JP2006171416A - Medium for recording hologram and apparatus for recording and reproducing hologram - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a medium for recording hologram and an apparatus for recording and reproducing hologram performing highly accurate servo and address management while improving a memory capacity. <P>SOLUTION: Grooves 10 comprise track grooves 12 with no modulation for accurately tracing to the grooves, and address grooves 11 having pit sequences modulated by address information representing positions on a disk type hologram recording medium 101. For example, after three track grooves 12 are consecutively arranged, one address groove 11 is arranged, and this combination is repeated after that. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hologram recording medium and a hologram recording / reproducing apparatus.

  Development of a hologram recording / reproducing apparatus for recording data using holography is in progress.

  In the hologram recording / reproducing apparatus, two modulated signal light (data superimposed) and unmodulated reference light are generated from laser light, and these are irradiated to the same location on the hologram recording medium. As a result, the signal light and the reference light interfere on the hologram recording medium, a diffraction grating (hologram) is formed at the irradiation point, and data is recorded on the hologram recording medium.

  By irradiating the recorded hologram recording medium with reference light, diffracted light (reproduced light) is generated from the diffraction grating formed during recording. Since the reproduction light includes data superimposed on the signal light at the time of recording, the recorded signal can be reproduced by receiving this with a light receiving element.

Patent Document 1 discloses an example of a hologram recording medium used in such a hologram recording / reproducing apparatus. The hologram recording medium disclosed in Patent Document 1 includes a recording layer and a reflective layer, and a servo area by an emboss bit and an address area following it are physically formed in the reflective layer. Address information for adjusting the irradiation position of the laser beam is recorded in the address area. A mirror area that is not physically formatted with emboss bits is formed after the address area, and a hologram is recorded on a recording layer corresponding to the mirror area.
JP 2003-178456 A (paragraphs [0016] to [0019], FIG. 3)

  However, in the hologram recording medium described in Patent Document 1, since the hologram cannot be recorded on the recording layer corresponding to the servo area and the address area, there is a problem that this area becomes a redundant area and the recording capacity decreases. is there. On the other hand, in the mirror area, there is a problem that focusing and tracking cannot be performed and address management cannot be performed precisely.

  In view of the circumstances as described above, an object of the present invention is to provide a hologram recording medium and a hologram recording / reproducing apparatus capable of performing highly accurate servo and address management while improving the storage capacity.

A. In order to solve such a problem, the hologram recording medium according to the present invention is a disk-shaped hologram recording medium, and shows a hologram recording layer on which a hologram is recorded, a non-modulated first groove, and a position on the disk. A second groove having a pit row modulated by address information is provided with a reflective layer provided concentrically or spirally.

  In the present invention, the first groove without modulation and the second groove having the pit row modulated by the address information indicating the position on the disk are provided in the reflective layer in a concentric or spiral shape. Servo can always be applied using the second groove, and address information indicating the position on the disk can always be obtained using the second groove. Therefore, highly accurate servo and address management can be performed.

Further, by recording a hologram on the hologram recording layer optically independent from the reflective layer, the hologram can be recorded at the position of the hologram recording layer corresponding to the first groove and the second groove. Therefore, a redundant area can be eliminated from the hologram recording layer, and the storage capacity can be improved. “Recording a hologram on a hologram recording layer optically independent of the reflection layer” means, for example, using a red laser for the reflection layer, a blue laser for the hologram recording layer, and a hologram The recording layer can be realized by using a material that is not exposed to red laser.
(1) It is preferable that the three first grooves are provided between the two adjacent second grooves in the reflective layer.

  With the three first grooves, a tracking error signal corresponding to the tracking error can be accurately obtained, and tracking servo can be performed with high accuracy.

In particular, in hologram recording, since the interval between the grooves is very small compared to the diameter of the hologram, it is easy to make a large number of grooves correspond to the hologram in this way. Therefore, it can be said that application of the above technique is a preferable recording method.
(2) It is preferable that the address information includes first information indicating a radial position on the disk and second information indicating a circumferential position on the disk.

Thereby, address management can be performed with high accuracy.
(3) A sync pattern and a clock pattern are preferably added for each address information.

This eliminates the need for a separate clock generation groove.
(4) Between the hologram recording layer and the reflective layer, a laser beam having a first wavelength for irradiating the hologram recording layer is reflected, and a first laser beam for irradiating the reflective layer is used. It is preferable to provide a wavelength selective reflection layer through which laser light having a wavelength of 2 is transmitted.

The laser beam having the first wavelength irradiated to the hologram recording layer reaches the reflection layer, is reflected by the reflection layer, and returns to the hologram recording layer, thereby generating noise. This noise disturbs the recording / reproducing signal. By providing the wavelength selective reflection layer, such noise can be prevented.
B. A hologram recording / reproducing apparatus according to another aspect of the present invention includes a hologram recording layer on which a hologram is recorded, a non-modulated first groove, and a second pit train modulated by address information indicating a position on the disk. A hologram recording / reproducing apparatus for recording and / or reproducing holograms on a disc-shaped hologram recording medium having a reflective layer provided concentrically or spirally on the hologram recording layer. A first optical system for irradiating a laser beam having a first wavelength and receiving the reflected light, and a laser having a second wavelength that is not sensitive to the reflection layer by the hologram recording layer A second optical system for irradiating the light and receiving the reflected light, and an objective lens for the hologram recording medium, An optical unit common to the first optical system and the second optical system, a first drive system for rotationally driving the hologram recording medium, a second drive system for driving the optical unit in a radial direction, And control means for controlling the first and second drive systems based on the address information obtained via the second optical system.

  In the present invention, the first optical system and the second optical system are integrally provided, and the objective lens for the hologram recording medium has a common optical unit for the first optical system and the second optical system. Thus, since the laser light of the first wavelength and the laser light of the second wavelength are irradiated to the hologram recording medium through a common optical path, the hologram is applied to the hologram recording layer corresponding to a desired address. Can be recorded with high accuracy.

  As described above, according to the present invention, the non-modulated first groove and the second groove having the pit row modulated by the address information indicating the position on the disc are formed in the reflection layer different from the hologram recording layer. Since they are provided concentrically or spirally, highly accurate servo and address management can be performed while improving the storage capacity.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Hologram recording medium)

  FIG. 1 is a plan view of a hologram recording medium according to an embodiment of the present invention, and FIG. 2 is a partial cross-sectional view in the radial direction of the hologram recording medium shown in FIG.

  As shown in FIG. 1, the hologram recording medium 101 has a disk shape, and concentric grooves 10 are provided at intervals of, for example, 1.25 μm on a reflection layer described later. Such a groove 10 may be provided in a spiral shape.

  As shown in FIG. 2, the hologram recording medium 101 has an antireflection film layer 102, a protective layer 103, a recording layer 104, a gap layer 105, a wavelength selective reflection layer 106, a gap layer 107, and a reflection layer 108 laminated in this order. It has a structure.

  The antireflection film layer 102 is used to reduce unnecessary reflected light from the surface of the medium 101.

  The protective layer 103 is a layer for protecting the recording layer 104 from the outside, and is made of, for example, plastic.

The recording layer 104 records the interference fringes as a change in refractive index (or transmittance), and any material that changes the refractive index (or transmittance) according to the intensity of light can be used. It can be used regardless of whether it is an organic material or an inorganic material. However, a non-sensitive laser red laser beam is used. Note that, as the inorganic material, for example, a photorefractive material whose refractive index changes according to the exposure amount by an electro-optic effect such as lithium niobate (LiNbO ₃ ) can be used. As the organic material, for example, a photopolymerization type photopolymer can be used. In the photopolymerization type photopolymer, in the initial state, monomers are uniformly dispersed in the matrix polymer. When this is irradiated with light, the monomer is polymerized at the exposed portion. As the polymer is formed, the monomer moves from the surroundings, and the concentration of the monomer changes depending on the location. As described above, the refractive index (or transmittance) of the recording layer 104 changes according to the exposure amount, so that blue laser light (wavelength 410 nm) or green laser light (wavelength 532 nm) for hologram recording / reproduction indicated by symbol B is used. ) Can be recorded on the hologram recording medium 101 as a change in refractive index (or transmittance).

  The gap layers 105 and 107 are layers for maintaining a predetermined distance between the recording layer 104 and the reflective layer 108, and are made of, for example, plastic.

  The wavelength selective reflection layer 106 allows the servo red laser light R to pass through, but reflects the blue or green laser light B for recording and reproduction. When used with the wavelength selective reflection layer 106, the blue or green laser light B for hologram recording / reproduction does not reach the layer below the wavelength selective reflection layer 106, and therefore the reflected light from the reflection layer 108 disturbs the recording / reproduction signal. The blue or green laser light B acts only on the recording layer 104 to record and reproduce the hologram.

The reflective layer 108 is configured by forming an aluminum thin film on the surface of the plastic (the surface on the gap layer 107 side), for example, and the red laser light R that has passed through the reflective layer 108 is reflected by the surface of the gap layer reflective layer 108. The The groove 10 described above is formed concentrically on the surface of the reflective layer 108.
(Configuration of groove 10)

  FIG. 3 is a schematic plan view showing the groove 10 of the reflective layer 108 shown in FIG.

As shown in FIG. 3, the groove 10 has an unmodulated track groove 12 for accurately tracing the groove and an address having a pit string modulated by address information indicating a position on the disc-shaped hologram recording medium 101. For example, after three track grooves 12 continue, one address groove 11 is arranged, and this combination is repeated thereafter.
(Details of address groove 11)

  FIG. 4 is a diagram showing the contents of the information in the address groove 11.

  As shown in FIG. 4, in this embodiment, one round of the disc-shaped hologram recording medium 101 is divided into 24 areas 20, and the areas are numbered "0" to "23" in the circumferential direction. Yes.

  In each area 20, information of a sync pattern 21, a block number 22 (corresponding to a track number), an angular position 23 (corresponding to a sector), and a clock pattern 24 are arranged from the head of the area 20.

  5A to 5E are diagrams showing details of information in each area 20 of the address groove 11.

  The sync pattern 21 is for synchronizing subsequent signals, and is a unique pattern that does not exist elsewhere. As shown in FIG. 5A, for example, it has a configuration of H level 3 bits and L level 3 bits.

  For example, the innermost address groove is set to “0”, and the address grooves existing from the block number 22 toward the outer periphery are numbered “1”, “2”, “3”,. The numbers are arranged with 14 bits of digital data as shown in FIG. In the digital data at this time, as shown in FIG. 5B, “0” is composed of an HLL 3-bit cell, and “1” is composed of an HHL 3-bit cell.

  The angular position 23 is a number obtained by dividing one round of the disk into 24 areas, and is composed of, for example, 5 bits as shown in FIG. “0” and “1” of the digital data in this portion are the same pattern as the block number.

  The clock pattern 24 is composed of a repetition pattern of H and L bit by bit.

Note that these configurations are merely examples, and there are of course various examples.
(Hologram recording / reproducing device)

  FIG. 6 is a schematic diagram showing the configuration of the hologram recording / reproducing apparatus.

  As shown in FIG. 1, a hologram recording / reproducing apparatus 1000 records and reproduces information on the hologram recording medium 101, and includes an optical unit 100 and a drive control system 200 that drives and controls the optical unit 100. .

  The optical unit 100 includes a recording / reproducing light source 111, a collimating lens 112, a polarization beam splitter 113, a mirror 121, a pinhole 122, a spatial light modulator 123, a mirror 124, a dichroic mirror 125, a concave lens 126, an objective lens 127, and a Faraday element 131. 132, polarization beam splitter 133, imaging device 134, mirror 141, shielding plate 142, phase modulation device 143, servo light source 151, collimator lens 152, grating 153, beam splitter 154, condensing lens 155, cylindrical lens 156, A light receiving element 157 and a servo drive unit 158 are included.

  Here, the recording / reproducing light source 111, collimator lens 112, polarization beam splitter 113, mirror 121, pinhole 122, spatial light modulator 123, mirror 124, dichroic mirror 125, concave lens 126, Faraday elements 131 and 132, polarization The beam splitter 133, the image sensor 134, the mirror 141, the shielding plate 142, and the phase modulation element 143 are the first optical system. The servo light source 151, the collimator lens 152, the grating 153, the beam splitter 154, and the condensing lens 155 The cylindrical lens 156 and the light receiving element 157 are the second optical system.

  The recording / reproducing light source 111 is a laser light source, and for example, a laser diode (LD) having a wavelength of 405 [nm] (blue) or an Nd-YAG laser having a wavelength of 532 [nm] (green) can be used.

  The collimating lens 112 is an optical element that converts the laser light emitted from the recording / reproducing light source 111 into parallel light.

  The polarization beam splitter 113 is an optical element that splits the parallel light incident from the collimator lens 112 into signal light and reference light. The polarization beam splitter 113 emits s-wave signal light toward the mirror 121 and p-wave reference light toward the mirror 141.

  The mirrors 121, 124, and 141 are optical elements that reflect incident light and change its direction.

  The pinhole 122 is an optical element that reduces the beam diameter of the signal light.

  The spatial light modulator 123 is an optical element that superimposes data by spatially (in this case, two-dimensionally) modulating signal light. As the spatial light modulator 123, a transmissive liquid crystal element which is a transmissive element can be used. In addition, it is possible to use a reflection type element such as a DMD (Digital micro mirror), a reflection type liquid crystal, or a GLV (Grating Light Value) element for the spatial light modulator.

  The dichroic mirror 125 is an optical element for making light used for recording / reproducing (laser light from the recording / reproducing light source 111) and light used for servo (laser light from the servo light source 151) the same optical path. The dichroic mirror 125 transmits the recording / reproducing light from the recording / reproducing light source 111 in response to the difference in laser light wavelength between the recording / reproducing light source 111 and the servo light source 151, and the servo from the servo light source 151. Reflects light. The surface of the dichroic mirror 125 is subjected to a thin film treatment such that the recording / reproducing light is totally transmitted and the light used for servo is totally reflected.

  The concave lens 126 is a lens for making the convergence of the signal light different from the reference light. Since only the signal light passes through the concave lens 126, the condensing depth of the signal light and the reference light on the hologram recording medium 101 is different.

  The objective lens 127 is an optical element for condensing both the signal light and the reference light on the hologram recording medium 101.

  The Faraday elements 131 and 132 are optical elements for rotating the polarization plane. The polarization plane of the s-polarized light incident on the Faraday element 131 is rotated by 45 °, and is returned to the original s-polarized light by the Faraday element 132.

  The polarization beam splitter 133 is an optical element that reflects the return light (reproduction light) that is transmitted from the Faraday element 131 and reflected by the hologram recording medium 101 and returned from the Faraday element 132. This is realized by a combination of the Faraday elements 131 and 132 and the polarization beam splitter 133.

  The image sensor 134 is an element for inputting an image of reproduction light.

  The shielding plate 142 is an optical element for shielding a part of the reference light so as not to overlap the recording light.

  The phase modulation element 143 is an optical element for giving the reference light a random phase or a certain phase pattern, and may be called a phase mask. For the phase modulation element 143, a ground glass, a diffuser, or a spatial phase modulator may be used. It is also possible to use a hologram element in which a phase pattern is recorded. Light having a phase pattern is generated by reproduction from the hologram element.

  The servo light source 151 is a light source for performing servo control such as tracking servo and focus servo and reading address address information, and emits laser light having a wavelength different from that of the recording / reproducing light source 111. The servo light source 151 is, for example, a laser diode, and uses, for example, 660 nm (red) having a low sensitivity with respect to the hologram recording medium 101 as an oscillation wavelength.

  The collimating lens 152 is an optical element that converts the laser light emitted from the servo light source 151 into parallel light.

  The grating 153 is an optical element for dividing the laser light emitted from the collimator lens 152 into three beams. Laser light is divided for servo control and reading of address dress information.

  The beam splitter 154 is an optical element that transmits the laser light emitted from the grating 153 and reflects the return light that is reflected from the hologram recording medium 101 and returned.

  The condensing lens 155 is an optical element for condensing the return light from the beam splitter 154 on the light receiving element 157.

  The cylindrical lens 156 is an optical element for converting the beam shape of the laser light emitted from the condensing lens 155 from a circular shape to an elliptic shape.

  The light receiving element 157 is an element, such as a photo detector, for receiving the return light and outputting a tracking error signal for tracking servo control, a focus error signal for focus servo control, and a read signal for address address information.

  The servo drive unit 158 is a drive mechanism for driving the objective lens 127 by the tracking error signal and the focus error signal from the light receiving element 157 to perform tracking control and focus control, and includes driving coils 161 and 162.

  FIG. 7 is a plan view showing the configuration of the light receiving element 157.

  As shown in FIG. 7, the light receiving element 157 is composed of eight elements A to H, and the elements A to D receive reflected light 12a from the track groove 12, which is the center spot of the three laser beams. Reflected light 11a from the address groove 11 is received by E and F, and reflected light 11a from the other address groove 11 is received by the elements G and H.

  The output signal from the light receiving element 157 is input to the signal calculation circuit 201, where the focus error signal and the tracking error signal are calculated as follows.

  Focus error signal = (A + C)-(B + D)

  Tracking error signal = (A + D)-(B + C)

  These focus error signal and tracking error signal are input to the focus servo circuit 202 and the tracking servo circuit 203, respectively.

  The focus servo circuit 202 and the tracking servo circuit 203 control the objective lens 127 to an optimal position by supplying current to the focus coil 162 and the tracking coil 161, respectively, based on the focus error signal and the tracking error signal.

  The signal calculation circuit 201 calculates the address signal as follows.

  Address signal = E + F or G + H

  The address signal is input to the address decoder 204 and input to the next controller 205 as position data on the disk.

  Based on the address data and the signal from the tracking servo circuit 203, the controller 205 outputs a signal for moving the optical unit 100 in the radial direction of the hologram recording medium 101 to the slide servo circuit 206. The slide servo circuit 206 The optical unit 100 is controlled to an optimal position by the motor 207.

  A signal from the controller 205 is also input to the spindle servo circuit 208.

  The hologram recording medium 101 is mounted on a spindle motor 209 and is controlled by the spindle servo circuit 208 so as to have an optimum rotational speed.

By performing such control, good hologram recording / reproduction at a desired position on the hologram recording medium 101 becomes possible.
(Operation of hologram recording / reproducing apparatus 1000)

The outline of the operation of the hologram recording / reproducing apparatus 1000 will be described below.
A. When recording

  An outline of the operation of the hologram recording / reproducing apparatus 1000 during recording will be described.

  The laser light emitted from the recording / reproducing light source 111 is converted into parallel light by the collimator lens 112 and split by the polarization beam splitter 113 into s-wave signal light and p-wave reference light.

  The signal light is reflected by the mirror 121, has a desired beam diameter by the pinhole 122, and is spatially intensity modulated by the spatial light modulator 123. The laser light modulated by the spatial light modulator 123 passes through the Faraday element 131, the polarization beam splitter 133, and the Faraday element 132, is reflected by the mirror 124, and passes through the concave lens 126 that adjusts the focal point on the hologram recording medium 101. To do.

  Further, the reference light transmitted through the polarization beam splitter 113 is reflected by the mirror 141, and only the central portion of the beam is blocked by the shielding plate 142 to be formed into a desired beam shape. For this reason, it is not reflected by the mirror 124 and has the same optical path as the signal light.

  The objective lens 127 condenses the recording light and the reference light at substantially the same location on the hologram recording medium 101, so that interference fringes are formed on the hologram recording medium 101. As a result, the information spatially modulated by the spatial light modulator 123 is recorded on the hologram recording medium 101 as a hologram.

A servo signal and an address signal are output from the light receiving element 157 to the drive control system 200, and the drive control system 200 operates the servo drive unit 158 based on this servo signal, thereby eliminating tracking and focus shifts. Further, the drive control system 200 operates the optical unit 100 based on this address signal, so that the hologram can be recorded at a desired position on the hologram recording medium 101.
B. During playback

  An outline of the operation of the hologram recording / reproducing apparatus 1000 during reproduction will be described.

  During reproduction, the signal light is blocked and only the reference light is incident on the hologram recording medium 101.

  The reference light emitted from the recording / reproducing light source 111 and transmitted through the polarization beam splitter 113 is reflected by the mirror 141, and only the central portion of the beam is blocked by the shielding plate 142. Thereafter, the reference light passes through the dichroic mirror 125 and becomes reference light having a phase pattern similar to that at the time of recording by the phase modulation element 143 and enters the hologram recording medium 101.

  When reference light having the same phase pattern as that at the time of recording enters the hologram recording medium 101, diffracted light (reproduced light) is generated from the hologram recorded on the hologram recording medium 101.

  The generated reproduction light follows an optical path opposite to that of the signal light, passes through the objective lens 127, the concave lens 126, and the dichroic mirror 125, and is reflected by the mirror 124.

The direction of polarization of the reproduction light reflected by the mirror 124 is rotated by the Faraday element 132. As a result, the reproduction light emitted from the Faraday element 132 is reflected by the polarization beam splitter 133 and converted into an electrical signal corresponding to the spatial two-dimensional data in the spatial light modulator 123 by the imaging element 134. The output from the image sensor 134 is binarized by a signal processing unit (not shown) and converted into time-series binarized data.
(Example of beam spot arrangement)

  FIG. 8 shows a beam spot of red laser light irradiated on the reflective layer 108 of the hologram recording medium 101.

  As shown in FIG. 8, the three red laser beams separated by the grating 153 are irradiated to three different locations on the reflection layer 108 of the hologram recording medium 101 (beam spots 11b, 12b, 11b). .

  The interval between the beam spots 11b and 12b is equivalent to twice the interval between the tracks 10, and the beam spot 11b is deviated in the circumferential direction in the order of the beam spot 12b and the beam spot 11b.

  The beam spot 12b is used to generate a focus error signal and a tracking error signal. The beam spot 11b (one of the two 11b in FIG. 8) is used to generate an address signal.

  The example of FIG. 8 shows a state where the tracking servo is normally applied. That is, the beam spot 12 b is located in the center track groove 12 of the three track grooves 12, and the beam spot 11 b is located in the address groove 11.

As the beam spot 12b deviates from the central track groove 12, the output of the photodetector 12a (tracking error signal) becomes weaker, and the tracking servo should be applied in the direction in which the output becomes stronger. Further, when the beam spot 12b is further displaced from the central track groove 12 and positioned in the adjacent track groove 12, the beam spot 11b is positioned in the track groove 12 instead of the address groove 11, and an address signal cannot be obtained. In this case, the tracking servo may be applied so that the beam spot 12b is positioned in the center track groove 12.
(Other examples of hologram recording medium)

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the technical idea.
(1) As shown in FIG. 9, the groove 10 may have a structure in which a combination of “one address groove 11, three track grooves 12, and one clock groove 13” is repeated. In this case, the clock pattern is removed from the address groove 11 and the clock is obtained from the clock groove 13. With such a configuration, redundancy regarding the address of the address groove 11 is eliminated, and more detailed address management is possible.
(2) In the above embodiment, the three track grooves 12 are set as one set, but may be one or two.

1 is a plan view of a hologram recording medium according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view in the radial direction of the hologram recording medium shown in FIG. FIG. 3 is a schematic plan view showing a groove of the reflective layer shown in FIG. 2. It is the figure which showed the content of the information of an address groove. It is a figure which shows the detail of the information of each area | region of an address groove. It is a schematic diagram which shows the structure of a hologram recording / reproducing apparatus. It is a top view which shows the structure of the light receiving element shown in FIG. It is the plane schematic diagram which showed the beam spot of the red laser beam irradiated on the reflective layer of a hologram recording medium. It is a planar schematic diagram which shows the other example of the groove | channel of a reflection layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Groove 11 Address groove 12 Track groove 100 Optical unit 101 Hologram recording medium 102 Antireflection film layer 103 Protective layer 104 Recording layer 105 Gap layer 106 Wavelength selective reflection layer 107 Gap layer 200 Drive control system 1000 Hologram recording / reproducing apparatus

Claims (6)

A disc-shaped hologram recording medium,
A hologram recording layer on which a hologram is recorded;
A non-modulated first groove, and a second groove having a pit row modulated by address information indicating a position on the disk, and a reflective layer provided concentrically or spirally. recoding media. The hologram recording medium according to claim 1,
The hologram recording medium, wherein the reflection layer is provided with three first grooves between two adjacent second grooves. The hologram recording medium according to claim 1,
The hologram information recording medium, wherein the address information includes first information indicating a radial position on the disk and second information indicating a circumferential position on the disk. The hologram recording medium according to claim 3,
A hologram recording medium, wherein a sync pattern and a clock pattern are added to each address information. The hologram recording medium according to claim 1,
Between the hologram recording layer and the reflection layer, a laser beam having a first wavelength for irradiating the hologram recording layer is reflected, and a second wavelength for irradiating the reflection layer. A hologram recording medium comprising: a wavelength selective reflection layer through which the laser beam is transmitted. A hologram recording layer on which a hologram is recorded, and a non-modulated first groove and a reflective layer in which a second groove having a pit row modulated by address information indicating a position on the disk is provided concentrically or spirally A hologram recording and reproducing apparatus for recording and / or reproducing holograms on a disk-shaped hologram recording medium having
A first optical system for irradiating the hologram recording layer with laser light having a first wavelength and receiving the reflected light, and a wavelength that is not sensitive to the reflection layer by the hologram recording layer. And a second optical system for irradiating laser light having a wavelength of 2 and receiving the reflected light, and an objective lens for the hologram recording medium is provided with the first optical system and the second optical system. An optical unit common to the optical system,
A first drive system for rotationally driving the hologram recording medium;
A second drive system for driving the optical unit in a radial direction;
And a control means for controlling the first and second drive systems based on the address information obtained via the second optical system.

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