JP5953284B2 - Optical information recording medium, optical information recording apparatus, optical information recording method, optical information reproducing apparatus, and optical information reproducing method. - Google Patents

Description

  The present invention relates to an apparatus for recording information on and / or reproducing information from an optical information recording medium using holography.

  At present, commercialization of an optical disc having a recording density of about 50 GB is possible even for consumer use according to the Blu-ray Disc (BD) (Blu-ray is a registered trademark) standard using a blue-violet semiconductor laser. .

  In the future, even optical disks will be put to practical use with a capacity of 100 GB to 1 TB, which is about the same as an HDD (Hard Disc Drive) capacity.

  However, in order to realize such an ultra-high density with an optical disk, a new storage technology different from the trend of the conventional high-density technology due to the shorter wavelength and the higher objective lens NA is required. .

  While research on next-generation storage technology is being conducted, there is a hologram recording technology that records digital information using holography.

  As a hologram recording technique, for example, there is JP-A-2004-272268 (Patent Document 1). In this publication, a signal beam is condensed on an optical information recording medium by a lens, and simultaneously, a hologram is recorded by irradiating and collimating a reference beam of a parallel beam, and further determining the incident angle of the reference beam on the optical recording medium. A so-called angle multiplex recording method is described in which multiplex recording is performed by displaying different page data on a spatial light modulator while changing. Furthermore, in this publication, the distance between adjacent holograms can be shortened by condensing the signal light with a lens and providing an aperture (spatial filter) in the beam waist, which is compared with the conventional angle multiplex recording system. A technique for increasing the recording density / capacity is described.

  Further, as a hologram recording technique, for example, there is WO2004-102542 (Patent Document 2). In this publication, in one spatial light modulator, light from an inner pixel is signal light, light from an outer ring-shaped pixel is reference light, and both light beams are condensed on an optical recording medium with the same lens. An example is described in which a shift multiplexing method is used in which a hologram is recorded by causing signal light and reference light to interfere with each other in the vicinity of the focal plane of the lens.

  As an encoding method for hologram recording as described above, there is, for example, Japanese Patent Laid-Open No. 9-197947 (Patent Document 3). This publication discloses a hologram recording two-dimensional encoding method for determining information to be recorded by passing at least one light wave through a two-dimensional spatial light modulator. A two-dimensional code for recording holograms, wherein one-fourth of the number of pixels constituting each pair is transmitted through one-fourth of the pixels and three-fourths of the pixels are blocked. Is described.

JP 2004-272268 A WO2004-102542 JP-A-9-197947

  Incidentally, the size of the hologram recorded on the optical recording medium in the method of Patent Document 1 or Patent Document 2 depends on the pixel pitch of the spatial light modulator, and the pixel pitch of the spatial light modulator is set to increase the density. On the other hand, there is a problem that the hologram size becomes large and it is difficult to increase the density. Further, when the pixel pitch of the photodetector is small at the time of reproduction, there is a problem that sufficient reproduction cannot be performed on the reproduced image, and readout accuracy deteriorates. An object of the present invention is to provide a two-dimensional encoding method capable of realizing high density and improving read accuracy by reducing the hologram size without changing the pixel pitch of the spatial light modulator. There is to do.

  The above object can be achieved by, for example, the structure of the claims.

  According to the present invention, in recording digital information using holography, it is possible to change the hologram size without changing the pixel pitch of the spatial light modulator. It is also possible to change the size of the minimum pattern of ON / OFF pixels of the two-dimensional spatial light modulator.

Schematic diagram showing an embodiment of an optical information recording / reproducing apparatus Schematic showing an embodiment of a pickup in an optical information recording / reproducing apparatus A flowchart showing an example of an operation flow of the optical information recording / reproducing apparatus. A flowchart showing an example of a detailed operation flow at the time of data recording of the optical information recording / reproducing apparatus. A flowchart showing an example of a detailed operation flow at the time of data reproduction of the optical information recording / reproducing apparatus. The figure showing the Example of the two-dimensional pattern used at the time of the encoding of an optical information recording / reproducing apparatus The figure showing the Example about the shape of the spatial filter of an optical information recording / reproducing apparatus The figure showing the Example of the two-dimensional pattern used at the time of the encoding of an optical information recording / reproducing apparatus The figure showing the Example about the shape of the spatial filter of an optical information recording / reproducing apparatus A flowchart showing an example of a detailed operation flow at the time of data recording of the optical information recording / reproducing apparatus. The figure showing the prior art example of the two-dimensional pattern used at the time of the encoding of an optical information recording / reproducing apparatus The figure showing the example which doubled the pixel pitch of the two-dimensional pattern used at the time of the encoding of an optical information recording / reproducing apparatus

  Examples of the present invention will be described below.

  FIG. 1 shows the overall configuration of an optical information recording / reproducing apparatus that records and / or reproduces digital information using holography.

  The optical information recording / reproducing apparatus 10 includes a pickup 11, a phase conjugate optical system 12, a disk cure optical system 13, a disk rotation angle detection optical system 14, and a rotation motor 50, and the optical information recording medium 1 is driven by the rotation motor 50. It has a rotatable structure.

  The pickup 11 plays a role of emitting reference light and signal light to the optical information recording medium 1 and recording digital information using holography.

  At this time, an information signal to be recorded is sent by a controller 89 to a spatial light modulator (to be described later) in the pickup 11 via a signal generation circuit 86, and the signal light is modulated by the spatial light modulator.

  When reproducing the information recorded on the optical information recording medium 1, the phase conjugate light of the reference light emitted from the pickup 11 is generated by the phase conjugate optical system 12. Here, the phase conjugate light is a light wave that travels in the opposite direction while maintaining the same wavefront as the input light. Reproduced light reproduced by the phase conjugate light is detected by a photodetector described later in the pickup 11, and a signal is reproduced by a signal processing circuit 85.

  The irradiation time of the reference light and the signal light applied to the optical information recording medium 1 can be adjusted by controlling the shutter opening / closing time (described later) in the pickup 11 via the shutter control circuit 87 by the controller 89.

  The disk cure optical system 13 plays a role of generating a light beam used for pre-cure and post-cure of the optical information recording medium 1. Here, the pre-cure is a pre-process in which, when information is recorded at a desired position in the optical information recording medium 1, a predetermined light beam is irradiated in advance before the reference light and signal light are irradiated to the desired position. is there. The post-cure is a post-process for irradiating a predetermined light beam after recording information at a desired position in the optical information recording medium 1 so that additional recording cannot be performed at the desired position.

  The disk rotation angle detection optical system 14 is used to detect the rotation angle of the optical information recording medium 1. When adjusting the optical information recording medium 1 to a predetermined rotation angle, a signal corresponding to the rotation angle is detected by the disk rotation angle detection optical system 14, and a disk rotation motor control circuit is detected by the controller 89 using the detected signal. The rotation angle of the optical information recording medium 1 can be controlled via 88.

  A predetermined light source driving current is supplied from the light source driving circuit 82 to the light sources in the pickup 11, the disk cure optical system 13, and the disk rotation angle detection optical system 14, and each light source emits a light beam with a predetermined light quantity. be able to.

  The pickup 11, the phase conjugate optical system 12, and the disk cure optical system 13 are provided with a mechanism capable of sliding the position in the radial direction of the optical information recording medium 1, and the position is controlled via the access control circuit 81. .

  By the way, since the recording technique using holography is a technique capable of recording ultra-high-density information, for example, an allowable error with respect to the inclination or displacement of the optical information recording medium 1 tends to be extremely small. Therefore, a mechanism is provided in the pickup 11 to detect the amount of deviation due to a small allowable error, such as the tilt or positional deviation of the optical information recording medium 1, and the servo signal generation circuit 83 outputs a servo control signal. A servo mechanism for generating and correcting the deviation amount via the servo control circuit 84 may be provided in the optical information recording / reproducing apparatus 10.

  The pickup 11, the phase conjugate optical system 12, the disk cure optical system 13, and the disk rotation angle detection optical system 14 may be simplified by combining several optical system configurations or all optical system configurations.

  FIG. 2 shows an example of the optical system configuration of the pickup 11 in the optical information recording / reproducing apparatus 10.

  The light beam emitted from the light source 301 passes through the collimator lens 302 and enters the shutter 303. When the shutter 303 is open, after the light beam passes through the shutter 303, the optical element 304 composed of, for example, a half-wave plate or the like causes the light quantity ratio of P-polarized light and S-polarized light to become a desired ratio. After the polarization direction is controlled, the light enters a PBS (Polarization Beam Splitter) prism 305.

  The light beam transmitted through the PBS prism 305 is expanded by the beam expander 309 and then enters the spatial light modulator 308 via the phase mask 311, the relay lens 310, and the PBS prism 307.

  The signal light beam to which information is added by the spatial light modulator 308 passes through the PBS prism 307 and propagates through the relay lens 312 and the spatial filter 313. Thereafter, the signal light beam is focused on the optical information recording medium 1 by the objective lens 325.

  On the other hand, the light beam reflected by the PBS prism 305 functions as a reference light beam, and is set to a predetermined polarization direction according to recording or reproduction by the polarization direction conversion element 324, and then galvano-coupled via the mirror 314 and the mirror 315. Incident on the mirror 316. Since the angle of the galvanometer mirror 316 can be adjusted by the actuator 317, the incident angle of the reference light beam incident on the information recording medium 1 after passing through the lens 319 and the lens 320 can be set to a desired angle.

  In this way, the signal light beam and the reference light beam are incident on the optical information recording medium 1 so as to overlap each other, whereby an interference fringe pattern is formed in the recording medium, and information is written by writing this pattern on the recording medium. Record. In addition, since the incident angle of the reference light beam incident on the optical information recording medium 1 can be changed by the galvanometer mirror 316, recording by angle multiplexing is possible.

  When reproducing the recorded information, the reference light beam is incident on the optical information recording medium 1 as described above, and the light beam transmitted through the optical information recording medium 1 is reflected by the galvanometer mirror 321 so that its phase conjugate. Produce light.

  The reproduced light beam reproduced by the phase conjugate light propagates through the objective lens 325, the relay lens 312 and the spatial filter 313. Thereafter, the reproduction light beam is reflected by the PBS prism 307 and enters the photodetector 318, and the recorded signal can be reproduced.

  The optical system configuration of the pickup 11 is not limited to that shown in FIG.

  FIG. 3 shows an operation flow of recording and reproduction in the optical information recording / reproducing apparatus 10. Here, a flow relating to recording / reproduction using holography in particular will be described.

  FIG. 3A shows an operation flow from the insertion of the optical information recording medium 1 into the optical information recording / reproducing apparatus 10 until the preparation for recording or reproduction is completed, and FIG. FIG. 3C shows an operation flow until information is recorded on the information recording medium 1, and FIG. 3C shows an operation flow until the information recorded on the optical information recording medium 1 is reproduced from the ready state.

  When a medium is inserted as shown in FIG. 3A (S301), the optical information recording / reproducing apparatus 10 discriminates whether or not the inserted medium is a medium for recording or reproducing digital information using holography, for example. (S302).

  As a result of disc discrimination, when it is determined that the optical information recording medium records or reproduces digital information using holography, the optical information recording / reproducing apparatus 10 reads control data provided on the optical information recording medium, for example, Information relating to the optical information recording medium and information relating to various setting conditions during recording and reproduction, for example, are acquired (S303).

  After reading out the control data, various adjustments according to the control data and learning processing related to the pickup 11 are performed (S304), and the optical information recording / reproducing apparatus 10 is ready for recording or reproduction (S305).

  As shown in FIG. 3B, the operation flow from the ready state to recording of information is as follows. First, data to be recorded is received and information corresponding to the data is sent to the spatial light modulator in the pickup 11 ( S306).

  After that, various learning processes are performed in advance as necessary so that high-quality information can be recorded on the optical information recording medium (S307), and the pickup 11 and the disc are repeated while repeating the seek operation (S308) and the address reproduction (S309). The position of the cure optical system 13 is arranged at a predetermined position on the optical information recording medium.

  Thereafter, a predetermined area is pre-cured using a light beam emitted from the disk cure optical system 13 (S310), and data is recorded using reference light and signal light emitted from the pickup 11 (S311).

  After the data is recorded, the data is verified as necessary (S312), and post-cure is performed using the light beam emitted from the disk Cure optical system 13 (S313).

  As shown in FIG. 3C, the operation flow from the ready state to the reproduction of recorded information is performed in advance with various learning processes as necessary so that high-quality information can be reproduced from the optical information recording medium. (S314). Thereafter, the positions of the pickup 11 and the phase conjugate optical system 12 are arranged at predetermined positions on the optical information recording medium while repeating the seek operation (S315) and the address reproduction (S316).

  Thereafter, reference light is emitted from the pickup 11 and information recorded on the optical information recording medium is read (S317).

  Here, the encoding method in the present embodiment will be described with reference to FIGS. FIG. 4 shows the detailed operation flow of S306 in FIG. 3B, and FIG. 5 shows the detailed operation flow of S317 in FIG.

  First, the detailed operation during recording will be described. When the signal generation circuit 86 receives one page of recording data (S401), the data string is scrambled (S402) and then an error correction code such as Reed-Solomon is added (S403). This scrambling is performed in order to prevent the same pattern from continuing by preventing the data “0” and “1” from continuing, but it is not always necessary. Next, “0” of this data is set as an OFF pixel and “1” is set as an ON pixel (or vice versa), and a two-dimensional pattern of n × m (n, m: natural number) is assigned for each N (N: natural number) bit. These are arranged in order and repeated for the page data to form two-dimensional data for one page (S404). As an example, a two-dimensional pattern of n = m = 4 is shown in FIG. In this example, white is shown as an ON pixel, and black is shown as an OFF pixel, but the reverse is also possible. The same applies to other figures. A marker serving as a reference at the time of reproduction is added to the two-dimensional data configured as described above (S405), and the data is transferred to the spatial light modulator 308 (S406). In the spatial light modulator 308, information is added to the signal light by processing the ON pixels as transmissive and the OFF pixels as non-transmissive.

  Next, the detailed operation during reproduction will be described. First, the image data acquired from the photodetector 318 is transferred to the signal processing circuit 85 (S501). The image position is detected based on the image marker (S502), distortion such as image tilt, magnification, and distortion is corrected (S503), and binarization processing is performed on the corrected image (S504) to remove the marker. By doing (S505), two-dimensional data is acquired (S506). After that, the two-dimensional data is demodulated into one-dimensional data through the reverse process of recording, and the original data is obtained by performing error correction processing (S507) and descrambling processing (S508) (S509).

  Although the detailed operation at the time of recording described above is not performed in S306 in FIG. 3B, the order is not limited as long as recording is possible, such as in S311 depending on the operation of the drive. . The same applies to the detailed operation during reproduction.

  What is characteristic among the recording / reproducing operations of the present embodiment described above is the two-dimensional pattern shown in FIG. 6A or 6B used in the two-dimensional encoding (S404). The feature of this pattern is that the lower limit value of the continuous number of ON / OFF pixels in the arrangement in one direction is restricted so that K (K ≧ 2, K: natural number). For example, when K = 2, the lower limit of the number of consecutive pixels is 2 pixels, so the number of ON / OFF pixel sequences in the array is 2 pixels, 3 pixels, 4 pixels, etc. 1 pixel is excluded. Similarly, when K = 3, the lower limit of the number of continuous pixels is 3 pixels, so the number of continuous ON / OFF pixels in the array is 3 pixels, 4 pixels, 5 pixels, ... And those with 1 pixel and 2 pixels are excluded.

According to this pattern, since there is no pattern in which only one pixel is isolated, the influence of inter-pixel interference during reproduction is reduced, reading accuracy is improved, and the hologram size in the recording medium can be reduced to 1 / K times. It becomes possible. The reason for this will be described later. In general, the size of a hologram recorded in a hologram recording medium is expressed by the following equation 1, which is found to be inversely proportional to the pixel size of the spatial light modulator.
L = f · λ / Δ ·········································································· L Focal length λ: Wavelength of light source (FIG. 2, 301) Δ: Pixel size of spatial light modulator (FIG. 2, 308) As the hologram size increases, it becomes difficult to increase the density. Is better. Therefore, in the example of FIG. 6A or 6B of this embodiment, the lower limit value of the ON / OFF pixel continuous number in the array with respect to one direction is set to K (in FIG. 6, K = 2 in the horizontal direction). The typical pixel size is K times. As a result, the hologram size can be reduced to 1 / K times from Equation 1, and the interval between adjacent holograms can be reduced to 1 / K times. As a result, the entire disk can be increased in density by K times. Here, there is a problem that the number of pattern combinations is limited due to the restriction that the lower limit value of the number of consecutive pixels is K. However, the density becomes higher than the conventional one by increasing the density by K times. A specific example with K = 2 will be described below. First, the two-dimensional pattern that is generally used is restricted to make the ON pixel ratio in the pattern constant in order to make the light quantity of the hologram to be recorded constant. FIG. 11A shows a 4 × 4 pattern that has been conventionally used. In this example, the ON pixel ratio is 4/16. For the sake of simplicity, taking the 1 × 16 pattern of FIG. 11B as an example, in FIG. 11, since 4 bits are selected from 16 bits, there are ₁₆ C ₄ = 1820 ways, so there are 10 bits (2 ¹⁰ = 1024), and the encoding efficiency is 10/16 = 0.625. On the other hand, in the pattern of FIG. 6 of the present embodiment, since the pattern in which 1 bit is isolated is excluded, 79 patterns (excluding those having 1 bit at the end) are provided, and only 6 bits (2 ⁶ = 64 patterns) are assigned. Therefore, the encoding efficiency is 6/16 = 0.375. However, since the pattern of FIG. 6 can double the density due to the constraint of K = 2, the substantial coding efficiency is 0.375 × 2 = 0.75, which is higher than the conventional one. Become. Note that this difference becomes more prominent when the ON pixel ratio is high, and this difference becomes even more prominent by increasing the encoding unit from the 16 bits in the example. In this way, by applying the present embodiment, it is possible to realize a substantial encoding efficiency of 1 or more. Incidentally, even if the actual pixel pitch is multiplied by K as shown in FIG. 12, the hologram size naturally becomes 1 / K times, but there are only ₈ C ₂ = 28 combinations of patterns, so that encoding is performed. The efficiency is bad and cannot exceed the conventional efficiency. This is because, when the pixel pitch is doubled, the possible patterns exist only in multiples of 2 times, 4 times, 8 times, 10 times,... 2 of the original pixel size. This is because only the lower limit value of 2 is restricted, so that it is possible to exist 2 times, 3 times, 4 times, 5 times,.

  Further, when the present embodiment is applied, the hologram size becomes 1 / K times, so that the shape of the spatial filter 313 needs to be changed accordingly. The hologram size is actually determined because of the spatial filter. An example with K = 2 is shown in FIG. FIG. 7A shows a conventional spatial filter, but when this embodiment is applied, it is desirable to make the length 1 / K times in the direction in which the lower limit value of the number of consecutive pixels is set as shown in FIG. 7B. . However, the spatial filter shown here is an example and is not limited to this shape.

  The drive configuration / operation described above is an example, and can be applied not only to the angle multiplexing method described above but also to a different method such as a shift multiplexing method, and is not limited to the described configuration. Absent. Furthermore, although the patterns of FIGS. 6A and 6B are 4 × 4 and 1 × 16, the present invention is not limited to this, and can be realized with an n × m pattern as described above. The direction in which the lower limit value of the number of continuous pixels is set may be the vertical direction or the horizontal direction. The same applies to the following embodiments.

  The difference from the first embodiment is the configuration of the two-dimensional pattern and the shape of the spatial filter 313 in S404.

  In contrast to the first embodiment in which the lower limit value for the number of consecutive pixels is set to one direction, the present embodiment is characterized in that the lower limit value for the number of consecutive pixels is set in both directions. FIG. 8A shows an example of a two-dimensional pattern when applied in both directions. The lower limit value of the continuous number of ON / OFF pixels in the array for one direction is K (K ≧ 2, K: natural number), and the lower limit value of the continuous number of ON / OFF pixels in the array in the direction orthogonal thereto is L (L ≧ 2, L : Natural number), the hologram size becomes 1 / (K × L) times, and K × L times higher density is possible. In addition, the shape of the spatial filter 313 is preferably 1 / K times in the horizontal direction and 1 / L times in the vertical direction as compared to before setting the lower limit value of the number of continuous pixels. FIG. 9A shows a conventional example, and FIG. 9B shows an example where K = L = 2.

  However, as described above, the possible combinations are reduced when the restriction is applied, so that the encoding efficiency is deteriorated as compared with the two-dimensional pattern having the same size as the conventional one as shown in FIG.

  Therefore, the size of the two-dimensional pattern to be used is expanded from the original n × m to (n × K) × (m × L), and two-dimensional encoding is performed using K × L pixels as one unit. FIG. 8B shows an example in which K = L = 2 and n = m = 4. As a result, the density can be increased by a factor of K × L = 2 × 2 = 4 times compared to the conventional example of FIG. 11A. However, if the size of the spatial light modulator 308 is not changed, the two-dimensional pattern Since the size is four times, the amount of data that can be recorded is 1/4 times, and the recording density as a whole is not improved.

  However, since the minimum unit of ON / OFF pixels is K × L according to this embodiment, the photodetector 318 reads out an image by K × L times oversampling, which has an effect of improving the reading accuracy. is there.

  This embodiment is characterized in that the two-dimensional encoding method to be used is switched according to conditions.

  For example, the encoding method is switched such that the second embodiment is used for a part that causes a problem such as an address or recording medium information, and the conventional example is used for other areas. It is also effective to switch according to the type of recording medium.

  In this embodiment, since the shape of the opening of the spatial filter needs to be changed in accordance with the switching of the encoding method, the spatial filter 313 is assumed to be composed of a liquid crystal element or the like. However, as long as the purpose of changing the shape or characteristics can be achieved, the spatial filter is not limited to the liquid crystal element, and other methods such as mechanically changing the shape of the opening may be used.

  FIG. 10 shows a detailed operation flow of S306 in FIG. 3B when the switching method of the two-dimensional encoding method is applied. The detailed operation will be described below. First, the type of recording medium to be used or the position currently being processed is detected (S1001), and it is determined whether it is a preset medium or processing position (S1002). The spatial filter 313 is changed to an aperture suitable for the first encoding method (S1003). After that, when the signal generation circuit 86 receives one page of recording data corresponding to the processing of the first encoding method (S1004), the data string is scrambled (S1005) and then error correction such as Reed-Solomon is performed. A code is added (S1006). Next, two-dimensional data is constructed from this data every N bits according to the first encoding method (S1007). A marker serving as a reference at the time of reproduction is added to the two-dimensional data configured as described above (S1013), and the data is transferred to the spatial light modulator 308 (S1014).

  On the other hand, if it differs from the medium or processing position set in advance in S1002, the second encoding method is selected, and then the processing from S1008 to S1014 is performed. These are the same as steps S1003 to S1014 with respect to the first encoding method, in which the first is replaced with the second.

  Similarly, at the time of reproduction, it is determined whether the medium is set in advance or the processing position, and processing is performed by selecting whether to decode using the first encoding method or to decode using the second encoding method. To do.

  Although the detailed operation at the time of recording described above is not performed in S306 in FIG. 3B, the order is not limited as long as recording is possible, such as in S311 depending on the operation of the drive. .

  Although an example in which the shape of the spatial filter 313 is switched by the encoding method has been described here, it is not always necessary to switch depending on the encoding method, and the same spatial filter may be used.

  Further, when the conventional method and the present method are mixed as in the third embodiment, for example, 2-bit data is allocated, the conventional method is assigned to (0, 0), the first method is assigned to (0, 1), (1 1), a flag in the form of the second embodiment is added to each book, page, disc management area, servo layer, etc. for quick playback processing. It will be certain.

DESCRIPTION OF SYMBOLS 1 ... Optical information recording medium, 10 ... Optical information recording / reproducing apparatus, 11 ... Pickup, 12 ... Phase conjugate optical system, 13 ... Disc Cure optical system, 14 ... Disc rotation angle Optical system for detection, 50... Rotation motor, 81... Access control circuit, 82... Light source drive circuit, 83 ... Servo signal generation circuit, 84 ... Servo control circuit, 85. Processing circuit 86 ... Signal generation circuit 87 ... Shutter control circuit 88 ... Disc rotating motor control circuit 89 ... Controller 301 ... Light source 302 ... collimating lens 303 ... ..Shutter, 304 ... optical element, 305 ... polarizing beam splitter, 306 ... signal light, 307 ... polarizing beam splitter, 308 ... spatial light modulator, 309 ... bi Expander, 310 ... relay lens, 311 ... phase mask, 312 ... relay lens, 313 ... spatial filter, 314 ... mirror, 315 ... mirror, 316 ... Mirror, 317 ... Actuator, 318 ... Photodetector, 319 ... Lens, 320 ... Lens, 321 ... Mirror ... 322 ... Actuator, 323 ... Reference light, 324 ..Polarization direction conversion element, 325 ... Objective lens

Claims (30)

An optical information recording medium on which information is recorded,
The optical information recording medium has an encoding method in which the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the arrangement of the spatial light modulator in one direction is K (K ≧ 2, K: natural number). Interference fringes generated when the signal light modulated by the spatial light modulator based on the generated data and the reference light are superimposed are recorded as holograms,
The size of the hologram is a size corresponding to a lower limit value K of the number of consecutive pixels in the encoding method. An optical information recording medium on which information is recorded,
In the optical information recording medium, the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the arrangement of the spatial light modulator in one direction is K (K ≧ 2, K: natural number), orthogonal to the one direction. Is modulated by the spatial light modulator on the basis of data generated by an encoding method in which the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the arrangement with respect to the direction is L (L ≧ 2, L: natural number). Interference fringes generated when signal light and reference light are superimposed are recorded as holograms,
The size of the hologram is a size corresponding to the lower limit values K and L of the number of consecutive pixels in the encoding method. An optical information recording medium on which information is recorded,
The optical information recording medium has an encoding method in which the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the arrangement of the spatial light modulator in one direction is K (K ≧ 2, K: natural number). Interference fringes generated when the signal light modulated by the spatial light modulator based on the generated data and condensed through the objective lens and the reference light are superimposed are recorded as a hologram,
The wavelengths of the signal light and the reference light are λ,
The focal length of the objective lens is f,
When the pixel size of the spatial light modulator is Δ,
The optical information recording medium according to claim 1, wherein the size of the hologram in the one direction is smaller than f · λ / Δ. An optical information recording medium on which information is recorded,
In the optical information recording medium, the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the arrangement of the spatial light modulator in one direction is K (K ≧ 2, K: natural number), orthogonal to the one direction. Is modulated by the spatial light modulator on the basis of data generated by an encoding method in which the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the arrangement with respect to the direction is L (L ≧ 2, L: natural number). The interference fringes generated when the signal light collected through the objective lens and the reference light are superimposed are recorded as holograms,
The wavelengths of the signal light and the reference light are λ,
The focal length of the objective lens is f,
When the pixel size of the spatial light modulator is Δ,
The optical information recording medium according to claim 1, wherein the size of the hologram in the one direction and a direction orthogonal to the one direction is smaller than f · λ / Δ. An optical information recording medium on which information is recorded,
The optical information recording medium has a two-dimensional encoding in which the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in an array of spatial light modulators in one direction is K (K ≧ 2, K: natural number). And a two-dimensional encoding method in which the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array for the one direction is M different from K (M ≧ 1, M: natural number). Interference fringes generated when the signal light modulated by the spatial light modulator based on the data generated by the encoding method for generating data and the reference light are superimposed are recorded as holograms,
An optical information recording medium on which the hologram is recorded by switching between K and M according to a recording area of the optical information recording medium. An optical information recording medium on which information is recorded,
In the optical information recording medium, the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array of spatial light modulators in one direction is defined as K (K ≧ 2, K: natural number), orthogonal L (, L ≧ 2 L: natural number) consecutive number and OFF pixels lower limit of the number of continuous ON pixels in the array relative to the direction of the two-dimensional encoding method to the continuous number of ON pixels in the array with respect to the first direction And the lower limit value of the OFF pixel continuity number is M (M ≧ 1, M: natural number) different from K, and the lower limit value of the ON pixel continuity number and the OFF pixel continuity number in the array with respect to the direction orthogonal to the one direction. The spatial light modulation based on the generated data to generate two-dimensional data by a two-dimensional encoding method with N different from L (N ≧ 1, N: natural number) A modulated signal light in the interference fringes generated when superposing the reference light are recorded as a hologram,
An optical information recording medium on which the hologram is recorded by switching the K and the M and / or the L and the N in accordance with a recording area of the optical information recording medium. An optical information recording apparatus for recording information using holography,
A laser light source for generating signal light and reference light;
A spatial light modulator that modulates the generated signal light;
An objective lens for irradiating the optical signal recording medium with the modulated signal light;
Two-dimensional data is generated by a two-dimensional encoding method in which the lower limit of the number of consecutive ON pixels and the number of consecutive OFF pixels in the array of pixels of the spatial light modulator in one direction is K (K ≧ 2, K: natural number). A signal generator to
A filter for limiting the size of the signal light incident on the optical information recording medium,
The wavelength of the laser light source is λ,
The focal length of the objective lens is f,
When the pixel size of the spatial light modulator is Δ,
The size of the signal light limited by the filter in the one direction is smaller than f · λ / Δ,
Recording the two-dimensional data as a hologram by interference fringes generated when the signal light from the objective lens and the generated reference light are superimposed in the optical information recording medium;
Optical information recording device. An optical information recording apparatus for recording information using holography,
A laser light source for generating signal light and reference light;
A spatial light modulator that modulates the generated signal light;
An objective lens for irradiating the optical signal recording medium with the modulated signal light;
The lower limit value of the number of consecutive ON pixels and the number of consecutive OFF pixels in the array for one direction of the pixels of the spatial light modulator is K (K ≧ 2, K: natural number), and the ON pixels in the array for the direction orthogonal to the one direction A signal generation unit that generates two-dimensional data by a two-dimensional encoding method in which the lower limit of the number of consecutive pixels and the number of consecutive OFF pixels is L (L ≧ 2, L: natural number);
A filter for limiting the size of the signal light incident on the optical information recording medium,
The wavelength of the laser light source is λ,
The focal length of the objective lens is f,
When the pixel size of the spatial light modulator is Δ,
The size of the signal light limited by the filter in the one direction and the direction orthogonal to the one direction is smaller than f · λ / Δ,
Recording the two-dimensional data as a hologram by interference fringes generated when the signal light from the objective lens and the generated reference light are superimposed in the optical information recording medium;
Optical information recording device. An optical information recording method for recording information using holography,
A light generation step of generating signal light and reference light from a laser light source;
A spatial light modulation step of modulating the generated signal light by a spatial light modulator;
An irradiation step of irradiating the modulated signal light to the optical information recording medium via an objective lens;
Two-dimensional data is generated by a two-dimensional encoding method in which the lower limit of the number of consecutive ON pixels and the number of consecutive OFF pixels in the array of pixels of the spatial light modulator in one direction is K (K ≧ 2, K: natural number). Generating a signal step;
A limiting step for limiting the size of the signal light incident on the optical information recording medium;
Recording the two-dimensional data as a hologram by interference fringes generated when the signal light from the objective lens and the generated reference light are superimposed in the optical information recording medium,
The wavelength of the laser light source is λ,
The focal length of the objective lens is f,
When the pixel size of the spatial light modulator is Δ,
In the limiting step, the size of the limited signal light in the one direction is smaller than f · λ / Δ.
Optical information recording method. An optical information recording method for recording information using holography,
A light generation step of generating signal light and reference light from a laser light source;
A spatial light modulation step of modulating the generated signal light by a spatial light modulator;
An irradiation step of irradiating the modulated signal light to the optical information recording medium via an objective lens;
The lower limit value of the number of consecutive ON pixels and the number of consecutive OFF pixels in the array for one direction of the pixels of the spatial light modulator is K (K ≧ 2, K: natural number), and the ON pixels in the array for the direction orthogonal to the one direction A signal generation step of generating two-dimensional data by a two-dimensional encoding method in which the lower limit value of the continuous number and the OFF pixel continuous number is L (L ≧ 2, L: natural number);
A limiting step for limiting the size of the signal light incident on the optical information recording medium;
Recording the two-dimensional data as a hologram by interference fringes generated when the signal light from the objective lens and the generated reference light are superimposed in the optical information recording medium,
The wavelength of the laser light source is λ,
The focal length of the objective lens is f,
When the pixel size of the spatial light modulator is Δ,
In the limiting step, the size of the limited signal light in the one direction and the direction orthogonal to the one direction is smaller than f · λ / Δ.
Optical information recording method. Based on the data generated by the encoding method in which the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array of spatial light modulator pixels in one direction is K (K ≧ 2, K: natural number). An optical information reproducing apparatus for reproducing information from an optical information recording medium in which interference fringes generated when signal light modulated by a spatial light modulator and reference light are superimposed are recorded as a hologram,
A laser light source for generating reference light;
An objective lens that collects reproduction light reproduced by irradiating the hologram with reference light incident on the optical information recording medium;
A filter for limiting the size of the reproduction light collected by the objective lens,
The wavelength of the laser light source is λ,
The focal length of the objective lens is f,
When the pixel size of the spatial light modulator is Δ,
The size of the reproduction light limited by the filter in the one direction is smaller than f · λ / Δ.
An optical information reproducing apparatus characterized by the above. The lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array for one direction of the pixels of the spatial light modulator is K (K ≧ 2, K: natural number), and the ON pixel in the array for the direction orthogonal to the one direction A signal light modulated by the spatial light modulator based on data generated by an encoding method in which the lower limit value of the continuous number and the OFF pixel continuous number is L (L ≧ 2, L: natural number); An optical information reproducing apparatus for reproducing information from an optical information recording medium in which interference fringes generated when the two are superimposed are recorded as holograms,
A laser light source for generating reference light;
An objective lens that collects reproduction light reproduced by irradiating the hologram with reference light incident on the optical information recording medium;
A filter for limiting the size of the reproduction light collected by the objective lens,
The wavelength of the laser light source is λ,
The focal length of the objective lens is f,
When the pixel size of the spatial light modulator is Δ,
The size of the reproduction light limited by the filter in the one direction and the direction orthogonal to the one direction is smaller than f · λ / Δ.
An optical information reproducing apparatus characterized by the above. Based on the data generated by the encoding method in which the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array of spatial light modulator pixels in one direction is K (K ≧ 2, K: natural number). An optical information reproducing method for reproducing information from an optical information recording medium in which interference fringes generated when signal light modulated by a spatial light modulator and reference light are superimposed are recorded as a hologram,
A generation step of generating reference light using a laser light source;
A condensing step for condensing the reproduction light reproduced by irradiating the hologram with the reference light incident on the optical information recording medium, using an objective lens;
A limiting step of limiting the size of the reproduction light collected by the objective lens,
The wavelength of the laser light source is λ,
The focal length of the objective lens is f,
When the pixel size of the spatial light modulator is Δ,
In the limiting step, the size of the limited reproduction light in the one direction is smaller than f · λ / Δ.
An optical information reproducing method characterized by the above. The lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array for one direction of the pixels of the spatial light modulator is K (K ≧ 2, K: natural number), and the ON pixel in the array for the direction orthogonal to the one direction A signal light modulated by the spatial light modulator based on data generated by an encoding method in which the lower limit value of the continuous number and the OFF pixel continuous number is L (L ≧ 2, L: natural number); Is an optical information reproducing method for reproducing information from an optical information recording medium in which interference fringes generated when the two are superimposed as a hologram,
A generation step of generating reference light using a laser light source;
A condensing step for condensing the reproduction light reproduced by irradiating the hologram with the reference light incident on the optical information recording medium, using an objective lens;
A limiting step of limiting the size of the reproduction light collected by the objective lens,
The wavelength of the laser light source is λ,
The focal length of the objective lens is f,
When the pixel size of the spatial light modulator is Δ,
In the limiting step, the size of the limited reproduction light in the one direction and the direction orthogonal to the one direction is smaller than f · λ / Δ.
An optical information reproducing method characterized by the above. An optical information recording apparatus for recording information using holography,
A laser light source for generating signal light and reference light;
A spatial light modulator that modulates the generated signal light;
An objective lens for irradiating the optical signal recording medium with the modulated signal light;
A filter for limiting the size of the signal light incident on the optical information recording medium,
Two-dimensional data is generated by a two-dimensional encoding method in which the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array of pixels in one direction of the spatial light modulator is K (K ≧ 2, K: natural number). And
The wavelength of the laser light source is λ,
The focal length of the objective lens is f,
When the pixel size of the spatial light modulator is Δ,
The size of the signal light limited by the filter in the one direction is smaller than f · λ / Δ,
Recording the two-dimensional data as a hologram by interference fringes generated when the signal light from the objective lens and the generated reference light are superimposed in the optical information recording medium;
Optical information recording device. An optical information recording apparatus for recording information using holography,
A laser light source for generating signal light and reference light;
A spatial light modulator that modulates the generated signal light;
An objective lens for irradiating the optical signal recording medium with the modulated signal light;
A filter for limiting the size of the signal light incident on the optical information recording medium,
The lower limit value of the number of consecutive ON pixels and the number of consecutive OFF pixels in the array for one direction of the pixels of the spatial light modulator is K (K ≧ 2, K: natural number), and the ON pixels in the array for the direction orthogonal to the one direction Two-dimensional data is generated by a two-dimensional encoding method in which the lower limit of the number of consecutive pixels and the number of consecutive OFF pixels is L (L ≧ 2, L: natural number),
The wavelength of the laser light source is λ,
The focal length of the objective lens is f,
When the pixel size of the spatial light modulator is Δ,
The size of the signal light limited by the filter in the one direction and the direction orthogonal to the one direction is smaller than f · λ / Δ,
Recording the two-dimensional data as a hologram by interference fringes generated when the signal light from the objective lens and the generated reference light are superimposed in the optical information recording medium;
Optical information recording device. An optical information recording apparatus for recording information using holography,
A laser light source for generating signal light and reference light;
A spatial light modulator that modulates the generated signal light, and
A two-dimensional encoding method in which the lower limit value of the number of consecutive ON pixels and the number of consecutive OFF pixels in an array in at least one direction of pixels of the spatial light modulator is K (K ≧ 2, K: natural number); Two-dimensional data is generated by a two-dimensional encoding method in which the lower limit value of the number of consecutive ON pixels and the number of consecutive OFF pixels in an array for one direction is M (M ≧ 1, M: natural number) different from K. ,
An optical information recording apparatus that switches between K and M according to an area of an optical information recording medium and / or a type of the optical information recording medium. An optical information recording apparatus for recording information using holography,
A laser light source for generating signal light and reference light;
A spatial light modulator that modulates the generated signal light, and
The lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array of the spatial light modulator in one direction is K (K ≧ 2, K: natural number), and the ON in the array in the direction orthogonal to the one direction. L (L ≧ 2, L: natural number) consecutive number and OFF pixels lower limit of the number of successive pixels and a two-dimensional encoding method to the continuous number and OFF pixels consecutive number of the lower limit of the ON pixels in the array with respect to the first direction The value is M different from K (M ≧ 1, M: natural number), and the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array perpendicular to the one direction is N (different from L). Two-dimensional data is generated by a two-dimensional encoding method in which N ≧ 1, N: natural number),
An optical information recording apparatus that switches between K and M and / or L and N according to a region of an optical information recording medium and / or a type of the optical information recording medium. An optical information recording apparatus for recording information using holography,
A laser light source for generating signal light and reference light;
A spatial light modulator that modulates the generated signal light;
A two-dimensional encoding method in which the lower limit value of the number of consecutive ON pixels and the number of consecutive OFF pixels in an array in at least one direction of pixels of the spatial light modulator is K (K ≧ 2, K: natural number); Two-dimensional data is generated by a two-dimensional encoding method in which the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in an array for one direction is M different from K (M ≧ 1, M: natural number). A signal generation unit,
The signal generator may be an optical information recording medium area and / or a type of optical information recording medium,
An optical information recording apparatus that switches between K and M. An optical information recording apparatus for recording information using holography,
A laser light source for generating signal light and reference light;
A spatial light modulator that modulates the generated signal light;
The lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array of the spatial light modulator in one direction is K (K ≧ 2, K: natural number), and the ON in the array in the direction orthogonal to the one direction. L (L ≧ 2, L: natural number) consecutive number and OFF pixels lower limit of the number of successive pixels and a two-dimensional encoding method to the continuous number and OFF pixels consecutive number of the lower limit of the ON pixels in the array with respect to the first direction The value is M different from K (M ≧ 1, M: natural number), and the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array perpendicular to the one direction is N (different from L). N ≧ 1, N: natural number), and a signal generation unit for generating two-dimensional data by the two-dimensional encoding method,
The signal generator may be an optical information recording medium area and / or a type of optical information recording medium,
An optical information recording apparatus for switching between K and M and / or L and N. The optical information recording apparatus according to claim 19 or 20 ,
A filter for limiting the size of the signal light incident on the optical information recording medium,
An optical information recording apparatus that switches the characteristics of the filter in accordance with a lower limit value of the number of consecutive pixels. A two-dimensional encoding method in which the lower limit value of the number of consecutive ON pixels and the number of consecutive OFF pixels in an array with respect to at least one direction of pixels of the spatial light modulator is K (K ≧ 2, K: natural number); A two-dimensional encoding method in which the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array with respect to the direction is set to M (M ≧ 1, M: natural number) different from K. Optical information reproducing apparatus for reproducing information from an optical information recording medium on which the two-dimensional data is hologram-recorded by interference fringes generated when signal light modulated by the spatial light modulator and reference light are superimposed on each other Because
A laser light source for generating reference light;
A photodetector for detecting signal light reproduced by irradiating the optical information recording medium with the generated reference light, and
An optical information reproducing apparatus in which information is recorded on the optical information recording medium by switching the K and the M according to the area of the optical information recording medium and / or the type of the optical information recording medium. The lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array for one direction of the spatial light modulator is K (K ≧ 2, K: natural number), and the ON pixels in the array for the direction orthogonal to the one direction. A two-dimensional encoding method in which L (L ≧ 2, L: natural number) is a lower limit value of the continuous number of pixels and the OFF pixel continuous number, and a lower limit value of the continuous number of ON pixels and the consecutive number of OFF pixels in the array with respect to the one direction Is M different from K (M ≧ 1, M: natural number), and the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array with respect to the direction orthogonal to the one direction is N (N ≧ 1, N: natural number), and the signal light modulated by the spatial light modulator based on the two-dimensional data generated by the two-dimensional data is overlapped with the reference light Wherein the interference fringes occurring when was Align 2-dimensional data is an optical information reproducing apparatus for reproducing information from the optical information recording medium is a hologram recording,
A laser light source for generating reference light;
A photodetector for detecting signal light reproduced by irradiating the optical information recording medium with the generated reference light, and
In the optical information recording medium, information is recorded by switching between K and M and / or L and N according to the area of the optical information recording medium and / or the type of the optical information recording medium. An optical information reproducing apparatus. The optical information reproducing apparatus according to claim 22 or 23 ,
A filter for limiting the size of the signal light incident on the optical information recording medium,
An optical information reproducing apparatus that switches the characteristics of the filter in accordance with a lower limit value of the number of consecutive pixels that are switched. An optical information recording method for recording information,
A light generation step for generating signal light;
A spatial light modulation step for modulating the signal light generated in the light generation step;
An irradiation step of irradiating the optical information recording medium with the signal light modulated in the spatial light modulation step;
A two-dimensional encoding method in which the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array in at least one direction of the pixels in the spatial light modulation step is K (K ≧ 2, K: natural number); Two-dimensional data is generated by a two-dimensional encoding method in which the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in an array for one direction is M different from K (M ≧ 1, M: natural number). And a signal generation step,
The optical information recording method, wherein in the signal generation step, the K and the M are switched according to the area of the optical information recording medium and / or the type of the optical information recording medium. An optical information recording method for recording information,
A light generation step for generating signal light;
A spatial light modulation step for modulating the signal light generated in the light generation step;
An irradiation step of irradiating the optical information recording medium with the signal light modulated in the spatial light modulation step;
The lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array for one direction of pixels in the spatial light modulation step is K (K ≧ 2, K: natural number), and ON in the array orthogonal to the one direction. L (L ≧ 2, L: natural number) consecutive number and OFF pixels lower limit of the number of successive pixels and a two-dimensional encoding method to the continuous number and OFF pixels consecutive number of the lower limit of the ON pixels in the array with respect to the first direction The value is M different from K (M ≧ 1, M: natural number), and the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array perpendicular to the one direction is N (different from L). N ≧ 1, N: natural number), and a signal generation step for generating two-dimensional data by
The optical information recording method, wherein, in the signal generation step, the K and the M and / or the L and the N are switched according to the area of the optical information recording medium and / or the type of the optical information recording medium. In the optical information recording method according to claim 25 or 26 ,
A limiting step of limiting the size of the signal light incident on the optical information recording medium to a size according to a lower limit value of the number of consecutive pixels generated by the signal generating step;
An optical information recording method, wherein the characteristic of the limiting step is switched according to a lower limit value of the number of pixel continuations switched. A two-dimensional encoding method in which the lower limit value of the number of consecutive ON pixels and the number of consecutive OFF pixels in an array with respect to at least one direction of pixels of the spatial light modulator is K (K ≧ 2, K: natural number); A two-dimensional encoding method in which the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array with respect to the direction is set to M (M ≧ 1, M: natural number) different from K. Optical information reproducing method for reproducing information from an optical information recording medium on which the two-dimensional data is hologram-recorded by interference fringes generated when the signal light modulated by the spatial light modulator and the reference light are superimposed on each other Because
A light generating step for generating a reference light;
A condensing step of condensing reproduction light reproduced by irradiating the optical information recording medium with reference light, and
An optical information reproducing method in which information is recorded on the optical information recording medium by switching the K and the M according to the area of the optical information recording medium and / or the type of the optical information recording medium. The lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array for one direction of the spatial light modulator is K (K ≧ 2, K: natural number), and the ON pixels in the array for the direction orthogonal to the one direction. A two-dimensional encoding method in which L (L ≧ 2, L: natural number) is a lower limit value of the continuous number of pixels and the OFF pixel continuous number, and a lower limit value of the continuous number of ON pixels and the consecutive number of OFF pixels in the array with respect to the one direction Is M different from K (M ≧ 1, M: natural number), and the lower limit value of the continuous number of ON pixels and the continuous number of OFF pixels in the array with respect to the direction orthogonal to the one direction is N (N ≧ 1, N: natural number), and the signal light modulated by the spatial light modulator based on the two-dimensional data generated by the two-dimensional data is overlapped with the reference light Wherein the interference fringes occurring when was Align 2-dimensional data is an optical information reproducing method for reproducing information from the optical information recording medium is a hologram recording,
A light generating step for generating a reference light;
A condensing step of condensing reproduction light reproduced by irradiating the optical information recording medium with reference light, and
In the optical information recording medium, information is recorded by switching between K and M and / or L and N according to the area of the optical information recording medium and / or the type of the optical information recording medium. An optical information reproduction method. The optical information reproducing method according to claim 28 or 29, depending on the lower limit of the number of continuous pixels is switched, limits the size of the signal light incident on the optical information recording medium switching the characteristic of the filter, the optical information reproducing method .

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