Near-infrared photoinitiating system, holographic recording medium and holographic optical element

Abstract

Disclosed in the present application are a near-infrared photoinitiating system, a photopolymer-type holographic recording medium, a holographic optical element and a display device. The near-infrared photoinitiating system comprises a near-infrared photosensitive 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 a photopolymer is effectively improved.

Description

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

[0001] This application claims priority to Chinese Patent Application No. 2024117500342, filed on November 29, 2024, entitled “Near-infrared photosensitive initiation system, holographic recording medium and holographic optical element”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of holographic optics technology, and in particular to a near-infrared photosensitive initiation system, a photopolymer-type holographic recording medium, holographic optical elements, and display devices. Background Technology

[0003] Eye-tracking functionality is one of the trends in the development of augmented reality (AR) glasses. Projecting infrared light onto the iris for feature extraction is a common method for eye tracking. By adding a volume holographic grating with infrared diffraction capabilities, a shared optical path for both visible and infrared light can be achieved in the holographic waveguide system, allowing the infrared eye-tracking module and the AR display module to share the same optical path. Photopolymers are the preferred recording medium for fabricating volume holographic gratings. To fabricate a volume holographic grating with near-infrared (800-1000nm) diffraction capabilities, the photopolymer needs to be able to initiate monomer polymerization under laser irradiation of the corresponding wavelength. However, currently, there is a lack of highly efficient near-infrared photosensitive initiation systems. Summary of the Invention

[0004] Based on this, this application provides a near-infrared photosensitive initiation system, a photopolymer-type holographic recording medium, a holographic optical element, and a display device.

[0005] In a first aspect, this application provides a near-infrared photosensitive initiation system, the near-infrared photosensitive initiation system comprising a near-infrared photosensitive dye and a co-initiator, wherein the near-infrared photosensitive dye is selected from one of the following general structural formulas:

[0006] Among them, R1 and R2 each independently represent C1-C 20 Straight-chain alkyl, branched alkyl, and cycloalkyl.

[0007] Secondly, this application provides a photopolymer-type 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 additives. The film-forming resin includes compounds having multiple isocyanate reactive functional groups and polyisocyanate group compounds. The near-infrared photosensitive initiation system is the near-infrared photosensitive initiation system described above.

[0008] Thirdly, this application provides a holographic optical element, the raw material of which includes the photopolymer type holographic recording medium as described above.

[0009] Fourthly, this application provides a display device, which includes the holographic optical element described above.

[0010] The near-infrared photosensitive initiation system of this application embodiment can rapidly generate active species such as free radicals under irradiation with an 800-1000 nm light source, thereby efficiently initiating monomer polymerization and achieving a monomer conversion rate of over 80% with low material cost. This photopolymer holographic recording material, using isocyanate-isocyanate reactive functional groups as the film-forming resin, employs this near-infrared photosensitive initiation system. This photopolymer holographic recording material exhibits high photosensitivity and a recording grating with high diffraction efficiency (>90%). Attached Figure Description

[0011] Figure 1 shows the carbon-carbon double bond conversion curves for samples 1, 3, 5, and 7.

[0012] Figure 2 shows the diffraction efficiency growth curves of the photopolymer samples recording transmission and reflection holographic gratings, as shown in Table 2.

[0013] Figure 3 shows the diffraction efficiency growth curves of the photopolymer samples recording transmission and reflection holographic gratings, as shown in Table 3. Detailed Implementation

[0014] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0015] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0016] In the wave of the digital age, the importance of Augmented Reality (AR) technology is becoming increasingly prominent. AR glasses greatly enrich our perception of the world. By overlaying virtual information onto the real environment, we can experience and understand the world around us from a completely new perspective. Therefore, AR glasses play a vital role in many fields such as education, healthcare, and entertainment, and their development is also driving progress and innovation in related industries.

[0017] Eye-tracking is one of the development trends in AR glasses. Eye-tracking technology can accurately track a user's eye movements, thereby acquiring eye movement metrics such as gaze point, gaze duration, and saccades. This data can be used to analyze user attention allocation and points of interest, providing accurate user feedback and behavioral analysis for AR applications. Eye-tracking technology allows users to control AR glasses through eye movements, eliminating the need for traditional physical interaction methods such as controllers or touchscreens. Users can execute commands or operations by looking at specific virtual objects or areas; this natural interaction method greatly enhances the intuitiveness and convenience of the user experience. Eye-tracking technology can help AR glasses achieve dynamic gaze-based rendering, optimizing image quality based on the user's gaze point. This means that image quality is improved in areas the user is looking at, while image quality can be appropriately reduced in non-gaze areas to save computing resources and improve rendering efficiency.

[0018] Projecting infrared light onto the iris for feature extraction is a common method for eye tracking. By adding a volume holographic grating with infrared diffraction capabilities, a shared optical path for both visible and infrared light can be achieved in a holographic waveguide system, allowing the infrared eye tracking module and the AR display module to share the same optical path. Photopolymers are the preferred recording medium for fabricating volume holographic gratings. To fabricate a volume holographic grating with infrared diffraction capabilities, the photopolymer needs to be able to initiate monomer polymerization under laser irradiation of the corresponding wavelength. However, currently, there is a lack of highly efficient near-infrared photosensitive initiation systems.

[0019] To address the aforementioned challenges, this application provides a near-infrared photosensitive initiation system, a holographic recording medium, and a holographic optical element. This near-infrared photosensitive initiation system can rapidly generate free radicals and other reactive species under 800-1000nm light source irradiation, thereby efficiently initiating monomer polymerization and achieving a monomer conversion rate of over 80%, while maintaining low material cost. This photopolymer-type holographic recording material, using isocyanate-isocyanate reactive functional groups as the film-forming resin, employs this near-infrared photosensitive initiation system. This photopolymer-type holographic recording material exhibits high photosensitivity, and the recording grating possesses high diffraction efficiency (>90%).

[0020] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0021] This application provides a near-infrared photosensitive initiation system, which includes a near-infrared photosensitive dye and a co-initiator. The near-infrared photosensitive dye is selected from one of the following general structural formulas:

[0022] Among them, R1 and R2 each independently represent C1-C 20 Straight-chain alkyl, branched alkyl, and cycloalkyl.

[0023] In some embodiments, R1 and R2 each independently represent C1-C 10 Straight-chain alkyl, branched alkyl, and cycloalkyl.

[0024] In some embodiments, the near-infrared photosensitive dye is selected from one of the following structures:

[0025] In some embodiments, the co-initiator includes amine co-initiators. When used in conjunction with near-infrared photosensitive dyes, the co-initiator can enhance the photoinitiation effect of the near-infrared photosensitive initiation system. Amine co-initiators include, but are not limited to, N-phenylglycine and L-arginine.

[0026] It should be noted that, apart from the near-infrared photosensitive dye and the co-initiator, the addition of other organic compounds, inorganic compounds, or organic-inorganic hybrids does not affect the function of the near-infrared photosensitive initiation system, and therefore does not deviate from the scope of protection of this application.

[0027] This application provides a photopolymer-type holographic recording medium, which includes: a film-forming resin, a writing monomer, a near-infrared photoinitiating system, a chain transfer agent, a catalyst, and additives. The film-forming resin includes compounds having multiple isocyanate reactive functional groups and polyisocyanate group compounds. The near-infrared photoinitiating system is any of the near-infrared photoinitiating systems described above.

[0028] In some embodiments, the content of the film-forming resin, by weight percentage, is 30%-60%, for example: 30%, 35%, 40%, 42.5%, 45%, 47.5%, 50%, 55%, 60%, etc., wherein the content of compounds having multiple isocyanate reactive functional groups (e.g., polyfunctional hydroxyl compounds, polyfunctional thiol compounds) and polyisocyanate group compounds can be determined based on the content of multiple isocyanate reactive functional groups (e.g., hydroxyl, thiol) in the compounds having multiple isocyanate reactive functional groups and the isocyanate content in the polyisocyanate group compounds; the content of the writing monomer is 30%-60%, for example: 30%, 35%, 40%, etc. The near-infrared photosensitive initiation system has a content of 0.01%-8%, such as 0.01%, 0.05%, 1%, 3%, 5%, 6%, 7%, 8%, etc.; the chain transfer agent has a content of 0.05%-5%, such as 0.05%, 1%, 2%, 3%, 4%, 5%, etc.; the catalyst has a content of 0.001%-3%, such as 0.001%, 0.005%, 0.01%, 0.05%, 1%, 2%, 3%, etc.; and the additive has a content of 0.1%-10%, such as 0.1%, 0.5%, 1%, 3%, 5%, 7%, 9%, 10%, etc.

[0029] In some embodiments, in the near-infrared photoinitiating system, the mass ratio of the co-initiator to the near-infrared photosensitive dye is 0.1-10:0.0001-5.

[0030] For example, the mass ratio of the co-initiator to the near-infrared photosensitive dye can be 0.1-10:0.001-5.

[0031] For example, the mass ratio of the co-initiator to the near-infrared photosensitive dye can be 0.1-10:0.01-5.

[0032] For example, the mass ratio of the co-initiator to the near-infrared photosensitive dye can be 0.1-10:0.1-5.

[0033] For example, the mass ratio of the co-initiator to the near-infrared photosensitive dye can be 0.1-10:0.0001-0.001.

[0034] For example, the mass ratio of the co-initiator to the near-infrared photosensitive dye can be 0.1-10:0.0001-0.01.

[0035] For example, the mass ratio of the co-initiator to the near-infrared photosensitive dye can be 0.1-10:0.0001-0.1.

[0036] For example, the mass ratio of the co-initiator to the near-infrared photosensitive dye can be 0.1-10:0.0001-1.

[0037] For example, the mass ratio of the co-initiator to the near-infrared photosensitive dye can be 0.1-10:0.001-0.01.

[0038] For example, the mass ratio of the co-initiator to the near-infrared photosensitive dye can be 0.1-10:0.001-0.1.

[0039] For example, the mass ratio of the co-initiator to the near-infrared photosensitive dye can be 0.1-10:0.001-1.

[0040] For example, the mass ratio of the co-initiator to the near-infrared photosensitive dye can be 0.1-10:0.01-0.1.

[0041] For example, the mass ratio of the co-initiator to the near-infrared photosensitive dye can be 0.1-10:0.01-1.

[0042] For example, the mass ratio of the co-initiator to the near-infrared photosensitive dye can be 0.1-10:0.1-1.

[0043] In some embodiments, the additives include one or more of defoamers, leveling agents, plasticizers, dehydrating agents, ultraviolet absorbers, light stabilizers, and antioxidants.

[0044] In some embodiments, when the additive includes a defoamer, the content of the defoamer does not exceed 3% based on the total mass of the photopolymer holographic recording medium.

[0045] In some embodiments, when the additive includes a leveling agent, the leveling agent content does not exceed 3% based on the total mass of the photopolymer holographic recording medium.

[0046] In some embodiments, when the additive includes a plasticizer, the content of the plasticizer does not exceed 3% based on the total mass of the photopolymer-type holographic recording medium.

[0047] In some embodiments, when the additive includes an ultraviolet absorber, the content of the ultraviolet absorber does not exceed 3% based on the total mass of the photopolymer-type holographic recording medium.

[0048] In some embodiments, when the additive includes an antioxidant, the content of the antioxidant does not exceed 3% based on the total mass of the photopolymer holographic recording medium.

[0049] In some embodiments, when the additive includes a light stabilizer, the content of the light stabilizer does not exceed 3% based on the total mass of the photopolymer holographic recording medium.

[0050] In some embodiments, in the compound having a plurality of isocyanate reactive functional groups, the isocyanate reactive functional groups are hydroxyl and / or mercapto groups.

[0051] In some embodiments, the compound having a plurality of isocyanate reactive functional groups is a low refractive index compound having two or more hydroxyl or mercapto functional groups.

[0052] In some embodiments, the low-refractive-index compound having two or more hydroxyl or mercapto 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-cyclohexanediol, 1,3-cyclopentanediol, tetraethylene glycol, trihydroxymethyl Ethane, trimethylolpropane, glycerol, triethanolamine, polyester polyols with a molecular weight of 100-2000, polycarbonate polyols, polyether polyols, 2,3-dithio(2-mercapto)-1-propanethiol, 1,2-octanedithiol, 2,5-dimethylmercapto-1,4-dithiane, 1,2-butanedithiol, 1,3-butanedithiol, 3,7-dithia-1,9-nonanedithiol, 2,3-butanedithiol.

[0053] In some embodiments, the polyisocyanate compound is a low-refractive-index compound having two or more isocyanate groups.

[0054] In some embodiments, the polyisocyanate group compound is: trimethylhexamethylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, (2,4,6-trioxotriazine-1,3,5(2H,4H,6H)-triyl)tri(hexamethylene)isocyanate, or dicyclohexylmethane diisocyanate.

[0055] In some embodiments, the writing monomer comprises a polymerizable monomer / oligomer.

[0056] In some embodiments, the polymerizable monomer is selected from at least one of alkenylnaphthalene compounds, alkenylanthracene compounds, alkenylbenzene compounds, acrylic acid compounds, methacrylic acid compounds, acrylate compounds, methacrylate compounds, N-vinylpyrrole, N-vinylcarbazole, N-vinylimidazol, N-vinylindole, N-vinylpyrrolidone, and trans-N-3-yntynebutenylcarbazole.

[0057] For example, the alkenylbenzene compound may be selected from: styrene, 1,1-stilbene, 4-cyanostrene, 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, etc.

[0058] Exemplarily, the acrylic compound can be acrylic acid and its derivatives; exemplarily, the acrylate compound can be selected from: 2-naphthyl acrylate, 2-phenoxyethyl acrylate, phenoxyethyl acrylate, epoxy acrylate, pentachlorophenyl acrylate, pentabromophenyl acrylate, 2-naphthyl acrylate, 1,4-bis(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, quinoline-8-yl acrylate, p-chlorophenyl acrylate, p-bromophenyl acrylate, 2-phenylethyl acrylate, 2,4,6-trichlorophenyl acrylate, pentabromobenzyl acrylate, etc.

[0059] For example, the methacrylate compound may be selected from: 2-naphthylmethacrylate, 2-phenoxyethylmethacrylate, pentachlorophenylmethacrylate, pentabromophenylmethacrylate, 1,4-di(2-thionaphthyl)-2-butyl methacrylate, phenoxyethoxyethyl methacrylate, bisphenol A dimethacrylate, tetrabromobisphenol A dimethacrylate, 2,4,6-tribromophenylmethacrylate, o-phenylphenoxyethyl methacrylate, N-hydroxysuccinimide methacrylate, benzyl methacrylate, and 4-biphenylmethanol. Methacrylates, 3-phenoxybenzyl methacrylate, quinoline-8-yl methacrylate, p-bromophenyl methacrylate, 2-phenylethyl methacrylate, 2,4,6-trichlorobenzyl methacrylate, pentabromobenzyl methacrylate, phenyl methacrylate, 9-anthraylmethyl methacrylate, bisphenol A glycerol dimethacrylate, 1-naphthyl methacrylate, hydroquinone monomethacrylate, 2,4,6-trichlorophenyl methacrylate, pentabromophenyl methacrylate, pentachlorophenyl methacrylate, phenoxyethyl methacrylate, etc.

[0060] For example, the alkenyl anthracene compound may be selected from 2-vinylanthracene, 9,10-divinylanthracene, 9-vinylanthracene, etc.

[0061] For example, the alkenyl naphthalene compound may be selected from 1-vinylnaphthalene, 2-vinylnaphthalene, 1-styrene naphthalene, etc.

[0062] Furthermore, the chain transfer agent includes, but is not limited to, one or more of the following: dodecyl mercaptoethanol, isooctyl 3-mercaptopropionate, hexamethylene mercaptoethanol, phenylethyl mercaptoethanol, 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, and carbon tetrabromide.

[0063] Furthermore, the catalyst is a tertiary amine catalyst and an organometallic catalyst, including but not limited to triethylenediamine, bis(dimethylaminoethyl) ether, dimethylethanolamine, 2-(2-dimethylamino-ethoxy)ethanol, trimethylhydroxyethylpropanediamine, N,N-bis(dimethylaminopropyl)isopropanolamine, dibutyltin dilaurate, stannous octoate, potassium carboxylate catalysts, and bismuth carboxylate catalysts.

[0064] Furthermore, the defoamer is an organosilicone defoamer, such as BYK-011, BYK-012, BYK-014, BYK-023, BYK-051N, BYK-085, BYK-1610, BYK-1707, BYK-1740, BYK-1760 manufactured by BYK Corporation, DC65 and AFE-7820 manufactured by Dow Corning Incorporated, or any mixture of these defoamers in any proportion.

[0065] 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, or any mixture of these surface additives manufactured by BYK Corporation.

[0066] Furthermore, the plasticizer is toluene, xylene, dimethylformamide, dimethylacetamide, glycerol, phthalate, or any mixture of these compounds in any proportion.

[0067] Furthermore, the dehydrating agents include, but are not limited to, p-toluenesulfonyl isocyanate, triethyl orthoformate, CUWR-WB20 dehydrating agent from Guangzhou Yourun Synthetic Materials Co., Ltd., ALT-201 dehydrating agent from Anxiang Elite Chemical Co., Ltd., and PCCI dehydrating agent from Shanghai Luer Chemical Trading Co., Ltd.

[0068] Furthermore, the ultraviolet absorber includes, but is not limited to, 2-hydroxy-4-n-octyloxybenzophenone, 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol, N-(2-ethoxyphenyl)-N'-(2-ethylphenyl)-ethylenediamide, 2-(2H-benzotriazol-2-yl)-p-cresol, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-(2H-benzotriazol-2-yl)-4,6-dipentylphenol, 2-(2H-benzotriazol-2)-4,6-di(1-methyl-1-phenylethyl)phenol, or any mixture of these additives in any proportion.

[0069] 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 any mixture of these additives in any proportion.

[0070] Furthermore, the antioxidants include, but are 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.

[0071] This application provides a holographic optical element, the raw material of which includes the photopolymer-type holographic recording medium as described above. The holographic optical element includes, but is not limited to, a volume holographic grating.

[0072] This application provides a display device, which includes the holographic optical element described above.

[0073] The embodiments of this application will be described below through specific examples.

[0074] Example 1

[0075] Add 1 wt% co-initiator (N-phenylglycine added to samples 1, 2, 5, and 6, and L-arginine added to samples 3, 4, 7, and 8) and 0.01 wt% near-infrared photosensitive dye to the monomer. The near-infrared photosensitive dye is selected from any one of the dyes listed in Table 1 below. Stir to thoroughly mix the three components into a homogeneous prepolymer solution, pour it into a 0.1 mm thick hollow glass mold, and use a real-time infrared spectrometer to test the prepolymer solution at a light source of 800-1000 nm (100 mW / cm²). 2 Photopolymerization kinetics curves under irradiation. Some photopolymerization kinetic curves are shown in Figure 1. It was found that different near-infrared photoinitiating systems can efficiently initiate monomer polymerization under irradiation. Relevant data are summarized in Table 1. Under low exposure intensity, a carbon-carbon double bond conversion rate of over 80% can be achieved in just 100 seconds, demonstrating fast reaction speed and high monomer conversion rate.

[0076] Table 1

[0077] Examples 2 to 6

[0078] Examples 2 to 6 provide five photopolymer-type holographic recording media, the raw material components of which are detailed in Tables 2-6.

[0079] The preparation of photopolymer-based holographic recording media includes the following steps:

[0080] In a darkroom, the raw material components listed in Table 3 are added sequentially to a 500mL container equipped with a stirrer. The mixture is stirred thoroughly at room temperature for 15 minutes. Dust and other impurities are removed by passing the mixture through a 0.45-micron filter to obtain a mixed solution. The mixed solution is then coated to prepare a photopolymer with a thickness of 15μm. After curing at room temperature, a holographic recording medium can be obtained.

[0081] Photopolymer-type holographic recording media containing the raw material components listed in Tables 2-6 were prepared using the same preparation method described above.

[0082] Example 2 uses an 852nm laser for holographic recording, with a recording light intensity of 10mW / cm². 2 Figure 2 shows the diffraction efficiency growth curves of the photopolymer sample recording the transmission (2200 lines / mm) and reflection (3400 lines / mm) gratings.

[0083] Example 3 uses a 968nm laser for holographic recording, with a recording light intensity of 6mW / cm². 2Figure 3 shows the diffraction efficiency growth curves of the photopolymer sample recording transmission (2000 lines / mm) and reflection (3000 lines / mm) gratings. Example 4 uses an 879nm laser for holographic recording with a recording intensity of 8mW / cm². 2 The diffraction efficiency of transmission (2100 lines / mm) and reflection (3300 lines / mm) gratings was recorded on photopolymer samples.

[0084] Example 5 uses a 937nm laser for holographic recording, with a recording light intensity of 9mW / cm². 2 The diffraction efficiency of transmission (2200 lines / mm) and reflection (3300 lines / mm) gratings was recorded on photopolymer samples.

[0085] Example 6 uses a 975nm laser for holographic recording, with a recording light intensity of 7mW / cm². 2 The diffraction efficiency of transmission (2100 lines / mm) and reflection (3400 lines / mm) gratings was recorded on photopolymer samples.

[0086] The formula for calculating the photosensitivity of photopolymer samples is:

[0087] In the formula, η is the maximum diffraction efficiency of the recording grating (%), d is the sample thickness (cm), and I is the exposure light intensity (mW / cm). 2 t is the exposure time required to reach maximum diffraction efficiency in seconds, and S is the sensitivity in cm / mJ.

[0088] Table 2

[0089] Table 3

[0090] Table 4

[0091] Table 5

[0092] Table 6

[0093] Experimental example:

[0094] The performance of the holographic recording media of Examples 2 to 6 was tested, and the results are shown in Figures 2-3 and Table 7.

[0095] The testing method includes the following steps:

[0096] Solid-state lasers with wavelengths of 405 nm, 532 nm, and 633 nm were used as light sources. After passing through a beam expander, beam splitter, and half-wave plate, two beams with the same intensity and a diameter of 8 mm were obtained. The two beams were intersected and exposed within the prepared holographic recording medium, with a light intensity of 2.91 mW / cm². 2 The detection light source is a 785nm wavelength solid-state 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 a 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).

[0097] In the formula, η is the diffraction efficiency, η max For the highest diffraction efficiency, I d For diffracted light, I t S represents transmitted light, S represents photosensitivity, E represents exposure energy, and ΔE represents the exposure energy required to achieve the highest diffraction efficiency.

[0098] Table 7

[0099] In this embodiment, the near-infrared photoinitiating system, composed of a near-infrared photosensitive dye and a co-initiator, can rapidly generate free radicals with initiation activity under irradiation from LEDs, lasers, or other light sources at 800-1000 nm, initiating monomer polymerization. At low exposure intensities, monomers or resins with this near-infrared photoinitiating system can achieve a monomer conversion rate of over 80%, exhibiting characteristics of fast reaction speed and high monomer conversion rate. When the near-infrared photoinitiating system from this embodiment is used to prepare photopolymer-type holographic recording media, the photopolymer sample exhibits high photosensitivity and can record high diffraction efficiency (>90%) transmission / reflection volume holographic gratings.

[0100] It should be understood that the terminology used in this application specification is for the purpose of describing particular embodiments only and is not intended to limit the application.

[0101] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0102] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and such modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A near-infrared photoinitiating system comprising a near-infrared photodye selected from one of the following general structures: ###0001### ###0002### and a co-initiator. ​ wherein R1, R2each independently represents a linear, branched and cyclic alkyl group having 1 to 6 carbon atoms. 20 R1, R2each independently represents a linear, branched and cyclic alkyl group having 1 to 6 carbon atoms.

2. The near infrared photoinitiating system according to claim 1, wherein, R1 and R2 each independently represent C1-C 10 Straight-chain alkyl, branched alkyl, and cycloalkyl.

3. The near infrared photoinitiating system according to claim 1, wherein, The near infrared photosensitive dye is selected from one of the following structures:

4. The near infrared photoinitiating system according to claim 1, wherein, The co-initiators include amine co-initiators.

5. The near infrared photoinitiating system according to claim 4, wherein, The amine co-initiator includes at least one of N-phenylglycine and L-arginine.

6. A photopolymer-type holographic recording medium, the photopolymer-type holographic recording medium comprising: The film-forming resin, writing monomer, near-infrared photoinitiating system, chain transfer agent, catalyst, and additives, wherein the film-forming resin includes compounds having multiple isocyanate reactive functional groups and polyisocyanate group compounds, and the near-infrared photoinitiating system is the near-infrared photoinitiating system according to any one of claims 1-5.

7. The photopolymer type holographic recording medium according to claim 6, wherein, The film-forming resin comprises 30%-60% by mass percentage; the writing monomer comprises 30%-60% by mass percentage; the near-infrared photoinitiator comprises 0.01%-8% by mass percentage; the chain transfer agent comprises 0.05%-5% by mass percentage; the catalyst comprises 0.001%-3% by mass percentage; and the additive comprises 0.1%-10% by mass percentage.

8. The photopolymer type holographic recording medium according to claim 6, wherein, In the near-infrared photosensitive initiation system, the mass ratio of the co-initiator to the near-infrared photosensitive dye is 0.1-10:0.0001-5.

9. The photopolymer type holographic recording medium according to claim 6, wherein, The additives include one or more of the following: defoamers, leveling agents, plasticizers, dehydrating agents, ultraviolet absorbers, light stabilizers, and antioxidants.

10. The photopolymer type holographic recording medium according to claim 9, wherein, When the additive includes an antifoaming agent, the content of the antifoaming agent shall not exceed 3% based on the total mass of the photopolymer holographic recording medium; And / or, when the additive includes a leveling agent, the leveling agent content does not exceed 3% based on the total mass of the photopolymer holographic recording medium; And / or, when the additive includes a plasticizer, the content of the plasticizer shall not exceed 3% based on the total mass of the photopolymer-type holographic recording medium; And / or, when the additive includes an ultraviolet absorber, the content of the ultraviolet absorber shall not exceed 3% based on the total mass of the photopolymer-type holographic recording medium; And / or, when the additive includes an antioxidant, the content of the antioxidant shall not exceed 3% based on the total mass of the photopolymer holographic recording medium; And / or, when the additive includes a light stabilizer, the content of the light stabilizer does not exceed 3% based on the total mass of the photopolymer holographic recording medium.

11. The photopolymer type holographic recording medium according to claim 6, wherein, In the compound having multiple isocyanate reactive functional groups, the isocyanate reactive functional groups are hydroxyl and / or thiol groups.

12. The photopolymer type holographic recording medium according to claim 6, wherein, The writing monomer includes polymerizable monomers.

13. The photopolymer type holographic recording medium according to claim 12, wherein, The polymerizable monomer is selected from at least one of alkenylnaphthalene compounds, alkenylanthracene compounds, alkenylbenzene compounds, acrylic acid compounds, methacrylic acid compounds, acrylate compounds, methacrylate compounds, N-vinylpyrrole, N-vinylcarbazole, N-vinylimidazol, N-vinylindole, N-vinylpyrrolidone, and trans-N-3-yntynebutenylcarbazole.

14. A holographic optical element, wherein the raw material of the holographic optical element includes the photopolymer type holographic recording medium as described in any one of claims 6-13.

15. A display device comprising the holographic optical element as claimed in claim 14.

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