Near-infrared photosensitive initiation system, holographic recording medium and holographic optical element

Abstract

The invention discloses a near-infrared photosensitive initiation system, a photopolymer type holographic recording medium, a holographic optical element and display equipment, and the photopolymer type holographic recording medium comprises film-forming resin, a writing monomer, the near-infrared photosensitive initiation system, a chain transfer agent, a catalyst and an additive, the film-forming resin comprises a compound with a plurality of isocyanate reactive functional groups and a polyisocyanate group compound, and the near-infrared light-sensitive initiation system comprises a near-infrared light-sensitive dye and a co-initiator. In this way, monomer polymerization can be efficiently initiated, the material cost is low, and the holographic recording performance of the photopolymer is effectively improved.

Description

Technical Field

[0001] The present application relates to the field of holographic optical technology, and in particular to a near-infrared photosensitive initiation system, a photopolymer holographic recording medium, a holographic optical element and a display device. Background Art

[0002] Eye tracking function is one of the development trends of augmented reality (AR) glasses. Projecting infrared light onto the iris to extract feature information is a common method to achieve eye tracking. By adding a volume holographic grating with diffraction function for infrared light, the integration of the common optical path of visible light and infrared light in the holographic optical waveguide system can be realized, and the infrared eye tracking module and the AR display module share the optical path. Photopolymer is the preferred recording medium for preparing volume holographic gratings. To prepare a volume holographic grating with diffraction function for near-infrared light (800-1000nm), the photopolymer needs to be able to initiate monomer polymerization under the irradiation of laser of the corresponding wavelength. However, there is currently a lack of efficient near-infrared photosensitization initiation system. Summary of the invention

[0003] Based on this, the present application provides a near-infrared photosensitive initiation system, a photopolymer holographic recording medium, a holographic optical element and a display device.

[0004] In a first aspect, the present application provides a near-infrared photosensitive initiation system, wherein the near-infrared photosensitive initiation system comprises a near-infrared photosensitive dye and a co-initiator, wherein the near-infrared photosensitive dye is selected from one of the following structural formulas:

[0005]

[0006] Wherein, R1 and R2 each independently represent a C1-C20 straight-chain alkyl group, a branched-chain alkyl group, or a cycloalkyl group.

[0007] In a second aspect, the present application provides a photopolymer holographic recording medium, which includes: a film-forming resin, a writing monomer, a near-infrared photosensitive initiation system, a chain transfer agent, a catalyst and an additive, wherein the film-forming resin includes a compound having multiple isocyanate-reactive functional groups and a polyisocyanate-based compound, and the near-infrared photosensitive initiation system is the near-infrared photosensitive initiation system described above.

[0008] In a third aspect, the present application provides a holographic optical element, wherein the raw material of the holographic optical element includes the photopolymer holographic recording medium as described above.

[0009] In a fourth aspect, the present application provides a display device, comprising the holographic optical element as described above.

[0010] The near-infrared photosensitive initiation system of the embodiment of the present application can quickly generate active species such as free radicals under the irradiation of 800-1000nm light source, thereby efficiently initiating monomer polymerization, achieving a monomer conversion rate of more than 80%, and having low material cost. The photopolymer holographic recording material with isocyanate-isocyanate reactive functional groups as film-forming resin adopts the near-infrared photosensitive initiation system, and the photopolymer holographic recording material has high photosensitivity, and the recording grating has a high diffraction efficiency (>90%). BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is the carbon-carbon double bond conversion curve of samples 1, 3, 5, and 7;

[0012] Figure 2 The diffraction efficiency growth curves of transmission and reflection holographic gratings were recorded for the photopolymer samples shown in Table 2;

[0013] Figure 3 Diffraction efficiency growth curves of transmission and reflection holographic gratings were recorded for the photopolymer samples shown in Table 3. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0015] The flowcharts shown in the accompanying drawings are only examples and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may also be decomposed, combined or partially merged, so the actual execution order may change according to actual conditions.

[0016] In the wave of the digital age, the importance of augmented reality (AR) technology has become increasingly prominent. AR glasses have greatly enriched our perception of the world. By superimposing virtual information on the real environment, we can experience and understand the world around us from a new perspective. Therefore, AR glasses play a vital role in many fields such as education, medical care, and entertainment. The development of AR glasses also promotes the progress and innovation of related industries.

[0017] Among them, eye tracking function is one of the development trends of AR glasses. Eye tracking technology can accurately track the user's eye movement, so as to obtain the user's gaze point, gaze duration, eye saccade and other eye movement indicator data. These data can be used to analyze the user's attention distribution, points of interest, etc., and provide accurate user feedback and behavior analysis for AR applications. Eye tracking technology allows users to control AR glasses through eye movements, without the need to use traditional physical interaction methods such as handles or touch screens. Users can execute commands or operations by looking at specific virtual objects or areas. This natural interaction method greatly improves the intuitiveness and convenience of the user experience. Eye tracking technology can help AR glasses achieve dynamic gaze point rendering, that is, optimize image quality according to the user's gaze point. This means that the image quality will be improved in the area where the user is looking, while the image quality can be appropriately reduced in the non-looking area to save computing resources and improve rendering efficiency.

[0018] Projecting infrared light onto the iris to extract feature information is a common method for achieving eye tracking. By adding a volume holographic grating that has a diffraction function for infrared light, the integration of the common optical path of visible light and infrared light in the holographic optical waveguide system can be achieved, and the infrared eye tracking module and the AR display module share the optical path. Photopolymer is the preferred recording medium for preparing volume holographic gratings. To prepare a volume holographic grating that has a diffraction function for infrared light, the photopolymer needs to be able to initiate monomer polymerization under the irradiation of a laser of the corresponding wavelength. However, there is currently a lack of efficient near-infrared photosensitization initiation systems.

[0019] To solve the above problems, the embodiments of the present application provide a near-infrared photosensitive initiation system, a holographic recording medium and a holographic optical element. The near-infrared photosensitive initiation system can quickly generate active species such as free radicals under the irradiation of an 800-1000nm light source, thereby efficiently initiating monomer polymerization, achieving a monomer conversion rate of more than 80%, and having low material costs. The photopolymer holographic recording material with isocyanate-isocyanate reactive functional groups as film-forming resin adopts the near-infrared photosensitive initiation system. The photopolymer holographic recording material has high photosensitivity, and the recording grating has a high diffraction efficiency (>90%).

[0020] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0021] The embodiment of the present application provides a near-infrared photosensitive initiation system, wherein the near-infrared photosensitive initiation system comprises a near-infrared photosensitive dye and a co-initiator, wherein the near-infrared photosensitive dye is selected from one of the following structural formulas:

[0022]

[0023] Among them, R1 and R2 each independently represent C1-C 20A straight chain alkyl group, a branched chain alkyl group, or a cycloalkyl group.

[0024] In some embodiments, R1 and R2 each independently represent C1-C 10 A straight chain alkyl group, a branched chain alkyl group, or a cycloalkyl group.

[0025] In some embodiments, the near-infrared photosensitizing dye is selected from one of the following structures:

[0026]

[0027] In some embodiments, the co-initiator includes an amine co-initiator. The co-initiator is used in conjunction with a near-infrared photosensitizing dye to enable the near-infrared photosensitizing initiation system to have a good photo-initiating effect. Amine co-initiators include, but are not limited to, N-phenylglycine, L-arginine, and the like.

[0028] It should be specially noted that, in addition to the near-infrared photosensitizing dye and the co-initiator, the additional addition of other organic compounds, inorganic compounds, and organic-inorganic hybrids does not affect the function of the near-infrared photosensitizing initiator system, and therefore does not depart from the protection scope of the present invention.

[0029] An embodiment of the present application provides a photopolymer holographic recording medium, which includes: a film-forming resin, a writing monomer, a near-infrared photosensitive initiation system, a chain transfer agent, a catalyst and an additive. The film-forming resin includes a compound having multiple isocyanate-reactive functional groups and a polyisocyanate-based compound, and the near-infrared photosensitive initiation system is any of the near-infrared photosensitive initiation systems described above.

[0030] In some embodiments, the content of the film-forming resin is 30%-60% by weight, for example: 30%, 35%, 40%, 42.5%, 45%, 47.5%, 50%, 55%, 60%, etc., wherein the content of the compound having multiple isocyanate-reactive functional groups (for example: multifunctional hydroxyl compounds, multifunctional thiol compounds) and the polyisocyanate-based compound can be determined according to the content of multiple isocyanate-reactive functional groups (for example: hydroxyl, thiol) in the compound having multiple isocyanate-reactive functional groups and the content of isocyanate in the polyisocyanate-based compound; the content of the writing monomer is 30%-60%, for example: 30%, 35%, 40%, 42.5%, 45%, 47.5%, 50%, 55%, 60%, etc. %, 42.5%, 45%, 47.5%, 50%, 55%, 60%, etc., the content of the near-infrared photosensitive initiator system is 0.01%-8%, for example: 0.01%, 0.05%, 1%, 3%, 5%, 6%, 7%, 8%, etc., the content of the chain transfer agent is 0.05%-5%, for example: 0.05%, 1%, 2%, 3%, 4%, 5%, etc., the content of the catalyst is 0.001%-3%, for example: 0.001%, 0.005%, 0.01%, 0.05%, 1%, 2%, 3%, etc., the content of the additive is 0.1%-10%, for example: 0.1%, 0.5%, 1%, 3%, 5%, 7%, 9%, 10%, etc.

[0031] In some embodiments, in the near-infrared photosensitive initiation system, the mass ratio of the co-initiator to the near-infrared photosensitizing dye is 0.1-10:0.0001-5.

[0032] Exemplarily, the mass ratio of the co-initiator to the near-infrared photosensitizing dye may be 0.1-10:0.001-5.

[0033] Exemplarily, the mass ratio of the co-initiator to the near-infrared photosensitizing dye may be 0.1-10:0.01-5.

[0034] Exemplarily, the mass ratio of the co-initiator to the near-infrared photosensitizing dye may be 0.1-10:0.1-5.

[0035] Exemplarily, the mass ratio of the co-initiator to the near-infrared photosensitizing dye may be 0.1-10:0.0001-0.001.

[0036] Exemplarily, the mass ratio of the co-initiator to the near-infrared photosensitizing dye may be 0.1-10:0.0001-0.01.

[0037] Exemplarily, the mass ratio of the co-initiator to the near-infrared photosensitizing dye may be 0.1-10:0.0001-0.1.

[0038] For example, the mass ratio of the co-initiator to the near-infrared photosensitizing dye may be 0.1-10:0.0001-1.

[0039] Exemplarily, the mass ratio of the co-initiator to the near-infrared photosensitizing dye may be 0.1-10:0.001-0.01.

[0040] Exemplarily, the mass ratio of the co-initiator to the near-infrared photosensitizing dye may be 0.1-10:0.001-0.1.

[0041] For example, the mass ratio of the co-initiator to the near-infrared photosensitizing dye may be 0.1-10:0.001-1.

[0042] Exemplarily, the mass ratio of the co-initiator to the near-infrared photosensitizing dye may be 0.1-10:0.01-0.1.

[0043] For example, the mass ratio of the co-initiator to the near-infrared photosensitizing dye may be 0.1-10:0.01-1.

[0044] Exemplarily, the mass ratio of the co-initiator to the near-infrared photosensitizing dye may be 0.1-10:0.1-1.

[0045] In some embodiments, the additive includes one or more of a defoamer, a leveling agent, a plasticizer, a water scavenger, a UV absorber, a light stabilizer, and an antioxidant.

[0046] In some embodiments, when the additive includes a defoaming agent, the content of the defoaming agent is no more than 3% based on the total mass of the photopolymer-type holographic recording medium.

[0047] In some embodiments, when the additive includes a leveling agent, the content of the leveling agent is no more than 3% based on the total mass of the photopolymer holographic recording medium.

[0048] In some embodiments, when the additive includes a plasticizer, the content of the plasticizer is no more than 3% based on the total mass of the photopolymer-type holographic recording medium.

[0049] In some embodiments, when the additive includes an ultraviolet absorber, the content of the ultraviolet absorber is no more than 3% based on the total mass of the photopolymer-type holographic recording medium.

[0050] In some embodiments, when the additive includes an antioxidant, the content of the antioxidant is no more than 3% based on the total mass of the photopolymer-type holographic recording medium.

[0051] In some embodiments, when the additive includes a light stabilizer, the content of the light stabilizer is no more than 3% based on the total mass of the photopolymer-type holographic recording medium.

[0052] In some embodiments, in the compound having a plurality of isocyanate-reactive functional groups, the isocyanate-reactive functional groups are hydroxyl groups and / or thiol groups.

[0053] In some embodiments, the compound having multiple isocyanate-reactive functional groups is a compound with a low refractive index and two or more hydroxyl or thiol functional groups.

[0054] In some embodiments, the low refractive index compound with two or more hydroxyl or thiol functional groups is: 2-ethyl-1,3-hexanediol, 1,2,4-butanetriol, 1,6-hexanediol, 2,5-hexanediol, 1,4-cyclohexanediol, 1,8-octanediol, 1,7-heptanediol, 1,3-butanediol, 1,5-pentanediol, 1,4-cyclohexanedimethanol, 1,3-cyclopentanediol, tetraethylene glycol, trimethylol Ethane, trimethylolpropane, glycerol, triethanolamine, polyester polyols with a molecular weight of 100 to 2000, polycarbonate polyols, polyether polyols, 2,3-dithio (2-mercapto)-1-propanethiol, 1,2-octanedithiol, 2,5-dimethylmercapto-1,4-dithiane, 1,2-butanethiol, 1,3-butanethiol, 3,7-dithia-1,9-nonanethiol, 2,3-butanethiol.

[0055] In some embodiments, the polyisocyanate-based compound is a compound with a low refractive index and having two or more isocyanate groups.

[0056] In some embodiments, the polyisocyanate-based compound is trimethylhexamethylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, (2,4,6-trioxotriazine-1,3,5(2H,4H,6H)-triyl)tris(hexamethylene)isocyanate, and dicyclohexylmethane diisocyanate.

[0057] In some embodiments, the writing monomer comprises a polymerizable monomer / oligomer.

[0058] In some embodiments, the polymerizable monomer is selected from at least one of alkenyl naphthalene compounds, alkenyl anthracene compounds, alkenyl benzene compounds, acrylic compounds, methacrylic compounds, acrylate compounds, methacrylate compounds, N-vinyl pyrrole, N-vinyl carbazole, N-vinylimidazole, N-vinyl indole, N-vinyl pyrrolidone, and trans-N-3-ynyl butenyl carbazole.

[0059] Exemplarily, the alkenylbenzene compound can be selected from: styrene, 1,1-diphenylethylene, 4-cyanostyrene, 4-methylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 2-bromostyrene, 3-bromostyrene, 4-bromostyrene, 4-nitrostyrene, 4-vinylaniline, N-4-vinylphenyl-N,N-dimethylamine, p-(chloromethyl)styrene, p-(bromomethyl)styrene, allyl phenoxyacetate, allyl phenyl carbonate, and the like.

[0060] Exemplarily, the acrylic compound can be acrylic acid and its derivatives; exemplary, the acrylic ester compound can be selected from: 2-naphthyl acrylate, 2-phenoxyethyl acrylate, phenoxyethyl acrylate, epoxy acrylate, pentachlorophenyl acrylate, pentabromophenyl acrylate, 2-naphthyl acrylate, 1,4-di(2-thionaphthyl)2-butyl acrylate, phenoxyethoxyethyl acrylate, bisphenol A diacrylate, tetrabromobisphenol A diacrylate, 2-naphthyl acrylate, 2,4,6-tribromophenyl acrylate, o-phenylphenoxyethyl acrylate, furan-2-yl acrylate, N-hydroxysuccinimide acrylate, benzyl acrylate, 4-biphenylmethanol acrylate, 3-phenoxybenzyl acrylate, quinolin-8-yl acrylate, p-chlorophenyl acrylate, p-bromophenyl acrylate, 2-phenylethyl acrylate, 2,4,6-trichlorophenyl acrylate, pentabromobenzyl acrylate, etc.

[0061] Exemplarily, the methacrylate compound can be selected from: 2-naphthyl methacrylate, 2-phenoxyethyl methacrylate, pentachlorophenyl methacrylate, pentabromophenyl methacrylate, 1,4-di(2-thionaphthyl)2-butyl methacrylate, phenoxyethoxyethyl methacrylate, bisphenol A dimethacrylate, tetrabromobisphenol A dimethacrylate, 2,4,6-tribromobenzyl methacrylate, o-phenylphenoxyethyl methacrylate, N-hydroxysuccinimide methacrylate, benzyl methacrylate, 4-biphenylmethanol. Methacrylate, 3-phenoxybenzyl methacrylate, quinolin-8-yl methacrylate, p-bromophenyl methacrylate, 2-phenylethyl methacrylate, 2,4,6-trichlorobenzyl methacrylate, pentabromobenzyl methacrylate, phenyl methacrylate, 9-anthrylmethyl methacrylate, bisphenol A glycerol dimethacrylate, 1-naphthyl methacrylate, hydroquinone monomethacrylate, 2,4,6-trichlorophenyl methacrylate, pentabromophenyl methacrylate, pentachlorophenyl methacrylate, phenoxyethyl methacrylate, etc.

[0062] For example, the alkenyl anthracene compound may be selected from 2-vinyl anthracene, 9,10-divinyl anthracene, 9-vinyl anthracene, and the like.

[0063] For example, the alkenylnaphthalene compound may be selected from 1-vinylnaphthalene, 2-vinylnaphthalene, 1-styrenenaphthalene and the like.

[0064] Further, the chain transfer agent includes but is not limited to one or more of dodecyl mercaptan, mercaptoethanol, isooctyl 3-mercaptopropionate, hexanethiol, phenylethyl mercaptan, mercaptopropionic acid, 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol, 2,4-diphenyl-4-methyl-1-pentene, 4-methyl-4H-1,2,4-triazole-3-thiol, sodium hypophosphite, carbon tetrachloride, carbon tetrabromide, etc.

[0065] Furthermore, the catalyst is a tertiary amine catalyst and an organic metal catalyst, including but not limited to triethylenediamine, bis(dimethylaminoethyl) ether, dimethylethanolamine, 2-(2-dimethylamino-ethoxy)ethanol, trimethylhydroxyethylpropylenediamine, N,N-bis(dimethylaminopropyl)isopropanolamine, dibutyltin dilaurate, stannous octoate, potassium carboxylate catalysts and bismuth carboxylate catalysts.

[0066] Furthermore, the defoamer is a silicone defoamer, such as BYK-011, BYK-012, BYK-014, BYK-023, BYK-051N, BYK-085, BYK-1610, BYK-1707, BYK-1740, BYK-1760 produced by BYK, DC65, AFE-7820 produced by Dow Corning, or a mixture of these defoamers in any proportion.

[0067] Furthermore, the leveling agent is an organosilicon surface additive, such as BYK-302, BYK-306, BYK-307, BYK-327, BYK-329, BYK-333, BYK-356, BYK-358, BYK-378, BYK-3455, BYK-3566 produced by BYK, or a mixture of these surface additives in any proportion.

[0068] Furthermore, the plasticizer is toluene, xylene, dimethylformamide, dimethylacetamide, glycerol, phthalate or a mixture of these compounds in any proportion.

[0069] Furthermore, the dehydrating agent includes but is not limited to p-toluenesulfonyl isocyanate, triethyl orthoformate, CUWR-WB20 dehydrating agent of Guangzhou Yourun Synthetic Materials Co., Ltd., ALT-201 dehydrating agent of Anxiang Elite Chemical Co., Ltd., PCCI dehydrating agent of Shanghai Ruhr Chemical Trading Co., Ltd., etc.

[0070] Further, the ultraviolet absorber includes but is not limited to 2-hydroxy-4-n-octyloxybenzophenone, 2-(5-chloro-2H-benzotriazole-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol, N-(2-ethoxyphenyl)-N'-(2-ethylphenyl)-oxalamide, 2-(2H-benzotriazole-2-yl)-p-cresol, 2-(2H-benzotriazole-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-(2H-benzotriazole-2-yl)-4,6-di-tert-amylphenol, 2-(2H-benzotriazole-2)-4,6-di(1-methyl-1-phenylethyl)phenol or a mixture of any proportion of these additives.

[0071] Furthermore, the light stabilizer includes but is not limited to light stabilizer 944, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, light stabilizer 622 or a mixture of these additives in any proportion.

[0072] Further, the antioxidant includes but is not limited to Irganox 1010, Irganox 168, Irganox 1076, Irganox 1098, Irganox MD1024, Irganox 1035, BASF liquid antioxidant 1135, Irganox B225, Irganox PS800 (DLTP), Irganox B900, Irganox 3114, Irganox 245, Irganox B215, Irganox PS-802FL, Irganox Borchors Ascinin@Special, Irganox Borchors Ascinin@P or any mixture of these additives in any proportion.

[0073] The embodiment of the present application provides a holographic optical element, wherein the raw material of the holographic optical element includes the photopolymer holographic recording medium as described above. The holographic optical element includes but is not limited to a volume holographic grating.

[0074] An embodiment of the present application provides a display device, wherein the display device includes the holographic optical element as described above.

[0075] The embodiments of the present application are described below through specific examples.

[0076] Example 1

[0077] 1 wt % of a co-initiator (N-phenylglycine was added to samples 1, 2, 5, and 6, and L-arginine was added to samples 3, 4, 7, and 8) and 0.01 wt % of a near-infrared photosensitizer were added to the monomers, wherein the near-infrared photosensitizer was selected from any one of the dyes listed in Table 1 below, and the three components were stirred to be fully mixed into a uniform prepolymer solution, which was then injected into a hollow glass mold with a thickness of 0.1 mm, and the prepolymer solution was tested using a real-time infrared spectrometer at a light source of 800-1000 nm (100 mW / cm 2 ) irradiation photopolymerization kinetic curve. Some photopolymerization kinetic curves are shown in Figure 1 As shown, it was found that different near-infrared photosensitive initiation systems can efficiently initiate monomer polymerization under light, and the relevant data are summarized in Table 1. Under low exposure intensity, more than 80% carbon-carbon double bond conversion rate can be achieved in just 100 seconds, with fast reaction speed and high monomer conversion rate.

[0078] Table 1

[0079]

[0080] Example 2 to Example 6

[0081] Examples 2 to 6 provide five types of photopolymer holographic recording media, and their raw material components are detailed in Tables 2 to 6.

[0082] The preparation of the photopolymer holographic recording medium comprises the following steps:

[0083] In a dark room, the raw material components in Table 3 were added in sequence to a 500 mL container with a stirring device, and the mixture was stirred for 15 min at room temperature. Dust and other impurities were removed through a filter with a pore size of 0.45 μm to obtain a mixed solution. The mixed solution was used to prepare a photopolymer with a thickness of 15 μm by scraping. After curing at room temperature, a holographic recording medium was obtained.

[0084] Photopolymer-type holographic recording media containing the raw material components shown in Table 2 to Table 6 were prepared in the same manner as described above.

[0085] Example 2 uses 852nm laser for holographic recording, and the recording light intensity is 10mW / cm 2 The diffraction efficiency growth curves of the transmission (2200 lines / mm) and reflection (3400 lines / mm) gratings recorded on the photopolymer sample are shown in Figure 2. Figure 2 shown.

[0086] Example 3: Holographic recording is performed using a 968 nm laser with a recording intensity of 6 mW / cm 2The diffraction efficiency growth curves of the transmission (2000 lines / mm) and reflection (3000 lines / mm) gratings recorded on the photopolymer sample are shown in Figure 2. Figure 3 Example 4 uses 879nm laser for holographic recording, and the recording light intensity is 8mW / cm 2 , the photopolymer samples recorded the diffraction efficiency of transmission (2100 lines / mm) and reflection (3300 lines / mm) gratings.

[0087] Example 5: Holographic recording is performed using a 937 nm laser with a recording intensity of 9 mW / cm 2 , the photopolymer samples recorded the diffraction efficiency of transmission (2200 lines / mm) and reflection (3300 lines / mm) gratings.

[0088] Example 6: Holographic recording is performed using a 975 nm laser with a recording light intensity of 7 mW / cm 2 , the photopolymer samples recorded the diffraction efficiency of transmission (2100 lines / mm) and reflection (3400 lines / mm) gratings.

[0089] The calculation formula of the photosensitivity of the photopolymer sample is:

[0090]

[0091] Where η is the maximum diffraction efficiency of the recorded grating, unit %, d is the sample thickness, unit cm, I is the exposure light intensity, unit mW / cm 2 , t is the exposure time required to reach the maximum diffraction efficiency, unit is s, S is the sensitivity, unit is cm / mJ.

[0092] Table 2

[0093]

[0094]

[0095] Table 3

[0096]

[0097] Table 4

[0098]

[0099]

[0100] Table 5

[0101]

[0102] Table 6

[0103]

[0104]

[0105] Test example:

[0106] The performance of the holographic recording media of Examples 2 to 6 was tested, and the results were as follows: Figure 2-3 , Table 7.

[0107] The test method includes the following steps:

[0108] Solid-state lasers with wavelengths of 405nm, 532nm, and 633nm were used as light sources. After passing through a beam expander, beam splitter, and half-wave plate, two beams with the same light intensity and a diameter of 8mm were obtained. The two beams intersected in the prepared holographic recording medium for exposure, and the light intensity was 2.91mW / cm 2 The detection light source is a 785nm wavelength solid laser that does not react with the recording medium. The detection light is incident on the exposure area from the Bragg angle. The transmitted light and diffracted light are monitored in real time by the photodetector. The single grating diffraction efficiency (η) of the photopolymer sample and the photosensitivity (S) of the recording medium are calculated by formulas (1) to (3).

[0109]

[0110] Where η is the diffraction efficiency, η max is the highest diffraction efficiency, I d is the diffracted light, I t is the transmitted light, S is the photosensitivity, E is the exposure energy, and ΔE is the exposure energy when the highest diffraction efficiency is achieved.

[0111] Table 7

[0112]

[0113] In the embodiments of the present application, the near-infrared photosensitive initiation system composed of a near-infrared photosensitive dye and a co-initiator can quickly generate free radicals with initiation activity under the irradiation of an LED, laser or other light source of 800-1000nm to initiate monomer polymerization. Under low exposure intensity, the monomer or resin to which the near-infrared photosensitive initiation system is added can achieve a monomer conversion rate of more than 80%, and has the characteristics of fast reaction speed and high monomer conversion rate. The near-infrared photosensitive initiation system in the embodiments of the present application is used to prepare a photopolymer holographic recording medium. The photopolymer sample has high photosensitivity and can record a transmission / reflection volume holographic grating with high diffraction efficiency (>90%).

[0114] It should be understood that the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0115] It should also be understood that the term “and / or” used in the specification and appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0116] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A near-infrared photosensitive initiation system, characterized in that: The near-infrared photosensitive initiation system comprises a near-infrared photosensitive dye and a co-initiator, wherein the near-infrared photosensitive dye is selected from one of the following structural formulas: Among them, R1 and R2 each independently represent C1-C 20 A straight chain alkyl group, a branched chain alkyl group, or a cycloalkyl group.

2. The near-infrared photosensitive initiation system according to claim 1, characterized in that: R1 and R2 represent C1-C independently. 10 A straight chain alkyl group, a branched chain alkyl group, or a cycloalkyl group.

3. The red light photosensitive initiation system according to claim 1, characterized in that: The near-infrared photosensitizing dye is selected from one of the following structures:

4. The red light photosensitive initiation system according to claim 1, characterized in that: The co-initiator includes an amine co-initiator.

5. A photopolymer holographic recording medium, characterized in that: The photopolymer holographic recording medium comprises: a film-forming resin, a writing monomer, a near-infrared photosensitive initiation system, a chain transfer agent, a catalyst and an additive. The film-forming resin comprises a compound having multiple isocyanate reactive functional groups and a polyisocyanate compound. The near-infrared photosensitive initiation system is the near-infrared photosensitive initiation system described in any one of claims 1 to 4.

6. The photopolymer holographic recording medium according to claim 5, characterized in that: In terms of mass percentage, the content of the film-forming resin is 30%-60%; the content of the writing monomer is 30%-60%, the content of the near-infrared photosensitive initiation system is 0.01%-8%, the content of the chain transfer agent is 0.05%-5%, the content of the catalyst is 0.001%-3%, and the content of the additive is 0.1%-10%.

7. A holographic optical element, characterized in that: The raw material of the holographic optical element comprises the photopolymer holographic recording medium as claimed in any one of claims 5 to 6.

8. A display device, characterized in that: The display device comprises the holographic optical element as claimed in claim 7.

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