JP2005003828A - Hologram recording apparatus and hologram recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hologram recording apparatus and a hologram recording method in which laser beam is rapidly controlled and data are recorded on a hologram recording medium. <P>SOLUTION: The laser beam before division into signal light and reference light or laser light which is reference light passes through a diffracted state switching element and a light shielding element. The diffracted state switching element is capable of switching the diffracted state of laser light in one of first and second diffracted states, and the light shielding element passes through laser beam in the first diffracted state and shields the laser beam in the second diffracted state. Therefore, by switching the diffracted state of the laser beam with the diffracted state switching element, passing/shielding of laser light can be rapidly switched. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hologram recording apparatus and a hologram recording method for recording data on a hologram recording medium.
[0002]
[Prior art]
Hologram recording apparatuses that record data on a hologram recording medium using holography have been developed. Holography divides laser light into signal light and reference light, and uses these interferences. Therefore, the laser light needs high wavelength stability. For this reason, in the hologram recording apparatus, a laser beam is generated by using a light source having a stable oscillation wavelength and generating a second harmonic by causing the laser beam from the light source to enter the second harmonic generation material as necessary. Are often used with shorter wavelengths. This is because if the wavelength from the light source is stable, the wavelength of the second harmonic is also stable. For example, LiNbO specially processed for 1064 nm light emitted from a YAG laser ₃ 532 nm laser light can be generated.
[0003]
A technique related to modulation of reference light is disclosed (see Patent Document 1).
[0004]
[Patent Document 1]
JP 2001-256654 A
[Problems to be solved by the invention]
However, when shortening the wavelength using the second harmonic, even if the laser light from the light source is turned on, the second harmonic is not generated immediately, and the laser light from the light source is turned off. However, the second harmonic does not turn off immediately. That is, complete control of ON / OFF of laser light becomes difficult with a single laser light source.
[0005]
On the other hand, when recording data on a hologram recording medium, in many cases, recording is performed by irradiating laser light, and then multiplex recording is performed by shifting the incident angle or the incident position of the laser light.
[0006]
In order to perform recording on the hologram recording medium satisfactorily, it is desirable not to irradiate the hologram recording medium with laser light while the angle is shifted or the position is shifted. In other words, it is necessary to accurately control the ON / OFF of the laser beam, which does not match the above-described harmonic ON / OFF characteristics.
[0007]
In view of the above, it is an object of the present invention to provide a hologram recording apparatus and a hologram recording method for recording data onto a hologram recording medium by quickly controlling laser light.
[0008]
[Means for Solving the Problems]
A. In view of the above, a hologram recording apparatus according to the present invention diffracts a laser light source that emits laser light, and the laser light emitted from the laser light source, and switches the diffraction state between the first and second diffraction states. A possible diffractive state switching element, a light shielding element that allows laser light diffracted by the diffractive state switching element to pass in the first diffractive state and shields in the second diffractive state, and the light shielding A light splitting element that splits laser light emitted from the element into signal light and reference light; a light modulating element that modulates signal light emitted from the light splitting element; and signal light emitted from the light modulating element A first condensing element for condensing the light onto the hologram recording medium, and the reference light emitted from the light splitting element is condensed at substantially the same location as the signal light collected by the first condensing element. A second light collecting element; Characterized in that it.
[0009]
Laser light emitted from the laser light source passes through the diffraction state switching element and the light shielding element. The diffraction state switching element can switch the diffraction state of the laser light between the first and second diffraction states, and the light shielding element passes through the laser light in the first diffraction state, and the laser light in the second diffraction state. Shield. For this reason, by switching the diffraction state of the laser light by the diffraction state switching element, it is possible to quickly switch the passage / shielding of the laser light.
(1) The diffraction state switching element may include first and second phase control elements that control the phase difference of the emitted light from each.
[0010]
By controlling the phase difference between the outgoing lights emitted from the first and second phase control elements, the diffraction state of the light synthesized from the outgoing lights can be controlled. In this case, a third or more phase control element may be added.
[0011]
Here, since the first and second phase control elements are often small to a certain degree (about the wavelength of light or smaller), the light emitted from each of these is controlled by the first and second phase control elements. Usually, it is diffracted diffracted light.
[0012]
Each of the first and second phase control elements can take various shapes, but as an example, it can have a substantially ribbon shape.
[0013]
This shape is easy to create and drive. For example, when the ribbon is made of a conductive and elastic material (for example, a metal material), the ribbon is displaced by an electrostatic force based on the voltage applied to the ribbon, and the original state (shape) due to the elasticity of the ribbon. Can be restored. In this way, the first and second phase control elements, and hence the diffraction state switching element, can be operated at a high speed (for example, about 1 μsec).
(2) As the light modulation element, a diffraction control element or a liquid crystal element that emits light by controlling the diffraction state of incident light may be used, and control of signal light can be performed using various light modulation elements.
[0014]
B. The hologram recording apparatus according to the present invention includes a laser light source that emits laser light, a light splitting element that splits the laser light emitted from the laser light source into signal light and reference light, and light emitted from the light splitting element. A light modulation element that modulates the signal light, a first light collecting element that focuses the signal light emitted from the light modulation element on a hologram recording medium, and diffracts the reference light emitted from the light splitting element; In addition, the diffraction state switching element that can switch the diffraction state between the first and second diffraction states, and the reference light diffracted by the diffraction state switching element are allowed to pass in the first diffraction state, and the first A light shielding element that shields in the second diffraction state, and a second light that condenses the reference light emitted from the light shielding element at substantially the same location as the signal light collected by the first light collecting element. And a condensing element. To.
[0015]
The reference light emitted from the light splitting element passes through the diffraction state switching element and the light shielding element. The diffraction state of the reference light can be switched between the first and second diffraction states by the diffraction state switching element, the light shielding element passes the reference light in the first diffraction state, and the reference light in the second diffraction state. Therefore, the passage / shielding of the reference light can be quickly switched by switching the diffraction state of the reference light by the diffraction state switching element.
(1) The diffraction state switching element may include first and second phase control elements that control the phase difference of the emitted light from each.
[0016]
By controlling the phase difference between the outgoing lights emitted from the first and second phase control elements, the diffraction state of the light synthesized from the outgoing lights can be controlled. In this case, a third or more phase control element may be added.
[0017]
Here, since the first and second phase control elements are often small to a certain degree (about the wavelength of light or smaller), the light emitted from each of these is controlled by the first and second phase control elements. Usually, it is diffracted diffracted light.
[0018]
Each of the first and second phase control elements can take various shapes, but as an example, it can have a substantially ribbon shape.
[0019]
This shape is easy to create and drive. For example, when the ribbon is made of a conductive and elastic material (for example, a metal material), the ribbon is displaced by an electrostatic force based on the voltage applied to the ribbon, and the original state (shape) due to the elasticity of the ribbon. Can be restored. In this way, the first and second phase control elements, and hence the diffraction state switching element, can be operated at a high speed (for example, about 1 μsec).
(2) The light modulation element may be a diffraction control element that emits light by controlling the diffraction state of incident light, or a liquid crystal element. Signal light can be controlled using various light modulation elements.
[0020]
C. In the hologram recording method according to the present invention, a diffraction step of diffracting in any one of the first and second diffraction states capable of switching the laser light emitted from the laser light source, and the laser light diffracted in the diffraction step, A light shielding step for passing in the first diffraction state and a light shielding step for shielding in the second diffraction state, and an output emitted by the light shielding step when the laser light is allowed to pass in the light shielding step. A light splitting step for splitting the emitted light into a signal light and a reference light; a light modulating step for modulating the signal light emitted in the light splitting step when the laser light is passed in the light shielding step; and the light A first condensing step for condensing the signal light modulated in the light modulation step onto a hologram recording medium when the laser light is passed in the shielding step; A second condensing step for condensing the reference light divided in the light dividing step at substantially the same location as the signal light condensed in the first condensing step when the light is allowed to pass through; It is characterized by comprising.
[0021]
The laser light emitted from the laser light source is diffracted in either of the switchable first and second diffraction states, and then passes through in the first diffraction state, and is shielded in the second diffraction state. The For this reason, by switching the diffraction state of the laser beam, the passage / shielding of the laser beam can be switched quickly.
[0022]
D. The hologram recording method according to the present invention includes a light splitting step for splitting laser light emitted from a laser light source into signal light and reference light, a light modulation step for modulating the signal light split in the light splitting step, Either the first light condensing step for condensing the signal light modulated in the light modulation step on the hologram recording medium, or the first or second diffraction state in which the reference light divided in the light dividing step can be switched. A diffraction step for diffracting the light, a light shielding step for allowing the reference light diffracted in the diffraction step to pass in the first diffraction state, and shielding the light in the second diffraction state, and the light shielding step. A second condensing step for condensing the reference light at substantially the same location as the signal light collected in the first condensing step when the reference light is allowed to pass through Features .
[0023]
The reference light split from the laser light source is diffracted in one of the switchable first and second diffraction states, and then passed through in the first diffraction state and shielded in the second diffraction state. The For this reason, by switching the diffraction state of the reference light, it is possible to quickly switch the passage / shielding of the laser light.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a schematic diagram showing a hologram recording apparatus 100 according to the first embodiment of the present invention.
[0025]
As shown in FIG. 1, a hologram recording apparatus 100 includes a laser light source 10, a one-dimensional beam expander 20, a half mirror 30, a mirror 31, one-dimensional diffraction control elements 40 and 40a, slit elements 50 and 50a, and a cylindrical lens. 71 and 72, and convex lenses 81 to 85, which record and reproduce information on the hologram recording medium M.
(Internal configuration of the one-dimensional diffraction control elements 40 and 40a)
First, the one-dimensional diffraction control element 40 will be described.
[0026]
FIG. 2 is a top view illustrating a state in which the one-dimensional diffraction control element 40 is viewed from above.
FIGS. 3 and 4 are a side view and a front view, respectively, showing the one-dimensional diffraction control element 40 as viewed from the side and the front. 3A and 3B show two states (OFF, ON) of the individual diffraction control element 41, respectively. FIG. 4 schematically shows the operation state of the ribbon 42.
[0027]
The one-dimensional diffraction control element 40 includes a plurality of individual diffraction control elements 41 arranged in the Y direction. The individual diffraction control element 41 diffracts incident light and emits it as diffracted light, and can control the diffraction state independently of each other.
[0028]
The individual diffraction control element 41 includes six ribbons 42, an insulating film 43 facing the ribbon 42, and a counter electrode 44, and is configured on the substrate 45. Six ribbons 42 are driven up and down every other ribbon. By applying a voltage between the ribbon 42 and the counter electrode 44, an electrostatic force is generated during this time, and the ribbon 42 is attracted to the counter electrode 44 (ON state: FIGS. 4B and 5B). reference). When the voltage applied between the ribbon 42 and the counter electrode 44 is removed, the ribbon 42 returns to the original state by the elastic force of the ribbon 42 (OFF state: see FIGS. 3A and 4A). ).
[0029]
For example, the ribbon 42 may have a width of several μm, a length of about 100 μm, and a distance d of several hundred nm. At this time, the operation time of the ribbon 42 can be about 1 μs.
[0030]
Consider a case in which laser light is perpendicularly incident on the one-dimensional diffraction control element 40 (individual diffraction control element 41). As shown in FIG. 4A, if the six ribbons 42 of the individual diffraction control element 41 are on the same plane (OFF state), the laser light is reflected vertically as it is, and only the 0th-order diffracted light is generated. On the other hand, as shown in FIG. 4B, when every other ribbon 42 is lowered (ON state), the first-order diffracted light is also generated in addition to the zero-order diffracted light reflected vertically. The intensity of the second or higher order diffracted light is small and therefore neglected.
[0031]
At this time, the ratio of the 0th-order diffracted light and the 1st-order diffracted light from the one-dimensional diffraction control element 40 is determined by the distance d between the lowered ribbon 42 and the unfallen ribbon 42, and the distance d is λ / 4 (λ: laser light). ), Only the first-order diffracted light is emitted. That is, the 0th-order diffracted light from the lowered ribbon 42 and the 0th-order diffracted light from the ribbon 42 that has not fallen cancel each other out, and the intensity becomes 0, leaving only the 1st-order diffracted light (2 as described above). Ignore ingredients above and below).
[0032]
The diffracted light in the ON state of the individual diffraction control element 41 is light in which diffracted lights having a half-wave phase shift from each other from the lowered ribbon 42 and the unfallen ribbon 42 are mixed. That is, each ribbon 42 can be considered as a phase variable element that can vary the phase of the diffracted light diffracted from each of the ribbons 42 by the displacement.
[0033]
As described above, each of the individual diffraction control elements 41 constituting the one-dimensional diffraction control element 40 independently takes two diffraction states (OFF: only the 0th-order diffracted light, ON: only the first-order diffracted light), so that the number of pixels Data of the number of bits corresponding to (the number of individual diffraction control elements 41) can be expressed. For example, 1088 bits of data can be expressed by arranging 1088 individual diffraction control elements 41.
[0034]
The operation of the one-dimensional diffraction control element 40 (individual diffraction control element 41) when the laser beam is directly incident has been described above. The principle of operation is that the laser beam is incident on the one-dimensional diffraction control element 40 obliquely. The case is basically the same. However, since the optical path length difference is shorter in oblique incidence than in direct incidence, only the first-order diffracted light is emitted when the interval d is approximately (λ / 4) / cos θ (θ is a one-dimensional diffraction control element). 40).
[0035]
The one-dimensional diffraction control element 40 a can also have the same configuration as the one-dimensional diffraction control element 40. However, while the one-dimensional diffraction control element 40 is intended to express multi-bit data, the one-dimensional diffraction control element 40a only needs to be able to switch between two diffraction states of the reference light.
[0036]
For this reason, in the one-dimensional diffraction control element 40a, it is not necessary to individually turn on / off each individual diffraction control element 41. That is, it is only necessary to switch between the two diffraction states as a whole without providing a configuration for controlling the diffraction states independently of each other like the individual diffraction control element 41.
(Other components)
Hereinafter, components other than the one-dimensional diffraction control elements 40 and 40a will be described.
[0037]
The laser light source 10 is a light source that emits laser light.
[0038]
The one-dimensional beam expander 20 is configured by combining a plano-concave lens 21 having a semi-elliptical prism-shaped depression and an elliptic cylindrical lens 22 and expanding the beam diameter of incident light in a one-dimensional direction (Y direction). It is an optical element. By passing through the one-dimensional beam expander 20, the beam shape of the laser light emitted from the laser light source 10 is converted from a substantially circular shape to a substantially elliptic shape corresponding to the one-dimensional diffraction control elements 40 and 40a.
[0039]
The half mirror 30 is an optical element that branches incident light into two lights.
[0040]
The mirror 31 is a reflective element for converting the direction of the reference light.
[0041]
Each of the cylindrical lenses 71 and 72 is an optical element for collecting an incident light beam in the X direction. This condensing is performed in order to make the laser beam correspond to the size of the one-dimensional type diffraction control elements 40, 40a in the X direction.
[0042]
The convex lenses 81 and 84 are optical elements for forming a diffraction spectrum of diffracted light emitted from the one-dimensional diffraction control elements 40 and 40a, respectively.
[0043]
The slit elements 50 and 50a are disposed near the focal points of the convex lenses 81 and 84, respectively, and remove first-order or higher-order diffracted light components of the diffracted light emitted from the one-dimensional diffraction control elements 40 and 40a (conversely, 0 This is an optical element for extracting the next diffracted light component. Slits 51 and 51a (openings) along the Y direction are formed in the slit elements 50 and 50a. The slits 51 and 51a along the Y direction correspond to the arrangement direction of the individual diffraction control elements 41 and 41a. The slits 51 and 51a allow the 0th-order diffracted light L0 to pass as shown in FIGS. On the other hand, the first-order diffracted light L1 (including both positive and negative first-order diffracted lights L + 1 and L-1) is shielded by the slit elements 50 and 50a. This is because the first-order diffracted light L1 is emitted with an angle ± θ inclined with respect to the 0th-order diffracted light L1 (the sign of the angle θ corresponds to the sign of the first-order diffracted light (+ 1st order or −1st order)).
[0044]
As described above, the one-dimensional diffraction control element 40a controls the switching of the light diffraction state between the 0th order and the 1st order (including ± 1st order) as a whole, so that the diffracted light passes through the slit 51a (0th order light). ) And shielding (in the case of primary light) are switched.
[0045]
The convex lens 82 is an optical element for converting light emitted from the slit element 50 into substantially parallel light.
[0046]
The convex lens 83 is an optical element for condensing the substantially parallel light emitted from the convex lens 82 onto the hologram recording medium M.
[0047]
The convex lens 85 is an optical element for condensing the light emitted from the slit element 50a on the hologram recording medium M. The light emitted from the convex lens 85 is applied to the same portion of the hologram recording medium M as the light emitted from the convex lens 83 to form interference fringes (light brightness and darkness).
[0048]
The hologram recording medium M is a recording medium that records interference fringes due to light emitted from the convex lenses 83 and 84 as a change in refractive index. As a constituent material of the hologram recording medium M, any material can be used regardless of whether it is an organic material or an inorganic material as long as the refractive index changes according to the intensity of light.
[0049]
As an inorganic material, for example, lithium niobate (LiNbO ₃ The photorefractive material whose refractive index changes according to the exposure amount by the electro-optic effect such as) can be used.
[0050]
As the organic material, for example, a photopolymerization type photopolymer can be used. In the photopolymerization type photopolymer, in the initial state, monomers are uniformly dispersed in the matrix polymer. When this is irradiated with light, the monomer is polymerized at the exposed portion. As the polymer is formed, the monomer moves from the surroundings, and the concentration of the monomer changes depending on the location.
[0051]
As described above, by changing the refractive index of the hologram recording medium M according to the exposure amount, interference fringes generated by the interference between the reference light and the signal light can be recorded on the hologram recording medium M as a change in the refractive index.
(Operation of Hologram Recording Device 100)
Hereinafter, recording of data on the hologram recording medium M by the hologram recording apparatus 100 will be described.
[0052]
The laser light emitted from the laser light source 10 is divided into two lights (reference light and signal light) by the half mirror 30 after the beam diameter is expanded in the Y direction by the one-dimensional beam expander 20.
[0053]
The reference light passes through the convex lens 84 and is collected on the hologram recording medium M.
[0054]
The signal light is converged in the X direction by the cylindrical lens 71 and enters the one-dimensional diffraction control element 40. As described above, each individual diffraction control element 41 independently takes two diffraction states (OFF: only the 0th-order diffracted light, ON: only the first-order diffracted light). The number of bits corresponding to the number of control elements 41 (for example, 1088 bits when the number of individual diffraction control elements 41 is 1088) can be expressed.
[0055]
The diffracted light diffracted by the one-dimensional diffraction control element 40 is converged by the convex lens 81 and passes through the slit element 50, so that two intensities (bright and dark) corresponding to two diffraction states (OFF and ON) are obtained. Take. That is, ON and OFF of the individual diffraction control element 41 can be made to correspond to bits 1 and 0.
[0056]
The diffracted light whose diffraction state has been converted into intensity is condensed on the hologram recording medium M via the convex lenses 82 and 83.
[0057]
After the reference light is reflected by the mirror 31 and changed in direction, the reference light is converged in the X direction by the cylindrical lens 72, enters the one-dimensional diffraction control element 40a, and exits as zero-order or first-order diffracted light.
[0058]
That is, when all the ribbons 42 are arranged (hereinafter referred to as all “0”), the reference light is reflected like a mirror from the one-dimensional diffraction control element 40a (in other words, only the zero-order light is reflected). appear). Further, when every other ribbon 42 is shifted by λ / (4 * / COSα) (hereinafter referred to as all “1”, α: incident angle to the one-dimensional diffraction control element 40a), the reference light is used. Becomes the first-order light only after being reflected by the one-dimensional diffraction control element 40a.
[0059]
The 0th-order or 1st-order diffracted light diffracted by the one-dimensional diffraction control element 40a is converged by the convex lens 85 and passes through the slit element 50a. Or shielded. Thus, the reference light can be turned on and off by setting the one-dimensional diffraction control element 40a to all “0” or all “1” by combining the one-dimensional diffraction control element 40a and the slit element 50a. .
[0060]
Thereafter, the reference light is condensed on the hologram recording medium M via the convex lens 85.
[0061]
At this time, since the reference light and the signal light are condensed at substantially the same location of the hologram recording medium M, an interference fringe is formed on the hologram recording medium M, and the refractive index of the hologram recording medium M corresponds to the interference fringe. Change.
[0062]
As described above, the refractive index distribution of the hologram recording medium M is formed corresponding to each binary state of the individual diffraction control elements 41 of the one-dimensional diffraction control element 40, and data can be recorded on the hologram recording medium M. It becomes. For example, when there are 1088 individual diffraction control elements 41, 1088-bit data is recorded by exposing the hologram recording medium M once using the one-dimensional diffraction control element 40.
[0063]
Further, the reference light can be turned ON / OFF by controlling the light diffraction state by the one-dimensional diffraction control element 40a.
[0064]
The hologram recording medium M is subjected to exposure on the hologram recording medium M a plurality of times while shifting the condensing location and the incident direction of the reference light and the signal light, and thereby data having a number of bits that is a multiple of the number of the individual diffraction control elements 41 is obtained. Can be recorded. That is, if the number of the individual diffraction control elements 41 is ON and the number of the individual diffraction control elements 41 is n and the number of exposures is m, n · m-bit data can be recorded on the hologram recording medium M.
(Second Embodiment)
FIG. 6 is a schematic view showing a hologram recording apparatus 200 according to the second embodiment of the present invention.
[0065]
As shown in FIG. 6, the hologram recording apparatus 200 includes a laser light source 10, a two-dimensional beam expander 220, a half mirror 30, a liquid crystal display element 240, a slit element 50a, a cylindrical lens 72, and convex lenses 84 and 85. Information is recorded on and reproduced from the hologram recording medium M.
[0066]
Basically, by using the liquid crystal display element 240 instead of the one-dimensional diffraction control element 40, the convex lenses 81 and 82, and the slit element 50 in the hologram recording apparatus 100, two-dimensionally modulating light, The amount of information that can be recorded at a time can be increased.
[0067]
Along with the use of the liquid crystal display element 240, a two-dimensional beam expander 220 in which a normal concave lens 221 and a convex lens 222 are combined is arranged instead of the one-dimensional beam expander 20.
[0068]
The reason for changing to the two-dimensional beam expander 220 is that all pixels of the liquid crystal display element 240 are irradiated with laser.
[0069]
Since the basic operation of the hologram recording apparatus 200 is not essentially different from that of the hologram recording apparatus 100, description thereof is omitted.
(Third embodiment)
FIG. 7 is a schematic view showing a hologram recording apparatus 300 according to the third embodiment of the present invention.
[0070]
As shown in FIG. 7, the hologram recording apparatus 300 includes a laser light source 10, a one-dimensional beam expander 20, a half mirror 30, one-dimensional diffraction control elements 40 and 40a, slit elements 50 and 50a, and cylindrical lenses 71 and 72. , Convex lenses 81 to 84, 285, and 286, which record and reproduce information on the hologram recording medium M.
[0071]
In the present embodiment, the cylindrical lens 72, the one-dimensional diffraction control element 40a, the convex lens 84, and the slit element 50a are disposed in front of the half mirror 30.
The convex lens 285 converts the laser light that has passed through the slit element 50a into parallel light. The convex lens 286 focuses the laser light (reference light) divided by the half mirror 30 on the hologram recording medium M.
[0072]
In the present embodiment, the laser light is turned on / off by a combination of the one-dimensional diffraction control element 40a and the slit element 50a before the laser light is divided into signal light and reference light by the half mirror 30.
[0073]
Specifically, when the one-dimensional diffraction control element 40a is all “0”, the laser light diffracted by the slit element 50a is focused by the convex lens 84 and then passes through the slit element 50a. Thereafter, the spread laser light is converted into parallel light by the convex lens 285 and applied to the half mirror 30. When the one-dimensional diffraction control element 40a is all “0”, the laser light diffracted by the slit element 50a is only ± first-order light and is blocked by the slit element 50a.
[0074]
Unlike the first and second embodiments, this embodiment cannot irradiate only the signal light to the hologram recording medium M, but it is practically not irradiated with only the signal light in holographic recording / reproduction. There is no hindrance.
[0075]
Since the basic operation of the hologram recording apparatus 300 is not essentially different from that of the hologram recording apparatus 100, description thereof will be omitted.
(Other embodiments)
Embodiments of the present invention are not limited to the above-described embodiments, and can be expanded and modified. The expanded and modified embodiments are also included in the technical scope of the present invention.
[0076]
For example, a general diffraction grating capable of controlling the diffraction state can be used instead of the one-dimensional diffraction control element.
[0077]
As the diffraction grating, various diffraction gratings other than the phase difference method for giving a phase difference to each diffracted light diffracted from the ribbon can be used. For example, a deformable mirror can be used.
[0078]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a hologram recording apparatus and a hologram recording method for recording data onto a hologram recording medium by quickly controlling laser light.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a hologram recording apparatus according to a first embodiment of the present invention.
2 is a top view illustrating a state where the one-dimensional diffraction control element illustrated in FIG. 1 is viewed from above. FIG.
FIG. 3 is a top view illustrating a state where the one-dimensional diffraction control element illustrated in FIG. 1 is viewed from a side surface.
4 is a front view illustrating a state in which the one-dimensional diffraction control element illustrated in FIG. 1 is viewed from the front. FIG.
FIG. 5 is a schematic diagram showing a state in which zero-order diffracted light from a one-dimensional diffraction control element passes and first-order diffracted light is blocked by a slit element.
FIG. 6 is a schematic diagram showing a hologram recording apparatus according to a second embodiment of the present invention.
FIG. 7 is a schematic diagram showing a hologram recording apparatus according to a third embodiment of the present invention.
[Explanation of symbols]
100 Hologram recording device
10 Laser light source
20 One-dimensional beam expander
21 Plano-concave lens
22 Cylindrical lens
30 half mirror
31 mirror
40, 40a One-dimensional diffraction control element
41 Individual diffraction control elements
42 Ribbon
43 Insulating film
44 Counter electrode
45 substrates
50, 50a Slit element
51, 51a Slit
60 One-dimensional light receiving element
71, 72 Cylindrical lens
81-85 Convex lens

Claims (16)

A laser light source for emitting laser light;
A diffraction state switching element that diffracts laser light emitted from the laser light source and that can switch a diffraction state between the first and second diffraction states;
A light shielding element that passes the laser light diffracted by the diffraction state switching element in the first diffraction state and shields the laser light in the second diffraction state;
A light splitting element that splits laser light emitted from the light shielding element into signal light and reference light;
A light modulation element for modulating the signal light emitted from the light splitting element;
A first condensing element that condenses the signal light emitted from the light modulation element on a hologram recording medium;
A second condensing element that condenses the reference light emitted from the light splitting element at substantially the same location as the signal light condensed by the first condensing element. Hologram recording device. 2. The hologram recording apparatus according to claim 1, wherein the diffraction state switching element has first and second phase control elements for controlling a phase difference of light emitted from each of the diffraction state switching elements. 3. The hologram recording apparatus according to claim 2, wherein the emitted light from each of the first and second phase control elements is diffracted light diffracted by the first and second phase control elements. 4. The hologram recording apparatus according to claim 3, wherein each of the first and second phase control elements has a substantially ribbon shape. 5. The hologram recording apparatus according to claim 4, wherein at least one of the first and second phase control elements is displaced by an electrostatic force. The hologram recording apparatus according to claim 1, wherein the light modulation element includes a diffraction control element that emits light by controlling a diffraction state of incident light. The hologram recording apparatus according to claim 1, wherein the light modulation element includes a liquid crystal element. A laser light source for emitting laser light;
A light splitting element that splits laser light emitted from the laser light source into signal light and reference light;
A light modulation element for modulating the signal light emitted from the light splitting element;
A first condensing element that condenses the signal light emitted from the light modulation element on a hologram recording medium;
A diffraction state switching element that diffracts the reference light emitted from the light splitting element and can switch the diffraction state between the first and second diffraction states;
A light shielding element that allows the reference light diffracted by the diffraction state switching element to pass in the first diffraction state and shields in the second diffraction state;
A second condensing element that condenses the reference light emitted from the light shielding element at substantially the same location as the signal light condensed by the first condensing element. Hologram recording device. 9. The hologram recording apparatus according to claim 8, wherein the diffraction state switching element has first and second phase control elements for controlling a phase difference of light emitted from each of the diffraction state switching elements. 10. The hologram recording apparatus according to claim 9, wherein the emitted light from each of the first and second phase control elements is diffracted light diffracted by the first and second phase control elements. The hologram recording apparatus according to claim 10, wherein each of the first and second phase control elements has a substantially ribbon shape. 12. The hologram recording apparatus according to claim 11, wherein at least one of the first and second phase control elements is displaced by an electrostatic force. 9. The hologram recording apparatus according to claim 8, wherein the light modulation element includes a diffraction control element that emits light by controlling a diffraction state of incident light. The hologram recording apparatus according to claim 8, wherein the light modulation element includes a liquid crystal element. A diffraction step of diffracting the laser light emitted from the laser light source in either of the first and second diffraction states capable of switching;
A light shielding step that allows the laser light diffracted in the diffraction step to pass when in the first diffraction state and shields when the laser light is in the second diffraction state;
A light splitting step for splitting the emitted light emitted in the light shielding step into signal light and reference light when passing the laser light in the light shielding step;
A light modulation step for modulating the signal light emitted in the light splitting step when laser light is allowed to pass in the light shielding step;
A first condensing step of condensing the signal light modulated in the light modulation step on a hologram recording medium when the laser light is allowed to pass in the light shielding step;
Secondly, when the laser beam is allowed to pass through in the light shielding step, the reference light divided in the light dividing step is condensed at substantially the same location as the signal light condensed in the first condensing step. And a condensing step. A light splitting step for splitting laser light emitted from the laser light source into signal light and reference light;
An optical modulation step for modulating the signal light divided in the optical division step;
A first condensing step of condensing the signal light modulated in the light modulation step on a hologram recording medium;
A diffraction step of diffracting the reference light split in the light splitting step in either of the first and second diffraction states capable of switching;
A light shielding step for allowing the reference light diffracted in the diffraction step to pass when in the first diffraction state and shielding when in the second diffraction state;
A second condensing step for condensing the reference light at substantially the same location as the signal light collected in the first condensing step when the reference light is allowed to pass in the light shielding step; A hologram recording method comprising:

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