JP2000162950A - Hologram recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable controlling the propagation direction of light and to realize multiple recording as the combination of wavelength and angle multiple recording by using a light source which can change the wavelength of the emitting light and using a dispersion optical element where the light enters. SOLUTION: In a beam deflector 11, the oscillation wavelength of laser light is controlled by changing the frequency of ultrasonic waves applied from an ultrasonic generating mechanism 13 to an acousto-optical element 14. When the wavelength of the laser light entering the diffraction grating 16 is changed, the direction of the diffracted light by the diffraction grating 16 is changed. The laser light with controlled wavelength and propagation direction is divided into two beams by a beam splitter 22. One beam is the object light, which is reflected by a mirror 23 and enters a spacial modulator 24. The beam is spatially modulated by the spacial modulator 24 corresponding to the image to be recorded in the hologram and the beam enters the hologram recording medium 25. The other beam is the reference light, which is reflected by a mirror 26 and enters the hologram recording medium 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram recording apparatus for performing multiplex recording of a hologram.

[0002]

2. Description of the Related Art In a volume hologram in which a hologram is three-dimensionally recorded on a hologram recording medium, multiplex recording of a hologram is possible by changing the angle of one or both of a reference beam and an object beam. . Note that such multiplex recording is called angle multiplex recording.

In order to perform angle multiplex recording of a hologram, a deflecting means (a so-called beam deflector) for changing the propagation direction of light is required. Conventionally, as a beam deflector, mechanical means using a galvanometer mirror or the like, an acousto-optic deflector (AOD), an electro-optic deflector (EO)
D) and the like. FIG. 8 shows an example of a beam deflector using the acousto-optic deflector 101, and FIG. 9 shows an example of a beam deflector using the galvanomirror 102.

A beam deflector used for angle multiplex recording of a hologram preferably has a large number of resolution points when changing the propagation direction of light in order to increase the degree of multiplicity during angle multiplex recording. Assuming that the width N of the aperture of the deflector is D, the shape factor of the aperture is a, the wavelength of light is λ, and the angle amplitude when the propagation direction of light is changed is φ, the following equation ( It is represented by 1). The shape factor a of the aperture is a = 1.22 when the aperture is circular, and a = 1 when the aperture is rectangular.

N = φD / aλ (1) As can be seen from the above equation (1), the larger the aperture of the deflector, and the larger the angular amplitude when the light propagation direction is changed ( That is, the larger the beam deflection angle), the greater the number of decomposition points of the beam deflector. However, when the aperture of the deflector becomes large, the optical system becomes large and the practicality becomes low. Since the product of the incident height and the incident angle on each surface is constant from the relationship of Lagrange Helmholtz, even if the beam shaping optical systems 104 and 105 are arranged before and after the beam deflector 103 as shown in FIG. The deflector decomposition point is invariant.

[0006]

In angle multiplex recording of a hologram, recording and reproduction are performed by changing the angle of one or both of the reference light and the object light. It must be performed with a reproducibility with an accuracy of a few degrees. However, a mechanical beam deflector using a galvanometer mirror or the like has a problem in accuracy including reproducibility.

On the other hand, an electric beam deflector using an acousto-optic deflector or an electro-optic deflector has a problem that the number of resolution points is small and the multiplicity during angle multiplex recording cannot be increased. For example, with a beam deflector using an acousto-optic deflector, only about 1000 decomposition points can be obtained. Further, in the case of a beam deflector using an electro-optical deflector, the number of decomposition points can be obtained at most only about several tens.

As described above, conventionally, both increasing the number of decomposition points when changing the propagation direction of light and performing accurate and reproducible angle control when changing the propagation direction of light are compatible. I couldn't do that. Therefore, when controlling the propagation direction of light, the number of decomposition points increases,
In addition, it is desired that the angle control be performed with high accuracy and reproducibility.

By the way, a hologram is, for example, "Scott
As described in Campbell et al. Optics Letter, pp. 2161, 19, 1994, multiplex recording can be performed by changing the wavelength. In this case, multiplex recording of holograms can be performed without a beam deflector. Note that such multiplex recording is called wavelength multiplex recording.

If multiplex recording is performed by combining angle multiplex recording and wavelength multiplex recording, the degree of hologram multiplication can be further increased. However, conventionally, in order to perform multiplex recording by combining angle multiplex recording and wavelength multiplex recording,
It was necessary to combine a large number of semiconductor lasers and optical elements, and the hologram recording device became complicated, and its control was very difficult.

The present invention has been proposed in view of the above-described conventional circumstances, and it is possible to control the direction of light propagation with a high number of resolution points and with high accuracy.
It is an object of the present invention to provide a hologram recording apparatus that can realize multiplex recording combining wavelength multiplex recording and angle multiplex recording with a simple configuration.

[0012]

A hologram recording apparatus according to the present invention includes a light source capable of changing the wavelength of emitted light, and a dispersive optical element on which the light emitted from the light source is incident. By controlling the wavelength of the light emitted from the light source and changing the propagation direction of the light by a dispersive optical element according to the wavelength, the wavelength and the propagation direction of the light are simultaneously controlled. Perform wavelength and angle multiplex recording. In this hologram recording device, since the light propagation direction is controlled by controlling the light wavelength, the control of the light wavelength and the control of the light propagation direction can be easily performed simultaneously.

Further, in the hologram recording apparatus according to the present invention, after the diameter of the light emitted from the light source is enlarged by the light enlarging means, the light emitted from the light source is incident on the dispersion optical element. By expanding the diameter of the light when the light is incident on the dispersive optical element, the number of decomposition points when changing the propagation direction of the light by the dispersive optical element can be increased.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an outline of an example of a beam deflector which is a main part of a hologram recording apparatus to which the present invention is applied. First, in this beam deflector 1,
Only a specific wavelength is fed back to the wavelength tunable laser 2 by a wavelength selection filter 3 installed outside the wavelength tunable laser 2 to constitute an external cavity laser 4. Due to this feedback, the oscillation wavelength of the laser light is narrowed. Next, light emitted from the external cavity laser 4 is made incident on the dispersion optical element 5. At this time, if the oscillation wavelength of the laser light is changed by the wavelength selection filter 3, the propagation direction of the light emitted through the dispersion optical element 5 changes.

The number of decomposition points N when changing the light propagation direction by the beam deflector 1 is determined by the tuning width of the oscillation wavelength of the laser light and the beam diameter of the laser light incident on the dispersion optical element 5.

For example, it is assumed that a diffraction grating 5a having a period Λ as shown in FIG. 2 is used as the dispersion optical element 5. The center wavelength of the laser light is λ, the oscillation wavelength is λ−Δλ to λ + Δλ, the aperture of the diffraction grating 5a (that is, the beam diameter of the laser light incident on the diffraction grating 5a) is D, and the shape factor of the aperture is a (circular). At 1.2
2, rectangular and 1). At this time, the diffraction angle θ of the diffraction grating 5a is given by θ = λ / Λ. Therefore, the change Δθ of the diffraction angle with respect to the wavelength change Δλ is Δθ = Δλ / Λ
It is represented by

Then, as shown in FIG. 2, the diffraction grating 5a
When the light diffracted by the laser beam (that is, the light emitted from the beam deflector) is condensed by the lens 6 having the focal length f, the number of decomposition points N of the light on the focal plane is large if Δλ is sufficiently smaller than λ. It is expressed by the ratio between the maximum movement distance of the spot and the spot diameter at the center wavelength. Therefore, when a diffraction grating 5a having a period Λ as shown in FIG. 2 is used, the number of decomposition points N of the beam deflector 1 is represented by the following equation (2).

N ≒ 2 · f · Δθ / (a · λ / NA) = 2 · f · Δθ / {a · λ · f / (D / 2)} = D · Δθ / (a · λ) = D [Delta] [lambda] / (a [lambda] [lambda]) (2) Therefore, if the beam diameter D of the laser beam incident on the diffraction grating 5a is increased, the number of decomposition points N can be easily increased. In the configuration as shown in FIG. 1, it is easy to increase the beam diameter D. For example,
a = 1, λ = 0.65 μm, Δλ = 0.02 μm, Λ =
If 0.4 μm and D = 130 mm, the number of decomposition points N = 1
0000. This is an order of magnitude larger than the resolution of a beam deflector using a general acousto-optic deflector.

In an acousto-optic deflector, tellurium dioxide (Te)
An optical crystal such as O ₂ ) or lithium niobate (LiNbO ₃ ) is used as a medium for transmitting ultrasonic waves. However, in order to increase the beam diameter D, it is necessary to use a large and high-quality optical crystal in order to cope with it. Become. However, the use of large, high quality optical crystals significantly increases costs. Further, when a large-sized optical crystal is used, the propagation distance of the ultrasonic wave becomes long, and thus material difficulties such as absorption of the sound wave occur. For this reason, it is difficult for the acousto-optic deflector to increase the beam diameter D and increase the number of decomposition points N.

On the other hand, a large diffraction grating can be easily manufactured. Therefore, it is easy to increase the beam diameter D and increase the number N of decomposition points. In addition, since a replica of the diffraction grating can be manufactured, cost can be significantly reduced by mass production.

The size can be increased by mechanical means using a galvanometer mirror or the like. However, in this case, there are problems in that accuracy is mechanically limited and reproducibility is low. In general, it is difficult to increase the modulation band by mechanical scanning. Furthermore, since the mechanical stage also causes vibration, it becomes a serious problem for applications that are easily affected by vibration such as hologram recording. On the other hand, the configuration as shown in FIG. 1 has an advantage in that both a high number of decomposition points and a non-mechanical operation can be achieved.

Next, FIG. 3 shows a specific configuration example of a beam deflector which is a main part of a hologram recording apparatus to which the present invention is applied.

In this beam deflector 11, first,
Laser light L1 from a laser light source capable of changing the wavelength of emitted light is made incident on an acousto-optic element 14 to which an ultrasonic wave generating mechanism 13 is attached via a beam splitter 12. At this time, the ultrasonic wave generating mechanism 13
Is applied to the acousto-optic element 14, the photoelastic effect of the ultrasound causes a change in the refractive index of the acousto-optic element 14, and a diffraction grating is formed inside the acousto-optic element 14. Then, of the incident light incident on the acousto-optic element 14 by the diffraction grating formed on the acousto-optic element 14,
Light in a specific narrow wavelength range that satisfies the Bragg condition is Bragg reflected.

A part of the reflected light L2 from the acousto-optic element 14 passes through the beam splitter 12 and returns to the laser light source. The laser light source is injection-locked by the return light, and the oscillation wavelength of the laser light is narrowed to the wavelength range of the return light. At this time, if the frequency of the ultrasonic wave applied from the ultrasonic wave generating mechanism 13 to the acousto-optic element 14 is changed, the wavelength of the light reflected by the acousto-optic element 14 changes, so that the oscillation wavelength of the laser light changes. Therefore, in the beam deflector 11, the oscillation wavelength of the laser light is controlled by changing the frequency of the ultrasonic wave applied from the ultrasonic wave generating mechanism 13 to the acousto-optic element 14.

The reflected light L2 from the acousto-optic element 14
Of the light, the light reflected by the beam splitter 12 has its beam diameter expanded by the beam expander 15,
The light enters the diffraction grating 16 and is reflected by the diffraction grating 16. At this time, if the wavelength of the laser light incident on the diffraction grating 16 changes, the direction of the light diffracted by the diffraction grating 16 changes.

Therefore, by controlling the oscillation wavelength of the laser light as described above, it is possible to simultaneously control the wavelength of the emitted light diffracted by the diffraction grating 16 and the propagation direction thereof. That is, the beam deflector 11 has both the function of controlling the oscillation wavelength of the laser light and the function of a beam deflector for controlling the propagation direction of the laser light.

FIG. 4 shows a configuration example of a hologram recording apparatus using the beam deflector 11. Note that FIG. 4 shows only the optical system components having a minimum required amount, but it goes without saying that optical components such as lenses and wave plates may be arranged in the optical path as needed.

In the hologram recording device 21 shown in FIG.
First, a laser beam whose wavelength and propagation direction are controlled by the beam deflector 11 is transmitted to the beam splitter 2.
The light is divided into two light beams by 2. One light is an object light, is reflected by the mirror 23 and enters the spatial modulator 24. Then, the light is spatially modulated by the spatial modulator 24 so as to correspond to the image to be recorded on the hologram, and then enters the hologram recording medium 25. The other light is light serving as reference light, is reflected by the mirror 26 and enters the hologram recording medium 25. Thus, the hologram recording medium 2
The object light and the reference light incident on 5 interfere inside the hologram recording medium 25, and interference fringes generated thereby are recorded as holograms on the hologram recording medium 25.

In the hologram recording apparatus 21, holograms are multiplex-recorded by the beam deflector 11 while changing the oscillation wavelength and the propagation direction of the laser light. Thereby, multiplex recording combining angle multiplex recording and wavelength multiplex recording is achieved, and the hologram multiplicity can be greatly increased.

When reproducing the hologram recorded as described above, only the reference light having the same wavelength and the same propagation direction as the recording is incident on the hologram recording medium 25. Then, the reproduced hologram is transferred to, for example, a CCD (charge
-coupled device).

In the beam deflector 11 shown in FIG. 3, the reflection type acousto-optic device 14 and the diffraction grating 16
Are combined to control the oscillation wavelength and the propagation direction of the laser light, but other functions can also realize the same function.

For example, as shown in FIG.
With the use of the laser beam, the oscillation wavelength and the propagation direction of the laser beam can be controlled.

In the beam deflector 31A shown in FIG. 5, a semiconductor laser 32 is used as a light source capable of changing the wavelength of emitted light. Then, the laser light emitted from the semiconductor laser 32 is first converted into parallel light by the collimator lens 33 and then enters the beam splitter 34. The light transmitted through the beam splitter 34 enters the first diffraction grating 35, while the light reflected by the beam splitter 34 enters the second diffraction grating 36.

Then, of the light incident on the first diffraction grating 35, light in a specific narrow wavelength range is Bragg-reflected, and this reflected light returns to the semiconductor laser 32 via the beam splitter 34. That is, the first diffraction grating 35 reflects only the wavelength satisfying the Bragg condition toward the semiconductor laser 32. Then, the semiconductor laser 32 is injection-locked by the light returned to the semiconductor laser 32 in this manner, and the oscillation wavelength of the laser light is narrowed to the wavelength range of the returned light.

At this time, if the angle of the first diffraction grating 35 is changed, the wavelength that satisfies the Bragg condition changes, so that the semiconductor laser 3 is reflected by the first diffraction grating 35 and
The wavelength of the light returning to 2 changes, and as a result, the oscillation wavelength of the laser light changes. Therefore, in the beam deflector 31A, the oscillation wavelength of the laser light is controlled by changing the angle of the first diffraction grating 35.

Further, of the laser light from the semiconductor laser 32, the light reflected by the beam splitter 34 is:
The light is incident on the second diffraction grating 36 and the second diffraction grating 36
Is reflected by Bragg. At this time, if the wavelength of the laser light incident on the second diffraction grating 36 changes, the direction of the light diffracted by the second diffraction grating 36 changes.

Therefore, by controlling the oscillation wavelength of the laser beam using the first diffraction grating 35 as described above,
The wavelength of the emitted light that is diffracted and emitted by the second diffraction grating 36 and the propagation direction thereof can be simultaneously controlled. That is, in the beam deflector 31A, the oscillation wavelength of the laser beam and the propagation direction of the laser beam can be simultaneously controlled just by changing the angle of the first diffraction grating 35, similarly to the above-described beam deflector 11. it can.

In the beam deflector 31A, it is necessary to mechanically control the angle of the first diffraction grating 35. However, the angular amplitude required for the first diffraction grating 35 is much smaller than when a beam deflector is configured using a galvanomirror or the like. Therefore, for controlling the angle of the first diffraction grating 35, it is possible to use an element that operates with high precision and low vibration such as a piezo element. In this case, the mechanical mechanism is almost a problem. Does not.

As shown in FIG. 6, even if the first diffraction grating 35 in the beam deflector 31A shown in FIG. 5 is replaced by a phase conjugate mirror 37, the oscillation wavelength and the propagation direction of the laser light can be controlled simultaneously. Can be.

In the beam deflector 31B shown in FIG. 6, the angle of the phase conjugate mirror 37 is changed by using a rotation mechanism using a piezo element or the like, and the angle of incidence of the laser beam on the phase conjugate mirror 37 is changed. Controls the oscillation wavelength of light. Also in this beam deflector 31B, just by changing the angle of the phase conjugate mirror 37, similarly to the above-described beam deflectors 11 and 31A, the oscillation wavelength of the laser light and
The direction of propagation of the laser light can be controlled simultaneously.

Since the phase conjugate mirror 37 reflects light having exactly the same wavefront as the incident wavefront, the use of the phase conjugate mirror 37 has the advantage that the injection lock can be accurately applied. In particular, if a self-induced arrangement is adopted, phase conjugate light can be generated with high efficiency with a simple configuration (M. Lobel et al. Pp.2000, Vol.15, Journal of
Optical Society of America B, 1998).

Further, as shown in FIG. 7, the oscillation wavelength and the propagation direction of the laser beam can be controlled by combining a transmission type acousto-optic element and a diffraction grating.

In the beam deflector 41 shown in FIG.
The semiconductor laser 42 is used as a light source that can change the wavelength of emitted light. Then, the laser light emitted from the semiconductor laser 42 is first converted into parallel light by the collimator lens 43 and then enters the beam splitter 44. The light transmitted through the beam splitter 44 is incident on a transmission type acousto-optic element 45 to which an ultrasonic wave generating mechanism is attached, while the light reflected by the beam splitter 44 is incident on a diffraction grating 46.

At this time, when the ultrasonic wave from the ultrasonic wave generating mechanism is applied to the acousto-optic element 45, a refractive index change occurs in the acousto-optic element 45 due to the photoelastic effect of the ultrasound and the diffraction occurs inside the acousto-optic element 45 A grid is formed. Then, of the light incident on the acousto-optic element 45, only light in a specific narrow wavelength range satisfying the Bragg condition is diffracted by the diffraction grating formed on the acousto-optic element 45.

Here, a lens 47 and a pinhole 48 are arranged downstream of the acousto-optic element 45. Then, only a part of the wavelength component diffracted by the acousto-optical element 45 is condensed by the lens 47 and passes through the pinhole 48, and the other wavelength components are shielded on the focal plane condensed by the lens 47. Keep it.

The light passing through the pinhole 48 is reflected by a concave mirror 49 provided at a position where the pinhole 48 is the focal plane, returns to the original optical path, and returns to the semiconductor laser 42. Then, the semiconductor laser 42 is injection-locked by the light returned to the semiconductor laser 42 in this manner, and the oscillation wavelength of the laser light is narrowed to the wavelength range of the returned light.

Here, if the frequency of the ultrasonic wave applied to the acousto-optic element 45 is changed, the wavelength of the light passing through the pinhole 48 changes, so that the wavelength of the return light returning to the semiconductor laser 42 changes. As a result, the oscillation wavelength of the laser light can be controlled. Therefore, in the beam deflector 41, the acousto-optic device 45
The oscillation wavelength of the laser light is controlled by changing the frequency of the ultrasonic wave applied to the laser beam.

Also, of the laser light from the semiconductor laser 42, the light reflected by the beam splitter 44 is:
The light enters the diffraction grating 46 and is Bragg-reflected by the diffraction grating 46. At this time, if the wavelength of the laser light incident on the diffraction grating 46 changes, the direction of the light diffracted by the diffraction grating 46 changes.

Therefore, as described above, the acousto-optic device 4
By controlling the oscillation wavelength of the laser light by using 5, the wavelength of the outgoing light diffracted by the diffraction grating 46 and the propagation direction thereof can be simultaneously controlled. That is, in the beam deflector 41, only by changing the frequency of the ultrasonic wave applied to the transmission type acousto-optic element 45,
Similarly to the above-described beam deflectors 11, 31A and 31B, the oscillation wavelength of the laser light and the propagation direction of the laser light can be simultaneously controlled.

In the beam deflectors 11, 31A, 31B, and 41 described in the above examples, injection locking is performed by using an external resonator, and a beam splitter is disposed inside the external resonator. To extract light. However, in the present invention, the injection locking method and the method of extracting light from the external resonator are not particularly limited, and any method can be applied. Therefore, for example, one end of the external resonator may be a half mirror to extract light from the external resonator itself, or light emitted from the other end of the laser light source may be extracted.

In the beam deflectors 11, 31A, 31B, and 41 described above, the wavelength of light is controlled by applying an injection lock using an external resonator. As a laser light source used at this time, a semiconductor laser having a wide gain width is preferable. When a semiconductor laser is used, the device can be miniaturized and the photoelectric conversion efficiency can be increased, which is very preferable in practical use.

However, usable laser light sources are not limited to semiconductor lasers, and various laser light sources can be used. For example, as other tunable lasers, for example, Ti: Saphire, Cr: LiSA
There are also a tunable solid-state laser using F, Ce: LiSAF or Alexandrite, a fiber laser doped with erbium, eurobium, or the like, and various dye lasers. These can also be used as the light source in the present invention.

In the beam deflectors 11, 31A, 31B, and 41 described in the above examples, the wavelength of light is controlled by applying an injection lock using an external resonator. The light source used may be any as long as it can change the wavelength of the emitted light regardless of the presence or absence of the injection lock.
Therefore, for example, optical parametric oscillation, DFB,
A light source that can directly control the wavelength of the laser light without using an external resonator, such as a wavelength-variable semiconductor laser with a narrow band such as a DBR, may be used. If necessary, a plurality of means described in the above description may be used in combination.

When the wavelength can be directly controlled without using an external resonator, the light emitted from the light source may be directly incident on the dispersion optical element. In this case, by directly controlling the wavelength of the light emitted from the light source, the wavelength of the light incident on the dispersion optical element changes, and as a result, the direction of the light beam can be controlled.

In the beam deflectors 11, 31A, 31B, and 41 described in the above examples, a diffraction grating is used as a dispersive optical element. It is only necessary to be able to change in response to the change. For example, a prism, a hologram element, a photonic crystal, or the like can be used. However, diffraction gratings can easily increase the resolution with respect to wavelength,
Practically, a diffraction grating is most preferable.

The hologram recording device 2 shown in FIG.
In No. 1, the multiplexed recording of the hologram is performed by combining the wavelength multiplexing recording and the angle multiplexing recording.
There are various methods such as shift multiplex recording, phase code multiplex recording, peristrographic multiplex recording, and fractal multiplex recording. The present invention can be combined with these multiple recordings.

By the way, in order to prevent a hologram recorded on a hologram recording medium made of a photorefractive crystal or the like from being destroyed by exposure during reproduction, a method of recording a hologram using two wavelengths has been devised. , Its effects have been demonstrated (USP5665493 Bai
et al, YSBai and R. Kachru, Phys. Rev. Lett, 78, 29
44, 1997, D. Lande et al, 22, 1722, 1997, JP-A-10-
No. 45497, JP-A-10-45498). In these, crystals such as Pr: LiNbO ₃ and Pr: LiTaO ₃ are used as a hologram recording medium. Then, when recording a hologram, the lower level electrons are excited to an intermediate level by blue light of about 450 nm, and thereafter, 850 nm
A two-stage process of recording a hologram with a degree of infrared light is used. In the wavelength region around 850 nm, a wavelength tunable semiconductor laser having a high output and a wide gain width has been developed. Therefore, the present invention can be easily combined with such a method.

The hologram recording apparatus according to the present invention is an apparatus for recording an image as a hologram, but the hologram recording apparatus according to the present invention converts arbitrary information into an image and records the image as a hologram. By doing so, it goes without saying that the device can be used as a general-purpose information recording device regardless of the type of information to be recorded.

[0060]

As described in detail above, in the hologram recording apparatus according to the present invention, wavelength multiplex recording and angle multiplex recording can be simultaneously performed with a simple configuration. Therefore, in the hologram recording device according to the present invention, the hologram multiplicity can be increased with a simple configuration. Moreover, in the hologram recording apparatus according to the present invention, the propagation direction can be controlled simultaneously only by controlling the wavelength of the light emitted from the light source. Is very simple.

In the hologram recording apparatus according to the present invention, the direction of light propagation is changed by the dispersion optical element, so that the hologram recording apparatus is more stable than a mechanical beam deflector using a galvanometer mirror or the like. Performance and accuracy are improved. Further, compared with the case where a beam deflector using an acousto-optic element is used, it is not necessary to increase the aspect ratio of the aperture, so that the optical system is relatively simple and the size can be easily reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of an example of a beam deflector used in a hologram recording device to which the present invention is applied.

FIG. 2 is a diagram illustrating the number of decomposition points N when a diffraction grating is used as a dispersion optical element.

FIG. 3 is a diagram illustrating a configuration example of a beam deflector used in a hologram recording device to which the present invention has been applied.

FIG. 4 is a diagram showing a configuration example of a hologram recording device to which the present invention is applied.

FIG. 5 is a diagram showing another configuration example of the beam deflector used in the hologram recording device to which the present invention is applied.

FIG. 6 is a diagram showing another configuration example of the beam deflector used in the hologram recording device to which the present invention is applied.

FIG. 7 is a diagram illustrating another configuration example of the beam deflector used in the hologram recording device to which the present invention is applied.

FIG. 8 is a diagram showing a configuration example of a beam deflector used in a conventional hologram recording device.

FIG. 9 is a diagram showing another configuration example of the beam deflector used in the conventional hologram recording device.

FIG. 10 is a diagram showing an optical system in which a beam shaping optical system is arranged before and after a beam deflector.

[Explanation of symbols]

1 beam deflector, 2 wavelength tunable laser,
3 wavelength selection filter, 4 external cavity laser,
5 dispersive optics, 11 beam deflector,
12 beam splitter, 13 ultrasonic generating mechanism,
14 acousto-optic element, 15 beam expander, 16 diffraction grating, 22 beam splitter,
23 mirror, 24 spatial modulator, 25 hologram recording medium, 26 mirror

Claims (4)

[Claims] 1. A light source capable of changing the wavelength of emitted light, and a dispersive optical element on which light emitted from the light source is incident, wherein the wavelength of the light emitted from the light source is controlled. ,
By changing the propagation direction by the dispersive optical element according to the wavelength, the wavelength and the propagation direction of light are simultaneously controlled,
A hologram recording apparatus for performing wavelength and angle multiplex recording of a hologram using the light. 2. The hologram recording apparatus according to claim 1, wherein the light source changes the wavelength of the emitted light by using an external resonator provided with a wavelength selecting means. 3. The hologram recording apparatus according to claim 1, wherein the light source is a semiconductor laser, a solid-state laser, a fiber laser, or a dye laser capable of changing a wavelength of emitted light. 4. The hologram recording apparatus according to claim 1, wherein the dispersion optical element is a diffraction grating, a prism, a hologram element, or a photonic crystal.