Photopolymer-type holographic recording medium, volume holographic grating, optical waveguide, and device

Abstract

The invention discloses a photopolymer type holographic recording medium, a volume holographic grating, a volume holographic optical waveguide and holographic equipment, and the photopolymer type holographic recording medium comprises liquid crystal with a plurality of polymerizable groups, epoxy resin, a first photosensitive initiation system, a second photosensitive initiation system, a chain transfer agent and an additive, the polymerizable groups in the liquid crystal with a plurality of polymerizable groups are subjected to a first polymerization reaction under the action of a first photosensitive initiation system under first illumination, and the epoxy resin is subjected to a second polymerization reaction under the action of a second photosensitive initiation system under second illumination; the absorption spectrum of the first photosensitive initiation system is different from the absorption spectrum of the second photosensitive initiation system. In this way, material support can be provided for improving the average refractive index of the photopolymer, the average refractive index of the photopolymer is improved, and the photosensitive sensitivity and diffraction efficiency of the volume holographic grating are both improved.

Description

Technical Field

[0001] The present application relates to the technical field of optical functional materials, and in particular to a photopolymer holographic recording medium, a volume holographic grating, a volume holographic optical waveguide and a holographic device. Background Art

[0002] At present, the average refractive index (about 1.5) of photopolymers used in augmented reality (AR) glasses is generally low. On the one hand, in order to increase the field of view (FOV) and reduce rainbow lines, the refractive index (1.5-2.0) of the lenses used in AR glasses is relatively high. The mismatch between the average refractive index (about 1.5) of the photopolymer and the refractive index (1.5-2.0) of the lens will lead to a large critical total reflection angle in the optical waveguide, which limits the design flexibility of optical components, increases the complexity of optical path design, and is not conducive to the high-density integration of optical components. On the other hand, the refractive index difference between photopolymers and commonly used input / output couplers (such as optical fibers or other optical components) is large, and optical signals are easily refracted or Fresnel reflected at the interface, resulting in light energy loss, and may also generate stray light. The image is prone to "ghosting" when displayed, which reduces the clarity and contrast of the image and affects the user experience. Summary of the invention

[0003] Based on this, the present application provides a photopolymer holographic recording medium, a volume holographic grating, a volume holographic optical waveguide and a holographic device, which can provide material support for improving the average refractive index of the photopolymer.

[0004] In a first aspect, the present application provides a photopolymer holographic recording medium, which includes: a liquid crystal having multiple polymerizable groups, an epoxy resin, a first photosensitive initiator system, a second photosensitive initiator system, a chain transfer agent, and an additive, wherein the polymerizable groups in the liquid crystal having multiple polymerizable groups undergo a first polymerization reaction under first light and under the action of the first photosensitive initiator system, and the epoxy resin undergoes a second polymerization reaction under second light and under the action of the second photosensitive initiator system, and the absorption spectrum of the first photosensitive initiator system is different from the absorption spectrum of the second photosensitive initiator system.

[0005] In a second aspect, the present application provides a volume holographic grating, wherein the photopolymer holographic recording medium used in the volume holographic grating includes the photopolymer holographic recording medium as described above.

[0006] In a third aspect, the present application provides a volume holographic optical waveguide, wherein the volume holographic optical waveguide comprises the volume holographic grating as described above.

[0007] In a fourth aspect, the present application provides a holographic device, wherein the holographic device comprises the volume holographic optical waveguide as described above.

[0008] In the embodiment of the present application, by adding a polymerizable high refractive index liquid crystal (>1.60) to a photopolymer holographic recording medium, the liquid crystal is used as a recording component, and a high refractive index epoxy resin (>1.50) is selected as the second reaction component. The average refractive index of the photopolymer holographic recording medium can reach 1.55-2.0, which can match the refractive index (1.5-2.0) of the lenses currently used in AR glasses, which can improve the design flexibility of optical elements, facilitate the high-density integration of optical elements, and avoid the loss of light energy, stray light and "ghost" phenomenon. In addition, the photopolymer holographic recording medium can be made into 3-30μm samples with high photosensitivity, and can record transmissive and reflective volume holographic gratings with diffraction efficiency greater than 95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 : are the holographic exposure characteristic curves of Example 1 (recording wavelength 457 nm), Example 2 (recording wavelength 633 nm), and Example 3 (recording wavelength 633 nm);

[0010] Figure 2 These are the holographic exposure characteristic curves of Example 4 (recording wavelength 633 nm), Example 5 (recording wavelength 532 nm), and Example 6 (recording wavelength 532 nm). DETAILED DESCRIPTION

[0011] 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.

[0012] 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 be decomposed, combined or partially merged, so the actual execution order may change according to actual conditions.

[0013] In the subsequent description, the suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of the present application, and have no special meanings. Therefore, "module", "component" or "unit" can be used in a mixed manner.

[0014] In the digital age, augmented reality (AR) glasses provide users with a new and intuitive interactive experience by superimposing virtual information on the real world. Users do not need to hold devices, but only need to wear glasses to obtain information and perform operations anytime and anywhere, which greatly improves the convenience and immersion of information acquisition.

[0015] AR glasses based on holographic waveguide systems have the advantages of being light, portable, highly transparent, and having realistic and natural virtual images. The core optical element of the holographic waveguide system is a pair of reflective volume holographic gratings. Currently, volume holographic gratings are usually made using photopolymers.

[0016] In order to increase the field of view (FOV) and reduce rainbow patterns, the refractive index of the lenses used in AR glasses is relatively high (1.5-2.0), while the average refractive index of photopolymers (about 1.5) is generally low. The mismatch between the two will result in a larger critical total reflection angle in the optical waveguide. This means that in order to maintain the total reflection propagation of light in the waveguide, a larger incident angle is required. This limits the design flexibility of optical components and increases the complexity of optical path design, which is not conducive to the high-density integration of optical components. The refractive index difference between photopolymers and commonly used input / output couplers (such as optical fibers or other optical components) is large. When the optical signal enters the optical waveguide from the coupler or is output from the optical waveguide to the coupler, the optical signal is prone to refraction or Fresnel reflection at the interface due to the mismatch of the refractive index. This not only leads to light energy loss, but also may generate stray light, affecting the imaging quality. Due to the refraction or Fresnel reflection of the optical signal at the interface, the image is prone to "ghosting" when displayed, which will reduce the clarity and contrast of the image and affect the user experience. Therefore, it is necessary to increase the average refractive index of the photopolymer.

[0017] In order to solve the above problems, in the embodiment of the present application, by adding a polymerizable high refractive index liquid crystal (>1.60) to a photopolymer holographic recording medium, the liquid crystal is used as a recording component, and a high refractive index epoxy resin (>1.50) is selected as the second reaction component. The average refractive index of the photopolymer holographic recording medium can reach 1.55-2.0, which can match the refractive index (1.5-2.0) of the lenses currently used in AR glasses, which can improve the design flexibility of optical elements, facilitate the high-density integration of optical elements, and avoid the loss of light energy, stray light and "ghost" phenomenon. In addition, the photopolymer holographic recording medium can be made into 3-30μm samples with high photosensitivity, and can record transmissive and reflective volume holographic gratings with diffraction efficiency greater than 95%.

[0018] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0019] The embodiment of the present application provides a photopolymer holographic recording medium, which includes: a liquid crystal having multiple polymerizable groups, an epoxy resin, a first photosensitive initiator system, a second photosensitive initiator system, a chain transfer agent, and an additive. The polymerizable groups in the liquid crystal having multiple polymerizable groups undergo a first polymerization reaction under first light and under the action of the first photosensitive initiator system, and the epoxy resin undergoes a second polymerization reaction under second light and under the action of the second photosensitive initiator system. The absorption spectrum of the first photosensitive initiator system is different from the absorption spectrum of the second photosensitive initiator system.

[0020] Liquid crystals with multiple polymerizable groups can be obtained by grafting polymerizable groups on the surface of liquid crystals through chemical modification, or by directly using polymerizable liquid crystals. Compared with general polymers, liquid crystals have a relatively high refractive index. The refractive index of the polymer obtained after the polymerizable groups in the liquid crystals with multiple polymerizable groups undergo polymerization reaction will be increased due to the presence of liquid crystals.

[0021] Epoxy resin is a high molecular polymer with the molecular formula (C 11 H 12 O3) n Epoxy resin is a general term for a class of polymers containing two or more epoxy groups in the molecule. It is the polycondensation product of epichlorohydrin and bisphenol A or polyol. Due to the chemical activity of the epoxy group, it can be opened by a variety of compounds containing active hydrogen, and cured and cross-linked to form a network structure. The refractive index of epoxy resin is greater than 1.5.

[0022] The first photosensitive initiation system is used to initiate a first polymerization reaction of a polymerizable group in a liquid crystal having a plurality of polymerizable groups under first illumination. The second photosensitive initiation system is used to initiate a second polymerization reaction of an epoxy resin under second illumination. The absorption spectrum of the first photosensitive initiation system is different from the absorption spectrum of the second photosensitive initiation system, so that under the first illumination, the polymerizable groups in the liquid crystal undergo a first polymerization reaction, and the epoxy resin does not undergo a second polymerization reaction; under the second illumination, the epoxy resin undergoes a second polymerization reaction, and the polymerizable groups in the liquid crystal do not undergo a first polymerization reaction.

[0023] In the embodiment of the present application, by adding a polymerizable high refractive index liquid crystal (>1.80) to a photopolymer holographic recording medium, the liquid crystal is used as a recording component, and a high refractive index epoxy resin (>1.50) is selected as the second reaction component. The average refractive index of the photopolymer holographic recording medium can reach 1.55-2.0, which can match the refractive index (1.5-2.0) of the lenses currently used in AR glasses, which can improve the design flexibility of optical elements, facilitate the high-density integration of optical elements, and avoid the loss of light energy, stray light and "ghost" phenomenon. In addition, the photopolymer holographic recording medium can be made into 3-30μm samples with high photosensitivity, and can record transmissive and reflective volume holographic gratings with diffraction efficiency greater than 95%.

[0024] In some embodiments, the content of the liquid crystal having a plurality of polymerizable groups is 5%-60%, for example, 5%, 10%, 20%, 30%, 40%, 50%, 60%, etc., in terms of mass percentage; the content of the epoxy resin is 10%-80%, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, etc.; the content of the first photosensitive initiator system is 0.01%-8%, for example, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 3%, 5%, 7%, 8%, etc.; the content of the second The content of the photosensitive initiator system is 0.01%-8%, for example: 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8% and the like; the content of the chain transfer agent is 0.05%-5%, for example: 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5% and the like; the content of the additive is 0.1%-20%, for example: 0.1%, 0.5%, 1%, 2.5%, 5%, 7.5%, 10%, 12.5%, 15%, 17.5%, 20% and the like.

[0025] In some embodiments, the liquid crystal having a plurality of polymerizable groups comprises a polymerizable liquid crystal, and the polymerizable groups in the polymerizable liquid crystal comprise at least one of acrylate, methacrylate, allyl ether, and propargyl ether.

[0026] In some embodiments, the polymerizable liquid crystal includes at least one of the following substances:

[0027]

[0028]

[0029]

[0030]

[0031] RO includes but is not limited to:

[0032]

[0033]

[0034]

[0035] In some embodiments, the epoxy resin includes bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, hydrogenated bisphenol A epoxy resin, glycerol triglycidyl ether, n-butyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, diglycidyl ester, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, butanediol diglycidyl ether, pentanediol diglycidyl ether, glycerol triglycidyl ether, 3,4-epoxycyclohexene methyl 3,4-epoxycyclohexenoate, polyethylene glycol diglycidyl ether, diglycidyl ether, diethylene glycol diglycidyl ether, benzyl glycidyl ether, phenyl glycidyl ether, furfuryl glycidyl ether, 2-biphenyl glycidyl ether, pentaerythritol glycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, 1,4-butanediol glycidyl ether, trimethylolethane triglycidyl ether, 2-ethyl Oxyphenyl glycidyl ether, 1,2-cyclohexanediol diglycidyl ether, tetrabromobisphenol A epoxy resin, diglycidyl phthalate, glycidyl p-toluenesulfonate, glycidyl butyrate, glycidyl decanoate, glycidyl octanoate, glycidyl oleate, glycidyl stearate, glycidyl laurate, glycidyl acrylate, glycidyl tert-butyl carbonate, glycidyl palmitate, glycidyl linolenate, glycidyl linoleate, triglycidyl isocyanurate ester, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, glycidyl 4-tert-butylbenzoate, 1-benzyl-4-glycidyl piperazine, triglycidyl isocyanurate (S,S,S), diglycidyl 4,5-epoxytetrahydrophthalate, 4-hydroxybutyl acrylate glycidyl ether, 3-glycidylpropyl (dimethoxy)methylsilane, triglycidyl amino-meta-cresol, and triglycidyl p-aminophenol.

[0036] In some embodiments, the epoxy resin has a refractive index greater than 1.5 and a viscosity less than 100 mPa·s.

[0037] In some embodiments, the epoxy resin has a refractive index greater than 1.55 and a viscosity less than 1000 mPa·s.

[0038] In some embodiments, the first photosensitive initiator system includes a first photoinitiator and a dye. The first photoinitiator can be activated by visible light and initiate the first polymerization reaction of the polymerizable group. The dye can activate the first photoinitiator by energy transfer or electron transfer under the visible light.

[0039] Visible light refers to the part of the electromagnetic spectrum that can be perceived by the human eye. The visible spectrum does not have a precise range. The frequency of electromagnetic waves that can be perceived by the average human eye is between 380 and 750 THz, and the wavelength is between 780 and 400 nm. However, some people can perceive electromagnetic waves with a frequency of approximately 340 to 790 THz and a wavelength of approximately 880 to 380 nm.

[0040] Exemplarily, the mass ratio of the first photoinitiator to the dye is 0.1-10:0.0001-5.

[0041] Exemplarily, the mass ratio of the first photoinitiator to the dye is 0.1-10:0.001-5.

[0042] Exemplarily, the mass ratio of the first photoinitiator to the dye is 0.1-10:0.01-5.

[0043] Exemplarily, the mass ratio of the first photoinitiator to the dye is 0.1-10:0.1-5.

[0044] Exemplarily, the mass ratio of the first photoinitiator to the dye is 0.1-10:0.0001-0.001.

[0045] Exemplarily, the mass ratio of the first photoinitiator to the dye is 0.1-10:0.0001-0.01.

[0046] Exemplarily, the mass ratio of the first photoinitiator to the dye is 0.1-10:0.0001-0.1.

[0047] Exemplarily, the mass ratio of the first photoinitiator to the dye is 0.1-10:0.0001-1.

[0048] Exemplarily, the mass ratio of the first photoinitiator to the dye is 0.1-10:0.001-0.01.

[0049] Exemplarily, the mass ratio of the first photoinitiator to the dye is 0.1-10:0.001-0.1.

[0050] Exemplarily, the mass ratio of the first photoinitiator to the dye is 0.1-10:0.001-1.

[0051] Exemplarily, the mass ratio of the first photoinitiator to the dye is 0.1-10:0.01-0.1.

[0052] Exemplarily, the mass ratio of the first photoinitiator to the dye is 0.1-10:0.01-1.

[0053] Exemplarily, the mass ratio of the first photoinitiator to the dye is 0.1-10:0.1-1.

[0054] In some embodiments, the first photoinitiator includes at least one of aromatic ketone compounds, benzoin and its derivatives, benzil ketal, acylphosphine oxide, aryl ammonium borate, chromium salts, aryl diazonium salts, onium salts, and organic metal compounds.

[0055] In some embodiments, the first photoinitiator includes one or more of benzophenone, alkylbenzophenone, 4,4'-bis(dimethylamino)benzophenone, anthrone and halogenated benzophenone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bisacylphosphine oxide, phenyl dihydroxyacetate, camphorquinone, α-aminoalkylphenone, α,α-dialkoxyacetophenone, α-hydroxyalkylphenone, triphenylhexyl borate tetrabutylammonium, tri-(3-fluorophenyl)hexyl borate tetrabutylammonium, tri-(3-chloro-4-methylphenyl)hexyl borate tetrabutylammonium, ferrocenyl compounds, iodonium salts, sulfonium salts, hexaarylbisimidazoles, and the like.

[0056] In some embodiments, the dye includes at least one of cyanine dyes, fluorescein dyes, coumarin ketone dyes, nitrogen-containing aromatic heterocyclic compounds, aromatic amine compounds, and benzylcycloalkane ketone compounds.

[0057] In some embodiments, the dye includes one or more of new methylene blue, thionine, basic yellow, pinacol chloride, rhodamine 6G, gallocyanine, ethyl violet, Victoria blue R, lapis lazuli blue, methylene blue, Astrazon Orange G, Darrow red, pyrrole red Y, basic red 29, quinaldine red, crystal violet, ethyl violet, brilliant green, pyri11lium I, azure A, crystal violet white nitrile, malachite green white nitrile, etc.

[0058] In some embodiments, the second photosensitive initiation system includes a second photoinitiator, and the second photoinitiator can initiate a cationic ring-opening polymerization reaction of the epoxy resin under ultraviolet light.

[0059] Ultraviolet (UV) can refer to the general term for radiation with a frequency of 750THz to 30PHz in the electromagnetic spectrum, corresponding to a wavelength of 400nm to 10nm in a vacuum, which cannot cause human vision.

[0060] In some embodiments, the second photoinitiator includes at least one of an aromatic diazonium salt, a diaryl iodonium salt, a triaryl sulfonium salt, and a ferrocenium salt compound.

[0061] In some embodiments, the chain transfer agent is a thiol compound, and the chain transfer agent includes one or more of dodecyl mercaptan, mercaptoethanol, hexanethiol, phenylethyl mercaptan, 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol, 4-methyl-4H-1,2,4-triazole-3-thiol, etc.

[0062] In some embodiments, the additive includes one or more of a defoamer, a leveling agent, a plasticizer, a UV absorber, a light stabilizer, and an antioxidant.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] In some embodiments, when the additive includes an ultraviolet absorber, the content of the plasticizer is no more than 3% based on the total mass of the photopolymer-type holographic recording medium.

[0067] In some embodiments, when the additive includes an antioxidant, the content of the plasticizer is no more than 3% based on the total mass of the photopolymer-type holographic recording medium.

[0068] In some embodiments, when the additive includes a light stabilizer, the content of the plasticizer is no more than 3% based on the total mass of the photopolymer-type holographic recording medium.

[0069] In some embodiments, 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.

[0070] In some embodiments, the leveling agent is a silicone 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.

[0071] In some embodiments, the plasticizer is toluene, xylene, dimethylformamide, dimethylacetamide, glycerol, phthalate or a mixture of these compounds in any proportion.

[0072] In some embodiments, 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 any mixture of these additives in any proportion.

[0073] In some embodiments, 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 ratio.

[0074] In some embodiments, 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.

[0075] The embodiment of the present application provides a volume holographic grating, wherein the photopolymer holographic recording medium used in the volume holographic grating includes any of the photopolymer holographic recording media described above.

[0076] In some embodiments, the preparation method of the volume holographic grating includes: uniformly mixing all components of the photopolymer holographic recording medium, and uniformly preparing a layer of photopolymer film on the substrate by means of scraping, spin coating, etc. The mixed solution can also be injected into a hollow glass mold. Two beams of light are used for coherent exposure, and after the exposure is completed, the cationic ring-opening polymerization is carried out by ultraviolet light, and the volume holographic grating can be obtained after the polymerization is completed.

[0077] An embodiment of the present application provides a volume holographic optical waveguide, wherein the volume holographic optical waveguide includes the volume holographic grating as described above.

[0078] An embodiment of the present application provides a holographic device, which includes the volume holographic optical waveguide as described above.

[0079] The embodiments of the present application are described below through specific examples.

[0080] Examples 1 to 6 provide six kinds of photopolymer holographic recording media, wherein the preparation method of the photopolymer holographic recording media is to mix all components uniformly. The raw material components are shown in Tables 1 to 6.

[0081] Table 1

[0082]

[0083]

[0084] Table 2

[0085]

[0086] Table 3

[0087]

[0088]

[0089] Table 4

[0090]

[0091] Table 5

[0092]

[0093]

[0094] Table 6

[0095]

[0096] Test example:

[0097] The performance of the holographic recording media of Examples 1-6 was tested. The results are as follows: Figure 1-2 , Table 7.

[0098] The test method includes the following steps:

[0099] 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 After the holographic exposure, the 2 ) irradiated the sample for 30 minutes to fully cure the epoxy resin. The detection light source used was a 785nm wavelength solid laser that does not react with the recording medium. The detection light was incident on the exposure area from the Bragg angle. The transmitted light and diffracted light were monitored in real time by a photodetector, and the single grating diffraction efficiency (η) of the photopolymer sample and the photosensitivity (S) of the recording medium were calculated by formulas (1) to (3).

[0100]

[0101] 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.

[0102] Table 7

[0103]

[0104] In the embodiment of the present application, by adding a polymerizable high refractive index liquid crystal (>1.60) to the photopolymer, the liquid crystal is used as a recording component, and a higher refractive index epoxy resin (>1.50) is selected as the second reaction component, the average refractive index of the photopolymer can reach 1.55-2.0, which can match the refractive index of the lenses currently used in AR glasses (1.5-2.0). The design flexibility of optical components is improved, which is conducive to the high-density integration of optical components, while avoiding the loss of light energy and the generation of stray light and "ghost" phenomena. In addition, the photopolymer can be made into 3-30μm samples with high photosensitivity, and can record transmissive and reflective volume holographic gratings with diffraction efficiency greater than 95%.

[0105] 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.

[0106] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0107] 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 photopolymer holographic recording medium, characterized in that: The photopolymer holographic recording medium comprises: a liquid crystal having a plurality of polymerizable groups, an epoxy resin, a first photosensitive initiation system, a second photosensitive initiation system, a chain transfer agent and an additive, wherein the polymerizable groups in the liquid crystal having a plurality of polymerizable groups undergo a first polymerization reaction under first light irradiation and the action of the first photosensitive initiation system, and the epoxy resin undergoes a second polymerization reaction under second light irradiation and the action of the second photosensitive initiation system, and the absorption spectrum of the first photosensitive initiation system is different from the absorption spectrum of the second photosensitive initiation system.

2. The photopolymer holographic recording medium according to claim 1, wherein: In terms of mass percentage, the content of the liquid crystal having multiple polymerizable groups is 5%-60%, the content of the epoxy resin is 10%-80%, the content of the first photosensitive initiator system is 0.01%-8%, the content of the second photosensitive initiator system is 0.01%-8%, the content of the chain transfer agent is 0.05%-5%, and the content of the additive is 0.1%-20%.

3. The photopolymer holographic recording medium according to claim 1, wherein: The liquid crystal having a plurality of polymerizable groups comprises a polymerizable liquid crystal, and the polymerizable groups in the polymerizable liquid crystal comprise at least one of acrylate, methacrylate, allyl ether, and propargyl ether.

4. The photopolymer holographic recording medium according to claim 3, characterized in that: The polymerizable liquid crystal includes at least one of the following substances: RO includes but is not limited to:

5. The photopolymer holographic recording medium according to claim 1, wherein: The epoxy resin includes bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, hydrogenated bisphenol A epoxy resin, glycerol triglycidyl ether, n-butyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, diglycidyl ester, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, butanediol diglycidyl ether, pentanediol diglycidyl ether, glycerol triglycidyl ether, 3,4-epoxycyclohexenemethyl-3,4- Epoxy cyclohexene ester, polyethylene glycol diglycidyl ether, diglycidyl ether, diethylene glycol diglycidyl ether, benzyl glycidyl ether, phenyl glycidyl ether, furfuryl glycidyl ether, 2-biphenyl glycidyl ether, pentaerythritol glycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, 1,4-butanediol glycidyl ether, trimethylolethane triglycidyl ether, 2-ethoxyphenyl Glycidyl ether, 1,2-cyclohexanediol diglycidyl ether, tetrabromobisphenol A epoxy resin, diglycidyl phthalate, glycidyl p-toluenesulfonate, glycidyl butyrate, glycidyl decanoate, glycidyl octanoate, glycidyl oleate, glycidyl stearate, glycidyl laurate, glycidyl acrylate, glycidyl versatate, glycidyl palmitate, glycidyl linolenate, glycidyl linoleate, triglycidyl isocyanurate, At least one of hexahydrophthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, 4-tert-butylbenzoic acid glycidyl ester, 1-benzyl-4-glycidyl piperazine, isocyanuric acid (S,S,S) triglycidyl ester, 4,5-epoxytetrahydrophthalic acid diglycidyl ester, 4-hydroxybutyl acrylate glycidyl ether, 3-glycidylpropyl (dimethoxy)methylsilane, triglycidylamino-meta-cresol, and triglycidylpara-aminophenol.

6. The photopolymer holographic recording medium according to claim 1, wherein: The first photosensitive initiation system includes a first photoinitiator and a dye, wherein the first photoinitiator can be activated by visible light irradiation and initiate the polymerizable group to undergo a first polymerization reaction, and the dye can activate the first photoinitiator by energy transfer or electron transfer under the visible light irradiation; The second photosensitive initiation system includes a second photoinitiator, and the second photoinitiator can initiate a cationic ring-opening polymerization reaction of the epoxy resin under ultraviolet light irradiation.

7. The photopolymer holographic recording medium according to claim 6, wherein: The first photoinitiator includes aromatic ketone compounds, benzoin and its derivatives, benzil ketal, acylphosphine oxide, aryl ammonium borate, chromium salt, aryl diazonium salt, onium salt, organometallic compound or any mixture of these compounds; The dyes include cyanine dyes, fluorescein dyes, coumarin ketone dyes, nitrogen-containing aromatic heterocyclic compounds, aromatic amine compounds, benzylcycloalkane ketone compounds or any mixture of these compounds; The second photoinitiator includes aromatic diazonium salts, diaryliodonium salts, triarylsulfonium salts, ferrocenium salt compounds or mixtures of these compounds in any proportion.

8. A volume holographic grating, characterized in that: The photopolymer holographic recording medium used in the volume holographic grating includes the photopolymer holographic recording medium according to any one of claims 1-7.

9. A volume holographic optical waveguide, characterized in that: The volume holographic optical waveguide comprises the volume holographic grating as claimed in claim 8.

10. A holographic device, characterized in that: The holographic device comprises the volume holographic optical waveguide of claim 9.

Images