JP4108661B2 - Optical information recording method and optical information reproducing method - Google Patents

Description

  The present invention relates to an optical information recording method for recording information on an optical information recording medium using holography, and particularly to an optical information reproducing method for reproducing information from an optical information recording medium using holography.

  Holographic recording, in which information is recorded on a recording medium using holography, is generally performed by superimposing light having image information and reference light inside the recording medium, and forming the interference fringes formed at that time on the recording medium. Done by writing. At the time of reproducing the recorded information, the image information is reproduced by diffraction by interference fringes by irradiating the recording medium with reference light.

  In recent years, volume holography, particularly digital volume holography, has been developed and attracted attention for practical use for ultra-high density optical recording. Volume holography is a method of writing interference fringes in three dimensions by actively utilizing the thickness direction of the recording medium. Increasing the thickness increases the diffraction efficiency and increases the recording capacity using multiple recording. There is a feature that can be planned. Digital volume holography is a computer-oriented holographic recording method that uses a recording medium and a recording method similar to those of volume holography, but restricts image information to be recorded to a binarized digital pattern. In this digital volume holography, for example, image information such as an analog picture is once digitized, developed into two-dimensional digital pattern information, and recorded as image information. At the time of reproduction, the digital pattern information is read and decoded so that the original image information is restored and displayed. As a result, even if the S / N ratio (signal to noise ratio) is somewhat poor at the time of reproduction, the original information is reproduced very faithfully by performing differential detection or encoding binary data and performing error correction. It becomes possible.

FIG. 75 is a perspective view showing a schematic configuration of a recording / reproducing system in conventional digital volume holography. This recording / reproducing system condenses the spatial light modulator 101 that generates information light 102 based on the two-dimensional digital pattern information, and the information light 102 from the spatial light modulator 101 to the hologram recording medium 100. A lens 103 for irradiation, a reference light irradiation means (not shown) for irradiating the hologram recording medium 100 with reference light 104 from a direction substantially orthogonal to the information light 102, and reproduced two-dimensional digital pattern information are detected. A CCD (Charge Coupled Device) array 107 and a lens 106 that collects the reproduction light 105 emitted from the hologram recording medium 100 and irradiates the light onto the CCD array 107. For the hologram recording medium 100, a crystal such as LiNbO ₃ is used.

  In the recording / reproducing system shown in FIG. 75, at the time of recording, information such as an original image to be recorded is digitized, and two-dimensional digital pattern information is generated by further arranging the 0 or 1 signal in two dimensions. One two-dimensional digital pattern information is called page data. Here, it is assumed that page data # 1 to #n are multiplexed and recorded on the same hologram recording medium 100. In this case, first, spatially modulated information light 102 is generated by selecting whether the light is transmitted or blocked for each pixel by the spatial light modulator 101 based on the page data # 1, and passes through the lens 103. The hologram recording medium 100 is irradiated. At the same time, the hologram recording medium 100 is irradiated with the reference light 104 from a direction θ1 substantially orthogonal to the information light 102, and interference fringes formed by superimposing the information light 102 and the reference light 104 inside the hologram recording medium 100 are formed. Record. In order to increase the diffraction efficiency, the reference beam 104 is deformed into a flat beam by a cylindrical lens or the like so that the interference fringes are recorded over the thickness direction of the hologram recording medium 100. At the time of recording the next page data # 2, the reference beam 104 is irradiated from an angle θ2 different from θ1, and the reference beam 104 and the information beam 102 are overlapped to multiplex-record information on the same hologram recording medium 100. can do. Similarly, when recording the other page data # 3 to #n, the reference beam 104 is irradiated from different angles θ3 to θn, and information is multiplexed and recorded. A hologram in which information is multiplexed and recorded is called a stack. In the example shown in FIG. 75, the hologram recording medium 100 has a plurality of stacks (stack 1, stack 2,..., Stack m,...).

  In order to reproduce arbitrary page data from the stack, it is only necessary to irradiate the stack with reference light 104 having the same incident angle as when the page data was recorded. Then, the reference light 104 is selectively diffracted by the interference fringes corresponding to the page data, and the reproduction light 105 is generated. The reproduction light 105 enters the CCD array 107 via the lens 106, and the two-dimensional pattern of the reproduction light is detected by the CCD array 107. Then, the information such as the original image is reproduced by decoding the detected two-dimensional pattern of the reproduction light in reverse to the recording.

  In the configuration shown in FIG. 75, information can be multiplexed and recorded on the same hologram recording medium 100. However, in order to record information at an extremely high density, positioning of the information beam 102 and the reference beam 104 with respect to the hologram recording medium 100 is performed. Becomes important. However, in the configuration shown in FIG. 75, since there is no information for positioning in the hologram recording medium 100 itself, the positioning of the information beam 102 and the reference beam 104 with respect to the hologram recording medium 100 can only be performed mechanically and has high accuracy. Positioning is difficult. Therefore, the removability (ease of moving the hologram recording medium from one recording / reproducing apparatus to another recording / reproducing apparatus and performing the same recording / reproducing) is difficult, and random access is difficult and high-density recording is difficult. There is a problem that it is. Further, in the configuration shown in FIG. 75, since the optical axes of the information beam 102, the reference beam 104, and the reproduction beam 105 are arranged at spatially different positions, the optical system for recording or reproduction is increased in size. There is a problem of doing.

  Further, when the two-dimensional pattern of the reproduction light 105 is detected by the CCD array 107, some reference for recognizing the two-dimensional pattern is necessary.

  An object of the present invention is to provide an optical information recording apparatus for recording information on an optical information recording medium using holography or an optical information reproducing apparatus for reproducing information from an optical information recording medium using holography. It is an object of the present invention to provide an optical information recording method and an optical information reproducing method that facilitate recognition.

  Another object of the present invention is to provide an optical information recording method for recording information on an optical information recording medium using holography that enables a recording or reproducing optical system to be configured to be small, and to use holography. An object of the present invention is to provide an optical information reproducing method for reproducing information from an optical information recording medium.

  In order to achieve the above-described object, the optical information recording method of the present invention is an optical information recording method for recording information on an optical information recording medium having an information recording layer on which information is recorded using holography. Generating information light carrying information by spatially modulating the light beam emitted from the light source according to the two-dimensional pattern information, and generating the recording reference light using the light beam emitted from the light source, The information recording layer is irradiated with the information light and the recording reference light so that information is recorded on the information recording layer by an interference pattern due to interference between the information light and the recording reference light. The two-dimensional pattern information includes reference position information indicating a reference position of the two-dimensional pattern information.

  Further, in the optical information recording method, the information light and the recording reference light may be arranged such that the optical axis of the information light and the optical axis of the recording reference light are on the same line from the same surface side of the information recording layer. It is preferable to irradiate so that it may be located.

  Further, in the optical information recording method, the reference position information may be constituted by a two-dimensional pattern serving as error data as a two-dimensional pattern of information to be recorded.

  Also, the optical information reproducing method of the present invention provides an information recording layer in which information is recorded by an interference pattern due to interference between information light carrying information and recording reference light by spatially modulating with two-dimensional pattern information. An optical information reproduction method for reproducing information from a provided optical information recording medium using holography, wherein reproduction reference light is generated using a light beam emitted from a light source, and the reproduction is performed on the information recording layer. Reference position information indicating a reference position included in the two-dimensional pattern information of the reproduction light by irradiating the reference light for detection, detecting the reproduction light generated from the information recording layer when the reproduction reference light is irradiated To recognize the reference position of the reproduction light.

  Furthermore, in the optical information reproducing method, the reproducing light is transmitted from the same surface side as the reproducing reference light incident side of the optical information recording medium from the optical axis of the reproducing light and the optical axis of the reproducing reference light. Are preferably emitted so as to be positioned on the same line.

  Further, in the optical information reproducing method, the reference position information may be constituted by a two-dimensional pattern that becomes error data as a two-dimensional pattern of information to be reproduced.

  According to the optical information recording method and the optical information reproducing method of the present invention, the reference position information indicating the reference position in the reproduction light pattern is included in the information light, so that the reproduction light pattern can be easily recognized. .

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The first embodiment of the present invention is an example that enables multiple recording by phase encoding multiplexing. FIG. 1 is an explanatory diagram showing a configuration of a pickup device (hereinafter simply referred to as a pickup) in an optical information recording / reproducing apparatus according to the present embodiment and an optical information recording medium in the present embodiment, and FIG. It is a block diagram which shows the whole structure of the optical information recording / reproducing apparatus which concerns on a form. The optical information recording / reproducing apparatus includes an optical information recording apparatus and an optical information reproducing apparatus.

  First, the configuration of the optical information recording medium in the present embodiment will be described with reference to FIG. The optical information recording medium 1 includes a hologram layer 3 as an information recording layer on which information is recorded using volume holography on one surface of a disc-shaped transparent substrate 2 made of polycarbonate or the like, a reflective film 5, The protective layer 4 is laminated in this order. At the boundary surface between the hologram layer 3 and the protective layer 4, there are provided a plurality of positioning area address / servo areas 6 extending linearly in the radial direction at predetermined angular intervals, and between adjacent address / servo areas 6. A sector section is a data area 7. In the address / servo area 6, information for performing focus servo and tracking servo by the sampled servo method and address information are recorded in advance by embossed pits or the like. The focus servo can be performed using the reflection surface of the reflection film 5. As information for performing the tracking servo, for example, a wobble pit can be used. The transparent substrate 2 has an appropriate thickness of 0.6 mm or less, for example, and the hologram layer 3 has an appropriate thickness of 10 μm or more, for example. The hologram layer 3 is formed of a hologram material whose optical characteristics such as a refractive index, a dielectric constant, and a reflectance change according to the light intensity when irradiated with light. As the hologram material, for example, a photopolymer HRF-600 (product name) manufactured by DuPont is used. The reflective film 5 is made of aluminum, for example.

  Next, the configuration of the optical information recording / reproducing apparatus according to the present embodiment will be described with reference to FIG. The optical information recording / reproducing apparatus 10 includes a spindle 81 to which the optical information recording medium 1 is attached, a spindle motor 82 for rotating the spindle 81, and a spindle motor so as to keep the rotational speed of the optical information recording medium 1 at a predetermined value. And a spindle servo circuit 83 for controlling 82. The optical information recording / reproducing apparatus 10 further records information by irradiating the optical information recording medium 1 with information light and recording reference light, and irradiates the optical information recording medium 1 with reproduction reference light. A pickup 11 for detecting the reproduction light and reproducing the information recorded on the optical information recording medium 1, and a drive device 84 that enables the pickup 11 to move in the radial direction of the optical information recording medium 1. It has.

  The optical information recording / reproducing apparatus 10 further includes a detection circuit 85 for detecting a focus error signal FE, a tracking error signal TE, and a reproduction signal RF from the output signal of the pickup 11, and a focus error signal detected by the detection circuit 85. Based on FE, an actuator in the pickup 11 is driven to move the objective lens in the thickness direction of the optical information recording medium 1 to perform focus servo, and a tracking error signal TE detected by the detection circuit 85. The tracking servo circuit 87 that drives the actuator in the pickup 11 to move the objective lens in the radial direction of the optical information recording medium 1 to perform tracking servo, the tracking error signal TE, and a command from a controller to be described later. Desperate The device 84 and are controlled and a slide servo circuit 88 for performing a slide servo for moving the pickup 11 in the radial direction of the optical information recording medium 1.

  The optical information recording / reproducing apparatus 10 further decodes output data of a CCD array (to be described later) in the pickup 11 to reproduce the data recorded in the data area 7 of the optical information recording medium 1, or from the detection circuit 85. A signal processing circuit 89 that reproduces a basic clock and discriminates an address from the reproduction signal RF, a controller 90 that controls the entire optical information recording / reproducing apparatus 10, and an operation unit that gives various instructions to the controller 91. The controller 90 inputs the basic clock and address information output from the signal processing circuit 89, and controls the pickup 11, spindle servo circuit 83, slide servo circuit 88, and the like. The spindle servo circuit 83 receives the basic clock output from the signal processing circuit 89. The controller 90 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and the CPU executes a program stored in the ROM using the RAM as a work area. Thus, the function of the controller 90 is realized.

  Next, the configuration of the pickup 11 in the present embodiment will be described with reference to FIG. The pickup 11 includes an objective lens 12 that faces the transparent substrate 2 side of the optical information recording medium 1 when the optical information recording medium 1 is fixed to the spindle 81, and the objective lens 12 in the thickness direction of the optical information recording medium 1. In addition, an actuator 13 that is movable in the radial direction, and a two-part optical rotatory plate 14 and a prism block 15 that are sequentially disposed from the objective lens 12 side are provided on the opposite side of the optical information recording medium 1 in the objective lens 12. The two-divided optical rotatory plate 14 includes an optical rotatory plate 14L disposed in the left portion of the optical axis in FIG. 1 and an optical rotatory plate 14R disposed in the right portion of the optical axis in FIG. The optical rotation plate 14L rotates the polarization direction by + 45 °, and the optical rotation plate 14R rotates the polarization direction by −45 °. The prism block 15 has a semi-reflective surface 15a and a reflective surface 15b arranged in order from the two-divided optical rotatory plate 14 side. Both the semi-reflective surface 15a and the reflective surface 15b are arranged in parallel to each other with the normal direction inclined by 45 ° with respect to the optical axis direction of the objective lens 12.

  The pickup 11 further includes a prism block 19 disposed on the side of the prism block 15. The prism block 19 is disposed at a position corresponding to the semi-reflecting surface 15a of the prism block 15, and is disposed at a position corresponding to the reflecting surface 19a parallel to the semi-reflecting surface 15a, the reflecting surface 15b, and the reflecting surface 15b. And a parallel semi-reflective surface 19b.

  The pickup 11 further includes a convex lens 16 and a phase spatial light modulator 17 that are sequentially arranged from the prism block 15 side at positions corresponding to the semi-reflective surface 15a and the reflective surface 19a between the prism block 15 and the prism block 19. And a spatial light modulator 18 disposed between the prism block 15 and the prism block 19 at a position corresponding to the reflecting surface 15b and the semi-reflecting surface 19b.

  The phase spatial light modulator 17 has a large number of pixels arranged in a lattice pattern, and the phase of the light can be spatially modulated by selecting the phase of the emitted light for each pixel. ing. As the phase spatial light modulator 17, a liquid crystal element can be used.

  The spatial light modulator 18 has a large number of pixels arranged in a grid, and spatially modulates light according to light intensity by selecting a light transmission state and a light blocking state for each pixel. Information light carrying information can be generated. As the spatial light modulator 18, a liquid crystal element can be used. The spatial light modulator 18 constitutes information light generating means in the present invention.

  The pickup 11 further has a CCD array as detection means arranged in a direction in which return light from the optical information recording medium 1 is reflected by the semi-reflecting surface 19b of the prism block 19 after passing through the spatial light modulator 18. 20 is provided.

  The pickup 11 further includes a beam splitter 23, a collimator lens 24, and a light source device 25 that are sequentially arranged from the prism block 19 side on the side of the prism block 19 opposite to the spatial light modulator 18. The beam splitter 23 has a semi-reflective surface 23 a whose normal direction is inclined by 45 ° with respect to the optical axis direction of the collimator lens 24. The light source device 25 emits coherent linearly polarized light, and for example, a semiconductor laser can be used.

  The pickup 11 further includes a photodetector 26 arranged in a direction in which light from the light source device 25 is reflected by the semi-reflective surface 23 a of the beam splitter 23, and the beam splitter 23 on the opposite side of the beam splitter 23 from the photodetector 26. A convex lens 27, a cylindrical lens 28, and a four-divided photodetector 29 are provided in this order from the side. The photodetector 26 receives light from the light source device 25, and its output is used to automatically adjust the output of the light source device 25. As shown in FIG. 3, the four-divided photodetector 29 is divided into four light receiving parts divided by a dividing line 30a parallel to the direction corresponding to the track direction in the optical information recording medium 1 and a dividing line 30b orthogonal to the direction. It has parts 29a-29d. The cylindrical lens 28 is arranged so that the central axis of its cylindrical surface forms 45 ° with respect to the dividing lines 30 a and 30 b of the four-divided photodetector 29.

  The phase spatial light modulator 17, the spatial light modulator 18, and the light source device 25 in the pickup 11 are controlled by a controller 90 in FIG. The controller 90 holds information on a plurality of modulation patterns for spatially modulating the phase of light in the phase spatial light modulator 17. The operation unit 91 can select an arbitrary modulation pattern from a plurality of modulation patterns. Then, the controller 90 provides the phase spatial light modulator 17 with the modulation pattern selected by the controller 90 or the information of the modulation pattern selected by the operation unit 91 according to a predetermined condition, and the phase spatial light modulator 17 provides the information from the controller 90. The phase of light is spatially modulated with a corresponding modulation pattern in accordance with information on the modulation pattern to be obtained.

  Further, the reflectance of each of the semi-reflective surfaces 15a and 19b in the pickup 11 is appropriately set so that, for example, the intensity of the information light incident on the optical information recording medium 1 and the recording reference light are equal.

  FIG. 3 is a block diagram showing a configuration of a detection circuit 85 for detecting the focus error signal FE, the tracking error signal TE, and the reproduction signal RF based on the output of the quadrant photodetector 29. The detection circuit 85 adds the outputs of the diagonal light receiving units 29a and 29d of the quadrant photodetector 29 and adds the outputs of the diagonal light receiving units 29b and 29c of the quadrant photodetector 29. Along the track direction of the quadrature detector 29, the subtractor 33 that calculates the difference between the output of the adder 31 and the output of the adder 32, and generates the focus error signal FE by the astigmatism method. An adder 34 for adding the outputs of the adjacent light receiving portions 29a and 29b, an adder 35 for adding the outputs of the adjacent light receiving portions 29c and 29d along the track direction of the quadrant photodetector 29, and an adder 34 The difference between the output and the output of the adder 35 is calculated to generate a tracking error signal TE by the push-pull method. By adding the output of the vessel 35 and an adder 37 which generates a reproduced signal RF. In the present embodiment, the reproduction signal RF is a signal obtained by reproducing information recorded in the address / servo area 6 in the optical information recording medium 1.

  Next, the operation of the optical information recording / reproducing apparatus according to the present embodiment will be described in order for the servo, the recording, and the reproduction. Note that the optical information recording medium 1 is controlled by the spindle motor 82 so as to maintain a specified rotational speed at any time of servo, recording, and reproduction.

  First, referring to FIG. 4, the operation during servo will be described. At the time of servo, all the pixels of the spatial light modulator 18 are set in a transmission state. The output of the emitted light from the light source device 25 is set to a low output for reproduction. The controller 90 predicts the timing at which the light emitted from the objective lens 12 passes through the address / servo area 6 based on the basic clock regenerated from the reproduction signal RF, and the light emitted from the objective lens 12 is address / servo area. While passing through 6, the above setting is made.

  The light emitted from the light source device 25 is converted into a parallel light beam by the collimator lens 24, is incident on the beam splitter 23, and part of the light amount is transmitted through the semi-reflective surface 23a and part of the light is reflected. The light reflected by the semi-reflective surface 23 a is received by the photodetector 26. The light transmitted through the semi-reflective surface 23a enters the prism block 19, and a part of the light amount is transmitted through the semi-reflective surface 19b. The light transmitted through the semi-reflective surface 19b passes through the spatial light modulator 18, is reflected by the reflective surface 15b of the prism block 15, a part of the light quantity is transmitted through the semi-reflective surface 15a, and further passes through the two-divided optical rotatory plate 14. The information recording medium 1 is irradiated so as to pass through, be condensed by the objective lens 12, and converge on the boundary surface between the hologram layer 3 and the protective layer 4 in the optical information recording medium 1. This light is reflected by the reflective film 5 of the optical information recording medium 1, and at this time, is modulated by the emboss pits in the address / servo area 6 and returns to the objective lens 12 side.

  The return light from the optical information recording medium 1 is converted into a parallel light beam by the objective lens 12, passes again through the two-divided optical rotatory plate 14, enters the prism block 15, and a part of the light quantity passes through the semi-reflective surface 15a. . The return light transmitted through the semi-reflective surface 15 a is reflected by the reflective surface 15 a, passes through the spatial light modulator 18, and a part of the light amount passes through the semi-reflective surface 19 b of the prism block 19. The return light transmitted through the semi-reflective surface 19b is incident on the beam splitter 23, a part of the light amount is reflected by the semi-reflective surface 23a, and sequentially passes through the convex lens 27 and the cylindrical lens 28, and then detected by the four-divided photodetector 29. The The detection circuit 85 shown in FIG. 3 generates a focus error signal FE, a tracking error signal TE, and a reproduction signal RF based on the output of the four-divided photodetector 29. Based on these signals, focus servo and The tracking servo is performed, and the basic clock is reproduced and the address is discriminated.

  In the servo setting, the pickup 11 has a normal configuration such as CD (compact disc), DVD (digital video disc or digital versatile disc), HS (hyper storage disc), etc. The configuration is the same as that of the pickup for recording and reproduction on the optical disc. Therefore, the optical information recording / reproducing apparatus 10 in the present embodiment can be configured to be compatible with a normal optical disk apparatus.

  Here, A-polarized light and B-polarized light used in the following description are defined as follows. That is, as shown in FIG. 10, A-polarized light is S-polarized light at −45 ° or P-polarized light is linearly-polarized light whose rotation direction is + 45 °, and B-polarized light is S-polarized light at + 45 ° or P-polarized light at −45 °. Linearly polarized light with the polarization direction rotated. The polarization directions of A-polarized light and B-polarized light are orthogonal to each other. S-polarized light is linearly polarized light whose polarization direction is perpendicular to the incident surface (the paper surface of FIG. 1), and P-polarized light is linearly polarized light whose polarization direction is parallel to the incident surface.

  Next, the operation during recording will be described. FIG. 6 is an explanatory diagram showing the state of the pickup 11 during recording. At the time of recording, the spatial light modulator 18 selects a transmission state (hereinafter also referred to as “on”) and a cutoff state (hereinafter also referred to as “off”) for each pixel in accordance with information to be recorded, and transmits light passing therethrough. Information light is generated by spatial modulation. In this embodiment, 1-bit information is expressed by 2 pixels, and one of the 2 pixels corresponding to 1-bit information is always turned on and the other is turned off.

  The phase spatial light modulator 17 selectively gives a phase difference of 0 (rad) or π (rad) to the passing light according to a predetermined modulation pattern with respect to a predetermined phase for each pixel. By doing so, the phase of the light is spatially modulated to generate the recording reference light in which the phase of the light is spatially modulated. The controller 90 provides the phase spatial light modulator 17 with the modulation pattern selected by the controller 90 or the information of the modulation pattern selected by the operation unit 91 according to a predetermined condition. According to the pattern information, the phase of light passing therethrough is spatially modulated.

  The output of the light emitted from the light source device 25 is pulsed to a high output for recording. The controller 90 predicts the timing at which the emitted light from the objective lens 12 passes through the data area 7 based on the basic clock reproduced from the reproduction signal RF, and the emitted light from the objective lens 12 passes through the data area 7. During the above, the above settings are used. While the emitted light from the objective lens 12 passes through the data area 7, focus servo and tracking servo are not performed, and the objective lens 12 is fixed. In the following description, it is assumed that the light source device 25 emits P-polarized light.

  As shown in FIG. 6, the P-polarized light emitted from the light source device 25 is converted into a parallel light beam by the collimator lens 24, enters the beam splitter 23, and a part of the light amount passes through the semi-reflective surface 23a. The light enters the prism block 19. A part of the light amount of the light incident on the prism block 19 is transmitted through the semi-reflective surface 19b, and a part of the light amount is reflected by the semi-reflective surface 19b. The light transmitted through the semi-reflective surface 19b passes through the spatial light modulator 18 and is spatially modulated according to information to be recorded to become information light. This information light is reflected by the reflecting surface 15 b of the prism block 15, and a part of the light quantity passes through the semi-reflecting surface 15 a and passes through the two-divided optical rotatory plate 14. Here, the light passing through the optical rotatory plate 14L of the two-part optical rotator 14 is rotated by + 45 ° in the polarization direction to become A-polarized light, and the light passing through the optical rotatory plate 14R is rotated by −45 ° in the polarization direction. B-polarized light. The information light that has passed through the two-divided optical rotatory plate 14 is collected by the objective lens 12 and converges on the boundary surface of the hologram layer 3 and the protective layer 4 in the optical information recording medium 1, that is, on the reflective film 5. The optical information recording medium 1 is irradiated.

  On the other hand, the light reflected by the semi-reflective surface 19b of the prism block 19 is reflected by the reflective surface 19a, passes through the phase spatial light modulator 17, and the phase of the light is spatially changed according to a predetermined modulation pattern. To become recording reference light. The recording reference light becomes light that passes through the convex lens 16 and converges. A part of the amount of the recording reference light is reflected by the semi-reflective surface 15 a of the prism block 15 and passes through the two-part optical rotatory plate 14. Here, the light passing through the optical rotatory plate 14L of the two-part optical rotator 14 is rotated by + 45 ° in the polarization direction to become A-polarized light, and the light passing through the optical rotatory plate 14R is rotated by −45 ° in the polarization direction. B-polarized light. The recording reference light that has passed through the two-divided optical rotatory plate 14 is condensed by the objective lens 12 and applied to the optical information recording medium 1, and once has the smallest diameter on the near side of the boundary surface between the hologram layer 3 and the protective layer 4. Then, the light passes through the hologram layer 3 while diverging.

  7 and 8 are explanatory views showing the state of light during recording. In these drawings, the symbol 61 indicates P-polarized light, the symbol 63 indicates A-polarized light, and the symbol 64 indicates B-polarized light.

  As shown in FIG. 7, the information light 51 </ b> L that has passed through the optical rotatory plate 14 </ b> L of the two-divided optical rotatory plate 14 becomes A-polarized light and is irradiated onto the optical information recording medium 1 through the objective lens 12. Passes, converges to have the smallest diameter on the reflective film 5, is reflected by the reflective film 5, and passes through the hologram 3 again. The recording reference light 52L that has passed through the optical rotatory plate 14L of the two-divided optical rotatory plate 14 becomes A-polarized light, which is irradiated onto the information recording medium 1 through the objective lens 12, and the hologram layer 3 and the protective layer 4 After converging to the smallest diameter on the near side from the boundary surface, the light passes through the hologram layer 3 while diverging. In the hologram layer 3, the A-polarized information light 51 </ b> L reflected by the reflective film 5 interferes with the A-polarized recording reference light 52 </ b> L traveling toward the reflective film 5 to form an interference pattern, and the light source device 20. When the output of the emitted light becomes a high output, the interference pattern is recorded in volume in the hologram layer 3.

  Further, as shown in FIG. 8, the information light 51R that has passed through the optical rotatory plate 14R of the two-divided optical rotatory plate 14 becomes B-polarized light, which is irradiated onto the information recording medium 1 through the objective lens 12, and the hologram layer 3 , And converges to have the smallest diameter on the reflective film 5 and is reflected by the reflective film 5 to pass through the hologram 3 again. The recording reference light 52R that has passed through the optical rotatory plate 14R of the two-divided optical rotatory plate 14 becomes B-polarized light, which is irradiated onto the information recording medium 1 through the objective lens 12, and the hologram layer 3 and the protective layer 4 After converging to the smallest diameter on the near side from the boundary surface, the light passes through the hologram layer 3 while diverging. In the hologram layer 3, the B-polarized information light 51 R reflected by the reflective film 5 interferes with the B-polarized recording reference light 52 R traveling toward the reflective film 5 to form an interference pattern, and the light source device 20. When the output of the emitted light becomes a high output, the interference pattern is recorded in volume in the hologram layer 3.

  As shown in FIGS. 7 and 8, in this embodiment, the information light and the recording reference light are holograms so that the optical axis of the information light and the optical axis of the recording reference light are arranged on the same line. The layer 3 is irradiated from the same side.

  In the present embodiment, information is multiplexed at the same location on the hologram layer 3 by phase encoding multiplexing by changing the modulation pattern of the recording reference light at the same location on the hologram layer 3 and performing a recording operation a plurality of times. It is possible to record.

  Thus, in the present embodiment, a reflection type (Lippmann type) hologram is formed in the hologram layer 3. The A-polarized information light 51L and the B-polarized recording reference light 52R do not interfere with each other because the polarization directions are orthogonal, and similarly, the B-polarized information light 51R and the A-polarized recording reference light 52L Because the polarization directions are orthogonal, there is no interference. As described above, in the present embodiment, generation of extra interference fringes can be prevented, and a decrease in SN (signal-to-noise) ratio can be prevented.

  Further, in the present embodiment, as described above, the information light is irradiated so as to converge so as to have the smallest diameter on the boundary surface between the hologram layer 3 and the protective layer 4 in the optical information recording medium 1, and information recording is performed. The light is reflected by the reflective film 5 of the medium 1 and returns to the objective lens 12 side. This return light is incident on the quadrant photodetector 29 in the same manner as in the servo operation. Therefore, in the present embodiment, it is possible to perform focus servo even during recording by using the light incident on the quadrant photodetector 29. The recording reference light converges to become the smallest diameter on the near side of the boundary surface between the hologram layer 3 and the protective layer 4 in the optical information recording medium 1 and becomes divergent light. Even if it is reflected by the film 5 and returns to the objective lens 12, no image is formed on the four-divided photodetector 29.

  In the present embodiment, by moving the convex lens 16 back and forth or changing its magnification, an area (hologram) in which one interference pattern by information light and reference light is recorded in the hologram layer 3 in a volumetric manner. The size can be arbitrarily determined.

  Next, the operation during reproduction will be described with reference to FIG. At the time of reproduction, all the pixels of the spatial light modulator 18 are turned on. Further, the controller 90 gives information on the modulation pattern of the recording reference light at the time of recording the information to be reproduced to the phase spatial light modulator 17, and the phase spatial light modulator 17 gives the modulation pattern given by the controller 90. According to the information, the phase of the light passing therethrough is spatially modulated to generate reproduction reference light in which the phase of the light is spatially modulated.

  The output of the emitted light from the light source device 25 is set to a low output for reproduction. The controller 90 predicts the timing at which the emitted light from the objective lens 12 passes through the data area 7 based on the basic clock reproduced from the reproduction signal RF, and the emitted light from the objective lens 12 passes through the data area 7. During the above, the above settings are used. While the emitted light from the objective lens 12 passes through the data area 7, focus servo and tracking servo are not performed, and the objective lens 12 is fixed.

  As shown in FIG. 9, the P-polarized light emitted from the light source device 25 is converted into a parallel light beam by the collimator lens 24, is incident on the beam splitter 23, and a part of the light amount is transmitted through the semi-reflective surface 23a. The light enters the prism block 19. The light incident on the prism block 19 is partially reflected by the semi-reflective surface 19b, and the reflected light is reflected by the reflective surface 19a and passes through the phase spatial light modulator 17, and at that time, According to a predetermined modulation pattern, the phase of the light is spatially modulated to become reproduction reference light. The reproduction reference light is light that passes through the convex lens 16 and converges. A part of the light amount of the reproduction reference light is reflected by the semi-reflective surface 15 a of the prism block 15 and passes through the two-divided optical rotatory plate 14. Here, the light passing through the optical rotatory plate 14L of the two-part optical rotator 14 is rotated by + 45 ° in the polarization direction to become A-polarized light, and the light passing through the optical rotatory plate 14R is rotated by −45 ° in the polarization direction. B-polarized light. The reproduction reference light that has passed through the two-divided optical rotatory plate 14 is condensed by the objective lens 12 and applied to the optical information recording medium 1, and once has the smallest diameter before the boundary surface between the hologram layer 3 and the protective layer 4. Then, the light passes through the hologram layer 3 while diverging.

  10 and 11 are explanatory diagrams showing the state of light during reproduction. In these drawings, the symbol 61 indicates P-polarized light, the symbol 62 indicates S-polarized light, the symbol 63 indicates A-polarized light, and the symbol 64 indicates B polarization is shown.

  As shown in FIG. 10, the reproduction reference light 53L that has passed through the optical rotatory plate 14L of the two-divided optical rotatory plate 14 becomes A-polarized light, which is irradiated onto the optical information recording medium 1 through the objective lens 12, and the hologram layer 3 converges so as to have the smallest diameter before the boundary surface between the protective layer 4 and the protective layer 4, and then passes through the hologram layer 3 while diverging. As a result, the reproduction light 54L corresponding to the information light 51L at the time of recording is generated from the hologram layer 3. The reproduction light 54L travels toward the objective lens 12, is converted into a parallel light beam by the objective lens 12, passes through the two-divided optical rotator 14 again, and becomes S-polarized light.

  Further, as shown in FIG. 11, the reproduction reference light 53R that has passed through the optical rotatory plate 14R of the two-divided optical rotatory plate 14 becomes B-polarized light, which is irradiated onto the optical information recording medium 1 through the objective lens 12. After converging so as to have the smallest diameter on the near side of the boundary surface between the hologram layer 3 and the protective layer 4, the light passes through the hologram layer 3 while diverging. As a result, the reproduction light 54R corresponding to the information light 51R at the time of recording is generated from the hologram layer 3. The reproduction light 54R travels toward the objective lens 12, is converted into a parallel light beam by the objective lens 12, passes through the two-split optical rotator 14 again, and becomes S-polarized light.

  The reproduction light that has passed through the two-divided optical rotatory plate 14 enters the prism block 15, and a part of the light quantity is transmitted through the semi-reflective surface 15a. The reproduction light transmitted through the semi-reflecting surface 15a is reflected by the reflecting surface 15a, passes through the spatial light modulator 18, and a part of the light amount is reflected by the semi-reflecting surface 19b of the prism block 19 and enters the CCD array 20. Then, it is detected by the CCD array 20. An on / off pattern is formed on the CCD array 20 by the spatial light modulator 18 at the time of recording, and information is reproduced by detecting this pattern.

  When a plurality of pieces of information are recorded in the hologram layer 3 by changing the modulation pattern of the recording reference light, the same modulation pattern as that of the reproduction reference light is recorded. Only information corresponding to the reference light is reproduced.

  As shown in FIGS. 10 and 11, in this embodiment, the reproduction reference light is irradiated and the reproduction light is irradiated so that the optical axis of the reproduction reference light and the optical axis of the reproduction light are arranged on the same line. Collection is performed from the same surface side of the hologram layer 3.

  In the present embodiment, a part of the reproduction light is incident on the four-divided photodetector 29 like the return light at the time of servo. Therefore, in the present embodiment, it is possible to perform focus servo even during reproduction using the light incident on the quadrant photodetector 29. The reproduction reference light converges to become the smallest diameter on the near side of the interface between the hologram layer 3 and the protective layer 4 in the optical information recording medium 1 and becomes divergent light. Even if the light is reflected by the reflective film 5 and returns to the objective lens 12 side, no image is formed on the quadrant photodetector 29.

  When a two-dimensional pattern of reproduction light is detected by the CCD array 20, it is necessary to accurately position the reproduction light and the CCD array 20 or recognize a reference position in the reproduction light pattern from the detection data of the CCD array 20. There is. In the present embodiment, the latter is adopted. Here, a method for recognizing the reference position in the reproduction light pattern from the detection data of the CCD array 20 will be described with reference to FIGS. As shown in FIG. 12A, the aperture in the pickup 11 is divided into two regions 71L and 71R that are symmetrical about the optical axis by the two-divided optical rotatory plate 14. Further, as shown in FIG. 12B, the aperture is divided into a plurality of pixels 72 by the spatial light modulator 18. This pixel 72 is the minimum unit of two-dimensional pattern data. In this embodiment, two pixels represent 1-bit digital data “0” or “1”, and one of the two pixels corresponding to 1-bit information is turned on and the other is turned off. When the two pixels are both on or off, error data is obtained. Thus, expressing 1-bit digital data with two pixels has an advantage that the detection accuracy of data can be increased by differential detection. FIG. 13A represents a set 73 of two pixels corresponding to 1-bit digital data. Hereinafter, an area where the set 73 exists is referred to as a data area. In the present embodiment, reference position information indicating the reference position in the reproduction light pattern is included in the information light by using the fact that error data is obtained when both of the two pixels are on or off. . That is, as shown in FIG. 13B, a cross-shaped region 74 having a width of 2 pixels parallel to the dividing line and a width of 2 pixels perpendicular to the dividing line is formed. The error data is intentionally arranged in a predetermined pattern. Hereinafter, this error data pattern is referred to as a tracking pixel pattern. This tracking pixel pattern becomes reference position information. In FIG. 13B, reference numeral 75 represents an on pixel, and reference numeral 76 represents an off pixel. Further, the area 77 of the four pixels in the central portion is always turned off.

  When the tracking pixel pattern and the pattern corresponding to the data to be recorded are combined, a two-dimensional pattern as shown in FIG. In the present embodiment, among the regions other than the data region, the upper half in the drawing is turned off and the lower half is turned on, and the pixels in the data region that are in contact with the region other than the data region are other than the data region. If the area opposite to the area, that is, the area other than the data area is off, the area is on. This makes it possible to more clearly detect the boundary portion of the data area from the detection data of the CCD array 20.

  At the time of recording, an interference pattern between the information light spatially modulated according to the two-dimensional pattern as shown in FIG. 14A and the recording reference light is recorded on the hologram layer 3. As shown in FIG. 14B, the reproduction light pattern obtained during reproduction has a lower contrast and a lower SN ratio than during recording. At the time of reproduction, the CCD array 20 detects the reproduction light pattern as shown in FIG. 14B and discriminates the data. At this time, the tracking pixel pattern is recognized and the position is used as a reference position for data. Is determined.

  FIG. 15A conceptually shows the contents of data determined from the reproduction light pattern. In the figure, each area marked with a symbol such as A-1-1 represents 1-bit data. In the present embodiment, the data area is divided into four areas 78A, 78B, 78C, and 78D by dividing the data area into a cross-character area 74 in which a tracking pixel pattern is recorded. Then, as shown in FIG. 15B, the diagonal areas 78A and 78C are combined to form a rectangular area, and the diagonal areas 78B and 78D are similarly combined to form a rectangular area. An ECC table is formed by arranging two rectangular areas vertically. The ECC table is a data table formed by adding an error correction code (ECC) such as a CRC (cyclic redundancy check) code to data to be recorded. FIG. 15B shows an example of an ECC table of n rows and m columns, and other arrangements can be freely designed. Further, the data array shown in FIG. 15A uses a part of the ECC table shown in FIG. 15B. Of the ECC table shown in FIG. The portion that is not used in the data array shown in 15 (a) is set to a constant value regardless of the data content. At the time of recording, the ECC table as shown in FIG. 15B is decomposed into four areas 78A, 78B, 78C and 78D and recorded on the optical information recording medium 1 as shown in FIG. In some cases, data having an arrangement as shown in FIG. 15A is detected, rearranged to reproduce an ECC table as shown in FIG. 15B, and error correction is performed based on the ECC table. To play back the data.

  Recognition of the reference position (tracking pixel pattern) and error correction in the reproduction light pattern as described above are performed by the signal processing circuit 89 in FIG.

  As described above, according to the optical information recording / reproducing apparatus 10 of the present embodiment, the optical information recording medium at the time of recording can be recorded on the optical information recording medium 1 while the information can be multiplexed and recorded by phase encoding multiplexing. The recording reference light and the information light are irradiated on the optical information recording medium 1 and the recording reference light is irradiated on the optical information recording medium 1 and the reproduction light is collected on the same axis from the same surface side. As described above, the optical system for recording or reproduction can be made smaller than the conventional holographic recording method, and there is a problem of stray light as in the case of the conventional holographic recording method. Does not occur. Further, according to the present embodiment, the optical system for recording and reproduction can be configured in the form of the pickup 11 similar to a normal optical disk apparatus. Accordingly, random access to the optical information recording medium 1 can be easily performed.

  In addition, according to the present embodiment, information for performing focus servo and tracking servo is recorded on the optical information recording medium 1, and the focus servo and tracking servo can be performed using this information. The positioning of the light for recording or reproduction can be performed with high accuracy. As a result, the removability is good, random access is facilitated, and the recording density, recording capacity, and transfer rate can be increased. In particular, in the recording of the present embodiment, the recording density, the recording capacity, and the transfer rate can be drastically increased in combination with the fact that information can be multiplexed and recorded by phase encoding multiplexing. For example, when a series of information is multiplexed and recorded at the same location on the hologram layer 3 while changing the modulation pattern of the recording reference light, the information can be recorded and reproduced at a very high speed. .

  According to the present embodiment, the information recorded on the optical information recording medium 1 is reproduced unless the reproduction reference light having the same modulation pattern as the modulation pattern of the recording reference light at the time of recording the information is used. Therefore, copy protection and confidentiality can be easily realized. Further, according to the present embodiment, various types of information (for example, various kinds of software) having different reference light modulation patterns are recorded on the optical information recording medium 1, and the optical information recording medium 1 itself is relatively It is possible to realize a service that provides information to the user at a low cost, and provides information on the modulation pattern of the reference light that can reproduce each type of information individually as key information for a fee according to the user's request.

  Further, according to the optical information recording / reproducing apparatus 10 according to the present embodiment, the reference position information indicating the reference position in the reproduction light pattern is included in the information light, so that the reproduction light pattern can be easily recognized. become.

  Further, according to the optical information recording / reproducing apparatus 10 of the present embodiment, the information recorded on the recording medium by the embossed pits is reproduced by setting the pickup 11 to the servo state shown in FIG. Therefore, compatibility with a conventional optical disc apparatus can be provided.

  In addition, according to the optical information recording / reproducing apparatus 10 according to the present embodiment, each piece of information multiplexed and recorded on the optical information recording medium 1 is associated with the modulation pattern of the phase of the different reference light. It is extremely difficult to duplicate the optical information recording medium 1 on which is recorded. Therefore, illegal duplication can be prevented.

  Further, in the optical information recording medium 1 in the present embodiment, the information is recorded because the hologram layer 3 on which information is recorded using holography is separated from the layer on which information such as addresses is recorded by embossed pits. In order to duplicate the optical information recording medium 1 that has been made, these two layers must be made to correspond to each other. In this respect, duplication is difficult and illegal duplication can be prevented.

  Next, an optical information recording / reproducing apparatus according to a second embodiment of the present invention will be described. The present embodiment is an example in which multiplex recording can be performed by using both phase encoding multiplexing and hole burning type wavelength multiplexing. The overall configuration of the optical information recording / reproducing apparatus according to the present embodiment is substantially the same as the configuration of the optical information recording / reproducing apparatus 10 according to the first embodiment shown in FIG.

  First, the hole burning type wavelength multiplexing will be briefly described. Hole burning refers to a phenomenon that causes a change in light absorption at the wavelength position of incident light in a light absorption spectrum, and is also referred to as photochemical hole burning. Hereinafter, a material that causes hole burning, that is, a material that causes a change in light absorption at the wavelength position of incident light in the light absorption spectrum is referred to as a hole burning material. The hole burning material is generally a material in which a light absorption center (called a guest) material such as a pigment is dispersed in a medium (called a host) material having an irregular structure such as an amorphous material. This hole burning material has a broad light absorption spectrum due to superposition of light absorption spectra of a large number of guests at a very low temperature. When such a hole burning material is irradiated with light of a specific wavelength such as a laser beam (however, a wavelength within the light absorption band of the hole burning material), only the guest having a resonance spectrum corresponding to the wavelength is subjected to a photochemical reaction. Therefore, in the light absorption spectrum of the hole burning material, the light absorption rate decreases at the wavelength position of the irradiated light.

  FIG. 16 shows a state in which the light absorptance decreases at a plurality of wavelength positions by irradiation with light of a plurality of wavelengths in the light absorption spectrum of the hole burning material. In the hole burning material, the portion where the light absorptance is reduced by light irradiation is called a hole. Since this hole is extremely small, it becomes possible to multiplex-record a plurality of information on the hole-burning material by changing the wavelength, and this multiplex recording method is called hole-burning type wavelength multiplex. Since the hole has a size of about 10-2 nm, it is considered that a multiplicity of about 103 to 104 can be obtained with the hole burning material. For detailed explanation of hole burning, see, for example, “Corona Inc.“ Basics of Optical Memory ”, pages 104-133, 1990” and the previous document “New Real-Time Recording and Reproduction of Wavelength Multiplexed Hologram Using PHB” Is described in “Studies in”.

  In the present embodiment, a plurality of holograms can be formed by changing the wavelength of the hole burning material by utilizing the above-described hole burning type wavelength multiplexing. Therefore, in the optical information recording medium 1 used in the optical information recording / reproducing apparatus according to the present embodiment, the hologram layer 3 is formed of the above-described hole burning material.

  In the present embodiment, the light source device 25 in the pickup 11 can selectively emit coherent light having a plurality of wavelengths in the light absorption band of the hole burning material forming the hologram layer 3. Examples of such a light source device 25 include a wavelength tunable laser device having a dye laser and a wavelength selection element (prism, diffraction grating, etc.) for selecting the wavelength of the emitted light of the dye laser, and a laser and an emitted light of the laser. A tunable laser device having a wavelength conversion element using a nonlinear optical element for converting the wavelength can be used.

  In the present embodiment, the operation unit 91 can select the modulation pattern of the reference light from a plurality of modulation patterns as well as the first embodiment, and can change the wavelength of the emitted light from the light source device 25. , It is possible to select from a plurality of selectable wavelengths. Then, the controller 90 gives the information on the wavelength selected by the controller 90 or the wavelength selected by the operation unit 91 to the light source device 25 according to a predetermined condition, and the light source device 25 responds according to the wavelength information given from the controller 90. Light of wavelength is emitted.

  The other configuration of the optical information recording / reproducing apparatus in the example is the same as that of the first embodiment.

  In the optical information recording / reproducing apparatus according to the present embodiment, at the time of recording, the wavelength of the light emitted from the light source device 25 is selected from a plurality of selectable wavelengths. Thereby, information light and recording reference light of the selected wavelength are generated. In this embodiment, multiple recording can be performed by hole-burning type wavelength multiplexing by performing a recording operation a plurality of times by changing the wavelengths of the information light and the recording reference light at the same location of the hologram layer 3.

  Further, in the optical information recording / reproducing apparatus according to the present embodiment, the recording operation is performed a plurality of times by changing the modulation pattern of the recording reference light at a certain wavelength at the same location of the hologram layer 3, and further at other wavelengths. Similarly, by performing the recording operation a plurality of times by changing the modulation pattern of the recording reference light, multiplex recording can be performed using both phase encoding multiplexing and hole burning type wavelength multiplexing. In this case, if the multiplicity by phase encoding multiplexing is N and the multiplicity by hole burning type wavelength multiplexing is M, N × M multiplicity is obtained. Therefore, according to the present embodiment, it is possible to further increase the recording density, the recording capacity, and the transfer rate as compared with the first embodiment.

  According to the present embodiment, the information recorded on the optical information recording medium 1 is reproduced unless the reproduction reference light having the same wavelength as the information light and the recording reference light at the time of recording the information is used. Therefore, as in the first embodiment, copy protection and confidentiality can be easily realized. Furthermore, when multiplex recording is performed using both phase-encoding multiplex and hole burning type wavelength multiplex, the same wavelength as that of the information light and the recording reference light at the time of recording the information, and the recording reference Since reproduction cannot be performed unless the reproduction reference light having the same modulation pattern as the light modulation pattern is used, copy protection and confidentiality can be more firmly realized.

  Further, according to the present embodiment, various types of information having different wavelengths of information light and recording reference light or modulation patterns of reference light are recorded on the optical information recording medium 1, and the optical information recording medium 1 is recorded. The service itself is provided to the user at a relatively low cost, and according to the user's request, the information on the wavelength of the reference light and the modulation pattern that can reproduce each type of information is separately provided as key information for a fee. Realization is possible.

  Other operations and effects in the present embodiment are the same as those in the first embodiment.

  Next, an optical information recording / reproducing apparatus according to a third embodiment of the present invention will be described. The overall configuration of the optical information recording / reproducing apparatus according to the present embodiment is substantially the same as the configuration of the optical information recording / reproducing apparatus 10 according to the first embodiment shown in FIG. However, the configuration of the pickup is different from that of the first embodiment.

  FIG. 17 is an explanatory view showing the configuration of the pickup in the present embodiment, and FIG. 18 is a plan view showing the configuration of the optical unit including each element constituting the pickup.

  The pickup 111 in the present embodiment includes a light source device 112 that emits coherent linearly polarized laser light, and a collimator lens 113 that is sequentially arranged from the light source device 112 side in the traveling direction of the light emitted from the light source device 112. , An intermediate density filter (hereinafter referred to as ND filter) 114, an optical element for optical rotation 115, a polarization beam splitter 116, a phase spatial light modulator 117, a beam splitter 118, and a photodetector 119. The light source device 112 emits linearly polarized light of S polarization or P polarization. The collimator lens 113 emits the light emitted from the light source device 112 as a parallel light flux. The ND filter 114 has a characteristic that makes the intensity distribution of the emitted light from the collimator lens 113 uniform. The optical rotatory optical element 115 rotates the light emitted from the ND filter 114 and emits light including an S-polarized component and a P-polarized component. As the optical rotation optical element 115, for example, a half-wave plate or an optical rotation plate is used. The polarization beam splitter 116 has a polarization beam splitter surface 116a that reflects the S-polarized component and transmits the P-polarized component of the light emitted from the optical rotation optical element 115. The phase spatial light modulator 117 is the same as the phase spatial light modulator 17 in the first embodiment. The beam splitter 118 has a beam splitter surface 118a. The beam splitter surface 118a transmits, for example, 20% of the P-polarized component and reflects 80% thereof. The photodetector 119 is used for monitoring the light amount of the reference light and performing automatic light control (hereinafter referred to as APC) of the reference light. In the photodetector 119, the light receiving unit may be divided into a plurality of regions so that the intensity distribution of the reference light can be adjusted.

  The pickup 111 further includes a polarizing beam splitter 120, a two-part optical rotation plate 121, and a polarization beam splitter 120 arranged in order from the beam splitter 118 side in a direction in which light from the light source device 112 is reflected by the beam splitter surface 118 a of the beam splitter 118 and travels. A rising mirror 122 is provided. The polarization beam splitter 120 has a polarization beam splitter surface 120a that reflects the S polarization component and transmits the P polarization component of the incident light. The two-divided optical rotatory plate 121 includes an optical rotatory plate 121R disposed in the right portion of the optical axis in FIG. 17 and an optical rotatory plate 121L disposed in the left portion of the optical axis. The optical rotation plates 121R and 121L are the same as the optical rotation plates 14R and 14L of the two-part optical rotation plate 14 in the first embodiment. The optical rotation plate 121R rotates the polarization direction by −45 °, and the optical rotation plate 121L Rotate direction + 45 °. The rising mirror 122 is tilted by 45 ° with respect to the optical axis of the light from the two-divided optical rotatory plate 121, and reflects the light from the two-divided optical rotatory plate 121 in a direction perpendicular to the paper surface in FIG. It has a reflective surface.

  The pickup 111 is further arranged in a direction in which the light from the two-part optical rotation plate 121 is reflected by the reflecting surface of the rising mirror 122 and travels, and when the optical information recording medium 1 is fixed to the spindle 81, An objective lens 123 facing the transparent substrate 2 side of the information recording medium 1 and an actuator 124 (see FIG. 18) that can move the objective lens 123 in the thickness direction and the track direction of the optical information recording medium 1 are provided. .

  The pickup 111 further includes a spatial light modulator 125 and a convex lens 126 arranged in order from the polarization beam splitter 116 side in the direction in which light from the light source device 112 is reflected by the polarization beam splitter surface 116a of the polarization beam splitter 116 and travels. , A beam splitter 127 and a photodetector 128 are provided. The spatial light modulator 125 is the same as the spatial light modulator 18 in the first embodiment. The convex lens 126 has a function of forming an interference area between the recording reference light and the information light by converging the information light on the near side of the recording reference light in the optical information recording medium 1. Further, by adjusting the position of the convex lens 126, the size of the interference area between the recording reference light and the information light can be adjusted. The beam splitter 127 has a beam splitter surface 127a. The beam splitter surface 127a transmits, for example, 20% of the S-polarized component and reflects 80%. The photodetector 128 is used for monitoring the light quantity of information light and performing APC of information light. In the photodetector 128, the light receiving unit may be divided into a plurality of regions so that the intensity distribution of the information light can be adjusted. Light that enters the beam splitter 127 from the convex lens 126 side and is reflected by the beam splitter surface 127 a enters the polarization beam splitter 120.

  The pickup 111 further includes a convex lens 129, a cylindrical lens 130, and a four-divided photodetector 131 arranged in this order from the beam splitter 127 side on the side opposite to the polarization beam splitter 120 in the beam splitter 127. The 4-split photo detector 131 is the same as the 4-split photo detector 29 in the first embodiment. The cylindrical lens 28 is arranged such that the central axis of its cylindrical surface forms 45 ° with respect to the dividing line of the four-divided photodetector 131.

  The pickup 111 further includes an imaging lens 132 and a CCD array 133 arranged in order from the beam splitter 118 side on the side opposite to the polarization beam splitter 120 in the beam splitter 118.

  The pickup 111 further includes a collimator lens 134 and a fixing light source device 135 arranged in this order from the side of the polarization beam splitter 116 on the side opposite to the spatial light modulator 125 in the polarization beam splitter 116. The fixing light source device 135 emits light for fixing information recorded on the hologram layer 3 of the optical information recording medium 1, for example, ultraviolet light having a wavelength of 266 nm. As such a fixing light source device 135, a laser light source, a light source device that emits light by converting the wavelength of light emitted from the laser light source through a nonlinear optical medium, or the like is used. The collimator lens 134 converts the light emitted from the fixing light source device 135 into a parallel light beam. In this embodiment, the fixing light source device 135 emits S-polarized light.

  As shown in FIG. 18, the optical unit 140 includes an optical unit main body 141. In FIG. 18, only the bottom surface portion of the optical unit main body 141 is shown. The optical unit main body 141 includes the collimator lens 113, the ND filter 114, the optical rotation optical element 115, the polarization beam splitter 116, the phase spatial light modulator 117, the beam splitter 118, the polarization beam splitter 120, the two-part optical rotation plate 121, A rising mirror 122, a spatial light modulator 125, a convex lens 126, a beam splitter 127, a convex lens 129, a cylindrical lens 130, an imaging lens 132, and a collimator lens 134 are attached.

  FIG. 18 shows an example in which a half-wave plate is used as the optical rotatory optical element 115. In this example, the optical unit main body 141 has a motor 142 and an output shaft of the motor 142 for adjusting the ratio of the S-polarized component and the P-polarized component in the light output from the optical rotatory optical element 115. A gear 143 for transmitting the rotation to the optical rotatory optical element 115 is provided.

  FIG. 19 shows an example of an optical rotation optical element 115 using an optical rotation plate. The optical rotatory optical element 115 in this example has two wedge-shaped optical rotatory plates 115a and 115b facing each other. At least one of these optical rotatory plates 115a and 115b is displaced in the direction of the arrow in the figure by a driving device (not shown), and the optical rotatory plates 115a and 115b overlap as shown in FIGS. 19 (a) and 19 (b). The total thickness of the optical rotatory plates 115a and 115b in the portion changes. As a result, the optical rotation angle of the light passing through the optical rotatory plates 115a and 115b changes, and as a result, the ratio of the S-polarized component and the P-polarized component in the outgoing light of the optical element for optical rotation 115 changes. As shown in FIG. 19 (a), when the total thickness of the optical rotation plates 115a and 115b is large, the optical rotation angle becomes large. As shown in FIG. 19 (b), the total optical rotation plates 115a and 115b When the thickness is small, the optical rotation angle becomes small.

The actuator 124 is attached to the upper surface of the optical unit main body 141. The light source device 112 is integrated with a drive circuit 145 that drives the light source device 112, and is attached to the side surface of the unit main body 141 together with the drive circuit 145. The photodetector 119 is integrated with the APC circuit 146, and is attached to the side surface of the unit main body 141 together with the APC circuit 146. The APC circuit 146 amplifies the output of the photo detector 119 and generates a signal APC _ref used for APC of the reference light. The photodetector 128 is integrated with the APC circuit 147 and is attached to the side surface of the unit main body 141 together with the APC circuit 147. The APC circuit 147 amplifies the output of the photo detector 119 and generates a signal APC _obj used for APC of information light. On the side surface of the unit main body 141 in the vicinity of the motor 142, the signals APC _ref and APC _obj from the APC circuits 146 and 147 are compared, and the S-polarized component and the P-polarized component in the outgoing light of the optical rotatory optical element 115 are compared. A drive circuit 148 for driving the motor 142 is attached so that the ratio is optimal.

  The quadrant photodetector 131 is integrated with a detection circuit 85 (see FIG. 2), and is attached to the side surface of the unit main body 141 together with the detection circuit 85. The CCD array 133 is integrated with a signal processing circuit 149 that drives the CCD array 133 and processes an output signal of the CCD array 133, and is attached to the side surface of the unit main body 141 together with the signal processing circuit 149. The fixing light source device 135 is integrated with a driving circuit 150 that drives the fixing light source device 135, and is attached to the side surface of the unit main body 141 together with the driving circuit 150. An input / output port 151 for inputting / outputting various signals between the circuit in the optical unit 140 and the outside of the optical unit 140 is further attached to the side surface of the unit main body 141. For example, an optical fiber flexible cable 152 including an optical fiber that transmits a signal using light is connected to the input / output port 151.

  Although not shown, a drive circuit for driving the phase spatial light modulator 117 and a drive circuit for driving the spatial light modulator 125 are attached to the upper surface of the optical unit main body 141.

  In FIG. 20, the light source device 112 is a laser of three colors of red (hereinafter referred to as R), green (hereinafter referred to as G), and blue (hereinafter referred to as B) as light in a plurality of wavelength ranges. An example of the configuration of the pickup 111 when light can be emitted and the CCD array 133 can detect light of three colors R, G, and B is shown.

  The light source device 112 in the example illustrated in FIG. 20 includes a color synthesis prism 161. The color combining prism 161 includes an R light incident part 162R, a G light incident part 162G, and a B light incident part 162B. Correction filters 163R, 163G, and 163B are provided at the incident portions 162R, 162G, and 162B, respectively. The light source device 112 further emits semiconductor lasers (hereinafter referred to as LDs) 164R, 164G, and 164B that emit R light, G light, and B light, and parallel light beams emitted from the LDs 164R, 164G, and 164B, respectively. And collimator lenses 165R, 165G, and 165B that are incident on the respective incident portions 162R, 162G, and 162B. The R light, G light, and B light emitted from the LDs 164R, 164G, and 164B are incident on the color combining prism 161 through the collimator lenses 165R, 165G, and 165B and the correction filters 163R, 163G, and 163B. So as to be incident on the ND filter 114. In the example shown in FIG. 20, the collimator lens 113 in FIG. 17 is not provided.

  The CCD array 133 in the example illustrated in FIG. 20 includes a color separation prism 171. The color separation prism 171 includes an R light emitting unit 172R, a G light emitting unit 172G, and a B light emitting unit 172B. Correction filters 173R, 173G, and 173B are provided in the emission portions 172R, 172G, and 172B, respectively. The CCD array 133 is further provided with CCDs 174R, 174G, and 174B that are disposed at positions facing the respective emission portions 172R, 172G, and 172B, and pick up an R light image, a G light image, and a B light image. The light from the imaging lens 132 side is decomposed into R light, G light, and B light by the color separation prism 171, and the R light, G light, and B light pass through correction filters 173 R, 173 G, and 173 B, respectively. The light enters the CCDs 174R, 174G, and 174B.

  Next, the slide feed mechanism of the optical unit 140 in the present embodiment will be described with reference to FIGS. FIG. 21 is a plan view showing the slide feed mechanism, FIG. 22 is a partially cutaway side view showing the slide feed mechanism in a stationary state, and FIG. 23 shows the slide feed mechanism when the optical unit is slightly displaced. It is a part notch side view.

  Two slide feed mechanisms are provided for each of the two shafts 181A and 181B arranged in parallel along the moving direction of the optical unit 140 and two for each of the shafts 181A and 181B, and are movable along the respective shafts 181A and 181B. And a linear spring 183 for moving the optical unit 140 along the shafts 181A and 181B. The plate spring 183 elastically connects the bearings 182 and the optical unit 140 to each other.

  The linear motor 184 includes a coil 185 connected to the lower end of the optical unit 140 and two frame-shaped yokes 186A arranged along the moving direction of the optical unit 140 so that a part of the linear motor 184 penetrates the coil 185. 186B, and magnets 187A and 187B fixed to the inner peripheral portions of the yokes 186A and 186B so as to face the coil 185.

  Here, the operation of the slide feed mechanism will be described. When the linear motor 184 is operated, the optical unit 140 is displaced. When this displacement is minute, the bearing 182 is not displaced and the leaf spring 183 between the bearing 182 and the optical unit 140 is deformed as shown in FIG. When the displacement of the optical unit 140 exceeds a predetermined range, the bearing 182 is also displaced following the optical unit 140. According to such a slide feed mechanism, when the displacement of the optical unit 140 is very small, the bearing 182 is not displaced, and therefore wear due to the sliding of the bearing 182 can be prevented. As a result, it is possible to perform tracking servo by driving the optical unit 140 by the linear motor 184 while ensuring the durability and reliability of the slide feed mechanism. The seek is also performed by the slide feed mechanism.

  The actuator 124 includes a cylindrical actuator body 182 that holds the objective lens 123 and is rotatable about an axis 181. Two holes 183 are formed in the actuator body 182 in parallel with the shaft 181. A focusing coil 184 is provided on the outer periphery of the actuator body 182. Further, an in-field access coil (not shown) is provided on a part of the outer periphery of the focusing coil 184. The actuator 124 further includes a magnet 185 inserted through each hole 183 and a magnet (not shown) disposed so as to face the in-field access coil. The objective lens 123 is arranged so that a line connecting the center of the objective lens 123 and the axis 181 faces the track direction when the actuator 124 is stationary.

  Next, a method for positioning (servo) the reference light and the information light with respect to the data area of the optical information recording medium 1 in the present embodiment will be described with reference to FIGS. The actuator 124 in the present embodiment can move the objective lens 123 in the thickness direction and the track direction of the optical information recording medium 1.

  24A to 24C show an operation of moving the objective lens 123 in the track direction of the optical information recording medium 1 by the actuator 124. FIG. The actuator 124 is in the state shown in FIG. The actuator 124 changes from the state shown in (b) to the state shown in (a) or (c) by energizing an in-field access coil (not shown). The operation of moving the objective lens 123 in the track direction of the optical information recording medium 1 in this way is referred to as in-field access in the present embodiment.

  FIG. 25 shows the direction of movement of the objective lens 123 by seeking and the direction of access within the visual field. In FIG. 25, reference numeral 191 represents the movement direction of the objective lens 123 by seeking, and reference numeral 192 represents the movement direction of the objective lens 123 by access within the visual field. Reference numeral 193 represents the locus of the center of the objective lens 123 when the seek movement and the in-field access are used together. In the in-field access, the center of the objective lens 123 can be moved by, for example, about 2 mm.

  In the present embodiment, the reference light and the information light are positioned (servo) with respect to the data area of the optical information recording medium 1 using the in-view access. FIG. 26 is an explanatory diagram for explaining this positioning. In the optical information recording medium 1 according to the present embodiment, as shown in FIG. 26A, the address / servo area 6 has a groove 201 for each track, but the data area 7 has The groove 201 is not formed. Also, the end of the address / servo area 6 is used for clock reproduction and represents a pit indicating which of the two ends of the data area 7 is adjacent (referred to as polarity in the present embodiment). A column 202 is formed.

  In FIG. 26B, reference numeral 203 represents the locus of the center of the objective lens 123 during recording or reproduction. In the present embodiment, when information is multiplexed and recorded in the data area 7 by phase encoding multiplexing, or when information multiplexed and recorded in the data area 7 is reproduced, the center of the objective lens 123 is set in the data area 7. Without stopping, as shown in FIG. 26B, the center of the objective lens 123 reciprocates within a section including the data area 7 and part of the address / servo area 6 on both sides thereof. The center of the objective lens 123 is moved using in-field access. Then, the clock is reproduced using the pit row 202 and the polarity is judged, and the focus servo and tracking servo are performed using the groove 201 in the section 204 in the address / servo area 6. In the section 205 including the data area 7 between the sections 204 and 204, tracking servo is not performed, and the state when the section 204 is passed is maintained. The position of folding in the movement of the center of the objective lens 123 is determined so as to be a fixed position based on the reproduced clock. In addition, the position where information is multiplexed and recorded in the data area 7 is also determined based on the reproduced clock so as to be a fixed position. In FIG. 26 (b), reference numeral 206 represents a gate signal indicating recording or reproduction timing. In this gate signal, the high (H) level represents the recording or reproduction timing. In order to multiplex-record information at a certain location in the data area 7, for example, the output of the light source device 112 may be selectively set to a high output for recording when the gate signal is at a high level. In addition, in order to reproduce information that is multiplexed and recorded at a certain location in the data area 7, for example, light can be selectively emitted from the light source device 112 when the gate signal is at a high level, or a CCD array. When 133 has an electronic shutter function, an image may be captured using the electronic shutter function when the gate signal is at a high level.

  By positioning the reference light and the information light by the above-described method, the recording / reproducing position is shifted even when recording / reproducing is performed for a relatively long time at the same portion of the optical information recording medium 1. This can be prevented. Further, even if the optical information recording medium 1 is rotating, recording is performed in the same situation as when the optical information recording medium 1 is stationary by performing in-view access so as to follow the rotation of the optical information recording medium 1. Thus, recording and reproduction can be performed for a relatively long time at the same location of the optical information recording medium 1. Further, if the technique for positioning the reference light and the information light by using the in-view access as described above is used, the optical information recording medium is not limited to the disk-shaped optical information recording medium 1 but other forms such as a card shape. In the case of using the reference light, it is possible to easily position the reference light and the information light.

  FIG. 27 shows an example of the locus of the center of the objective lens 123 when a plurality of locations on the optical information recording medium 1 are accessed by using both movement by seek and access within the visual field. In this figure, the vertical straight line represents seek, the horizontal straight line represents movement to other locations in the track direction, and the portion reciprocating within a short section is recorded or reproduced. It represents the part.

  Next, an example of a cartridge that stores the optical information recording medium 1 will be described with reference to FIGS. FIG. 28 is a plan view of the cartridge, and FIG. 29 is a plan view of the cartridge with the shutter opened. The cartridge 211 in this example has a window portion 212 that exposes a part of the optical information recording medium 1 accommodated therein, and a shutter 213 that opens and closes the window portion 212. The shutter 213 is biased in a direction to close the window 212. Normally, as shown in FIG. 28, the window 212 is closed, but when the cartridge 211 is mounted on the optical information recording / reproducing apparatus. The optical information recording / reproducing apparatus is moved in the direction to open the window 212 as shown in FIG.

  Next, an example of the arrangement of the optical unit 140 in the case where a plurality of pickups 111 are provided in one optical information recording / reproducing apparatus will be described with reference to FIGS.

  FIG. 30 shows an example in which two optical units 140 </ b> A and 140 </ b> B are arranged so as to face one side of the optical information recording medium 1. The optical unit 140A has the same form (hereinafter referred to as A type) as the optical unit 140 shown in FIG. On the other hand, the optical unit 140B has a form (hereinafter referred to as B type) that is plane-symmetric with respect to the optical unit 140 shown in FIG. The two optical units 140 </ b> A and 140 </ b> B are arranged at positions facing the optical information recording medium 1 exposed from the window 212 of the cartridge 211. The slide feed mechanisms of the optical units 140A and 140B are arranged so that the centers of the objective lenses 123 of the optical units 140A and 140B move along a line passing through the center of the optical information recording medium 1, respectively. The

  FIG. 31 shows an example in which two optical units are arranged so as to face each surface of the optical information recording medium 1, and a total of four optical units are provided. 32 is a cross-sectional view taken along the line AA ′ of FIG. 31, and FIG. 33 is a cross-sectional view taken along the line BB ′ of FIG. In this example, two optical units 140A and 140B are arranged so as to face one surface (back surface in FIG. 31) of the optical information recording medium 1, and the other surface (surface in FIG. 31) of the optical information recording medium 1 is disposed. Two optical units 140C and 140D are arranged so as to face each other. The optical unit 140C is of the A type, and the optical unit 140D is of the B type.

  The arrangement of the optical units 140A and 140B and their slide feed mechanisms and the conditions for the arrangement of the optical units 140C and 140D and their slide feed mechanisms are as described with reference to FIG. In order to effectively use the four optical units 140A, 140B, 140C, and 140D, it is necessary to use an optical information recording medium 1 that can record and reproduce information from both sides.

FIG. 34 shows an example in which eight optical units are arranged so as to face each surface of the optical information recording medium 1, and a total of 16 optical units are provided. In this example, eight optical units 140 _{1 to} 140 ₈ are arranged so as to face one surface (surface in FIG. 34) of the optical information recording medium 1, and the other surface (FIG. Eight optical units 140 _{9 to} 140 ₁₆ are arranged so as to oppose the rear surface of 34. The optical units 140 ₁ , 140 ₃ , 140 ₅ , 140 ₇ , 140 ₁₀ , 140 ₁₂ , 140 ₁₄ , 140 ₁₆ are of the A type. The optical units 140 ₂ , 140 ₄ , 140 ₆ , 140 ₈ , 140 ₉ , 140 ₁₁ , 140 ₁₃ and 140 ₁₅ are of the B type. The slide feed mechanism of each optical unit is arranged so that the center of the objective lens 123 of each optical unit moves along a line passing through the center of the optical information recording medium 1. In order to effectively use the 16 optical units, it is necessary to use the optical information recording medium 1 that is not housed in the cartridge and can record and reproduce information from both sides.

  By the way, in the system including the optical information recording / reproducing apparatus and the optical information recording medium 1 according to the present embodiment, it is possible to record an extremely large amount of information on the optical information recording medium 1. It is suitable for applications that record a huge amount of continuous information. However, in a system used for such a purpose, if information cannot be reproduced while a large amount of continuous information is recorded, the system becomes very difficult to use.

  Therefore, for example, as shown in FIGS. 30 to 34, by providing a plurality of pickups 111 in one optical information recording / reproducing apparatus, information recording and reproduction are simultaneously performed using one optical information recording medium 1. In addition, recording and reproduction can be performed simultaneously by a plurality of pickups 111, and the performance of recording and reproduction can be improved. In particular, a system that is easy to use can be configured even for applications that record a large amount of continuous information. Can do. In addition, by providing a plurality of pickups 111 in one optical information recording / reproducing apparatus, when searching for desired information from a large amount of information, the performance is greatly improved compared to the case where only one pickup 111 is provided. Can be improved.

  Next, an example of a specific structure of the optical information recording medium 1 in the present embodiment will be described with reference to FIGS.

  The optical information recording medium 1 according to the present embodiment includes a first information layer (hologram layer) on which information is recorded by holography, and second information on which servo information and address information are recorded by embossed pits or the like. With layers. Then, while converging the reference light so as to have the smallest diameter in the second information layer, it is necessary to form an interference region between the recording reference light and the information light in a certain size in the first information layer. Therefore, in this embodiment, a gap (gap) having a certain size is formed between the first information layer and the second information layer. As a result, the reference light is converged so as to have the smallest diameter in the second information layer, and the information recorded in the second information layer can be reproduced, while the reference light and information for recording are recorded in the first information layer. It is possible to form a light interference region with a sufficient size. The optical information recording medium 1 in the present embodiment can be divided into an air gap type and a transparent substrate gap type depending on the gap forming method.

  35 to 37 show the air gap type optical information recording medium 1, FIG. 35 is a sectional view of half of the optical information recording medium 1, and FIG. 36 is an exploded perspective view of half of the optical information recording medium 1. FIG. 37 is a perspective view of a half of the optical information recording medium 1. The optical information recording medium 1 includes a reflective substrate 221 having one surface as a reflective surface, a transparent substrate 222 disposed so as to face the reflective surface of the reflective substrate 221, and the reflective substrate 221 and the transparent substrate 222. The outer peripheral spacers 223 and the inner peripheral spacers 224 are spaced apart from each other by a predetermined interval, and the hologram layer 225 bonded to the surface of the transparent substrate 222 on the reflective substrate 221 side. An air gap having a predetermined thickness is formed between the reflective surface of the reflective substrate 221 and the hologram layer 225. The hologram layer 225 becomes the first information layer. A pregroove is formed on the reflection surface of the reflection substrate 221, and this reflection surface becomes the second information layer.

  38 to 40 show the optical information recording medium 1 of the transparent substrate gap type, FIG. 38 is a sectional view of half of the optical information recording medium 1, and FIG. 39 is an exploded perspective view of half of the optical information recording medium 1. FIG. 40 is a half perspective view of the optical information recording medium 1. The optical information recording medium 1 is configured by laminating a transparent substrate 231, a hologram layer 232 serving as a first information layer, and a transparent substrate 233 in this order. On the surface of the transparent substrate 231 opposite to the hologram layer 232, a pre-groove is formed and a reflective film 234 is provided. A surface of the transparent substrate 231 opposite to the hologram layer 232 is a second information layer. A gap having a predetermined thickness is formed by the transparent substrate 231 between the second information layer and the hologram layer 232. The transparent substrate 233 is thinner than the transparent substrate 231.

  The optical information recording medium 1 in the present embodiment can be divided into a single-sided type and a double-sided type.

  41 to 43 show the single-sided type optical information recording medium 1, FIG. 41 is a sectional view of the optical information recording medium 1 having a thickness of 1.2 mm, and FIG. 42 is a type having a thickness of 0.6 mm. FIG. 43 is an explanatory view showing a method of irradiating the recording reference light and the information light to the single-sided optical information recording medium 1. The optical information recording medium 1 shown in FIGS. 41 and 42 has the structure shown in FIG. However, in the optical information recording medium 1 shown in FIG. 41, the total thickness of the transparent substrate 231, the hologram layer 232, and the transparent substrate 233 is 1.2 mm, and the optical information recording medium 1 shown in FIG. The total thickness of the transparent substrate 231, the hologram layer 232, and the transparent substrate 233 is 0.6 mm.

  The recording reference light 241 irradiated from the objective lens 123 to the optical information recording medium 1 converges to have the smallest diameter on the surface on which the pregroove is formed, and is irradiated from the objective lens 123 to the optical information recording medium 1. The information light 242 converges so as to have the smallest diameter on the near side of the hologram layer 232. As a result, in the hologram layer 232, an interference region 243 is formed by the recording reference light 241 and the information light 242.

  41 and 42 show the transparent substrate gap type single-sided optical information recording medium 1, but the air gap type single-sided optical information recording medium 1 may be configured. In this case, the total thickness of the transparent substrate 222, the hologram layer 225, and the air gap is set to 1.2 mm or 0.6 mm.

  44 to 46 show the double-sided type optical information recording medium 1, FIG. 44 is a cross-sectional view of the transparent substrate gap type optical information recording medium 1, and FIG. 45 shows the air gap type optical information recording medium 1. FIG. 46 is a cross-sectional view and FIG. 46 is an explanatory diagram showing how the reference light for recording and the information light are irradiated to the double-sided type optical information recording medium 1. The optical information recording medium 1 shown in FIG. 44 has a structure in which two single-sided optical information recording media shown in FIG. Further, the optical information recording medium 1 shown in FIG. 45 has a structure in which two single-sided optical information recording media shown in FIG. In the optical information recording medium 1 shown in FIG. 45, the total thickness of the transparent substrate 222 on one side, the hologram layer 225, and the air gap is 0.6 mm.

  The recording reference light 241 irradiated from the objective lens 123 to the optical information recording medium 1 converges to have the smallest diameter on the surface on which the pregroove is formed, and is irradiated from the objective lens 123 to the optical information recording medium 1. The information light 242 converges so as to have the smallest diameter on the near side of the hologram layers 232 and 225. As a result, in the hologram layers 232 and 225, an interference region 243 is formed by the recording reference light 241 and the information light 242.

  By the way, the optical information recording / reproducing apparatus in the present embodiment can record and reproduce information using a conventional optical disc. For example, as shown in FIG. 47, when using a single-sided optical disc 251 in which a pre-groove is formed on one side of the transparent substrate 252 and a reflective film 253 is provided, as shown in FIG. The light irradiated from the objective lens 123 onto the optical disk 251 is converged so that the surface of the optical disk 251 where the pregroove is formed, that is, the information layer has the smallest diameter. In the optical disk 251 shown in FIG. 47, the thickness of the transparent substrate 252 is, for example, 1.2 mm. As an optical disk having the structure as shown in FIG. 47, there are a CD, a CD-ROM, a CD-R (write once type CD), an MD (mini disk), and the like.

  Further, as shown in FIG. 49, a double-sided type optical disk 261 having a structure in which two transparent substrates 262 each having a pre-groove formed on one side and provided with a reflective film 263 are bonded together by the reflective films 263 is used. In this case, as shown in FIG. 50, the light applied to the optical disk 261 from the objective lens 123 is converged so that the surface of the optical disk 261 on which the pregroove is formed, that is, the information layer has the smallest diameter. In the optical disk 261 shown in FIG. 49, the thickness of the transparent substrate 262 on one side is, for example, 0.6 mm. As an optical disk having the structure as shown in FIG. 50, there are a DVD, a DVD-ROM, a DVD-RAM, an MO (magneto-optical) disk, and the like.

  In the optical information recording medium 1 in the present embodiment, the second information layer is the same as the information layer in the conventional optical disc as shown in FIGS. 47 and 49, including the contents of the information to be recorded. It can be made the form. In this case, the information recorded in the second information layer can be reproduced by setting the pickup 111 to the servo state. In addition, since information for servo and address information are also recorded in the information layer of the conventional optical disc, the second information layer is formed in the same form as the information layer of the conventional optical disc. The servo information and address information recorded in the information layer can be used as they are for positioning the information light for recording and reproduction, the recording reference light and the reproduction reference light in the hologram layer. It becomes. In addition, the directory information and directory management information of the information recorded in the first information layer (hologram layer) is recorded in the second information layer (information layer in the conventional optical disc), thereby enabling high-speed search. The application range of the second information layer is wide.

  Next, before describing the operation of the optical information recording / reproducing apparatus according to the present embodiment, the principle of phase encoding multiplexing will be described with reference to FIGS. FIG. 51 is a perspective view showing a schematic configuration of a general recording / reproducing system that performs phase encoding multiplexing. This recording / reproducing system condenses the spatial light modulator 301 for generating information light 302 based on the two-dimensional digital pattern information, and the information light 302 from the spatial light modulator 301, and applies it to the hologram recording medium 300. An irradiating lens 303 and a reference spatial light modulator 304 that generates a reference light 305 whose phase is spatially modulated and irradiates the reference light 305 to the hologram recording medium 300 from a direction substantially orthogonal to the information light 302. And a CCD array 308 for detecting the reproduced two-dimensional digital pattern information, and a lens 307 for condensing the reproduction light 306 emitted from the hologram recording medium 300 and irradiating it on the CCD array 308. .

  In the recording / reproducing system shown in FIG. 51, at the time of recording, information such as an original image to be recorded is digitized, and the 0 or 1 signal is further arranged in two dimensions to obtain two-dimensional digital pattern information (hereinafter referred to as page data and Say). Here, it is assumed that page data # 1 to #n are multiplexed and recorded on the same hologram recording medium 300. Also, two-dimensional digital pattern information for phase modulation (hereinafter referred to as phase data) # 1 to #n that differs for each page data # 1 to #n is generated. First, when recording page data # 1, spatially modulated information light 302 is generated by the spatial light modulator 301 based on the page data # 1, and irradiated to the hologram recording medium 300 via the lens 303. . At the same time, based on the phase data # 1, the phase spatial light modulator 304 generates reference light 305 whose phase is spatially modulated, and irradiates the hologram recording medium 300. As a result, on the hologram recording medium 300, interference fringes formed by superimposing the information light 302 and the reference light 305 are recorded. Similarly, when recording page data # 2 to #n, spatially modulated information light 302 is generated by the spatial light modulator 301 based on the page data # 2 to #n, respectively, and the phase Based on the data # 2 to #n, the phase spatial light modulator 304 generates the reference light 305 whose phase is spatially modulated, and the hologram recording medium 300 is irradiated with the information light 302 and the reference light 305. In this way, a plurality of pieces of information are multiplexed and recorded at the same location on the hologram recording medium 300. A hologram in which information is multiplexed and recorded is called a stack. In the example shown in FIG. 51, the hologram recording medium 300 has a plurality of stacks (stack 1, stack 2,..., Stack m,...).

  In order to reproduce arbitrary page data from the stack, the stack may be irradiated with reference light 305 whose phase is spatially modulated based on the same phase data as when the page data was recorded. Then, the reference light 305 is selectively diffracted by the interference fringes corresponding to the phase data and page data, and the reproduction light 306 is generated. The reproduction light 306 enters the CCD array 308 through the lens 307, and a two-dimensional pattern of the reproduction light is detected by the CCD array 308. Then, the information such as the original image is reproduced by decoding the detected two-dimensional pattern of the reproduction light in reverse to the recording.

FIG. 52 shows how interference fringes are formed on the hologram recording medium 300 due to the interference between the information beam 302 and the reference beam 305. In FIG. 52, (a) includes an information light 302 ₁ based on the page data # 1, by the interference of the reference light 305 ₁ based on the phase data # 1, shows how the interference fringes 309 ₁ is formed. Similarly, (b) includes an information light 302 ₂ based on the page data # 2, by the interference of the reference light 305 ₂ based on the phase data # 2, shows how the interference fringes 309 ₂ is formed, (c) is , the information light 302 ₃ based on the page data # 3, by the interference of the reference light 305 ₃ based on the phase data # 3, shows how the interference fringes 309 ₃ is formed.

  Next, the operation of the optical information recording / reproducing apparatus according to the present embodiment will be described in order for the servo, the recording, and the reproduction.

  First, with reference to FIGS. 53 and 54, the operation during servo will be described. FIG. 53 is an explanatory diagram showing the state of the pickup 111 during servo. At the time of servo, the spatial light modulator 125 is in a state where all pixels are cut off. The phase spatial light modulator 117 is set so that all light passing through each pixel has the same phase. The output of the light emitted from the light source device 112 is set to a low output for reproduction. The controller 90 predicts the timing at which the emitted light from the objective lens 123 passes through the address / servo area 6 based on the basic clock reproduced from the reproduction signal RF, and the emitted light from the objective lens 123 is used as the address / servo area. While passing through 6, the above setting is made.

  The light emitted from the light source device 112 is converted into a parallel light beam by the collimator lens 113, passes through the ND filter 114 and the optical rotation optical element 115 in order, and enters the polarization beam splitter 116. The S-polarized component of the light incident on the polarization beam splitter 116 is reflected by the polarization beam splitter surface 116 a and blocked by the spatial light modulator 125. The P-polarized component of the light incident on the polarization beam splitter 116 passes through the polarization beam splitter surface 116 a, passes through the phase spatial light modulator 117, and enters the beam splitter 118. A part of the light incident on the beam splitter 118 is reflected by the beam splitter surface 118a, passes through the polarization beam splitter 120, and enters the two-divided optical rotation plate 121. Here, light that has passed through the optical rotatory plate 121R of the two-part optical rotatory plate 121 becomes B-polarized light, and light that has passed through the optical rotatory plate 121L becomes A-polarized light. The light that has passed through the two-part optical rotatory plate 121 is reflected by the rising mirror 122, collected by the objective lens 123, and converged on the pre-groove on the back side of the hologram layer in the optical information recording medium 1. Then, the information recording medium 1 is irradiated. This light is reflected on the pregroove, and at that time, is modulated by the pits formed on the pregroove and returns to the objective lens 123 side. In FIG. 53, the rising mirror 122 is omitted.

  The return light from the information recording medium 1 is converted into a parallel light beam by the objective lens 123 and passes through the two-part optical rotatory plate 121 to become S-polarized light. The return light is reflected by the polarization beam splitter surface 120a of the polarization beam splitter 120, enters the beam splitter 127, partially passes through the beam splitter surface 127a, and sequentially passes through the convex lens 129 and the cylindrical lens 130. Detected by a four-divided photodetector 131. The detection circuit 85 generates a focus error signal FE, a tracking error signal TE, and a reproduction signal RF based on the output of the quadrant photodetector 131, and focus servo and tracking servo are performed based on these signals. At the same time, the reproduction of the basic clock and the determination of the address are performed.

Further, part of the light incident on the beam splitter 118 enters the photodetector 119, and a signal APC _ref is generated by the APC circuit 146 based on the output signal of the photodetector 119. Then, APC is performed based on the signal APC _ref so that the amount of light applied to the optical information recording medium 1 is constant. Specifically, the drive circuit 148 drives the motor 142 to adjust the optical rotation optical element 115 so that the signal APC _ref becomes equal to a predetermined value. Alternatively, during servo operation, the optical rotation optical element 115 may be set so that the light passing through the optical rotation optical element 115 becomes only the P-polarized component, and the output of the light source device 112 may be adjusted to perform APC. . When the light receiving unit of the photodetector 119 is divided into a plurality of regions and the phase spatial light modulator 117 can also adjust the amount of transmitted light, the phase is determined based on the output signal for each light receiving unit of the photodetector 119. The transmitted light amount for each pixel in the spatial light modulator 117 may be adjusted so that the intensity distribution of the light irradiated on the optical information recording medium 1 is uniform.

  In the servo setting, the configuration of the pickup 111 is the same as that of a recording / reproducing pickup for an ordinary optical disc. Therefore, the optical information recording / reproducing apparatus in the present embodiment can perform recording and reproduction using a normal optical disk.

  FIG. 54 is an explanatory diagram showing the state of light in the vicinity of the optical disc when recording and reproduction are performed using a normal optical disc by the optical information recording / reproducing apparatus according to the present embodiment. In this figure, a double-sided type optical disk 261 is given as an example of a normal optical disk. In this optical disc 261, a pre-groove 265 is formed on the surface of the transparent substrate 262 on the reflective film 263 side, and light from the objective lens 123 side is applied to the optical disc 261 so as to converge on the pre-groove 265, It is modulated by the pits formed on the pregroove 265 and returns to the objective lens 123 side.

  Next, the operation during recording will be described with reference to FIGS. FIG. 55 is an explanatory view showing the state of the pickup 111 during recording, and FIGS. 56 and 57 are explanatory views showing the state of light in the vicinity of the optical information recording medium 1 during recording. In the following description, as shown in FIG. 56, the optical information recording medium 1 will be described as an example using an air gap type.

  At the time of recording, the spatial light modulator 125 selects a transmission state (hereinafter also referred to as “on”) and a cutoff state (hereinafter also referred to as “off”) for each pixel in accordance with information to be recorded, and transmits light passing therethrough. Information light is generated by spatial modulation. The phase spatial light modulator 117 selectively gives a phase difference of 0 (rad) or π (rad) to each pixel according to a predetermined modulation pattern with reference to a predetermined phase. Thus, the phase of the light is spatially modulated to generate recording reference light in which the phase of the light is spatially modulated.

  In the present embodiment, as already described, when information is multiplexed and recorded in the data area 7 by phase encoding multiplexing, the center of the objective lens 123 is one of the data area 7 and the address / servo area 6 on both sides thereof. The center of the objective lens 123 is moved using in-field access so as to reciprocate within a section including the part. When the center of the objective lens 123 comes to a predetermined position in the data area 7, the output of the light source device 112 is selectively set to a high output for recording.

  The light emitted from the light source device 112 is converted into a parallel light beam by the collimator lens 113, passes through the ND filter 114 and the optical rotation optical element 115 in order, and enters the polarization beam splitter 116. The P-polarized component of the light incident on the polarization beam splitter 116 passes through the polarization beam splitter surface 116a and passes through the phase spatial light modulator 117. At this time, the phase of the light is spatially modulated, and recording is performed. Reference light for This recording reference light is incident on the beam splitter 118. Part of the recording reference light that has entered the beam splitter 118 is reflected by the beam splitter surface 118 a, passes through the polarization beam splitter 120, and enters the two-split optical rotation plate 121. Here, the recording reference light that has passed through the optical rotation plate 121R of the two-part optical rotation plate 121 becomes B-polarized light, and the recording reference light that has passed through the optical rotation plate 121L becomes A-polarized light. The recording reference light that has passed through the two-divided optical rotatory plate 121 is reflected by the rising mirror 122, collected by the objective lens 123, and converged behind the hologram layer 225 in the optical information recording medium 1. The optical information recording medium 1 is irradiated. In FIG. 55, the rising mirror 122 is omitted.

  On the other hand, the S-polarized component of the light incident on the polarization beam splitter 116 is reflected by the polarization beam splitter surface 116a, passes through the spatial light modulator 125, and is spatially modulated according to the information to be recorded. It becomes information light. This information light is incident on the beam splitter 127. A part of the information light incident on the beam splitter 127 is reflected by the beam splitter surface 127 a, reflected by the beam splitter surface 120 a of the polarizing beam splitter 120, and incident on the two-split optical rotation plate 121. Here, the information light that has passed through the optical rotatory plate 121R of the two-part optical rotatory plate 121 becomes A-polarized light, and the information light that has passed through the optical rotatory plate 121L becomes B-polarized light. The information light that has passed through the two-divided optical rotatory plate 121 is reflected by the rising mirror 122, collected by the objective lens 123, and once converged and diffused before the hologram layer 225 in the optical information recording medium 1. The optical information recording medium 1 is irradiated so as to pass through the hologram layer 225.

  As a result, as shown in FIG. 56, in the hologram layer 225, an interference region 313 is formed by the recording reference light 311 and the information light 312. The interference region 313 has a barrel shape. As shown in FIG. 55, the convergence position of the information light can be adjusted by adjusting the position 310 of the convex lens 126, and thereby the size of the interference region 313 can be adjusted.

  As shown in FIG. 57, in the hologram layer 225, the A-polarized recording reference light 311A that has passed through the optical rotatory plate 121L of the two-split optical rotator 121 and the A-polarized light that has passed through the optical rotator 121R of the two-split optical rotator 121 The B-polarized recording reference light 311B that has passed through the optical rotatory plate 121R of the two-split optical rotator 121 and the B-polarized information light 312B that has passed through the optical rotator 121L of the two-split optical rotator 121 Interfere, and these interference patterns are recorded in volume in the hologram layer 225.

  Also, by changing the phase modulation pattern of the recording reference light for each information to be recorded, a plurality of information can be multiplexed and recorded at the same location of the hologram layer 225.

Incidentally, as shown in FIG. 55, a part of the recording reference light incident on the beam splitter 118 is incident on the photodetector 119, and a signal APC _ref is generated by the APC circuit 146 based on the output signal of the photodetector 119. Is done. Further, part of the information light incident on the beam splitter 127 is incident on the photodetector 128, and a signal APC _obj is generated by the APC circuit 147 based on the output signal of the photodetector 128. Based on these signals APC _ref and APC _obj , APC is performed so that the ratio of the intensity of the recording reference light and the information light irradiated onto the optical information recording medium 1 becomes an optimum value. Specifically, the drive circuit 148 compares the signals APC _ref and APC _obj and drives the motor 142 so as to adjust the optical rotation optical element 115 so that they have a desired ratio. When the light receiving unit of the photodetector 119 is divided into a plurality of regions and the phase spatial light modulator 117 can also adjust the amount of transmitted light, the phase is determined based on the output signal for each light receiving unit of the photodetector 119. The transmitted light amount for each pixel in the spatial light modulator 117 may be adjusted so that the intensity distribution of the recording reference light irradiated on the optical information recording medium 1 is uniform. Similarly, when the light receiving unit of the photodetector 128 is divided into a plurality of regions and the spatial light modulator 125 can also adjust the amount of transmitted light, it is based on the output signal for each light receiving unit of the photodetector 128. Alternatively, the amount of transmitted light for each pixel in the spatial light modulator 125 may be adjusted so that the intensity distribution of the information light applied to the optical information recording medium 1 is uniform.

In the present embodiment, APC is performed based on the sum of the signals APC _ref and APC _obj so that the total intensity of the recording reference light and the information light becomes an optimum value. As a method of controlling the total intensity of the recording reference light and the information light, control of the peak value of the output of the light source device 112, the emission pulse width when light is emitted in a pulsed manner, and the intensity of the emitted light over time For example, profile control.

  Next, with reference to FIGS. 58 and 59, the operation at the time of fixing will be described. 58 is an explanatory diagram showing the state of the pickup 111 at the time of fixing, and FIG. 59 is an explanatory diagram showing the state of light in the vicinity of the optical information recording medium 1 at the time of fixing. At the time of fixing, all pixels of the spatial light modulator 125 are blocked. The phase spatial light modulator 117 is set so that all light passing through each pixel has the same phase. No light is emitted from the light source device 112, and S-polarized ultraviolet light for fixing is emitted from the fixing light source device 135.

  The light emitted from the fixing light source device 135 is converted into a parallel light beam by the collimator lens 134, enters the polarization beam splitter 116, is reflected by the polarization beam splitter surface 116 a, passes through the phase spatial light modulator 117, The light enters the splitter 118. A part of the light incident on the beam splitter 118 is reflected by the beam splitter surface 118a, passes through the polarization beam splitter 120, and enters the two-divided optical rotation plate 121. Here, light that has passed through the optical rotatory plate 121R of the two-part optical rotatory plate 121 becomes B-polarized light, and light that has passed through the optical rotatory plate 121L becomes A-polarized light. The light that has passed through the two-divided optical rotatory plate 121 is reflected by the rising mirror 122, collected by the objective lens 123, and converged on the pregroove on the back side of the hologram layer 225 in the optical information recording medium 1. Thus, the information recording medium 1 is irradiated. Then, the interference pattern formed in the interference region 313 in the hologram layer 225 is fixed by this light. In FIG. 58, the rising mirror 122 is omitted.

  The positioning (servo) of the fixing light with respect to the optical information recording medium 1 can be performed in the same manner as the positioning of the recording reference light and the information light during recording.

Further, part of the fixing light incident on the beam splitter 118 enters the photodetector 119, and a signal APC _ref is generated by the APC circuit 146 based on the output signal of the photodetector 119. Then, APC is performed based on the signal APC _ref so that the amount of fixing light applied to the optical information recording medium 1 is constant. Specifically, the output of the fixing light source device 135 is adjusted so that the signal APC _ref becomes equal to a predetermined value. When the light receiving unit of the photodetector 119 is divided into a plurality of regions and the phase spatial light modulator 117 can also adjust the amount of transmitted light, the phase is determined based on the output signal for each light receiving unit of the photodetector 119. The amount of transmitted light for each pixel in the spatial light modulator 117 may be adjusted so that the intensity distribution of the fixing light irradiated on the optical information recording medium 1 is uniform.

  Next, the operation during reproduction will be described with reference to FIGS. FIG. 60 is an explanatory view showing the state of the pickup 111 during reproduction, and FIGS. 61 and 62 are explanatory views showing the state of light in the vicinity of the optical information recording medium 1 during reproduction.

  At the time of reproduction, all the pixels of the spatial light modulator 125 are blocked. The phase spatial light modulator 117 selectively gives a phase difference of 0 (rad) or π (rad) to each pixel according to a predetermined modulation pattern with reference to a predetermined phase. Thus, the phase of the light is spatially modulated to generate reproduction reference light in which the phase of the light is spatially modulated. Here, in the present embodiment, the phase modulation pattern of the reference light for reproduction is the phase modulation pattern of the reference light for recording at the time of recording the information to be reproduced with respect to the center of the phase spatial light modulator 117. A point-symmetric pattern is used.

  The light emitted from the light source device 112 is converted into a parallel light beam by the collimator lens 113, passes through the ND filter 114 and the optical rotation optical element 115 in order, and enters the polarization beam splitter 116. The S-polarized component of the light incident on the polarization beam splitter 116 is reflected by the polarization beam splitter surface 116 a and blocked by the spatial light modulator 125. The P-polarized component of the light incident on the polarization beam splitter 116 passes through the polarization beam splitter surface 116a and passes through the phase spatial light modulator 117. At this time, the phase of the light is spatially modulated and reproduced. Reference light for The reproduction reference light is incident on the beam splitter 118. Part of the reproduction reference light that has entered the beam splitter 118 is reflected by the beam splitter surface 118 a, passes through the polarization beam splitter 120, and enters the two-split optical rotation plate 121. Here, the reproduction reference light that has passed through the optical rotation plate 121R of the two-part optical rotation plate 121 becomes B-polarized light, and the reproduction reference light that has passed through the optical rotation plate 121L becomes A-polarized light. The reproduction reference light that has passed through the two-divided optical rotatory plate 121 is reflected by the rising mirror 122, collected by the objective lens 123, and converged behind the hologram layer 225 in the optical information recording medium 1. The optical information recording medium 1 is irradiated. In FIG. 60, the rising mirror 122 is omitted.

  Note that the positioning (servo) of the reference light for reproduction with respect to the optical information recording medium 1 can be performed in the same manner as the positioning of the reference light for recording and the information light during recording.

  As shown in FIG. 62, the B-polarized reproduction reference light 315B that has passed through the optical rotatory plate 121R of the two-divided optical rotatory plate 121 passes through the hologram layer 225 and is a reflection surface at the converging position on the back side of the hologram layer 225. And pass through the hologram layer 225 again. At this time, the reproduction reference light 315B after being reflected by the reflecting surface passes through the portion irradiated with the recording reference light 311A during recording in the interference region 313 and has the same modulation pattern as the recording reference light 311A. It is light. Accordingly, the reproduction light 316B corresponding to the information light 312A at the time of recording is generated from the interference region 313 by the reproduction reference light 315B. The reproduction light 316B travels toward the objective lens 123 side.

  Similarly, the A-polarized reproduction reference light 315A that has passed through the optical rotatory plate 121L of the two-part optical rotatory plate 121 passes through the hologram layer 225, and is reflected by the reflecting surface at the converging position on the back side of the hologram layer 225, Pass through layer 225 again. At this time, the reproduction reference light 315A after being reflected by the reflecting surface passes through the portion irradiated with the recording reference light 311B during recording in the interference region 313 and has the same modulation pattern as the recording reference light 311B. It is light. Therefore, reproduction light 316A corresponding to the information light 312B at the time of recording is generated from the interference region 313 by the reproduction reference light 315A. The reproduction light 316A travels toward the objective lens 123 side.

  The B-polarized reproduction light 316B passes through the objective lens 123 and then passes through the optical rotation plate 121R of the two-part optical rotation plate 121 to become P-polarized light. The A-polarized reproduction light 316A passes through the objective lens 123 and then passes through the optical rotatory plate 121L of the two-split optical rotatory plate 121 to become P-polarized light. The reproduction light that has passed through the two-split optical rotation plate 121 enters the polarization beam splitter 120, passes through the polarization beam splitter surface 120 a, and enters the beam splitter 118. Part of the reproduction light that has entered the beam splitter 118 passes through the beam splitter surface 118 a, passes through the imaging lens 132, and enters the CCD array 133. As shown in FIG. 60, by adjusting the position of the imaging lens 132, the imaging state of the reproduction light with respect to the CCD array 133 can be adjusted.

  An on / off pattern is formed on the CCD array 133 by the spatial light modulator 125 during recording, and information is reproduced by detecting this pattern. When a plurality of pieces of information are recorded on the hologram layer 225 by changing the modulation pattern of the reference light for recording, the modulation pattern of point symmetry with the modulation pattern of the reference light for reproduction is included in the plurality of pieces of information. Only information corresponding to the recording reference beam is reproduced.

Further, part of the reproduction reference light incident on the beam splitter 118 enters the photodetector 119, and a signal APC _ref is generated by the APC circuit 146 based on the output signal of the photodetector 119. Based on the signal APC _ref , APC is performed so that the amount of reproduction reference light irradiated on the optical information recording medium 1 is constant. Specifically, the drive circuit 148 drives the motor 142 to adjust the optical rotation optical element 115 so that the signal APC _ref becomes equal to a predetermined value. Alternatively, at the time of reproduction, the optical rotation optical element 115 may be set so that the light passing through the optical rotation optical element 115 becomes only the P-polarized component, and the output of the light source device 112 may be adjusted to perform APC. . When the light receiving unit of the photodetector 119 is divided into a plurality of regions and the phase spatial light modulator 117 can also adjust the amount of transmitted light, the phase is determined based on the output signal for each light receiving unit of the photodetector 119. The transmitted light amount for each pixel in the spatial light modulator 117 may be adjusted so that the intensity distribution of the reproduction reference light irradiated on the optical information recording medium 1 is uniform.

  In this embodiment, a light source device 112 that can emit laser light of three colors R, G, and B is used, and the CCD array 133 can also detect light of three colors R, G, and B. Further, as the optical information recording medium 1, the same reference light for recording can be obtained by using the optical information recording medium 1 having three hologram layers whose optical characteristics are changed only by light of each color of R, G and B. With this modulation pattern, it is possible to record three types of information at the same location of the optical information recording medium 1, and it is possible to multiplex record more information. An example of a recording medium having three hologram layers as described above is DuPont's HRF-700X059-20 (trade name).

As described above, when information is multiplexed and recorded with light of three colors of R, G, and B, time division is performed for each color of R, G, and B with respect to the same portion of the optical information recording medium 1. To record information. At this time, the modulation pattern of the information light is changed for each color of R, G, and B, but the modulation pattern of the recording reference light is not changed. Here, when each pixel of information light for each color carries binary information, that is, when each pixel is expressed by light or dark, multiplexing of information by light of three colors of R, G, and B is performed. than be recorded, for example, the R MSB (most significant bit), B as LSB (least significant bit), it is possible to record information 8 (= ^{2 3)} values for each pixel. When the spatial light modulator 125 can adjust the amount of transmitted light to three or more levels, and each pixel of information light for each color carries information of n (n is an integer of 3 or more) gradation information, R, G, B than to perform multiplex recording of information by three colors of light, it is possible to record the information of n ³ values per pixel.

  Information can be reproduced in various ways as described below when information is multiplexed and recorded with light of three colors of R, G, and B. That is, if the reproduction reference light is any one color of R, G, and B, only information recorded using the same color light as the reproduction reference light is reproduced. When the reproduction reference light is light of any two colors of R, G, and B, only two types of information recorded using the same two colors of light as the reproduction reference light are reproduced. . These two types of information are separated into information for each color in the CCD array 133. When the reproduction reference light is light of three colors R, G, and B, all three types of information recorded using the light of three colors are reproduced. These three types of information are separated into information for each color in the CCD array 133. When the optical information recording medium 1 has layers for each color of R, G, and B, multiple recording is performed by phase encoding multiplexing in each color layer. Thereby, there is an effect that a reproduction image of a pattern for each color of R, G, B can be obtained for each modulation pattern of the phase of the reference light.

  Next, referring to FIG. 63 and FIG. 64, the direct read after write (hereinafter referred to as DRAW) function of the optical information recording / reproducing apparatus according to the present embodiment and the multiplexing are described. The function of write power control (hereinafter referred to as WPC) during recording will be described.

  First, the DRAW function will be described. The DRAW function is a function for reproducing recorded information immediately after recording information. This function makes it possible to verify the recorded information immediately after recording the information.

  Hereinafter, the principle of the DRAW function in the present embodiment will be described with reference to FIG. 55 and FIG. First, in the present embodiment, when the DRAW function is used, the modulation pattern of the recording reference light is a point-symmetric pattern with respect to the center of the phase spatial light modulator 117. At the time of recording, the A-polarized recording reference light 311A that has passed through the optical rotatory plate 121L of the two-split optical rotator 121 and the A-polarized information light 312A that has passed through the optical rotator 121R of the two-split optical rotator 121 within the hologram layer 225 The B-polarized recording reference light 311B that has passed through the optical rotatory plate 121R of the two-split optical rotator 121 and the B-polarized information light 312B that has passed through the optical rotatory plate 121L of the two-split optical rotator 121 interfere with each other. Are recorded in a volume in the hologram layer 225.

  As described above, when the interference pattern starts to be recorded in the hologram layer 225, the A-polarized recording reference light 311A that has passed through the optical rotation plate 121L of the two-part optical rotation plate 121 is reflected at the convergence position on the back side of the hologram layer 225. The A-polarized reproduction light is generated from the portion where the interference pattern is recorded by the recording reference light 311B by the light reflected by the surface. The reproduction light travels toward the objective lens 123 side, passes through the objective lens 123, passes through the optical rotation plate 121L of the two-part optical rotation plate 121, and becomes P-polarized light. Similarly, the B-polarized recording reference light 311B that has passed through the optical rotatory plate 121R of the two-divided optical rotatory plate 121 is interfered by the recording reference light 311A by the light reflected by the reflecting surface at the converging position on the back side of the hologram layer 225. B-polarized reproduction light is generated from the portion where the pattern is recorded. The reproduction light travels toward the objective lens 123 side, passes through the objective lens 123, passes through the optical rotation plate 121R of the two-part optical rotation plate 121, and becomes P-polarized light. The reproduction light that has passed through the two-split optical rotation plate 121 enters the polarization beam splitter 120, passes through the polarization beam splitter surface 120 a, and enters the beam splitter 118. Part of the reproduction light incident on the beam splitter 118 passes through the beam splitter surface 118a, passes through the imaging lens 132, and enters the CCD array 133 to be detected. In this way, the recorded information can be reproduced immediately after the information is recorded.

  In FIG. 63, reference numeral 321 shows an example of the relationship between the elapsed time after the start of information recording at one location of the optical information recording medium 1 and the output level of the CCD array 133. Thus, the output level of the CCD array 133 gradually increases according to the degree of recording of the interference pattern on the optical information recording medium 1 after the start of information recording, reaches a maximum value at a certain time, and thereafter gradually increases. Get smaller. It can be said that the higher the output level of the CCD array 133, the higher the diffraction efficiency due to the recorded interference pattern (hereinafter referred to as a recording pattern). Therefore, at the time of recording, when the output level of the CCD array 133 reaches an output level corresponding to the desired diffraction efficiency, the recording is stopped, whereby a recording pattern having a desired diffraction efficiency can be formed.

  In the present embodiment, preferably, a test area is appropriately provided in the optical information recording medium 1 in order to form a recording pattern having a desired diffraction efficiency using the DRAW function as described above. Similar to the data area 7, the test area is an area where information can be recorded by holography. Preferably, the controller 90 performs the following operation when recording information. That is, the controller 90 performs an operation for recording predetermined test data in the test area in advance, and detects the profile of the output level of the CCD array 133 as shown in FIG. At this time, preferably, the output of the light source device 112 and the ratio of the light quantity of the recording reference light and the information light are changed to record the test data and the output level of the CCD array 133 at a plurality of locations in the test area. For example, as shown by reference numerals 321 to 323 in FIG. 63, a plurality of profiles are detected, and an optimum profile is selected from the profiles, and the actual information is obtained under the conditions corresponding to the selected profile. Start recording.

  Further, the controller 90 obtains the output level corresponding to the desired diffraction efficiency or the time from the start of recording at which the output level is obtained based on the detected profile or the selected profile. When recording actual information, the controller 90 monitors the output level of the CCD array 133 and stops recording when the output level reaches an output level corresponding to a desired diffraction efficiency obtained in advance. Alternatively, the controller 90 records the actual information when the elapsed time after the start of recording reaches the time from the start of recording at which an output level corresponding to the desired diffraction efficiency obtained in advance is obtained. To stop. With such an operation, it is possible to form a recording pattern with a desired diffraction efficiency on the optical information recording medium 1.

  Further, as described above, in the present embodiment, the recorded information can be collated using the DRAW function. FIG. 64 shows a circuit configuration necessary for performing this collation in the optical information recording / reproducing apparatus according to the present embodiment. As shown in this figure, the optical information recording / reproducing apparatus receives information to be recorded from the controller 90, and this information is data of the modulation pattern of the spatial light modulator (referred to as SLM in FIG. 64) 125. The encoder 331 that encodes the output data of the CCD array 133 so that the output data of the CCD array 133 becomes data that is given to the encoder 331 from the controller 90, and the data that is given to the encoder 331 from the controller 90. And a comparison unit 333 that compares the data obtained by the decoder 322 and sends information of the comparison result to the controller 90. The comparison unit 333 sends, for example, information on the degree of coincidence of two data to be compared or information on an error rate (error rate) to the controller 90 as information on the comparison result. For example, when the comparison result information sent from the comparison unit 333 is within a range in which the data error can be corrected, the controller 90 continues the recording operation, and the comparison result information indicates the data error. Is outside the repairable range, the recording operation is stopped.

  Thus, since the optical information recording / reproducing apparatus according to the present embodiment has the DRAW function, the sensitivity unevenness of the optical information recording medium 1, the change in the external environmental temperature, the light source device 112, and the like. The recording operation can be performed in the optimum recording state even if there is a disturbance such as fluctuations in output.

  Further, according to the present embodiment, since it has a function of collating recorded information simultaneously with recording of information, high-speed recording can be performed while maintaining high reliability. This function is particularly useful when recording information at a high transfer rate. Reproduction of information in a state where information is not fixed is not preferable because it has the same effect as overwriting and degrades the quality of recorded information. In the verification function in the embodiment, since the confirmation of the recorded information is completed during the recording operation, no problem occurs.

  Next, the WPC function at the time of multiplex recording will be described. When a plurality of pieces of information are multiplexed and recorded at the same location of the optical information recording medium 1 by changing the modulation pattern of the recording reference light, the diffraction efficiency of the previously recorded recording pattern is gradually increased by the subsequent recording. descend. The WPC function in the present embodiment is a function for controlling the recording reference light and the information light at the time of recording so that substantially the same diffraction efficiency can be obtained in each recording pattern for each information to be multiplexed recorded at the time of multiplex recording. is there.

  Here, the diffraction efficiency of the recording pattern is the intensity of the recording reference light and the information light, the irradiation time of the recording reference light and the information light, the intensity ratio of the recording reference light and the information light, the modulation pattern of the recording reference light, A total number of times of recording is performed on the same portion of the optical information recording medium 1, and this depends on parameters such as the number of times of recording. Therefore, in the WPC function, at least one of the plurality of parameters may be controlled. In order to easily perform the control, the intensity and irradiation time of the recording reference light and information light may be controlled. When controlling the intensity of the recording reference light and the information light, the intensity is reduced as recording is performed later. When controlling the irradiation time of the recording reference light and the information light, the irradiation time is shortened as recording is performed later.

In the WPC function according to the present embodiment, based on the output level profile of the CCD array 133 as shown in FIG. Control recording reference light and information light. FIG. 63 shows an example of the irradiation time when the irradiation time of the recording reference light and the information light is controlled. That is, in the example shown in FIG. 63, it is assumed that recording is performed five times at the same location on the optical information recording medium 1, and T ₁ , T ₂ , T ₃ , T ₄ , and T ₅ are recorded for the first time. , The recording reference light and the information light irradiation time during the second recording, the third recording, the fourth recording, and the fifth recording.

  Thus, according to the present embodiment, the diffraction efficiency of each recording pattern for each piece of information to be multiplexed can be made substantially equal.

  By the way, according to the optical information recording / reproducing apparatus according to the present embodiment, a large amount of information can be recorded on the optical information recording medium 1 with high density. This means that if a defect or the like occurs in the optical information recording medium 1 after information is recorded, and part of the information cannot be reproduced, the amount of information lost thereby increases. In the present embodiment, in order to prevent such omission of information and improve reliability, information that applies RAID (Redundant Arrays of Inexpensive Disks) technology may be recorded as described below. It can be done.

  The RAID technology is a technology for improving the reliability of recording by recording data so as to have redundancy by using a plurality of hard disk devices. RAID is classified into five categories from RAID-1 to RAID-5. In the following description, typical RAID-1, RAID-3, and RAID-5 will be described as examples. RAID-1 is a method of writing the same contents to two hard disk devices, and is also called mirroring. RAID-3 is a system in which input data is divided into fixed lengths, recorded on a plurality of hard disk devices, and parity data is generated and written to another hard disk device. RAID-5 increases the data division unit (block) and records one piece of divided data as a data block on one hard disk device, and also adds parity data for the data blocks corresponding to each hard disk device to a parity block. As well as recording in other hard disk devices and distributing the parity blocks to all hard disk devices.

  In the information recording method (hereinafter referred to as a distributed recording method) applying the RAID technology in the present embodiment, the hard disk device in the description of the RAID described above is replaced with the interference area 313 in the optical information recording medium 1, Information is recorded.

  FIG. 65 is an explanatory diagram showing an example of the distributed recording method in the present embodiment. In this example, the information to be recorded on the optical information recording medium 1 is a series of data DATA1, DATA2, DATA3,..., And the same data DATA1, DATA2, DATA3,. Information is recorded in the interference areas 313a to 313e. In each of the interference areas 313a to 313e, a plurality of data is multiplexed and recorded by phase encoding multiplexing. This recording method corresponds to RAID-1. According to this recording method, even if data cannot be reproduced in any of the plurality of interference areas 313a to 313e, data can be reproduced from other interference areas.

  FIG. 66 is an explanatory diagram showing another example of the distributed recording method according to the present embodiment. In this example, information to be recorded on the optical information recording medium 1 is a series of data DATA1, DATA2, DATA3,..., DATA12, and this data is divided and recorded in a plurality of interference areas 313a to 313d. At the same time, parity data for data recorded in the plurality of interference areas 313a to 313d is generated, and this parity data is recorded in the interference area 313e. More specifically, in this recording method, data DATA1 to DATA4 are recorded in the interference areas 313a to 313d, respectively, and parity data PARITY (1-4) for the data DATA1 to DATA4 is recorded in the interference area 313e. DATA5 to DATA8 are recorded in interference areas 313a to 313d, parity data PARITY (5-8) for data DATA5 to DATA8 is recorded in interference area 313e, and data DATA9 to DATA12 are recorded in interference areas 313a to 313d, respectively. Then, parity data PARITY (9-12) for the data DATA9 to DATA12 is recorded in the interference area 313e. In each of the interference areas 313a to 313e, a plurality of data is multiplexed and recorded by phase encoding multiplexing. This recording method corresponds to RAID-3. According to this recording method, even when data cannot be reproduced in any of the plurality of interference areas 313a to 313d, the data can be restored using the parity data recorded in the interference area 313e.

  FIG. 67 is an explanatory diagram showing still another example of the distributed recording method according to the present embodiment. In this example, it is assumed that information to be recorded on the optical information recording medium 1 is a series of data DATA1, DATA2, DATA3,..., DATA12, and this data is divided into a plurality of interference areas 313a to 313e. In addition to recording in the four interference areas, parity data for the recorded data is generated, and the parity data is recorded in the remaining interference areas among the plurality of interference areas 313a to 313e. In this method, the interference area for recording parity data is sequentially changed. More specifically, in this recording method, data DATA1 to DATA4 are recorded in the interference areas 313a to 313d, respectively, and parity data PARITY (1-4) for the data DATA1 to DATA4 is recorded in the interference area 313e. DATA5 to DATA8 are recorded in the interference areas 313a to 313c and 313e, respectively, parity data PARITY (5-8) for the data DATA5 to DATA8 is recorded in the interference area 313d, and the data DATA9 to DATA12 are recorded in the interference areas 313a and 313b, respectively. , 313d, 313e, and parity data PARITY (9-12) for the data DATA9 to DATA12 is recorded in the interference area 313c. In each of the interference areas 313a to 313e, a plurality of data is multiplexed and recorded by phase encoding multiplexing. This recording method corresponds to RAID-5. According to this recording method, even when data cannot be reproduced in any of a plurality of interference areas where data is recorded, data can be restored using parity data.

  For example, the distributed recording method as shown in FIGS. 65 to 67 is performed under the control of the controller 90 as the control means.

  FIG. 68 shows an example of the arrangement of a plurality of interference areas used in the above-described distributed recording method. In this example, the interference areas used in the distributed recording method are a plurality of adjacent interference areas 313 in one track. In this case, it is preferable that the plurality of interference regions 313 used in the distributed recording method be interference regions within a range where in-view access is possible. This is because each interference region 313 can be accessed at high speed.

  FIG. 69 shows another example of the arrangement of a plurality of interference areas used in the above-described distributed recording method. In this example, a plurality of interference areas used in the distributed recording method are a plurality of interference areas 313 that are two-dimensionally adjacent to the radial direction 331 and the track direction 332 of the optical information recording medium 1. In this case, among the plurality of interference regions used in the distributed recording method, the plurality of interference regions 313 adjacent in the track direction 332 are preferably interference regions within the range that can be accessed within the visual field. This is because each interference region 313 adjacent in the track direction 332 can be accessed at high speed.

  In the distributed recording method according to the present embodiment, a series of data may be recorded in a distributed manner in a plurality of interference areas 313 positioned in a jump without being recorded in a plurality of adjacent interference areas 313. .

  Up to this point, the distributed recording method has been described in the case where a plurality of data is multiplexed and recorded in one interference region 313 by phase encoding multiplexing. However, even when a plurality of data is multiplexed and recorded by other methods, the distributed recording method is also used. A recording method can be realized. As an example, with reference to FIG. 70, a description will be given of a distributed recording method in the case where a plurality of data is multiplexed and recorded using a method called shift multiplexing. As shown in FIG. 70, the shift multiplexing is performed by forming a plurality of interference regions 313 with respect to the optical information recording medium 1 so as to be slightly shifted in the horizontal direction and partially overlapping each other. This information is a method of recording multiple information. FIG. 70 shows an example in which a plurality of interference areas 313 used in the distributed recording method are two-dimensionally arranged, but the plurality of interference areas 313 used in the distributed recording method are within the same track. May be arranged adjacent to each other. In FIG. 70, an arrow indicated by reference numeral 334 represents the recording order. In a distributed recording method using multiplexing, data and parity data divided from a series of data are distributed and recorded in a plurality of interference areas 313.

  Also, a distributed recording method can be realized even when a plurality of data is multiplexed and recorded by using both phase encoding multiplexing and shift multiplexing. In FIG. 71, in the track direction 332 of the information recording medium 1, interference areas 313 for multiplexing and recording information by phase encoding multiplexing are formed without overlapping each other, and in the radial direction 331 of the information recording medium 1, shift multiplexing is performed. An example is shown in which adjacent interference regions 313 are slightly shifted in the horizontal direction and partly overlapped by using mixing. Each interference region 313 in this example is treated in the same manner as the interference regions 313a to 313e in FIGS.

  Next, with reference to FIG. 72 and FIG. 73, a juke apparatus using the optical information recording / reproducing apparatus according to the present embodiment will be described as an application example of the optical information recording / reproducing apparatus according to the present embodiment. The juke device is a large-capacity information recording / reproducing device having an autochanger mechanism for exchanging recording media.

  72 is a perspective view showing the appearance of the juke device, and FIG. 73 is a block diagram showing the circuit configuration of the juke device. This juke device includes a front panel block 401 provided on the entire surface of the juke device, a robotics block 402 constituting the inside of the juke device, a rear panel block 403 provided on the back side of the juke device, and an interior of the juke device. And a first disk array 404 in which a plurality of optical information recording / reproducing devices are connected, a second disk array 405 in which a plurality of optical information recording / reproducing devices are also connected, and a juke device. And a power supply block 406 for supplying predetermined power.

  The front panel block 401 includes a front door 407 that is opened and closed when the disk arrays 404 and 405 are exchanged, and a front panel 408.

  The front panel 408 includes a keypad 409 having various operation keys, a display 410 for displaying an operation mode, for example, a functional switch 411 for designating opening / closing of the front door 407, and the optical information recording medium 1 A mail slot 412 serving as an insertion and discharge port of the optical information recording medium and the optical information recording medium 1 inserted through the mail slot 412 are transferred to a mail box (not shown), and the optical information recording medium 1 to be ejected is transferred from the mail box to the mail slot 412. And a full sensor 414 for detecting that the optical information recording medium 1 inserted in the juke apparatus has reached a specified number.

  The front door 407 controls the opening / closing of the front door 407 according to the operation of the door sensor 415 for detecting the opening / closing state of the front door 407, the door lock solenoid 416 for controlling the opening / closing of the front door 407, and the functional switch 411. An interlock switch 417 is provided.

  The robotics block 402 is provided so as to be stacked on the lower magazine 421 in which, for example, ten optical information recording media 1 can be stored, and on the upper surface of the lower magazine 421, for example, 10 It has an upper magazine 422 that can store one optical information recording medium 1 and a controller block 423 that controls the entire juke apparatus.

  The robotics block 402 controls the grip operation motor 424 for controlling the grip operation of a manipulator (not shown) that moves the optical information recording medium 1 inserted in the juke apparatus to a predetermined location, and the controller block 423. Accordingly, a grip operation motor controller 425 for controlling the rotation speed and rotation direction of the grip operation motor 424 and a grip for detecting the rotation speed and rotation direction of the grip operation motor 424 and supplying the detected data to the controller block 23. And an operation encoder 426. The robotics block 402 includes a rotation operation motor 427 for controlling the rotation of the manipulator in the clockwise direction, the counterclockwise direction, or the left-right direction, and the rotation number of the rotation operation motor 427 according to the control of the controller block 423. A rotation operation motor controller 428 for controlling the rotation direction, and a rotation operation encoder 429 for detecting the rotation speed and rotation direction of the rotation operation motor 427 and supplying the detected data to the controller block 423 are provided. The robotics block 402 includes a vertical movement motor 430 for controlling the movement of the manipulator in the vertical direction, and a vertical movement motor for controlling the number of rotations and the rotation direction of the vertical movement motor 430 according to the control of the controller block 423. The controller 431 includes a vertical motion encoder 432 that detects the rotational speed and rotational direction of the vertical motion motor 430 and supplies the detected data to the controller block 423.

  The robotics block 402 includes a transfer motor controller 433 that controls the rotation speed and rotation direction of the transfer motor 413 for performing the insertion / ejection operation of the optical information recording medium 1 via the mail slot 412, and a clear path sensor 434. And a clear pass emitter 420.

  The rear panel block 403 includes an RS232C connector terminal 435 that is an input / output terminal for serial transmission, a connector terminal 436 for UPS (Uninterruptible Power System), and a first SCSI (Small Computer System) that is an input / output terminal for parallel transmission. Interface) connector terminal 437, a second SCSI connector terminal 438, which is also an input / output terminal for parallel transmission, and an AC (alternating current) power connector terminal 439 connected to a commercial power source.

  The RS232C connector terminal 435 and the UPS connector terminal 436 are connected to the controller block 423, respectively. The controller block 423 converts the serial data supplied via the RS232C connector terminal 435 into parallel data and supplies it to the disk arrays 404 and 405, and converts the parallel data from the disk arrays 404 and 405 into serial data. The converted signal is supplied to the RS232C connector terminal 435.

  The SCSI connector terminals 437 and 438 are connected to the controller block 423 and the disk arrays 404 and 405, respectively. Each disk array 404, 405 directly transfers data via each SCSI connector terminal 437, 438, and the controller block 423 converts the parallel data from each disk array 404, 405 into serial data, and for RS232C. The connector terminal 435 is supplied.

  The AC power connector terminal 439 is connected to the power supply block 406. The power supply block 406 forms + 5V, + 12V, + 24V, and −24V electric power based on the commercial power supplied via the AC power connector terminal 439, and supplies it to the other blocks. .

  A manipulator (not shown) includes a carriage having a gripper that performs operations such as picking up the optical information recording medium 1 transferred to the mail box via the mail slot 412 one by one, a carriage holding unit that holds the carriage, a carriage And a drive unit for controlling rotation up and down, left and right, front and rear, and rotation. Inside the juke device, there are four pillars that are formed in a substantially rectangular shape on the bottom surface, and are erected from the four corners of the rectangle to the top surface of the juke device so as to be perpendicular to the bottom surface. Is provided. The carriage holding unit holds the carriage so that it can be rotated back and forth, and freely, and has a column support unit that holds the column at both ends so that the carriage holding unit can move up and down along the four columns. ing.

  The carriage driving unit generates a driving force for controlling the movement of such a manipulator up and down along the support column, generates a driving force for controlling the carriage to the left, right, back and forth, and rotation, and records optical information with a gripper. A driving force for picking up the medium 1 is generated.

  As shown in FIG. 72, one end of the front door 407 is cantilevered by a hinge 450 so that the front door 407 can be opened and closed. By opening and closing the front door 407, the lower magazine 421, the upper magazine 422, the first, second The disk arrays 404 and 405 can be pulled out or mounted. Each of the magazines 421 and 422 has a box shape for storing ten optical information recording media 1 stored in cartridges in a stacked manner in parallel with the bottom surface of the juke device. The medium 1 is inserted from the back side of each magazine 421, 422 (the side opposite to the front side where the front door 407 is provided when each magazine 421, 422 is attached to the juke device). ing. The optical information recording medium 1 is mounted at once by the user taking out the magazines 421 and 422 and manually storing them, and mounting the magazines 421 and 422 storing the optical information recording medium 1 in the juke apparatus. Can do. Further, by inserting the optical information recording medium 1 through the mail slot 412, the inserted optical information recording medium 1 is transferred to the mail box, and the manipulator uses the optical information recording medium 1 transferred to the mail box. The magazines 421 and 422 are mounted. As a result, the optical information recording medium 1 can be automatically mounted in each magazine 421, 422.

  Each of the first and second disk arrays 404 and 405 includes a RAID controller and a drive array configured by connecting first to fifth optical information recording / reproducing apparatuses.

  Each optical information recording / reproducing apparatus has a disc insertion / ejection port, and the optical information recording medium 1 is inserted into or ejected from each optical information recording / reproduction device via the disc insertion / ejection port. It has come to be. The RAID controller is connected to the controller block 423, and controls each optical information recording / reproducing apparatus according to the RAID1, RAID3, or RAID5 recording system under the control of the controller block 423. Note that each recording method of RAID1, RAID3, and RAID5 is selected by a key operation of a keypad 409 provided on the front panel 408.

  In this juke apparatus, data is recorded by using a disk array 404, 405 by a RAID 1, RAID 3 or RAID 5 recording method. In order to record data in this way, it is necessary to mount the optical information recording medium 1 in advance in the juke device. There are the following two methods for attaching the optical information recording medium 1 to the juke device.

  72, as shown in FIG. 72, the front door 407 is opened, the lower magazine 421 and the upper magazine 422 are taken out, and the optical information recording medium 1 is manually inserted into these magazines 421 and 422. It is a method of wearing.

  The second mounting method is a method of mounting the optical information recording medium 1 one by one via the mail slot 412 shown in FIG. When the optical information recording medium 1 is loaded in the mail slot 412, the controller block 423 detects this, and drives and controls the transfer motor 413 to transfer the optical information recording medium 1 to the mail box. When the optical information recording medium 1 is transferred to the mail box, the controller block 423 controls the movement of the manipulator in the direction in which the mail box is provided and controls the movement of the manipulator for grip operation. By driving and controlling the motor 424, the optical information recording medium 1 picked up by the gripper provided in the manipulator is controlled to move to the empty disk storage portion of the magazines 421 and 422. Then, the grip operation motor 424 is driven and controlled, and the optical information recording medium 1 picked up by the gripper is released in the disk storage portion. The controller block 423 controls each unit so as to repeatedly perform such a series of mounting operations each time the optical information recording medium 1 is inserted through the mail slot 412.

  As described above, when the optical information recording medium 1 is mounted on each magazine 421, 422 by the first mounting method or the second mounting method, the controller block 423 controls the manipulator to control the lower magazine 421 or the upper magazine. The optical information recording medium 1 stored in 422 is transferred to the first disk array 404 or the second disk array 405. Each of the disk arrays 404 and 405 can be loaded with five optical information recording media 1, and five of the twenty optical information recording media 1 stored in the respective magazines 421 and 422 by a manipulator. One disk is mounted on the first disk array 404 and the other five disks are mounted on the second disk array 405.

  When recording data, the user operates the keypad 409 to select a desired recording method from among RAID1, RAID3, or RAID5 recording methods, and operates the keypad 409 to record data. Specify the start. Data to be recorded is supplied to the disk arrays 404 and 405 via the RS232C connector terminal 435 or the first and second SCSI connector terminals 437 and 438. When the start of data recording is designated, the controller block 423 is configured to perform data recording according to the selected recording method via a RAID controller provided in each of the disk arrays 404 and 405. Each disk array 404 and 405 is controlled.

  In this juke device, the RAID hard disk device using a conventional hard disk device is replaced with five optical information recording / reproducing devices provided in each of the disk arrays 404 and 405, and a RAID 1, RAID 3 or RAID 5 recording system is used. Data is recorded according to the recording method selected from the above. In this juke device, the data interface is not limited to those mentioned in the above description.

  Incidentally, in the optical information recording / reproducing apparatus according to the present embodiment, copy protection and confidentiality can be easily realized as in the first embodiment. Also, the optical information recording medium 1 in which various types of information (for example, various types of software) having different reference light modulation patterns are recorded is provided to the user, and each type of information can be reproduced according to the user's request. It is possible to realize an information distribution service in which light modulation pattern information is separately provided as key information for a fee.

  Further, the modulation pattern of the phase of the reference light that becomes key information for extracting predetermined information from the optical information recording medium 1 may be created based on information unique to the individual who is the user. Information unique to an individual includes a personal identification number, a fingerprint, a voiceprint, and an iris pattern.

  FIG. 74 shows an example of the configuration of the main part when the optical information recording / reproducing apparatus according to the present embodiment creates the phase modulation pattern of the reference light based on the individual unique information as described above. Is shown. In this example, the optical information recording / reproducing apparatus inputs a personal information input unit 501 for inputting individual unique information such as a fingerprint, and modulates the phase of the reference light based on the information input from the personal information input unit 501. A phase modulation pattern encoder 502 that drives a phase spatial modulator 117 by creating a pattern and giving information of the created modulation pattern to the phase spatial modulator 117 as necessary when recording or reproducing information. When the card 504 in which the modulation pattern information created by the phase modulation pattern encoder 502 is recorded is issued and the card 504 is mounted, the modulation pattern information recorded in the card 504 is phase-shifted. A card issuing / input unit 503 to be sent to the modulation pattern encoder 502;

  In the example shown in FIG. 74, when the user records information on the optical information recording medium 1 using the optical information recording / reproducing apparatus according to the present embodiment, a fingerprint or the like is given to the personal information input unit 501. Is input, the phase modulation pattern encoder 502 creates a modulation pattern of the phase of the reference light based on the information input from the personal information input unit 501, and phase spatial modulation is performed when information is recorded. Information on the created modulation pattern is given to the device 117 to drive the phase spatial modulator 117. Thereby, information is recorded on the optical information recording medium 1 in association with the modulation pattern of the phase of the reference light created based on the unique information of the individual who is the user. Further, the phase modulation pattern encoder 502 sends information on the created modulation pattern to the card issuing / input unit 503, and the card issuing / input unit 503 issues a card 504 on which the information on the modulation pattern sent is recorded.

  In order to reproduce the information recorded as described above from the optical information recording medium 1, the user inputs individual unique information to the personal information input unit 501 or the card 504 in the same manner as at the time of recording. Is attached to the card issuing / input unit 503.

  When individual specific information is input to the personal information input unit 501, the phase modulation pattern encoder 502 creates a modulation pattern of the phase of the reference light based on the information input from the personal information input unit 501. At the time of reproducing information, information on the created modulation pattern is given to the phase spatial modulator 117 to drive the phase spatial modulator 117. At this time, if the modulation pattern of the light phase at the time of recording matches the modulation pattern of the phase of the reference light at the time of reproduction, desired information is reproduced. In order to prevent the phase modulation pattern encoder 502 from creating different modulation patterns at the time of recording and at the time of reproduction even if the same individual specific information is input to the personal information input unit 501, Even if the information input from the information input unit 501 is different to some extent, the phase modulation pattern encoder 502 may generate the same modulation pattern.

  On the other hand, when the card 504 is mounted in the card issuing / input unit 503, the card issuing / input unit 503 sends the modulation pattern information recorded on the card 504 to the phase modulation pattern encoder 502, and the phase modulation pattern encoder 502 gives the information of the modulation pattern sent to the phase spatial modulator 117 to drive the phase spatial modulator 117. Thereby, desired information is reproduced.

  Other configurations, operations, and effects in the present embodiment are the same as those in the first embodiment.

  The present invention is not limited to the above embodiments. For example, in the above embodiments, address information and the like are recorded in advance in the address / servo area 6 of the optical information recording medium 1 by embossed pits. However, without providing embossed pits in advance, in the address / servo area 6, a portion of the hologram layer 3 close to the protective layer 4 is selectively irradiated with a high-power laser beam to select the refractive index of that portion. The address information or the like may be recorded and the formatting may be performed by changing the data.

  The element for detecting information recorded on the hologram layer 3 is not a CCD array, but a smart optical sensor in which a MOS type solid-state imaging device and a signal processing circuit are integrated on one chip (for example, the document “O plus”). E, September 1996, No. 202, pp. 93 to 99 ”). Since this smart optical sensor has a high transfer rate and a high-speed calculation function, it is possible to perform high-speed reproduction by using this smart optical sensor, for example, reproduction at a transfer rate on the order of G bits / second. Is possible.

  In particular, when a smart optical sensor is used as an element for detecting information recorded on the hologram layer 3, address information or the like is recorded in the address / servo area 6 of the optical information recording medium 1 by embossed pits. Instead, the address information of a predetermined pattern is recorded in advance by the same method as the recording using the holography in the data area 7, and the address information is set in the same state as the reproduction at the time of servo. May be detected by a smart light sensor. In this case, the basic clock and address can be obtained directly from the detection data of the smart light sensor. The tracking error signal can be obtained from information on the position of the reproduction pattern on the smart light sensor. The focus servo can be performed by driving the objective lens 12 so that the contrast of the reproduction pattern on the smart light sensor is maximized. Further, even during reproduction, focus servo can be performed by driving the objective lens so that the contrast of the reproduction pattern on the smart light sensor is maximized.

  In each embodiment, the modulation pattern information and wavelength information of the reference light may be given to the controller 90 from an external host device.

It is explanatory drawing which shows the structure of the pick-up in the optical information recording / reproducing apparatus based on the 1st Embodiment of this invention, and an optical information recording medium. 1 is a block diagram showing an overall configuration of an optical information recording / reproducing apparatus according to a first embodiment of the present invention. It is a block diagram which shows the structure of the detection circuit in FIG. It is explanatory drawing which shows the state at the time of the servo of the pick-up shown in FIG. It is explanatory drawing for demonstrating the polarized light used in the 1st Embodiment of this invention. It is explanatory drawing which shows the state at the time of recording of the pick-up shown in FIG. It is explanatory drawing which shows the state of the light in the pickup of the state shown in FIG. It is explanatory drawing which shows the state of the light in the pickup of the state shown in FIG. It is explanatory drawing which shows the state at the time of reproduction | regeneration of the pick-up shown in FIG. It is explanatory drawing which shows the state of the light in the pickup of the state shown in FIG. It is explanatory drawing which shows the state of the light in the pickup of the state shown in FIG. FIG. 2 is an explanatory diagram for explaining a method of recognizing a reference position in a reproduction light pattern from detection data of a CCD array in FIG. 1. FIG. 2 is an explanatory diagram for explaining a method of recognizing a reference position in a reproduction light pattern from detection data of a CCD array in FIG. 1. It is explanatory drawing which shows the pattern of the information light and the pattern of reproduction | regeneration light in the pick-up shown in FIG. It is explanatory drawing which shows the content of the data discriminate | determined from the pattern of the reproduction | regeneration light detected by the pickup shown in FIG. 1, and the ECC table corresponding to this data. In the light absorption spectrum of a hole burning material, it is a characteristic diagram showing a state in which a decrease in light absorptance occurs at a plurality of wavelength positions by irradiation with light of a plurality of wavelengths. It is explanatory drawing which shows the structure of the pick-up in the 3rd Embodiment of this invention. It is a top view which shows the structure of the optical unit containing each element which comprises the pick-up in the 3rd Embodiment of this invention. It is explanatory drawing which shows an example of the optical element for optical rotation in FIG. It is explanatory drawing which shows the structure of the pick-up which enabled use of the laser beam of 3 colors in the 3rd Embodiment of this invention. It is a top view which shows the slide feed mechanism of the optical unit shown in FIG. FIG. 22 is a partially cutaway side view showing the slide feed mechanism shown in FIG. 21 in a stationary state. FIG. 22 is a partially cutaway side view showing the slide feed mechanism shown in FIG. 21 when the optical unit is slightly displaced. It is explanatory drawing which shows operation | movement of the actuator shown in FIG. It is explanatory drawing which shows the moving direction by the seek of the objective lens in the pick-up shown in FIG. 17, and the direction of in-field access. It is explanatory drawing for demonstrating positioning of the reference beam and information beam in the 3rd Embodiment of this invention. It is explanatory drawing showing an example of the locus | trajectory of the center of an objective lens at the time of accessing the several location in an optical information recording medium using the movement by a seek and access within a visual field together in the 3rd Embodiment of this invention. It is a top view which shows the cartridge which accommodates the optical information recording medium in the 3rd Embodiment of this invention. FIG. 29 is a plan view of the cartridge shown in FIG. 28 in a state where a shutter is opened. It is a top view which shows the example which has arrange | positioned two optical units so as to oppose one side of the optical information recording medium in the 3rd Embodiment of this invention. It is a top view which shows the example which provided the four optical units in the 3rd Embodiment of this invention. FIG. 32 is a cross-sectional view taken along line AA ′ in FIG. 31. FIG. 32 is a sectional view taken along line BB ′ of FIG. 31. It is a top view which shows the example which provided 16 optical units in the 3rd Embodiment of this invention. It is sectional drawing of the half of the air gap type optical information recording medium in the 3rd Embodiment of this invention. FIG. 10 is an exploded perspective view of a half of an air gap type optical information recording medium according to a third embodiment of the present invention. It is a perspective view of the half of the air gap type optical information recording medium in the 3rd Embodiment of this invention. It is sectional drawing of the half of the transparent substrate gap type optical information recording medium in the 3rd Embodiment of this invention. It is a disassembled perspective view of the half of the transparent substrate gap type optical information recording medium in the 3rd Embodiment of this invention. It is a perspective view of the half of the transparent substrate gap type optical information recording medium in the 3rd Embodiment of this invention. It is sectional drawing of the optical information recording medium of the thickness of 1.2 mm in the single-sided type in the 3rd Embodiment of this invention. It is sectional drawing of the optical information recording medium of the type with a thickness of 0.6 mm in the single-sided type in the 3rd Embodiment of this invention. FIG. 43 is an explanatory diagram showing a method of irradiating recording reference light and information light to the single-sided optical information recording medium shown in FIG. 41 or FIG. It is sectional drawing of the optical information recording medium of a double-sided type and a transparent substrate gap type in the 3rd Embodiment of this invention. It is sectional drawing of the optical information recording medium of a double-sided type and air gap type in the 3rd Embodiment of this invention. FIG. 46 is an explanatory diagram showing a method of irradiating recording reference light and information light to the double-sided type optical information recording medium shown in FIG. 44 or 45. It is explanatory drawing which shows a single-sided type optical disk. FIG. 48 is an explanatory diagram showing a case where the optical disc shown in FIG. 47 is used in the optical information recording / reproducing apparatus according to the third embodiment of the present invention. It is explanatory drawing which shows a double-sided type optical disk. FIG. 50 is an explanatory diagram showing a case where the optical disc shown in FIG. 49 is used in the optical information recording / reproducing apparatus according to the third embodiment of the present invention. 1 is a perspective view showing a schematic configuration of a general recording / reproducing system that performs phase encoding multiplexing. FIG. It is explanatory drawing which shows a mode that an interference fringe is formed in a hologram recording medium by interference of information light and reference light. It is explanatory drawing which shows the state of the pickup at the time of the servo in the 3rd Embodiment of this invention. It is explanatory drawing which shows the state of the light in the optical disk vicinity in the case of recording and reproducing | regenerating using a normal optical disk with the optical information recording / reproducing apparatus which concerns on the 3rd Embodiment of this invention. It is explanatory drawing which shows the state of the pick-up at the time of recording in the 3rd Embodiment of this invention. It is explanatory drawing which shows the state of the light of the optical information recording medium at the time of recording in the 3rd Embodiment of this invention. It is explanatory drawing which shows the state of the light of the optical information recording medium at the time of recording in the 3rd Embodiment of this invention. It is explanatory drawing which shows the state of the pick-up at the time of fixing in the 3rd Embodiment of this invention. It is explanatory drawing which shows the state of the light of the optical information recording medium vicinity at the time of fixing in the 3rd Embodiment of this invention. It is explanatory drawing which shows the state of the pick-up at the time of reproduction | regeneration in the 3rd Embodiment of this invention. It is explanatory drawing which shows the state of the light of the optical information recording medium vicinity at the time of reproduction | regeneration in the 3rd Embodiment of this invention. It is explanatory drawing which shows the state of the light of the optical information recording medium vicinity at the time of reproduction | regeneration in the 3rd Embodiment of this invention. It is explanatory drawing for demonstrating the direct read after write function and the write power control function at the time of multiplex recording which the optical information recording / reproducing apparatus concerning the 3rd Embodiment of this invention has. It is a block diagram which shows a circuit structure required in order to perform collation in the optical information recording / reproducing apparatus which concerns on the 3rd Embodiment of this invention. It is explanatory drawing which shows an example of the distributed recording method in the 3rd Embodiment of this invention. It is explanatory drawing which shows the other example of the distributed recording method in the 3rd Embodiment of this invention. It is explanatory drawing which shows the further another example of the dispersion | distribution recording method in the 3rd Embodiment of this invention. It is explanatory drawing which shows an example of arrangement | positioning of the some interference area used with the dispersion | distribution recording method in the 3rd Embodiment of this invention. It is explanatory drawing which shows the other example of arrangement | positioning of several interference area | region used with the dispersion | distribution recording method in the 3rd Embodiment of this invention. It is explanatory drawing for demonstrating the distributed recording method in the case of carrying out the multiple recording of several data using shift multiplexing in the 3rd Embodiment of this invention. It is explanatory drawing for demonstrating the dispersion | distribution recording method in the case of carrying out multiple recording of several data using both phase encoding multiplexing and shift multiplexing in the 3rd Embodiment of this invention. It is a perspective view which shows the external appearance of the juke apparatus as an application example of the optical information recording / reproducing apparatus which concerns on the 3rd Embodiment of this invention. FIG. 73 is a block diagram showing a circuit configuration of the juke device shown in FIG. 72. The block diagram which shows an example of a structure of the principal part at the time of making it produce the modulation pattern of the phase of a reference light based on a person's intrinsic | native information in the optical information recording / reproducing apparatus which concerns on the 3rd Embodiment of this invention It is. It is a perspective view which shows the schematic structure of the recording / reproducing system in the conventional digital volume holography.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical information recording medium, 2 ... Transparent substrate, 3 ... Hologram layer, 4 ... Protective layer, 5 ... Reflective film, 6 ... Address servo area, 7 ... Data area, 10 ... Optical information recording / reproducing apparatus, 11 ... Pickup , 12 ... objective lens, 14 ... two-divided optical rotation plate, 17 ... phase spatial light modulator, 18 ... spatial light modulator, 20 ... CCD array, 25 ... light source device.

Claims (6)

An optical information recording method for recording information on an optical information recording medium having an information recording layer on which information is recorded using holography,
Information light carrying information is generated by spatially modulating the light beam emitted from the light source with the two-dimensional pattern information,
Using a light beam emitted from the light source, to generate a recording reference light,
Irradiating the information recording layer with the information light and the recording reference light so that information is recorded by an interference pattern due to interference between the information light and the recording reference light on the information recording layer;
The optical information recording method, wherein the two-dimensional pattern information includes reference position information indicating a reference position of the two-dimensional pattern information.   The information light and the recording reference light are irradiated from the same surface side of the information recording layer so that the optical axis of the information light and the optical axis of the recording reference light are on the same line. The optical information recording method according to claim 1, wherein:   3. The optical information recording method according to claim 1, wherein the reference position information includes a two-dimensional pattern serving as error data as a two-dimensional pattern of information to be recorded. Using holography from an optical information recording medium having an information recording layer in which information is recorded by an interference pattern due to interference between information light carrying information and recording reference light by spatially modulating with two-dimensional pattern information An optical information reproducing method for reproducing information,
Using the luminous flux emitted from the light source, the reproduction reference light is generated,
Irradiating the reproduction reference light to the information recording layer,
Detecting reproduction light generated from the information recording layer by irradiation with the reproduction reference light,
An optical information reproducing method characterized by recognizing a reference position of the reproduction light based on reference position information indicating a reference position included in the two-dimensional pattern information of the reproduction light.   The reproduction light is such that the optical axis of the reproduction light and the optical axis of the reproduction reference light are located on the same line from the same surface side as the reproduction reference light incident side of the optical information recording medium. The optical information reproducing method according to claim 4, wherein the optical information reproducing method is emitted.   6. The optical information reproducing method according to claim 4, wherein the reference position information includes a two-dimensional pattern serving as error data as a two-dimensional pattern of information to be reproduced.