Holographic photopolymer material, holographic optical element, and optical device

Abstract

The present application relates to the field of holographic technology and provides a holographic photopolymer material, a holographic optical element, and an optical device. The raw materials of the holographic photopolymer material include a matrix polymer and a photopolymerizable monomer, and the photopolymerizable monomer includes a first olefin monomer and a second olefin monomer that can form a photopolymer through a photopolymerization reaction, wherein the structure of the first olefin monomer is shown in formula (1), and the structure of the second olefin monomer is shown in formula (2). #imgabs0# In formula (1), at least one of R1 and R2 contains a hydroxyl group and / or an amino group; in formula (2), R3 and R4 are each independently selected from a hydrogen atom or an atomic group, and R3 and R4 are not hydrogen atoms at the same time; the refractive index of the photopolymer is higher than the refractive index of the matrix polymer. The holographic optical element made of the holographic photopolymer material provided in the present application has a diffraction efficiency greater than 80%, and a light transmittance greater than 80% in the visible light band (400-800nm).

Description

Technical Field

[0001] The present application belongs to the field of holographic technology, and in particular relates to a holographic photopolymer material, a holographic optical element, and an optical device. Background Art

[0002] Holographic technology can simultaneously store all information such as the phase and amplitude of light, and has been widely used in holographic optical elements, data storage, high-end anti-counterfeiting, 3D displays, sensors and other fields. Holographic recording refers to the process of recording all information such as the amplitude and phase of coherent light through photopolymerization under the irradiation of coherent excitation light. Holographic recording materials are the key to supporting the application and development of holographic technology. Among them, holographic photopolymer materials refer to polymer materials that can record holographic information. They have the advantages of a wide photosensitivity range, good storage stability, and convenient transportation and use. They have become a holographic recording material that has attracted much attention. Reflective holographic gratings are an important holographic optical element. They are prepared by dividing a beam of excitation light into two beams of coherent light, and incident and coherently coherently from different surfaces of the holographic recording material. Making holographic photopolymer materials into reflective holographic gratings is an effective way to verify the performance of holographic photopolymer materials, and it is also a way to use holographic photopolymers. Holographic photopolymer materials are composed of matrix polymers, photopolymerizable monomers and photoinitiator systems, wherein the photoinitiator system is used to absorb photons and generate active centers (such as free radicals) to initiate monomer polymerization. The method of making a holographic photopolymer material into a reflective holographic grating mainly includes the following steps: first, the components are dissolved evenly and coated into a film; then, holographic recording is performed under coherent light irradiation, and the photopolymerizable monomers in the coherent bright area are polymerized to generate photopolymers, and some monomers in the coherent dark area diffuse into the coherent bright area to participate in the polymerization reaction, and the basic grating structure is formed through phase separation. The refractive index of the photopolymer is generally higher than that of the matrix polymer, which increases the refractive index difference between the coherent bright area and the coherent dark area, and improves the grating diffraction efficiency; finally, after post-treatment such as ultraviolet light irradiation and heating, the photopolymerizable monomers in the system are completely consumed, and the system is further phase-separated to obtain a holographic grating with higher diffraction efficiency. The recording principle of holographic photopolymer materials is as follows: Figure 1 shown.

[0003] Reflective holographic gratings made from holographic photopolymer materials with excellent performance should have high diffraction efficiency at the Bragg wavelength and high transmittance at non-Bragg wavelengths. Industry researchers have provided a method for forming a reflective holographic grating, in which two coherent light beams enter a recording medium from opposite sides and generate an interference pattern therein, thereby forming a holographic grating. The medium is a substantially solid, photopolymerizable layer that essentially comprises: (a) a polymer binder selected from the group consisting of polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl formal, copolymers containing their main chain segments, and mixtures thereof; (b) an ethylenically unsaturated monomer selected from the group consisting of a carbazole-containing monomer and a liquid monomer containing one or more phenyl groups, a phenoxy group, a naphthyl group, a naphthyloxy group, an aromatic heterocycle containing up to three aromatic rings, chlorine, and bromine; and (c) a photoinitiator system that can be activated by light irradiation. This method achieves high diffraction efficiency at the Bragg wavelength. Besides diffraction efficiency, transmittance is also a key parameter for reflective holographic gratings. The aforementioned techniques modulate the diffraction efficiency of the grating by varying the binder and monomers, but ignore the photoreaction and phase separation behavior of the monomers. Consequently, it is not possible to produce reflective holographic gratings with both high diffraction efficiency (>80%) and high transmittance (>80% in the 400-800nm ​​range). Summary of the Invention

[0004] The purpose of this application is to provide a holographic photopolymer material, aiming to solve the problem that the existing holographic photopolymer material cannot achieve both high diffraction efficiency (>80%) and high transmittance (greater than 80% in the range of 400-800nm) when forming holographic optical elements such as reflective holographic gratings.

[0005] To achieve the above application objectives, the technical solutions adopted in this application are as follows:

[0006] In a first aspect, the present application provides a holographic photopolymer material. The raw materials of the holographic photopolymer material include a matrix polymer and a photopolymerizable monomer. The photopolymerizable monomer includes a first olefin monomer and a second olefin monomer that can be photopolymerized to form a photopolymer. The structure of the first olefin monomer is shown in formula (1), and the structure of the second olefin monomer is shown in formula (2).

[0007]

[0008] In formula (1), at least one of R1 and R2 contains a hydroxyl group and / or an amino group;

[0009] In formula (2), R3 and R4 are each independently selected from a hydrogen atom or an atomic group, and R3 and R4 are not both hydrogen atoms;

[0010] The refractive index of the photopolymer is higher than the refractive index of the matrix polymer.

[0011] The holographic photopolymer material provided by the present application comprises a first olefin monomer and a second olefin monomer as shown in formula (1) and formula (2) respectively. During the interference process of the excitation light, the first olefin monomer and the second olefin monomer are photopolymerized to form a photopolymer, and form partitions with the matrix polymer having a refractive index difference, thereby achieving phase separation and improving the diffraction efficiency of the holographic photopolymer material. At the same time, since the first olefin monomer contains at least one of a hydroxyl group and an amino group, during the phase separation process, the photopolymer forms hydrogen bonds with the matrix polymer through the hydroxyl group and the amino group, thereby reducing the risk of local agglomeration of the holographic photopolymer material and reducing the probability of the photopolymer or the matrix polymer agglomerating to form large particles, thereby effectively improving the transparency of the holographic photopolymer material. The holographic photopolymer material provided by the present application can be used to produce a holographic optical element with a diffraction efficiency greater than 80% and a light transmittance greater than 80% in the visible light band (400-800nm).

[0012] As a possible implementation method, in the photopolymerizable monomer, the ratio of the total molar amount of the hydroxyl group and the amino group to the molar amount of the olefin functional group is 0.05:1 to 0.6:1. In this case, the photopolymer formed by the first olefin monomer and the second olefin monomer is distributed with a suitable content of hydroxyl groups and amino groups, which is beneficial to enhance the hydrogen bonding between the photopolymer and the matrix polymer, thereby effectively reducing the risk of agglomeration between the photopolymers and between the matrix polymers in the holographic photopolymer material, and thus improving the transparency of the photopolymer and the matrix polymer. The present application optimizes the phase separation structure of the photopolymer formed by the photopolymerization reaction and the matrix polymer by regulating the molar ratio of the polar groups of the photopolymerizable monomers, thereby effectively adjusting the contradiction between the transmittance and the diffraction efficiency of the holographic photopolymer material, and obtaining a holographic photopolymer material with both excellent refractive efficiency and transmittance.

[0013] As a possible implementation, in the first olefin monomer, the R1 is selected from a hydrogen atom or a methyl group, and the R2 is selected from a hydroxyl group, an amino group, -O(CH2) n OH, -O(CH2) n NH2, wherein n is an integer from 1 to 6. In this case, the first olefin monomer formed, and the photopolymer produced by copolymerization of the first olefin monomer with the second olefin monomer, contain hydroxyl groups and / or amino groups capable of generating hydrogen bonds with the matrix polymer, thereby inhibiting aggregation of the photopolymer caused by phase separation, reducing light scattering, and improving the transmittance of the holographic photopolymer material and the optical component produced therefrom, such as a grating.

[0014] As a possible implementation method, the first olefin monomer is selected from at least one of the following structures:

[0015]

[0016] The first olefin monomer contains hydroxyl or amino groups. After polymerization with the second olefin monomer to form a photopolymer, the hydroxyl or amino groups carried by the first olefin monomer are dispersed in the photopolymer. Through the hydroxyl or amino groups in the photopolymer, the photopolymer and the matrix polymer are hydrogen-bonded, reducing the risk of aggregation and ultimately improving the transparency of the material. The resulting holographic photopolymer material has both excellent diffraction efficiency and transparency.

[0017] As a possible implementation of the present application, the refractive index of the second olefin monomer is greater than 1.5. In this case, the photopolymer formed by the photopolymerization reaction of the first olefin monomer and the second olefin monomer has a higher refractive index, and the refractive index difference between the first olefin monomer and the second olefin monomer increases, which is conducive to improving the diffraction efficiency of the holographic photopolymer material.

[0018] As a possible implementation of the present application, R3 is selected from a hydrogen atom, a methyl group, or an aromatic group, and R4 is selected from a phenylethyl group, an o-phenylphenoxyethyl group, a 4-(1-methyl-1-phenylethyl)phenoxyethyl group, a 2,4,6-tribromophenyl group, a 2,4,6-tribromophenoxyethyl group, a pentabromophenyl group, a pentabromobenzyl group, a pentabromophenoxyethyl group, a 1-naphthyl group, a 2-naphthyl group, a 2-naphthyloxyethyl group, a 9-anthrylmethyl group, a 9H-carbazole-9-ethyl group, a bisphenol A dimethyl group, an ethoxylated bisphenol A dimethyl group, or a bisphenol A glycerol dimethyl group. The second olefin monomer formed by the above groups contains an aromatic group, which is beneficial for increasing the refractive index of the monomer, thereby increasing the refractive index difference between the photopolymer and the matrix polymer, and improving the diffraction efficiency of the holographic photopolymer material.

[0019] As a possible implementation of the present application, the second olefin monomer is selected from at least one of the following structures:

[0020]

[0021]

[0022] The photopolymer formed by photopolymerization of the second olefin monomer with the first olefin monomer exhibits enhanced phase separation, facilitating an increase in the refractive index difference between coherent bright and dark regions. Furthermore, hydrogen bonding provided by the hydroxyl and / or amino groups of the first olefin monomer inhibits aggregation between the polymers and regulates the phase-separated microdomains of the photopolymer, preventing excessive microdomain size from causing light scattering and, consequently, reducing the impact on the material's transmittance. This achieves a comprehensive improvement in the diffraction efficiency and transmittance of the holographic photopolymer material. Specifically, the first olefin monomer reduces the material's transmittance by physically crosslinking the photopolymer with the matrix polymer through the hydroxyl and / or amino groups on the first olefin monomer, reducing aggregation between the two, thereby effectively improving the transmittance of the holographic photopolymer material and ultimately endowing the holographic photopolymer with excellent diffraction efficiency and transmittance.

[0023] As a possible implementation of the present application, the molar ratio of the first olefin monomer to the second olefin monomer is 0.05:1 to 1.5:1. Since the hydroxyl and amino groups in the photopolymer formed by the first olefin monomer and the second olefin monomer are mainly derived from the first olefin monomer. Therefore, when the first olefin monomer and the second olefin monomer participate in the photopolymerization reaction in the above-mentioned molar ratio, the content of hydroxyl and amino groups in the obtained photopolymer can be effectively regulated, thereby facilitating the enhancement of hydrogen bonding between the photopolymer and the matrix polymer, reducing the risk of agglomeration between the photopolymers and the matrix polymers in the holographic photopolymer material, and thereby improving the transparency of the holographic photopolymer material.

[0024] As a possible implementation of the present application, the matrix polymer is selected from at least one of polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl formal, and polymethyl methacrylate. On one hand, the matrix polymer has a relatively low refractive index, which facilitates a large refractive index difference between the photopolymer formed with the first olefin monomer and the second olefin monomer, thereby improving the diffraction efficiency of the holographic photopolymer material. On the other hand, the first olefin monomer contains hydroxyl or amino groups, and the matrix polymer contains abundant binding sites. Therefore, the hydroxyl or amino groups in the photopolymer can form hydrogen bonds with the matrix polymer through these binding sites, thereby improving the light transmittance of both.

[0025] As a possible implementation of this application, based on 100 parts by weight of the matrix polymer and the photopolymerizable monomer, the matrix polymer comprises 20 to 80 parts by weight, and the photopolymerizable monomer comprises 20 to 80 parts by weight. In this case, the content of the photopolymer formed by photopolymerization of the photopolymerizable monomer and the matrix polymer is controlled within a reasonable range, which can improve the film-forming properties of the holographic photopolymer material, facilitate flexible processing of the material, such as roll-to-roll coating, and optimize diffraction efficiency and transmittance.

[0026] As a possible implementation of the present application, the raw materials of the holographic photopolymer material also include a photosensitizer and a co-initiator. Under light conditions, the photosensitizer is activated, and under the synergistic action of the co-initiator, the first olefin monomer and the second olefin monomer are induced to undergo a photopolymerization reaction to form a photopolymer, thereby obtaining a holographic photopolymer material.

[0027] As a possible implementation of the present application, the holographic photopolymer material is composed of the matrix polymer and the photopolymer. In this case, the optical element formed by the holographic photopolymer material is partitioned by the matrix polymer and the photopolymer to generate a basic grating structure.

[0028] As a possible implementation of this application, the photopolymer is produced by photopolymerizing the first olefin monomer and the second olefin monomer. In this case, the two monomers can not only endow the photopolymer with a rich content of hydroxyl or amino groups, providing sites for the photopolymer to bind to the matrix polymer, but also increase the refractive index of the photopolymer, widening the refractive index difference between the photopolymer and the matrix polymer, thereby improving the performance of the holographic photopolymer material.

[0029] As a possible implementation of this application, the wavelength of the excitation light for photopolymerization is 400nm to 800nm. This range of excitation light is a wavelength band commonly used in holographic recording scenarios. By selecting a photoinitiator system sensitive to excitation light in this wavelength band, photopolymerization between the first olefin monomer and the second olefin monomer can be effectively stimulated, expanding application scenarios.

[0030] As a possible implementation of the present application, during the photopolymerization process, the light intensity is 0.5 to 3 mW / cm 2 Exposure treatment at this light intensity can effectively activate the photosensitizer in the photoinitiator system, promote the photopolymerization reaction between the first olefin monomer and the second olefin monomer, and improve the production efficiency of the photopolymer.

[0031] As a possible implementation of the present application, in the holographic photopolymer material, the hydroxyl group and the amino group account for 1×10 of the total mass of the holographic photopolymer material. -4 ~5×10 -3 By increasing and regulating the hydroxyl and amino group contents in the holographic photopolymer material, the amount of hydrogen bonding between the photopolymer and the matrix polymer can be controlled, effectively controlling the agglomeration between the photopolymers and the matrix polymers in the holographic photopolymer material, thereby improving the transparency of the photopolymer and the matrix polymer.

[0032] A second aspect of the present application provides a holographic optical element, comprising the holographic photopolymer material described in the first aspect of the present application.

[0033] A third aspect of the present application provides an optical device, comprising the holographic optical element described in the second aspect of the present application.

[0034] Due to the inclusion of the aforementioned holographic photopolymer material, the holographic optical element provided herein exhibits both excellent diffraction and light transmission properties. Specifically, the holographic optical element exhibits a diffraction efficiency exceeding 80% and a light transmittance exceeding 80% in the visible light band (400-800 nm). Similarly, the optical device provided herein, due to its inclusion of the aforementioned holographic optical element, can also improve both the diffraction and light transmission properties of the optical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the recording principle of holographic photopolymer materials provided by the prior art;

[0036] Figure 2 is a schematic diagram of preparing a holographic photosensitive film provided in an embodiment of the present application;

[0037] Figure 3A Schematic diagram of holographic recording using a dual-beam interferometry method according to an embodiment of the present application;

[0038] Figure 3B Schematic diagram of holographic recording using a single-beam interferometry method according to an embodiment of the present application;

[0039] Figure 4 is a schematic diagram of the transmittance curve of the reflective holographic grating provided in Example 1 of the present application;

[0040] Figure 5 This is a transmittance curve of the reflective holographic grating prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0041] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0042] In this application, the term "and / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0043] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0044] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0045] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0046] The weights of the relevant components mentioned in the examples of this application may not only refer to the specific content of each component, but also represent the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the examples of this application, it is within the scope disclosed in the examples of this application. Specifically, the mass described in the examples of this application may be a well-known mass unit such as μg, mg, or g.

[0047] The terms "first" and "second" are used solely for descriptive purposes to distinguish objects, such as substances, from one another and should not be understood to indicate or imply relative importance or to implicitly specify the quantity of the technical features being referred to. For example, without departing from the scope of the embodiments of this application, a first XX may also be referred to as a second XX, and similarly, a second XX may also be referred to as a first XX. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of such features.

[0048] The term "CAS" stands for "Chemical Abstracts Service," meaning that the Chemical Abstracts Service (CAS), a subsidiary of the American Chemical Society, assigns a CAS number to each substance appearing in the literature. This is to avoid the inconvenience of having multiple chemical names and to facilitate database searches. In biochemistry, the abbreviation CAS has become synonymous with a unique identification code for substances, essentially giving each chemical substance its own "student number."

[0049] The term "PET" stands for "Polyethylene Eerephthalate," meaning polyethylene terephthalate. PET film is a well-rounded packaging film with excellent mechanical properties and exceptional optical qualities, such as high transparency and gloss.

[0050] The term "Bragg wavelength" means Bragg wavelength.

[0051] Holographic technology is widely used in technical fields such as holographic optical elements, data storage, high-end anti-counterfeiting, 3D displays and sensors. Holographic photopolymer materials serve as the material basis for holographic technology to achieve holographic recording and play a role in recording holographic information. Holographic photopolymer materials are usually formed by matrix polymers, photopolymerizable monomers and photoinitiator systems under light conditions. During this process, the photopolymerizable monomers undergo photopolymerization reactions to form photopolymers, which further form a phase-separated structure with the matrix polymer to form the basic optical element structure. Holographic optical elements made from holographic photopolymer materials with excellent performance have correspondingly better optical properties. Among them, the diffraction properties and light transmittance of holographic photopolymer materials are important factors affecting the optical properties of the holographic optical elements made from them.

[0052] The diffraction and transmittance properties of holographic photopolymer materials are not only related to the chemical structures of the photopolymer and matrix polymer, but more importantly, they also depend on the phase separation behavior between the photopolymer and matrix polymer. Typically, there is a conflicting relationship between transmittance and diffraction efficiency. This is because, while high diffraction efficiency can be achieved when the photopolymer and matrix polymer easily phase separate, it also tends to form larger photopolymer or matrix polymer particles in the material, resulting in reduced transmittance. Therefore, samples with high diffraction efficiency typically have lower transmittance, and samples with high transmittance often have lower diffraction efficiency.

[0053] At present, the research on the performance of holographic photopolymer materials is mostly focused on the study of the chemical structure of photopolymer monomers, but there is little research on the influence of the structure of photopolymer and matrix polymer and their relationship on the performance of holographic photopolymer materials, as well as the solution to the contradiction between transmittance and diffraction efficiency. In view of this, the embodiment of the present application provides a class of holographic photopolymer materials, the raw materials of which contain two photopolymerizable monomers, namely a first olefin monomer containing hydroxyl or amino groups, and a second olefin monomer with a high refractive index, and the two monomers are used to form a photopolymer through a photopolymerization reaction. Since the obtained photopolymer carries an appropriate amount of polar groups such as hydroxyl or amino groups, hydrogen bonds are formed between the photopolymer and the matrix polymer, thereby regulating the phase separation structure of the polymer multi-component system, thereby achieving the purpose of simultaneously improving the diffraction efficiency and transmittance.

[0054] Specifically, the holographic photopolymer material provided in the embodiment of the present application comprises a raw material including photopolymerizable monomers, the photopolymerizable monomers comprising at least a first olefin monomer and a second olefin monomer, and both photopolymerizable monomers contain olefin functional groups, and the two monomers can undergo photopolymerization reaction through the olefin functional groups to generate a photopolymer.

[0055] The structure of the first olefin monomer is shown in formula (1), which contains a site where photopolymerization reaction can occur, namely an olefin functional group. The ketone group therein is beneficial to enhancing the photoreactivity of the olefin double bond, thereby improving the generation efficiency of the holographic photopolymer and the holographic recording rate.

[0056]

[0057] Furthermore, in the first olefin monomer, at least one of R1 and R2 contains a hydroxyl group and / or an amino group. In this case, the photopolymer formed by the photopolymerization reaction of the first olefin monomer and the second olefin monomer contains at least one of the hydroxyl group and the amino group. Therefore, during the phase separation process, the photopolymer forms hydrogen bonds with the matrix polymer via the hydroxyl group and the amino group, thereby reducing the risk of localized aggregation of the holographic photopolymer material and the probability of the photopolymer or matrix polymer agglomerating to form large particles. This effectively improves the transparency of the holographic photopolymer material, enabling the holographic photopolymer material to have excellent diffraction efficiency and light transmittance.

[0058] As a possible embodiment, in the first olefin monomer, R1 is selected from a hydrogen atom or a methyl group, and R2 is selected from a hydroxyl group, an amino group, -O(CH2) n OH, -O(CH2) nNH2, wherein n is an integer from 1 to 6. Exemplarily, R2 may be -OCH2OH, -O(CH2)2OH, -O(CH2)3OH, -O(CH2)4OH, -O(CH2)5OH, -O(CH2)6OH, -OCH2NH2, -O(CH2)2NH2, -O(CH2)3NH2, -O(CH2)4NH2, -O(CH2)5NH2, -O(CH2)6NH2. In this case, the first olefin monomer formed and the photopolymer produced by the copolymerization of the first olefin monomer with the second olefin monomer contain hydroxyl groups and / or amino groups that can form hydrogen bonds with the matrix polymer, which can inhibit the aggregation of the photopolymer caused by phase separation, reduce light scattering, and improve the transmittance of the holographic photopolymer material and the optical component produced therefrom, such as a grating.

[0059] As a possible embodiment, the first olefin monomer is selected from at least one of the following structures:

[0060]

[0061] The substituents and corresponding structures of the first olefin monomer, as well as the English abbreviations and CAS numbers of some structures are shown in Table 1 below.

[0062] Table 1

[0063]

[0064]

[0065]

[0066]

[0067] The first olefin monomer contains hydroxyl or amino groups. After polymerization with the second olefin monomer to form a photopolymer, the hydroxyl or amino groups carried by the first olefin monomer are dispersed in the photopolymer. The hydroxyl or amino groups in the photopolymer hydrogen bond the photopolymer to the matrix polymer, reducing the risk of aggregation and ultimately improving the transparency of the material. The resulting holographic photopolymer material has both excellent diffraction efficiency and transparency.

[0068] In some embodiments, the first olefin monomer is selected from one or more of acrylamide (AM), 2-methacrylamide (MAM), hydroxyethyl acrylate (HEA), hydroxyethyl methacrylate (HEMA), hydroxypropyl acrylate (HPA), and hydroxypropyl methacrylate (HPMA). These preferred first olefin monomers are readily available commercial raw materials at low prices, thus reducing material costs.

[0069] As a possible embodiment, in the photopolymerizable monomer, the ratio of the total molar amount of hydroxyl groups and amino groups to the molar amount of olefin functional groups is 0.05:1 to 0.6:1. In this case, the photopolymer formed by the first olefin monomer and the second olefin monomer is distributed with appropriate amounts of hydroxyl groups and amino groups, which is beneficial to enhance the hydrogen bonding between the photopolymer and the matrix polymer, thereby effectively reducing the risk of agglomeration between the photopolymers and between the matrix polymers in the holographic photopolymer material, thereby improving the transparency of the material. The embodiment of the present application optimizes the phase separation structure of the photopolymer formed by the photopolymerization reaction and the matrix polymer by regulating the molar ratio of the polar groups of the photopolymerizable monomers, thereby effectively adjusting the contradiction between the transmittance and the diffraction efficiency of the holographic photopolymer material, and obtaining a holographic photopolymer material with both excellent refractive efficiency and transmittance. For example, in the photopolymerizable monomer, the ratio of the total molar amount of hydroxyl groups and amino groups to the molar amount of olefin functional groups can be 0.05:1, 0.08:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.55:1, 0.6:1, etc. In a preferred embodiment, in the photopolymerizable monomer, the ratio of the total molar amount of hydroxyl groups and amino groups to the molar amount of olefin functional groups can be 0.05:1 to 0.4:1, etc.; more preferably, the ratio of the total molar amount of hydroxyl groups and amino groups to the molar amount of olefin functional groups can be 0.1:1 to 0.3:1, etc.

[0070] The holographic photopolymer material provided in the embodiment of the present application also includes a second olefin monomer as its raw material. The second olefin monomer undergoes a photopolymerization reaction with the first olefin monomer to increase the refractive index of the obtained photopolymer, thereby increasing the refractive index difference between the photopolymer and the matrix polymer, and improving the diffraction efficiency of the holographic photopolymer material.

[0071] The structure of the second olefin monomer is shown in the following formula (2):

[0072]

[0073] In formula (2), R3 and R4 are each independently selected from a hydrogen atom or an atomic group, and R3 and R4 are not hydrogen atoms at the same time.

[0074] The second olefin monomer provided in the embodiment of the present application contains a site capable of undergoing photopolymerization reaction, namely an olefin functional group. In addition, the ester group is conjugated with the olefin double bond to increase the photoreactivity of the double bond, promote rapid holographic recording, and improve the quality of holographic optical elements.

[0075] In one possible embodiment, the refractive index of the second olefin monomer is greater than 1.5. In this case, the photopolymer formed by the photopolymerization reaction of the first and second olefin monomers has a higher refractive index, increasing the refractive index difference with the matrix polymer, which helps improve the diffraction efficiency of the holographic photopolymer material. Furthermore, combined with the first olefin monomer, especially the hydroxyl and amino groups introduced into the first olefin monomer, the photopolymer has excellent light transmittance, resulting in a holographic photopolymer with both excellent diffraction efficiency and light transmittance.

[0076] In the embodiment of the present application, the second olefin monomer can be a monofunctional photopolymerizable monomer that meets the structural requirements of formula (2), or a multifunctional photopolymerizable monomer that meets the structural requirements of formula (2). Wherein, a monofunctional photopolymerizable monomer refers to a photopolymerizable monomer having a CH2=C(R3)COO- skeleton structure in its structure; a multifunctional photopolymerizable monomer refers to a photopolymerizable monomer having two or more CH2=C(R3)COO- skeleton structures in its structure.

[0077] In one possible embodiment, the second olefin monomer is selected from a monofunctional photopolymerizable monomer. In some embodiments, R3 is selected from a hydrogen atom, a methyl group, or an aromatic group, and R4 is selected from a phenylethyl group, an o-phenylphenoxyethyl group, a 4-(1-methyl-1-phenylethyl)phenoxyethyl group, a 2,4,6-tribromophenyl group, a 2,4,6-tribromophenoxyethyl group, a pentabromophenyl group, a pentabromobenzyl group, a pentabromophenoxyethyl group, a 1-naphthyl group, a 2-naphthyl group, a 2-naphthyloxyethyl group, a 9-anthrylmethyl group, and a 9H-carbazole-9-ethyl group. The second olefin monomer formed by the above groups contains an aromatic group, which helps to increase the refractive index of the monomer, thereby increasing the refractive index difference between the photopolymer and the matrix polymer, and improving the diffraction efficiency of the holographic photopolymer material.

[0078] Exemplarily, the second olefin monomer is selected from at least one of the monofunctional photopolymerizable monomers shown in the following structure:

[0079] The Chinese names, English abbreviations and CAS numbers of the above-mentioned monofunctional photopolymerizable monomers are shown in Table 2 below.

[0080] Table 2

[0081]

[0082]

[0083]

[0084]

[0085] In one possible embodiment, the second olefin monomer is selected from a multifunctional photopolymerizable monomer. In some embodiments, the functional photopolymerizable monomer is selected from at least one of the following structures:

[0086]

[0087] The Chinese names, English abbreviations and CAS numbers of the above-mentioned multifunctional photopolymerizable monomers are shown in Table 3 below.

[0088] Table 3

[0089]

[0090]

[0091] In some embodiments, the second olefin monomer may contain at least one monofunctional photopolymerizable monomer and at least one multifunctional photopolymerizable monomer.

[0092] Exemplarily, the second olefin monomer comprises at least one of the monofunctional photopolymerizable monomers listed above, and at least one of the multifunctional photopolymerizable monomers listed above. The photopolymer formed by photopolymerization of the second olefin monomer with the first olefin monomer exhibits enhanced phase separation, facilitating an increase in the refractive index difference between coherent bright and dark regions. Furthermore, hydrogen bonding provided by the hydroxyl and / or amino groups of the first olefin monomer inhibits aggregation between the polymers and regulates the phase-separated microdomains of the photopolymer, thereby preventing excessive microdomain size from causing light scattering and, consequently, reducing the impact on the material's transmittance. This achieves a comprehensive improvement in the diffraction efficiency and transmittance of the holographic photopolymer material. Specifically, the principle behind the reduction in the first olefin monomer is that the hydroxyl and / or amino groups on the first olefin monomer physically crosslink the photopolymer with the matrix polymer, reducing aggregation between the two, thereby effectively improving the transmittance of the holographic photopolymer material and ultimately endowing the holographic photopolymer with excellent diffraction efficiency and transmittance.

[0093] In the embodiments of the present application, the refractive index of the photopolymer formed by the first olefin monomer and the second olefin monomer is higher than the refractive index of the matrix polymer, thereby achieving a high diffraction efficiency. The above-mentioned second olefin monomer provided in the embodiments of the present application has the advantage of a high refractive index (refractive index above 1.5). Therefore, after being photopolymerized with the first olefin monomer to form a photopolymer, the refractive index of the photopolymer can be increased, thereby improving the diffraction efficiency of the holographic photopolymer material. At the same time, the photopolymer is combined with the matrix polymer by means of the hydroxyl or amino groups on the first olefin monomer, reducing the agglomeration of the two, thereby effectively improving the transmittance of the holographic photopolymer material, and ultimately giving the holographic photopolymer excellent diffraction efficiency and light transmission performance. In addition, the high reactivity of acrylates or methacrylates is conducive to improving the photopolymerization rate and holographic recording rate.

[0094] In some embodiments, the second olefin monomer is selected from one or more of 2-phenoxyethyl acrylate (PHEA), α-(1-hydroxy-2-propenyl)-Ω-[1,1'-biphenyl]-2-oxy)-poly(oxy-1,2-ethanediyl) / o-phenylphenoxyethyl acrylate (OPPEA), 2-[4-(1-methyl-1-phenylethyl)phenoxy]ethyl acrylate (MPPEA), 2-naphthyl acrylate (ANPA), 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene (A-BPEF), 3-(9H-carbazol-9-yl)propane-1,2-diacrylate (CzEDA), and ethoxylated bisphenol A diacrylate (EO-BPADA). These preferred second olefin monomers have a higher refractive index and are mostly commercially available, facilitating low-cost, large-scale production of the material.

[0095] As a possible implementation of the present application, the molar ratio of the first olefin monomer to the second olefin monomer is 0.05:1 to 1.5:1. Since the hydroxyl and amino groups in the photopolymer formed by the first olefin monomer and the second olefin monomer are mainly derived from the first olefin monomer. Therefore, when the first olefin monomer and the second olefin monomer participate in the photopolymerization reaction in the above-mentioned molar ratio, the content of hydroxyl and amino groups in the obtained photopolymer can be effectively regulated, thereby facilitating the enhancement of hydrogen bonding between the photopolymer and the matrix polymer, reducing the risk of agglomeration between the photopolymers and the matrix polymers in the holographic photopolymer material, and thereby improving the transparency of the holographic photopolymer material.

[0096] In the embodiment of the present application, the holographic photopolymer material contains a matrix polymer, which not only gives the holographic photopolymer material processing characteristics such as flexible coating, but also serves as a component with a low refractive index to form a refractive index difference with the photopolymer monomer with a higher refractive index, thereby improving the diffraction efficiency of the holographic photopolymer material.

[0097] In one possible embodiment, the matrix polymer is selected from at least one of polyvinyl acetate (PVAc, CAS No.: 9003-20-7), polyvinyl butyral (PVB, CAS No.: 63148-65-2), polyvinyl acetal (PVA, CAS No.: 70775-95-0), polyvinyl formal (PVF, CAS No.: 9003-33-2), and polymethyl methacrylate (PMMA, CAS No.: 9011-14-7). On the one hand, the matrix polymer has a relatively low refractive index, which facilitates the formation of a large refractive index difference between the photopolymer formed with the first olefin monomer and the second olefin monomer, thereby improving the diffraction efficiency of the holographic photopolymer material. On the other hand, the first olefin monomer contains hydroxyl or amino groups, and the matrix polymer contains abundant binding sites. The hydroxyl or amino groups in the photopolymer can form hydrogen bonds with the matrix polymer through these binding sites, reducing the risk of agglomeration between the two polymers and facilitating improved light transmittance of the holographic photopolymer material.

[0098] In one possible implementation, the matrix polymer has a number-average molecular weight of 100,000 to 500,000. Lower matrix polymer number-average molecular weights can lead to severe agglomeration, resulting in low transmittance of the resulting holographic film. Excessively high matrix polymer number-average molecular weights can reduce the material's flexibility and processability. When the matrix polymer number-average molecular weight falls within this range, the resulting holographic photopolymer material can produce a holographic film with high transparency. In some preferred embodiments, the matrix polymer has a number-average molecular weight of 150,000 to 400,000; more preferably, the matrix polymer has a number-average molecular weight of 200,000 to 400,000.

[0099] In one possible embodiment, based on 100 parts by weight of the total weight of the matrix polymer and the photopolymerizable monomer, the matrix polymer comprises 20 to 80 parts by weight, and the photopolymerizable monomer comprises 20 to 80 parts by weight. In this case, the content of the photopolymer formed by photopolymerization of the photopolymerizable monomer and the matrix polymer is controlled within a reasonable range, which can improve the film-forming properties of the holographic photopolymer material, facilitate flexible processing of the material, such as roll-to-roll coating, and optimize the diffraction efficiency and light transmittance of the holographic photopolymer material. Exemplarily, the content of matrix polymer and photopolymerizable monomer can be: 20 parts matrix polymer, 80 parts photopolymerizable monomer; or 25 parts matrix polymer, 75 parts photopolymerizable monomer; or 30 parts matrix polymer, 70 parts photopolymerizable monomer; or 35 parts matrix polymer, 65 parts photopolymerizable monomer; or 40 parts matrix polymer, 60 parts photopolymerizable monomer; or 45 parts matrix polymer, 55 parts photopolymerizable monomer; or 50 parts matrix polymer, 50 parts photopolymerizable monomer; or 55 parts matrix polymer, 45 parts photopolymerizable monomer; or 60 parts matrix polymer, 40 parts photopolymerizable monomer; or 65 parts matrix polymer, 35 parts photopolymerizable monomer; or 70 parts matrix polymer, 30 parts photopolymerizable monomer; or 75 parts matrix polymer, 25 parts photopolymerizable monomer; or 80 parts matrix polymer, 20 parts photopolymerizable monomer, etc.

[0100] Increasing the photopolymerizable monomer content helps increase the refractive index difference between the coherent bright and dark areas. However, if the photopolymerizable monomer content is too high, residual photopolymer may remain in the dark areas, which in turn increases the refractive index of the dark areas, resulting in a decrease in the refractive index difference between the bright and dark areas. Therefore, a smaller difference in the content between the two is more beneficial for increasing the refractive index difference between the coherent bright and dark areas. In some preferred embodiments, the weight of the photopolymerizable monomer is 30 to 70 parts per 100 parts by weight of the total weight of the matrix polymer and the photopolymerizable monomer; more preferably, the weight of the photopolymerizable monomer is 40 to 60 parts by weight.

[0101] In the embodiments of the present application, a first olefin monomer and a second olefin monomer undergo photopolymerization reaction under a photoinitiator system to form a photopolymer. The photoinitiator system includes a photosensitizer and a co-initiator. Under illumination, the photosensitizer is activated by actinic radiation, and under the synergistic action of the co-initiator, the first olefin monomer and the second olefin monomer undergo photopolymerization reaction to form a photopolymer, thereby obtaining a holographic photopolymer material.

[0102] It should be understood that the photosensitizer is a photosensitizer that is sensitive to an excitation wavelength that excites the first olefin monomer and the second olefin monomer to undergo photopolymerization. In some embodiments, the photosensitizer is selected from at least one of acridine orange (AO, CAS No.: 494-38-2), eosin B (Eosin B, CAS No.: 548-24-3), erythrosine B (Erythrosine B, CAS No.: 16423-68-0), rose bengal (RB, CAS No.: 11121-48-5), rhodamine B (Rhodamine B, CAS No.: 81-88-9), methylene blue (MB, CAS No.: 61-73-4), 3,3'-carbonylbis(7-diethylaminocoumarin) (KCD, CAS No.: 63226-13-1), and 2,5-bis(4-diethylaminobenzylidene)cyclopentanone (DCB, CAS No.: 261360-66-1). In a preferred embodiment, the photosensitizer is one or more of 3,3'-carbonylbis(7-diethylaminocoumarin), Rose Bengal, and methylene blue. These photosensitizers have absorption spectra that closely match the laser emission wavelength, and they generate active centers quickly, enabling rapid photopolymerization.

[0103] In one possible embodiment, the amount of the photosensitizer added to the holographic photopolymer material raw material is 0.05-2 wt %, based on the total mass of the matrix polymer and the photopolymerizable monomer as 100%. For example, the amount of the photosensitizer added is 0.05%, 0.08%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, etc., based on the total mass of the matrix polymer and the photopolymerizable monomer as 100%. In a preferred embodiment, the amount of the photosensitizer added to the holographic photopolymer material raw material is 0.3-2 wt %.

[0104] In one possible embodiment, the coinitiator is a combination of an amine and a diphenyliodonium salt. This combination as a coinitiator has the advantage of high photoinitiation efficiency, which is beneficial for increasing the concentration of active centers and improving the photopolymerization reaction rate. In some embodiments, the coinitiator is selected from at least one of N-phenylglycine (NPG, CAS No.: 103-01-5), triethanolamine (TEA, CAS No.: 102-71-6), triisopropanolamine (TIPA, CAS No.: 122-20-3), methyldiethanolamine (MDEA, CAS No.: 105-59-9), diphenyliodonium chloride (DPI-Cl, CAS No.: 4673-26-1), and diphenyliodonium hexafluorophosphate (DPI-PF6, CAS No.: 58109-40-3). In a preferred embodiment, the coinitiator is one or more of methyldiethanolamine, diphenyliodonium chloride, and diphenyliodonium hexafluorophosphate. Preferably, the coinitiator has high photoinitiation efficiency, which is beneficial to increasing the concentration of active centers and the rate of photopolymerization reaction. Exemplarily, the coinitiator is selected from diphenyliodonium chloride (DPI-Cl) and methyldiethanolamine (MDEA).

[0105] In one possible embodiment, the amount of the co-initiator added to the holographic photopolymer material raw material is 0.5-5 wt%, based on the total mass of the matrix polymer and the photopolymerizable monomer as 100%. Exemplary amounts of the co-initiator added are 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, and so on, based on the total mass of the matrix polymer and the photopolymerizable monomer as 100%. In a preferred embodiment, the amount of the photosensitizer added to the holographic photopolymer material raw material is 1-2 wt%, based on the total mass of the matrix polymer and the photopolymerizable monomer as 100%.

[0106] For example, based on the total mass of the matrix polymer and the photopolymerizable monomer as 100%, the co-initiator is selected from 0.3-1.5 wt% of diphenyliodonium chloride (DPI-Cl) and 1-3 wt% of methyldiethanolamine (MDEA).

[0107] In an embodiment of the present application, the first olefin monomer and the second olefin monomer undergo photopolymerization reaction under the photoinitiator system, which can be carried out under visible light wavelength. As a possible embodiment, the excitation light wavelength of photopolymerization is 400nm to 800nm. Exemplarily, the excitation light wavelength of photopolymerization is 450nm to 480nm, 500nm to 560nm or 605nm to 700nm. The excitation light in these three ranges is the light wave band commonly used in holographic recording scenes. By selecting a photosensitizer that is sensitive to the excitation light in the above-mentioned bands, the photopolymerization between the first olefin monomer and the second olefin monomer can be effectively stimulated to expand the application scenarios. After the photoinitiator system is activated by the above-mentioned excitation light, the polymerizable groups of the first olefin monomer and the second olefin monomer undergo photopolymerization reaction to form a photopolymer. It should be understood that the photoinitiator system is a photoinitiator that can be activated by excitation light. The photosensitizer provided in the embodiments of the present application can be activated by excitation light in the range of 450 nm to 480 nm, 500 nm to 560 nm, or 605 nm to 700 nm, to trigger a photopolymerization reaction of the polymerizable groups of the first olefin monomer and the second olefin monomer.

[0108] As a possible embodiment of the present invention, during the photopolymerization process, the light intensity is 0.5 to 3 mW / cm 2 , with an exposure time of 10 to 30 seconds. Exposure at this light intensity efficiently activates the photosensitizer in the photoinitiator system, promoting the photopolymerization reaction between the first olefin monomer and the second olefin monomer, and improving the efficiency of photopolymer formation. It should be understood that the higher the light intensity for photopolymerization, the shorter the exposure time required for sufficient photopolymerization; conversely, the lower the light intensity for photopolymerization, the longer the exposure time required for sufficient photopolymerization.

[0109] In an embodiment of the present application, a raw material comprising a photopolymerizable monomer, a photosensitizer, and a co-initiator is exposed under light radiation conditions, and the polymerizable groups of the photopolymerizable monomer undergo photopolymerization to form a photopolymer. In this case, the holographic photopolymer material comprises a photopolymer. In some embodiments, after the photopolymerization reaction, the exposed material can be placed under a high-pressure mercury lamp, UV, or white light for bleaching to activate the unactivated photosensitizer, generate active centers, and fully react the unreacted monomers. Since the photosensitizer absorbs light and activates under the action of light radiation, the photosensitizer decolorizes, thereby reducing the effect of the residual photosensitizer on the transmittance of the holographic photopolymer material. In some embodiments, the bleaching time is 5 to 15 minutes. For example, the bleaching time can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, and other specific times.

[0110] In one possible embodiment, after the bleaching treatment, the bleached material is heated to further enhance the polymerization effect. In some embodiments, the polymerization effect of the photopolymerizable monomer is enhanced by baking in a convection oven at 50-100° C. for 5-20 minutes.

[0111] In one possible embodiment, the holographic photopolymer material is composed of a matrix polymer and a photopolymer. In this case, the optical element formed by the holographic photopolymer material is partitioned by the matrix polymer and the photopolymer to achieve a phase-separated basic grating structure.

[0112] In one possible embodiment, the photopolymer is produced by photopolymerizing a first olefin monomer and a second olefin monomer. In this case, the two monomers can not only endow the photopolymer with a rich content of hydroxyl or amino groups, providing sites for the photopolymer to bind to the matrix polymer, but also increase the refractive index of the photopolymer, widening the refractive index difference between the photopolymer and the matrix polymer, thereby improving the performance of the holographic photopolymer material.

[0113] As a preferred embodiment, the refractive index of the photopolymer is at least 0.1 higher than that of the matrix polymer. In this case, the refractive index difference between the coherent bright area and the coherent dark area is increased, thereby improving the diffraction efficiency of the material.

[0114] In a possible embodiment, in the holographic photopolymer material, the hydroxyl group and the amino group account for 1×10 -4 ~5×10 -3 By increasing and regulating the hydroxyl and amino group contents in the holographic photopolymer material, the amount of hydrogen bonding between the photopolymer and the matrix polymer can be controlled, effectively controlling the agglomeration between the photopolymers and the matrix polymers in the holographic photopolymer material, thereby improving the transparency of the photopolymer and the matrix polymer.

[0115] The holographic photopolymer material provided in the embodiments of the present application is copolymerized by adding a photopolymerizable monomer containing polar groups such as hydroxyl or amino groups and a high refractive index monomer, so that hydrogen bonds are formed between the generated photopolymer and the matrix polymer, thereby regulating the phase separation structure of the polymer multi-component system, thereby achieving the purpose of simultaneously improving the diffraction efficiency and transmittance.

[0116] The holographic photopolymer material provided in the embodiments of this application can be used to prepare a holographic optical element. Specifically, the embodiments of this application also provide a holographic optical element comprising the holographic photopolymer material. Due to the inclusion of the holographic photopolymer material, the holographic optical element provided in this application exhibits both excellent diffraction and light transmission properties. Specifically, the holographic optical element exhibits a diffraction efficiency exceeding 80% and a light transmittance exceeding 80% in the visible light band (400-800 nm).

[0117] For example, the holographic optical element may be a reflective holographic grating. For example, the holographic optical element may be prepared using a holographic photopolymer material by the following process:

[0118] S10. Provide the components according to the raw material formula of the holographic photopolymer material as described above and prepare a solution.

[0119] In this step, the raw material formulation for the holographic photopolymer material is as described above, including photopolymerizable monomers, a matrix polymer, and a photoinitiator system. To conserve space, this is not further detailed here. These raw materials are dispersed in a solvent to form a solution for the next step of film formation. While the choice of solvent is not specifically limited, methylene chloride is exemplary. In some embodiments, the raw materials are added to the solvent and mechanically stirred until completely dissolved.

[0120] S20. Forming the solution on a substrate and drying it to prepare a holographic photosensitive film.

[0121] In this step, the method for forming the solution on the substrate is not strictly limited and can be various methods used in conventional solution processing methods, including but not limited to drop coating, doctor blade coating, spin coating, inkjet printing, etc. Drying can remove the solvent from the resulting prefabricated film layer, forming a dense holographic photosensitive film. Exemplarily, the drying process can be natural drying.

[0122] In some embodiments, reference Figure 2 The solution is drop-coated on a substrate, coated, and dried to form a holographic photosensitive film. In some embodiments, an optical film may be coated on the surface of the holographic photosensitive film as a protective layer. Exemplarily, the optical film used as the protective layer may be a PET film.

[0123] S30. Perform interference processing on the holographic photosensitive film to prepare the holographic photosensitive film into a reflective holographic grating.

[0124] In this step, the principle of interference processing of the holographic photosensitive film is as follows: the holographic photosensitive film is irradiated with coherent light for holographic recording, the photopolymerizable monomers in the coherent bright area polymerize to form photopolymers, and some monomers in the coherent dark area diffuse into the coherent bright area to participate in the polymerization reaction, forming a basic grating structure through phase separation; further, after post-treatment such as ultraviolet light irradiation and heating, the photopolymerizable monomers in the system are completely consumed, the system further phase-separates, and a holographic grating with higher diffraction efficiency is obtained.

[0125] The embodiment of the present application can use a double-beam interference method to perform interference processing on the holographic photosensitive film, such as Figure 3A As shown, you can also use Figure 3B Single-beam interferometry shown.

[0126] The reflective holographic grating made of the above-mentioned holographic photopolymer material has both excellent diffraction and light transmission properties. Specifically, the diffraction efficiency of the reflective holographic grating is greater than 80%, and the light transmittance in the visible light band (400-800nm) is greater than 80%.

[0127] The present application also provides an optical device comprising the above-mentioned holographic optical element. Exemplarily, the optical device comprises a holographic display, a holographic notch filter, a data storage device, and a holographic anti-counterfeiting device.

[0128] Likewise, since the optical device provided in the embodiment of the present application contains the above-mentioned holographic optical element, the diffraction performance and light transmission performance of the optical device can be improved.

[0129] The following describes the details in conjunction with specific embodiments.

[0130] Example 1

[0131] A method for preparing a reflective holographic grating comprises the following steps:

[0132] (1) Weigh the raw material components of the photopolymer material according to the following formula

[0133] Matrix polymer: polyvinyl acetate (PVAc), molecular weight 400,000, accounting for 50 wt% of the total weight of matrix polymer and photopolymerizable monomers;

[0134] Photopolymerizable monomer: a mixture of o-phenylphenoxyethyl acrylate (OPPEA) and hydroxyethyl acrylate (HEA), wherein the molar ratio of hydroxyl groups to olefin functional groups is 0.2:1; the photopolymerizable monomer accounts for 50 wt% of the total weight of the matrix polymer and the photopolymerizable monomer, and the total weight of the matrix polymer and the photopolymerizable monomer is 100%;

[0135] Co-initiator: diphenyliodonium chloride (DPI-Cl) in an amount of 1 wt% based on the total weight of the matrix polymer and the photopolymerizable monomers, and methyldiethanolamine (MDEA) in an amount of 1.5 wt% based on the total weight of the matrix polymer and the photopolymerizable monomers;

[0136] Photosensitizer: Rose Bengal (RB) with a content of 0.8 wt% based on the total weight of the matrix polymer and the photopolymerizable monomer.

[0137] (2) Preparation of holographic photosensitive film

[0138] Under a safelight, polyvinyl acetate (PVAc) and dichloromethane (solvent) were added to a brown sample bottle. After mechanical stirring until completely dissolved, a mixture of hydroxyethyl acrylate (HEA) and o-phenylphenoxyethyl acrylate (OPPEA) was added. Diphenyliodonium chloride (DPI-Cl) and methyldiethanolamine (MDEA) were added as co-initiators, and mechanical stirring was performed to obtain a uniform mixed solution A. Rose Bengal (RB) was dissolved in methanol (solvent) as a photosensitizer and mixed with solution A to obtain a uniform mixed solution B.

[0139] Solution B was dropped onto a glass plate and coated using a 100μm wet film applicator. After coating, the resulting photosensitive film was allowed to stand for 15 minutes to allow the solvent to evaporate naturally, resulting in a holographic photosensitive film. A 50μm thick PET optical film was applied as a protective layer and the film was stored away from light until ready for use.

[0140] (3) Preparation of reflection holographic grating

[0141] The holographic photosensitive film was fixed in the optical path of the reflective holographic grating preparation, and an excitation light with a wavelength of 532 nm was used, with an intensity of 1 mW / cm per beam. 2 After holographic exposure, the photosensitive film was bleached under a high-pressure mercury lamp for 10 minutes and then baked in a convection oven at a heat enhancement temperature of 100°C for 5 minutes to enhance its performance, thereby producing a reflective holographic grating.

[0142] The performance of the reflective holographic grating prepared in Example 1 was tested using the following method:

[0143] (1) Transmittance test: With glass as the background, a UV-visible spectrophotometer is used to measure the transmittance of the reflective holographic grating in the 400-800nm ​​band.

[0144] (2) Calculate the diffraction efficiency using the following formula:

[0145]

[0146] Where η represents the diffraction efficiency, T v and T b are the transmittance of the reflective holographic grating at the Bragg wavelength and the transmittance of the baseline at the corresponding wavelength, respectively.

[0147] like Figure 4As shown in the schematic diagram of the transmittance curve of the reflective holographic grating, since the transmittance of the reflective holographic grating increases with the increase of wavelength except for the Bragg wavelength, the transmittance is generally the lowest at 400nm. Therefore, the transmittance of the reflective holographic grating at 400nm is mainly investigated. The transmittance curve of the reflective holographic grating prepared in Example 1 is shown in FIG. Figure 5 As shown by Figure 5 As can be seen, the transmittance of Example 1 in the visible light band (400-800nm) is greater than 80%. According to the above formula, the diffraction efficiency of the reflective holographic grating produced in Example 1 is approximately 93%. Therefore, Example 1 of the present application produces a reflective holographic grating that combines high transmittance with high diffraction efficiency, resolving the conflict between diffraction efficiency and transmittance to a certain extent.

[0148] Examples 2-4

[0149] A method for preparing a reflective holographic grating is basically the same as the preparation process of Example 1, except that:

[0150] The matrix polymer is polyvinyl acetate (PVAc) having a number average molecular weight of approximately 200,000; the photopolymerizable monomer is a mixture of 2-[4-(1-methyl-1-phenylethyl)phenoxy]ethyl acrylate (MPPEA) and hydroxyethyl methacrylate (HEMA), wherein the molar ratio of hydroxyl to olefin functional groups in the photopolymerizable monomer is 0.2:1; the co-initiator is selected from diphenyliodonium chloride (DPI-Cl) and methyldiethanolamine (MDEA), with contents of 1.0 wt% and 1.5 wt% respectively based on the total weight of the matrix polymer and the photopolymerizable monomer; the photosensitizer is selected from 3,3'-carbonylbis(7-diethylaminocoumarin) (KCD) with a content of 0.5 wt% based on the total weight of the matrix polymer and the photopolymerizable monomer; based on the total weight of the matrix polymer and the photopolymerizable monomer being 100%, the matrix polymers in Examples 2 to 4 respectively account for 40 wt%, 50 wt%, and 60 wt% of the total weight of the matrix polymer and the photopolymerizable monomer, and the remaining formulations in Examples 2 to 4 are the same;

[0151] During the preparation of the reflective holographic grating, the exposure conditions used were a laser wavelength of 460 nm and a light intensity of 0.8 mW / cm 2 The post-processing conditions used were to bleach the exposed material under a high-pressure mercury lamp for 5 minutes and then bake it in a convection oven at 70°C for 15 minutes to enhance its performance.

[0152] The reflective holographic gratings prepared in Examples 2 to 4 were subjected to performance tests, and the results were as follows: the transmittance of Example 2 at a wavelength of 400nm was 80%, and the diffraction efficiency was approximately 91%; the transmittance of Example 3 at a wavelength of 400nm was 85%, and the diffraction efficiency was approximately 88%; and the transmittance of Example 4 at a wavelength of 400nm was 86%, and the diffraction efficiency was approximately 81%.

[0153] Examples 5-11

[0154] A method for preparing a reflective holographic grating is basically the same as the preparation process of Example 1, except that:

[0155] The photopolymerizable monomer is a mixture of 2-phenoxyethyl acrylate (PHEA) and acrylamide (AM), wherein the molar ratio of amino to olefin functional groups in the photopolymerizable monomer is 0.3:1; the number average molecular weight of the matrix polymer is 200,000; the co-initiator is selected from diphenyliodonium hexafluorophosphate (DPI-PF6) and methyldiethanolamine (MDEA), with contents of 1.0 wt% and 1.5 wt% respectively based on the total weight of the matrix polymer and the photopolymerizable monomer; the photosensitizer is selected from rose bengal (RB), with a content of 0.8 wt% based on the total weight of the matrix polymer and the photopolymerizable monomer; in Examples 5 to 11, the type and content of the matrix polymer are different. Specifically, based on the total weight of the matrix polymer and the photopolymerizable monomer as 100%, the matrix polymers of Examples 5 to 11 are respectively 50 wt% PVAc (Example 5), 50 wt% PVA (Example 6), 50 wt% PVB (Example 7), 50 wt% PVF (Example 8), 50 wt% PMMA (Example 9), 40 wt% PVAc and 10 wt% PMMA (Example 10), and 30 wt% PVAc and 20 wt% PMMA (Example 11);

[0156] During the preparation of the reflective holographic grating, the exposure conditions used were a laser wavelength of 532 nm and a light intensity of 0.6 mW / cm 2 The post-processing conditions used were to bleach the exposed material under a high-pressure mercury lamp for 8 minutes and then bake it in a convection oven at 80°C for 10 minutes to enhance its performance.

[0157] The reflective holographic gratings prepared in Examples 5 to 11 were subjected to performance tests, and the results were as follows: the transmittance of Example 5 at a wavelength of 400nm was 85%, and the diffraction efficiency was approximately 88%; the transmittance of Example 6 at a wavelength of 400nm was 83%, and the diffraction efficiency was approximately 84%; the transmittance of Example 7 at a wavelength of 400nm was 82%, and the diffraction efficiency was approximately 81%; the transmittance of Example 8 at a wavelength of 400nm was 82%, and the diffraction efficiency was approximately 83%; the transmittance of Example 9 at a wavelength of 400nm was 84%, and the diffraction efficiency was approximately 82%; the transmittance of Example 10 at a wavelength of 400nm was 84%, and the diffraction efficiency was approximately 85%; and the transmittance of Example 11 at a wavelength of 400nm was 85%, and the diffraction efficiency was approximately 84%.

[0158] Examples 12-14

[0159] A method for preparing a reflective holographic grating is basically the same as the preparation process of Example 1, except that:

[0160] The matrix polymer is polyvinyl acetate (PVAc), the photopolymerizable monomer is a mixture of o-phenylphenoxyethyl acrylate (OPPEA) and hydroxypropyl methacrylate (HPMA), and the molar ratio of hydroxyl to olefin functional groups in the photopolymerizable monomer is 0.1:1; based on the total weight of the matrix polymer and the photopolymerizable monomer being 100%, the content of the matrix polymer is 60wt% and the content of the photopolymerizable monomer is 40wt%; the co-initiator is selected from dichlorodiphenyliodide, the content of which is 1.0wt% and 1.5wt% of the total weight of the matrix polymer and the photopolymerizable monomer, respectively. onium salt (DPI-Cl) and methyldiethanolamine (MDEA); the photosensitizer is selected from rose bengal (RB) in an amount of 1.2 wt% of the total weight of the matrix polymer and the photopolymerizable monomer; the molecular weight of the matrix polymers in Examples 12 to 14 is different, specifically, the molecular weight of the matrix polymer polyvinyl acetate (PVAc) in Example 12 is 200,000, the molecular weight of the matrix polymer polyvinyl acetate (PVAc) in Example 13 is 350,000, and the molecular weight of the matrix polymer polyvinyl acetate (PVAc) in Example 14 is 400,000;

[0161] During the preparation of the reflective holographic grating, the exposure conditions used were a laser wavelength of 460 nm and a light intensity of 1.5 mW / cm 2 The post-processing conditions used were to bleach the exposed material under a high-pressure mercury lamp for 10 minutes and then bake it in a convection oven at 100°C for 5 minutes to enhance its performance.

[0162] The reflective holographic gratings prepared in Examples 12 to 14 were subjected to performance tests, and the results were as follows: the transmittance of Example 12 at a wavelength of 400nm was 82%, and the diffraction efficiency was approximately 90%; the transmittance of Example 13 at a wavelength of 400nm was 85%, and the diffraction efficiency was approximately 88%; the transmittance of Example 14 at a wavelength of 400nm was 86%, and the diffraction efficiency was approximately 82%.

[0163] Examples 15-17

[0164] A method for preparing a reflective holographic grating is basically the same as the preparation process of Example 1, except that:

[0165] The matrix polymer is polyvinyl acetate (PVAc) with a number average molecular weight of about 350,000; the photopolymerizable monomer is a mixture of 2-phenoxyethyl acrylate (PHEA), 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene (A-BPEF) and hydroxypropyl acrylate (HPA); based on the total weight of the matrix polymer and the photopolymerizable monomer being 100%, the content of the matrix polymer is 50wt%, and the content of the photopolymerizable monomer is 50wt%; the co-initiator is selected from chlorine, which has a content of 1.0wt% and 1.5wt% of the total weight of the matrix polymer and the photopolymerizable monomer, respectively. The invention relates to a photopolymerization method comprising: preparing ...

[0166] During the preparation of the reflective holographic grating, the exposure conditions used were a laser wavelength of 460 nm and a light intensity of 1.0 mW / cm 2 The post-processing conditions used were to bleach the exposed material under a high-pressure mercury lamp for 5 minutes and then bake it in a convection oven at 80°C for 5 minutes to enhance its performance.

[0167] The reflective holographic gratings prepared in Examples 15 to 17 were subjected to performance tests, and the results were as follows: the transmittance of Example 15 at a wavelength of 400nm was 80%, and the diffraction efficiency was approximately 93%; the transmittance of Example 16 at a wavelength of 400nm was 85%, and the diffraction efficiency was approximately 88%; the transmittance of Example 17 at a wavelength of 400nm was 87%, and the diffraction efficiency was approximately 81%.

[0168] Examples 18-23

[0169] A method for preparing a reflective holographic grating is basically the same as the preparation process of Example 1, except that:

[0170] The matrix polymer is polyvinyl acetate (PVAc) with a number average molecular weight of about 400,000; in the photopolymerizable monomer, the molar ratio of hydroxyl or amino to olefin functional groups is 0.2:1; based on the total weight of the matrix polymer and the photopolymerizable monomer being 100%, the content of the matrix polymer is 50wt%, and the content of the photopolymerizable monomer is 50wt%; the co-initiator is selected from diphenyliodonium hexafluorophosphate (DPI-PF6) and methyldiethanolamine (MDEA) with contents of 1.0wt% and 1.5wt% of the total weight of the matrix polymer and the photopolymerizable monomer, respectively; the photosensitizer is selected from rose bengal (RB) with a content of 1.0wt% of the total weight of the matrix polymer and the photopolymerizable monomer; in Examples 18 to 23, the types of photopolymerizable monomers are different. Specifically, the photopolymerizable monomer in Example 18 is a mixture of 2-phenoxyethyl acrylate (PHEA) and acrylamide (AM), and in Example 19 The photopolymerizable monomer is a mixture of 2-phenoxyethyl acrylate (PHEA) and hydroxyethyl acrylate (HEA). In Example 20, the photopolymerizable monomer is a mixture of 2-phenoxyethyl acrylate (PHEA), 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene (A-BPEF) and hydroxypropyl acrylate (HPA). In Example 21, the photopolymerizable monomer is a mixture of o-phenylphenoxyethyl acrylate (OPPEA) and hydroxypropyl methacrylate (HPMA). In Example 22, the photopolymerizable monomer is a mixture of o-phenylphenoxyethyl acrylate (OPPEA) and hydroxyethyl methacrylate (HEMA). In Example 23, the photopolymerizable monomer is a mixture of o-phenylphenoxyethyl acrylate (OPPEA), 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene (A-BPEF) and 2-methylacrylamide (MAM).

[0171] During the preparation of the reflective holographic grating, the exposure conditions used were a laser wavelength of 532 nm and a light intensity of 0.5 mW / cm 2 The post-treatment conditions used were to bleach the exposed material under a high-pressure mercury lamp for 10 minutes and then bake it in a convection oven at 70°C for 15 minutes to enhance its performance.

[0172] The reflective holographic gratings prepared in Examples 18 to 23 were subjected to performance tests, and the results were as follows: the transmittance of Example 19 at a wavelength of 400nm was 82%, and the diffraction efficiency was approximately 85%; the transmittance of Example 20 at a wavelength of 400nm was 80%, and the diffraction efficiency was approximately 88%; the transmittance of Example 21 at a wavelength of 400nm was 85%, and the diffraction efficiency was approximately 84%; the transmittance of Example 22 at a wavelength of 400nm was 85%, and the diffraction efficiency was approximately 88%; the transmittance of Example 23 at a wavelength of 400nm was 82%, and the diffraction efficiency was approximately 91%; the transmittance of Example 24 at a wavelength of 400nm was 84%, and the diffraction efficiency was approximately 89%.

[0173] Examples 24-29

[0174] A method for preparing a reflective holographic grating is basically the same as the preparation process of Example 1, except that:

[0175] The matrix polymer is polyvinyl acetate (PVAc) with a number average molecular weight of about 200,000; in the photopolymerizable monomer, the molar ratio of hydroxyl or amino groups to olefin functional groups is 0.2:1; based on the total weight of the matrix polymer and the photopolymerizable monomer being 100%, the content of the matrix polymer is 50wt%, and the content of the photopolymerizable monomer is 50wt%; the co-initiator is selected from diphenyliodonium hexafluorophosphate (DPI-PF6) and methyldiethanolamine (MDEA) with contents of 1.0wt% and 1.5wt% of the total weight of the matrix polymer and the photopolymerizable monomer, respectively; the photosensitizer is selected from methylene blue (MB) with a content of 0.9wt% of the total weight of the matrix polymer and the photopolymerizable monomer; in Examples 24 to 29, the types of photopolymerizable monomers are different. Specifically, the photopolymerizable monomer in Example 24 is a mixture of 2-[4-(1-methyl-1-phenylethyl)phenoxy]ethyl acrylate (MPPEA) and 2-methacrylamide (MAM), and in Example 25 The photopolymerizable monomer in Example 2 is a mixture of 2-[4-(1-methyl-1-phenylethyl)phenoxy]ethyl acrylate (MPPEA) and hydroxyethyl methacrylate (HEMA), the photopolymerizable monomer in Example 26 is a mixture of 2-[4-(1-methyl-1-phenylethyl)phenoxy]ethyl acrylate (MPPEA), 3-(9H-carbazole-9-yl)propane-1,2-diacrylate (CzEDA) and hydroxypropyl acrylate (HPA), the photopolymerizable monomer in Example 27 is a mixture of 2-naphthyl acrylate (ANPA) and acrylamide (AM), the photopolymerizable monomer in Example 28 is a mixture of 2-naphthyl acrylate (ANPA) and 2-methylacrylamide (MAM), and the photopolymerizable monomer in Example 29 is a mixture of 2-naphthyl acrylate (ANPA), 3-(9H-carbazole-9-yl)propane-1,2-diacrylate (CzEDA) and hydroxyethyl acrylate (HEA).

[0176] During the preparation of the reflective holographic grating, the exposure conditions used were a laser wavelength of 640 nm and a light intensity of 3 mW / cm 2 The post-processing conditions used were to bleach the exposed material under a high-pressure mercury lamp for 10 minutes and then bake it in a convection oven at 90°C for 10 minutes to enhance its performance.

[0177] The reflective holographic gratings prepared in Examples 24 to 29 were subjected to performance tests, and the results were as follows: the transmittance of Example 24 at a wavelength of 400nm was 80%, and the diffraction efficiency was approximately 88%; the transmittance of Example 25 at a wavelength of 400nm was 82%, and the diffraction efficiency was approximately 85%; the transmittance of Example 26 at a wavelength of 400nm was 82%, and the diffraction efficiency was approximately 83%; the transmittance of Example 27 at a wavelength of 400nm was 81%, and the diffraction efficiency was approximately 81%; the transmittance of Example 28 at a wavelength of 400nm was 82%, and the diffraction efficiency was approximately 85%; the transmittance of Example 29 at a wavelength of 400nm was 83%, and the diffraction efficiency was approximately 86%.

[0178] Examples 30-38

[0179] A method for preparing a reflective holographic grating is basically the same as the preparation process of Example 1, except that:

[0180] The matrix polymer is polyvinyl acetate (PVAc), the photopolymerizable monomer is a mixture of o-phenylphenoxyethyl acrylate (OPPEA) and hydroxypropyl methacrylate (HPMA), and the molar ratio of hydroxyl to olefin functional groups in the photopolymerizable monomer is 0.1:1; based on the total weight of the matrix polymer and the photopolymerizable monomer being 100%, the content of the matrix polymer is 40wt%, and the content of the photopolymerizable monomer is 60wt%; the photosensitizer is selected from rose bengal (RB) having a content of 0.7wt% of the total weight of the matrix polymer and the photopolymerizable monomer; in Examples 30 to 38, the content of the co-initiator is different. Specifically, in Example 30, the co-initiator is 40wt%. The initiator is selected from diphenyliodonium chloride (DPI-Cl) and methyldiethanolamine (MDEA) in an amount of 1.0 wt% and 1.0 wt% of the total weight of the matrix polymer and the photopolymerizable monomer; in Example 31, the co-initiator is selected from diphenyliodonium chloride (DPI-Cl) and methyldiethanolamine (MDEA) in an amount of 1.0 wt% and 1.5 wt% of the total weight of the matrix polymer and the photopolymerizable monomer; in Example 32, the co-initiator is selected from diphenyliodonium chloride (DPI-Cl) and methyldiethanolamine (MDEA) in an amount of 1.0 wt% and 2.0 wt% of the total weight of the matrix polymer and the photopolymerizable monomer; in Example 33 The co-initiator is selected from diphenyliodonium chloride (DPI-Cl) and methyldiethanolamine (MDEA) with contents of 1.5 wt% and 1.0 wt% of the total weight of the matrix polymer and the photopolymerizable monomer; in Example 34, the co-initiator is selected from diphenyliodonium chloride (DPI-Cl) and methyldiethanolamine (MDEA) with contents of 1.5 wt% and 1.5 wt% of the total weight of the matrix polymer and the photopolymerizable monomer; in Example 35, the co-initiator is selected from diphenyliodonium chloride (DPI-Cl) and methyldiethanolamine (MDEA) with contents of 1.5 wt% and 2.0 wt% of the total weight of the matrix polymer and the photopolymerizable monomer; In Example 36, the co-initiator is selected from diphenyliodonium chloride (DPI-Cl) and methyldiethanolamine (MDEA) in an amount of 2.0 wt% and 1.0 wt% of the total weight of the matrix polymer and the photopolymerizable monomer; in Example 37, the co-initiator is selected from diphenyliodonium chloride (DPI-Cl) and methyldiethanolamine (MDEA) in an amount of 2.0 wt% and 1.5 wt% of the total weight of the matrix polymer and the photopolymerizable monomer; in Example 38, the co-initiator is selected from diphenyliodonium chloride (DPI-Cl) and methyldiethanolamine (MDEA) in an amount of 2.0 wt% and 2.0 wt% of the total weight of the matrix polymer and the photopolymerizable monomer.

[0181] During the preparation of the reflective holographic grating, the exposure conditions used were a laser wavelength of 532 nm and a light intensity of 1.5 mW / cm 2The post-treatment conditions used were to bleach the exposed material under a high-pressure mercury lamp for 5 minutes and then bake it in a convection oven at 50°C for 15 minutes to enhance its performance.

[0182] The reflective holographic gratings prepared in Examples 30 to 38 were subjected to performance tests, and the results were as follows: the transmittance of Example 30 at a wavelength of 400 nm was 80%, and the diffraction efficiency was approximately 82%; the transmittance of Example 31 at a wavelength of 400 nm was 85%, and the diffraction efficiency was approximately 88%; the transmittance of Example 32 at a wavelength of 400 nm was 83%, and the diffraction efficiency was approximately 87%; the transmittance of Example 33 at a wavelength of 400 nm was 80%, and the diffraction efficiency was approximately 81%; the transmittance of Example 34 at a wavelength of 400 nm was 81%, and the diffraction efficiency was approximately 86%; the transmittance of Example 35 at a wavelength of 400 nm was 82%, and the diffraction efficiency was approximately 82%; the transmittance of Example 36 at a wavelength of 400 nm was 82%, and the diffraction efficiency was approximately 80%; the transmittance of Example 37 at a wavelength of 400 nm was 85%, and the diffraction efficiency was approximately 83%; and the transmittance of Example 38 at a wavelength of 400 nm was 83%, and the diffraction efficiency was approximately 81%.

[0183] Comparative Example 1

[0184] A method for preparing a reflective holographic grating is basically the same as the preparation process of Example 1, except that:

[0185] The matrix polymer is polyvinyl acetate (PVAc) with a number average molecular weight of approximately 350,000; the photopolymerizable monomer is a mixture of 2-phenoxyethyl acrylate (PHEA), 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene (A-BPEF) and hydroxypropyl acrylate (HPA), and the photopolymerizable monomer does not contain a first olefin monomer; based on the total weight of the matrix polymer and the photopolymerizable monomer being 100%, the content of the matrix polymer is 50wt%, and the content of the photopolymerizable monomer is 50wt%; the co-initiator is selected from diphenyliodonium chloride (DPI-Cl) and methyldiethanolamine (MDEA), the contents of which are 1.0wt% and 1.5wt% of the total weight of the matrix polymer and the photopolymerizable monomer, respectively; and the photosensitizer is selected from 3,3'-carbonylbis(7-diethylaminocoumarin) (KCD), the content of which is 0.5wt% of the total weight of the matrix polymer and the photopolymerizable monomer.

[0186] During the preparation of the reflective holographic grating, the exposure conditions used were a laser wavelength of 460 nm and a light intensity of 1.0 mW / cm 2 The post-processing conditions used were to bleach the exposed material under a high-pressure mercury lamp for 5 minutes and then bake it in a convection oven at 80°C for 5 minutes to enhance its performance.

[0187] Performance testing of the reflective holographic grating produced in Comparative Example 1 revealed the following results: At a wavelength of 400 nm, the transmittance of Comparative Example 1 was 52%, and the diffraction efficiency was approximately 94%. This indicates that when the photopolymerizable monomer does not contain hydroxyl or amino groups, the resulting reflective holographic grating exhibits poor transmittance.

[0188] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A holographic photopolymer material, characterized in that: The raw materials of the holographic photopolymer material include a matrix polymer and a photopolymerizable monomer, wherein the photopolymerizable monomer includes a first olefin monomer and a second olefin monomer that can form a photopolymer through a photopolymerization reaction, wherein the structure of the first olefin monomer is as shown in formula (1), In formula (1), R1 is selected from hydrogen atom or methyl group, and R2 is selected from hydroxyl group, amino group, -O(CH2) n OH, -O(CH2) n NH2, wherein n is an integer from 1 to 6; The second olefin monomer is selected from at least one of the following structures: The refractive index of the photopolymer is higher than the refractive index of the matrix polymer; In the photopolymerizable monomer, the ratio of the total molar amount of hydroxyl groups and amino groups to the molar amount of olefin functional groups is 0.05:1 to 0.6:1; The molar ratio of the first olefin monomer to the second olefin monomer is 0.05:1 to 1.5:1; Based on 100 parts by weight of the total weight of the matrix polymer and the photopolymerizable monomer, the weight of the matrix polymer is 20 to 80 parts, and the weight of the photopolymerizable monomer is 20 to 80 parts.

2. The holographic photopolymer material according to claim 1, wherein The first olefin monomer is selected from at least one of the following structures:

3. The holographic photopolymer material according to any one of claims 1 to 2, characterized in that The refractive index of the second olefin monomer is greater than 1.

5.

4. The holographic photopolymer material according to claim 1, wherein The matrix polymer is selected from at least one of polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl formal and polymethyl methacrylate.

5. The holographic photopolymer material according to claim 1, wherein The raw materials of the holographic photopolymer material further include a photosensitizer and a co-initiator.

6. The holographic photopolymer material according to claim 1, wherein The holographic photopolymer material consists of the matrix polymer and the photopolymer.

7. The holographic photopolymer material according to claim 6, wherein The photopolymer is prepared by photopolymerizing the first olefin monomer and the second olefin monomer.

8. The holographic photopolymer material according to claim 7, wherein The wavelength of the excitation light for the photopolymerization is 400nm to 800nm.

9. The holographic photopolymer material according to claim 8, wherein During the photopolymerization process, the light intensity is 0.5 to 3 mW / cm 2 , the exposure time is 10 to 30 seconds.

10. The holographic photopolymer material according to any one of claims 6 to 9, characterized in that In the holographic photopolymer material, the hydroxyl group and the amino group account for 1×10 of the total mass of the holographic photopolymer material. -4 ~5×10 -3 mol / g.

11. A holographic optical element, characterized in that: Comprising the holographic photopolymer material according to any one of claims 1 to 10.

12. An optical device, characterized in that: Comprising the holographic optical element as claimed in claim 11.

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