JP6855069B2 - Rewritable hologram recording material, hologram recording / erasing method, and hologram recording device - Google Patents

Description

The present invention relates to rewritable hologram recording materials and recording media. The present invention also relates to a hologram recording / erasing method and a hologram recording device for use in the above method.

Certain substances are known to have good charge transporting ability, and as an application example thereof, there is a photorefractive effect. The photorefractive effect is that the refractive index of a substance changes due to the Pockels effect when irradiated with laser light or the like. Specifically, there is a case where two coherent laser beams are crossed to irradiate the medium. The intersecting beams interfere with each other, forming periodic interference fringes in the medium. In this interference fringe, bright and dark areas appear alternately, and in the bright place, the medium is photoexcited to generate charge carriers, and the generated charge carriers drift from the bright place by the external electric field applied to the medium. And it is trapped in the dark. This results in a periodic charge density distribution in the medium. This periodic charge density distribution induces a periodic change in the index of refraction in the medium via the Pockels effect.

A substance having such a photorefractive effect can utilize the photorefractive effect to perform imaging of distorted objects, real-time holography, supermultiplex hologram recording, 3D display, 3D printer, optical amplification, and optical neural network. It is used in many fields such as non-linear optical information processing including, pattern recognition, optical limiting, and storage of high-density optical data.

However, in a device using the conventional photorefractive effect, a high electric field of several tens of V / μm (corresponding to a voltage of several kV in a device having a thickness of several MV / cm, for example, 100 μm) is applied to the photorefractive element. There is a drawback that there is a high risk of dielectric breakdown in a high electric field.

As a material that overcomes the above drawbacks, photoisomerization (a phenomenon in which a molecule changes to an isomer by absorbing light) can induce a periodic change in the refractive index without an electric field. (A substance has the property of being colored by light irradiation or changing its color tone, and then returning to its original state by heat or light of a wavelength different from the light that caused the coloring or the change in color tone. The development of materials composed of substances with (that) is underway. Here, the substance having the photochromic property usually has a problem in stability and has a drawback that the recorded information is erased in a short time.

Therefore, as a material that overcomes the above drawbacks, a rewritable hologram material composed of a polymer azobenzene liquid crystal or a polymer having a liquid crystal component and a photochromic component is disclosed (Patent Documents 1 and 2).

Further, as a low molecular weight hologram material different from the high molecular weight hologram materials disclosed in Patent Documents 1 and 2, it has a carbazoleazobenzene moiety in its skeleton and has a substituent such as a nitro group or a cyano group at the para position of benzene. A material composed of the introduced low molecular weight compound is disclosed (Patent Document 3). Furthermore, as a material for rewritable hologram displays, carbazole azobenzene (3-[(4-nitrophenyl) azo] -9H-carbazole-9-ethanol (NACzE)) in which the substituent at the para position of benzene is a nitro group is poly. It is disclosed that a material dispersed / dissolved in methyl methacrylate (PMMA) is used as a photorefractive material to record a hologram (Patent Documents 4 and 5, Non-Patent Documents 1, 2 and 3). However, the above-mentioned material in which carbazole azobenzene is dispersed and dissolved has a drawback that the recorded hologram information disappears with the passage of time and lacks memory.

Therefore, as a means for solving the above-mentioned drawbacks, the development of a rewritable hologram material having improved memorability, which comprises a copolymer having carbazoleazobenzene in the side chain and an acrylic polymer such as PMMA as the main chain, has been promoted. ing.

Japanese Patent Publication "Japanese Unexamined Patent Publication No. 2001-265199 (published on September 28, 2001)" Japanese Patent Publication "Japanese Patent Laid-Open No. 2004-252327 (published on September 9, 2004)" Japanese Patent Publication "Japanese Unexamined Patent Publication No. 2014-142393 (published on August 7, 2014)" International Publication "WO2013 / 080883 (published June 6, 2013)" Japanese Patent Publication "Japanese Unexamined Patent Publication No. 2014-248061 (published on December 25, 2014)"

Opt. Mater. Express 2 (8), 1003-1010 (2012) Opt. Express 21 (17), 19880-19884 (2013) J. Phys. Chem. C, 18567-18572 (2015)

However, although the above-mentioned material containing the copolymer has improved memory properties, it has a problem that the photoresponsiveness is low and the light irradiation time required for rising is long.

Further, a material having a good memory property, such as the above-mentioned material made of a copolymer, has a problem that it takes time to erase the recorded hologram information. That is, there is no report that the problem of achieving both responsiveness at the time of recording and memory property and being able to quickly erase the recorded data has been solved. For example, the above-mentioned erasure is usually performed by irradiation with linearly polarized light, but in the above-mentioned erasure, when the hologram information is recorded again after the erasure and the erasure is repeated again, the diffraction efficiency is lowered, and the erasure is said to be the same. It takes time to erase the hologram information, and there is a problem that the time required for re-recording and the response speed at the time of re-recording are lowered.

In order to solve the above problems, the present inventors have conducted diligent research and introduced them into a copolymer in which carbazole azobenzene is introduced into a part of the side chain of an acrylic polymer, and the above-mentioned copolymer. We have found that the photoresponsiveness can be improved while maintaining the memory property by containing the carbazole azobenzene molecule of the same type or different from that of the carbazole azobenzene, and came up with the present invention. Further, the present inventors use circular polarization to erase the recorded hologram information, so that the diffraction efficiency is lowered even when the hologram information is recorded again after the erasure and then erased again. The present invention was conceived by finding that the time required for erasing can be shortened and the time required for re-recording can be shortened.

The present invention includes the rewritable hologram recording material, the recording medium, the method of recording / erasing the hologram, and the hologram recording apparatus according to the following [1] to [14].
[1] Containing a copolymer obtained by introducing carbazoleazobenzene into a part of the side chain of an acrylic polymer, and a carbazoleazobenzene molecule of the same type or different from that of the carbazoleazobenzene introduced into the copolymer. A rewritable hologram recording material characterized by.
(Here, carbazoleazobenzene is represented by the following formula (1).)

[2] The rewritable hologram recording material according to [1], wherein the carbazole azobenzene is carbazole azobenzene in which X in the above formula (1) is a cyano group, a nitro group or a methoxy group.
[3] The rewritable hologram recording material according to [1] or [2], wherein the carbazole azobenzene introduced into the side chain of the copolymer and the carbazole azobenzene molecule are of the same type.
[4] The rewritable hologram recording according to any one of [1] to [3], wherein at least one of the acrylic polymers is selected from the group consisting of polymethylmethacrylate, polyethylmethacrylate and polymethylacrylate. material.
[5] The total of the carbazole azobenzene-derived group and the carbazole azobenzene molecule contained in the copolymer with respect to the total weight of the copolymer and the carbazole azobenzene molecule contained in the rewritable hologram recording material. The rewritable hologram recording material according to any one of [1] to [4], wherein the molar concentration of the above is 5 × 10 ^-4 mol / g or more and 2.0 × 10 ^{-3 mol / g or less.}
[6] Any one of [1] to [5], wherein the molar ratio of the carbazole azobenzene molecule to the group derived from carbazole azobenzene contained in the copolymer is 0.5 or more and 2.0 or less. Rewritable hologram recording material described in 1.
[7] The rewritable hologram recording material according to any one of [1] to [6], wherein the copolymer has a weight average molecular weight of 10,000 or more and 200,000 or less.
[8] A recording medium having a hologram recording element.
The hologram recording element is a recording medium containing the rewritable hologram recording material according to any one of [1] to [7].
[9] In a hologram recording element containing a rewritable hologram recording material, a striped pattern on a spatial light modulator (SLM) can be formed by using a single light beam of laser light, or by interfering object light and reference light. (2 light beam interference) to form interference fringes in the hologram recording element, and to record the hologram on the hologram recording element and to irradiate the hologram recording element with polarized light to generate the hologram. A hologram recording / erasing method that includes a process of erasing.
The rewritable hologram recording material is a copolymer obtained by introducing carbazoleazobenzene into a part of the side chain of an acrylic polymer, and
For a hologram recording device made of a material further containing a carbazole azobenzene molecule of the same type or a different type as the carbazole azobenzene introduced into the copolymer.
A hologram recording / erasing method, characterized in that at least the step of erasing the hologram is performed by irradiation with circularly polarized light.
[10] The method for recording / erasing a hologram according to [9], wherein the object light and the reference light in the recording step are circularly polarized light.
[11] The method according to [9] or [10], further comprising a step of reproducing the recorded hologram by irradiating the hologram recording element on which the hologram is recorded with polarized light having the same phase as the reference light. Hologram recording / erasing method.
[12] The method for recording / erasing a hologram according to [11], wherein in the step of reproducing the recorded hologram, the polarized light applied to the recording element on which the hologram is recorded is circularly polarized light.
[13] A hologram recording device for using the hologram recording / erasing method by two luminous flux interference in order to perform the hologram recording / erasing method according to any one of [9] to [12]. ,
A hologram recording apparatus comprising a mechanism for irradiating the hologram recording element with circular polarization through at least the erasing step.
[14] The hologram recording device according to [13], wherein the mechanism for irradiating the circularly polarized light is a λ / 4 plate.

The rewritable hologram recording material of the present invention has excellent optical responsiveness while maintaining excellent memory properties capable of holding recorded data for a long time, or further improving memory properties, and is capable of recording holograms. It has the effect of shortening the rise time.

Further, the hologram recording / erasing method of the present invention can shorten the time required for erasing the hologram, and prevent a decrease in response speed and diffraction efficiency in re-recording after the erasure, which is usually decreased. It has the effect of being able to.

In Examples 1 to 3 and Comparative Examples 1 and 2, the writing light: 300 mW / 532 nm, the readout light (probe light): 1 mW / 640 nm, and the striped pattern on the spatial light modulator (SLM) is one light beam. The relationship between the diffraction efficiency and the time from the start of light irradiation is shown, which is the result of measuring the rise of the diffracted light when the rewritable hologram recording material is irradiated with laser light. It is a figure. In Examples 1 to 3 and Comparative Examples 1 and 2, the writing light: 300 mW / 532 nm, the readout light (probe light): 1 mW / 640 nm, and the striped pattern on the spatial light modulator (SLM) is one light beam. The relationship between the diffraction efficiency and the time from the start of light irradiation when a long time has passed since the start of light irradiation, which is the result of measuring the rise of the diffracted light when the rewritable hologram recording material is irradiated with laser light. It is a figure which shows. In Examples 1 to 3 and Comparative Examples 1 and 2, since the lattice spacing is wider than the lattice thickness, Ramannas diffraction occurs, and the theoretical maximum diffraction efficiency is 16%. In Example 4, a diffraction grating was prepared using two light beam interferences at write light (object light and reference light): 25 mW / 532 nm and readout light (probe light): <1 mW / 632.8 nm, and diffraction thereof. It is a figure which shows the relationship between the time from the first light irradiation and the diffraction efficiency which is the result of having measured the time profile of the diffraction intensity from a grating. In Example 4, since the lattice spacing is narrow with respect to the lattice thickness, Bragg diffraction occurs, and the theoretical maximum diffraction efficiency is 100%. In Example 5, a diffraction grating was prepared using two light beam interferences at write light (object light and reference light): 25 mW / 532 nm and readout light (probe light): <1 mW / 632.8 nm, and diffraction thereof. It is a figure which shows the relationship between the time from the first light irradiation and the diffraction efficiency which is the result of having measured the time profile of the diffraction intensity from a grating. In Example 5, since the lattice spacing is narrow with respect to the lattice thickness, Bragg diffraction occurs, and the theoretical maximum diffraction efficiency is 100%. In Comparative Example 3, a diffraction grating was prepared using two light beam interferences at write light (object light and reference light): 25 mW / 532 nm and readout light (probe light): <1 mW / 632.8 nm, and diffraction thereof. It is a figure which shows the relationship between the time from the first light irradiation and the diffraction efficiency which is the result of having measured the time profile of the diffraction intensity from a grating. In Comparative Example 3, since the lattice spacing is narrower than the lattice thickness, Bragg diffraction occurs, and the theoretical maximum diffraction efficiency is 100%. In Comparative Example 4, a diffraction grating was prepared using two light beam interferences at write light (object light and reference light): 25 mW / 532 nm and readout light (probe light): <1 mW / 632.8 nm, and diffraction thereof. It is a figure which shows the relationship between the time from the first light irradiation and the diffraction efficiency which is the result of having measured the time profile of the diffraction intensity from a grating. In Comparative Example 4, since the lattice spacing is narrow with respect to the lattice thickness, Bragg diffraction occurs, and the theoretical maximum diffraction efficiency is 100%. It is a figure which shows the schematic structure of the hologram recording apparatus of this invention.

[Embodiment 1: Rewritable hologram recording material]
The rewritable hologram recording material according to the first embodiment of the present invention is introduced into a copolymer obtained by introducing carbazoleazobenzene (NACzE) into a part of a side chain of an acrylic polymer, and the above-mentioned copolymer. It is characterized by containing a carbazole azobenzene molecule of the same type or different from that of the above carbazole azobenzene.

In addition, in this specification, carbazole azobenzene other than carbazole azobenzene introduced into the copolymer, which is not introduced into the copolymer and is contained in the rewritable hologram recording material of the present invention in the form of a molecule. Is also referred to as a "carbazole azobenzene molecule".

The copolymer and the carbazole azobenzene molecule contained in the rewritable hologram recording material of the present invention have photochromic properties. Since the copolymer and the carbazole azobenzene molecule have photochromic properties, the entire rewritable hologram recording material of the present invention also has photochromic properties.

In the above-mentioned copolymer, the component derived from the above-mentioned carbazole azobenzene constitutes a part of the side chain of the above-mentioned copolymer. The above-mentioned carbazole azobenzene may be one kind or two or more kinds.

The copolymer obtained by introducing carbazoleazobenzene into a part of the side chain of the acrylic polymer in the rewritable hologram recording material of the present invention (hereinafter, also referred to as "copolymer A in the present invention") has the following formula (hereinafter, also referred to as "copolymer A in the present invention"). As shown in 2), it has a structure in which carbazoleazobenzene is introduced into a part of the side chain of the acrylic polymer.

The acrylic polymer constituting the copolymer A in the present invention is a polymer obtained by polymerizing an acrylic acid ester or a methacrylic acid ester as a monomer (hereinafter, also referred to as “acrylic molecule”). Is. The monomer is not particularly limited, and examples thereof include methyl acrylate (MA), methyl methacrylate (MMA), and ethyl methacrylate (EMA). That is, examples of the acrylic polymer constituting the copolymer in the present invention include polymethylacrylate (PMA), polymethylmethacrylate (PMMA), and polyethylmethacrylate (PEMA). The acrylic polymer constituting the copolymer in the present invention may be a polymer obtained by polymerizing one kind of monomer or a copolymer obtained by polymerizing two or more kinds of monomers.

The carbazoleazobenzene (hereinafter, also referred to as “carbazoleazobenzene molecule”) introduced in the side chain of the copolymer A in the present invention or contained in the rewritable hologram recording material of the present invention in the form of a molecule , It has a skeletal structure represented by the following formula (1).

The carbazoleazobenzene may have a skeletal structure represented by the above formula (1) and is not particularly limited. For example, X in the above formula (1) is a nitro group (-NO ₂ ) or a cyano group (-NO 2). Examples thereof include carbazoleazobenzene having a structure of -CN), a methoxy group (-OCH ₃ ), an amino group (-NH ₂ ), and a hydroxy group (-OH), of which X is a nitro group, a cyano group or a cyano group. Carbazole azobenzene having a structure of a methoxy group is preferable, and carbazole azobenzene having a structure in which X is a cyano group or a methoxy group is more preferable. The carbazole azobenzene may be of one kind or two or more kinds.

Further, the carbazole azobenzene introduced into the side chain of the copolymer in the present invention and the carbazole azobenzene (carbazole azobenzene molecule) contained in the rewritable hologram recording material of the present invention in the form of a molecule are of the same type. It may be present or different, but it is preferable that they are of the same type from the viewpoint of compatibility between the copolymer and the carbazoleazobenzene molecule in the rewritable hologram recording material of the present invention. Therefore, in the rewritable hologram recording material of the present invention, the carbazole azobenzene introduced into the side chain of the copolymer in the present invention and the carbazole azobenzene molecule are particularly preferably one kind of carbazole azobenzene.

In the rewritable hologram recording material of the present invention, the group derived from carbazole azobenzene contained in the copolymer and the group derived from the carbazole azobenzene with respect to the total weight of the copolymer and the carbazole azobenzene molecule contained in the rewritable hologram recording material. The total molar concentration with the carbazole azobenzene molecule is 5 × 10 ^-4 mol / g or more, 2.0 × 10 ^-3 mol / g or less, and more preferably 7 × 10 ^-4 mol / g or more. It is 1.5 × 10 ^-3 mol / g or less, more preferably 1 × 10 ^-3 mol / g or more, and 1.3 × 10 ^-3 mol / g or less.

In the rewritable hologram recording material of the present invention, the molar ratio of the carbazoleazobenzene molecule to the group derived from carbazoleazobenzene contained in the copolymer is 0.5 or more and 2.0 or less, preferably 0. It is 7 or more and 1.6 or less, and more preferably 0.9 or more and 1.2 or less.

The weight average molecular weight (Mw) of the copolymer in the present invention is preferably 10,000 to 100,000, more preferably 20,000 to 100,000. Setting the weight average molecular weight of the copolymer in the above range to the above range means that the rewritable hologram recording material of the present invention is formed into a film having a preferable thickness, which will be described later, which is suitable as the rewritable hologram recording material. Is preferable.

Further, the value of the dispersion degree (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the molecular weight distribution of the copolymer in the present invention is smaller in terms of the uniformity of the rewritable hologram recording material of the present invention. Specifically, the value of Mw / Mn is preferably 1 to 3.

The rewritable hologram recording material of the present invention is preferably in the form of a film (thin film). Further, the film thickness is more preferably 10 μm to 200 μm, and further preferably 20 μm to 100 μm.

The rewritable hologram recording material of the present invention may contain various additives in addition to the above-mentioned copolymer and the above-mentioned carbazole-azobenzene molecule. The additive may be any additive that can be generally used in the hologram recording material, and is not particularly limited. Examples of the additive include a (light) sensitizer, a non-linear optical dye, a plasticizer, a photosensitive dye, and the like.

The reason why the rewritable hologram recording material containing the copolymer is excellent in memory property is that the carbazole azobenzene introduced into the side chain of the copolymer has a more limited orientation than the free carbazole azobenzene molecule. Therefore, it is considered that the photo-oriented carbazole azobenzene is difficult to return to the orientation before light irradiation even after a lapse of time. However, we have to wait for more detailed operation elucidation in the future.

Since the rewritable hologram recording material of the present invention contains the copolymer and the carbazole azobenzene molecule of the present invention, the memory property is further improved, and in addition, the photoresponsiveness is improved, and the rise of hologram recording Time is reduced.

The reason why the above-mentioned memory property is further improved is that the photo-oriented carbazole azobenzene molecule forms a mesophase in which the carbazole azobenzene introduced into the side chain of the copolymer and the free carbazole azobenzene molecule interact with each other. It is considered that the energetically stable state (pinning effect) prevents the photoaligned carbazoleazobenzene from returning to the orientation before light irradiation with the passage of time.

Further, the degree of freedom of orientation of the carbazole azobenzene molecule is larger than that of the carbazole azobenzene introduced into the side chain of the copolymer, and the photoorientation of the carbazole azobenzene molecule is introduced into the side chain of the copolymer by light irradiation. It is generated in preference to the carbazole azobenzene produced. From the above items, it is considered that the carbazole azobenzene molecules are photoaligned even with short-time light irradiation, so that the hologram recording of the rewritable hologram recording material of the present invention starts up at high speed. However, we have to wait for more detailed operation elucidation in the future.

[Manufacturing method of rewritable hologram recording material]
The method for producing the rewritable hologram recording material of the present invention can use a method known to those skilled in the art and is not particularly limited. The rewritable hologram recording material of the present invention can be produced, for example, by a method including the following steps (1) and (2). The operations in each step shown below can be carried out by a method known to those skilled in the art.

<Step (1) Preparation of copolymer>
The method for preparing a copolymer obtained by introducing carbazoleazobenzene into a part of the side chain of the acrylic polymer contained in the rewritable hologram recording material of the present invention is not particularly limited, and includes, for example, the following steps. The method can be mentioned.

Step (i): Dissolve carbazoleazobenzene in tetrahydrofuran (THF), stir while cooling to 0 ° C., and add N, N-dimethyl-4-aminopyridine (DMAP) and triethylamine;
Step (ii): 1 mL each of acrylate or methacrylic acid salt was added dropwise to the solution obtained in step (i) at a temperature of 0 ° C. or lower, for example, every 15 minutes four times to add a reaction mixture. Step of returning to room temperature with stirring and stirring overnight;
Step (iii): A step of removing the solvent from the solution obtained in step (ii) by drying under reduced pressure and dissolving the obtained crude product in chloroform;
Step (iv): The chloroform solution obtained in step (iii) was washed several times with saturated aqueous sodium hydrogen carbonate solution and distilled water, dried over anhydrous magnesium sulfate, and the compound of carbazoleazobenzene- (meth) acrylic acid was prepared. Obtaining process;
Step (v): The compound of carbazoleazobenzene- (meth) acrylic acid obtained in step (iv) is dissolved in dry dimethylfuran (DMF), further acrylic acid or methacrylic acid, and azoisobutynitrile as a polymerization initiator. (AIBN) is added, the copolymerization reaction is started, freeze-deaeration is performed, and then the mixture is stirred at 60 ° C. for 15 hours, the liquid temperature is returned to room temperature, and the copolymerization reaction is stopped;
Step (vi): The copolymer is reprecipitated from the solution obtained in step (v) in which the copolymer obtained by introducing carbazoleazobenzene into a part of the side chain of the acrylic polymer is dissolved. A step of recovering the copolymer by allowing, filtering, and drying.

<Step (2): Preparation of rewritable hologram recording material>
The rewritable hologram recording material of the present invention can be prepared by using the copolymer prepared in the step (1) and the carbazoleazobenzene molecule. The preparation method is not particularly limited, but for example, the following method can be used.

Step (vi): Each component of the rewritable hologram recording material of the present invention containing the copolymer and the carbazole azobenzene molecule obtained in the step (vi) is dissolved in a solvent having a boiling point of 100 ° C. or higher and coated. Step to obtain solution;
Step (viii): A step of preparing a thin-film rewritable hologram recording material by applying the coating solution obtained in the step (vii) onto a substrate and removing the solvent. Here, the method for removing the solvent is not particularly limited, but for example, a method for obtaining a cast film on a plate material, specifically, a method in which a solution in which each component is dissolved is cast on a glass plate. Then, the solvent is evaporated at room temperature, followed by natural drying overnight, and then dried under reduced pressure at a high temperature using a vacuum dryer or the like to further evaporate the solvent.

After distilling off the solvent, for example, spacers (for example, polyimide, thickness: 50 μm) are placed at the four corners, and then another glass base material is placed on top, and a vacuum is applied while applying appropriate heat (temperature). A sandwich-type rewritable hologram recording material can also be prepared by crimping with a press machine.

[Embodiment 2: Recording Medium]
The recording medium according to the second embodiment of the present invention is a recording medium having a hologram recording element, and the hologram recording element contains the rewritable hologram recording material according to the first embodiment of the present invention. .. Specifically, the recording medium according to the second embodiment of the present invention is a hologram formed by forming a sheet-like film of the rewritable hologram recording material according to the first embodiment of the present invention by sandwiching it between transparent plates such as glass. Contains a recording element. Therefore, the recording medium of the present invention contains a rewritable hologram recording material having excellent both photoresponsiveness and memory properties as a hologram recording element, has a short rise time when recording a hologram, and is capable of recording a hologram. Can be stored for a long time. As a method for manufacturing a recording medium of the present invention, a method common to those skilled in the art, for example, a die or a doctor, except that the rewritable hologram recording material according to the first embodiment of the present invention is used as the hologram recording element. It can be manufactured by a sheet forming method using a blade or the like.

[Embodiment 3: Hologram recording / erasing method]
In the hologram recording / erasing method according to the third embodiment of the present invention, one light beam of laser light is applied to a striped pattern on a spatial light modulator (SLM) in a hologram recording element containing a rewritable hologram recording material. By using, or by interfering with interfering object light and reference light (two-beam interference), interference fringes are formed in the hologram recording element, and the hologram is recorded on the hologram recording element by the step of recording the hologram and the polarization irradiation. A hologram recording / erasing method including a step of erasing the hologram, wherein the rewritable hologram recording material is a copolymer obtained by introducing carbazoleazobenzene into a part of a side chain of an acrylic polymer, and the above. A feature is that at least a step of erasing the hologram is performed by irradiation with circular polarization on a hologram recording element made of a material further containing a carbazole azobenzene molecule of the same type or a different type as the carbazole azobenzene introduced into the copolymer. And.

The acrylic polymer may be one kind or two or more kinds.

The above-mentioned carbazole azobenzene may be one kind or two or more kinds. Further, the carbazole azobenzene molecule may also be of one kind or two or more kinds.

In the hologram recording / erasing method of the present invention, the spatial light modulator (SLM) is a space such as the amplitude, phase, and polarization of light from a light source by arranging a plurality of small elements called "light modulators" in two dimensions. It is a device that modulates light by electrically controlling the distribution of light. Examples of the spatial light modulator (SLM) include products of Holoeye and Hamatsu Photonics.

In the method for recording / erasing a hologram of the present invention, erasing the recorded hologram is a recording in which the hologram is recorded with circular polarization having the same phase as either the object light or the reference light used for recording the hologram. This is done by irradiating the element.

In the hologram recording / erasing method of the present invention, the rewritable hologram recording material is introduced into a copolymer obtained by introducing carbazoleazobenzene into a part of the side chain of the acrylic polymer and the side chain of the copolymer. It is a hologram recording element made of a material further containing a carbazole azobenzene molecule of the same type or different type as the above-mentioned carbazole azobenzene, that is, a rewritable hologram recording material according to the first embodiment of the present invention.

Regarding the copolymer obtained by introducing carbazole azobenzene into a part of the side chain of the acrylic polymer described above and the carbazole azobenzene molecule, the copolymer and carbazole in the rewritable hologram recording material according to the first embodiment of the present invention. It can be a copolymer and molecule similar to the azobenzene molecule.

Further, the copolymer obtained by introducing carbazoleazobenzene into a part of the side chain of the acrylic polymer described above is prepared by the step described in step (1) in the above [Method for manufacturing rewritable hologram recording material]. Can be done. Further, the rewritable hologram recording material containing the copolymer obtained by introducing carbazoleazobenzene into a part of the side chain of the acrylic polymer and the carbazoleazobenzene molecule described above is described in the above [Method for producing rewritable hologram recording material]. Can be manufactured according to the method described in.

In the hologram recording / erasing method of the present invention, at least the step of erasing the hologram is performed by irradiation with circular polarization to shorten the time required for erasing the hologram, and the response speed and diffraction in the re-recording after the erasing. It is possible to prevent a decrease in efficiency.

When the recorded hologram is erased by irradiation with linearly polarized light, the orientation of the photochromic molecule or group in the hologram recording material is fixed by the irradiation with linearly polarized light for erasing, and the erasing and re-recording are performed. By repeating this, the diffraction efficiency gradually decreases, the response speed decreases, and it is considered necessary to apply light irradiation or heat for a long time in order to make the state re-recordable.

On the other hand, when the recorded hologram is erased by irradiation with circular polarization, the orientation of the photochromic molecule or group in the hologram recording material is randomized and the orientation is not fixed. Therefore, the diffraction as described above is performed. It is considered that it is possible to prevent a decrease in efficiency and a decrease in response speed and shorten the time until re-recording becomes possible. However, we have to wait for more detailed operation elucidation in the future.

In the hologram recording / erasing method of the present invention, it is preferable that not only the hologram is erased but also the hologram is recorded by irradiation with circularly polarized light. Recording a hologram by irradiating circularly polarized light is brighter and clearer because the diffraction efficiency can be improved about 2 to 5 times as compared with recording a hologram by irradiating linearly polarized light at the same time. It is preferable in terms of being able to record a simple hologram.

Further, the method for recording / erasing a hologram of the present invention may include a step of reproducing the recorded hologram. The step of reproducing the recorded hologram is performed by irradiating the recording element on which the hologram is recorded with reading light (polarized light) having the same phase as the reference light. The reading light is preferably circularly polarized light. The number of diffraction points of the diffracted light representing the image of the hologram generated in the above-mentioned reproduction step is confirmed multiple times when linearly polarized light is used, whereas only one is confirmed when circularly polarized light is used. The intensity of the diffracted light is also higher when circularly polarized light is used. Therefore, it is preferable that the read light is circularly polarized light in terms of making the reproduced hologram brighter and clearer.

[Embodiment 4: Hologram recording device]
The hologram recording device according to the fourth embodiment of the present invention is a hologram recording device for using the hologram recording / erasing method by two light beam interference in order to perform the hologram recording / erasing method according to the third embodiment of the present invention. At least in the erasing step, the hologram recording element is provided with a mechanism for irradiating the hologram recording element with circular polarization through the circular polarization element.

The hologram recording apparatus of the present invention is usually used in the field to which the present invention belongs, except that the hologram recording device is provided with a mechanism for irradiating the hologram recording element with circular polarization through a circular polarization element, at least in the step of erasing the recorded hologram. It can be a hologram recording device similar to the hologram recording device to be used.

That is, the hologram recording device of the present invention irradiates a hologram recording element made of a rewritable hologram recording material, the hologram recording element with coherent object light and reference light, and interference fringes in the hologram recording element. A mechanism for forming the hologram and recording the hologram, and a mechanism for erasing the hologram by irradiating the recording element on which the hologram is recorded with circular polarization. Further, the hologram recording apparatus of the present invention may further include a mechanism for reproducing the hologram recorded by irradiating the recording element on which the hologram is recorded with reading light.

The mechanism for erasing the recorded hologram includes a member for converting a linearly polarized laser light source or the like into circularly polarized light to obtain circularly polarized light. The member for obtaining the circular polarization is not particularly limited, and examples thereof include a λ / 4 plate (1/4 wave plate) and a retardation plate. From the viewpoint of ease of installation, the λ / 4 plate is used. preferable.

Further, the hologram recording device of the present invention may also include a member for obtaining circularly polarized light with respect to the hologram recording element in the mechanism for recording the hologram. As the member for obtaining circular polarization in the mechanism for recording the hologram, the same member as the member for obtaining circular polarization in the mechanism for erasing the recorded hologram can be used.

Further, the hologram recording device of the present invention may include a mechanism for reproducing the recorded hologram by irradiating the recording element on which the hologram is recorded with reading light (polarized light). Furthermore, in the mechanism for reproducing the recorded hologram, it is preferable to include a member for obtaining circularly polarized light as the reading light. As the member for obtaining circular polarization in the mechanism for reproducing the recorded hologram, the same member as the member for obtaining circular polarization in the mechanism for erasing the recorded hologram can be used.

As each member such as a member that irradiates light in each of the above-mentioned mechanisms, a general member in the field to which the present invention belongs can be used.

Examples of the mechanism for recording a hologram in the hologram recording device of the present invention include a mechanism for performing two-luminous flux interference using linearly polarized light or circularly polarized light.

Examples of the mechanism for erasing the recorded hologram in the hologram recording device of the present invention include a mechanism for irradiating one light flux of circularly polarized light.

Examples of the mechanism for reproducing the recorded hologram in the hologram recording apparatus of the present invention include a mechanism for irradiating one luminous flux with linearly polarized light or circularly polarized light.

Here, the configuration of the hologram recording device of the present invention will be specifically described with reference to FIG. 7. FIG. 7 is a diagram showing a schematic configuration of the hologram recording device of the present invention.

The hologram recording / reproducing / erasing device, which is an example of the hologram recording device of the present invention, irradiates the holographic display device (Sample) for recording and displaying a hologram image, and the holographic display device with object light and reference light. It is mainly composed of a recording means (erasing means) for recording a hologram image and a reproducing means for reproducing the hologram image recorded by the recording means by irradiating the holographic display device with probe light. In addition, in this specification, "means" is intended as "device" or "mechanism".

The recording means for recording the hologram image is a laser oscillator 1 that oscillates a laser, a first fixed mirror 2 that reflects a laser beam oscillated from the laser oscillator 1, and a laser that is reflected by the first fixed mirror 2. The first half-wave plate 3 arranged on the optical axis of the beam and the laser beam passing through the first half-wave plate 3 are divided into the first and second polarized light of p-polarized light and s-polarized light. A beam splitter 4 as a laser beam, a second half-wave plate 5 arranged on the optical axis of the first polarized laser beam, a 1/4 wave plate 6, and the second half-wave plate and the first In the recording means for recording the hologram image, the second fixed mirror includes a second fixed mirror 7 that reflects the first polarized laser beam that is circularly polarized through the 1/4 wave plate 6 of the above. The circularly polarized first polarized laser beam reflected by No. 7 is applied to the holographic display device (Sample) as object light. Further, the recording means for recording the hologram image passes through the second 1/4 wave plate 8 and the second 1/4 wave plate 8 on the optical axis of the second polarized laser beam and is circularly polarized. In the recording means for recording the hologram image, which includes the third fixed mirror 9 for reflecting the second polarized laser beam, the circularly polarized second second reflected by the third fixed mirror 9. A polarized laser beam is applied to the holographic display device (Sample) as reference light. That is, the laser beam oscillated from the laser oscillator 1 is divided into a circularly polarized first polarized laser beam (object light) and a circularly polarized second polarized laser beam (reference light).

Then, the object light is irradiated to the holographic display device together with the reference light, and the spatial information of the object light is recorded in the holographic display device with the spatial intensity distribution and the phase distribution included in the object light as interference fringes.

The reproduction means for reproducing the recorded hologram image is a laser oscillator 10 that oscillates a laser, a half-wave plate 11 for probe light arranged on the optical axis of the laser beam oscillated from the laser oscillator 10, and probe light. It is composed of a fourth fixed mirror 12 that reflects a laser beam that has passed through the half-wave plate 11. The laser beam oscillated from the laser oscillator 10 is converted into p-polarized light by the probe light half-wave plate 11 and reflected by the fourth fixed mirror 12. Then, the spatial information written (recorded) by the recording means is read out as a hologram image by the p-polarized probe light and reproduced.

When erasing the hologram, the mechanical shutter closes to block the object light, and the circularly polarized reference light is used as the erasing light. Further, the object light and the reference light of the hologram image for overwriting to be written next may be used as the erasing light.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

[A: Rewritable hologram recording material]
[Manufacturing Example 1]
Carbazole azobenzene (CACzE) with a cyano group coordinated at the para position of the benzene ring (see the left figure of the scheme below) was introduced into a part of the side chain of polymethylmethacrylate (PMMA) according to the following scheme. A coalescence (Poly (CACzE-MMA)) (see the figure to the right of the scheme below) was prepared.

The specific method is as follows.

-Synthesis of acrylic acid-2- [3- (4-cyano-phenylazo) -carbazole-9-yl] -ethyl ester (CACzE-MMA) (see central diagram of the above scheme) CAZE 1.97 g (5.79 mmol) Was dissolved in 80 mL of THF, stirred while cooling to 0 ° C., and 0.042 g (0.34 mmol) of DMAP and 1.26 g (12.45 mmol) of triethylamine were added. 1 mL (12.36 mmol) of acryloyl chloride was added dropwise thereto every 15 minutes while keeping the temperature below 0 ° C. The reaction mixture was returned to room temperature (around 20 to 25 ° C.) with stirring, and stirred overnight. After completion of stirring, the solvent was removed from the reaction mixture under reduced pressure, and the obtained crude product was dissolved in chloroform. This was washed several times with saturated aqueous sodium hydrogen carbonate solution and distilled water, and dried over anhydrous magnesium sulfate. Then, suction filtration was performed, and the solvent was distilled off from the filtrate under reduced pressure to obtain an orange powder (yield 87.6%).

The obtained orange powder was subjected to NMR measurement (using a nuclear magnetic resonance apparatus AV-300) to identify the molecular structure. As a result, it was confirmed that CACzE-MMA was synthesized.
NMR measurement: solvent used CDCl ₃ , magnetic field 300 MHz
Measurement results: 8.73 (bs, 1H, carbazole ring), 8.16 (m, 2H, carbazole ring), 8.02 (m, 2H, PhCN ring), 7.82 (m, 2H, PhCN ring), 7.55 (m, 3H, carbazole ring) ring), 7.32 (m, 1H, carbazole ring), 4.00-4.82 (m, 4H, CH ₂ CH ₂ O), 3.47-3.99 (m, 3H _{, COOCH 3} ), 1.71-2.00 (m, 3H, CH ₃₎ ) ppm].

-Synthesis of Poly (CACzE-MMA) 0.5 g of CAZE-MMA was dissolved in 20 ml of dry DMF, and 1.17 g of MMA and 0.03 g of AIBN were added to this solution. In order to remove oxygen in this mixed solution, freezing and degassing was performed four times using liquid nitrogen. After freezing and deaeration, the mixture was stirred at 60 ° C. for 15 hours, the liquid temperature was returned to room temperature (20 to 25 ° C.), and the copolymerization reaction was stopped. The obtained DMF solution was added dropwise to 500 ml of methanol, and the copolymer was reprecipitated and collected by filtration. This operation was repeated again (twice in total) and dried to obtain 0.81 g (yield 66.4%) of the copolymer.

The glass transition temperature of the copolymer obtained by DSC measurement was 103 ° C., the weight average molecular weight was 18,660 g / mol and the dispersity was 1.58 as measured by GPC. The DSC measurement was performed using a DSC2920 manufactured by TA Instruments, and the GPC measurement was performed using a Showa Denko GPC KF-805 manufactured by Showa Denko.

Here, a cyano group coordinated at the para position of the benzene ring is prepared, but as described above, as the substituents coordinated at the para position of the benzene ring, other than the cyano group (-CN), A nitro group (-NO ₂ ), a methoxy group (-OCH ₃ ), an amino group (-NH ₂ ), a hydroxy group (-OH) and the like can be used. As the carbazole azobenzene, carbazole azobenzene having a structure in which the substituent is a nitro group, a cyano group or a methoxy group is preferable, and carbazole azobenzene having a structure in which the substituent is a cyano group or a methoxy group is more preferable. The carbazole azobenzene may be of one kind or two or more kinds.

Further, here, polymethylmethacrylate (PMMA) was used as the acrylic polymer, but as described above, one or more kinds of acrylic polymers such as polyethyl methacrylate (PEMA) and polymethylacrylate (PMA) are used. You can also do it.

[Example 1]
[Preparation of rewritable hologram recording material]
Poly (CACzE-MMA) obtained in Production Example 1 and CACzE were mixed at a weight ratio of 50: 5, and the obtained mixture was dissolved in THF to obtain a cast solution. The cast solution was cast on a petri dish (product name: TOP glass petri dish) and then left at room temperature (25 ° C.) for 48 hours to evaporate the solvent (THF) to obtain a uniform film. Subsequently, the uniform membrane was air-dried overnight, and then dried under reduced pressure in a vacuum dryer at a temperature of about 80 ° C. to further evaporate the solvent (THF). After that, spacers (for example, polyimide, thickness: 50 μm) are placed at the four corners of the obtained film, and then another glass base material (glass plate (product name: Tempax heat-resistant glass)) is placed on it. A sandwich-type rewritable hologram recording material 1 having a uniform film thickness was prepared by pressure-bonding with a vacuum press while applying appropriate heat (temperature). As a result of measuring the film thickness of the rewritable hologram recording material 1 using a micrometer, the film thickness was 80 μm.

Further, in the obtained rewritable hologram recording material 1, the total molar concentration of the group derived from carbazole azobenzene contained in the copolymer and the carbazole azobenzene molecule was 9.7 × 10 ^-4 mol / g. Met. The molar ratio of the carbazole azobenzene molecule to the group derived from carbazole azobenzene contained in the copolymer was 0.38.

[Measurement of rise speed and memory]
The obtained rewritable hologram recording material is used as a hologram recording element, and a hologram recording device is used to irradiate light for 20 seconds under the following conditions to record the hologram, and the diffraction efficiency is measured by a photo detector. Was measured using. FIG. 1 shows the relationship between the time after the start of light irradiation and the diffraction efficiency. Further, FIG. 2 shows the time course of the diffraction efficiency and the holding characteristic (memory characteristic) of the recorded hologram.
-Laser used under measurement conditions: 25 mW / 532 nm
Object light, reference light: wavelength 532 nm, intensity 0.535 W / cm ² .

[Example 2]
A rewritable hologram recording material 2 was prepared in the same manner as in Example 1 except that Poly (CACzE-MMA) obtained in Production Example 1 and CACzE were mixed at a weight ratio of 50:10, and a film thereof was prepared. The thickness was measured. Further, using the rewritable hologram recording material 2, the diffraction efficiency was measured by the same method as in Example 1. The relationship between the time after the start of light irradiation and the diffraction efficiency and memory characteristics is shown in FIGS. 1 and 2.

The film thickness of the rewritable hologram recording material 2 was 80 μm. In the obtained rewritable hologram recording material 2, the total molar concentration of the group derived from carbazole azobenzene contained in the copolymer and the carbazole azobenzene molecule was 1.1 × 10 ^-3 mol / g. It was. The molar ratio of the carbazole azobenzene molecule to the group derived from carbazole azobenzene contained in the copolymer was 0.76.

[Example 3]
The same as in Example 1 except that the Poly (CACzE-MMA) obtained in Production Example 1 and CACzE were mixed so that the component derived from MMA: the component derived from CAZE = 70:30. A rewritable hologram recording material 3 was prepared, and the film thickness thereof was measured. Further, using the rewritable hologram recording material 3, the diffraction efficiency was measured by the same method as in Example 1. The relationship between the time after the start of light irradiation and the diffraction efficiency and memory characteristics is shown in FIGS. 1 and 2.

The film thickness of the rewritable hologram recording material 3 was 80 μm. In the obtained rewritable hologram recording material 3, the total molar concentration of the carbazole azobenzene-derived group contained in the copolymer and the carbazole azobenzene molecule was 1.4 × 10 ^-3 mol / g. It was. The molar ratio of the carbazole azobenzene molecule to the group derived from carbazole azobenzene contained in the copolymer was 1.52.

[Comparative Example 1]
Example 1 and Example 1 except that the Poly (CACzE-MMA) obtained in Production Example 1 was used alone instead of the mixture of Poly (CACzE-MMA) obtained in Production Example 1 and CAZE. A rewritable hologram recording material 4 was prepared in the same manner, and the film thickness thereof was measured. Further, using the rewritable hologram recording material 4, the diffraction efficiency was measured by the same method as in Example 1. The relationship between the time after the start of light irradiation and the diffraction efficiency and memory characteristics is shown in FIGS. 1 and 2.

The film thickness of the rewritable hologram recording material 4 was 82 μm. In the obtained rewritable hologram recording material 4, the molar concentration of the group derived from the carbazole azobenzene contained in the copolymer was 7 × 10 ^-4 mol / g.

[Comparative Example 2]
Same as Example 1 except that Polymethylmethacrylate (PMMA) was used instead of Poly (CACzE-MMA) obtained in Production Example 1 and the PMMA and CACzE were mixed at a weight ratio of 70:30. A rewritable hologram recording material 5 was prepared, and the film thickness thereof was measured. Further, using the rewritable hologram recording material 5, the diffraction efficiency was measured by the same method as in Example 1. The relationship between the time after the start of light irradiation, the diffraction efficiency, and the memory characteristics is shown in FIGS. 1 and 2.

The film thickness of the rewritable hologram recording material 5 was 80 μm. The number of moles of the albazole azobenzene molecule in the obtained rewritable hologram recording material 5 is such that the molar concentration of the group derived from the acrylic molecule constituting the acrylic polymer is 8.8 × 10 ^-4 mol / g. Met.

[result]
From the description of FIG. 1, the rewritable hologram recording material made of the CACzE / (CACzE-MMA) copolymer prepared in Examples 1 to 3 is obtained from the (CACzE-MMA) copolymer alone in the comparative example. It was found that the hologram recording material (Comparative Example 1) and the CAZE dispersed hologram recording material (Comparative Example 2) had higher photoresponsiveness and a shorter rise time in hologram recording.

Further, from the description of FIG. 2, the hologram recording material made of the (CACzE-MMA) copolymer alone (Comparative Example 1) and the CAZE dispersed hologram recording material (Comparative Example 2) have passed a long time since the light irradiation. Then, while the diffraction efficiency is lowered, the rewritable hologram recording material made of the CACzE / (CACzE-MMA) copolymer prepared in Examples 1 to 3 is diffracted even after a long period of time. It was found that the efficiency was hardly attenuated and the memory was better.

[Conclusion]
From the results of Examples 1 to 3 and Comparative Examples 1 and 2 described above, a copolymer in which carbazoleazobenzene was introduced into a part of the side chain of the acrylic polymer, and carbazole introduced in the copolymer. It was found that the rewritable hologram recording material containing a carbazole azobenzene molecule of the same type or different from that of azobenzene has high photoresponsiveness, a shorter rise time in hologram recording, and is more excellent in memory property.

[B: Erasing by circular polarization]
[Example 4]
2 Using a hologram interference hologram recording device, a step of irradiating a hologram recording material 3 which is a recording element with light for hologram recording (object light and reference light) for 50 seconds to record a hologram is performed under the following conditions. After that, the hologram recording material 3 was irradiated with circular polarization for erasing the hologram for 50 seconds to perform a step of erasing the recorded hologram.
-Laser used for recording measurement conditions: 25 mW / 532 nm
Object light, reference light: wavelength 532 nm, intensity 0.535 W / cm ²
Erasing light: wavelength 532 nm, intensity 0.268 W / cm ² .

Subsequently, the step of recording the hologram and the step of erasing the hologram were set, and the set was repeated a total of 5 times including the first set to measure the diffraction efficiency. The relationship between the time from the first light irradiation and the diffraction efficiency obtained as a result is shown in FIG.

[Example 5]
Diffraction efficiency was measured in the same manner as in Example 4 except that the time for irradiating the circularly polarized light for erasing the hologram was extended to 450 seconds and the number of times the above set was repeated was set to 2 times in total. The relationship between the time from the first light irradiation and the diffraction efficiency obtained as a result is shown in FIG.

[Comparative Examples 3 and 4]
Diffraction efficiency was measured in the same manner as in Examples 4 and 5 except that the light for hologram recording and the light for erasing the hologram were linearly polarized light as shown below. The relationship between the time from the first light irradiation and the diffraction efficiency obtained as a result is shown in FIGS. 5 and 6.
-Laser used for recording measurement conditions: 25 mW / 532 nm
Object light, reference light: wavelength 532 nm, intensity 0.535 W / cm ²
Erasing light: wavelength 532 nm, intensity 0.268 W / cm ² .

[result]
From the comparison between FIGS. 3 and 5, when linearly polarized light was used to erase the hologram, the diffraction efficiency gradually decreased when the above recording and erasing sets were repeated, while circularly polarized light was used to erase the hologram. In that case, it was found that the above-mentioned decrease in diffraction efficiency did not occur even when the above-mentioned recording and erasing sets were repeated.

Further, from the comparison between FIGS. 4 and 6, when linearly polarized light is used for erasing the hologram, if the erasing light is irradiated for a long time, the diffraction efficiency when the hologram is recorded again is lowered, while the hologram is erased. It was found that when circularly polarized light was used for erasing, the diffraction efficiency when re-recording the hologram did not decrease even if the erasing light was irradiated for a long time. Therefore, when linearly polarized light is used for erasing the hologram, the recording element may be left for a long time in order to re-record the hologram with the same performance as the first time after irradiating the erasing light for a long time. It is necessary to heat it, but on the other hand, when circularly polarized light is used to erase the hologram, the hologram is re-recorded with the same performance as the first time immediately after irradiating the erasing light for a long time. Turned out to be able to do.

[Conclusion]
From the results of Examples 4 and 5 and Comparative Examples 3 and 4, the copolymer in which carbazoleazobenzene was introduced into a part of the side chain of the acrylic polymer, and the same kind or the same as carbazoleazobenzene introduced in the above copolymer or In a hologram recording / erasing method using a hologram recording element containing a rewritable hologram recording material containing a dissimilar carbazole azobenzene molecule, the time required for erasing the hologram is reduced by using circular polarization for erasing the hologram. It was found that the reduction in response speed and diffraction efficiency in the re-recording after the erasure, which can be shortened and usually decreases, can be prevented.

The hologram recording material and the hologram recording / erasing method of the present invention can suitably improve the rising speed in hologram recording, and can improve the memory property in hologram recording. In addition, re-recording after erasing the hologram can be facilitated. Therefore, it is suitably used for manufacturing a hologram recording device that has a short rise time when recording a hologram, can store the hologram recording for a long period of time, and can appropriately record and erase the hologram repeatedly. can do.

1 Laser oscillator 2 1st fixed mirror 3 1st half-wave plate 4 Beam splitter 5 2nd half-wave plate 6 1st 1/4 wave plate 7 2nd fixed mirror 8 2nd 1/4 wave plate 9 Third fixed mirror 10 Laser oscillator 11 Half-wave plate for probe light 12 Fourth fixed mirror

Claims (14)

A copolymer obtained by introducing carbazoleazobenzene into a part of the side chain of an acrylic polymer, and
A rewritable hologram recording material containing a carbazole azobenzene molecule of the same type or different from that of the above carbazole azobenzene.
(Here, carbazole azobenzene is represented by the following formula (1), and in the formula (1), X is a nitro group, a cyano group, a methoxy group, an amino group or a hydroxy group. )

The rewritable hologram recording material according to claim 1, wherein the carbazole azobenzene is carbazole azobenzene in which X in the above formula (1) is a cyano group, a nitro group or a methoxy group. The rewritable hologram recording material according to claim 1 or 2, wherein the carbazole azobenzene introduced into the side chain of the copolymer and the carbazole azobenzene molecule are of the same type. The rewritable hologram recording material according to any one of claims 1 to 3, wherein the acrylic polymer is selected at least from the group consisting of polymethyl methacrylate, polyethyl methacrylate and polymethyl acrylate. The total molar concentration of the carbazole azobenzene-derived group and the carbazole azobenzene molecule contained in the copolymer with respect to the total weight of the copolymer and the carbazole azobenzene molecule contained in the rewritable hologram recording material. The rewritable hologram recording material according to any one of claims 1 to 4, wherein the amount is 5 × 10 ^-4 mol / g or more and 2.0 × 10 ^{-3 mol / g or less.} The rewriting according to any one of claims 1 to 5, wherein the molar ratio of the carbazole azobenzene molecule to the group derived from carbazole azobenzene contained in the copolymer is 0.5 or more and 2.0 or less. Type hologram recording material. The rewritable hologram recording material according to any one of claims 1 to 6, wherein the copolymer has a weight average molecular weight of 10,000 or more and 200,000 or less. A recording medium having a hologram recording element.
A recording medium, wherein the hologram recording element contains the rewritable hologram recording material according to any one of claims 1 to 7. In a hologram recording element containing a rewritable hologram recording material, a striped pattern on a spatial light modulator (SLM) is interfered with a single light beam of laser light or with interfering object light and reference light. A step of forming interference fringes in the hologram recording element and recording the hologram on the hologram recording element and a step of erasing the hologram by irradiating the hologram recording element with polarized light. It is a method of recording / erasing holograms including
The rewritable hologram recording material is a copolymer obtained by introducing carbazoleazobenzene into a part of the side chain of an acrylic polymer, and
For a hologram recording device made of a material further containing a carbazole azobenzene molecule of the same type or a different type as the carbazole azobenzene introduced into the copolymer.
A hologram recording / erasing method, characterized in that at least the step of erasing the hologram is performed by irradiation with circularly polarized light. The method for recording / erasing a hologram according to claim 9, wherein the object light and the reference light in the recording step are circularly polarized light. The hologram recording / erasing according to claim 9 or 10, further comprising a step of reproducing the recorded hologram by irradiating the hologram recording element on which the hologram is recorded with polarized light having the same phase as the reference light. Method. The method for recording / erasing a hologram according to claim 11, wherein in the step of reproducing the recorded hologram, the polarized light applied to the hologram recording element on which the hologram is recorded is circularly polarized light. A hologram recording device for using the hologram recording / erasing method by two luminous flux interference in order to perform the hologram recording / erasing method according to any one of claims 9 to 12.
A hologram recording apparatus comprising a mechanism for obtaining circular polarization with respect to the hologram recording element through at least the erasing step. The hologram recording device according to claim 13, wherein the mechanism for obtaining the circular polarization is a λ / 4 plate.

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