the detrack correction method of this invention The figure which shows some embodiment of the optical pick-up to which this invention is applied The figure which shows some embodiment of the optical pick-up to which this invention is applied Example of experimental results The figure which shows the verification result by the simulation at the time of the defocusing of this invention Schematic showing a method of generating a signal corresponding to defocus according to an embodiment of the present invention Schematic showing a method for generating a signal corresponding to detrack and defocus according to an embodiment of the present invention. Schematic showing the Example of the optical information recording / reproducing apparatus of this invention Schematic showing an embodiment of the operation flow of the optical information recording / reproducing apparatus Schematic showing the Example of the operation | movement flow of the polytopic filter three-dimensional control of this invention

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an example of an optical system configuration of an optical pickup 11 in an optical information recording / reproducing apparatus 10 of the present invention.

First, the hologram recording procedure will be described. The light beam emitted from the light source 101 passes through the collimator lens 102 and enters the shutter 103. When the shutter 103 is open, after the light beam passes through the shutter 103, the optical element 104 composed of, for example, a half-wave plate or the like makes the light quantity ratio of p-polarized light and s-polarized light a desired ratio. After the polarization direction is controlled, the light enters a PBS (Polarization Beam Splitter) prism 105.

The light beam that has passed through the PBS prism 105 functions as the signal light 106, and after the light beam diameter is enlarged by the beam expander 108, the light beam passes through the phase mask 109, the relay lens 110, and the PBS prism 111 and passes through the spatial light modulator 112. Is incident on.

The signal light to which information is added by the spatial light modulator 112 reflects the PBS prism 111 and propagates through the relay lens 113 and the polytopic filter 114. Thereafter, the signal light is condensed on the optical information recording medium 1 by the objective lens 115.

On the other hand, the light beam reflected from the PBS prism 105 works as reference light 107 and is set to a predetermined polarization direction according to recording or reproduction by the polarization direction conversion element 116, and then galvanically via the mirror 117 and the mirror 118. Incident on the mirror 119. Since the angle of the galvanometer mirror 119 can be adjusted by the actuator 120, the incident angle of the reference light incident on the optical information recording medium 1 after passing through the lens 121 and the lens 122 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 written by writing this pattern on the optical information recording medium. Record. Further, since the incident angle of the reference light incident on the optical information recording medium 1 can be changed by the galvanometer mirror 119, recording by angle multiplexing is possible.

Next, the hologram playback procedure will be described. The reference light 107 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 galvano mirror 124 whose angle can be adjusted by the actuator 123, thereby generating the reproduction reference light. .

The reproduction light reproduced by the reproduction reference light propagates through the objective lens 115, the relay lens 113, and the polytopic filter 114. Thereafter, the reproduction light passes through the PBS prism 111 and enters the photodetector 125, and the recorded signal can be reproduced. As the photodetector 125, an image sensor such as a CMOS image sensor or a CCD image sensor can be used, but any element may be used as long as page data can be reproduced.

FIG. 2 is a diagram showing another configuration of the optical pickup 11. In FIG. 2, the light beam emitted from the light source 201 passes through the collimator lens 202 and enters the shutter 203. When the shutter 203 is open, after the light beam passes through the shutter 203, the optical element 204 composed of, 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. After the polarization direction is controlled, the light enters the polarization beam splitter 205.

The light beam that has passed through the polarization beam splitter 205 enters the spatial light modulator 208 via the polarization beam splitter 207. The signal light 206 to which information is added by the spatial light modulator 208 is reflected by the polarization beam splitter 207 and propagates through an angle filter 209 having a characteristic of allowing only a light beam having a predetermined incident angle to pass therethrough. Thereafter, the signal light beam is condensed on the optical information recording medium 1 by the objective lens 210.

On the other hand, the light beam reflected by the polarization beam splitter 205 works as reference light 212 and is set to a predetermined polarization direction according to recording or reproduction by the polarization direction conversion element 219, and then passes through the mirror 213 and the mirror 214. The light enters the lens 215. The lens 215 plays a role of condensing the reference light 212 on the back focus surface of the objective lens 210, and the reference light once condensed on the back focus surface of the objective lens 210 becomes parallel light again by the objective lens 210. To the optical information recording medium 1.

Here, the objective lens 210 or the optical block 221 can be driven, for example, in the direction indicated by reference numeral 220. By shifting the position of the objective lens 210 or the optical block 221 along the driving direction 220, the objective lens 210 and the objective lens are moved. Since the relative positional relationship of the condensing points on the back focus surface 210 changes, the incident angle of the reference light incident on the optical information recording medium 1 can be set to a desired angle. Instead of driving the objective lens 210 or the optical block 221, the incident angle of the reference light may be set to a desired angle by driving the mirror 214 with an actuator.

In this way, by causing the signal light and the reference light to enter the optical information recording medium 1 so as to overlap each other, an interference fringe pattern is formed in the optical information recording medium, and information is written by writing this pattern on the recording medium. Record. Further, by shifting the position of the objective lens 210 or the optical block 221 along the driving direction 220, the incident angle of the reference light incident on the optical information recording medium 1 can be changed, so that recording by angle multiplexing is possible. .

When reproducing 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 216, thereby reproducing the reproduction reference. Produce light. The reproduction light reproduced by the reproduction reference light propagates through the objective lens 210 and the angle filter 209. Thereafter, the reproduction light passes through the polarization beam splitter 207 and enters the photodetector 218, and the recorded signal can be reproduced.

The optical system shown in FIG. 2 has an advantage that the signal light and the reference light are made incident on the same objective lens, so that the optical system can be greatly reduced in size as compared with the optical system configuration shown in FIG.

FIG. 3 illustrates an example of the role of the polytopic filter 114 installed in the optical system of FIG. In the holographic memory device of this embodiment, holograms are recorded at the minimum pitch for the purpose of increasing the density. Therefore, when the reproduction light is irradiated, not only the target hologram but also the adjacent hologram is reproduced simultaneously. Therefore, by placing a relatively light spatial filter called a polytopic filter at the condensing position of the relay lens 304, the reproduction light from the adjacent hologram is shielded and only the reproduction light from the target hologram is allowed to pass. be able to.

In the optical system of FIG. 2, an angle filter is used instead of the polytopic filter. Thereby, the optical pickup 11 can be reduced in size. An angle filter is a filter having an angle characteristic that transmits only light incident at a predetermined angle. The angle filter is designed so that the diffracted light of the hologram to be reproduced passes through the angle filter. At this time, the diffracted light of the adjacent hologram that enters the angle filter at an angle different from the design angle does not pass through the filter. Therefore, this filter can remove the crosstalk from the adjacent hologram as in the polytopic filter.

Hologram recording / reproduction is performed according to the procedure described with reference to FIGS. 1 and 2, but in order to obtain a high SNR reproduction image by recording high-contrast interference fringes, the wavefronts at the time of recording and reproduction are the same. It is ideal to do it. However, when the optical information recording medium is exchanged during recording and reproduction, or when a different optical information recording / reproducing apparatus is used, a relative displacement between the optical pickup 11 and the optical information recording medium 1 may occur. is there. In addition, as a cause of displacement of the optical components / structural components constituting the optical pickup 11, due to temperature changes in the optical information recording / reproducing apparatus, the adhesive or screws that fix the components expand / contract, or It is conceivable that the optical information recording medium 1 is expanded or contracted due to vibration or change with time. Due to these various factors, a relative positional shift of the optical information recording medium 1 with respect to the optical pickup 11 occurs. Detracking and defocusing can be cited as main positional deviations.

FIG. 4 shows a part of the optical system configuration when the optical information recording medium 1 is detracked during hologram reproduction, taking the optical pickup 11 of FIG. 1 as an example. When detracking occurs, the diffracted light from the hologram to be reproduced is displaced relative to the optical pickup. As a result, vignetting of diffracted light occurs in the polytopic filter 405, resulting in a problem that the SNR deteriorates due to a lack of a part of the reproduced image or a decrease in the amount of light.

The solution to this problem is shown in FIG. 5 and FIG. As shown in FIG. 5, for example, by adjusting the position of the optical information recording medium 1 according to the detrack amount, the diffracted light from the hologram to be reproduced passes through the polytopic filter 505, and a high SNR reproduced image is obtained. it can. However, since the optical information recording medium 1 is relatively heavy, there is a problem that high-speed position adjustment is difficult.

Therefore, the feature of this embodiment is that the position of the polytopic filter is adjusted according to the detrack amount and / or the defocus amount corresponding to the positional deviation of the filter. FIG. 6 shows a part of an optical pickup in which the position of the polytopic filter 605 is adjusted according to the detrack amount. Since the polytopic filter is relatively light, the position can be adjusted at a higher speed than the optical information recording medium 1. For example, the polytopic filter is considered to be composed of an actuator unit 630 and a positional deviation correction unit 611 having an arithmetic circuit. Although not shown, it is assumed that the reproduction optical path of the optical pickup is partly divided by the light dividing element, and the divided light is received by the light receiving element. Since the position of the hologram to be reproduced and the polytopic filter are relatively shifted during detracking, the position of the polytopic filter with respect to the hologram to be reproduced is detected by the light receiving element, and the signal is calculated to correspond to the position deviation. Is generated by an arithmetic circuit. Based on the signal, the actuator section 630 adjusts the position of the polytopic filter in the three-dimensional direction of detrack (radial and tangential directions) and defocus. As an example, signals from the rotary encoder detection system 607 and the linear encoder detection system 608 are calculated to generate a signal corresponding to detrack, and the position of the polytopic filter 605 is corrected accordingly. At the time of defocusing, the light emitted from the optical information recording medium is detected by an arbitrary sensor 610, and a signal corresponding to defocusing is generated to correct the position of the polytopic filter 605. Alternatively, by combining the methods described above, first, the position of the optical information recording medium 1 may be roughly adjusted, and then the position of the polytopic filter 605 may be finely adjusted to perform position correction.

Note that the position correction in the three-dimensional direction of the polytopic filter has been described with reference to the optical pickup 11 of FIG. 1 as an example in FIG. 6, but it can also be applied to the optical pickup 11 of FIG. When the optical information recording medium 1 is displaced in the optical pickup 11 shown in FIG. 2, the angle of the reproduction light incident on the angle filter 209 changes, so that the angle of the light transmitted through the angle filter is changed. An angle shift correction unit and an arithmetic circuit that applies an angle shift signal to the angle shift correction unit are mounted, and the angle characteristics of the filter are adjusted so that the diffracted light from the target hologram is not vignetted. As an example of an angle filter, like a liquid crystal filter, when no voltage is applied, light incident at all incident angles is transmitted. However, when a voltage is applied, the arrangement of liquid crystal molecules changes, and a certain predetermined incident angle is obtained. It is possible to have a property such as transmitting only the light. As an example of the angle deviation correction method of the angle filter, for example, a method of changing the angle of light that can be transmitted by changing the applied direction of the liquid crystal molecules to change the alignment direction of the liquid crystal molecules is conceivable.

In this embodiment, the polytopic filter and the angle filter are mainly described. However, similar to these filters, the reproduction light from the adjacent hologram is shielded and only the reproduction light from the target hologram is passed. Other filters may be used as long as they are filters. For example, the spatial filter may be composed of a liquid crystal element or the like, and other methods such as mechanically changing the shape of the opening are not limited to the liquid crystal element.

FIG. 7 shows the result of verifying the effect of the polytopic filter correction of this embodiment with an optical simulator. In the case of an ideal state with a detrack amount of 0, if the relative value of the SNR of the acquired reproduced image is 1.0, the SNR of the reproduced image decreases to −0.1 when a predetermined amount of detrack occurs. To do. At this time, if the position of the polytopic filter is corrected according to the detrack amount, the SNR becomes 1.0, which is improved to be equal to the ideal state.

FIG. 8 shows a part of the optical pickup during (a) recording and (b) reproduction. Assuming that the relative position between the polytopic filter and the optical information recording medium is ideal during recording, and the optical information recording medium is detracked during reproduction, the light beam in the optical element constituting the reproduction unit is used during recording and reproduction. The optical path is different. For this reason, for example, in a lens, a relatively large aberration may occur in a light beam that passes through the end of the lens, even if the light beam passes through a region that has a symmetrical optical path in the lens. FIG. 8C shows an experimental result of verifying the polytopic filter correction of this embodiment. If the relative value of the SNR of the acquired reproduced image is 1.0 when the detrack amount is 0 (nominal), the SNR of the reproduced image is reduced to about 0.85 when a predetermined amount of detrack occurs. To do. On the other hand, when the position of the polytopic filter is corrected according to the detrack amount, the SNR becomes 0.98, which is improved as compared with the detrack time, but does not completely return to the SNR in the ideal state. As one of the causes, it is presumed that the aberration of the lens occurs due to the change of the optical path of the light beam in the lens. Therefore, by designing the lens image height characteristics optimally according to the optical system, even when the optical information recording medium is detracked and the optical path during reproduction is changed, a large aberration is generated compared with the recording. Therefore, it is considered that the SNR improves to the same level as the ideal state. In addition, for example, depending on the optical system in which the optical information recording medium is tilted, there may be factors other than lens aberration, such as a focus position shift during detracking. In this case, besides the polytopic filter correction, it is possible to improve the SNR to an ideal state by detecting a deviation signal.

FIG. 9 shows the result of verifying the effect of the polytopic filter correction of this embodiment with an optical simulator. In the case of an ideal state with a defocus amount of 0, the relative value of the SNR of the acquired reproduced image is set to 1.0. If the defocus amount is increased while the position of the polytopic filter is fixed, the SNR of the reproduced image gradually deteriorates, and when the defocus amount is 100 μm, the SNR decreases to −0.2. On the other hand, when the position of the polytopic filter is corrected according to the defocus amount, the SNR is improved to 1.0, which is equivalent to the ideal state.

From the above, in FIG. 7 to FIG. 9, it was confirmed that the SNR was increased by the polytopic filter correction of this example.

FIG. 10 is a schematic diagram showing a signal generation method corresponding to defocus according to the embodiment of the present invention. (A) to (c) respectively show cases where the hologram is displaced in the focus direction, (a) is a state in which the hologram is close to the objective lens by a certain distance from the just focus position, and (b) is A state where the hologram is at the just focus position, (c) is a light ray diagram in a state where the hologram is at a certain distance from the just focus position with respect to the objective lens. Although not shown, since a part of the reproduction light of the optical pickup 11 is divided before each figure and the divided light is passed through the cylindrical lens, the light beam passes through the direction in which the cylindrical lens has a convergence effect. Astigmatism occurs because 1001 condenses quickly, and light ray 1002 passing through a direction having no lens effect condenses slowly. Utilizing this, a diagram in which light is received by the four-divided PD 1003 is shown on the right side of (a) to (c), and the beam spot 1004 changes according to the position in the focus direction. Assuming that the light receiving surface obtained by dividing the PD 1003 into four is A, B, C, and D clockwise from the upper left, a signal corresponding to defocusing is generated by calculating the signal (A + C) − (B + D). When (A + C) − (B + D)> 0, the focus is shifted forward. If (A + C)-(B + D) = 0, it is the just focus position. Conversely, when (A + C) − (B + D) <0, it indicates that the focus is shifted to the back side.

FIG. 11 is a schematic diagram showing a method for generating a signal corresponding to defocusing and a signal corresponding to detracking according to the embodiment of the present invention. As shown in the upper left of the figure, when the vertical direction is the radial direction and the horizontal direction is the tangential direction, the signal (A + B) − (C + D) is calculated by calculating the signal (A + B) − (C + D) among the signals output from the four-segment PD 1101. A signal corresponding to the radial detrack of the information recording medium 1 can be acquired. Further, by calculating the signal (A + D) − (B + C), a signal corresponding to the detrack in the tangential direction of the optical information recording medium 1 can be acquired. The signal corresponding to the defocus of the optical information recording medium 1 is (A + C) − (B + D) as described with reference to FIG. Reference numerals 1102 to 1110 denote an addition circuit and a subtraction circuit, respectively. These three signals are applied to the actuator unit, and the polytopic filter is driven three-dimensionally. The optical pickup 11 shown in FIG. 1 detects a predetermined amount of signal according to the detrack amount and the defocus amount described above. The position adjustment in the detrack direction and the defocus direction is performed by feeding back the difference between this signal and the signal corresponding to the initial position of the optical information recording medium to the actuator of the polytopic filter. Here, the signals corresponding to the initial position of the optical information recording medium are a detrack signal and a focus signal which are detected in advance during recording, and the optical information recording / reproducing apparatus 10 holds this signal and the like. By doing in this way, it becomes possible to control the position of a filter appropriately.

Note that the present invention is not limited to this detection method, and a configuration in which the polytopic filter is adjusted so that the signal obtained by the detection method becomes 0 may be adopted. Note that the diffracted light from the adjacent hologram is also guided to the quadrant PD 1101 together with the diffracted light from the hologram to be reproduced. In this embodiment, the quadrant PD is sized to receive only the diffracted light from the hologram to be reproduced. . That is, the quadrant PD has a size that does not allow diffracted light from adjacent holograms to enter simultaneously.

FIG. 12 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. 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 an optical pickup 11, a reproducing reference light optical system 12, a cure optical system 13, a disk rotation angle detecting optical system 14, and a rotation motor 50. The optical information recording medium 1 is rotated. The motor 50 can be rotated.

The optical pickup 11 plays a role of emitting reference light and signal light to the optical information recording medium 1 and recording digital information on the recording medium using holography. At this time, the information signal to be recorded is sent by the controller 89 to the spatial light modulator in the optical 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 optical pickup 11 to enter the optical information recording medium 1 in the opposite direction to that during recording. Generate with. Reproduction light reproduced by the reproduction reference light is detected by a photodetector (to be described later) in the optical pickup 11, and a signal is reproduced by the signal processing circuit 85.

The polytopic filter of the present invention is located in the optical pickup 11. The correction signal generated by the misalignment correction circuit 21 is transmitted to the actuator 20 to drive the spatial filter. When an angle filter is used instead of the polytopic filter, an angle deviation correction circuit is provided.

The irradiation time of the reference light and the signal light irradiated on the optical information recording medium 1 can be adjusted by controlling the opening / closing time of the shutter in the optical 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 optical 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 quantity. be able to.

Further, the optical 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 technology 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 light angle is provided in the optical 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. Therefore, it is necessary to provide a servo mechanism for the optical information recording / reproducing apparatus 10.

Also, the optical 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. 13 shows 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. 4A 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, and FIG. The operation flow until information is recorded on the information recording medium 1, and FIG. 10C shows the operation flow until the information recorded on the optical information recording medium 1 is reproduced from the ready state.

When a medium is inserted (1301) as shown in FIG. 11A, the optical information recording / reproducing apparatus 10 determines whether the inserted medium is a medium for recording or reproducing digital information using holography, for example. The recording medium is determined (1302).

If the optical information recording medium is determined to be an optical information recording medium that records or reproduces digital information using holography as a result of discrimination of the optical information recording medium, the optical information recording / reproducing apparatus 10 controls the control data provided in the optical information recording medium. (1303), for example, information on the optical information recording medium and information on various setting conditions during recording and reproduction are obtained.

After reading out the control data, various adjustments according to the control data and learning processing (1304) related to the pickup 11 are performed, and the optical information recording / reproducing apparatus 10 is ready for recording or reproduction (1305).

As shown in FIG. 2B, the operation flow from the ready state to the recording of information is as follows. First, data to be recorded is received (1311), and the information corresponding to the data is spatially modulated in the optical pickup 11. Send it to the vessel.

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 (1312). ).

Thereafter, in the seek operation (1313), the access control circuit 81 is controlled to position the optical 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.

Thereafter, a predetermined region is precured using the light beam emitted from the cure optical system 13 (1314), and data is recorded using the reference light and signal light emitted from the pickup 11 (1315).

After recording the data, post cure is performed using the light beam emitted from the cure optical system 13 (1316). Data may be verified as necessary.

As shown in FIG. 6C, the operation flow from the ready state to the reproduction of recorded information is as follows. First, in the seek operation (1321), the access control circuit 81 is controlled to control the optical pickup 11 and the reproduction reference. The position of the optical optical system 12 is positioned at a predetermined position 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.

Thereafter, reference light is emitted from the optical pickup 11, information recorded on the optical information recording medium 1 is read (1322), and reproduction data is transmitted (1323).

FIG. 14 is an example of an operation flow of the polytopic filter three-dimensional control of the present embodiment. Here, the flow for controlling the polytopic filter for each book is illustrated. During recording, three signals are detected in advance (1400): a detrack signal (radial direction): R ₀ , a detrack signal (tangential direction): T ₀ , and a defocus signal: D ₀ . Thereafter, chucking is performed for reproducing an optical information recording medium in which data is recorded in advance (1401). First, signals from the rotary encoder and linear encoder are detected, and the initial position of the optical information recording medium is roughly adjusted (1402). Thereafter, the polytopic filter is controlled in a three-dimensional direction to finely adjust the relative position with the optical information recording medium. As described above, the coarse adjustment of the optical information recording medium and the fine adjustment of the polytopic filter can be performed accurately and at high speed.

Thereafter, the detrack signal R ₁ in the radial direction is _first detected (1403). If the difference from the signal R ₀ detected in advance during recording is not 0, an amount corresponding to (R ₁ −R ₀ ) Only the polytopic filter is finely adjusted in the radial direction (1404, 1405). Then it detects the de-track signal T ₁ of the tangential direction (1406), in the case the difference between T ₀ as with the radial direction is not zero polytopic filter by an amount corresponding to (T 1 _-T ₀₎ Fine adjustment in the tangential direction (1407, 1408). Then detects the defocus signal _{D 1} (1409), in the case the difference between the _{D 0} is not zero finely adjusted by polytopic filter in the focus direction by an amount corresponding to _{_{(D 1 -D 0) (1410}} , 1411). With the above procedure, the position adjustment of the polytopic filter with respect to the optical information recording medium has been completed, and the polytopic filter has been adjusted to a position where light does not vignett. Therefore, reproduction processing is performed here (1412). The operations 1403 to 1412 are repeated for the number of recorded books, and are repeated until the last book is reproduced. After the reproduction is finished, the positions of the radial direction, tangential direction, and defocus direction of the polytopic filter may be returned to the same positions as at the time of recording. Then, the control is terminated (1414). Procedures 1403 to 1411 may be processed in parallel.

Note that short stack recording may be performed in order to obtain a high SNR reproduction image (refer to Special Table 2010-503025 for the term “short stack”). When the short stack is performed, the steps 1403 to 1414 shown in FIG. 14 are repeated for each stack, not for each book, until the reproduction of the desired hologram is completed.

Furthermore, although not shown, the polytopic filter may be three-dimensionally controlled in real time. In this case, for example, while the optical information recording medium is rotating, the position of the polytopic filter is controlled to eliminate vignetting of the diffracted light. As a result, there is an advantage that high-speed reproduction is possible and resistance to disturbances such as vibration. For example, in the conventional method for controlling the optical information recording medium and adjusting the relative position between the optical information recording medium and the optical pickup, there is a problem that the weight of the optical information recording medium is weak against vibration. By controlling the polytopic filter in real time as in the present embodiment, reproduction that is resistant to disturbance can be achieved.

In this embodiment, the optical information recording medium is first moved and coarsely adjusted to adjust the initial position of the optical information recording medium. However, in order to increase the speed of the reproduction process, relatively heavy optical information recording is performed. The medium may not be moved, and the procedure 1402 may be skipped and the process may be started from 1403.

In the above-described embodiment, the angle multiplexing method is used. However, the present invention is not limited to this, and can be applied to, for example, a collinear method.

In addition, this invention is not limited to the above-mentioned 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.

In addition, 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.

Also, 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 ... Optical pick-up, 12 ... Reference optical system for reproduction | regeneration, 13 ... Cure optical system, 14 ... Disc Rotation angle detection optical system, 20 ... filter drive actuator, 21 ... position displacement correction circuit, 50 ... rotation motor, 81 ... access control circuit, 82 ... light source drive circuit, 83. ..Servo signal generation circuit, 84 ... servo control circuit, 85 ... signal processing circuit, 86 ... signal generation circuit, 87 ... shutter control circuit, 88 ... disc rotation motor control circuit, 89 ... Controller, 90 ... Input / output control circuit, 91 ... External control device, 101 ... Light source, 102 ... Collimating lens, 103 ... Shutter, 104 ... 1/2 wavelength plate , 105 ... Polarization beam splitter 106 ... Signal light 107 ... Reference light 108 ... Beam expander 109 ... Phase mask 110 ... Relay lens 111 ... Polarization beam splitter 112 ..Spatial light modulator, 113 ... relay lens, 114 ... polytopic filter, 115 ... objective lens, 116 ... polarization direction conversion element, 117 ... mirror, 118 ... mirror, 119 ... Mirror, 120 ... Actuator, 121 ... Lens, 122 ... Lens, 123 ... Actuator, 124 ... Mirror, 125 ... Photodetector, 130 ... Actuator, 201 ... light source, 202 ... collimating lens, 203 ... shutter, 204 ... half-wave plate, 205 ... polarized beam Ritter, 206 ... signal light, 207 ... polarization beam splitter, 208 ... spatial light modulator, 209 ... angle filter, 210 ... objective lens, 211 ... objective lens actuator, 212 ..Reference light, 213... Mirror, 214... Mirror, 215... Lens, 216... Mirror, 217... Actuator, 218. Element, 220 ... Driving direction, 221 ... Optical block, 230 ... Actuator, 301 ... Photo detector, 302 ... Polarizing beam splitter, 303 ... Spatial light modulator, 304 ... Relay lens 305 Polytopic filter 306 Objective lens 401 Photo detector 402 Polarizing beam splitter 403 ..Spatial light modulator, 404 ... relay lens, 405 ... polytopic filter, 406 ... objective lens, 501 ... photodetector, 502 ... polarizing beam splitter, 503 ... space Optical modulator, 504 ... Relay lens, 505 ... Polytopic filter, 506 ... Objective lens, 601 ... Optical detector, 602 ... Polarizing beam splitter, 603 ... Spatial light modulator 604 ... relay lens, 605 ... polytopic filter, 606 ... objective lens, 630 ... actuator, 901 ... photodetector, 902 ... polarization beam splitter, 903 ... space Optical modulator, 904 ... relay lens, 905 ... polytopic filter, 906 ... objective lens, 930 ... actuator, 1001 Light rays that have undergone the convergence effect, 1002... Rays that have not received the convergence effect, 1003... Four-segment PD, 1004... Beam spot, 1005. ..Subtracting circuit, 1101... 4 division PD, 1102... Adding circuit, 1103... Adding circuit, 1104... Adding circuit, 1105. ..Addition circuit, 1108 ... subtraction circuit, 1109 ... subtraction circuit, 1110 ... subtraction circuit

Claims

An optical information reproducing device for reproducing information from an optical information recording medium in which an interference pattern between signal light and reference light is recorded as page data,
A laser light source;
A branching element for branching light emitted from the laser light source into signal light and reference light;
A filter unit for suppressing the influence of crosstalk of adjacent holograms;
A light detection unit for detecting a position shift signal of the filter unit from diffracted light diffracted when the optical information recording medium is irradiated with the reference light;
A control unit for controlling the filter,
The said control part controls the said filter according to the said position shift signal which the said photon detection part detects, The optical information reproducing | regenerating apparatus characterized by the above-mentioned.
The optical information reproducing apparatus according to claim 1,
The filter unit is a polytopic filter;
The control unit is an actuator that drives the filter,
The optical information reproducing apparatus, wherein the actuator drives the polytopic filter in accordance with the position shift signal detected by the light detection unit.
The optical information reproducing apparatus according to claim 1,
The filter unit is an angle filter;
The light detection unit detects an angular shift of the reproduction light with respect to an incident angle of the light passing through the angle filter;
The optical information reproducing apparatus, wherein the control unit corrects an angle of light passing through the angle filter unit based on the detected angular deviation.
The optical information reproducing apparatus according to claim 2,
The light detection unit includes a light splitting element for splitting a part of the light in the reproduction optical path, and a light receiving element for receiving a part of the reproduction light split by the light splitting element,
The light receiving element includes a sensor pattern for detecting a displacement of the polytopic filter with respect to a hologram,
An optical information reproducing apparatus comprising: an arithmetic circuit that calculates a signal output from the light receiving element and generates a signal corresponding to a positional shift of the polytopic filter with respect to a hologram.
The optical information reproducing apparatus according to claim 4,
The light detection unit includes an optical element that introduces astigmatism into the reproduction light divided by the light dividing element,
The light receiving element is constituted by a four-divided sensor arranged so that a deformation direction of a beam spot caused by the astigmatism is a splashing direction,
The arithmetic circuit calculates a signal output from the quadrant sensor, and generates a signal corresponding to a positional deviation of the spatial filter with respect to the hologram in the optical axis direction of the reproduction light. apparatus.
The optical information reproducing apparatus according to claim 4,
The light receiving element includes a sensor pattern divided into two regions by a straight line,
The arithmetic circuit calculates signals output from the two regions of the light receiving element, and generates a signal corresponding to a positional deviation of the polytopic filter relative to the hologram in a direction perpendicular to the optical axis of the reproduction light. An optical information reproducing apparatus characterized by the above.
The optical information reproducing apparatus according to claim 3,
The light detection unit includes a light dividing element that divides a part thereof, and a light receiving element that receives reproduction light divided by the light dividing element,
The light receiving element includes a sensor pattern for detecting an angular deviation of the reproduction light with respect to an incident angle of the light passing through the angle filter unit,
An optical information reproducing apparatus comprising: an arithmetic circuit that calculates a signal output from the light receiving element and generates a signal corresponding to an angular deviation of the reproduction light with respect to an incident angle of the light that the angle filter passes.
The optical information reproducing apparatus according to claim 1,
The positional deviation signal is a difference signal between a detrack signal detected in advance by the light detection unit during recording and a detrack signal detected by the light detection unit during reproduction,
The optical information reproducing apparatus, wherein the control unit controls the filter according to the difference signal.
The optical information reproducing apparatus according to claim 1,
The positional deviation signal is a difference signal between a defocus signal detected in advance by the light detection unit during recording and a defocus signal detected by the light detection unit during reproduction,
The optical information reproducing apparatus, wherein the control unit controls the filter according to the difference signal.
The optical information reproducing apparatus according to claim 1,
After the position of the optical information recording medium is roughly adjusted, the control unit controls the filter according to the position shift signal detected by the light detection unit.
The optical information reproducing apparatus according to claim 1,
While the optical information recording medium is rotating, the control unit controls the filter.
An optical information reproducing method for reproducing information from an optical information recording medium in which an interference pattern between signal light and reference light is recorded as page data,
Irradiating with laser light;
Branching the laser light into signal light and reference light;
Suppressing the influence of crosstalk of adjacent holograms by a filter;
A detection step of detecting a displacement signal of the filter from diffracted light diffracted when the optical information recording medium is irradiated with the reference light;
A control step for controlling the filter,
In the control step, the filter is controlled in accordance with the positional deviation signal detected in the detection step.
An optical information reproducing method according to claim 12, comprising:
The filter is a polytopic filter;
The filter is driven by an actuator;
In the control step, the actuator drives the polytopic filter in accordance with the positional deviation signal.
An optical information reproducing method according to claim 12, comprising:
The filter is an angle filter;
In the detection step, an angular deviation of the reproduction light with respect to an incident angle of the light passing through the angle filter is detected,
The optical information reproducing method, wherein the control step corrects an angle of light passing through the angle filter based on the detected angular deviation.
The optical information reproducing method according to claim 12, comprising:
The positional deviation signal is a difference signal between a detrack signal detected in advance by the light detection unit during recording and a detrack signal detected by the light detection unit during reproduction,
The optical information reproduction method characterized in that the control step controls the filter according to the difference signal.
The optical information reproducing method according to claim 12, comprising:
The positional shift signal is a difference signal between a defocus signal detected in advance by the light detection unit during recording and a defocus signal detected by the light detection unit during reproduction,
In the control step, the filter is controlled in accordance with the difference signal.
The optical information reproducing method according to claim 12, comprising:
Roughly adjusting the position of the optical information recording medium,
An optical information reproducing method, wherein after the position of the optical information recording medium is roughly adjusted, the filter is controlled in the control step in accordance with the position shift signal detected in the detection step.
The optical information reproducing method according to claim 12, comprising:
Rotating the optical information recording medium,
The optical information reproducing method, wherein the control step controls the filter while the optical information recording medium is rotating.