JP2008203772A - Hologram recording or reproducing device, and hologram recording or reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique where, in hologram recording/reproducing using a spacial optical modulator, the influence of the fluctuation in the wavelength of a light source is reduced. <P>SOLUTION: In the hologram recording/reproducing device 10 where signal light 19 and reference light 20 obtained by introducing a light beam 16 from a laser light source 11 into a spacial optical modulator 17, and subjecting the same to spacial modulation are emitted to a hologram medium 22, and recording data are recorded/reproduced as a hologram, the wavelength of a light beam from the laser light source 11 is detected, and, in accordance with the wavelength of the light beam, the relative angle between the spacial optical modulator 17 and the light beam 16 made incident on the spacial optical modulator is changed, thus the emission angle between the signal light 19 and the reference light 20 emitted from the spacial optical modulator 17 is controlled to a prescribed direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

In recent years, hologram memories have attracted attention as storage devices that perform high-density recording and reproduction (see, for example, Patent Document 1). In this hologram memory, a light beam is modulated using a spatial light modulator (SLM) to obtain signal light and reference light. In the spatial light modulator, four parameters of the wavelength of the incident light beam, the incident angle / exit angle, and the pixel pitch are related to each other according to the Bragg condition. Further, in the case of the reflective SLM, The parameters of the pixel reflection surface angle are also weighted and related to each other, and the emission angle is uniquely determined with respect to conditions such as the wavelength of the incident light beam. Here, suitable devices that can be used as the reflective SLM include, for example, DMD (Digital Micromirror Device), GLV (registered trademark), Grafting Light Valve, and MicroSM (μSLM). (See Non-Patent Document 1).
JP 2006-349831 A Katsumi Oishi, Akira Tomita, “Using Optical Diffraction Phenomena to Reduce Variations in Optical Power of DWDM Communication,” Design Wave Magazine, November 2002, p. 86-87.

  For this reason, in the hologram recording / reproducing apparatus using the spatial light modulator, the emission angle of the light beam (modulated light beam) modulated by the spatial light modulator changes due to the fluctuation of the wavelength of the light beam from the laser light source. . In this case, the beam irradiation position on the medium is shifted, and the quality of the recording or / and reproduction signal (recording / reproducing signal) is deteriorated. In addition, when a variable wavelength light source is introduced into the hologram recording / reproducing apparatus and the wavelength is intentionally controlled to perform multiplex recording or / and reproduction (multiplex recording / reproduction), recording or / and reproduction conditions (for the same reason) There is a problem that deterioration of recording / reproducing conditions occurs.

  An object of the present invention is to solve such problems and to provide a technique for reducing the influence of fluctuation of the wavelength of a light source in hologram recording and / or reproduction (hologram recording / reproduction) using a spatial light modulator. .

  The hologram recording or reproducing apparatus of the present invention records a recording data as a hologram by directing a light beam from a laser light source to a spatial light modulator and irradiating the modulated light beam subjected to spatial modulation to the hologram medium, or In a hologram recording or reproducing apparatus for reproducing the recorded data by irradiating the hologram recorded on the hologram medium with the modulated light beam, the wavelength of the light beam from the laser light source is detected, and the wavelength of the light beam is changed to Accordingly, the relative angle between the spatial light modulator and the light beam incident on the spatial light modulator is changed, and the emission angle of the modulated light beam emitted from the spatial light modulator is set to a predetermined direction. To do.

  In the hologram recording or reproducing method of the present invention, a light beam from a laser light source is guided to a spatial light modulator to irradiate the hologram medium with a modulated light beam subjected to spatial modulation, and recording data is recorded as a hologram, or Irradiating the hologram recorded on the hologram medium with the modulated light beam to reproduce the recorded data. In the method of recording or reproducing a hologram, the wavelength of the light beam from the laser light source is detected, and the light beam The relative angle between the spatial light modulator and the light beam incident on the spatial light modulator is changed in accordance with the wavelength of the spatial light modulator, and the emission angle of the modulated light beam emitted from the spatial light modulator is predetermined. It is a direction.

  In this hologram recording or reproducing apparatus and hologram recording or reproducing method, the wavelength of a light beam from a laser light source is detected. Then, the relative angle between the spatial light modulator and the light beam incident on the spatial light modulator is changed according to the wavelength of the light beam. In this way, the emission angle of the modulated light beam emitted from the spatial light modulator is set to a predetermined direction.

  In another hologram recording or reproducing apparatus of the present invention, a recording medium is recorded as a hologram by directing a light beam from a laser light source to a spatial light modulator and irradiating the modulated light beam subjected to spatial modulation onto the hologram medium. Or, in the hologram recording device or the hologram reproducing device, which reproduces the recorded data by irradiating the hologram recorded on the hologram medium with the modulated light beam, the wavelength of the light beam from the laser light source is detected, The pixel reflection surface depth of the diffraction grating of the spatial light modulator is controlled according to the wavelength of the light beam, and the emission angle of the modulated light beam emitted from the spatial light modulator is set to a predetermined direction.

  In another hologram recording or reproducing method of the present invention, a recording medium is recorded as a hologram by irradiating a hologram medium with a modulated light beam subjected to spatial modulation by guiding a light beam from a laser light source to a spatial light modulator. Or a hologram recording or reproducing method for reproducing the recording data by irradiating the hologram recorded on the hologram medium with the modulated light beam, and detecting the wavelength of the light beam from the laser light source, The pixel reflection surface depth of the diffraction grating of the spatial light modulator is controlled according to the wavelength of the spatial light modulator, and the emission angle of the modulated light beam emitted from the spatial light modulator is set to a predetermined direction.

  In this other hologram recording or reproducing apparatus and hologram recording or reproducing method, the wavelength of the light beam from the laser light source is detected. Then, the pixel reflection surface depth of the diffraction grating of the spatial light modulator is controlled according to the wavelength of the light beam. In this way, the emission angle of the modulated light beam emitted from the spatial light modulator is set to a predetermined direction.

  According to the present invention, even when the wavelength of the incident light beam incident on the spatial light modulator changes, the emission angle of the modulated light beam from the spatial light modulator is made constant, which A technology for improving signal quality can be provided.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments that are the best mode of the present invention will be described below with reference to the drawings.

  FIG. 1 schematically shows a hologram recording / reproducing apparatus 10 according to the embodiment centering on a main part of the embodiment. A hologram recording / reproducing apparatus 10 shown in FIG. 1 is a hologram recording / reproducing apparatus called a coaxial system. The light beam emitted from the laser light source 11 passes through the collimating lens 12 and is reflected by the mirror 13 and the mirror 14. Here, the mirror 14 is rotated by the angle adjusting mechanism 15 (first angle adjusting mechanism) about a support shaft extending in the front and back direction of the paper surface orthogonal to the paper surface, and the reflection angle is adjusted within the paper surface. With this angle adjustment mechanism 15, the incident angle of the incident light beam 16 to the spatial light modulator 17 can be adjusted.

  In the spatial light modulator 17, minute reflection mirrors whose inclination angle can be controlled depending on the amount of applied voltage are arranged in an array. Each mirror constituting this array corresponds to one intensity modulation pixel. By controlling the tilt angle of the mirror individually, the ON / OFF of the light for each pixel is controlled by controlling the establishment / non-establishment of the diffraction condition described later for each pixel. As examples of the spatial light modulator 17 having such a configuration, there are DMD (Digital Micromirror Device), GLV (registered trademark), Grafting Light Valve, and MicroSL (μSLM). These simple explanations are given in Non-Patent Document 1 described above.

  The spatial light modulator 17 is provided with an angle adjustment mechanism 18 (second angle adjustment mechanism) for adjusting the reflection angle (diffraction angle) in a plane parallel to the paper surface. The angle of the light receiving surface of the optical modulator 17 can be adjusted. That is, the spatial light modulator 17 is rotated by the angle adjusting mechanism 18 about a support shaft extending in the front and back direction of the paper surface orthogonal to the paper surface.

  In the spatial light modulator 17, a light beam (modulated light beam), which is divided into signal light 19 and reference light 20 and subjected to intensity modulation, is condensed in the hologram medium 22 by the objective lens 21 and intersects. Thus, an interference fringe called a hologram is formed.

  Next, reproduction in this method will be described. The light beam exits the laser light source 11, passes through the collimating lens 12, and the incident light beam 16 reflected by the mirror 13 and the mirror 14 enters the spatial light modulator 17. In the case of reproduction, the area of the signal light 19 is zero, and only the reference light 20 is modulated in the same pattern as that during recording. The light beam (modulated light beam) obtained by modulating only the reference light 20 passes through the objective lens 21 and is collected on the hologram in the hologram medium 22. The diffracted light of the reference light 20 in the hologram in the hologram medium 22 forms an image on the imaging surface of the array-type photodetector 24 as a light intensity pattern of the reproduction hologram by the condenser lens 23. As the array-type photodetector 24, an image sensor such as a CSD (CCD) sensor or a CMOS (CMOS) sensor is used.

  FIG. 2 is a diagram for explaining diffraction conditions when a DMD (DMD) is used as an example of the spatial light modulator 17.

  First, referring to FIG. 2, the angle deviation of the outgoing light beam (outgoing light beam) with respect to the wavelength change of the light beam incident on the spatial light modulator 17, and the reflection of the angle adjusting mechanism 18 for correcting the deviation. A relationship with the correction amount of the surface angle will be described.

  Here, the wavelength of the incident light beam 16 is λ, the incident angle is θin, the pixel pitch of the spatial light modulator 17 is d, the signal light 19 which is a modulated light beam obtained as diffracted light by the spatial light modulator 17 and the reference The emission angle of the light 20 is θout at the time of recording, or the emission angle of the reference light 20 is θout at the time of reproduction recording. Equation (1) is obtained from the Bragg condition.

  sin θin + sin θout = mλ / d (1)

  Between the incident angle / outgoing angle and the reflecting surface angle φ, the relationship represented by Expression (2) is established.

  θin = 2φ−θout (2)

  Expression (3) is obtained from Expression (1) and Expression (2).

  sin θout + sin (2φ−θout) = mλ / d (3)

  Furthermore, in order for the emission angle θout to be in the normal direction of the spatial light modulator, equation (4) is obtained from equation (2).

  θout = 2φ−θin = 0 (4)

  Therefore, Expression (5) can be obtained from Expression (3) and Expression (4).

  sin θin = mλ / d (5)

  Here, when the wavelength λ of the incident light beam changes to λ + δλ, the emission angle change δθout of the modulated light beam is expressed by the equation (6) from the equation (3). However, the value of m in Equation (3) is m = + 1, that is, the diffraction order is +1.

   δθout = δλ / d / (cos θout−cos (2φ−θout)) (6)

  At this time, if the reflection surface angle correction amount is δφ, Expression (7) is obtained from Expression (2).

θin = 2 (φ + δφ) − (θout + δθout)
= 2θ−θout + 2δφ−δθout (7)

  Therefore, in order to correct the emission angle change δθout under the condition that the incident angle θin is constant, the condition shown by the equation (8) is required.

2δφ -δθout = 0
δφ = δθout / 2 (8)

  Then, Expression (9) is obtained from Expression (6) and Expression (8).

   δφ = δλ / 2d / (cos θout−cos (2φ−θout)) (9)

  That is, if the angle correction amount δφ expressed by the equation (9) is applied to the reflection surface angle of the spatial light modulator 17 with respect to the wavelength change δλ, the signal light 19 and the reference light 20 or the reference light 20 that are the modulated light beams. This makes it possible to make the emission angle θout constant. Here, the change of the reflection surface angle of the spatial light modulator 17 is given by the angle adjusting mechanism 18.

  Next, using FIG. 2 again, the angle adjustment mechanism 15 for correcting the angle deviation of the emitted light beam (emitted light beam) with respect to the wavelength change of the light beam incident on the spatial light modulator 17 and correcting the deviation. The relationship with the correction amount of the reflection surface angle will be described.

  Expression (10) is an expression showing the relationship between the incident angle / exit angle and the reflecting surface angle φ.

  θout = 2φ−θin (10)

  Expression (11) can be obtained from Expression (10) and Expression (1).

   sin θin + sin (2φ−θin) = mλ / d (11)

  Here, when the wavelength λ is the wavelength λ + δλ, the incident angle change δθin can be obtained as the equation (12) from the differentiation of both sides of the equation (11).

δθin = δλ / d / (cosθin−cosθout)
= Δλ / d / (cos (2φ−θout) −cosθout) (12)

  That is, if the angle correction amount δφ expressed by the equation (12) is applied to the reflection surface angle of the mirror 14 with respect to the wavelength change δλ, the emission angle of the signal light 19 and the reference light 20 or the reference light 20 that are the modulated light beams. θout can be made constant. Here, the change in the reflection surface angle of the mirror 14 is given by the angle adjusting mechanism 15 as described above.

  As described above, in order to make the emission angle θout of the signal light 19 and the reference light 20 or the reference light 20 that are modulated light beams constant with respect to the wavelength change δλ, the angle adjusting mechanism 18 may be adjusted. It can be seen that the angle adjusting mechanism 15 may be adjusted. In other words, the relative angle between the spatial light modulator 17 and the incident light beam incident on the spatial light modulator 17 can be appropriately adjusted to make the emission angle θout of the modulated light beam constant.

  Such control is performed around the control unit 27.

  When the control unit 27 adjusts the angle adjustment mechanism 18 to appropriately adjust the emission angle of the outgoing light beam, the following procedure is performed.

  First, the control unit 27 detects the wavelength of the emitted light beam from the laser light source 11 by a wavelength monitor built in the laser light source 11.

  Next, the control unit 27 obtains the angle correction amount δφ by the equation (9), and gives the angle correction amount δφ as the change amount of the reflection surface angle of the spatial light modulator 17 by the angle adjustment mechanism 18.

  On the other hand, when the control unit 27 appropriately adjusts the emission angle of the outgoing light beam by adjusting the angle adjustment mechanism 15, the following procedure is performed.

  First, the control unit 27 detects the wavelength of the emitted light beam from the laser light source 11 by a wavelength monitor built in the laser light source 11.

  Next, the control unit 27 obtains the angle correction amount δφ by Expression (12), and gives the angle correction amount δφ as a change amount of the reflection surface angle of the mirror 14 by the angle adjustment mechanism 15.

  Here, when the wavelength of the light beam from the laser light source 11 is changed, the laser light source 11 is expected to operate as a fixed wavelength light source, but the wavelength fluctuation occurs. Is a wavelength tunable light source. For example, the recording / reproducing characteristics may be improved by changing the wavelength. In either case, the signal light 19 and the reference light 20 or the reference light 20 are obtained by the above-described method. The emission angle θout can be made constant.

  Although the laser light source 11 includes a wavelength monitor that detects the wavelength of the light beam, the wavelength monitor may be provided separately from the laser light source 11.

  A specific application example in the case where the signal light 19 and the reference light 20 or the emission angle θout of the reference light 20 are constant as described above will be described.

  First, assuming that the laser light source 11 is a fixed wavelength light source, the effectiveness of the above-described method will be described in the case where wavelength fluctuation occurs during reproduction. In this case, the emission angle of the modulation signal from the spatial light modulator 17 is shifted, and this shift becomes a beam irradiation position shift on the hologram medium 22, so that a sufficient light intensity of the reproduction signal cannot be obtained. Become.

  In this case, the wavelength of the light beam used at the time of recording the hologram is detected by a wavelength monitor, and the difference from the wavelength of the light beam detected by the wavelength monitor at the time of reproduction is taken to obtain a reflection surface represented by equation (9) By calculating the angle correction amount and applying a drive voltage corresponding to the angle correction amount to the angle adjustment mechanism 18, it is possible to correct the angle shift of the modulated light beam accompanying the wavelength shift. Alternatively, the correction amount of the angle of the modulated light beam due to the wavelength shift can be corrected by calculating the correction amount of the reflection surface angle represented by Expression (12) and applying a drive voltage corresponding to the angle correction amount to the angle adjustment mechanism 15. Can be performed.

  Next, assuming that the laser light source 11 is a wavelength tunable light source, an application example of the above method will be described in the case where a plurality of holograms are overwritten by wavelength multiplexing while changing the wavelength.

  In this case as well, the basic angle adjustment method is the same as in the above case. The wavelength of the light beam emitted from the laser light source 11 configured as a wavelength variable light source capable of emitting a plurality of predetermined different wavelengths is sequentially adjusted, and at the same time, from the amount of wavelength change from the reference wavelength. Then, a drive voltage corresponding to the reflection surface angle correction amount calculated by the equation (9) is applied to the angle adjustment mechanism 18, and holograms are sequentially recorded. In the subsequent reproduction operation, the same wavelength as the recording wavelength for each hologram is set as the wavelength of the reproduction light, and the same wavelength compensation procedure as that at the time of recording is executed, and the reflection surface angle correction amount calculated by Expression (9) A drive voltage corresponding to the above is applied to the angle adjusting mechanism 18 to sequentially reproduce the holograms.

  As another angle adjustment method, the wavelength of the light beam emitted from the laser light source 11 configured as a wavelength variable light source capable of emitting a plurality of different predetermined wavelengths is sequentially adjusted, and at the same time, From the wavelength change amount from the reference wavelength, a drive voltage corresponding to the reflection surface angle correction amount calculated by the equation (12) is applied to the angle adjustment mechanism 15 to sequentially record the holograms, and the subsequent reproduction operation , The same wavelength as the recording wavelength for each hologram is set as the wavelength of the reproduction light, the same wavelength compensation procedure as that at the time of recording is executed, and the driving voltage corresponding to the reflection surface angle correction amount calculated by Expression (12) May be applied to the angle adjustment mechanism 15 to sequentially reproduce the hologram.

  Here, for example, in the case where DMD (DMD) is used as the spatial light modulator 17, an example of the result represented by Expression (12) is shown.

The amount of change in the incident angle θin for correcting the wavelength change of 1 nm is as follows.
Assuming that δλ = 1 nm, d = 13.68 μm, φ = 12 deg, θout = 0 deg,

δθin = 1 / (13.68 × 10 ^ 3) / (cos (2 × 12) −cos (0))
= 8.455 × 10 ^ (− 4) deg (13)

The DMD employed in the present embodiment is a product of Texas Instruments Inc. of the United States, and the optical of the coaxial hologram recording / reproducing apparatus described in the present embodiment is described using Equation (9) based on its physical specifications. A typical specification has the following characteristics.
Wavelength control range 402.54 to 408.06 [nm] (δλ = 5.52 [nm])
Wavelength resolution about 0.02 [nm]
Adjustment angle range δφ = 0.009233 [deg]

  FIG. 3 shows the effect when the wavelength compensation method of this embodiment is applied as an experimental example. Each of FIGS. 3A and 3B is a diagram showing a reproduced image on the light receiving surface of the array-type photodetector 24. A deviation of the emission angle of the modulated light beam from the spatial light modulator 17 due to the wavelength deviation, and a reproduction signal deteriorated due to a deviation of the incident angle of the reproduction light with respect to the hologram medium (see FIG. 3A) and this embodiment This is compared with a reproduction signal (see FIG. 3B) when wavelength shift compensation is performed by the technique of the embodiment. In the case where the wavelength shift compensation shown in FIG. 3A is not performed, the symbol error rate per page is 20.9%. The symbol error rate was improved to 0.735%. In obtaining the reproduced image shown in FIG. 3B, a method of controlling the angle adjustment mechanism 15 was adopted.

  The case where GL (GLV) or MicroSL (μSLM) is used as the spatial light modulator 17 will be described.

  MicroSLMM, which modulates each pixel by deflecting a thin-film hinge with a reflecting surface with an electrostatic force, enables analog drive by voltage control. In this case, the expression corresponding to Expression (9) can be expressed not by the angle change (δφ) but by the hinge depth change (δz). That is, the wavelength dependency of the emission angle of the modulated light beam can be suppressed by controlling the pixel reflection surface depth of the diffraction grating in accordance with the wavelength change of the incident light.

  FIG. 4 is a diagram for explaining diffraction conditions in the case where GLV (GLV) is used as the spatial light modulator.

  Referring to FIG. 4, the relationship of hinge depth change δz with respect to wavelength change δλ is determined, where θin is the incident angle of the light beam, θout is the outgoing angle of the light beam, and z is the hinge depth. The optical path difference A on the incident side and the optical path difference B on the exit side are expressed by Expression (14).

A = (d−z × sin θin / cos θin) × sin θin + z / cos θin (14)
B = (z−d × tan θout) × cos θin (15)

  Here, when θin = θout and the Bragg conditions are arranged, Expression (16) is obtained.

   mλ = A + B = 2z × cos θ (16)

Finally, equation (17) is obtained. Here, assuming that the first-order diffracted light is m = 1, δλ = δz × 2 cos θ (17)

  In Expression (17), the emission angle θout can be made constant by changing the depth change δz of the hinge with respect to the wavelength change δλ.

  For example, in the case of GLV (GLV), when the pixel pitch d = 24.8 μm, the hinge depth z can be continuously controlled up to a maximum of 400 nm. Accordingly, when the incident angle θin = the outgoing angle θout = 12 deg, the hinge depth change δz for correcting the wavelength change δλ = 1 nm is expressed by the equation (18) from the equation (17).

   δz = δλ / 2 / cos θ = 1/2 / cos (12) = 0.511 [nm] (18)

It should be noted that the depth change of the hinge is as follows: δλ = 5.52 nm, d = 24.8 μm, θout = θin = 12 deg using Equation (17) from the physical specifications of GLV (GLV) adopted in the present embodiment. Deriving the range of δz has the following characteristics.
Depth change of hinge δz = 2.821 nm

  FIG. 5 schematically shows a main part of the hologram recording / reproducing apparatus 30 in the case where a spatial light modulator represented by GL (GLV) is used. In this case, in the embodiment shown in FIG. 1, the spatial light modulator 17 and the angle adjustment mechanism 18 are used as a configuration in which the entire spatial light modulator is rotated by another angle adjustment mechanism. Such a complex structure is not required. When GLV (GLV) is used, a control signal (analog drive voltage) corresponding to the wavelength change of incident light is directly supplied from the control unit 27 to GLV (GLV) functioning as the spatial light modulator 117, and diffraction is performed. By controlling the depth of the pixel reflection surface of the grating, the wavelength dependence of the emission angle of the modulated light beam can be suppressed.

  Further, in the hologram recording / reproducing apparatus 30 shown in FIG. 5, GL (GLV) is controlled by a predetermined binary control signal (digital drive voltage), and by a control signal corresponding to the wavelength change of incident light. The angle adjustment mechanism 15 can be adjusted to suppress the wavelength dependency of the emission angle of the modulated light beam.

  As is clear from the above-described embodiment, the technique of the present invention can suppress the deviation of the irradiation position of the reproduction beam due to the wavelength fluctuation of the laser light source. For this reason, the signal quality in hologram recording / reproduction can be improved.

  In addition, when wavelength multiplex recording / reproduction is performed using a wavelength tunable light source as a laser light source, it is possible to suppress a shift in recording position and / or reproduction position accompanying a change in wavelength, thereby stabilizing signal quality in hologram recording / reproduction. It can be made.

  The embodiment described above relates to a coaxial hologram recording / reproducing apparatus and a coaxial hologram recording / reproducing method, but the scope of application of the present invention is not limited to this. That is, even in the case of the two-beam method in which the signal light and the reference light are made into independent beams, and the hologram recording is performed by intersecting in the hologram medium, the same effect can be obtained by applying the same method. it can.

It is a figure typically shown focusing on the principal part of the hologram recording / reproducing apparatus of an embodiment. It is a figure explaining the diffraction conditions in the case of using DMD (DMD) as an example of a spatial light modulator. It is a drawing substitute photograph which shows the effect of this embodiment as an experiment example. It is a figure explaining the diffraction conditions in the case of using GLV (GLV) as a spatial light modulator. It is a figure which shows typically centering on the principal part of the hologram recording / reproducing apparatus of embodiment using another spatial light modulator.

Explanation of symbols

  10, 30 Hologram recording / reproducing apparatus, 11 Laser light source, 12 Collimate lens, 13, 14 Mirror, 15, 18 Angle adjustment mechanism, 16 Incident light beam, 17, 117 Spatial light modulator, 19 Signal light, 20 Reference light, 21 Objective lens, 22 hologram medium, 23 condenser lens, 24 array type photodetector, 27 control unit, d pixel pitch, δz hinge depth change, δθin incident angle change, δθout emission angle change, δλ wavelength change, δφ angle Correction amount, θin incident angle, θout emission angle, φ Reflection surface angle

Claims (6)

A light beam from a laser light source is guided to a spatial light modulator to irradiate the hologram medium with a modulated light beam subjected to spatial modulation, and record data is recorded as a hologram, or the hologram is recorded on the hologram recorded on the hologram medium. In a hologram recording or reproducing apparatus for reproducing the recording data by irradiating a modulated light beam,
Detecting the wavelength of the light beam from the laser light source;
The relative angle between the spatial light modulator and the light beam incident on the spatial light modulator is changed according to the wavelength of the light beam, and the modulated light beam emitted from the spatial light modulator is changed. A hologram recording or reproducing apparatus characterized in that an emission angle is set to a predetermined direction. An angle adjustment mechanism for rotating the spatial light modulator;
The hologram recording or reproducing apparatus according to claim 1, wherein the angle adjusting mechanism is controlled in accordance with a wavelength of a light beam from the laser light source. 2. The hologram recording or reproducing apparatus according to claim 1, wherein an angle of the light beam incident on the spatial light modulator is changed according to a wavelength of the light beam from the laser light source. A light beam from a laser light source is guided to a spatial light modulator to irradiate the hologram medium with a modulated light beam subjected to spatial modulation, and record data is recorded as a hologram, or the hologram is recorded on the hologram recorded on the hologram medium. In a hologram recording apparatus or hologram reproducing apparatus that reproduces the recording data by irradiating a modulated light beam,
Detecting the wavelength of the light beam from the laser light source;
The pixel reflection surface depth of the diffraction grating of the spatial light modulator is controlled according to the wavelength of the light beam, and the emission angle of the modulated light beam emitted from the spatial light modulator is set to a predetermined direction. A hologram recording or reproducing apparatus characterized by the above. A light beam from a laser light source is guided to a spatial light modulator to irradiate a modulated light beam subjected to spatial modulation onto a hologram medium, and record data is recorded as a hologram, or recorded on the hologram medium. In the method of recording or reproducing the hologram, reproducing the recording data by irradiating the modulated light beam,
Detecting the wavelength of the light beam from the laser light source;
Changing the relative angle between the spatial light modulator and the light beam incident on the spatial light modulator according to the wavelength of the light beam;
A hologram recording or reproducing method, wherein an outgoing angle of the modulated light beam emitted from the spatial light modulator is set to a predetermined direction. A light beam from a laser light source is guided to a spatial light modulator to irradiate the hologram medium with a modulated light beam subjected to spatial modulation, and record data is recorded as a hologram, or the hologram is recorded on the hologram recorded on the hologram medium. In a hologram recording or reproducing method for reproducing the recording data by irradiating a modulated light beam,
Detecting the wavelength of the light beam from the laser light source;
The pixel reflection surface depth of the diffraction grating of the spatial light modulator is controlled according to the wavelength of the light beam, and the emission angle of the modulated light beam emitted from the spatial light modulator is set to a predetermined direction. A hologram recording or reproducing method characterized by the above.

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