JP2012138148A - Apparatus and method for recording and reproducing information - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which an angle multiplex recording type holographic memory needs to change an incident angle of reference light to an optical recording medium at high speed in order to record and reproduce information at high speed, but there is a limit to the speed in a galvano mirror alone and a range capable of scanning is small in an MEMS mirror and an electro-optic crystal alone, and accordingly a sufficient number of multiplexing cannot be obtained.SOLUTION: In the apparatus and method for recording and reproducing the information, an incident angle of reference light to an optical recording medium can be controlled by combination of a mirror which controls the incident angle at low speed and has a large scanning angle range, and a mirror which controls the incident angle at high speed and has a small scanning angle range.

Description

  The present invention relates to an apparatus and method for recording or reproducing information from a recording medium.

  At present, the Blu-ray Disc (BD) standard using a blue-violet semiconductor laser has made it possible to commercialize an optical disc having a recording density of about 50 GB even for consumer use. In the future, it is desired to increase the capacity of an optical disk to the same level as an HDD (Hard Disc Drive) capacity of 100 GB to 1 TB.

  However, in order to realize such an ultra-high density with an optical disc, a high-density technology by a new method different from the high-density technology by shortening the wavelength and increasing the objective lens NA is necessary.

  While research on next-generation storage technology is underway, hologram recording technology that records digital information using holography is attracting attention.

  Hologram recording technology is a method in which signal light having page data information two-dimensionally modulated by a spatial light modulator is superimposed on reference light inside the recording medium, and the interference fringe pattern generated at that time is placed in the recording medium. This is a technique for recording information on a recording medium by causing refractive index modulation.

  At the time of reproducing information, if the recording medium is irradiated with the reference light used at the time of recording, the hologram recorded in the recording medium acts like a diffraction grating to generate diffracted light. This diffracted light is reproduced as the same light including the recorded signal light and phase information.

  The reproduced signal light is detected two-dimensionally at high speed using a photodetector such as a CMOS or CCD. As described above, the hologram recording technique enables two-dimensional information to be recorded on the optical recording medium at once by one hologram and further reproduces this information. Since the page data can be overwritten, large-capacity and high-speed information recording / reproduction can be achieved.

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

  In addition, as a technique for controlling the incident angle of the reference light in the angle multiplex recording method, for example, there is JP-A-2001-118253 (Patent Document 2). In this publication, reading light is irradiated to an optical recording medium in which signal light holding data information by spatial polarization distribution is recorded as a hologram by reference light, diffracted light is read from the hologram, and the diffracted light is detected A technique for controlling the irradiation state of the readout light onto the optical recording medium based on the detection signal and reading the data information from the diffracted light in that state is described. As a method for controlling the angle of the reference light, a method using a stepping motor, a galvanometer mirror, and an acoustooptic device is described.

JP 2004-272268 A JP 2001-118253 A

  Examples of the device that changes the beam angle include a galvanometer mirror, a polygon mirror, a MEMS mirror, an acoustooptic device, and an electro-optic crystal. A galvanometer mirror that is often used in the hologram recording technology generally has a characteristic that the angle range that can be scanned is large although it is low speed with respect to other devices. On the other hand, MEMS mirrors and electro-optic crystals are generally faster than other devices, but have a small scanable range.

  In order to perform recording and reproduction at a higher speed, it is necessary to change the incident angle of the reference light to the optical recording medium at a high speed. However, the speed of the galvanometer mirror alone is limited, and the MEMS mirror or the electro-optic crystal alone is limited. However, since the scannable range is small, there is a problem that a sufficient multiplexing number cannot be obtained.

  The object of the present invention can be solved, for example, by controlling the incidence angle of the reference light on the optical recording medium by combining a low-speed mirror with a large scanning angle range and a high-speed mirror with a small scanning angle range.

  According to the present invention, the incident angle of the reference light to the optical recording medium can be controlled at high speed.

Schematic diagram showing an embodiment of an optical information recording / reproducing apparatus Schematic showing an embodiment of a pickup in an optical information recording / reproducing apparatus Schematic showing the operation flow of angle control of reference light Schematic showing an embodiment of a pickup in an optical information recording / reproducing apparatus Schematic showing an embodiment of the operation flow of the optical information recording / reproducing apparatus Schematic showing an embodiment of a pickup in an optical information recording / reproducing apparatus Schematic showing an embodiment of a pickup in an optical information recording / reproducing apparatus Schematic showing an embodiment of a pickup in an optical information recording / reproducing apparatus

  Examples of the present invention will be described below.

  Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram showing a recording / reproducing apparatus of an optical information recording medium for recording and / or reproducing digital information using holography.

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

  The pickup 11 plays a role of emitting reference light and signal light to the optical information recording medium 1 and recording digital information on the recording medium using holography. At this time, the information signal to be recorded is sent by the controller 89 to the spatial light modulator in the pickup 11 via the signal generation circuit 86, and the signal light is modulated by the spatial light modulator.

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

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

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

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

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

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

  By the way, the recording technique using the principle of angle multiplexing of holography tends to have a very small tolerance for the deviation of the reference beam angle. Therefore, a mechanism for detecting the deviation amount of the reference beam angle is provided in the pickup 11, a servo control signal is generated by the servo signal generation circuit 83, and the deviation amount is corrected via the servo control circuit 84. It is necessary to provide a servo mechanism for this purpose in the optical information recording / reproducing apparatus 10.

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

  FIG. 2 shows a recording principle in an example of an optical system configuration of the pickup 11 in the optical information recording / reproducing apparatus 10. The light beam emitted from the light source 201 passes through the collimator lens 202 and enters the shutter 203. When the shutter 203 is open, after the light beam passes through the shutter 203, the optical element 204 composed of, for example, a half-wave plate or the like makes the light quantity ratio of P-polarized light and S-polarized light a desired ratio. After the polarization direction is controlled, the light enters a PBS (Polarization Beam Splitter) prism 205.

  The light beam that has passed through the PBS prism 205 functions as signal light 206, and after the light beam diameter is expanded by the beam expander 208, the light beam passes through the phase mask 209, the relay lens 210, and the PBS prism 211 and passes through the spatial light modulator 212. Is incident on.

  The signal light to which information is added by the spatial light modulator 212 reflects the PBS prism 211 and propagates through the relay lens 213 and the spatial filter 214. Thereafter, the light is condensed on the optical information recording medium 1 by the objective lens 215.

  On the other hand, the light beam reflected by the PBS prism 205 works as reference light 207, and is set to a predetermined polarization direction according to recording or reproduction by the polarization direction conversion element 216, and then passes through the mirror 217 to the MEMS mirror 218. Incident. The MEMS mirror 218 includes a mirror 218-a and an actuator 218-b, and the angle of the mirror 218-a can be adjusted by the actuator 218-b. The reference light reflected by the MEMS mirror 218 enters the galvanometer mirror 219. The galvanometer mirror 219 includes a mirror 219-a and an actuator 219-b, and the angle of the mirror 219-a can be adjusted by the actuator 219-b. The reference light reflected by the galvanometer mirror 219 enters the optical information recording medium 1 after passing through the lens 221 and the lens 222. By using the two angle control elements of the MEMS mirror 218 and the galvanometer mirror 219, the incident angle of the reference light incident on the optical information recording medium 1 can be set to a desired angle within a high speed and large scanning angle range.

  In this way, the signal light and the reference light are incident on the optical information recording medium 1 so as to overlap each other, whereby an interference fringe pattern is formed in the recording medium, and information is recorded by writing this pattern on the recording medium. To do. In addition, since the incident angle of the reference light incident on the optical information recording medium 1 can be changed by the MEMS mirror 218 and the galvanometer mirror 219, recording by angle multiplexing is possible.

  In FIG. 2, the MEMS mirror having a small angle scanning range is arranged ahead of the galvanometer mirror having a large angle scanning range in the direction in which the reference light travels. This is to prevent the mirror disposed later from becoming large by reducing the range in which the reference light moves on the mirror disposed later by angle scanning of the mirror disposed earlier. And the arrangement order of the galvanometer mirrors may be reversed.

  In FIG. 2, the MEMS mirror and the galvanometer mirror are separately arranged. However, if the MEMS mirror can be made as small and lightweight as the mirror portion 219-a of the galvanometer mirror 219, Instead, a fixed mirror may be disposed, and the mirror portion 219-a of the galvano mirror 219 may be configured with a MEMS mirror. In this case, the angle is largely controlled in the entire mirror part of the galvano mirror 219, and further, the MEMS mirror controls a small angle in this mirror part.

  Hereinafter, in holograms recorded in the same area with different reference beam angles, holograms corresponding to each reference beam angle are called pages, and a set of pages angle-multiplexed in the same area is called a book. .

Here, an operation flow of control combining the MEMS mirror 218 and the galvanometer mirror 219 will be described with reference to FIG. The angle controlled by the galvanometer mirror is θ, and the angle controlled by the MEMS mirror is φ. The angular interval of the angular multiplexing as [Delta] [phi, phi is a variable from the initial value phi ₀ m of multi-component φ _{0 +} (m-1) to [Delta] [phi. Further, assuming that (m−1) Δφ in the angular range that can be scanned by the MEMS mirror is Δθ, θ is variable from an initial value θ ₀ to θ ₀ + (n−1) Δθ for m × n multiples. Here, m and n are integers.

When book recording starts, first, the angle of the galvanometer mirror is set to the initial value θ ₀ and drive control is performed (S301). Next, the angle of the MEMS mirror is set to an initial value and drive control is performed (S302). After the galvano mirror and the MEMS mirror are set to a desired angle, the page is recorded (S303). If the angle of the MEMS mirror is within the variable range (S304), the angle of the MEMS mirror is increased by Δφ (S305), and the page is recorded again. If the angle of the MEMS mirror is not less than the variable range, it is determined whether the angle of the galvanometer mirror is within the variable range (S306). If the angle of the galvanometer mirror is within the variable range, the angle of the galvanometer mirror is increased by Δθ (S307), and the page is recorded again. If the angle of the galvanometer mirror is greater than or equal to the variable range, the book recording is terminated. In the above description, the operation at the time of recording has been described.

If the time for driving and setting the angle of Δφ with the MEMS mirror is t, and the time for driving and setting the angle of Δθ with the galvano mirror is T _θ , the time required for driving the mirror in the book is mt + nT _θ .

As an example, the angle of incidence of the reference light on the optical information recording medium is recorded with 301 multiplexing at intervals of Δφ = 0.1 degree from the initial value φ ₀ = 25 degrees to 55 degrees with respect to the normal of the optical information recording medium. Think about the case. Since the MEMS mirror can be driven at 60 kHz, t = 15 μs is estimated. If the angular scanning range of the MEMS mirror is about 10 degrees, the multiplexing number m by the MEMS mirror must be 100 and the multiplexing number n by the galvanometer mirror must be 3 in order to obtain an angular scanning range of 30 degrees to 30 degrees. There is. The time T _θ = 1 ms for scanning the galvanometer mirror 10 degrees is estimated. Numerical above estimates, the time to drive the mirror in a book is a _{mt + nT θ = 100 × 15μs} + 3 × 1ms = 4.5ms. Note that the galvanometer mirror can sufficiently scan an angle of about 40 degrees.

Next, a case where all angle control is performed using only a galvanometer mirror without using a MEMS mirror will be considered. When the time for driving and setting the angle of Δφ with the galvano mirror is T _φ , the time required for driving the mirror in the book is mnT _φ (= mT _φ + nT _φ ). Since MEMS mirrors are faster than galvanometer mirror, a t <T _phi, and because the time to Δφ drive T _phi and time for Δθ driven T _theta galvanometer mirror, which does not significantly change, the MEMS mirror and galvanometer mirror It can be seen that the combined control is faster than the case of controlling only with the galvanometer mirror.

As an example, when the T _phi = 300 [mu] s, the time to drive the mirror in a book is a _{mnT φ = 100 × 3 × 300μs} = 9ms.

  In FIG. 3, the galvano mirror and the MEMS mirror are described as an operation that repeats driving and stationary. However, the MEMS mirror is angled so that the reference light angle is relatively stationary while the galvano mirror is continuously changed in angle. You can change it. In FIG. 3, the angle intervals Δφ and Δθ are described as being fixed, but may be variable.

  FIG. 4 shows the principle of reproduction in an example of the optical system configuration of the pickup 11 in the optical information recording / reproducing apparatus 10. When reproducing the recorded information, as described above, the reference beam is incident on the optical information recording medium 1, the light beam transmitted through the optical information recording medium 1 is condensed by the lens 223, and the optical axis is focused on the condensing point. The phase conjugate light is generated by being reflected by a mirror 224 arranged vertically.

  The signal light reproduced by the phase conjugate light propagates through the objective lens 215, the relay lens 213, and the spatial filter 214. Thereafter, the signal light passes through the PBS prism 211 and enters the photodetector 225, and the recorded signal can be reproduced. The photodetector 225 can be configured using an image sensor represented by a CCD or a CMOS.

  In addition, since the point focused by the lens 223 may not be fixed on one surface due to lens aberration or disturbance, the mirror 224 is adaptively controlled in the optical axis direction and always reflected near the focused point. By doing so, it is possible to keep the parallelism of the phase conjugate light more suitable.

  FIG. 5 shows an operation flow of recording and reproduction in the optical information recording / reproducing apparatus 10. Here, a flow relating to recording / reproduction using holography in particular will be described.

  FIG. 5A shows an operation flow from when the optical information recording medium 1 is inserted into the optical information recording / reproducing apparatus 10 until preparation for recording or reproduction is completed, and FIG. FIG. 5C shows an operation flow until information is recorded on the information recording medium 1, and FIG. 5C shows an operation flow until the information recorded on the optical information recording medium 1 is reproduced from the ready state.

  When a medium is inserted as shown in FIG. 5A (S501), the optical information recording / reproducing apparatus 10 discriminates whether or not the inserted medium is a medium for recording or reproducing digital information using holography, for example. (S502).

  As a result of disc discrimination, when it is determined that the optical information recording medium records or reproduces digital information using holography, the optical information recording / reproducing apparatus 10 reads control data provided on the optical information recording medium (S503). ), For example, information relating to the optical information recording medium and information relating to various setting conditions during recording and reproduction, for example.

  After reading out the control data, various adjustments according to the control data and learning processing related to the pickup 11 (S504) are performed, and the optical information recording / reproducing apparatus 10 is ready for recording or reproduction (S505).

  As shown in FIG. 5B, the operation flow from the ready state to recording information is as follows. First, data to be recorded is received (S511), and information corresponding to the data is received from the spatial light modulator in the pickup 11. To send.

  After that, various learning processes are performed in advance so that high-quality information can be recorded on the optical information recording medium (S512), and the positions of the pickup 11 and the disk Cure optical system 13 are optically determined by a seek operation (S513). The information recording medium is arranged at a predetermined position.

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

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

  As shown in FIG. 4C, the operation flow from the ready state to the reproduction of the recorded information is performed in advance with various learning processes as necessary so that high-quality information can be reproduced from the optical information recording medium. To do. Thereafter, the positions of the pickup 11 and the phase conjugate optical system 12 are arranged at predetermined positions on the optical information recording medium while repeating the seek operation and the address reproduction.

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

  The present invention is applied in the data recording operation of S515 or the data reproducing operation of S523.

  FIG. 6 shows another optical system configuration example of the phase conjugate system. FIG. 6 shows the principle of reproduction in an example of the optical system configuration of the pickup 11 in the optical information recording / reproducing apparatus 10. The lens 226 is arranged between the lens 223 and the mirror 224 in FIG. In addition, the lens 226 is disposed at a position away from the lens 223 by the focal length of the lens 226 from the mirror position in FIG. 4, and the mirror 224 is disposed at a position further away from the position of the lens 226 by the focal length of the lens 226. It is preferable to do.

  In the case of this configuration, the reference light that has passed through the optical information recording medium 1 passes through the lens 223 and the lens 224, is reflected by the mirror 224, passes through the lens 223 and the lens 224 again, and enters the optical information recording medium 1. Incident. The reference light that has passed through the optical information recording medium 1 and the reference light that has entered the optical information recording medium 1 after being reflected by the mirror 224 have a symmetrical angle with respect to the optical axes of the lens 223 and the lens 226. For this reason, the angle control positions of the MEMS mirror 218 and the galvanometer mirror 219 are different from those at the time of recording, but can be calculated in advance, so that this is not a problem.

  In the optical system configuration of FIG. 4, when the reference light angle changes, the focal position may be shifted due to the aberration of the lens 223. When the focal position is deviated, the reference light reflected by the mirror 224 is not converted into parallel light by the lens 223, and there is a possibility that the reproduction quality is deteriorated. However, the optical system configuration of FIG. 6 has an advantage that the aberration is canceled by the lens 223 and the lens 226, and thus there is an advantage that it is easy to ensure reproduction quality.

  FIG. 7 shows another optical system configuration in the angle control of the MEMS mirror and the galvanometer mirror. FIG. 7 shows a recording principle in an example of the optical system configuration of the pickup 11 in the optical information recording / reproducing apparatus 10. A lens 227 and a lens 228 are arranged between the MEMS mirror 218 and the galvanometer mirror 219 in FIG. It has become the composition. In the case of the optical system configuration of FIG. 2, the optical axis shift occurs in principle because the reference mirror angle is changed by the MEMS mirror 218. However, in this embodiment, the optical axis shift does not occur between the lens 227 and the lens 228. There are advantages.

FIG. 8 shows an optical system configuration using an electro-optic crystal instead of the MEMS mirror. FIG. 8 shows a recording principle in an example of the optical system configuration of the pickup 11 in the optical information recording / reproducing apparatus 10. A mirror 229 is arranged instead of the MEMS mirror 218 in FIG. 2, and the mirror 229 and the galvano mirror 219 are arranged. The electro-optic crystal 230 is disposed between the two. An electro-optic crystal is a device capable of scanning an angle of a beam at a high speed by applying a voltage. As an example, the electro _- optic crystal can be manufactured using a KTa _1-x Nb _x O ₃ (KTN) crystal. Since the electro-optic crystal KTN has been reported to operate at 400 kHz or higher, there is an advantage that the speed can be further increased as compared with the case where the MEMS mirror is used.

  As described above, as an example of a device that performs angle control in combination with a galvanometer mirror, description has been made using a MEMS mirror or an electro-optic crystal, but a device that exhibits the same effect, such as a polygon mirror, may be used. You may comprise so that a scanning angle may be taken large by combining a MEMS mirror and a MEMS mirror.

In the above configuration, the optical system for generating the phase conjugate light is arranged after the reference light is transmitted through the optical information recording medium 1. However, for example, the light as described in JP 2009-103765 A A configuration may be employed in which phase conjugate light is generated by forming a diffraction grating on the reflection surface of the information recording medium 1.

DESCRIPTION OF SYMBOLS 1 ... Optical information recording medium, 10 ... Optical information recording / reproducing apparatus, 11 ... Pickup,
12 ... Phase conjugate optical system, 13 ... Disc Cure optical system,
14 ... Optical system for detecting the disk rotation angle, 50 ... Rotation motor,
81 ... Access control circuit, 82 ... Light source driving circuit, 83 ... Servo signal generation circuit,
84 ... Servo control circuit, 85 ... Signal processing circuit, 86 ... Signal generation circuit,
87 ... Shutter control circuit, 88 ... Disc rotation motor control circuit,
89 ... Controller,
201 ... light source, 202 ... collimating lens, 203 ... shutter,
204 ... 1/2 wavelength plate, 205 ... polarizing beam splitter,
206: Signal light, 207: Reference light,
208... Beam expander, 209 .. Phase mask,
210 ... relay lens, 211 ... polarizing beam splitter,
212 ... Spatial light modulator, 213 ... Relay lens, 214 ... Spatial filter,
215 ... Objective lens, 216 ... Polarization direction conversion element, 217 ... Mirror,
218 ... MEMS mirror, 219 ... Galvano mirror,
221 ... lens, 222 ... lens, 223 ... actuator,
224 ... mirror, 225 ... photodetector, 226 ... lens,
227 ... lens, 228 ... lens, 229 ... mirror, 230 ... electro-optic crystal

Claims (7)

An information recording / reproducing apparatus for recording information on a hologram recording medium as page data of an interference pattern, or reproducing information from a hologram recording medium on which the interference pattern is recorded as page data,
A laser light source for emitting laser light;
An optical element for separating the laser light into reference light and signal light;
A first angle adjusting unit for adjusting an incident angle of the separated reference light to the recording medium;
A second angle adjusting unit for adjusting an incident angle of the separated reference light to the recording medium,
An information recording / reproducing apparatus, wherein information is recorded or reproduced by irradiating a hologram recording medium with reference light adjusted by the first angle adjusting unit and the second angle adjusting unit. The information recording / reproducing apparatus according to claim 1,
The scanning speed of the first angle adjustment unit is higher than the scanning speed of the second angle adjustment unit,
An information recording / reproducing apparatus, wherein a scanning angle range of the first angle adjusting unit is smaller than a scanning angle range of the second angle adjusting unit. An information recording / reproducing apparatus according to claim 2,
2. The information recording / reproducing apparatus according to claim 1, wherein the separated reference light is incident on the first angle adjusting unit and then incident on the second angle adjusting unit. An information recording / reproducing apparatus according to claim 3,
The first angle adjustment unit is composed of a MEMS mirror,
The information recording / reproducing apparatus according to claim 2, wherein the second angle adjusting unit is configured by a galvanometer mirror. An information recording / reproducing apparatus according to claim 3,
The first angle adjusting unit is composed of an electro-optic crystal;
The information recording / reproducing apparatus according to claim 2, wherein the second angle adjusting unit is configured by a galvanometer mirror. An information recording or reproducing method for recording as interference pattern page data on a hologram recording medium, or reproducing information from a hologram recording medium in which an interference pattern is recorded as page data,
Emits laser light,
Separating the laser light into reference light and signal light;
Adjusting the incident angle of the separated reference light to the recording medium with a first angle adjusting unit;
Adjusting the incident angle of the reference light adjusted by the first angle adjusting unit to the recording medium by the second angle adjusting unit;
A method of recording or reproducing information, wherein information is recorded or reproduced by irradiating a hologram recording medium with reference light adjusted by the first angle adjusting unit and the second angle adjusting unit. An apparatus for scanning the angle of a light beam,
An apparatus comprising an angle adjusting unit for at least two light beams.

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