JP4997135B2 - Holographic recording medium - Google Patents

Description

  The present invention relates to an optical recording composition containing a specific phosphorus compound. More specifically, the present invention relates to an optical recording composition suitable for producing, for example, a holographic recording medium capable of writing information with a 405 nm laser, particularly a volume holographic recording medium having a relatively thick recording layer. Furthermore, the present invention relates to a holographic recording medium having a recording layer formed using the optical recording composition.

  Conventionally, development of a holographic optical recording medium using a holographic principle has been advanced. Information is recorded on a holographic optical recording medium by superimposing information light containing image information and reference light in a recording layer made of a photosensitive composition, and writing interference fringes formed at that time on the recording layer. Done. On the other hand, when information is reproduced, reference light is incident on the recording layer on which information is recorded at a predetermined angle, whereby light diffraction of the reference light due to the formed interference fringes occurs and information light is reproduced.

  In recent years, volume holography, particularly digital volume holography, has been developed in practical use for ultra-high density optical recording and has attracted attention. Volume holography is a method of writing interference fringes in three dimensions by actively utilizing the thickness direction of the optical recording medium. Increasing the thickness increases the diffraction efficiency and increases the recording capacity by using multiple recording. There is a feature that can be achieved. Digital volume holography is a computer-oriented holographic recording method that uses a recording medium and a recording method similar to those of volume holography, but restricts image information to be recorded to a binarized digital pattern. In this digital volume holography, for example, image information such as an analog picture is once digitized, developed into two-dimensional digital pattern information, and recorded as image information. At the time of reproduction, the digital pattern information is read and decoded so that the original image information is restored and displayed. As a result, even if the S / N ratio (signal-to-noise ratio) is somewhat poor during reproduction, the original information can be reproduced with high fidelity by performing differential detection or performing error correction by encoding binary data. Can be reproduced (see Patent Document 1).

Photopolymer holographic optical recording media usually have a recording layer formed from a composition containing a polymerizable monomer and a photopolymerization initiator. For example, Patent Document 2 discloses a 405 nm laser writing technique using an acyl phosphine oxide and a bisacyl phosphine oxide compound as a photopolymerization initiator. Moreover, the said photoinitiator is also available as a commercial item (specifically Darocur TPO (made by Ciba Specialty Chemicals), Irg-819 (made by Ciba Specialty Chemicals)).
Japanese Patent Laid-Open No. 11-311936 US Pat. No. 6,780,546

  In a photopolymer holographic recording medium, in general, by irradiating information light and interference light, polymerization of a recording monomer proceeds, thereby forming an interference image on a recording layer. Then, the interference image is fixed by irradiating the recording layer on which the interference image is formed with fixing light. If a large amount of recording monomer remains at the end point of formation and fixing (recording reaction) of the interference image, the polymerization reaction proceeds further when the recording medium on which the interference image is formed is exposed to bright light, and is stored over time. There is concern that the data will be disturbed. Therefore, in order to improve the record retention, it is desirable that the residual amount of the recording monomer is small at the end of the recording reaction, and such a system design has been desired. However, since the photopolymerization initiator described in Patent Document 2 has a high absorbance, the transmittance in the depth direction decreases as the amount increases, and as a result, the recording sensitivity decreases. However, in the volume holography such as the digital volume holography described above, improvement in sensitivity is required. Therefore, in the photopolymerization initiator described in Patent Document 2, the amount of the photopolymerization initiator that can be added is limited in order to obtain good recording sensitivity in volume holography. For this reason, if the amount of the photopolymerization initiator added is insufficient, the polymerization reaction may not proceed well, and the monomer may remain after the recording reaction.

  Accordingly, an object of the present invention is to use an optical recording composition suitable for digital volume holography, which has excellent recording sensitivity, has a small amount of residual recording monomer at the end of the reaction, and has good recording retention, and the above composition. It is an object of the present invention to provide a holographic recording medium capable of ultra-high density optical recording.

  The present inventor has intensively studied to achieve the above object. As a result, the inventors have found that the above object can be achieved by an optical recording composition containing a specific phosphorus compound represented by the following general formula (I), and have completed the present invention.

That is, the above object was achieved by the following means.
[1] A holographic recording medium having a recording layer formed from an optical recording composition containing a compound represented by the following general formula (I).
[In general formula (I), R ¹ represents a phenyl group having an alkoxy group or a halogen group at the 2-position and the 6-position, and R ² and R ³ each independently represents an alkyl group, an aryl group or a heterocyclic group. , X represents an oxygen atom or a sulfur atom. ]
[2] The holographic recording medium according to [1], wherein in general formula (I), X represents an oxygen atom.
[3] The holographic recording medium according to [1] or [2], wherein R ² and / or R ³ represents an alkyl group in the general formula (I).
[4] The holographic recording medium according to [3], wherein R ² and R ³ represent an alkyl group in the general formula (I).
[5] The holographic recording medium according to any one of [1] to [4], wherein the optical recording composition further contains a radical polymerizable compound.
[6] The holographic recording medium according to any one of [1] to [5], wherein the optical recording composition further contains a thermosetting compound.
[7] The holographic recording medium according to [6], wherein the thermosetting compound includes a polyfunctional isocyanate and a polyfunctional alcohol.

  The phosphorus compound represented by the general formula (I) can maintain good recording sensitivity even if the recording layer contains a sufficient amount for allowing the polymerization reaction to proceed sufficiently. Thereby, it is possible to provide a holographic recording medium in which the remaining amount of unreacted monomer after the recording reaction is small, the recording retention is good, and high sensitivity recording is possible. The holographic recording medium of the present invention is suitable as a recording medium for digital volume holography, which can perform ultra-high density recording and can achieve volume holography, in particular, use of an inexpensive laser and shortening of writing time.

[Optical recording composition]
The optical recording composition of the present invention contains at least a phosphorus compound represented by the following general formula (I), and is used for producing a recording material used in various recording methods for recording information by light irradiation. And is preferably used as a composition for holographic recording, and particularly suitable as a composition for volume holographic recording. As described above, holographic recording is information recording in which information light containing information and reference light are superimposed in a recording layer and information is recorded by writing an interference image formed at that time in the recording layer. Volume holographic recording is an information recording method in which an interference image is three-dimensionally written on a recording layer in holographic recording.
Below, each component contained in the composition for optical recording of this invention is demonstrated.

Phosphorus compounds represented by general formula (I)

In general formula (I), R ¹ , R ² and R ³ each independently represents an alkyl group, an aryl group or a heterocyclic group.
The alkyl group represented by R ¹ , R ² , or R ³ may be linear or branched, and may be unsubstituted or have a substituent. The carbon number is preferably 1-30, and more preferably 1-20. In the present invention, the “carbon number” for a certain group means the carbon number of the portion not containing the substituent for the group having a substituent.

  Examples of the alkyl group include a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, an isobutyl group, a tertiary butyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a heptyl group, and an octyl group. , Tertiary octyl group, 2-ethylhexyl group, decyl group, dodecyl group, octadecyl group, 2,3-dibromopropyl group, adamantyl group, benzyl group, 4-bromobenzyl group and the like. These may further have a substituent. Among these, a tertiary butyl group is most preferable from the viewpoint of stability to nucleophilic compounds such as water and alcohol.

In general formula (I), the aryl group represented by R ¹ , R ² , or R ³ may be unsubstituted or may have a substituent. The carbon number is preferably 6 to 30, and particularly preferably 6 to 20. Specific examples of the aryl group include a phenyl group, a naphthyl group, and an anthranyl group. These may further have a substituent. In particular, R ¹ is preferably an aryl group having an alkyl group, an aryl group, an alkoxy group or a halogen group at at least one of the 2-position and the 6-position, and further an alkyl group or aryl at both the 2-position and the 6-position An aryl group having a group, an alkoxy group or a halogen group is more preferable. For example, R ¹ is preferably 2-methylphenyl group, 2,4,6-trimethylphenyl group, 2,6-dichlorophenyl group, 2,6-dimethoxyphenyl group, 2,6-trifluoromethylphenyl group, Particularly preferred are 2,4,6-trimethylphenyl group, 2,6-dichlorophenyl group, and 2,6-dimethoxyphenyl group. The reason why it is preferable to have the above substituent at one or both of the 2-position and the 6-position is, for example, Jacobi, M .; Henne, A .; Polymers Paint Color Journal 1985, 175, 636. As described in the above, the stability to nucleophilic compounds such as water and alcohol is improved.

  The details of the alkyl group and aryl group as the substituent are the same as described above.

  The alkoxy group as the substituent may be linear or branched, and may be unsubstituted or have a substituent. The number of carbon atoms is preferably 1 to 30, and more preferably 1 to 20. Examples of such alkoxy groups include methoxy, ethoxy, normal propyloxy, isopropyloxy, normal butyloxy, isobutyloxy, tertiary butyloxy, pentyloxy, cyclopentyloxy, hexyloxy. Group, cyclohexyloxy group, heptyloxy group, octyloxy group, tertiary octyloxy group, 2-ethylhexyloxy group, decyloxy group, dodecyloxy group, octadecyloxy group, 2,3-dibromopropyloxy group, adamantyloxy group, Examples thereof include a benzyloxy group and a 4-bromobenzyloxy group, and a methyl group is more preferable.

  Examples of the halogen group as the substituent include a chloro group, a bromo group, and an iodo group, and a bromo group is more preferable.

In general formula (I), the heterocyclic group represented by R ¹ , R ² , or R ³ preferably has 4 to 8 ring members, more preferably 4 to 6 ring members, and particularly preferably 5 or 6 ring members. Specific examples include a pyridine ring, a piperazine ring, a thiophene ring, a pyrrole ring, an imidazole ring, an oxazole ring, and a thiazole ring. These may further have a substituent. Of the heterocycles, a pyridine ring is particularly preferred.

In the general formula (I), when the group represented by R ¹ , R ² , R ³ further has a substituent,
Substituents include halogen groups, alkyl groups, alkenyl groups, alkoxy groups, aryloxy, alkylthio groups, alkoxycarbonyl groups, aryloxycarbonyl groups, amino groups, acyl groups, alkylaminocarbonyl groups, arylaminocarbonyl groups, sulfonamide groups. , Cyano group, carboxy group, hydroxyl group, sulfonic acid group and the like. Among these, a halogen group, an alkoxy group, and an alkylthio group are particularly preferable. Furthermore, as described above, when R ¹ is an aryl group, the aryl group preferably has the above substituents at the 2-position and / or the 6-position.

  In general formula (I), X represents an oxygen atom or a sulfur atom, and is preferably an oxygen atom.

As a preferred embodiment of the compound represented by the general formula (I), X is an oxygen atom or a sulfur atom, and R ¹ has an alkyl group, an aryl group, an alkoxy group or a halogen group at the 2-position and / or the 6-position. Examples thereof include an aryl group, R ² is an alkyl group, and R ³ is an alkyl group. In a more preferred embodiment, X is an oxygen atom, R ¹ is an aryl group having an alkyl group, an aryl group, an alkoxy group or a halogen group at the 2nd and 6th positions, R ² is an alkyl group, and R ³ A compound in which is an alkyl group. In a more preferred embodiment, X is an oxygen atom, R ¹ is a 2,6-dimethoxybenzoyl group or a 2,6-dichlorobenzoyl group, R ² is a butyl group or an isopropyl group, and R ³ is a butyl group. Or the compound which is an isopropyl group can be mentioned.

  Specific examples of the phosphorus compound represented by the general formula (I) are shown below. However, the present invention is not limited to the following specific examples.

  The method for synthesizing the compound represented by the general formula (I) described above is described in detail in DE2830927A1, for example. Moreover, the Example mentioned later can also be referred about a synthesis method.

  The optical recording composition of the present invention contains at least a phosphorus compound represented by the general formula (I). The phosphorus compound represented by the general formula (I) may be used alone or in combination of two or more. There is no restriction | limiting in particular in content of the phosphorus compound represented by general formula (I) in the optical recording composition of this invention, Although it can select suitably according to the objective, 0.01-20 mass% is Preferably, 1-10 mass% is more preferable. When the content is 0.01% by mass or more, an interference image can be secured with high sensitivity. When the content is 30% by mass or less, a recording layer having a sufficient transmittance for recording light and showing good recording sensitivity can be formed. Since the phosphorus compound represented by the general formula (I) has little absorption particularly at a wavelength of 405 nm, when a recording medium having the same OD is produced, a commercially available short wave initiator (for example, trade name Irg-819, Darocure TPO (Ciba Specialty Chemicals), brand name Lucillin TPO (BASF Japan)) can be used in an increased amount.

  In the optical recording composition of the present invention, the phosphorus compound can function as a photopolymerization initiator, preferably a photoradical polymerization initiator. As the photopolymerization initiator, other photopolymerization initiators can be used in combination with the phosphorus compound. The photopolymerization initiator used in combination is not particularly limited as long as it has sensitivity to the recording light, but a photoradical polymerization initiator is preferable in view of the efficiency of the polymerization reaction. When the phosphorus compound and another photopolymerization initiator are used in combination, the content of the photopolymerization initiator used in combination in the optical recording composition is preferably 50% by mass or less, more preferably 30% by mass or less, and more preferably 10%. The mass or less is most preferable.

  Examples of photo radical polymerization initiators that can be used in combination include 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,1′-biimidazole, 2,4, 6-tris (trichloromethyl) -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (p-methoxyphenylvinyl) -1,3,5-triazine, diphenyliodonium tetrafluoroborate, Diphenyliodonium hexafluorophosphate, 4,4′-di-t-butyldiphenyliodonium tetrafluoroborate, 4-diethylaminophenylbenzenediazonium hexafluorophosphate, benzoin, 2-hydroxy-2-methyl-1-phenylpropan-2-one , Benzophenone, thioxanthone, 2,4,6-tri Tylbenzoyldiphenylacylphosphine oxide, triphenylbutylborate tetraethylammonium, bis (η5-2,4-cyclopentadien-1-yl) bis [2,6-difluoro-3- (1H-pyrrol-1-yl) phenyltitanium ] Etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together. Moreover, you may use together the sensitizing dye mentioned later according to the wavelength of the light to irradiate.

Polymerizable Compound The optical recording composition of the present invention can contain a polymerizable compound as a recording compound. As the polymerizable compound, a radical polymerizable compound is preferable from the viewpoint that the polymerization reaction proceeds favorably when used in combination with the compound represented by the general formula (1). Examples of the radical polymerizable compound include radical polymerization monomers having an unsaturated bond such as an acryl group, a methacryl group, a styryl group, and a vinyl group. These polymerizable compounds may be monofunctional or polyfunctional. They may be used alone or in combination with two or more other polymerizable compounds.

  Examples of the radical polymerization type monomer include acryloylmorpholine, phenoxyethyl acrylate, isobornyl acrylate, 2-hydroxypropyl acrylate, 2-ethylhexyl acrylate, 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, neo Pentyl glycol PO modified diacrylate, 1,9-nonanediol diacrylate, hydroxypivalate neopentyl glycol diacrylate, EO modified bisphenol A diacrylate, polyethylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol hexa Acrylate, EO-modified glycerol triacrylate, trimethylol group Pantriacrylate, EO-modified trimethylolpropane triacrylate, 2-naphth-1-oxyethyl acrylate, 2-carbazoyl-9-ylethyl acrylate, (trimethylsilyloxy) dimethylsilylpropyl acrylate, vinyl-1-naphthoate, 2,4 , 6-tribromophenyl acrylate, pentabromo acrylate, phenylthioethyl acrylate, tetrahydrofurfuryl acrylate, bisphenoxyethanol fluorene acrylate, styrene, p-chlorostyrene, N-vinyl carbazole, N-vinyl pyropydone and the like. Among these, phenoxyethyl acrylate, 2,4,6-tribromophenyl acrylate, pentabromoacrylate, and bisphenoxyethanol full orange acrylate are preferable, and 2,4,6-tribromophenyl acrylate and bisphenoxyethanol full orange acrylate are more preferable.

  There is no restriction | limiting in particular in content of the polymeric compound in the composition for optical recording of this invention, Although it can select suitably according to the objective, 1-50 mass% is preferable, and 1-30 mass% is more. Preferably, 3 to 10% by mass is more preferable. If the content is 50% by mass or less, a stable interference image can be easily obtained, and if it is 1% by mass or more, desirable performance can be obtained in terms of diffraction efficiency.

The recording layer of the matrix optical recording medium contains a monomer generally called a matrix, which is related to recording and storage, and a polymer for holding a photopolymerization initiator. The matrix is used for the purpose of enhancing the effects of improving coating properties, film strength, and hologram recording characteristics. The optical recording composition of the present invention can contain a curable compound as a matrix binder and / or a matrix-forming component (matrix precursor). A method of forming a matrix by applying a composition containing a matrix precursor to, for example, a substrate surface and then performing a curing treatment is preferable because a recording layer can be formed without using a solvent or using a small amount of solvent. . As the curable compound, a photocurable compound that is cured by light irradiation using a thermosetting compound or a catalyst can be used, and a thermosetting compound is preferable in terms of recording characteristics.

There is no restriction | limiting in particular as a thermosetting compound contained in the composition for optical recording of this invention. The thermosetting matrix contained in the recording layer can be appropriately selected depending on the purpose. For example, an epoxy compound, a melamine compound, or formalin formed from a urethane resin or oxirane compound formed from an isocyanate compound and an alcohol compound. Examples thereof include polymers and polymers obtained by polymerizing ester compounds and amide compounds of unsaturated acids such as (meth) acrylic acid and itaconic acid.
Among them, a polyurethane matrix formed from an isocyanate compound and an alcohol compound is preferable, and a three-dimensional polyurethane matrix formed from a polyfunctional isocyanate and a polyfunctional alcohol is most preferable from the viewpoint of record retention.
The polyfunctional isocyanate and polyfunctional alcohol that can form the polyurethane matrix will be described in more detail below.

  Specific examples of the polyfunctional isocyanate include biscyclohexylmethane diisocyanate, hexamethylene diisocyanate, phenylene-1,3-diisocyanate, phenylene-1,4-diisocyanate, 1-methoxyphenylene-2,4-diisocyanate, and 1-methyl. Phenylene-2,4-diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, biphenylene-4,4′-diisocyanate, 3 , 3'-dimethoxybiphenylene-4,4'-diisocyanate, 3,3'-dimethylbiphenylene-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate Anate, 3,3′-dimethoxydiphenylmethane-4,4′-diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, naphthylene-1,5-diisocyanate, cyclobutylene-1,3-diisocyanate, cyclo Pentylene-1,3-diisocyanate, cyclohexylene-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate, 1-methylcyclohexylene-2,4-diisocyanate, 1-methylcyclohexylene-2,6-diisocyanate 1-isocyanate-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, cyclohexane-1,3-bis (methylisocyanate), cyclohexane-1,4-bis (methylisocyanate), isophorone diisocyanate , Dicyclohexylmethane-2,4′-diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, ethylene diisocyanate, tetramethylene-1,4-diisocyanate, hexamethylene-1,6-diisocyanate, dodecamethylene-1,12- Diisocyanate, phenyl-1,3,5-triisocyanate, diphenylmethane-2,4,4'-triisocyanate, diphenylmethane-2,5,4'-triisocyanate, triphenylmethane-2,4 ', 4 "-triisocyanate Isocyanate, triphenylmethane-4,4 ', 4 "-triisocyanate, diphenylmethane-2,4,2', 4'-tetraisocyanate, diphenylmethane-2,5,2 ', 5'-tetraisocyanate, cyclohexane-1 , 3,5-Triisocy Nate, cyclohexane-1,3,5-tris (methyl isocyanate), 3,5-dimethylcyclohexane-1,3,5-tris (methyl isocyanate), 1,3,5-trimethylcyclohexane-1,3,5- Stoichiometric excess of tris (methyl isocyanate), dicyclohexylmethane-2,4,2′-triisocyanate, dicyclohexylmethane-2,4,4′-triisocyanine lysine diisocyanate methyl ester, or these organic isocyanate compounds And a bifunctional isocyanate prepolymer obtained by reaction with a polyfunctional active hydrogen-containing compound. Among these, biscyclohexylmethane diisocyanate and hexamethylene diisocyanate are particularly preferable. These may be used individually by 1 type and may use 2 or more types together.

  The polyfunctional alcohol may be a polyfunctional alcohol alone or in a mixed state with other polyfunctional alcohols. Polyfunctional alcohols include glycols such as ethylene glycol, triethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, and neopentyl glycol; diols such as butanediol, pentanediol, hexanediol, heptanediol, and tetramethylene glycol Such as bisphenols, compounds obtained by modifying these polyfunctional alcohols with polyethyleneoxy chain or polypropyleneoxy chain, triols such as glycerin, trimethylolpropane, butanetriol, pentanetriol, hexanetriol, decanetriol, etc. Examples include compounds obtained by modifying functional alcohols with polyethyleneoxy chains or polypropyleneoxy chains.

  The content of the matrix-forming component (or matrix) in the optical recording composition of the present invention is preferably 10 to 95% by mass, and more preferably 35 to 90% by mass. If the content is 10% by mass or more, a stable interference image can be easily obtained, and if it is 95% by mass or less, desirable performance can be obtained in terms of diffraction efficiency.

Other Components A polymerization inhibitor and an antioxidant may be added to the optical recording composition of the present invention as needed for the purpose of improving the storage stability of the optical recording composition.
Examples of the polymerization inhibitor or antioxidant include hydroquinone, p-benzoquinone, hydroquinone monomethyl ether, 2,6-ditertiary butyl-p-cresol, 2,2′-methylenebis (4-methyl-6-tertiary- Butylphenol), trifel phosphite, trisnonylphenyl phosphite, phenothiazine, N-isopropyl-N'-phenyl-p-phenylenediamine and the like.
The addition amount of the polymerization inhibitor or antioxidant is preferably 3% by mass or less based on the total amount of the recording monomer. When the addition amount exceeds 3% by mass, the polymerization may be slowed or may not be polymerized when it is remarkable.

A sensitizing dye can be added to the optical recording composition of the present invention as necessary. Examples of the sensitizing dye include “Research Disclosure, Vol. 200, December 1980, Item 20036” and “sensitizer” (p.160 to p.163, Kodansha; Katsumi Tokumaru and Nobu Okawara, edited by 1987. ) And the like can be used.
Specific examples of the sensitizing dye include a 3-ketocoumarin compound described in JP-A-58-15603, a thiopyrylium salt described in JP-A-58-40302, and JP-B-59-28328. The naphthothiazole merocyanine compound described in JP-A-60-53300, the merocyanine compound described in JP-B-61-9621, JP-A-62-2842, JP-A-59-89303, and JP-A-60-60104 Can be mentioned.
Further, the dyes described in “Functional dye chemistry” (1981, CMC Publishing Co., p.393 to p.416), “Coloring materials” (60 [4] 212-224 (1987)), and the like are also included. be able to. Specific examples include a cationic methine dye, a cationic carbonium dye, a cationic quinoneimine dye, a cationic indoline dye, and a cationic styryl dye.
In addition, coumarin (including ketocoumarin or sulfonocoumarin) dyes, melostyryl dyes, oxonol dyes, hemioxonol dyes, etc .; non-ketopolymethine dyes, triarylmethane dyes, xanthene dyes, anthracene dyes, rhodamine dyes, acridine dyes Non-keto dyes such as aniline dyes and azo dyes; Non-ketopolymethine dyes such as azomethine dyes, cyanine dyes, carbocyanine dyes, dicarbocyanine dyes, tricarbocyanine dyes, hemicyanine dyes, styryl dyes; azine dyes, oxazine dyes, thiazines Dyestuffs, quinoline dyes, quinoneimine dyes such as thiazole dyes, and the like are also included in the spectral sensitizing dyes.
The said sensitizing dye may be used individually by 1 type, and may be used in combination of 2 or more type.

The optical recording composition of the present invention may contain a photothermal conversion material for the purpose of improving the sensitivity of the recording layer formed from the optical recording composition.
The photothermal conversion material is not particularly limited and can be appropriately selected depending on the intended function and performance. For example, it can be easily added to the recording layer together with a photopolymer, or can cause scattering of incident light. Organic dyes are preferred from the standpoint of the absence of properties, and infrared absorbing dyes are preferred in that they do not absorb or scatter light from the light source used for recording.
The infrared absorbing dye is not particularly limited and may be appropriately selected depending on the intended purpose. Cationic dyes, complex salt-forming dyes, quinone neutral dyes, and the like are preferable. The maximum absorption wavelength of the infrared absorbing dye is preferably in the range of 600 to 1,000 nm, and more preferably in the range of 700 to 900 nm.
The content of the infrared absorbing dye can be determined by the absorbance of the wavelength having the highest absorbance in the infrared region in the recording layer formed from the optical recording composition of the present invention. As this light absorbency, the range of 0.1-2.5 is preferable, and the range of 0.2-2.0 is more preferable.

  In the optical recording composition of the present invention, if necessary, a component that diffuses in the direction opposite to the polymerization component may be added to relieve the volume change during polymerization, or an acid cleavage structure may be added. You may add separately the compound which has it in addition to a polymer.

  The optical recording composition of the present invention can be used for various holographic recording compositions capable of recording information by irradiation with light containing information, and is particularly suitable as a volume holographic recording composition. It is. A recording layer can be formed by applying the optical recording composition of the present invention onto a substrate, for example. When the optical recording composition of the present invention contains a thermosetting compound as described above, the matrix can be formed by allowing the curing reaction to proceed by applying the composition under heating after coating. What is necessary is just to determine a heating condition according to the thermosetting compound to be used. If the optical recording composition has a sufficiently low viscosity, the recording layer can be formed by casting. On the other hand, if the viscosity is too high to be cast, a recording layer is placed on the lower substrate using a dispenser, and the upper substrate is pressed onto the recording layer so as to cover it, and the recording layer is spread over the entire surface to form a recording medium. be able to.

[Holographic recording media]
The holographic recording medium of the present invention has a recording layer formed from the optical recording composition of the present invention. For example, a recording layer comprising the holographic recording composition of the present invention can be formed by the method described above.

  The holographic recording medium of the present invention contains a compound represented by the general formula (I) in the recording layer. Thereby, the recording sensitivity can be increased and the amount of the unreacted polymerizable compound (residual monomer) after the recording reaction can be reduced.

  The holographic recording medium of the present invention includes the recording layer (holographic recording layer), and preferably includes a lower substrate, a filter layer, a holographic recording layer, and an upper substrate. And other layers such as a reflective film, a filter layer, a first gap layer, and a second gap layer.

  The holographic recording medium of the present invention is capable of recording / reproducing information using the principle of hologram, and is a volume for recording a large amount of information such as a relatively thin planar hologram or a three-dimensional image for recording information such as two dimensions. It may be a hologram, and may be either a transmission type or a reflection type. The holographic recording medium of the present invention is suitable as a volume holographic recording medium for which high recording density is required because high capacity information recording is possible.

  Further, the recording method of the hologram on the holographic recording medium of the present invention is not particularly limited, and for example, an amplitude hologram, a phase hologram, a blazed hologram, a complex amplitude hologram, or the like may be used. Among these, information recording in the volume holographic recording area is performed by irradiating the volume holographic recording area with information light and reference light as a coaxial light beam, and recording information by an interference pattern due to interference between the information light and the reference light. The so-called collinear method is particularly preferable.

  Below, the detail of the board | substrate and each layer which may be contained in the holographic recording medium of this invention is demonstrated one by one.

-Board-
There is no restriction | limiting in particular about the shape, a structure, a magnitude | size, etc. of a board | substrate, According to the objective, it can select suitably. Examples of the shape include a disk shape and a card shape, and a material that can ensure the mechanical strength of the holographic recording medium should be selected. In addition, when light used for recording and reproduction enters through the substrate, it is preferable that the light is sufficiently transparent in the wavelength region of the light used.

  As the substrate material, glass, ceramics, resin, and the like are usually used, and resin is particularly preferable from the viewpoint of moldability and cost. Examples of the resin include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer, polyethylene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, urethane resin, and the like. Among these, polycarbonate resin and acrylic resin are particularly preferable from the viewpoints of moldability, optical characteristics, and cost. As a board | substrate, what was synthesize | combined suitably may be used and a commercial item may be used.

  The substrate is usually provided with a plurality of address-servo areas as linearly extending positioning areas at predetermined angular intervals, and a sector-shaped section between adjacent address-servo areas is a data area. . In the address-servo area, information for performing focus servo and tracking servo by the sampled servo method and address information are recorded in advance by embossed pits (servo pits) or the like (preformat). Note that the focus servo can be performed using the reflective surface of the reflective film. As information for performing the tracking servo, for example, a wobble pit can be used. In the case where the holographic recording medium has a card shape, the servo pit pattern may be omitted.

  There is no restriction | limiting in particular as thickness of a board | substrate, According to the objective, it can select suitably, 0.1-5 mm is preferable and 0.3-2 mm is more preferable. If the thickness of the substrate is 0.1 mm or more, the distortion of the shape during storage of the disc can be suppressed, and if it is 5 mm or less, the mass of the entire disc increases and an excessive load is applied to the drive motor. It can be avoided.

-Recording layer-
The recording layer is formed from the optical recording composition of the present invention, and information can be recorded using holography. There is no restriction | limiting in particular as thickness of a recording layer, According to the objective, it can select suitably. If the thickness of the recording layer is in the range of 1 to 1,000 μm, a sufficient S / N ratio can be obtained even if shift multiplexing of 10 to 300 is performed, and if it is in the range of 100 to 700 μm, this is remarkable. This is advantageous.

-Reflective film-
The reflective film can be formed on the servo pit pattern surface of the substrate.
As a material for the reflective film, a material having a high reflectance with respect to information light and reference light is preferably used. When the wavelength of light used as information light and reference light is 400 to 780 nm, for example, it is preferable to use Al, Al alloy, Ag, Ag alloy, or the like. When the wavelength of light used as information light and reference light is 650 nm or more, it is preferable to use Al, Al alloy, Ag, Ag alloy, Au, Cu alloy, TiN, or the like.
In addition, by using an optical recording medium that reflects light and can be added or erased as a reflective film, for example, a DVD (digital video disk), it is possible to rewrite to what area the hologram has been recorded. It is also possible to additionally write and rewrite directory information such as in which part an error exists and how the alternation process was performed without affecting the hologram.

The method for forming the reflective film is not particularly limited and can be appropriately selected according to the purpose. Various vapor deposition methods such as vacuum deposition, sputtering, plasma CVD, photo CVD, ion plating An electron beam evaporation method or the like is used. Among these, the sputtering method is excellent in terms of mass productivity and film quality.
The thickness of the reflective film is preferably 50 nm or more, and more preferably 100 nm or more so that sufficient reflectance can be achieved.

-Filter layer-
The filter layer can be provided on the servo pits of the substrate, on the reflective layer, or on the first gap layer described later.
The filter layer has a wavelength selective reflection function that reflects only light of a specific wavelength from among a plurality of types of light rays, transmits the first light, and reflects the second light. In particular, even if the incident angle changes, the selective reflection wavelength does not shift, and the function of preventing irregular reflection from the reflection film of the recording medium by the information light and the reference light and the generation of noise are also provided. By laminating filter layers, optical recording with high resolution and excellent diffraction efficiency can be performed.
There is no restriction | limiting in particular as a filter layer, According to the objective, it can select suitably, For example, a dichroic mirror layer, a coloring material containing layer, a dielectric material vapor deposition layer, a single layer or two or more cholesteric layers, and as needed It is possible to form a laminate in which at least one of the other layers appropriately selected is laminated. Although the thickness is not specifically limited, For example, it is about 0.5-20 micrometers.
The filter layer may be directly laminated on the substrate together with the recording layer or the like, or may be laminated on a substrate such as a film to produce a filter layer, which may be laminated on the substrate.

-First gap layer-
The first gap layer is provided between the filter layer and the reflective film as necessary, and is formed for the purpose of smoothing the lower substrate surface. It is also effective for adjusting the size of the hologram generated in the recording layer. That is, since it is necessary for the recording layer to form an interference area for the recording reference light and the information light to a certain extent, it is effective to provide a gap between the recording layer and the servo pit pattern.

The first gap layer can be formed, for example, by applying a material such as an ultraviolet curable resin on the servo pit pattern by spin coating or the like and curing it. Moreover, when using what apply | coated and formed on the transparent base material as a filter layer, this transparent base material will work | function also as a 1st gap layer.
There is no restriction | limiting in particular as thickness of a 1st gap layer, According to the objective, it can select suitably, 1-200 micrometers is preferable.

-Second gap layer-
The second gap layer is provided between the recording layer and the filter layer as necessary.
There is no restriction | limiting in particular as a material of a 2nd gap layer, According to the objective, it can select suitably, For example, a triacetyl cellulose (TAC), a polycarbonate (PC), a polyethylene terephthalate (PET), a polystyrene (PS) Transparent resin films such as polysulfone (PSF), polyvinyl alcohol (PVA), polymethyl methacrylate = polymethyl methacrylate (PMMA), etc., or JSR brand name ARTON film or Nippon Zeon brand name ZEONOR Examples thereof include norbornene resin films. Among these, those having high isotropic properties are preferred, and TAC, PC, trade name ARTON, and trade name ZEONOR are particularly preferred.
There is no restriction | limiting in particular as thickness of a 2nd gap layer, According to the objective, it can select suitably, 1-200 micrometers is preferable.
Hereinafter, the holographic recording medium of the present invention will be described in more detail based on specific embodiments. However, the present invention is not limited to the following specific embodiments.

<First embodiment>
FIG. 1 is a schematic cross-sectional view showing the configuration of the holographic recording medium according to the first embodiment. In the holographic recording medium 21 according to the first embodiment, a servo pit pattern 3 is formed on a polycarbonate resin substrate or glass substrate 1, and the servo pit pattern 3 is coated with aluminum, gold, platinum, or the like to be a reflective film 2 is provided. In FIG. 1, the servo pit pattern 3 is formed on the entire surface of the lower substrate 1. However, the servo pit pattern may be formed periodically. The height of the servo pit pattern 3 is usually 1750 mm (175 nm), which is sufficiently smaller than the thicknesses of the substrate and other layers.

  The first gap layer 8 is formed by applying a material such as an ultraviolet curable resin on the reflective film 2 of the lower substrate 1 by spin coating or the like. The first gap layer 8 is effective for protecting the reflective film 2 and adjusting the size of the hologram generated in the recording layer 4. That is, providing a gap between the recording layer 4 and the servo pit pattern 3 is effective for forming a recording reference light and information light interference region in the recording layer 4 to a certain size.

  A filter layer 6 is provided on the first gap layer 8, and a holographic recording medium 21 is configured by sandwiching the recording layer 4 between the filter layer 6 and the upper substrate 5 (polycarbonate resin substrate or glass substrate).

In FIG. 1, the filter layer 6 transmits only red light and does not transmit light of other colors. Therefore, since the information light, the recording and reproduction reference light are green or blue light, the light does not pass through the filter layer 6 and does not reach the reflection film 2 but becomes return light and is emitted from the incident / exit surface A. Become.
The filter layer 6 is a multilayer deposited film in which high refractive index layers and low refractive index layers are alternately stacked.
The filter layer 6 made of this multilayer deposited film may be directly formed on the first gap layer 8 by vacuum deposition, or a film in which the multilayer deposited film is formed on the substrate is punched into a holographic recording medium shape. May be.

  The holographic recording medium 21 in the present embodiment may have a disk shape or a card shape. In the case of a card shape, there is no need for the servo pit pattern. In the holographic recording medium 21, the lower substrate 1 is 0.6 mm, the first gap layer 8 is 100 μm, the filter layer 6 is 2 to 3 μm, the recording layer 4 is 0.6 mm, and the upper substrate 5 is 0.6 mm. The total thickness is about 1.9 mm.

Next, an optical system that can be used for recording and reproducing information on the holographic recording medium 21 will be described with reference to FIG.
First, light (red light) emitted from the servo laser is reflected almost 100% by the dichroic mirror 13 and passes through the objective lens 12. The servo light is irradiated onto the holographic recording medium 21 by the objective lens 12 so as to focus on the reflective film 2. That is, the dichroic mirror 13 transmits light having a wavelength of green or blue, and reflects light having a wavelength of red almost 100%. The servo light incident from the light incident / exit surface A of the holographic recording medium 21 passes through the upper substrate 5, the recording layer 4, the filter layer 6, and the first gap layer 8, is reflected by the reflective film 2, and again The first gap layer 8, the filter layer 6, the recording layer 4, and the upper substrate 5 are transmitted through the incident / exit surface A. The returned return light passes through the objective lens 12, is reflected almost 100% by the dichroic mirror 13, and servo information is detected by a servo information detector (not shown). The detected servo information is used for focus servo, tracking servo, slide servo, and the like. If the hologram material constituting the recording layer 4 is not sensitive to red light, even if the servo light passes through the recording layer 4 or the servo light is irregularly reflected by the reflective film 2, Has no effect. Further, since the return light of the servo light reflected by the reflection film 2 is reflected almost 100% by the dichroic mirror 13, the servo light is detected by the CMOS sensor or the CCD 14 for detecting the reproduced image. In addition, there is no noise with respect to the reproduction light.

  The information light and the recording reference light generated from the recording / reproducing laser pass through the polarizing plate 16 to become linearly polarized light, pass through the half mirror 17 and pass through the quarter wavelength plate 15. It becomes circularly polarized light. Through the dichroic mirror 13, the objective lens 12 irradiates the holographic recording medium 21 with information light and recording reference light so as to generate an interference pattern in the recording layer 4. The information light and the recording reference light enter from the incident / exit surface A and interfere with each other in the recording layer 4 to generate an interference pattern there. Thereafter, the information light and the recording reference light pass through the recording layer 4 and enter the filter layer 6, but are reflected to the bottom surface of the filter layer 6 to become return light. That is, the information light and the recording reference light do not reach the reflective film 2. This is because the filter layer 6 is a multilayer deposited layer in which a plurality of high refractive index layers and low refractive index layers are alternately stacked, and has a property of transmitting only red light.

<Second Embodiment>
FIG. 2 is a schematic cross-sectional view showing the configuration of the holographic recording medium according to the second embodiment. In the holographic recording medium 22 according to the second embodiment, a servo pit pattern 3 is formed on a polycarbonate resin or glass substrate 1, and the surface of the servo pit pattern 3 is coated with aluminum, gold, platinum, etc. Is provided. The height of the servo pit pattern 3 is the same as that of the first embodiment in that it is normally 1750 mm (175 nm).

  The difference in structure between the second embodiment and the first embodiment is that the second gap layer 7 is provided between the filter layer 6 and the recording layer 4 in the holographic recording medium 22 according to the second embodiment. It is that. The second gap layer 7 has a point where information light and reproduction light are focused. If this area is filled with a photopolymer, excessive consumption of monomers due to overexposure occurs, resulting in a decrease in multiple recording capability. Therefore, it is effective to provide a non-reactive and transparent second gap layer.

  A filter layer 6, which is a multilayer deposited film in which a plurality of high refractive index layers and low refractive index layers are alternately stacked, is formed on the first gap layer 8 after the first gap layer 8 is formed. The thing similar to embodiment can be used.

  In the holographic recording medium 22 of the second embodiment, the lower substrate 1 is 1.0 mm, the first gap layer 8 is 100 μm, the filter layer 6 is 3 to 5 μm, the second gap layer 7 is 70 μm, and the recording layer 4. Is 0.6 mm, the upper substrate 5 is 0.4 mm thick, and the total thickness is about 2.2 mm.

  Next, when information is recorded or reproduced, red servo light and green information light and recording and reproduction reference light are applied to the holographic recording medium 22 of the second embodiment having the above-described structure. Is irradiated. The servo light enters from the incident / exit surface A, passes through the recording layer 4, the second gap layer 7, the filter layer 6, and the first gap layer 8 and is reflected by the reflective film 2 to become return light. The return light again passes through the first gap layer 8, the filter layer 6, the second gap layer 7, the recording layer 4, and the upper substrate 5 in this order, and is emitted from the incident / exit surface A. The emitted return light is used for focus servo, tracking servo, and the like. If the hologram material constituting the recording layer 4 is not sensitive to red light, even if the servo light passes through the recording layer 4 or the servo light is irregularly reflected by the reflective film 2, Has no effect. Green information light or the like enters from the incident / exit surface A, passes through the recording layer 4 and the second gap layer 7, is reflected by the filter layer 6, and becomes return light. The return light again passes through the second gap layer 7, the recording layer 4 and the upper substrate 5 in this order, and exits from the incident / exit surface A. Also during reproduction, not only the reproduction reference light but also the reproduction light generated by irradiating the reproduction reference light onto the recording layer 4 is emitted from the incident / exit surface A without reaching the reflection film 2. The optical operation in the vicinity of the holographic recording medium 22 (the objective lens 12, the filter layer 6, the CMOS sensor or the CCD 14 as a detector in FIG. 3) is the same as in the first embodiment, and a description thereof will be omitted.

  Information can be recorded on the holographic recording medium of the present invention by irradiating the holographic recording medium of the present invention with light. Preferably, information recording is performed by irradiating the recording layer formed from the optical recording composition of the present invention with information light and reference light to form an interference image on the recording layer. The recording layer can be irradiated with fixing light to fix the interference image. The holographic recording medium of the present invention can reduce the amount of residual monomer and obtain excellent recording retention properties through the above recording operation and fixing operation, and can exhibit higher recording sensitivity.

  As information light, coherent light can be used. An interference image generated by the interference between the information light and the reference light by irradiating the recording medium with the information light and the reference light so that the optical axis of the information light and the optical axis of the reference light are coaxial. Can be recorded on the recording layer. Specifically, the information light provided with a two-dimensional intensity distribution and the information light and a reference light having a substantially constant intensity are superposed inside the recording layer, and recording is performed using an interference pattern formed by them. Information can be recorded by creating a distribution of optical properties within the layer. The wavelengths of the information light and the reference light are preferably 400 nm or more, more preferably 400 to 2000 nm, and particularly preferably 400 to 700 nm.

  After information recording (interference image formation) is performed by irradiation with information light and reference light, fixing light is irradiated to fix the interference image. The wavelength of the interference light is preferably less than 400 nm, more preferably 100 nm or more and less than 400 nm, and particularly preferably 200 nm or more and less than 400 nm.

  Information can be reproduced by irradiating the interference light formed by the above method with reference light. When reading (reproducing) the written information, the recording layer is irradiated with only the reference light in the same arrangement as during recording, and the reproduction light having an intensity distribution corresponding to the optical characteristic distribution formed inside the recording layer is obtained. The light is emitted from the recording layer.

Next, an optical recording / reproducing apparatus suitably used for recording and reproducing information on the holographic recording medium of the present invention will be described with reference to the drawings.
FIG. 4 is a configuration diagram showing a holographic recording apparatus that can be used in the present invention, and FIG. 5 is a diagram for explaining an effective numerical aperture NA. FIG. 6 is a block diagram showing a holographic recording apparatus that can be used for recording and reproducing information on a reflective medium. 7A and 7B are diagrams illustrating patterns of matrix-shaped information light and reference light, where FIG. 7A shows a case where the numerical aperture is large and FIG. 7B shows a case where the numerical aperture is small.

Next, information recording / reproduction will be described with reference to FIGS.
The holographic recording apparatus 10 shown in FIG. 4 mainly includes a light source 31, a mirror 32, a DMD element 33, objective lenses 36a and 36b, a data reading device 37, a pedestal 39, and a control device 40.
The light source 31 is a light source that emits coherent light, and is arranged in a direction to emit the light toward the mirror 32.
The mirror 32 is arranged in a direction that reflects light from the light source 31 toward the DMD element 33.

  The DMD element 33 includes a plurality of minute mirrors 33a arranged in a matrix and a switching device 33b for switching the direction of each mirror 33a, and transmits light emitted from the mirror 32 side to a predetermined level. The information light IB and the reference light RB are generated by being reflected by the mirror 33a. For example, a part of the plurality of mirrors 33a arranged in the ring-shaped region near the outer periphery is directed toward the objective lens 36a in a fixed pattern, and the ring-shaped light reflected by the part of the mirrors 33a is used as the reference light RB. (See FIGS. 7A and 7B). In addition, the orientation of the plurality of mirrors 33a arranged inside some of the mirrors 33a forming the reference light RB is appropriately set to the orientation on the objective lens 36a side and the other orientation based on the data input from the control device 40. The light that is set and reflected by the mirror 33a in the inner region is used as information light IB (see FIGS. 7A and 7B). That is, the DMD element 33 arranges optical information in a matrix on the cross section of the information light IB.

  The objective lens 36 a focuses the reference light RB and the information light IB coming from the DMD element 33 and causes these lights to interfere in the recording layer 82 of the recording medium 80. The objective lens 36a, the pedestal 39, and the recording medium 80 are arranged so that the optical axis of the light focused by the objective lens 36a is perpendicular to the recording layer 82 (perpendicular to the plane direction and along the thickness direction). Is arranged.

  The data reading device 37 reads the light diffracted by the interference fringe and passing through the objective lens 36b as data by irradiating the interference fringe recorded on the recording layer 82 with reading light equivalent to the reference light RB. Specifically, since the light entering the data reading device 37 includes the same matrix optical information as the information light IB at the time of recording, a CMOS, a CCD, or the like is used to read the matrix optical information. Can be used.

  Since the pedestal 39 supports the recording medium 80 and changes the recording position on the recording medium 80, the pedestal 39 can move relative to the light in a direction perpendicular to the optical axis of the light incident on the recording medium 80. As a result, information can be recorded on the entire surface of the recording medium 80. For example, the pedestal 39 can be configured as a rotary stage. Although not shown in detail, the objective lens 36 may be movable relative to the pedestal 39.

The control device 40 is a device that digitally controls the light source 31, the DMD element 33, and the pedestal 39.
The control device 40 is connected to a device that instructs the holographic recording device 1 to record information, such as a personal computer terminal or a recording device. When information is recorded, information is input from these devices, and information is read out. In this case, the read information is output to these devices.
When recording information, the control device 40 changes the direction of the mirror 33a of the DMD element 33 according to the information to be recorded and emits light from the light source 31 to generate the information light IB and the reference light RB. Further, the pedestal 39 is driven to record a recording spot (interference fringe) at an appropriate position on the recording medium 80.
When reading information from the recording medium 80, the control device 40 controls the mirror 33a in the area corresponding to the information light IB of the DMD element 33 so that the light does not go to the objective lens 36a, and the reference light RB. The recording medium 80 is irradiated with only the reference light RB by controlling the mirror 33a in the corresponding area in the same pattern direction as that during recording. Further, the pedestal 39 is driven so that the reference beam RB is irradiated to the recording spot (interference fringe) to be read out of the recording medium 80. The information light IB incident on the data reading device 37 is acquired and output to the device that has instructed reading.

  In this embodiment, the recording medium 80 is a transmissive holographic recording medium 80 having no reflective layer. For example, a reflective holographic recording medium 80 having a reflective layer between the substrate 81 and the recording layer 82 is used. In the case of recording / reproducing information on a graphic recording medium, as shown in FIG. 6, the configuration shown in the holographic recording device 2 in which a deflection beam splitter 34 and a quarter wavelength plate 35 are added to the holographic recording device 1. Can be used for recording and reproduction. Hereinafter, recording / reproduction in the recording apparatus shown in FIG. 6 will be described.

The holographic recording device 11 shown in FIG. 6 mainly includes a light source 31, a mirror 32, a DMD element 33, a splitter 34, a wave plate 35, an objective lens 36, a data reading device 37, a pedestal 39, and a control device 40. ing.
The light source 31 is a light source that emits coherent light, and is arranged in a direction to emit the light toward the mirror 32.
The mirror 32 is arranged in a direction that reflects light from the light source 31 toward the DMD element 33.

  The DMD element 33 includes a plurality of minute mirrors 33a arranged in a matrix and a switching device 33b for switching the direction of each mirror 33a, and transmits light emitted from the mirror 32 side to a predetermined level. The information light IB and the reference light RB are generated by being reflected by the mirror 33a. For example, a part of the plurality of mirrors 33a arranged in the ring-shaped region near the outer periphery is directed toward the splitter 34 in a fixed pattern, and the ring-shaped light reflected by the part of the mirrors 33a is used as the reference light RB ( (Refer FIG. 7 (a), (b)). In addition, the orientations of the plurality of mirrors 33a arranged inside some of the mirrors 33a that form the reference light RB are appropriately set to the orientation on the splitter 34 side and other orientations based on the data input from the control device 40. The light reflected by the mirror 33a in the inner region is used as information light IB (see FIGS. 7A and 7B). That is, the DMD element 33 arranges optical information in a matrix on the cross section of the information light IB.

  The splitter 34 transmits light emitted from the DMD element 33 side to the wave plate 35 side and reflects light emitted from the wave plate 35 side to the data reader 37 side.

  The wave plate 35 is a so-called quarter wave plate, and has a function of converting linear deflection into circular deflection and converting circular deflection into linear deflection.

  The objective lens 36 focuses the reference light RB and the information light IB that have passed through the splitter 34 and the wavelength plate 35 from the DMD element 33 side, and causes these lights to interfere in the recording layer 82 of the recording medium 80. The objective lens 36, the pedestal 39, and the recording medium 80 are arranged so that the optical axis of the light focused by the objective lens 36 is perpendicular to the recording layer 82 (perpendicular to the plane direction and along the thickness direction). Is arranged.

  The data reading device 37 sequentially passes and reflects the objective lens 36, the wavelength plate 35, and the splitter 34 from the interference fringe side by applying the reading light equivalent to the reference light RB to the interference fringes recorded on the recording layer 82. It reads light as data. Specifically, since the light entering the data reading device 37 includes the same matrix optical information as the information light IB at the time of recording, a CMOS, a CCD, or the like is used to read the matrix optical information. Can be used.

Since the pedestal 39 supports the recording medium 80 and changes the recording position on the recording medium 80, the pedestal 39 can move relative to the light in a direction perpendicular to the optical axis of the light incident on the recording medium 80. As a result, information can be recorded on the entire surface of the recording medium 80. For example, the pedestal 39 can be configured as a rotary stage. Although not shown in detail, the objective lens 36 may be movable relative to the pedestal 39.
The control device 40 is a device that digitally controls the light source 31, the DMD element 33, and the pedestal 39.

4 and 6, the control device 40 is connected to a device that instructs the holographic recording devices 10 and 11 to record information, such as a personal computer terminal or a recording device. Information is input from the devices, and when the information is read, the read information is output to these devices.
When recording information, the control device 40 changes the direction of the mirror 33a of the DMD element 33 according to the information to be recorded and emits light from the light source 31 to generate the information light IB and the reference light RB. Further, the pedestal 39 is driven to record a recording spot (interference fringe) at an appropriate position on the recording medium 80.
When reading information from the recording medium 80, the control device 40 controls the mirror 33a in the region corresponding to the information light IB of the DMD element 33 so that the light does not go to the objective lens 36, and the reference light RB. The recording medium 80 is irradiated with only the reference light RB by controlling the mirror 33a in the corresponding area in the same pattern direction as that during recording. Further, the pedestal 39 is driven so that the reference beam RB is irradiated to the recording spot (interference fringe) to be read out of the recording medium 80. The information light IB incident on the data reading device 37 is acquired and output to the device that has instructed reading.

  Although the specific aspect of the holographic recording apparatus that can be used in the present invention has been described above, the present invention is not limited to the above-described aspect, and can be appropriately modified and implemented. For example, it is possible to record more information by recording a plurality of recording spots having different information using a conventionally known shift multiplexing method, code multiplexing method or phase code multiplexing multiplexing method. It is. Further, the configuration of the recording medium 80 is not limited to the illustrated one, and may have other layers such as a servo layer separately.

  Hereinafter, the present invention will be further described based on examples. However, this invention is not limited to the aspect shown in the Example.

<Synthesis Example of Compound Represented by General Formula (I)>
Exemplified compounds I-2, I-3, I-8, and I-9 were synthesized according to the following general scheme in accordance with the method described in DE2830927A1. In the following scheme, R ^{1 to} R ³ have the same definitions as in general formula (I). By changing the synthesis raw material, various compounds having different R ^{1 to} R ³ can be synthesized according to the following scheme.

  As specific examples, synthesis schemes and identification results of Exemplified Compounds I-8 and I-9 are shown below.

<I-8>
¹ H NMR (300 MHz, CDCl ₃ ) δ0.91 (t, 6H), 1.38 (dd, 4H), 1.64 (dd, 4H), 3.82 (s, 6H), 4.08-4.19 (m, 4H), 6.59 (d, 2H), 7.38 (t, 1H)
<I-9>
¹ H NMR (300 MHz, CDCl ₃ ) δ1.32 (d, 6H), 1.39 (d, 6H), 4.82-4.94 (m, 2H), 7.33 (s, 3H)

Example 1
-Preparation of composition for holographic recording-
6.4 g of hexamethylene diisocyanate (Mitsui Chemical Polyurethane Co., Ltd., trade name: Takenate T-700), 5.21 g of polypropylene oxide triol (Mitsui Chemical Polyurethane Co., Ltd., trade name MN-300), polyethylene glycol (Tokyo) (Made by Kasei Kogyo Co., Ltd.) 4.64 g, 9,9′-biphenylfluorene EO-modified acrylate (manufactured by Osaka Gas Chemical Co., Ltd., trade name: Ogsol EA0200), 1.60 g of Exemplified Compound I-8, and A holographic recording composition was prepared by mixing 0.20 g of a cured amine catalyst (manufactured by San Apro Co., Ltd., trade name: U-CAT 410) under a nitrogen stream.

(Example 2)
-Preparation of composition for holographic recording-
In Example 1, a holographic recording composition was prepared in the same manner as in Example 1 except that Exemplified Compound I-3 was used instead of Exemplified Compound I-8.

(Comparative Example 1)
-Preparation of composition for holographic recording-
6.4 g of hexamethylene diisocyanate (Mitsui Chemical Polyurethane Co., Ltd., trade name: Takenate T-700), 5.21 g of polypropylene oxide triol (Mitsui Chemical Polyurethane Co., Ltd., trade name MN-300), polyethylene glycol (Tokyo) (Made by Kasei Kogyo Co., Ltd.) 4.64 g, 9,9′-biphenylfluorene EO-modified acrylate (Osaka Gas Chemical Co., Ltd., trade name: Ogsol EA0200), photopolymerization initiator (2,4,6) -0.16 g of trimethylbenzoylphenylphosphinic acid ethyl ester, trade name Lucillin TPO-L, manufactured by BASF Japan Ltd.) and 0.20 g of cured amine catalyst (trade name: U-CAT 410 manufactured by San Apro Co., Ltd.) in a nitrogen stream Under mixing, a holographic recording composition was prepared.

(Comparative Example 2)
-Preparation of composition for holographic recording-
Vitec WE-180 isocyanate (manufactured by Bayer) 3.85 g, polypropylene oxide triol (manufactured by Mitsui Chemicals Polyurethanes Co., Ltd., product name MN-1000) 5.63 g, 2,4,6-tribromophenyl acrylate 0.35 g, photopolymerization started 0.08 g of an agent (Irg-819 manufactured by Ciba Specialty Chemicals) and 0.09 g of a cured tin catalyst dibutyl dilaurate tin (manufactured by Tokyo Chemical Industry Co., Ltd.) were mixed in a nitrogen stream to prepare a composition for holographic recording.

(Examples 3 and 4, Comparative Examples 3 and 4)
-Production of optical recording media-
An antireflection treatment was performed on one surface of 0.5 mm thick glass so that the reflectance by incident light perpendicular to the wavelength of 405 nm was 0.1%, and a first substrate was produced.
An aluminum vapor deposition process was performed on one surface of a 0.5 mm thick glass so that the reflectance by incident light perpendicular to the wavelength of 405 nm was 90%, thereby producing a second substrate.
Next, a transparent polyethylene terephthalate sheet having a thickness of 500 μm was provided as a spacer on the surface of the first substrate not subjected to the antireflection treatment.
Next, the holographic recording compositions of Examples 1 and 2 and Comparative Examples 1 and 2 were each placed on the first substrate, and the aluminum-deposited surface of the second substrate was aired on the holographic recording composition. The first substrate and the second substrate were bonded to each other through a spacer so as not to be caught. Thereafter, the optical recording media of Examples 3 and 4 and Comparative Examples 3 and 4 were prepared by allowing to stand at 80 ° C. for 6 hours. The thickness of the formed recording layer was 200 μm.

<Recording on optical recording media and evaluation>
(1) Measurement of recording sensitivity by digital tester Using the hologram recording / reproducing tester shown in FIG. 4 described above for each of the optical recording media of Examples 5 to 8 and Comparative Examples 3 and 4, the focus of the recording hologram A hologram was written with a recording spot diameter of 200 μm at the position, and the sample was fixed until the recording light source almost disappeared (fixing light source: KEYENCE UV-LED (UV-300), wavelength 300 nm). Thereafter, sensitivity (recording energy) was evaluated as follows. The wavelength of information light for recording, the wavelength of reference light, and the wavelength of reproduction light were all 405 nm.
-Measurement of sensitivity-
The irradiation light energy (mJ / cm ² ) at the time of recording was changed, and the change in the error probability (BER: Bit Error Rate) of the reproduction signal was measured. Usually, the luminance of the reproduction signal increases with the increase of irradiation light energy, and the BER of the reproduction signal tends to gradually decrease. Here, the lowest irradiation light energy at which a substantially good reproduced image (BER <10 ⁻³ ) can be obtained is defined as the recording sensitivity of the optical recording medium. The results are shown in Table 1.

(2) Measurement of recording capacity by plane wave tester FIG. 8 shows an outline of the optical system of the plane wave recording system. A SONY blue laser “Littrow” (wavelength: 405 nm) was used as the recording light source, and a He—Ne laser (wavelength: 633 nm) having no absorption in the medium was used as the probe light source. The light amount of the recording light source is 4 [mW] for the signal light and the reference light together, the light amount of the probe light source is 5 [mW], the crossing angle between the signal light and the reference light is 43.2 ° (lattice interval: 550 nm), and the probe light The incident angle was 35.1 °, which is an angle satisfying the Bragg condition, and the recording spot diameter was 6 mmφ. The dynamic range of the storage capacity is represented by an index called M #. The recording capacity of each of the optical recording media of Examples 3 and 4 and Comparative Examples 3 and 4 was measured by the optical system. The measurement will be described below.
61 multiplex recording was performed at 1 ° intervals from −30 to + 30 ° so that the diffraction efficiency per time was 1 to 3% as a standard and the sensitivity of the recording material almost disappeared so as not to exceed 10%. The sample is subjected to a fixing process until absorption with respect to the recording light source substantially disappears (fixing light source: high power UV-LED (UV-400) manufactured by KEYENE), and evaluation of angle selectivity from −32 to + 32 ° at intervals of 0.01 °. And M # was calculated by integrating the half power of the diffraction efficiency η _i of the obtained peak. The diffraction efficiency η was evaluated as follows. The results are shown in Table 1.
η = diffracted light / (diffracted light + transmitted light) × 100
M # = Σ√η _i

(3) Measurement of residual monomer amount The entire surface of the optical recording medium produced above was irradiated with light of 20,000 nm at 20000 mJ / cm ² to extract the remaining monomer from the recording medium. The amount of monomer extracted by liquid chromatography using a calibration curve method was quantified. The results are shown in Table 1.

  From the results of Table 1, the optical recording media of Examples 3 and 4 using the holographic recording compositions of Examples 1 and 2 are Comparative Example 3 using the holographic recording compositions of Comparative Examples 1 and 2. It can be seen that all have excellent recording sensitivity and multiple recording characteristics and a small amount of residual monomer as compared with the optical recording medium of No. 4.

  The holographic recording composition of the present invention can be used for the production of various volume hologram type optical recording media capable of high-density image recording because it can perform higher-density recording.

It is a schematic sectional drawing which shows an example of the holographic recording medium concerning 1st embodiment. It is a schematic sectional drawing which shows an example of the holographic recording medium concerning 2nd embodiment. It is explanatory drawing which shows an example of the optical system which can be used for recording and reproduction | regeneration of the information to a holographic recording medium. It is a block diagram which shows the holographic recording device which can be used in this invention. It is a figure explaining effective numerical aperture NA. It is a block diagram which shows the holographic recording device of a reflection type medium. It is a figure which illustrates the pattern of matrix information light and reference light, (a) shows the case where a numerical aperture is large, and (b) shows the case where a numerical aperture is small. The outline of the optical system of a plane wave tester is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower substrate 2 Reflective film 3 Servo pit pattern 4 Recording layer 5 Upper substrate 6 Filter layer 7 Second gap layer 8 First gap layer 12 Objective lens 13 Dichroic mirror 14 Detector 15 1/4 wavelength plate 16 Polarizing plate 17 Half Mirror 20 Holographic recording medium 21 Holographic recording medium 22 Holographic recording medium A Light incident / exit surface 10 Holographic recording device 11 Holographic recording device 31 Light source 32 Mirror 33 DMD element 36 Objective lens 40 Control device 80 Holographic recording medium 81 Substrate 82 Recording layer 83 Protective layer IB Information light OL Objective lens

Claims (7)

The holographic recording medium which has a recording layer formed from the composition for optical recording containing the compound represented with the following general formula (I).
[In general formula (I), R ¹ represents a phenyl group having an alkoxy group or a halogen group at the 2-position and the 6-position, and R ² and R ³ each independently represents an alkyl group, an aryl group or a heterocyclic group. , X represents an oxygen atom or a sulfur atom. ] The holographic recording medium according to claim 1, wherein X in the general formula (I) represents an oxygen atom. The holographic recording medium according to claim 1, wherein R ² and / or R ^{3 in the} general formula (I) represents an alkyl group. The holographic recording medium according to claim ³ , wherein R ² and R ^{3 in the} general formula (I) represent an alkyl group. The holographic recording medium according to claim 1, wherein the optical recording composition further contains a radical polymerizable compound. The holographic recording medium according to claim 1, wherein the optical recording composition further contains a thermosetting compound. The holographic recording medium according to claim 6, wherein the thermosetting compound includes a polyfunctional isocyanate and a polyfunctional alcohol.