Holographic polymer dispersed liquid crystal material, volume holographic optical waveguide device and preparation method thereof

Abstract

The present invention provides a holographic polymer dispersed liquid crystal material, a volume holographic optical waveguide device and a preparation method thereof. By adjusting the composition ratio of the holographic polymer dispersed liquid crystal material and the process parameters in the preparation process of the holographic optical waveguide device, a holographic optical waveguide device with high diffraction efficiency and low haze is prepared. Specifically, three types of monomers with different functionalities are introduced into the holographic polymer dispersed liquid crystal material: the first monomer is selected from lauric acid acrylate, cyclotrimethylolpropane formal acrylate, and methacrylate oxetane ester; the second monomer is selected from polypropylene glycol (700) diacrylate, dioxane diol diacrylate, and polyethylene glycol (600) diacrylate; the third monomer is selected from ethoxylated trimethylolpropane triacrylate, ethoxylated pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate; so that the prepared volume holographic optical waveguide device has better comprehensive performance.

Description

Technical Field

[0001] The present invention relates to the field of holographic projection display, and more specifically, to a holographic polymer dispersed liquid crystal material, a volume holographic optical waveguide device and a preparation method thereof. Background Art

[0002] In recent years, Mixed Reality (MR), as a new human-computer interaction technology, has entered the public's field of vision. Mixed Reality combines the advantages of virtual reality and augmented reality, and logically superimposes virtual scenes in real environments. Therefore, it has broad application prospects in various fields such as industrial manufacturing, military, and cultural communication. In practical applications, the optical display system that realizes mixed reality technology is usually composed of a micro display screen and optical devices. Among them, the optical device is mainly based on the optical waveguide solution, specifically, including geometric optical waveguides and diffraction optical waveguides; among them, the diffraction optical waveguide is implemented by "transporting" the virtual image to the human eye and at the same time playing the role of replicating the exit pupil. Specifically, the diffraction optical waveguide consists of a piece of flat glass (i.e., optical waveguide) with very good parallelism and multiple diffraction gratings made on the glass. The diffraction optical waveguide mainly includes a surface relief grating waveguide made by photolithography technology and a volume holographic grating waveguide made based on holographic interference technology.

[0003] Among them, the volume holographic grating used in the volume holographic grating waveguide is formed by irradiating the holographic polymer dispersed liquid crystal material with two beams of coherent light to form interference fringes to modulate the characteristics of the grating material. Holographic polymer dispersed liquid crystal (H-PDLC) material is a combination of holographic technology and polymer dispersed liquid crystal. It is a composite material with a certain orderly arrangement structure system and holographic display function. Due to its excellent electro-optical response characteristics and high refractive index modulation, holographic polymer dispersed liquid crystal materials have shown great application potential in the fields of augmented reality and mixed reality. Specifically, H-PDLC is composed of a periodic arrangement of a polymer-rich phase and a liquid crystal-rich phase. It is formed by polymerization-induced phase separation under coherent lasers. Specifically, a laser beam is divided into two beams of coherent light of equal intensity, and then converged to obtain an interference light field with a sinusoidal distribution of light intensity, and light intensity modulation is generated in the interference area; in the interference bright fringe area (i.e., the coherent bright area), the photoinitiator system absorbs light energy, generates active free radicals, and initiates monomer polymerization. The polymerization reaction causes the chemical potential of the system to change, causing the monomer to diffuse from the coherent dark area to the coherent bright area, and the liquid crystal to diffuse into the coherent dark area, ultimately producing a volume holographic grating composed of alternating polymer-rich phases and liquid crystal-rich phases.

[0004] In practical applications, volume holographic waveguide devices have relatively high requirements for diffraction efficiency and haze. Optical devices with lower haze can produce clear scenes and detailed information during the imaging process, thereby providing a better visual experience. However, although the diffraction efficiency of existing volume holographic grating waveguide devices prepared by holographic polymer dispersed liquid crystal materials can usually meet certain application requirements, their haze is usually high, resulting in poor visual clarity during the imaging process, resulting in a blurred visual effect, which greatly affects the consumer experience. Summary of the invention

[0005] The present invention aims to overcome at least one defect of the above-mentioned prior art and provides a holographic polymer dispersed liquid crystal material, an optical waveguide device and a preparation method thereof, so that the volume holographic optical waveguide device prepared by the holographic polymer dispersed liquid crystal material has both high diffraction efficiency and low haze.

[0006] The technical solution adopted by the present invention is first to provide a holographic polymer dispersed liquid crystal material, which comprises, by mass percentage:

[0007] Solvent: 5%-15%,

[0008] LCD: 30-45%,

[0009] Photoinitiator: 0.1-2%,

[0010] Co-initiator: 0.5-5%,

[0011] First monomer: 5-40%,

[0012] Second monomer: 5-40%,

[0013] The third monomer: 1-10%;

[0014] The first monomer is selected from one or more of lauric acid acrylate, cyclotrimethylolpropane formal acrylate, and methacrylate oxetane;

[0015] The second monomer is selected from one or more of polypropylene glycol (700) diacrylate, hexadecene glycol diacrylate, and polyethylene glycol (600) diacrylate;

[0016] The third monomer is one or more of ethoxylated trimethylolpropane triacrylate, ethoxylated pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate.

[0017] In the present technical solution, by adding the first monomer, the second monomer and the third monomer with different functionalities, the migration efficiency of the monomers and the degree of polymerization reaction between the monomers can be improved by adjusting the ratio of the monomers with different functionalities added, so that the holographic polymer dispersed liquid crystal material is more suitable for exposure processing; at the same time, under the dilution effect of an appropriate amount of solvent, the photoinitiator and the co-initiator are fully dissolved, so that the three unsaturated monomers contained in the material can fully undergo a cross-linking reaction, and at the same time, the monomers can more conveniently and effectively move in space, so that the liquid crystal and the polymer phase are completely separated, thereby forming a regular grating, improving the diffraction efficiency of the prepared volume holographic optical waveguide device, and also reducing the haze of the volume holographic optical waveguide device. That is, in the present technical solution, a holographic polymer dispersed liquid crystal material system with a better refractive index is constructed by adjusting the composition and ratio of the materials, thereby improving the refractive index modulation degree of the volume holographic optical waveguide device prepared by the holographic polymer dispersed liquid crystal material, so that the volume holographic optical waveguide device has better comprehensive performance and service life. Specifically, the first monomer is a monofunctional monomer selected from one or more of lauric acid acrylate, cyclotrimethylolpropane formal acrylate, and methacrylate oxetane; the second monomer is a difunctional monomer selected from one or more of polypropylene glycol (700) diacrylate, dioxane diol diacrylate, and polyethylene glycol (600) diacrylate; the third monomer is a multifunctional monomer, specifically, selected from one or more of ethoxylated trimethylolpropane triacrylate with a trifunctional group, ethoxylated pentaerythritol tetraacrylate with a tetrafunctional group, and dipentaerythritol hexaacrylate with a hexafunctional group; the polymer monomers contained in the holographic polymer dispersed liquid crystal material are diverse in choice, and the raw materials thereof are widely available and easy to obtain, which improves the production convenience and reduces the production cost while ensuring the function of the volume holographic optical waveguide device.

[0018] Furthermore, the photoinitiator is selected from one or more of rose bengal, camphorquinone, hexaarylbiimidazole and carmine.

[0019] Furthermore, the co-initiator is selected from one or more of N,N-dimethylaniline, N,N-diethylaniline and N-phenylglycine.

[0020] Furthermore, the liquid crystal is selected from one or more of E7, E63, P0616A, BL038, and TEB30A.

[0021] Furthermore, the solvent is selected from one or more of dimethyl sulfoxide, hexamethylene diisocyanate, methyl formate, and N-ethylpyrrolidone.

[0022] Another object of the present invention is to provide a method for preparing a volume holographic optical waveguide device, which has a simple process, does not require post-curing, has low production cost and high production efficiency. The preparation method specifically comprises the following steps:

[0023] A liquid crystal cell is prepared in which spacers are uniformly dispersed on a substrate, wherein the dispersion density of the spacers on the substrate of the liquid crystal cell is 50-150 / mm 2 ; and the holographic polymer dispersed liquid crystal material provided in the technical solution is mixed and poured into the liquid crystal box, and after being placed still in a dark room, interference exposure is performed under the interference light field of a double-beam light source.

[0024] In the technical solution, in the method for preparing a volume holographic optical waveguide device, when forming a volume holographic grating, the spacers can be evenly dispersed on the surface of the substrate by dry dispersion or wet dispersion to form a liquid crystal box with spacers evenly dispersed on the substrate. The concentration of the dispersed spacers in the liquid crystal box is likely to affect the haze of the optical waveguide device, thereby affecting the imaging effect of the optical waveguide device. When the concentration of the spacers is small, the number of spacers dispersed on the substrate in the liquid crystal box is small, and the gap is easily flattened during the preparation of the optical waveguide device, and cannot support the spacing of the optical waveguide; when the concentration of the spacers is large, the number of spacers on the glass substrate is large, which will lead to serious light scattering, resulting in a large haze in the optical waveguide device. When preparing the liquid crystal box, by controlling the number of spacers dispersed on the substrate, preferably, the dispersion density of the spacers on the substrate of the liquid crystal box is made to be 50-150 / mm. 2 , which not only ensures that the spacer can stably support the gap of the liquid crystal box, but also reduces light scattering, thereby reducing the haze of the formed volume holographic waveguide device. Therefore, in this technical solution, the comprehensive performance of the formed volume holographic waveguide device can be improved by adjusting the materials and parameters in the production process, making the volume holographic waveguide clearer in imaging, without the need for large-scale equipment, simplifying its preparation process and reducing production costs.

[0025] Optionally, the spacer is selected from silicon spheres, polystyrene microspheres or glass microspheres, and the particle size of the spacer is 3-10 μm.

[0026] Optionally, the thickness of the liquid crystal box is 5-10 μm.

[0027] Optionally, before the interference exposure, the liquid crystal box is placed in a dark room for 1 hour; the interference exposure time is 2-5 minutes, and the irradiation power is 3-6 mW / cm 2 ; and the angle between the dual-beam light sources is 30°-60°.

[0028] The holographic polymer dispersed liquid crystal mixed liquid is filled into a liquid crystal box under vacuum atmosphere and left to stand in a dark room for 1 hour. Another object of the present invention is to provide a volume holographic optical waveguide device prepared by the preparation method provided by the present technical solution.

[0029] Compared with the prior art, the present invention has the following beneficial effects: first, by creatively selecting and combining the first monomer, the second monomer and the third monomer with different functionalities, and adjusting the proportion of the monomers with different functionalities added, a holographic polymer dispersed liquid crystal material system with a better refractive index is constructed, the migration efficiency of the monomers and the degree of polymerization reaction between the monomers are improved, so that the unsaturated monomers in the material can fully undergo cross-linking reaction, and the monomers can more conveniently and effectively move in space, so that the liquid crystal and the polymer phase are completely separated, thereby forming a regular grating, thereby improving the refractive index modulation degree of the volume holographic optical waveguide device prepared by the holographic polymer dispersed liquid crystal material, improving the diffraction efficiency of the prepared volume holographic optical waveguide device, and reducing the haze of the volume holographic optical waveguide device, so that the volume holographic optical waveguide device has better comprehensive performance and service life. At the same time, the polymer monomers contained in the holographic polymer dispersed liquid crystal material are diverse in selection, and the source of the raw materials is wide and easy to obtain, which improves the production convenience and reduces the production cost while ensuring the function of the volume holographic optical waveguide device.

[0030] Secondly, a method for preparing a low-haze volume holographic waveguide device is also provided. By adjusting parameters such as the distribution density of spacers set in the liquid crystal box, the haze of the prepared volume holographic waveguide device is further reduced, making the volume holographic waveguide clearer in imaging, eliminating the need for large-scale equipment, simplifying its preparation process, and reducing production costs. DETAILED DESCRIPTION

[0031] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0032] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0033] The present invention is now further described in conjunction with specific examples. The following examples are only for explaining the present invention, but do not constitute a limitation of the present invention. The test samples and test processes used in the following examples include the following (if the specific experimental conditions are not specified in the examples, they are usually carried out according to conventional conditions or according to the conditions recommended by the reagent company; the reagents, consumables, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels).

[0034] Example 1

[0035] This embodiment provides a holographic polymer dispersed liquid crystal material, a volume holographic optical waveguide device and a preparation method thereof, specifically comprising the following steps:

[0036] (1) Preparation of holographic polymer dispersed liquid crystal materials

[0037] Weigh the raw materials from the brown sample bottle according to the following mass percentages:

[0038] Rose red 0.5%, N, N-dimethylaniline 5%, TEB30A 38%, lauric acid acrylate 16%, methacrylate oxetane 13%, dioxane diol diacrylate 21%, ethoxylated trimethylolpropane triacrylate 3.5%, dimethyl sulfoxide 3%, N-ethylpyrrolidone 5%.

[0039] The weighed raw materials are mixed evenly to obtain a holographic polymer dispersed liquid crystal mixed liquid.

[0040] (2) Preparation of volume holographic optical waveguide devices

[0041] A liquid crystal cell having spacers uniformly dispersed on a substrate is prepared by a dry dispersion method or a wet dispersion method, wherein the dispersion density of the spacers on the substrate of the liquid crystal cell is 100 / mm 2 The prepared liquid crystal box has a thickness of 5 μm; the mixed materials are filled into the liquid crystal box under vacuum conditions and left to stand in a dark room for 1 hour.

[0042] Then, the double beam angle was 40° and the optical power was 5mW / cm 2 A volume holographic optical waveguide device was obtained by exposing using a dual-beam light source for 3 minutes under the conditions.

[0043] (3) Diffraction efficiency test and haze test

[0044] The specific steps of the diffraction efficiency test are as follows: the diffraction efficiency of the volume holographic optical waveguide device is tested by a grating diffraction efficiency tester.

[0045] The specific steps of the haze test are: using a haze meter according to GB 2410-2008 "Test method for light transmittance and haze of transparent plastics" to test the haze of the above-mentioned volume holographic optical waveguide device at 23±2°C.

[0046] Example 2

[0047] This embodiment provides a holographic polymer dispersed liquid crystal material, a volume holographic optical waveguide device and a preparation method thereof, specifically comprising the following steps:

[0048] (1) Preparation of holographic polymer dispersed liquid crystal materials

[0049] Weigh the raw materials from the brown sample bottle according to the following mass percentages:

[0050] Camphorquinone 1%, N,N-dimethylaniline 2.5%, BL038 35%, cyclotrimethylolpropane formal acrylate 18%, methacrylate oxetane 12%, polypropylene glycol (700) diacrylate 19%, ethoxylated pentaerythritol tetraacrylate 2.5%, hexamethylene diisocyanate 4%, N-ethylpyrrolidone 6%.

[0051] The weighed raw materials are mixed evenly to obtain a holographic polymer dispersed liquid crystal mixed liquid.

[0052] (2) Preparation of volume holographic optical waveguide devices

[0053] A liquid crystal cell having spacers uniformly dispersed on a substrate is prepared by a dry dispersion method or a wet dispersion method, wherein the dispersion density of the spacers on the substrate of the liquid crystal cell is 80 / mm 2 The prepared liquid crystal box has a thickness of 5 μm; the mixed materials are filled into the liquid crystal box under vacuum conditions and allowed to stand in a dark room for 1 hour.

[0054] Then, the double beam angle was 40° and the optical power was 5mW / cm 2 A volume holographic optical waveguide device was obtained by exposing using a dual-beam light source for 3 minutes under the conditions.

[0055] (3) Diffraction efficiency test and haze test

[0056] The specific steps of the diffraction efficiency test are as follows: the diffraction efficiency of the volume holographic optical waveguide device is tested by a grating diffraction efficiency tester.

[0057] The specific steps of the haze test are: using a haze meter according to GB 2410-2008 "Test method for light transmittance and haze of transparent plastics" to test the haze of the above-mentioned volume holographic optical waveguide device at 23±2°C.

[0058] Example 3

[0059] This embodiment provides a holographic polymer dispersed liquid crystal material, a volume holographic optical waveguide device and a preparation method thereof, specifically comprising the following steps:

[0060] (1) Preparation of holographic polymer dispersed liquid crystal materials

[0061] Weigh the raw materials from the brown sample bottle according to the following mass percentages:

[0062] Magenta 1.5%, N-phenylglycine 3%, E63 36%, cyclotrimethylolpropane formal acrylate 14%, lauric acid acrylate 12%, polyethylene glycol (600) diacrylate 24%, official dipentaerythritol hexaacrylate 1.5%, N-ethylpyrrolidone 8%.

[0063] The weighed raw materials are mixed evenly to obtain a holographic polymer dispersed liquid crystal mixed liquid.

[0064] (2) Preparation of volume holographic optical waveguide devices

[0065] A liquid crystal cell having spacers uniformly dispersed on a substrate is prepared by a dry dispersion method or a wet dispersion method, wherein the dispersion density of the spacers on the substrate of the liquid crystal cell is 120 / mm 2 The prepared liquid crystal box has a thickness of 5 μm; the mixed materials are filled into the liquid crystal box under vacuum conditions and allowed to stand in a dark room for 1 hour.

[0066] Then, the double beam angle was 40° and the optical power was 5mW / cm 2 A volume holographic optical waveguide device was obtained by exposing using a dual-beam light source for 3 minutes under the conditions.

[0067] (3) Diffraction efficiency test and haze test

[0068] The specific steps of the diffraction efficiency test are as follows: the diffraction efficiency of the volume holographic optical waveguide device is tested by a grating diffraction efficiency tester.

[0069] The specific steps of the haze test are: using a haze meter according to GB 2410-2008 "Test method for light transmittance and haze of transparent plastics" to test the haze of the above-mentioned volume holographic optical waveguide device at 23±2°C.

[0070] Example 4

[0071] This embodiment provides a holographic polymer dispersed liquid crystal material, a volume holographic optical waveguide device and a preparation method thereof, specifically comprising the following steps:

[0072] (1) Preparation of holographic polymer dispersed liquid crystal materials

[0073] Weigh the raw materials from the brown sample bottle according to the following mass percentages:

[0074] Rose Red 1%, N, N-diethylaniline 6%, E63 38%, lauric acid acrylate 10%, methacrylate oxetane 10%, cyclotrimethylolpropane formal acrylate 12%, dioxanediol diacrylate 15%, ethoxylated trimethylolpropane triacrylate 3%, N-ethylpyrrolidone 5%.

[0075] The weighed raw materials are mixed evenly to obtain a holographic polymer dispersed liquid crystal mixed liquid.

[0076] (2) Preparation of volume holographic optical waveguide devices

[0077] A liquid crystal cell having spacers uniformly dispersed on a substrate is prepared by a dry dispersion method or a wet dispersion method, wherein the dispersion density of the spacers on the substrate of the liquid crystal cell is 50 / mm 2 The prepared liquid crystal box has a thickness of 5 μm; the mixed materials are filled into the liquid crystal box under vacuum conditions and allowed to stand in a dark room for 1 hour.

[0078] Then, the double beam angle was 40° and the optical power was 5mW / cm 2 A volume holographic optical waveguide device was obtained by exposing using a dual-beam light source for 3 minutes under the conditions.

[0079] (3) Diffraction efficiency test and haze test

[0080] The specific steps of the diffraction efficiency test are as follows: the diffraction efficiency of the volume holographic optical waveguide device is tested by a grating diffraction efficiency tester.

[0081] The specific steps of the haze test are: using a haze meter according to GB 2410-2008 "Test method for light transmittance and haze of transparent plastics" to test the haze of the above-mentioned volume holographic optical waveguide device at 23±2°C.

[0082] Example 5

[0083] This embodiment provides a holographic polymer dispersed liquid crystal material, a volume holographic optical waveguide device and a preparation method thereof, specifically comprising the following steps:

[0084] (1) Preparation of holographic polymer dispersed liquid crystal materials

[0085] Weigh the raw materials from the brown sample bottle according to the following mass percentages:

[0086] Rose Bengal 2%, N,N-dimethylaniline 3%, E7 34%, lauric acid acrylate 27%, polypropylene glycol (700) diacrylate 24%, dipentaerythritol hexaacrylate 3%, hexamethylene diisocyanate 2%, N-ethylpyrrolidone 5%.

[0087] The weighed raw materials are mixed evenly to obtain a holographic polymer dispersed liquid crystal mixed liquid.

[0088] (2) Preparation of volume holographic optical waveguide devices

[0089] A liquid crystal cell having spacers uniformly dispersed on a substrate is prepared by a dry dispersion method or a wet dispersion method, wherein the dispersion density of the spacers on the substrate of the liquid crystal cell is 150 / mm 2 The prepared liquid crystal box has a thickness of 5 μm; the mixed materials are filled into the liquid crystal box under vacuum conditions and allowed to stand in a dark room for 1 hour.

[0090] Then, the double beam angle was 40° and the optical power was 5mW / cm 2 A volume holographic optical waveguide device was obtained by exposing using a dual-beam light source for 3 minutes under the conditions.

[0091] (3) Diffraction efficiency test and haze test

[0092] The specific steps of the diffraction efficiency test are as follows: the diffraction efficiency of the volume holographic optical waveguide device is tested by a grating diffraction efficiency tester.

[0093] The specific steps of the haze test are: using a haze meter according to GB 2410-2008 "Test method for light transmittance and haze of transparent plastics" to test the haze of the above-mentioned volume holographic optical waveguide device at 23±2°C.

[0094] Comparative Example 1

[0095] This comparative example provides a holographic polymer dispersed liquid crystal material, a volume holographic optical waveguide device and a preparation method thereof, specifically comprising the following steps:

[0096] (1) Preparation of holographic polymer dispersed liquid crystal materials

[0097] Weigh the raw materials from the brown sample bottle according to the following mass percentages:

[0098] Rose red 0.5%, N, N-dimethylaniline 5%, TEB30A 36%, lauric acid acrylate 16%, methacrylate oxetane 18%, dioxanediol diacrylate 21%, ethoxylated trimethylolpropane triacrylate 3.5%.

[0099] The weighed raw materials are mixed evenly to obtain a holographic polymer dispersed liquid crystal mixed liquid.

[0100] (2) Preparation of volume holographic optical waveguide devices

[0101] A liquid crystal cell having spacers uniformly dispersed on a substrate is prepared by a dry dispersion method or a wet dispersion method, wherein the dispersion density of the spacers on the substrate of the liquid crystal cell is 60 / mm 2 The prepared liquid crystal box has a thickness of 5 μm; the mixed materials are filled into the liquid crystal box under vacuum conditions and allowed to stand in a dark room for 1 hour.

[0102] Then, the double beam angle was 40° and the optical power was 5mW / cm 2 A volume holographic optical waveguide device was obtained by exposing using a dual-beam light source for 3 minutes under the conditions.

[0103] (3) Diffraction efficiency test and haze test

[0104] The specific steps of the diffraction efficiency test are as follows: the diffraction efficiency of the volume holographic optical waveguide device is tested by a grating diffraction efficiency tester.

[0105] The specific steps of the haze test are: using a haze meter according to GB 2410-2008 "Test method for light transmittance and haze of transparent plastics" to test the haze of the above-mentioned volume holographic optical waveguide device at 23±2°C.

[0106] Comparative Example 2

[0107] This comparative example provides a holographic polymer dispersed liquid crystal material, a volume holographic optical waveguide device and a preparation method thereof, specifically comprising the following steps:

[0108] (1) Preparation of holographic polymer dispersed liquid crystal materials

[0109] Weigh the raw materials from the brown sample bottle according to the following mass percentages:

[0110] Camphorquinone 1%, N,N-dimethylaniline 5%, BL038 38%, polypropylene glycol (700) diacrylate 16%, hexadecene glycol diacrylate 15%, ethoxylated pentaerythritol tetraacrylate 15%, hexamethylene diisocyanate 4%, N-ethylpyrrolidone 6%.

[0111] The weighed raw materials are mixed evenly to obtain a holographic polymer dispersed liquid crystal mixed liquid.

[0112] (2) Preparation of volume holographic optical waveguide devices

[0113] A liquid crystal cell having spacers uniformly dispersed on a substrate is prepared by a dry dispersion method or a wet dispersion method, wherein the dispersion density of the spacers on the substrate of the liquid crystal cell is 100 / mm 2 The prepared liquid crystal box has a thickness of 5 μm; the mixed materials are filled into the liquid crystal box under vacuum conditions and allowed to stand in a dark room for 1 hour.

[0114] Then, the double beam angle was 40° and the optical power was 5mW / cm 2 A volume holographic optical waveguide device was obtained by exposing using a dual-beam light source for 3 minutes under the conditions.

[0115] (3) Diffraction efficiency test and haze test

[0116] The specific steps of the diffraction efficiency test are as follows: the diffraction efficiency of the volume holographic optical waveguide device is tested by a grating diffraction efficiency tester.

[0117] The specific steps of the haze test are: using a haze meter according to GB 2410-2008 "Test method for light transmittance and haze of transparent plastics" to test the haze of the above-mentioned volume holographic optical waveguide device at 23±2°C.

[0118] Comparative Example 3

[0119] This comparative example provides a low-haze holographic polymer dispersed liquid crystal material, a volume holographic optical waveguide device and a preparation method thereof, specifically comprising the following steps:

[0120] (1) Preparation of holographic polymer dispersed liquid crystal materials

[0121] Weigh the raw materials from the brown sample bottle according to the following mass percentages:

[0122] Magenta 1%, N-phenylglycine 4%, E63 40%, polyethylene glycol (600) diacrylate 34%, dipentaerythritol hexaacrylate 4%, ethoxylated trimethylolpropane triacrylate 15%.

[0123] The weighed raw materials are mixed evenly to obtain a holographic polymer dispersed liquid crystal mixed liquid.

[0124] (2) Preparation of volume holographic optical waveguide devices

[0125] A liquid crystal cell having spacers uniformly dispersed on a substrate is prepared by a dry dispersion method or a wet dispersion method, wherein the dispersion density of the spacers on the substrate of the liquid crystal cell is 80 / mm 2 The prepared liquid crystal box has a thickness of 5 μm; the mixed materials are filled into the liquid crystal box under vacuum conditions and allowed to stand in a dark room for 1 hour.

[0126] Then, the double beam angle was 40° and the optical power was 5mW / cm 2 A volume holographic optical waveguide device was obtained by exposing using a dual-beam light source for 3 minutes under the conditions.

[0127] (3) Diffraction efficiency test and haze test

[0128] The specific steps of the diffraction efficiency test are as follows: the diffraction efficiency of the volume holographic optical waveguide device is tested by a grating diffraction efficiency tester.

[0129] Comparative Example 4

[0130] This comparative example provides a low-haze holographic polymer dispersed liquid crystal material, a volume holographic optical waveguide device and a preparation method thereof, specifically comprising the following steps:

[0131] (1) Preparation of holographic polymer dispersed liquid crystal materials

[0132] Weigh the raw materials from the brown sample bottle according to the following mass percentages:

[0133] Rose Red 1%, N, N-diethylaniline 6%, E63 38%, lauric acid acrylate 10%, methacrylate oxetane 12%, cyclotrimethylolpropane formal acrylate 15%, dioxanediol diacrylate 15%, ethoxylated trimethylolpropane triacrylate 3%.

[0134] The weighed raw materials are mixed evenly to obtain a holographic polymer dispersed liquid crystal mixed liquid.

[0135] (2) Preparation of volume holographic optical waveguide devices

[0136] A liquid crystal cell having spacers uniformly dispersed on a substrate is prepared by a dry dispersion method or a wet dispersion method, wherein the dispersion density of the spacers on the substrate of the liquid crystal cell is 90 / mm 2 The prepared liquid crystal box has a thickness of 5 μm; the mixed materials are filled into the liquid crystal box under vacuum conditions and allowed to stand in a dark room for 1 hour.

[0137] Then, the double beam angle was 40° and the optical power was 5mW / cm 2 A volume holographic optical waveguide device was obtained by exposing using a dual-beam light source for 3 minutes under the conditions.

[0138] (3) Diffraction efficiency test and haze test

[0139] The specific steps of the diffraction efficiency test are as follows: the diffraction efficiency of the volume holographic optical waveguide device is tested by a grating diffraction efficiency tester.

[0140] The specific steps of the haze test are: using a haze meter according to GB 2410-2008 "Test method for light transmittance and haze of transparent plastics" to test the haze of the above-mentioned volume holographic optical waveguide device at 23±2°C.

[0141] In Examples 1 to 5, in the method for preparing a volume holographic waveguide device, the material for forming the volume holographic waveguide device is selected and combined from the first monomer, the second monomer and the third monomer provided in the technical solution, wherein the first monomer is a monofunctional monomer selected from one or more of lauric acid acrylate, cyclotrimethylolpropane formal acrylate and methacrylate oxetane ester; the second monomer is a difunctional monomer selected from one or more of polypropylene glycol (700) diacrylate, dioxane diol diacrylate and polyethylene glycol (600) diacrylate; the third monomer is a multifunctional monomer, specifically, selected from one or more of ethoxylated trimethylolpropane triacrylate having a trifunctional group, ethoxylated pentaerythritol tetraacrylate having a tetrafunctional group, and dipentaerythritol hexaacrylate having a hexafunctional group; when preparing a liquid crystal cell, the dispersion density of the spacers on the substrate of the liquid crystal cell is 50-150 pcs / mm 2 , and then a volume holographic optical waveguide device with high diffraction efficiency and low haze is formed. In the comparative example, in the preparation method of the holographic optical waveguide device, it is set that the composition, proportion or preparation parameters of the selected holographic polymer dispersed liquid crystal material are not completely consistent with those selected in the present technical solution. Specifically, in comparative example 1, it is set that the selected holographic polymer dispersed liquid crystal material does not contain the first monomer and solvent provided in the present technical solution; in comparative example 2, it is set that in the selected holographic polymer dispersed liquid crystal material, at least one type of polymer monomer in the selected first monomer, second monomer or third monomer is selected from other monomers that do not belong to the selection range of the first monomer, second monomer and third monomer provided in the present technical solution; in comparative example 3, it is set that when preparing the liquid crystal box, the dispersion density of the spacer on the substrate of the liquid crystal box is not within the parameter selection range provided in the present technical solution; in comparative example 4, it is set that the selected holographic polymer dispersed liquid crystal material does not contain the solvent provided in the present technical solution.

[0142] The diffraction efficiency and haze test results of the eight holographic polymer dispersed liquid crystal materials and the volume holographic optical waveguide devices prepared therefrom in Examples 1 to 4 and Comparative Examples 1 to 4 are shown in the following table:

[0143]

[0144] By comparing the embodiments and the comparative examples, it can be found that the test results of the diffraction efficiency and haze of the obtained holographic optical waveguide device show that: according to the preparation method of the holographic optical waveguide device provided by the present technical solution, when the composition, proportion and preparation parameters of the holographic polymer dispersed liquid crystal material selected for preparing the holographic optical waveguide device are selected and combined in accordance with the present technical solution, the prepared volume holographic optical waveguide device has both higher diffraction efficiency and lower haze, indicating that the prepared volume holographic optical waveguide device has better comprehensive performance, will produce clearer scene and detail information during the imaging process, thereby providing a better visual experience, and is more suitable for application as a high-precision mixed reality optical device.

[0145] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the technical solution of the present invention, and are not intended to limit the specific implementation methods of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the claims of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A holographic polymer dispersed liquid crystal material, characterized in that: In terms of mass percentage, it includes: Solvent: 5%-15%, LCD: 30-45%, Photoinitiator: 0.1-2%, Co-initiator: 0.5-5%, First monomer: 5-40%, Second monomer: 5-40%, The third monomer: 1-10%; The first monomer is selected from one or more of lauric acid acrylate, cyclotrimethylolpropane formal acrylate, and methacrylate oxetane; The second monomer is selected from one or more of polypropylene glycol (700) diacrylate, hexadecene glycol diacrylate, and polyethylene glycol (600) diacrylate; The third monomer is one or more of ethoxylated trimethylolpropane triacrylate, ethoxylated pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate.

2. The holographic polymer dispersed liquid crystal material according to claim 1, characterized in that: The photoinitiator is selected from one or more of rose bengal, camphorquinone, hexaarylbiimidazole and carmine.

3. The holographic polymer dispersed liquid crystal material according to claim 1, characterized in that: The co-initiator is selected from one or more of N,N dimethylaniline, N,N diethylaniline and N-phenylglycine.

4. The holographic polymer dispersed liquid crystal material according to claim 1, characterized in that: The liquid crystal is selected from one or more of E7, E63, P0616A, BL038, and TEB30A.

5. The holographic polymer dispersed liquid crystal material according to claim 1, characterized in that: The solvent is selected from one or more of dimethyl sulfoxide, hexamethylene diisocyanate, methyl formate, and N-ethylpyrrolidone.

6. A method for preparing a volume holographic optical waveguide device, characterized in that: The following steps are involved: A liquid crystal cell is prepared in which spacers are uniformly dispersed on a substrate, wherein the dispersion density of the spacers on the substrate of the liquid crystal cell is 50-150 / mm 2 ; The holographic polymer dispersed liquid crystal material according to any one of claims 1 to 5 is mixed and poured into the liquid crystal box, and after being placed still in a dark room, interference exposure is performed under the interference light field of a double-beam light source.

7. The preparation method according to claim 6, characterized in that: The spacer is selected from SiO2 microspheres, polystyrene microspheres or metal microspheres, and the particle size of the spacer is 3-10 μm.

8. The preparation method according to claim 6, characterized in that: The thickness of the liquid crystal cell is 5-10 μm.

9. The preparation method according to claim 6, characterized in that: Before the interference exposure, the liquid crystal box was placed in a dark room for 1 hour; the interference exposure time was 2-5 minutes, and the irradiation power was 3-6 mW / cm 2 ; and the angle between the dual-beam light sources is 30°-60°.

10. A volume holographic optical waveguide device, characterized in that: Prepared by the preparation method according to any one of claims 6 to 9.

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