Abstract:
An optical information reproducing device, takes advantage of holography and can precisely detect a well-known pattern disposed at a prescribed location within a page and is used for correcting position deviation, rotation deviation, and magnification deviation. The optical fiber reproducing device includes a detection unit that detects the position information of a marker as a well-known pattern from a page as a 2-dimensional reproduction signal from a hologram, a detection error position estimating unit that estimates presence/absence of detection error in the position information of the marker and estimates the position where the detection error occurs if there is detection error, a position correcting unit that corrects the marker position information of the detection error position specified by the detection error position estimating unit, and a signal detection unit that detects each signal from within the page based on the corrected marker position information.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a device that reproduces information from recording media by using holography. 
       BACKGROUND ART 
       [0002]    At the present time, merchandising of an optical disc having a recording density of approximately 100 GB is possible for public welfare as well owing to Blu-ray Disc™ standard using a blue-violet semiconductor laser. Hereafter, implementation of a large capacity exceeding 500 GB is desired in the optical disc as well. For implementing such an ultrahigh density in the optical disc, however, a high-density technique according to a new system different from the conventional high-density technique using a shorter wavelength and a higher NA of the object lens is necessary. 
         [0003]    In the midst of studies concerning a storage technique of next generation, the hologram recording technique of recording digital information by utilizing the holography attracts attention. As for the hologram recording technique, there is, for example, JP-A-2004-272268 (Patent Literature 1). JP-A-2004-272268 describes the so-called angular multiplexing recording system, in which different page data is displayed on a spatial light modulator while an incidence angle of a reference beam onto optical information recording media is changed and multiplexing recording is conducted. In addition, JP-A-2004-272268 describes a technique of shortening the spacing between adjacent holograms by focusing a signal beam with a lens and disposing an aperture (spatial filter) in its beam waist. 
         [0004]    Furthermore, as for the hologram recording technique, there is, for example, WO2004-102542 (Patent Literature 2). In an example using a shift multiplexing system described in WO2004-102542, a beam from inner pixels is used as a signal beam and a beam from outer strip shaped pixels is used as a reference beam in one spatial light modulator. Both beams are focused onto optical information recording media by using the same lens. The signal beam and the reference beam are caused to interfere with each other in the vicinity of a focal point plane of the lens, and holograms are recorded. 
         [0005]    As for a marker retrieval technique at the time of hologram reproducing, there is, for example, JP-A-2008-139125 (Patent Literature 3). In JP-A-2008439125, there is description “A hologram data area identification device  1  identifies a hologram data area, which is an area occupied by a hologram, from, a hologram image which is input from a photodetector. The hologram data area identification device  1  includes a frame buffer memory  3 , an edge detection means  5 , template comparison means  7 , a template image storage means  9 , and a centroid detection means  11 .” 
       CITATION LIST 
     Patent Literature 
     PATENT LITERATURE 1: JP-A-2004-272268 
     PATENT LITERATURE 2: WO-2004-102542 
     PATENT LITERATURE 3: JP-A-2008-139125 
     SUMMARY OF INVENTION 
     Technical Problem 
       [0006]    By the way, in an optical information reproducing device utilizing holography, a known pattern disposed in a predetermined place in a page is detected when reproducing information, and position deviation, rotation deviation, magnification deviation, and the like are coped with on the basis of position information of the known pattern. However, there is a problem that the signal-to-noise ratio (SNR) becomes low in a case where an error has occurred in detection of the known pattern. This is caused by false detection of the known pattern in a case where user data resembling the known pattern exists near the known pattern. 
         [0007]    In the technique described in Patent Literature 3, there is no disclosure at all concerning the problem or configuration as to whether the value of the known pattern is used after confirming the reliability of the known pattern as described above. 
         [0008]    The present invention has been achieved in view of the above-described problem. It is an object of the present invention to provide an optical information reproducing device and its method capable of detecting a known pattern in a page with high precision in a holographic memory. 
       Solution to Problem 
       [0009]    The above-described problem is solved by, for example, judging the reliability of the marker value itself. 
       Advantageous Effects of Invention 
       [0010]    According to the present invention, it is possible to detect a known patter in a page with high precision in a holographic memory. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1  is a schematic diagram showing an embodiment of a signal position detection circuit in an optical information recording and reproducing device; 
           [0012]      FIG. 2  is a schematic diagram showing an embodiment of an optical information recording and reproducing device; 
           [0013]      FIG. 3  is a schematic diagram showing an embodiment of a pickup in an optical information recording and reproducing device; 
           [0014]      FIG. 4  is a schematic diagram showing an embodiment of a pickup in an optical information recording and reproducing device; 
           [0015]      FIG. 5  is a schematic diagram showing an embodiment of a pickup in an optical information recording and reproducing device; 
           [0016]      FIG. 6  is a schematic diagram showing an embodiment of an operation flow of an optical information recording and reproducing device; 
           [0017]      FIG. 7  is a schematic diagram showing an embodiment of a signal generation circuit in an optical information recording and reproducing device; 
           [0018]      FIG. 8  is a schematic diagram showing an embodiment of a signal processing circuit in an optical information recording and reproducing device; 
           [0019]      FIG. 9  is a schematic diagram showing an embodiment of an operation flow of a signal generation circuit and a signal processing circuit; 
           [0020]      FIG. 10  is a schematic diagram showing an embodiment of a layer structure of optical information recording media having a reflection layer; 
           [0021]      FIG. 11  is a schematic diagram showing an embodiment of a signal processing circuit in an optical information recording and reproducing device; 
           [0022]      FIG. 12  is a schematic diagram showing an embodiment of a page; 
           [0023]      FIG. 13  is a schematic diagram showing examples of a marker position deviation quantity, a detection error estimated value, and a marker position deviation quantity (after corrected) at the time of marker detection; 
           [0024]      FIG. 14  is a schematic diagram showing an embodiment of an operation flow of signal position detection in an optical information recording and reproducing device; 
           [0025]      FIG. 15  is a schematic diagram showing an embodiment of a signal processing circuit in an optical information recording and reproducing device; 
           [0026]      FIG. 16  is a schematic diagram showing an embodiment of an operation flow of signal position detection in an optical information recording and reproducing device; and 
           [0027]      FIG. 17  is a schematic diagram showing an embodiment of an operation flow of signal position detection in an optical information recording and reproducing device. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0028]    Hereafter, embodiments of the present invention will be described with reference to the drawings. 
       Embodiment 1 
       [0029]    A first embodiment of the present invention will now be described with reference to  FIGS. 1 to 14 . 
         [0030]      FIG. 2  is a block diagram showing a recording and reproducing device of optical information recording media for recording and/or reproducing digital information by utilizing holography. 
         [0031]    An optical information recording and reproducing device  10  is connected to an external control device  91  via an input/output control circuit  90 . At the time of recording, the optical information recording and reproducing device  10  receives an information signal to be recorded, from the external control device  91  by using the input/output control circuit  90 . At the time of reproducing, the optical information recording and reproducing device  10  transmits a reproduced information signal to the external control device  91  by using the input/output control circuit  90 . 
         [0032]    The optical information recording and reproducing device  10  includes a pickup  11 , a reproducing reference beam optical system  12 , a cure optical system  13 , a disc rotation angle detecting optical system  14  and a rotary motor  50 . Optical information recording media  1  is configured to be capable of being rotated by the rotary motor  50 . 
         [0033]    The pickup  11  plays a role of emitting a reference beam and a signal beam onto the optical information recoding media  1  and recording digital information on the recording media by utilizing holography. At this time, an information signal to be recorded is sent into a spatial light modulator in the pickup  11  via a signal generation circuit  86  by a controller  89 , and the signal beam is modulated by the spatial light modulator. 
         [0034]    When reproducing information recorded on the optical information recording media  1 , the reproducing reference beam optical system  12  generates a light wave to cause the reference beam emitted from the pickup  11  to be incident on the optical information recording media in a sense opposite to that at the time of recording. A photodetector, which will be described later, in the pickup  11  detects a reproduced beam reproduced by using the reproducing reference beam. A signal processing circuit  85  reproduces a signal. 
         [0035]    The controller  89  controls open/close time of a shutter in the pickup  11  via a shutter control circuit  87 . As a result, irradiation time of the reference beam and the signal beam with which the optical information recording media  1  is irradiated can be adjusted. 
         [0036]    The cure optical system  13  plays a role of generating a light beam used in precure and postcure of the optical information recording media  1 . The precure is a pre-process of irradiating a desired position in the optical information recording media  1  with a predetermined light beam before irradiating the desired position with the reference beam and the signal beam when recording information in the desired position. The postcure is a post-process of irradiating a desired position in the optical information recording media  1  with a predetermined light beam to make rewriting impossible after information is recorded in the desired position. 
         [0037]    The disc rotation angle detecting optical system  14  is used to detect a rotation angle of the optical information recording media  1 . When adjusting the optical information recording media  1  to a predetermined rotation angle, the disc rotation angle detecting optical system  14  detects a signal depending upon the rotation angle and the controller  89  can control the rotation angle of the optical information recording media  1  via a disc rotary motor control circuit  88  by using the detected signal. 
         [0038]    A light source drive circuit  82  supplies a predetermined light source drive current to light sources in the pickup  11 , the cure optical system  13 , and the disc rotation angle detecting optical system  14 . Light sources can emit light beams with predetermined light quantities, respectively. 
         [0039]    Furthermore, as for each of the pickup  11  and the disc cure optical system  13 , a mechanism capable of sliding a position in a radial direction of the optical information recording media  1  is provided. Position control is exercised via an access control circuit  81 . 
         [0040]    By the way, the recording technique utilizing the principle of the angular multiplexing of holography has tendency that an allowable error for angle deviation of the reference beam becomes extremely small. 
         [0041]    Therefore, it becomes necessary that a mechanism for detecting a deviation quantity of the reference beam angle is provided in the pickup  11 , a servo signal generation circuit  83  generates a signal for servo control, and a servo mechanism for correcting the deviation quantity via a servo control circuit  84  is provided in the optical information recording and reproducing device  10 . 
         [0042]    Furthermore, as for the pickup  11 , the cure optical system  13 , and the disc rotation angle detecting optical system  14 , several optical system configurations or all optical system configurations may be collected to one configuration and simplified. 
         [0043]      FIG. 3  shows a recording principle in an example of a basic optical system configuration of the pickup  11  in the optical information recording and reproducing device  10 . A light beam emitted from a light source  301  passes through a collimate lens  302  and incident on a shutter  303 . When the shutter  303  is open, the light beam passes through the shutter  303 . Then, the light beam is controlled in polarization direction to have a light quantity ratio between p-polarized light and s-polarized light set to a desired ratio by an optical element  304  including, for example, a half-wave plate. Then, the light beam is incident on a PBS (Polarization Beam Splitter) prism  305 . 
         [0044]    The light beam which has passed through the PBS prism  305  functions as a signal beam  306 . After being expanded in light beam diameter by a beam expander  308 , the signal beam passes through a phase mask  309 , a relay lens  310  and a PBS prism  311  and is incident on a spatial light modulator  312 . 
         [0045]    The signal beam added with information by the spatial light modulator  312  is reflected by the PBS prism  311 , and propagates through a relay lens  313  and a spatial filter  314 . Then, the signal beam is focused onto the optical information recording media  1  by an object lens  315 . 
         [0046]    On the other hand, the light beam reflected by the PBS prism  305  functions as a reference beam  307 . The reference beam  307  is set to a predetermined polarization direction depending upon whether to conduct recording or reproducing by a polarization direction conversion element  316 . Then, the reference beam  307  is incident on a galvanometer mirror  319  via a mirror  317  and a mirror  318 . Since the galvanometer mirror  319  can be adjusted in angle by an actuator  320 , an incidence angle of the reference beam incident on the optical information recording media  1  after passing through a lens  321  and a lens  322  can be set to a desired angle. By the way, in order to set the incidence angle of the reference beam, an element that converts a wave surface may be used instead of the galvanometer mirror. 
         [0047]    In this way, the signal beam and the reference beam are incident on the optical information recording media  1  to overlap each other. As a result, an interference fringe pattern is formed in the recording media. Information is recorded by writing this pattern into the recording media. Furthermore, since the incidence angle of the reference beam incident on the optical information recording media  1  can be changed by the galvanometer mirror  319 , recording using angular multiplexing is possible. 
         [0048]    Hereafter, in holograms recorded in the same area with the reference beam angle changed, a hologram corresponding to each reference beam angle is referred to as page, and a set of pages angular-multiplexed in the same area is referred to as book. 
         [0049]      FIG. 4  shows a principle of reproducing in an example of a basic optical system configuration of the pickup  11  in the optical information recording and reproducing device  10 . When reproducing recorded information, the reference beam is incident on the optical information recording media  1  as described above and a light beam that has passed through the optical information recording media  1  is reflected by a galvanometer mirror  324  which can be adjusted in angle by an actuator  323 . As a result, a reference beam for reproducing is generated. 
         [0050]    A reproduced beam reproduced by using the reproducing reference beam propagates through the object lens  315 , the relay lens  313  and the spatial filter  314 . Then, the reproduced beam passes through the PBS prism  311  and is incident on a photodetector  325 , and the recorded signal can be reproduced. As the photodetector  325 , an imaging element such as, for example, a CMOS image sensor or a CCD image sensor, can be used. However, any element may be used as long as the element can reproduce page data. 
         [0051]      FIG. 5  is a diagram showing a different configuration of the pickup  11 . In  FIG. 5 , a light beam emitted from a light source  501  passes through a collimate lens  502 , and is incident on a shutter  503 . When the shutter  503  is open, the light beam passes through the shutter  503 . Then, the light beam is controlled in polarization direction to have a light quantity ratio between p-polarized light and s-polarized light set to a desired ratio by an optical element  504  including, for example, a half-wave plate. Then, the light beam is incident on a PBS prism  505 . 
         [0052]    The light beam which has passed through the PBS prism  505  is incident on a spatial light modulator  508  via a PBS prism  507 . A signal beam  506  added with information by the spatial light modulator  508  is reflected by the PBS prism  507 , and propagates through an angle filter  509  which passes through only a light beam of a predetermined incidence angle. Then, the signal beam is focused onto the hologram recording media  1  by an object lens  510 . 
         [0053]    On the other hand, the light beam reflected by the PBS prism  505  functions as a reference beam  512 . The reference beam  512  is set to a predetermined polarization direction depending upon whether to conduct recording or reproducing by a polarization direction conversion element  519 . Then, the reference beam  512  is incident on a lens  515  via a mirror  513  and a mirror  514 . The lens  515  plays a role of focusing the reference beam  512  on a back focus plane of the object lens  510 . The reference beam focused on the back focus plane of the object lens  510  once is converted to a parallel beam again by the object lens  510  and incident on the hologram recording media  1 . 
         [0054]    Here, the object lens  510  or an optical block  521  can be driven, for example, in a direction indicated by reference numeral  520 . A relative position relation between the object lens  510  and a focal point on the back focus plane of the object lens  510  is changed by shifting the position of the object lens  510  or the optical block  521  along the drive direction  520 . As a result, an incidence angle of the reference beam incident on the hologram recording media  1  can be set to a desired angle. By the way, the incidence angle of the reference beam may be set to a desired angle by driving the mirror  514  with an actuator instead of driving the object lens  510  or the optical block  521 . 
         [0055]    In this way, the signal beam and the reference beam are incident on the hologram recording media  1  while overlapping each other. As a result, an interference fringe pattern is formed in the recording media. Information is recorded by writing this pattern into the recording media. Furthermore, since the incidence angle of the reference beam incident on the hologram recording media  1  can be changed by shifting the position of the object lens  510  or the optical block  521  along the drive direction  520 , recording using angular multiplexing is possible. 
         [0056]    When reproducing recorded information, a reference beam for reproducing is generated by causing the reference beam to be incident on the hologram recording media  1  as described above and reflecting a light beam that has passed through the hologram recording media  1  with a galvanometer mirror  516 . A reproduced beam reproduced by using the reproducing reference beam propagates through the object lens  510  and the angle filter  509 . Then, the reproduced beam passes through the PBS prism  507  and is incident on a photodetector  518 , and the recorded signal can be reproduced. 
         [0057]    The optical system shown in  FIG. 5  has a configuration in which the signal beam and the reference beam are incident on the same object lens. As a result, the optical system shown in  FIG. 5  has an advantage that it can be reduced in size remarkably as compared with the configuration of the optical system. 
         [0058]      FIG. 6  shows an operation flow of recording and reproducing in the optical information recording and reproducing device  10 . In particular, a flow concerning recording and reproducing utilizing holography will now be described. 
         [0059]      FIG. 6(   a ) shows a flow of operation conducted until preparations for, recording or reproducing are completed since the optical information recording media  1  is inserted into the optical information recording and reproducing device  10 .  FIG. 6(   b ) shows a flow of operation conducted until information is recorded on the optical information recording media  1  since a state in which the preparations are completed.  FIG. 6(   c ) shows a flow of operation conducted until information recorded on the optical information recording media  1  is reproduced since the state in which the preparations are completed. 
         [0060]    As shown in  FIG. 6(   a ), media is inserted ( 601 ). The optical information recording and reproducing device  10  conducts disc discrimination to determine whether, for example, the inserted media is media on which recording or reproducing of digital information is conducted utilizing holography ( 602 ). 
         [0061]    If it is determined as a result of the disc discrimination that the inserted media is media on which recording or reproducing of digital information is conducted utilizing holography, the optical information recording and reproducing device  10  reads out control data provided on the optical information recording media ( 603 ), and acquires, for example, information concerning the optical information recording media and, for example, information concerning various setting conditions at the time of recording or reproducing. 
         [0062]    After reading the control data, the optical information recording and reproducing device  100  conducts various adjustments according to the control data and learning processing concerning the pickup  11  ( 604 ), and completes preparations for recording or reproducing ( 605 ). 
         [0063]    The flow of operation conducted until information is recorded since the preparation completion state is shown in  FIG. 6(   b ). First, the optical information recording and reproducing device  100  receives data to be recorded ( 611 ), and sends information depending upon the data into the spatial light modulator in the pickup  11 . 
         [0064]    Then, the optical information recording and reproducing device  100  previously conducts various kinds of learning processing for recording such as, for example, power optimization of the light source  301  and optimization of exposure time using the shutter, as occasion demands in order to make it possible to record high quality information on the optical information recording media ( 612 ). 
         [0065]    Then, in seek operation ( 613 ), the optical information recording and reproducing device  10  controls the access control circuit  81  to position the pickup  11  and the cure optical system  13  in predetermined positions on the optical information recording media. In a case where the optical information recording media  1  has address information, the optical information recording and reproducing device  10  reproduces address information and ascertains whether the pickup  11  and the cure optical system  13  are positioned in target positions. Unless the pickup  11  and the cure optical system  13  are positioned in target positions, the optical information recording and reproducing device  10  calculates a deviation from a predetermined position and repeats the operation of positioning again. 
         [0066]    Then, the optical information recording and reproducing device  10  precures a predetermined area by using the light beam emitted from the cure optical system  13  ( 614 ), and records data by using the reference beam and the signal beam emitted from the pickup  11  ( 615 ). 
         [0067]    After recording data, the optical information recording and reproducing device  10  conducts postcure by using the light beam emitted from the cure optical system  13  ( 616 ). The optical information recording and reproducing device  10  may verify data as occasion demands. 
         [0068]    The flow of operation conducted until information is reproduced since the preparation completion state is shown in  FIG. 6(   c ). First, in seek operation ( 621 ), the optical information recording and reproducing device  10  controls the access control circuit  81  to position the pickup  11  and the cure optical system  13  in predetermined positions on the optical information recording media. In a case where the optical information recording media  1  has address information, the optical information recording and reproducing device  10  reproduces address information and ascertains whether the pickup  11  and the cure optical system  13  are positioned in target positions. Unless the pickup  11  and the cure optical system  13  are positioned in target positions, the optical information recording and reproducing device  10  calculates a deviation from a predetermined position and repeats the operation of positioning again. 
         [0069]    Then, the optical information recording and reproducing device  10  emits the reference beam from the pickup  11 , reads out information recorded on the optical information recording media ( 622 ), and transmits reproduced data ( 613 ). 
         [0070]      FIG. 9  shows a data processing flow at the time of recording and reproducing.  FIG. 9(   a ) shows a flow of recording data processing in the signal generation circuit  86  conducted after receiving  611  of recording data in the input/output control circuit  90  until the recording data is converted to two-dimensional data on the spatial light modulator  312 .  FIG. 9(   b ) shows a flow of reproduced data processing in the signal processing circuit  85  after detection of two-dimensional data in the photodetector  325  until reproduced data transmission  624  in the input/output control circuit  90 . 
         [0071]    Data processing at the time of recording will now be described with reference to  FIG. 9(   a ). Upon receiving user data ( 901 ), the user data is divided into a plurality of data strings and each data string is converted to CRC to make it possible to conduct error detection at the time of reproducing ( 902 ). With the object of making the number of on pixels nearly equal to the number of off pixels and preventing the same pattern from being repeated, scrambling of adding a pseudo random number data string to each data string is conducted ( 903 ). Then, error correction coding using the Reed-Solomon code or the like is conducted to make it possible to conduct error correction at the time of reproducing ( 904 ). Then, the data string is converted to M*N two-dimensional data and the conversion is repeated for one page data. Thereby, two-dimensional data corresponding to one page is constituted ( 905 ). Markers which become reference in image position detection and image distortion correction at the time of reproducing are added to the two-dimensional data constituted in this way ( 906 ). Resultant data is transferred to the spatial light modulator  312  ( 907 ). 
         [0072]    The data processing flow at the time of reproducing will now be described with reference to  FIG. 9(   b ). Image data detected by the photodetector  325  is transferred to the signal processing circuit  85  ( 911 ). An image position is detected by using markers included in the image data as reference ( 912 ). Distortions such as an inclination, a magnification and distortion of the image are corrected ( 913 ). Then, binarization processing is conducted ( 914 ). Markers are removed ( 915 ), and thereby two-dimensional data corresponding to one page is acquired ( 916 ). The two-dimensional data obtained in this way is converted to a plurality of data stings, and then error correction processing is conducted ( 917 ). And a parity data string is removed. Then, descrambling processing is conducted ( 918 ). Error detection processing using the CRC is conducted ( 919 ). After CRC parities are removed, user data is transmitted via the input/output control circuit  90  ( 920 ). 
         [0073]      FIG. 7  is a block diagram of the signal generation circuit  86  in the optical information recording and reproducing device  10 . 
         [0074]    When input of user data to the output control circuit  90  is started, the input/output control circuit  90  gives a notice that input of user data is started to the controller  89 . Upon receiving the notice, the controller  89  instructs the signal generation circuit  86  to conduct recording processing of data corresponding to one page which is input from the input/output control circuit  90 . The processing instruction from the controller  89  is given to a sub-controller  701  in the signal generation circuit  86  via a control line  708 . Upon receiving the instruction, the sub-controller  701  controls respective signal processing circuits via the control line  708  to cause the respective signal processing circuits to operate in parallel. First, the sub-controller  701  controls a memory control circuit  703  to store user data which is input from the input/output control circuit  90  via a data line  709  into a memory  702 . If user data stored in the memory  702  amounts to a certain determinate quantity, a CRC operation circuit  704  exercises control to convert user data to CRC. Then, a scramble circuit  705  conducts scrambling to add a pseudo random number data string to data converted to CRC. An error correction coding circuit  706  exercises control to conduct error correction coding of adding a parity data string. Finally, a pickup interface circuit  707  reads out data subjected to error correction coding from the memory  702  in an arrangement order of two-dimensional data on the spatial light modulator  312 , adds markers, which become reference at the time of reproducing, to the two-dimensional data, and then transfers resultant two-dimensional data to the spatial light modulator  312  in the pickup  11 . 
         [0075]      FIG. 8  is a block diagram of the signal processing circuit  85  in the optical information recording and reproducing device  10 . 
         [0076]    If the photodetector  325  in the pickup  11  detects image data, the controller  89  instructs the signal processing circuit  85  to conduct reproducing processing on data corresponding to one page which is input from the pickup  11 . The processing instruction from the controller  89  is given to a sub-controller  801  in the signal processing circuit  85  via a control line  811 . Upon receiving the instruction, the sub-controller  801  controls respective signal processing circuits via the control line  811  to operate the signal processing circuits in parallel. First, the sub controller  801  controls a memory control circuit  803  to store image data, which is input from the pickup  11  via a pickup interface circuit  810  and a data line  812 , into a memory  802 . If data stored in the memory  802  amounts to a certain determinate quantity, the image position detection circuit  809  exercises control of detecting markers from image data stored in the memory  802  and extracting an effective data range. Then, an image distortion correction circuit  808  exercises control of conducting correction of distortions such as an inclination, a magnification and distortion of the image by using the detected markers and converting the image data to an expected size of two-dimensional data. A binarization circuit  807  exercises control of conducting binarization by determining whether each bit data in a plurality of bits included in two-dimensional data subjected to the size conversion is “0” or “1” and storing resultant data onto the memory  802  in an arrangement of output of reproduced data. Then, an error correction circuit  806  corrects an error included in each data string. A descrambling circuit  805  cancels scrambling which adds a pseudo random number data string. Then, a CRC operation circuit  804  confirms that an error is not contained in user data on the memory  802 . Then, user data is transferred from the memory  802  to the input/output control circuit  90 . 
         [0077]      FIG. 10  is a diagram showing a layer structure of optical information recording media having a reflection layer. In  FIG. 10 , (1) indicates a state in which information is being recorded in the optical information recording media, and (2) indicates a state in which information is being reproduced from the optical information recording media. 
         [0078]    The optical information recording media  1  includes a transparent cover layer  1000 , a recording layer  1002 , an optical absorption/optical transmission layer  1006 , an optical reflection layer  1010 , and a third transparent protection layer  1012  in order from the optical pickup  11  side. An interference pattern between a reference beam  10 A and a signal beam  10 B is recorded in the recording layer  1002 . 
         [0079]    The optical absorption/optical transmission layer  1006  changes in physical properties to absorb the reference beam  10 A and the signal beam  10 B at the time of information recording and transmit the reference beam at the time of information reproducing. For example, the coloring/decolorizing state of the optical absorption/optical transmission layer  1006  is changed by applying a voltage to the optical recording media  1 . In other words, at the time of information recording, the optical absorption/optical transmission layer  1006  assumes the coloring state and absorbs the reference beam  10 A and the signal beam  10 B which have passed through the recording layer  1002 . At the time of information reproducing, the optical absorption/optical transmission layer  1006  assumes the decolorizing state and transmits the reference beam (T. Ando et, al.: Technical Digest ISOM (2006), Th-PP-10). The reference beam  10 A which has passed through the optical absorption/optical transmission layer  1006  is reflected by the optical reflection layer  1010  and becomes a reference beam for reproducing 10C. 
         [0080]    Furthermore, WO3 functioning as an electrochromic (EC) material described in A. Hirotsune et. al.: Technical Digest ISOM (2006), Mo-B-04 can be used in the optical absorption/optical transmission layer  1006 . 
         [0081]    Coloring and decolorizing are caused reversibly by applying a voltage to this material. At the time of information recording, coloring is caused and the beam is absorbed. At the time of information reproducing, decolorizing is caused and the beam is transmitted. 
         [0082]    Owing to the configuration shown in  FIG. 10 , the reference beam optical system for reproducing becomes unnecessary and size shrinking of the drive becomes possible. 
         [0083]    Here, the present inventor will describe a technique for detecting a known pattern in a page in a holographic memory with high precision. 
         [0084]      FIG. 12  is a schematic diagram showing an embodiment of a page. In a page  421 , sync marks  422  are disposed at four corners. The sync marks  422  are utilized for correction of position deviation, rotation and magnification deviation of the page. After the pickup has detected the page, position detection of the sync marks  422  is first conducted. In a data portion  424  in the page  421 , markers  423  are disposed. The markers  423  are provided to cope with position deviation that cannot be removed with the correction utilizing the sync marks  422 . Position deviation of the data portion is calculated on the basis of position information of the markers  423 , and the data portion is detected. In some cases, a pitch of pixels smaller than that of the spatial light modulator is used as the pitch of pixels of a camera in the pickup. When detecting the data portion in this case, oversampling canceling processing of restoring the pitch of pixels in the camera to the pixel size of the spatial light modulator on the basis of information of position deviation of the data portion is conducted. 
         [0085]      FIG. 11  is a schematic diagram showing an embodiment of the signal processing circuit in the optical information recording and reproducing device. The pickup  11  outputs a detected reproduced page to a page distortion adjustment circuit  401 . The page distortion adjustment circuit  401  detects sync marks in an input reproduced page, calculates a position deviation quantity, a rotation quantity and a magnification deviation quantity on the basis of position information of the sync marks, and outputs page data corrected in these deviations to a signal position detection circuit  402 . For the correction of the deviation quantity, the affine transformation utilized in, for example, the image processing field is utilized. The signal position detection circuit  402  receives corrected page data, detects position information of each signal by using a method which will be described later, and outputs page data and position information of each signal to an oversampling canceling circuit  403 . The oversampling canceling circuit  403  receives the page data and position information of each signal, cancels the oversampling of the page data to make the number of pixels in page data equal to the number of pixels in the spatial light modulator, and outputs the page data subjected to the oversampling canceling to an equalization circuit  404 . As for a method of oversampling, for example, a method of using filter coefficients for oversampling canceling at each position deviation quantity previously calculated and conducting FIR filter processing is used. The equalization circuit  404  receives the page data subjected to the oversampling canceling, removes inter-pixel interference by conducting FIR filter processing, and outputs page data subjected to filter processing to a binarization circuit  405 . The binarization circuit  405  receives page data subjected to the filter processing, binarizes the page data by using, for example, a threshold, the maximum likelihood decoding, or Viterbi decoding, and outputs binarized information to the controller  89 . 
         [0086]      FIG. 1  is a schematic diagram showing an embodiment of the signal position detection circuit in the optical information recording and reproducing device. A marker detection circuit  411  receives page data, detects a position of each marker in the page, and outputs the page data and marker position information to a detection error position presumption circuit  412 . In marker position detection, for example, a cross-correlation coefficient between the known marker pattern and a page data signal is calculated, and a position where the cross-correlation coefficient is maximized is identified as marker position. The detection error position presumption circuit  412  receives the page data and the marker position information, presumes a detection error position of the marker position, and outputs the detection error position of the marker position and the page data to a marker position amendment circuit  413 . As for presumption of the detection error position of the marker position, for example, a difference between a deviation quantity of a marker position and an average value of deviation quantities of marker positions in the vicinity is calculated. In a case where the difference value is at least a predetermined value, it is judged that a detection error has occurred. Thereby, a detection error position of the marker position is identified. The marker position amendment circuit  413  receives the detection error position of the marker position and the page data, amends the marker position of the detection error position by, for example, linear interpolation from adjacent marker positions, and outputs the amended marker position information and the page data to a signal position calculation circuit  414 . The signal position calculation circuit  414  receives the amended marker position information and the page data, calculates a position of a signal group in the vicinity of each marker by, for example, conducting linear interpolation from marker positions in the vicinity, and outputs each signal position and the page data. 
         [0087]      FIG. 13  is a schematic diagram showing examples of (a) a marker position deviation quantity at the tune of marker detection, (b) a presumed detection error value, and (c) a marker position deviation quantity (after correction). As shown in  FIG. 13(   a ), a marker position deviation dx for each marker is calculated. A presumed detection error value Er shown in  FIG. 13(   b ) can be calculated by, for example, calculating a difference from an average value of position deviation quantities of markers in the vicinity as represented by the following Equation (1). 
         [0000]        Er=|dx −average value of  dx|   Equation (1)
 
         [0088]    For example, it is presumed that a detection error occurs in a marker that indicates a presumed detection error value Er exceeding a predetermined threshold. As shown in  FIG. 13(   c ), the marker position deviation quantity is amended by conducting linear interpolation according to Equation (2) from position deviation quantities of adjacent markers. Here, dx n  indicates a position deviation quantity of an n-th marker. Equation (2) represents an example of a case where a detection error occurs in the nth marker. By the way, in a case where detection errors occur consecutively, for example, calculation is conducted by linear interpolation from markers in the vicinity in which detection error does not occur. 
         [0000]        dx   n   =dx   n−1   +dx   n+1 )/2 
         [0089]      FIG. 14  is a schematic diagram showing an embodiment of an operation flow of signal position detection in the optical information recording and reproducing device. At the time of signal position detection, marker positions are first detected by utilizing cross-correlation coefficients or the like at  431 . Then, a marker detection error position is presumed at  432 . A position of a marker in the detection error position is corrected on the basis of positions of adjacent markers at  433 . Finally, the position of each signal is calculated by utilizing information of the marker positions at  434 . By the way, although not illustrated, for example, it is also possible to cancel the oversampling on the basis of the amended marker position information and determine whether amendment of the marker position information was proper on the basis of an SNR value. Furthermore, for example, in a case where the SNR is low, processing, such as conducting interpolation by utilizing information of different markers, may be continued. 
         [0090]    By the way, as for the threshold used for judgment of the marker detection error, a value that the device previously has may be used or first, learning of the threshold may be conducted by using the SNR or the like as an index. Furthermore, as for the technique for judging the reliability of a marker, another configuration using the SNR of the marker is also conceivable. In the present embodiment, the point that the reliability of the marker itself is judged is especially distinctive. It is a matter of course that there is a judging technique other than the present embodiment. 
         [0091]    In the method in the present embodiment, amendment of the marker position can be implemented by using only information in the same page. Therefore, there is an advantage that the device configuration can be simplified. 
         [0092]    In the ensuing description, description of contents common to the present embodiment will be omitted. 
       Embodiment 2 
       [0093]    A second embodiment in the present invention will now be described with reference to  FIGS. 15 and 16 . 
         [0094]      FIG. 15  is a schematic diagram showing an embodiment of the signal processing circuit in the optical information recording and reproducing device. A difference from the circuit shown in  FIG. 11  in the embodiment 1 is that a buffer memory  406  is added. The signal position detection circuit  402  receives page data. At time of a page other than the start page, the signal position detection circuit  402  receives marker position deviation information of a previous page as well. The signal position detection circuit  402  detects position information of each signal by using a method which will be described later. The signal position detection circuit  402  outputs corrected page data and the position information of each signal to an oversampling cancel circuit  403 , and outputs marker position deviation information to a buffer memory  406 . The buffer memory  406  receives the marker position deviation information, and stores the marker position deviation information until time of processing of the next page. At time of signal position detection of the next page, the buffer memory  406  outputs the marker position deviation information to the signal position detection circuit  402 . Operation of other circuits is common to that in the embodiment 1, and consequently description thereof will be omitted. 
         [0095]      FIG. 16  is a schematic diagram showing an embodiment of an operation flow of signal position detection in the optical information recording and reproducing device. At time of signal position detection, first, marker positions are detected by utilizing cross-correlation coefficients or the like at  441 . Then, a marker detection error position is presumed at  442 . It is determined at  443  whether a page subjected to the marker detection is the start page. Unless the page subjected to the marker detection is the start page at  443 , the position of a marker in the detection error position is corrected on the basis of the same marker position in the previous page at  444 . As for the correction of the marker position, the marker position deviation is calculated by, for example, regarding the marker position deviation as the same quantity as the position deviation quantity of the same marker position in the previous page, and the marker position is corrected. Finally, at  445 , the position of each signal is calculated by utilizing the information of the marker positions. If the page subjected to the marker detection is the start page in determination at  443 , the position of the marker in the detection error position is corrected on the basis of adjacent marker positions according to a method similar to that in embodiment 1, at  446 . 
         [0096]    By the way, although not illustrated, it is also possible to cancel the oversampling on the basis of, for example, amended marker position information and determine whether amendment of the marker position information was proper, on the basis of the SNR value. Furthermore, for example, in a case where the SNR is low, processing, such as conducting interpolation by utilizing information of a different marker, may be continued. 
         [0097]    By the way, as for the presumption of the detection error position, the presumption may be conducted by conducting comparison with information of markers in the vicinity in the same page as described above, the presumption may be conducted by conducting comparison with information of markers in pages in the vicinity in the same book, or the presumption may be conducted by conducting comparison with information of markers in the same page or pages in the vicinity in another book. 
         [0098]    Furthermore, as for the amendment of the detection error position, the marker position may be calculated supposing that deviation of the same quantity as a position deviation quantity of a marker in an adjacent page has occurred as described earlier, the marker position may be calculated by conducting linear interpolation or nonlinear interpolation on marker position information or a position deviation quantity on a page in the vicinity, the marker position may be calculated by conducting linear interpolation or nonlinear interpolation in the same way on marker position information or a position deviation quantity in a page in another book, or the marker position may be calculated supposing that a deviation of the same quantity has occurred. 
         [0099]    In the method in the present embodiment, the marker position is amended by using information in another page. Therefore, there is an advantage that the precision is higher as compared with the method in the embodiment 1 in some cases. 
         [0100]    In the ensuing description, description of contents common to the present embodiment will be omitted. 
       Embodiment 3 
       [0101]    A third embodiment in the present invention will now be described with reference to  FIG. 17 . By the way, an embodiment of the device can be implemented by using a configuration similar to that in embodiment 2. 
         [0102]      FIG. 17  is a schematic diagram showing an embodiment of an operation flow of signal position detection in the optical information recording and reproducing device. At the time of signal position detection, positions of markers are first detected by utilizing cross-correlation coefficients or the like at  451 . Then, a marker detection error position is presumed at  452 . At  453 , the marker position in the detection error position is compared with a marker position in an adjacent page, and it is determined whether a detection error has actually occurred. As for the determination as to whether a detection error has actually occurred, for example, a difference between a position deviation quantity of the market position presumed to be a detection error at  452  and a position deviation quantity of a marker in the same position in an adjacent page is found. A portion where the difference value exceeds a predetermined threshold is judged that a detection error has occurred there. If the difference value is the predetermined threshold or less, it is judged that there is no detection error. In a case where a page which is being reproduced is a start page in a book, the next page may be reproduced, or it may be determined whether a detection error has occurred by conducting comparison with a marker position in the same page in another book. Only for a portion having no correlation with an adjacent page, the marker position is corrected according to methods described in embodiment 1 or 2, at  454 . Finally, the position of each signal is calculated by utilizing information of the marker positions at  455 . 
         [0103]    By the way, as for the presumption of the detection error position, the presumption may be conducted by conducting comparison with information of markers in the vicinity in the same page as described above, the presumption may be conducted by conducting comparison with information of markers in pages in the vicinity in the same book, or the presumption may be conducted by conducting comparison with information of markers in the same page or pages in the vicinity in another book. 
         [0104]    By the way, although not illustrated, it is also possible to cancel the oversampling on the basis of, for example, amended marker position information and determine whether amendment of the marker position information was proper, on the basis of the SNR value. Furthermore, for example, in a case where the SNR is low, processing, such as conducting interpolation by utilizing information of a different marker, may be continued. 
         [0105]    Furthermore, as for the amendment of the detection error position, the marker position may be calculated supposing that deviation of the same quantity as a position deviation quantity of a marker in an adjacent page has occurred as described earlier, the marker position may be calculated by conducting linear interpolation or nonlinear interpolation on marker position information or a position deviation quantity on a page in the vicinity, the marker position may be calculated by conducting linear interpolation or nonlinear interpolation in the same way on marker position information or a position deviation quantity in a page in another book, or the marker position may be calculated supposing that a deviation of the same quantity has occurred. 
         [0106]    As for the determination as to whether a detection error has actually occurred, it may be determined on the basis of a difference value from a position deviation quantity of a marker in the same position in an adjacent page in the same book as described earlier, or it may be determined on the basis of a difference value from a marker position deviation quantity in the same page in another book or in an adjacent page. 
         [0107]    In the method in the present embodiment, it is determined whether a detection error has actually occurred, before amending the marker position. Therefore, detection with higher decision can be conducted in some cases. 
         [0108]    By the way, the present embodiment can also be described as follows: an optical information reproducing device which reproduces information from optical information recording media having information recorded by utilizing holography, sync marks recorded for coarse adjustment, and markers recorded for fine adjustment, the optical information reproducing device including a detection unit for detecting position information of the sync marks and the markers from page data, which is a two-dimensional reproduced signal obtained from the optical information recording media, and a control unit for determining whether position information of a marker is reliable on the basis of position information of the marker detected by the detection unit, upon determining that there is a detection error, the control unit amending position information of the marker having the detection error on the basis of another marker. 
         [0109]    The present invention is not restricted to the above-described embodiments, but various modifications are included. For example, the embodiments have been described in detail in order to describe the present invention intelligibly, and each of the embodiments is not necessarily restricted to the configuration having all described components. Furthermore, it is possible to replace a part of a configuration in an embodiment by a part of a configuration in another embodiment, and it is possible to add a part of a configuration in an embodiment to a configuration in another embodiment. Furthermore, as for a part of a configuration in each embodiment, it is possible to conduct addition, deletion, and replacement of a part of a configuration in another embodiment. 
         [0110]    Furthermore, as for each of the above-described configurations, functions, processing units, and processing means, a part or the whole thereof may be implemented by hardware by, for example, designing using integrated circuits. Each of the above-described configurations, functions, and the like may be implemented by software by using a processor which interprets and executes a program implementing each function. Information such as a program, a table, and a file implementing each function can be stored in a storage device such as a memory, a hard disc, or an SSD (Solid State Drive) or recording media such as an IC card, an SD card, or a DVD. 
         [0111]    Furthermore, as for control lines and information lines, those considered to be necessary for description are shown. All control lines and information lines on products are not necessarily shown. As a matter of fact, it may be considered that almost all components are connected to each other. 
       REFERENCE SIGNS LIST 
       [0000]    
       
         
           
               1 : Optical information recording media 
               10 : Optical information recording and reproducing device 
               11 : Pickup 
               12 : Reproducing reference beam optical system 
               13 : Disc cure optical system 
               14 : Disc rotation angle detecting optical system 
               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 rotary motor control circuit 
               89 : Controller 
               90 : Input/output control circuit 
               91 : External control device 
               301 : Light source 
               303 : Shutter 
               306 : Signal beam 
               307 : Reference beam 
               308 : Beam expander 
               309 : Phase mask 
               310 : Relay lens 
               311 : PBS prism 
               312 : Spatial light modulator 
               313 : Relay lens 
               314 : Spatial filter 
               315 : Object lens 
               316 : Polarization direction conversion element 
               320 : Actuator 
               321 : Lens 
               322 : Lens 
               323 : Actuator 
               324 : Mirror 
               325 : Photodetector 
               401 : Page distortion adjustment circuit 
               402 : Signal position detection circuit 
               403 : Oversampling canceling circuit 
               404 : Equalization circuit 
               405 : Binarization circuit 
               406 : Buffer memory 
               411 : Marker detection circuit 
               412 : Detection error position presumption circuit 
               413 : Marker position amendment circuit 
               414 : Signal position calculation circuit 
               421 : Page 
               422 : Sync mark 
               423 : Marker 
               424 : Data portion 
               501 : Light source 
               502 : Collimate lens 
               503 : Shutter 
               504 : Optical element 
               505 : PBS prism 
               506 : Signal beam 
               507 : PBS prism 
               508 : Spatial light modulator 
               509 : Angle filter 
               510 : Object lens 
               511 : Object lens actuator 
               512 : Reference beam 
               513 : Mirror 
               514 : Mirror 
               515 : Lens 
               516 : Galvanometer mirror 
               517 : Actuator 
               518 : Photodetector 
               519 : Polarization direction conversion element 
               520 : Drive direction 
               521 : Optical block