JP2006228374A - Holographic recording device, device and method for reproducing, and holography medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a holography device capable of surely reproducing data under desired angle/wavelength conditions even if an angle or wavelength reference is changed when information data is reproduced from a medium in which the information data are recorded in a multiplex manner by changing an angle or a wavelength by a predetermined pitch. <P>SOLUTION: The holography device for recording data in a multiplex manner in each predetermined storage area by changing the angle of a reference light applied to a medium includes an optical modulation means for outputting a signal light modulated by information data written in the medium, a reference light applying means for changing the incident angle of the reference light interfered with a signal light, a recording means for dividing the information data and recording subdata in each divided block of the recording area, and an angle detection information writing means for writing angle detection information corresponding to each block. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a holographic recording apparatus, a reproducing apparatus and method for use in recording / reproducing information data, and a holographic medium.

2. Description of the Related Art A holographic recording system is used in which signal light composed of information data and reference light are irradiated on a holographic medium, an interference pattern is generated in the holographic medium, and the information data is recorded.
As a method for multiplex recording and reproduction of digital data consisting of “1” or “0” on this holographic medium, there is a method described in Patent Document 1 shown below and an apparatus corresponding to this method.
In this document, as a method for multiplex recording of information data at each of a plurality of locations of a holographic medium, a recording angle reproduction method in which recording and reproduction are performed by changing the angle of the reference light, and a recording by changing the wavelength of the reference light are performed. -The method of performing playback is described.

In the multiple recording method shown in Patent Document 1, in the case of writing angle multiplexing, information data recorded on a holographic medium is read with reference light for reading at an angle similar to the reference light at the time of recording. If irradiation can be performed, the information data (information data of the data page) written at a desired angle from among the multiplexed data can be arbitrarily read out.
JP 2004-177958 A

However, in the recording / reproducing method described above, when the holographic medium is irradiated with the reference light at the time of reading, the angle is the same as the angle of the reference light at the time of recording due to the mechanical accuracy in the optical system of the reproducing apparatus. There is a problem that information data cannot be read with high accuracy.
In particular, in consideration of recording with a holographic recording device and reading with a holographic reproducing device, the holographic medium needs to be loaded into the reproducing device for each reading, and the holographic medium with respect to a predetermined incident angle of reference light for each rotation Therefore, it becomes more difficult to set the reference light at the time of reading to the angle of the reference light at the time of recording.
For example, in the case of angle multiplexing, if the reference light having the same angle as the angle recorded on the medium can be incident, the data of the desired page can be reproduced by the holography reproducing device.

Further, the deviation of the angle of the reference beam may occur not only in the scanning direction for multiplexing information data pages, that is, in the Bragg diffraction direction but also in a direction perpendicular to the Bragg diffraction direction (non-Bragg direction). is there. If there is an angle shift in the non-Bragg direction both during recording and reproduction of information data, the reproduction of information data recorded on the medium is affected.
On the other hand, in the case of wavelength multiplexing, when recording / reproducing information data on a medium, for example, by adjusting the temperature of a wavelength variable laser such as a VCSEL (surface emitting semiconductor laser), the chip temperature is changed, By thermally expanding and contracting the chip, the wavelength of the emitted light is controlled according to the change of the resonance wavelength, and information data is multiplexed and recorded.
Although the temperature of the VCSEL can be controlled with an error within a certain range by adjusting the operating current, the control temperature depends on the ambient temperature and the mounting form, and the operating current and the temperature of the VCSEL are not necessarily the same. There is a problem that it is difficult to match the wavelength of the reference light used for reproduction with the wavelength of the reference light recorded on the medium during reproduction.

  The present invention has been made in view of such circumstances, and when reproducing information data from a medium on which information data is multiplexed and recorded by changing the angle and wavelength at a predetermined pitch, the angle and wavelength standards are set. It is an object of the present invention to provide a holographic recording device, a reproducing device and a method that can reliably reproduce under conditions of a desired angle or wavelength even if the angle changes (even if the angle and wavelength control accuracy is poor).

The holographic recording device according to the present invention changes the angle of the reference light applied to the holographic medium, multiplex-records information data for each predetermined storage area at different angles, and is modulated by the information data written to the holographic medium. A light modulation unit that outputs signal light; a reference light irradiation unit that changes an incident angle of reference light that interferes with the signal light with respect to the holographic medium; and sub-data in which the information data is divided into a plurality of pieces. A recording means for recording each of the blocks into divided blocks; and an angle detection information writing means for writing angle detection information indicating an angle corresponding to the block for each block in which the sub-data is written. To do.
The holographic recording method of the present invention is a holographic recording method in which the angle of the reference light applied to the holographic medium is changed, and information data is multiplexed and recorded for each predetermined storage area at different angles, and modulated by the information data written to the holographic medium. An optical modulation process for outputting the signal light, a reference light irradiation process for changing an incident angle of the reference light that interferes with the signal light with respect to the holographic medium, and sub-data obtained by dividing the information data into a plurality of pieces, A recording process for recording each of the recording areas into divided blocks, and an angle detection information writing process for writing angle detection information indicating an angle corresponding to the block for each block in which the sub-data is written. Features.
Thus, the holography recording apparatus / method records angle detection information for detecting the angle of the reference light corresponding to each block in the information data page for each block, so that the above information is obtained from the medium (holographic medium). When reproducing data, create a media that can detect the appropriate angle at the time of playback of each block by the above angle detection information even if there is a deviation in angular accuracy of the holographic playback device or an angular deviation in media loading. Can do.
Further, in the holographic recording device of the present invention, when the blocks are multiplexed with a predetermined angle pitch of the reference light, the angle for each block is detected based on the angle detection information, so that the access processing to the corresponding block is performed. This makes it easy to create a medium on which sub-data can be read at high speed.
Furthermore, the holographic recording device of the present invention encodes and records not only information for detecting the angle of the reference light of the information data page, but also incidental information such as the block number of each block and includes it in the angle detection information, A medium capable of efficiently accessing a desired block during reproduction can be created.

In the holographic recording device of the present invention, the angle detection information writing unit records the same reference light angle as the angle detection information with a plurality of adjacent blocks as a set in the block in which the sub-data is written.
In the holographic recording device of the present invention, the angle detection information writing unit divides the angle interval between the information data to be multiplexed corresponding to the number of blocks in the block in which the sub data is written, and the divided angle. The angle of the reference beam is recorded as the angle detection information for each block according to the interval.
As a result, the holographic recording apparatus of the present invention writes information for reproducing the sub-data for each block in which the sub-data is recorded, and reduces the accuracy of the loading of the medium and the angle of the reference beam during recording. It is possible to produce a medium on which information data is recorded at low cost.

In the holographic recording apparatus of the present invention, the angle detection information writing unit writes the angle detection information for each information data page to be angle multiplexed.
As a result, the holographic recording apparatus of the present invention writes the angle corresponding to the information data page on the medium as information for reproducing the sub data for each block in which the sub data is recorded. The accuracy requirement of the angle of light can be reduced, and a medium on which information data is recorded can be produced at low cost.

In the holographic recording device of the present invention, the angle detection information writing unit includes first angle information obtained by deviating the angle detection information in a negative angle direction with respect to the angle of the reference light of the block, and positive Writing is performed as the second angle information deviated in the angle direction.
As a result, the holographic recording apparatus of the present invention provides the angle detection information for detecting the angle of the reference light corresponding to each block in the information data page as the reference light angle in writing for each block. By recording with a deviation of this amount, the angle of the reference beam when reading the block can be easily detected from the angle detection information, and the sub-data is read from each block of the information data page with high accuracy Can be created.

In the holographic recording device of the present invention, the angle detection information writing unit records the angle detection information at a plurality of locations in the block in which the storage area is divided with respect to the angle change direction of the reference light.
As a result, the holographic recording apparatus of the present invention disperses the angle detection information at a plurality of locations as described above even if the angle detection information recorded at any location cannot be read due to some reading obstruction. Therefore, the angle of the reference light at the time of reading the block can be easily detected from the angle detection information from the angle detection information of the place where the reading is possible, and the sub-data is read from the block with high accuracy. Media can be created.

The holographic reproducing device of the present invention is different by sequentially changing the angle of the reference light applied to the holographic medium in which the sub-data obtained by dividing the information data is recorded in each of the plurality of blocks in which the storage area is divided. Reads out sub-data recorded at multiple angles and reproduces information data. Reference light irradiating means for irradiating the holographic medium with reference light at different angles, and emitting from the holographic medium by the reference light Recording angle detection means for detecting the detected angle detection information and controlling the angle of the reference light, and the reproduction light emitted from the block is made incident by the reference light, the sub data is detected from the reproduction light, and the information data is Data detection means for reproduction.
The holographic reproduction method of the present invention is different by sequentially changing the angle of the reference light to be irradiated on the holographic medium in which the sub-data obtained by dividing the information data is recorded in each of the plurality of blocks in which the storage area is divided. Reads sub-data recorded in multiple at an angle and reproduces information data, and irradiates the holographic medium with reference light at different angles and emits the reference light from the holographic medium. Recording angle detection process for detecting the detected angle detection information and controlling the angle of the reference light, the reproduction light emitted from the block is made incident by the reference light, the sub data is detected from the reproduction light, and the information data is And a data detection process for reproduction.
Accordingly, the holography reproducing device / method of the present invention reads out the angle detection information for detecting the angle of the reference beam corresponding to the information data page when reproducing the information data from the medium (holographic medium). Even if there is a deviation in the angular accuracy of the reference light used for reproduction or an angular deviation in the media loading, the angle detection information can detect an appropriate angle at the time of reproduction of each block in the information data page. The sub data can be read efficiently.
In addition, the holographic reproducing device of the present invention includes not only information for detecting the angle of the reference beam corresponding to the block from the angle detection information, but also auxiliary information such as the block number of the block in the information data page, By reading out each block number from the block and searching for this block number, it is possible to access a desired block and perform efficient reading processing of sub-data.

In the holographic reproduction device of the present invention, the recording angle detection means detects angle detection information recorded for each block, and adjusts the angle of the reference beam for each block.
As a result, when the blocks are multiplexed at a predetermined angular pitch of the reference light, the holographic reproducing device of the present invention detects the angle for each block based on the angle detection information, and adjusts the reference light to an appropriate angle. Therefore, access processing to the corresponding block is facilitated, and sub-data can be read at high speed.

In the holographic reproducing device according to the present invention, the recording angle detection means uses, as the angle detection information, first angle detection information obtained by deviating a negative angle from the reference light angle of each block, and a positive angle. The detected second angle detection information is detected, a sum component and a difference component of the first angle detection information and the second angle detection information are obtained, and the difference component is normalized by dividing by the sum component. The angle of the information data page is detected from the numerical value.
As a result, the holographic reproduction device of the present invention is stable because the difference component is normalized by the sum component even if the detection intensity (reproduction intensity) of the angle detection information changes in block units in the information data page due to some condition. Thus, the angle information of the reference light at the time of reading can be calculated.

In the holographic reproducing device according to the present invention, the recording angle detection unit records the storage area in the vicinity of two sides parallel to the angle change direction of the block in the block obtained by dividing the storage area with respect to the angle change direction of the reference light. The angle detection information is detected, and the first angle detection information in which the negative angle in the angle detection information is deviated for each side is combined with the second angle detection information in which the positive angle is deviated, A shift with respect to an angle change of each side is obtained as a first shift detection signal and a second shift detection signal, respectively, and a sum component and a difference component of the first shift detection signal and the second shift detection signal are determined, An angle shift between the two sides of the block is detected from a numerical value normalized by dividing the difference component by the sum component.
In the holographic reproduction device of the present invention, the recording angle detection unit detects an angle shift between two sides of the reference light for each block in which sub-data is recorded, and controls the angle of the reference light.
As a result, the holographic reproducing device of the present invention detects the angular deviation between the two sides of the block in which the sub-data is stored, so that the angle of the reference beam can be adjusted for each block, and the two-dimensional servo signal Thus, it is possible to reduce the accuracy requirement of the angle of the reference beam of the apparatus and the position of the medium in loading, and the apparatus can be manufactured at low cost.

In the holographic medium of the present invention, the sub-data obtained by dividing the information data page is recorded for each block obtained by dividing the recording area, and the angle detection information indicating the angle at which each sub-data is recorded is recorded when the information data is written. The angle is recorded with a predetermined amount of deviation with respect to the reference beam angle.
The holographic medium of the present invention reads out the angle detection information recorded in each block when reproducing the information data from the medium, so that the angle accuracy of the reference light used for reproduction is different or the angle in the medium loading. Even if there is a deviation, an appropriate angle at the time of reproduction can be detected for each block in the information data page from the angle detection information, and sub-data can be efficiently read from each block.
That is, in the holographic medium of the present invention, the angle detection information for detecting the angle of the reference light corresponding to each block in the information data page is predetermined for each block before and after the angle of the reference light in writing. Therefore, the angle of the reference beam when reading the information data page can be easily detected from the angle detection information during reproduction, and the information data can be read from the information data page with high accuracy. Can be done.

In the holographic medium of the present invention, the angle detection information is recorded in a plurality of locations inside and / or around the block in which the sub data is recorded.
As a result, the holographic medium of the present invention disperses the angle detection information at a plurality of locations as described above even when the angle detection information recorded at any location cannot be read due to some reading hindrance. Therefore, the angle of the reference light at the time of reading the information data page can be easily detected from the angle detection information based on the angle detection information of the location where the data can be read, and each information in the information data page can be detected with high accuracy. Sub data can be read from the block.

In the holographic medium of the present invention, the angle detection information is deviated in the negative angle direction with respect to the angle of the reference light of the sub data, and the second angle is deviated in the positive angle direction. It consists of information.
As a result, the holographic medium of the present invention is stable because the difference component is normalized by the sum component even if the detection strength (reproduction strength) of the angle detection information changes in block units in the information data page due to some condition. Thus, the angle information of the reference light at the time of reading can be calculated.

The holographic recording apparatus of the present invention changes the wavelength of the reference light applied to the holographic medium, multiplex-records information data for each predetermined storage area at different wavelengths, and is modulated by the information data written to the holographic medium. Optical recording means for outputting signal light; reference light irradiating means for changing the wavelength of reference light that interferes with the signal light with respect to the holographic medium; and sub-data obtained by dividing the information data into a plurality of recording areas. Recording means for recording in each of the divided blocks, and wavelength detection information writing means for writing wavelength detection information indicating the wavelength corresponding to the block for each block in which the sub-data is written.
The holographic recording method of the present invention changes the wavelength of the reference light applied to the holographic medium, multiplex-records information data for each predetermined storage area at different wavelengths, and is modulated by the information data written to the holographic medium. An optical modulation process for outputting signal light; a reference light irradiation process for changing a wavelength of reference light that interferes with the signal light with respect to the holographic medium; and sub-data obtained by dividing the information data into a plurality of the recording areas. And a wavelength detection information writing process for writing wavelength detection information indicating a wavelength corresponding to the block for each block in which the sub-data is written.
Accordingly, the holography recording apparatus / method records the wavelength detection information for detecting the wavelength of the reference light corresponding to each block in the information data page for each block, thereby recording the sub-data from the medium (holographic medium). When reproducing, a medium capable of detecting an appropriate wavelength at the time of reproduction can be created by the above-described wavelength detection information even if there is a deviation of the laser device in the holography reproducing apparatus.

The holographic reproducing device of the present invention is different by sequentially changing the wavelength of the reference light to be applied to the holographic medium in which the sub-data obtained by dividing the information data is recorded in each of the plurality of blocks in which the storage area is divided. Reads sub-data recorded in multiple at an angle and reproduces information data. Reference light irradiating means for irradiating the holographic medium with a reference light at a different wavelength; emitted from the holographic medium by the reference light Recording angle detection means for detecting the detected wavelength detection information and controlling the wavelength of the reference light, and the reproduction light emitted from the block is made incident by the reference light, the sub data is detected from the reproduction light, and the information data is Data detection means for reproduction.
The holographic reproduction method of the present invention is different by sequentially changing the wavelength of the reference light to be applied to the holographic medium in which the sub-data obtained by dividing the information data is recorded in each of the plurality of blocks in which the storage area is divided. Reads sub-data recorded at multiple angles and reproduces information data, and irradiates the holographic medium with reference light by irradiating the holographic medium with a reference light, and emits the reference light from the holographic medium. Recording angle detection process for detecting the detected wavelength detection information and controlling the wavelength of the reference light, and the reproduction light emitted from the block is made incident by the reference light, the sub data is detected from the reproduction light, and the information data is And a data detection process for reproduction.
Thus, the holography reproducing apparatus / method of the present invention reproduces the wavelength detection information for detecting the wavelength of the reference light corresponding to each block in the information data page when reproducing the sub-data from the medium (holographic medium). By reading, even if there is a deviation in wavelength accuracy of the holographic reproducing device, an appropriate wavelength at the time of reproduction can be detected from the wavelength detection information, and information data can be read efficiently.

In the holographic medium of the present invention, the sub-data obtained by dividing the information data page is recorded for each block obtained by dividing the recording area, and the angle detection information indicating the wavelength in which each sub-data is recorded is blocked when the information data is written. Are recorded with a predetermined amount of wavelength being deviated with respect to the wavelength of the reference light.
Accordingly, in the holographic medium of the present invention, the wavelength detection information for detecting the wavelength of the reference light corresponding to the block in the information data page is different from the wavelength of the reference light in writing for each block in each information data page. Since it is recorded with a predetermined amount of deviation before and after, the wavelength of the reference light at the time of reading each block can be easily detected from the wavelength detection information at the time of reproduction, and the sub-data from the block can be detected with high accuracy. Reading can be performed.

  As described above, the holographic recording apparatus / method of the present invention multiplexes the angle (or wavelength) of the reference light at a predetermined angle (wavelength) pitch for each information data page when recording information data on a medium. In this case, the angle (or wavelength) detection information for detecting the angle (or wavelength) of the reference light corresponding to the block in the angle (or wavelength) information data page is recorded for each block, thereby recording the medium (holographic medium). When reproducing the above-mentioned information data, even if there is a deviation in the angle (or wavelength) accuracy of the holography reproduction device or an angle deviation in the media loading, the angle (or wavelength) detection information is used for reproducing each block. Media that can detect the appropriate angle (or wavelength) can be created.

  Further, the holographic reproducing device / method of the present invention provides a reference beam corresponding to each block in an information data page when reproducing predetermined information data from a medium on which information data is multiplexed and recorded by the holographic recording device / method. The angle (or wavelength) detection information for detecting the angle (or wavelength) of the holography is read out when reproducing the information data from the medium (holographic medium), thereby shifting the angle (or wavelength) accuracy of the holography reproducing device. Even if there is an angle shift in media loading, the above angle (or wavelength) detection information can detect the appropriate angle (or wavelength) at the time of playback of each block, and the information data can be read efficiently. Can do.

Hereinafter, a holographic recording apparatus and a reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 (corresponding to the first recording method later) generates a plurality of pages for recording information data (hereinafter referred to as information data pages) by changing the angle of the reference light when multiple recording of information data is performed, It is a conceptual diagram which shows the concept of the holographic recording and reproducing method in the same embodiment in the case of performing the multiple recording of information data.
In the present invention, as shown in FIG. 1, in the recording area of a holographic medium (hereinafter referred to as a medium), the information data page to be multiplex-recorded is divided into a plurality of blocks.
That is, according to the present invention, when information data is recorded on a medium, the information data is divided into a plurality of sub-data, and the information data page is divided into N blocks (block B1 to block BN) in the same number as the division number N. ), And each of the divided sub-data is written in each of the divided blocks (block B1, block B2,..., Block BN). As shown in FIG. 1, for each block, angle detection information indicating the irradiation angle of the reference light when sub-data is written in the block is recorded by a record detection information writing unit 9 described later. .

This angle detection information is composed of a combination of the first angle detection information E and the second angle detection information L, and the outer peripheral portion or inner peripheral portion of the block obtained by dividing the recording area of the multiplex recorded information data page Or an angle detection information writing unit 9 (see FIG. 9), which will be described later, is written at a predetermined position (a preset position) inside the recording area.
Here, when the angle detection information is written, for example, in the outer peripheral portion and / or the inner peripheral portion of the recording area by a holographic recording device, a set of the first angle detection information E and the second angle detection information L is It is provided opposite to the side parallel to the Bragg diffraction direction.
Further, on the side parallel to the Bragg diffraction direction, the first angle detection information E and the second angle detection information L are respectively located at positions corresponding to the first angle detection information E and the second angle detection information L. Record.

The angle detection information includes first angle detection information E recorded by shifting (deviation) the angle in a predetermined negative direction with respect to the angle of the reference light for recording information data, and predetermined positive This is a combination with the second angle detection information L recorded by shifting (deviation) the angle in the direction of, and shifting the angle of, for example, about 1/4 of the angle pitch of the reference light in both the positive direction and the negative direction. Amount.
Therefore, the holographic reproducing device according to the present embodiment detects the angle detection information at the time of reproducing information data from the medium, and detects the angle pitch of the block in which the sub-data obtained by dividing the information data is recorded. The angle of the reference light used for reading can be easily controlled.

Hereinafter, the flow of the detection processing of the angle of the reference light corresponding to the information data page from the angle detection information described above will be described with reference to FIG. The reference light angle detection process and reference light angle control at the time of reading based on the angle detection information described below are performed in a recording angle detection unit 10 (see FIG. 9) described later.
Each angle detection information corresponds to a change in the angle of the reference light during reproduction, and the first angle detection information E and the second angle detection information L are detected by the detector (detector) as peaks having different detection intensities. Detected.

Here, assuming that the detection intensity of the first angle detection information E detected by the detector is e and the detection intensity of the second angle detection information L is l, the following equation (1) is calculated.
PES = (e−l) / (e + l) (1)
In FIG. 2, when detecting the angle θ11 of the reference light for reading (corresponding to the block B1 on the first page of the information data page), the detection intensity e11 of the first angle detection information E11 and the second angle detection information L11 The PES is calculated using the detected intensity l11.

That is, the difference component between the detection intensity e11 of the first angle detection information E11 and the detection intensity l11 of the second angle detection information L11 is obtained by the above equation (1), and the sum component of the detection intensity e11 and the detection intensity l11 is obtained. The PES is calculated by dividing and normalizing the difference component by the sum component.
As a result, even if the detection intensity of the angle detection information (reproduction intensity S11) changes in units of blocks in the information data page due to some condition, the difference component is normalized by the sum component, and the PES can be calculated stably. it can.

In the above equation (1), PES (Page Error Signal) is a numerical value indicating a deviation amount (error amount at an access position) from each information data page.
Then, in the negative slope portion of the PES, the point A at which the zero (0) cross is made, that is, the angle at which “el” is “0” is the angle of the reference light for reading the information data in each information data page. The angle of the reference light for reading corresponds to the angle θ of the reference light when writing the information data page, and the reproduction intensity (diffraction efficiency) S of the recorded information data in the detector is maximized.
That is, it is possible to detect the angle θ11 of the reference light corresponding to each block B11, B12, B13, B14,... That maximizes the reproduction intensity S11 of each block on the first page of the predetermined information data page.
Further, it is possible to detect the angle θ21 of the reference light corresponding to each block B21, B22, B23, B24,... That maximizes the reproduction intensity S21 of each block on the second page of the information data page.

Therefore, the PES can be used for servo control to access each block of the information data page, that is, to adjust the angle of the reference light for reading, when reading the information data recorded on each information data page.
In addition, as described above, the angle detection information is recorded around the area corresponding to the block of the recording area where the sub-data obtained by dividing the information data is recorded, or in the area corresponding to the block of the recording area. You may record in the preset position inside.
Furthermore, by recording the angle detection information in a plurality of locations instead of one location (distributed recording), even if any location is not detected, using the read angle detection information in a plurality of locations, The angle of the reference light corresponding to the block can be calculated.

That is, as shown in the following equation (2), the PES is calculated by calculating the sum of the detection intensity e of the first angle detection information E and the detection intensity l of the second angle detection information L. Thus, it can be used for servo control for adjusting the angle of the reference light for reading.
PES = (Σe−Σl) / (Σe + Σl) (2)
At this time, the combination of the angle detection information, that is, the arrangement of the first angle detection information E and the second angle detection information L is made different as shown in FIG. Thereby, the accuracy of the angle of the reference beam corresponding to the information data page can be improved.
As described above, the angle detection information is recorded for each block of each information data page, thereby detecting the angle of the reference light when reading the sub-data obtained by dividing the information data stored in each block. Can do.

In addition, in the angle detection information to be recorded in each block, the record detection information writing unit 9 records the same angle detection information in all the blocks of the information data page, and for each block in the information data page In addition, there is a second recording method for recording each incident angle of the reference light when sub-data is recorded in the block.
In the first recording method, sub-data is recorded at the same reference light angle in each block included in each information data page, and the first angle detection information E is also referred to when recording on the information data page. Similarly, the second angle detection information L is recorded with an angle having the same positive deviation amount with respect to the incident angle. .

Further, when reproducing information data, angle detection information is obtained for each block in which each sub-data is recorded.
In the recording of information data on the medium, ideally, the sub-data should be recorded at the same incident angle of the reference light for all the blocks in the information data page.
However, the angular position where the signal intensity is maximized may be shifted due to the angular accuracy of the reference light of the holographic recording apparatus or the distortion of the media.
Therefore, as shown in FIG. 3A, the exposure start time for detecting the light reproduced by irradiating the reference light with the detector 6 is adjusted for each block by shifting the incident angle of the reference light for each sub-data. Then, it may be played back.

On the other hand, in the second recording method, as shown in FIG. 4, the recording angle of the sub data is divided by dividing the angular interval of the information data data page into a number equal to the number of blocks so as to be equal, for example. Let the angle pitch be the block angle.
Then, the angle detection information of each block is recorded as the first angle detection information E according to the angle of the reference light of the immediately preceding block, and the second angle detection information L is recorded immediately after in the continuous block row in the information data page. It is recorded by the angle of the reference beam of the block.
Therefore, information on the reference light at the time of recording is recorded for each block so as to detect the angle of the reference light on which the sub data is recorded for each block.

That is, the angle of the reference beam corresponding to each block B11, B12, B13, B14,..., Which maximizes the reproduction intensity S11, S12, S13, S14,. θ11, θ12, θ13, θ14,..., θ1N can be detected.
Here, the angle of the reference light when the sub-data is recorded, the angle of the reference light when the first angle detection information E is recorded, and the second angle detection information L are stored in each block. The angle of the reference light at the time of recording is in a positional relationship that is shifted from each other.
However, paying attention to each sub-data, the state of multiplexing between information data pages and the relationship between the angle detection signals are the same as in FIG.

At the time of reproduction, as shown in FIG. 3B, the sub data is sequentially read out according to the angle of the reference light when each block is recorded.
At this time, the recording angle detection unit 10 detects the deviation of the angular position by the equation (1) or (2) so that the reproduction intensity S becomes the maximum, and the control similar to FIG. For each block (blocks B11, B12, B13, B14), the angle of the reference beam is corrected and the sub-data recorded in each block is reproduced.
At this time, since the previous block does not exist for the block B11, as shown in FIG. 4, the first angle detection information E11 is recorded by extending to the angle area where the information data is not recorded.

Further, in the second recording method, the recording angle detection unit 10 obtains angle detection information arranged on both sides of the area corresponding to each block, a combined signal at each side, and obtains left side angle detection information U and right side Angle detection information V is generated.
Here, for example, the detection intensity u of the left side angle detection information U is equal to the detection intensity e of the first angle detection information E on the left side and the second angle detection information L of each block as shown in FIG. It is a value obtained by adding the detection intensity l.
Similarly, the detection intensity v of the right side angle detection information V is a value obtained by adding the detection intensity e of the first angle detection information E on the right side and the detection intensity 1 of the second angle detection information L.

  Then, the recording angle detection unit 10 uses the detection intensity u and the detection intensity v to normalize the difference component (v−u) by the sum component (v + u) in the following equation (3), A balance signal DES for detecting a deviation angle φ of each side from the detection axis perpendicular to the Bragg diffraction direction, that is, a deviation from a recording angle in the non-Bragg direction (direction perpendicular to the Bragg diffraction direction) on the opposite side is calculated ( (See FIG. 6). Here, φ indicates a deviation from the angle θ of the reference light when PES is minimized, and φ0 is substantially “0”.

  DES = (v−u) / (v + u) (3)

Here, a waveform in which the peak positions of the balance signal DES are shifted in opposite directions at a shift angle φ in the non-Bragg direction with respect to the detection axis of each side of the block parallel to the Bragg diffraction direction due to the distortion state of the medium. It becomes.
Using this balance signal DES, it is possible to detect the angular deviation of the side parallel to the Bragg diffraction direction.
Then, the recording angle detection unit 10 determines the point B that becomes a zero (0) cross, that is, the angle at which “v−u” is “0” in the inclined portion near the center of the DES, in the information data page. An angle in the non-Bragg direction of the reference light for reading is set.
The angle of the reference light for reading minimizes the shift angle φ of the reference light when writing the information data page, and maximizes the reproduction intensity (diffraction efficiency) S of the recorded information data in the detector.

That is, the angle of the reference beam corresponding to each block B11, B12, B13, B14,..., Which maximizes the reproduction intensity S11, S12, S13, S14,. In each of θ11, θ12, θ13, θ14,..., the deviation angle φ in the non-Bragg direction can be detected.
Specifically, as shown in FIG. 7A, the angular deviation of the reference light in the non-Bragg direction due to the distortion of the media on each side (side parallel to the Bragg diffraction direction) in each block is shown in FIG. As shown in FIG. 5, it is possible to detect the angle deviation of each side with respect to the detection axis for each block, correct the angle of the reference light that minimizes DES, and reproduce the image at the optimum reproduction position.

As shown in FIG. 8, the angle detection signal can be extended to an angle region that does not include information data.
That is, when reproducing the information data, when the block of each information data page is detected by sweeping the angle of the reference beam, as shown in FIG. It is also possible to record angle information data by extending to an angle region where no is recorded.
In this case, the angle θ0 one page before is detected with respect to the angle of the reference light at which the information data is actually written, that is, the first information data page (reference light angle θ1) which is the actual first page. Therefore, the angle θ1 of the reference light of the first information data page can be roughly estimated from the angle θ0 based on the angle pitch of the reference light corresponding to the information data page set in advance in advance.

As a result, the recording angle detection unit 10 to be described later, when continuously reproducing each information data page, sets the position where the angle pitch is added to the angle θ of the reference light of the immediately preceding information data page as the next information data page. The angular position of the reference light corresponding to the original information data page is corrected from the deviation value of the PES signal calculated at that time, and the mirror 8 is controlled according to the angle. Since it can be reflected in the prediction of the information data page, servo control of the angle of the reflecting surface of the mirror 8 can be easily performed.
Thus, continuous and high-speed information data can be reproduced in the holographic reproduction processing according to the present invention.

<First Embodiment>
Next, a holographic recording / reproducing apparatus according to the first embodiment of the present invention will be described with reference to FIG. FIG. 9 is a block diagram showing a configuration example of the holographic recording / reproducing apparatus according to the first embodiment. That is, FIG. 9 is an optical layout diagram showing a configuration example for recording and reproducing on a medium.
In the first embodiment of FIG. 9, a transmission hologram in which signal light and reference light are incident on the medium 4 from the same side is described as an example.
The holographic recording / reproducing apparatus shown in FIG. 9 includes shutter 1, SLM, 2, FT lens 3 and 5, detector 6, shutter 7, mirror 8, angle detection information writing unit 9, recording angle detection unit 10, and not shown. It has a laser light source.

A. Recording process of information data on the medium 4 The laser light source emits a laser beam having a predetermined wavelength, and this laser beam is divided into a distribution light M and a distribution light N by a predetermined mechanism (such as a beam splitter (not shown)), The light enters the shutter 1 and the shutter 7, respectively.
The shutter 1 is opened when information data is written to the medium 4, and is closed when not written.

The SLM 2 is composed of a liquid crystal panel or the like, and displays a checkered dot pattern corresponding to information data to be written on the medium 4, that is, two-dimensional information data to be written, on a modulation surface perpendicular to the incident angle of the distribution light M. To form.
The SLM · 2 modulates the intensity of the incident distributed light M by the dot pattern on the modulation surface, and emits the signal light including information to be written on the medium 4 to the FT (Fourier transform) lens 3.

In addition, the SLM · 2 associates the angle detection information (first angle detection information E and second angle detection information L) with the writing position of the angle detection information at the writing timing of each angle detection information. It is formed on the modulation surface at a different timing from the information data.
Although a transmissive SLM is used in FIG. 9, a reflective SLM can be used in combination with a beam splitter or the like.
In addition, the SLM.2 is efficient in that it has a wider modulation surface (modulation region) so that the whole including the information data and the angle detection information can be controlled.

In FIG. 1, the entire surface including the area where information data and angle detection information (and wavelength detection information described later) are recorded is displayed in white.
However, in practice, on the modulation surface, for example, it is preferable that the modulation is made black so that the portion where the data is “0” does not transmit the reference light, and the portion where the data is “1” transmits the reference light. In addition, when recording angle detection information by shifting the angle, only the corresponding angle detection information is displayed at a predetermined position where the angle is shifted, and the reference light is transmitted to the storage position of the angle detection information on another information data page. In order to avoid this, the recording is made black (without transmitting light).
Furthermore, when the sub data is recorded at a position corresponding to each block in the recording area, the angle detection data portion may be recorded in black.

The FT lens 3 collects the signal light from the SLM 2 and irradiates the medium 4 to be hologram-recorded (multiplexed recording). Here, the medium 4 is installed in the vicinity of the condensing point of the FT lens 3.
The shutter 7 controls the emission of the distributed light N distributed by the beam splitter to the mirror 8 by performing an opening / closing process synchronized with the opening / closing timing of the shutter 1.

  The mirror 8 is composed of a galvanometer mirror or the like that can vary the reflection angle of incident light, and the reflection angle of the incident distributed light N is sequentially changed by the control of the angle detection information writing unit 9 so that the medium is used as reference light. 4 is emitted.

Here, the reference light is controlled to be incident so that the signal light is overlapped in the vicinity where the signal light is incident on the medium 4, and information on interference fringes formed by the interference between the signal light and the reference light is information data (each Sub-data) in the block).
At this time, the mirror 8 changes the angle of the reference light at a predetermined angle pitch, so that information data of different signal lights is recorded in a predetermined storage area of the medium 4, that is, the SLM 2 New data can be sequentially overwritten by two-dimensional information data of different dot patterns (checkered pattern) formed on the modulation surface.

The angle of the reference beam in which the two-dimensional information data is recorded is called an information data page.
In the above-described writing process, in the case of the first recording method already described, the angle detection information writing unit 9 sets the reference light writing angle for each block in each information data page in units of the block angle. For each reference light angle corresponding to each block, the mirror is adjusted to a negative angle by an angle amount that is 1/4 of the angle pitch of the information data page with respect to the reference light angle corresponding to this information data page. 8 is adjusted, the first angle detection information E is recorded at a predetermined position corresponding to each block in the recording area, and after sub-data is written in the block, the angle amount is 1/4 of the angular pitch. The reflection surface of the mirror 8 is adjusted to a positive angle, and the second angle detection information L is recorded at a predetermined position corresponding to each block in the recording area.

At this time, the angle detection information writing unit 9 adjusts the reflection surface of the mirror 8 to a negative angle by an angle amount that is ¼ of the angle pitch with respect to the angle of the reference light corresponding to each information data page. When the first angle detection information E is output to the SLM · 2 and the reflecting surface of the mirror 8 is adjusted to a positive angle by an angle amount that is ¼ of the angle pitch, the second angle detection information L is changed to the SLM · Output to 2.
As a result, the SLM · 2 forms the first angle detection information E and the second angle detection information L as dot patterns at the positions of the modulation surfaces corresponding to the writing positions in the medium 4, respectively.

  On the other hand, in the case of the second recording method, the angle detection information writing unit 9 adjusts the writing angle of the reference light of each block in the information data page in units of the block angle and the reference corresponding to each block. For each light angle, the reflection surface of the mirror 8 is adjusted to a negative angle (that is, an angle corresponding to the immediately preceding block) by an angle amount of the block angle with respect to the reference light angle corresponding to this information data page. After the first angle detection information E is recorded at a predetermined position corresponding to the block in the recording area and the sub data is written, the mirror is mirrored to a positive angle (an angle corresponding to the immediately following block) by the angle amount of the block angle. 8 is adjusted, and the second angle detection information L is recorded at a predetermined position corresponding to the block of the recording area.

At this time, when the angle detection information writing unit 9 adjusts the reflection surface of the mirror 8 to a negative angle by the angle amount of the block angle with respect to the angle of the reference light corresponding to each information data page, When the angle detection information E is output to the SLM · 2 and the reflection surface of the mirror 8 is adjusted to a positive angle by the amount of the block angle, the second angle detection information L is output to the SLM · 2.
As a result, the SLM · 2 forms the first angle detection information E and the second angle detection information L as dot patterns at the positions of the modulation surfaces corresponding to the writing positions in the medium 4, respectively.
At this time, when the first angle detection information E and the second angle detection information L are recorded, the recording / reproduction efficiency of the hologram can be improved by recording simultaneously with the sub-data of the adjacent block.

Further, in the first and second recording methods, angle detection information recorded for each block of each information data page is encoded as shown in FIG. 10, and block information of the corresponding block, for example, a page of each information data page Numbers and block numbers may be recorded in advance.
By including such information, the angular position of the block in the information data page can be detected, and information such as the page number of the information data page and the block number of the block can be detected at the same time. Enables more reliable and flexible data access.

The above-described encoding may be in the form of a one-dimensional barcode pattern shown in FIG. 10A for easy reading, and the two-dimensional shown in FIG. 10B for the purpose of increasing the amount of information. A dot pattern may be used.
In addition, the angle detection information pattern does not necessarily have to be the same decomposition dot pattern as the information data (sub-data), and it is possible to easily read and detect the code by reducing the dot resolution.

In the multiplex recording method described above, the medium 4 is a hologram medium having a relatively thick recording layer (a layer in the thickness direction where interference fringes are formed) (for example, 1 mm or more), and the angle of the reference light is multiplexed. When recording, the angular resolution at the angular pitch of the information data page is determined by the wavelength λ of the laser light, the incident angle θ of the signal light and the reference light with respect to the surface of the medium 4, and the thickness D of the medium 4.
That is, the angular resolution at the angular pitch is proportional to the laser wavelength λ and inversely proportional to the thickness D of the medium 4.
Here, the incident angle θ is an angle formed by the reference light incident direction with respect to the vertical axis P of the reference light incident surface of the medium 4.

B. Next, when reproducing information data recorded on the medium 4, the signal light side shutter 1 is closed, the reference light side shutter 7 is opened, and only the distribution light N is obtained. By making the light incident on the medium 4, the information data recorded on the medium 4 is reproduced.
Based on the angle detection information written by the angle detection information writing unit 9, the recording angle detection unit 10 detects the angle of the reference light at the time of reading corresponding to the angle of the reference light at the time of recording. The sub data corresponding to each block of the information data page is reproduced and emitted as reproduction light from the back surface of the medium 4 (the surface opposite to the surface on which the reference light is incident) to the FT lens 5.

The FT lens 5 returns the incident reproduction light to signal light incident on the FT lens 3, that is, returns to parallel light (coherent light), and projects it onto a detector (detector) 6.
Here, the focal lengths of the FT lens 3 and the FT lens 5 are the same, and the SLM · 2, the FT lens 3, the media 4, the FT lens 5, and the detector 6 are arranged apart from each other by the focal length.
In other words, the SLM 2 and the detector 6 are respectively placed at the front focal point of the FT lens 3 and the rear focal point position of the FT lens 5.

Therefore, the reference light is diffracted by the sub-data stored in each block of the information data page in the recording area of the medium 4, that is, interference fringes, and the reproduction light is generated.
The reproduced light is converted into a parallel component by the FT lens 5 and imaged on the detector 6 as a pattern similar to the two-dimensional dot pattern on the modulation surface of the SLM 2 and recorded in each block. Is played.
The detector 6 is composed of a two-dimensional CCD, a C-MOS image sensor or the like, reads the pattern, and outputs it as information data to an external circuit.

Here, the recording angle detection unit 10 adjusts the angle of the reflecting surface of the mirror 8 and controls the angle θ of the reference light incident on the medium 4 to thereby store the sub-data stored in each block of different information data pages. Can be played.
For this reason, the recording angle detection unit 10 reads the detection intensities e and l of the angle detection information in which the arrangement position is set in advance from the detector 6, and performs the processing of the expression (1) or (2) (and further necessary The angle θ of the reference light is detected so that the PES is “0” at a negative inclination, and the angle of the reflecting surface of the mirror 8 is adjusted so as to be the angle θ. Servo control is performed.

The reproduction intensity S of the reproduction signal light observed when the angle of the reference light is continuously changed is schematically shown in FIG. 2 (first recording method) and FIG. 4 (second recording method). .
The intensity of the reproduction light of the sub data stored in the block of each information data page shows a distribution approximated by the square of the approximate SINC function (SIN (πX) / πX) with respect to the angle θ of the reference light. Yes.
For this reason, the blocks of each information data page are arranged with each other so that the centers of adjacent blocks come near the second zero point of the SINC function. Can be efficiently read with high accuracy.
In the subsequent circuit, the sub-data output from the detector 6 is connected in time series, and the sub-data is combined with the information data.

Ideally, if the angle of the reference light at the time of recording can be reproduced at the time of reproduction and the reference light can be incident at that angle, the maximum diffraction efficiency from the interference fringes of the block in the information data page to be read out of the recording area And the maximum reproduction intensity S on the detector 6 is obtained.
However, when the medium 4 is once taken out and loaded, when the medium 4 is tilted and fixed at the time of reinsertion, or when the loaded medium is recorded by another holography recording device, the medium is fixed. Cannot be set to the same angle as during recording.

For this reason, the angle of the reference light at the time of writing cannot be reproduced at the time of reproduction, and it is difficult to reproduce the information data written on the medium.
In particular, in a medium with high multiplicity having a thickness exceeding 1 mm, the angle pitch between information data pages is on the order of 0.1 degree, and the angle accuracy required at the time of reproduction is about 0.01 degree. Therefore, even if there is a slight angle shift of the optical system or an angle shift at the time of loading the medium, it is impossible to reproduce at the same angle.
However, as described above, in the present invention, the angle of reference light corresponding to each information data page can be detected by the recording angle detection unit 10 based on the angle detection information recorded on the medium. Even when the medium is loaded at an angle, the angle of the reflecting surface of the mirror 8 can be adjusted so that the angle of the reference light corresponding to each block of the information data page is successively obtained.

<Second Embodiment>
Next, as a second embodiment, a system configuration corresponding to a ROM (read only memory) type or a write-once type medium in which a holographic recording device and a holographic reproducing device are separated may be employed.
For example, in the system configuration shown in FIG. 11, signal light and reference light are incident from the opposite side of the medium 4 during recording (FIG. 11A), and the reference light is used as phase conjugate reproduction illumination light during reproduction. A reflection hologram is taken as an example (FIG. 11B).

In the case of the configuration shown in FIG. 11, in the holographic recording apparatus shown in FIG. 11A, the angle of the reference beam is changed, and the medium 4 on which the information data is multiplexed and recorded for a plurality of information data pages is used as the holography ROM. create.
Here, as in FIG. 9, the signal light is emitted from the SLM 2, the reference light is emitted from the mirror 8, and in other configurations, the recording angle detection unit 10 is not provided, and the FT lens 3 is the SLM 2. It is the same as that of FIG. 9 except arrange | positioning at the front part. A rectangular opening 11 is provided between the SLM 2 and the medium 4.
And the writing process of the information data and the angle detection information to the medium 4 is performed by the same process as in the first embodiment.
At this time, the reference light is incident on the recording area where the incident light is incident on the medium 4 from the surface opposite to the surface on which the signal light is incident.

Then, in the holographic reproducing device shown in FIG. 11B, at the time of reading, the phase conjugate reproducing illumination light is used instead of the reference light, and the information data reproducing process is performed by the reading process described in the first embodiment. .
In this holographic reproducing device, phase conjugate reproduced illumination light is incident on the same surface as the surface on which signal light is input in the holographic recording device. Thereby, it is not necessary to provide an FT lens on the holography reproducing device side.
Since the phase conjugate reproduction illumination light is configured to be read from behind, it is defined so that the reference light becomes phase conjugate light, and is the same beam as the reference light in FIG.

At this time, the angle of the phase conjugate reproduction illumination light is controlled by the recording angle detection unit 10 detecting the incident angle θ of the phase conjugate reproduction illumination light based on the angle detection information as in the first embodiment. The reflection surface of the mirror 8 is controlled so that the phase conjugate reproduction illumination light is incident at an angle corresponding to the information data page.
Although the holographic reproduction device is not shown, a laser device, a shutter 7, a mirror 8, and a recording angle detection unit 10 are provided as necessary as in the first embodiment.
The difference from the first embodiment is that the detector 6 is the same as the surface of the medium 4 to which the phase conjugate reproduction illumination light is input via the rectangular opening 12 (the area corresponding to the detection surface of the detector 6). It is arranged on the side.

Accordingly, the holographic reproducing device shown in FIG. 11B is a holographic ROM reproducing device that makes phase conjugate reproduction illumination light incident from a desired angle based on angle detection information recorded on the medium 4 and reproduces recorded information data. It can be.
In the above-described holographic ROM reproducing device, it is difficult to make the angle of the reference light at the time of writing and the angle of the phase conjugate reproducing illumination light at the time of reading particularly the same in the configuration. Assuming that different media are loaded, angular deviation is inevitable.
However, as described above, by recording the angle information number on the medium by the method shown in the second embodiment, it is possible to reproduce the information data accurately while allowing the angle deviation.

<Third Embodiment>
Next, a holographic recording / reproducing apparatus according to the third embodiment of the present invention will be described.
In the first and second embodiments, as described above, the information data in each storage area is multiplexed by generating the information data page for each different angle by changing the angle of the reference light. .
On the other hand, the third embodiment is an example applied to a wavelength multiplexing system that controls the laser light source, changes the wavelength of the emitted laser light, and multiplexes each wavelength.
However, in general, the wavelength resolution of transmission holograms is significantly inferior to that of reflection holograms. Therefore, in the case of multiplexing by wavelength, the reflection hologram method, that is, the phase conjugate light of the second embodiment is used. A configuration example in which the information signal is reproduced by using is preferable.

However, in either case of using a transmission hologram or a reflection hologram, the recording process in the third embodiment is not to shift the angle by setting the angle θ in the first and second embodiments to the wavelength λ. Instead, the information data is multiplexed and recorded by a plurality of information data pages by shifting the wavelength for each information data page.
On the other hand, in the reproduction processing in the third embodiment, the angle in the first and second embodiments is set as the wavelength, the recording angle detection unit 10 is changed to read the wavelength information data recorded on the medium by the recording wavelength detection unit, As in the first and second embodiments, the PES is calculated, the wavelength corresponding to the desired information data page is detected, the laser device is controlled to become this wavelength, and the information data page corresponding to this wavelength Read sub-data of each block at. (See Figure 12)

Here, the wavelength detection information is composed of a combination of the first wavelength detection information E and the second wavelength detection information L, and the first wavelength with respect to the wavelength of the reference light for recording the information data. The detection information E is recorded by shifting (deviation) the wavelength in a predetermined negative (short) direction, and the second wavelength detection information L is shifted (deviation) in the predetermined positive (long) direction. Are recorded.
Then, in both the positive direction and the negative direction, as a method similar to the first recording method in the first embodiment, the wavelength is about 1/4 of the wavelength pitch of the information data page of the reference light, for example, 1/4 or less. As a method similar to the second recording method in the first embodiment, the wavelengths of the immediately preceding and following blocks are set.

In addition, as described in the first and second embodiments, the method for extending the wavelength detection information and adding the page number and the method for encoding the wavelength detection information are applied in the same manner as in the case of angle multiplexing. Is possible.
In wavelength multiplexing, the temperature of the VCSEL or the like is controlled to change the wavelength of the emitted laser light, so it is difficult to set a control reference beyond the angle, and the method using the wavelength detection information in the present invention is as follows. This is effective as a method of reading information data recorded in each information data page.

Indicates the recording position of angle (or wavelength) detection information indicating the angle (or wavelength) of reference light with respect to each block in the multiplex recorded information data page in the first and second (or third) embodiments of the present invention. It is a top view of a medium. It is a conceptual diagram explaining the detection method of the angle of the reference light corresponding to each block of the information data page by which angle multiplexing recording was carried out in the 1st recording method of the 1st Embodiment of this invention. It is a conceptual diagram which shows the method of adjusting the angle shift | offset | difference of the Bragg diffraction direction (block division direction of an information data page) of reference light for every block. It is a conceptual diagram explaining the detection method of the angle of the reference light corresponding to each block of the information data page by which angle multiplexing recording was carried out in the 2nd recording method of the 1st Embodiment of this invention. In the multiple-recorded information data page in the first and second (or third) embodiments of the present invention, the axes perpendicular to the Bragg diffraction direction of the reference light on each of two sides parallel to the Bragg diffraction direction of each block FIG. 3 is a plan view of a medium showing a recording position of detection information indicating an angle (wavelength) deviation from reference light in FIG. 5 is a waveform illustrating processing for detecting an angle (wavelength) shift from the reference light on an axis perpendicular to the Bragg diffraction direction of the reference light on each of two sides parallel to the Bragg diffraction direction of each block using the detection information of FIG. FIG. Concept for explaining processing for detecting an angle (wavelength) shift from reference light on an axis perpendicular to the Bragg diffraction direction of the reference light on each of two sides parallel to the Bragg diffraction direction of each block using the detection information of FIG. FIG. It is a conceptual diagram at the time of recording an angle (or wavelength) detection signal extended to an angle where no information data is recorded. 1 is a block diagram illustrating a configuration example of a holographic recording / reproducing apparatus according to a first embodiment of the present invention. It is a conceptual diagram which shows the pattern shape at the time of encoding angle (or wavelength) detection information. It is a conceptual diagram explaining the holography recording device and holography reproducing | regenerating apparatus in the 2nd Embodiment of this invention. In the 3rd Embodiment of this invention, it is a conceptual diagram explaining the detection of the wavelength corresponding to an information data page from wavelength detection information.

Explanation of symbols

1,7 ... Shutter 2 ... SLM
3, 5 ... FT lens 4 ... Media 6 ... Detector 8 ... Mirror 9 ... Angle detection information writing unit 10 ... Recording angle detection unit 11, 12 ... Rectangular opening

Claims (21)

A holographic recording device that changes the angle of reference light applied to a holographic medium and multiplex-records information data for each predetermined storage area at different angles,
A light modulating means for outputting signal light modulated by information data written to the holographic medium;
Reference light irradiating means for changing the incident angle of the reference light that interferes with the signal light with respect to the holographic medium;
Recording means for recording the sub-data in which the information data is divided into a plurality of blocks into which the recording area is divided, and
An holography recording apparatus comprising: angle detection information writing means for writing angle detection information indicating an angle corresponding to the block for each block in which the sub data is written.   2. The angle detection information writing unit according to claim 1, wherein, in a block in which sub-data is written, the angle of the same reference light is recorded as the angle detection information with a plurality of adjacent blocks as a set. Holographic recording device.   The angle detection information writing means divides the angle interval between the multiplexed information data in a block in which sub-data is written, corresponding to the number of blocks, and refers to each block by the divided angle interval The holographic recording apparatus according to claim 1, wherein an angle of light is recorded as the angle detection information.   2. The holographic recording apparatus according to claim 1, wherein the angle detection information writing unit writes the angle detection information for each information data page to be angle multiplexed.   The angle detection information writing means has a first angle information obtained by deviating the angle detection information in the negative angle direction with respect to the angle of the reference light of the block, and a second obtained by causing the angle detection information writing means to deviate in the positive angle direction. The holographic recording apparatus according to claim 1, wherein the holographic recording apparatus is written as angle information.   The angle detection information writing unit records the angle detection information in a plurality of locations of the block in a block in which the storage area is divided with respect to the angle change direction of the reference light. Item 6. The holographic recording device according to any one of Items 5. Sub-data recorded in multiple angles at different angles by sequentially changing the angle of the reference light applied to the holographic medium in which the sub-data obtained by dividing the information data is recorded in each of the plurality of blocks in which the storage area is divided. Is a holographic reproduction device that reproduces information data,
Reference light irradiating means for irradiating the holographic medium with reference light at different angles;
Recording angle detection means for detecting angle detection information emitted by the reference light from the holographic medium and controlling the angle of the reference light;
A holography reproducing apparatus comprising: data detecting means for reproducing light emitted from the block by reference light, detecting sub-data from the reproduced light, and reproducing information data.   8. The holographic reproducing apparatus according to claim 7, wherein the recording angle detecting means detects angle detection information recorded for each block and adjusts the angle of the reference light for each block.   The recording angle detection means, as the angle detection information, first angle detection information in which a negative angle is deviated from the angle of the reference light of each block, and second angle detection in which a positive angle is deviated Information, the sum component and the difference component of the first angle detection information and the second angle detection information are obtained, and the angle of the information data page is obtained from the normalized numerical value obtained by dividing the difference component by the sum component. The holographic reproducing device according to claim 7, wherein the holographic reproducing device is detected.   The recording angle detection means detects the angle detection information recorded in the vicinity of two sides parallel to the angle change direction of the block in the block in which the storage area is divided with respect to the angle change direction of the reference light, The first angle detection information obtained by deviating the negative angle in the angle detection information for each side and the second angle detection information obtained by deviation of the positive angle are combined, and the deviation of each side with respect to the angle change is synthesized. The first deviation detection signal and the second deviation detection signal are respectively obtained, the sum component and the difference component of the first deviation detection signal and the second deviation detection signal are obtained, and the difference component is divided by the sum component. 9. The holographic reproducing device according to claim 7, wherein an angle shift between the two sides of the block is detected from a numerical value normalized by the method.   11. The recording angle detection unit controls an angle of the reference light by detecting an angle shift between two sides of the reference light for each block in which sub-data is recorded. Holographic playback device.   Sub-data that divides the information data page is recorded for each block that divides the recording area, and angle detection information that indicates the angle at which each sub-data is recorded is before and after the reference light angle of the block when writing the information data The holographic medium is recorded with a predetermined amount of angle deviation.   13. The holographic medium according to claim 12, wherein the angle detection information is recorded in a plurality of locations inside and / or around a block in which sub data is recorded.   The angle detection information includes first angle information deviated in a negative angle direction and second angle information deviated in a positive angle direction with respect to the angle of the reference light of the sub data. The holographic medium according to claim 12 or 13. A holographic recording device that changes the wavelength of reference light applied to a holographic medium and multiplex-records information data for each predetermined storage area at different wavelengths,
A light modulating means for outputting signal light modulated by information data written to the holographic medium;
Reference light irradiation means for changing the wavelength of the reference light that interferes with the signal light with respect to the holographic medium;
Recording means for recording the sub-data in which the information data is divided into a plurality of blocks into which the recording area is divided, and
A holography recording apparatus comprising: wavelength detection information writing means for writing wavelength detection information indicating a wavelength corresponding to the block for each block in which the sub data is written. Sub-data that is multiplexed and recorded at different angles by sequentially changing the wavelength of the reference light applied to the holographic medium in which the sub-data obtained by dividing the information data is recorded in each of the plurality of blocks in which the storage area is divided. Is a holographic reproduction device that reproduces information data,
Reference light irradiating means for irradiating the holographic medium with reference light at a different wavelength;
Recording angle detection means for detecting wavelength detection information emitted by the reference light from the holographic medium and controlling the wavelength of the reference light;
A holography reproducing apparatus comprising: data detecting means for reproducing light emitted from the block by reference light, detecting sub-data from the reproduced light, and reproducing information data. It is a holographic recording method in which the angle of the reference light applied to the holographic medium is changed, and information data is multiplexed and recorded for each predetermined storage area at different angles.
A light modulation process for outputting signal light modulated by information data written to the holographic medium;
A reference light irradiation process for changing an incident angle of the reference light that interferes with the signal light with respect to the holographic medium;
A recording process for recording the sub-data obtained by dividing the information data into a plurality of blocks into which the recording area is divided, and
A holography recording method comprising: an angle detection information writing step of writing angle detection information indicating an angle corresponding to the block for each block in which the sub data is written. Sub-data recorded in multiple angles at different angles by sequentially changing the angle of the reference light applied to the holographic medium in which the sub-data obtained by dividing the information data is recorded in each of the plurality of blocks in which the storage area is divided. Is a holographic reproduction method for reproducing information data and reproducing information data,
A reference light irradiation process of irradiating the holographic medium with a reference light at a different angle,
Recording angle detection process for detecting angle detection information emitted by the reference light from the holographic medium and controlling the angle of the reference light;
A holographic reproduction method comprising: a data detection step of reproducing information data by inputting reproduction light emitted from the block by reference light, detecting sub-data from the reproduction light, and reproducing information data. It is a holographic recording method in which the wavelength of reference light applied to the holographic medium is changed, and information data is multiplexed and recorded for each predetermined storage area at different wavelengths.
A light modulation process for outputting signal light modulated by information data written to the holographic medium;
A reference light irradiation process for changing the wavelength of the reference light that interferes with the signal light with respect to the holographic medium,
A recording process for recording the sub-data obtained by dividing the information data into a plurality of blocks into which the recording area is divided;
A holographic recording method, comprising: a wavelength detection information writing step of writing wavelength detection information indicating a wavelength corresponding to the block for each block in which the sub data is written. Sub-data that is multiplexed and recorded at different angles by sequentially changing the wavelength of the reference light applied to the holographic medium in which the sub-data obtained by dividing the information data is recorded in each of the plurality of blocks in which the storage area is divided. Is a holographic reproduction method for reproducing information data and reproducing information data,
A reference light irradiation process for irradiating the holographic medium with a reference light at a different wavelength;
Recording angle detection process for detecting wavelength detection information emitted from the holographic medium by the reference light and controlling the wavelength of the reference light;
A holographic reproduction method comprising: a data detection step of reproducing information data by inputting reproduction light emitted from the block by reference light, detecting sub-data from the reproduction light, and reproducing information data. The sub-data that divides the information data page is recorded for each block that divides the recording area, and the angle detection information that indicates the recorded wavelength of each sub-data is before and after the wavelength of the reference light of the block when writing the information data. In contrast, the holographic medium is recorded with a predetermined amount of wavelength deviation.

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