A method of processing a diffraction grating

Abstract

The application discloses a processing method of a diffraction grating, which comprises the following steps: obtaining at least two transparent substrates; forming a grating structure on each of the at least two transparent substrates by imprinting, and forming a filling structure on the surface of the grating structure; the refractive index of the filling structure is higher than that of the grating structure; forming an adhesive material layer on the filling structure surface of one of the transparent substrates; facing the filling structure surface of another of the transparent substrates to the adhesive material layer, and aligning the grating structures of the at least two transparent substrates to bond the at least two transparent substrates to form a whole. The grating structure prepared by the processing method can effectively relieve or even eliminate light leakage.

Description

Technical Field

[0001] This application relates to the field of augmented reality, and more particularly to a method for fabricating a diffraction grating. Background Technology

[0002] Augmented reality is a technology that blends the real world with virtual information. Augmented reality display systems typically include micro-projectors and optical displays. The micro-projectors provide virtual display content for the augmented reality display system, which is then projected onto the viewer's eyes through the optical displays. The optical displays are usually transparent optical components, so that users can also see the real world through the optical displays at the same time.

[0003] In existing technologies, diffractive waveguides are commonly used as optical displays. However, since diffraction gratings simultaneously possess transmission and reflection orders oriented in opposite directions, the diffraction orders facing the human eye are effectively utilized, while the diffraction orders in the opposite direction cause light leakage. Theoretically, high aspect ratio oblique tooth gratings can alleviate or even eliminate light leakage, but it is difficult to obtain high aspect ratio oblique tooth gratings using existing imprinting processes. Summary of the Invention

[0004] This application provides a method for fabricating a diffraction grating. This method combines the advantages of imprinting while overcoming its limitations. The fabricated grating structure can effectively alleviate or even eliminate light leakage.

[0005] A method for fabricating a diffraction grating, the method comprising:

[0006] Obtain at least two transparent substrates;

[0007] A grating structure is formed on at least two transparent substrates by imprinting, and a filling structure is formed on the surface of the grating structure; the refractive index of the filling structure is higher than that of the grating structure.

[0008] An adhesive material layer is formed on the surface of the filling structure of one of the transparent substrates;

[0009] The filling structure surface of the other transparent substrate is oriented toward the adhesive material layer, and the grating structures of the at least two transparent substrates are aligned so that the at least two transparent substrates are bonded together to form a whole.

[0010] Implementably, the step of forming grating structures on at least two transparent substrates by imprinting and forming a filling structure on the surface of the grating structures includes:

[0011] Obtain an imprint template with a preset microstructure;

[0012] Resin material layers are formed on the at least two transparent substrates respectively;

[0013] The microstructure on the embossing template is transferred onto the resin material layer to form a grating structure;

[0014] An inorganic material is deposited on the surface of the grating structure to form a filling structure; the outer surface of the filling structure is flat, and the refractive index of the inorganic material is higher than that of the resin material layer.

[0015] Implementably, the step of forming grating structures on at least two transparent substrates by imprinting and forming a filling structure on the surface of the grating structures includes:

[0016] Obtain an imprint template with a preset microstructure;

[0017] A first resin material layer is formed on each of the at least two transparent substrates;

[0018] The microstructure on the embossing template is transferred onto the resin material layer to form a grating structure;

[0019] A second resin material is coated on the surface of the grating structure to form a filling structure; the surface of the filling structure is flat, and the refractive index of the second resin material is higher than that of the first resin material layer.

[0020] In practice, the at least two transparent substrates include a first transparent substrate and a second transparent substrate, wherein the second transparent substrate is a flexible transparent substrate;

[0021] The processing method further includes:

[0022] A grating structure is formed after a peelable adhesive layer is formed on the surface of the second transparent substrate.

[0023] Peel off the peelable adhesive layer and the second transparent substrate, and transfer the grating structure and filling structure of the second transparent substrate to the first transparent substrate.

[0024] Alternatively, the processing method may further include:

[0025] A third transparent substrate is obtained, wherein the third transparent substrate is a flexible transparent substrate;

[0026] A peelable adhesive layer is formed on the surface of the third transparent substrate, a grating structure is formed by imprinting on the peelable adhesive layer, and a filling structure is formed on the surface of the grating structure.

[0027] An adhesive material layer is formed on the surface of the filling structure of the first transparent substrate and / or the surface of the filling structure of the third transparent substrate, the filling structures of the first transparent substrate and the third transparent substrate are oriented toward each other, and the grating structure of the first transparent substrate is aligned with the grating structure of the third transparent substrate, so that the first transparent substrate and the third transparent substrate are bonded together to form a whole.

[0028] Peel off the peelable adhesive layer and the third transparent substrate, and transfer the grating structure and filling structure of the third transparent substrate to the first transparent substrate.

[0029] Implementably, the peelable adhesive layer is a photosensitive material or a thermosensitive material; the peeling of the peelable adhesive layer and the second transparent substrate includes:

[0030] The adhesiveness of the peelable adhesive layer is reduced by ultraviolet light or heating, so that the peelable adhesive layer and the second transparent substrate can be removed from the grating structure.

[0031] In practice, the grating periods of the grating structures on the at least two transparent substrates are consistent.

[0032] In practice, the grating duty cycle of the grating structures on different transparent substrates may be different.

[0033] In practice, the grating duty cycle may be different in different regions of the grating structure on one of the transparent substrates.

[0034] In practice, the grating tooth profiles of the grating structures on different transparent substrates are different.

[0035] This application provides a method for processing a diffraction grating. In this method, at least two transparent substrates are first obtained, and a grating structure is formed on each transparent substrate by imprinting. Then, a filling structure is formed on the surface of the grating structure. After forming an adhesive material layer on the surface of the filling structure of any at least one transparent substrate, the filling structure surfaces of the two transparent substrates are bonded together with the filling structure surfaces facing each other. Moreover, during bonding, the grating structures of the two transparent substrates are aligned. The overall structure formed by aligning and bonding two or more layers can achieve an equivalent higher aspect ratio, thereby effectively mitigating or even eliminating light leakage. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 A schematic diagram of the process flow for a method of fabricating a diffraction grating provided in an embodiment of this application;

[0038] Figure 2 A schematic diagram of the stripping step in another method for processing a diffraction grating provided in this application embodiment;

[0039] Figure 3 A schematic diagram of the grating structure fabricated by the processing method of the diffraction grating provided in an embodiment of this application;

[0040] Figure 4 A schematic diagram of a grating structure fabricated by a method for processing a diffraction grating according to another embodiment of this application;

[0041] Figure 5 Incident angle response diagrams of different grating structures prepared by a method for fabricating a diffraction grating according to an embodiment of this application;

[0042] Figure 6 A schematic diagram of a grating structure fabricated by a method for processing a diffraction grating according to another embodiment of this application;

[0043] Attached image labels:

[0044] 101: First transparent substrate; 102: First grating structure; 103: First filling structure;

[0045] 201: Second transparent substrate; 202: Second grating structure; 203: Second filling structure;

[0046] 301: Third transparent substrate; 302: Third grating structure; 303: Third filling structure;

[0047] 400: Adhesive material layer;

[0048] 500: Peelable adhesive layer. Detailed Implementation

[0049] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0050] The technical solution of this application will be described in detail below with reference to specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0051] This application provides a method for fabricating a diffraction grating, with reference to... Figure 1 Specifically, the fabrication method of the diffraction grating includes:

[0052] S10: Obtain at least two transparent substrates;

[0053] S20: A grating structure is formed on at least two transparent substrates by imprinting, and a filling structure is formed on the surface of the grating structure; the refractive index of the filling structure is higher than that of the grating structure.

[0054] S30: An adhesive material layer is formed on the surface of the filling structure of one of the transparent substrates;

[0055] S40: The filling structure surface of another transparent substrate is oriented toward the adhesive material layer, and the grating structures of at least two transparent substrates are aligned so that at least two transparent substrates are bonded together to form a whole.

[0056] The transparent substrate is made of a light-transmitting material, such as glass, PET, or PC. This application may obtain two or more transparent substrates, each with a structure fabricated on it before being stacked. This example uses two transparent substrates: a first transparent substrate 101 and a second transparent substrate 201, for illustration.

[0057] In practice, a grating structure is formed on at least two transparent substrates by imprinting, and a filling structure is formed on the surface of the grating structure, including: obtaining an imprinting template with a preset microstructure; forming a resin material layer on at least two transparent substrates; transferring the microstructure on the imprinting template onto the resin material layer to form a grating structure; depositing an inorganic material on the surface of the grating structure to form a filling structure; the outer surface of the filling structure is flat, and the refractive index of the inorganic material is higher than the refractive index of the resin material layer.

[0058] The imprinting template serves as the working template for imprinting the grating structure, and the imprinted grating structure is complementary to the microstructure on the imprinting template. Specifically, this application involves obtaining a pre-prepared imprinting template with a preset microstructure, and forming a resin material layer (i.e., an imprinting adhesive layer) on each transparent substrate. The imprinting template is then placed over the surface of the resin material layer and pressure is applied to transfer the microstructure from the imprinting template onto the resin material layer to form the grating structure. The resin material layer can be formed by spin coating, spraying, or inkjet printing. Further, after curing to form the grating structure, an inorganic material is deposited on the surface of the grating structure to form a filling structure. This filling structure completely fills the grooves of the grating structure and has a flat outer surface. The refractive index of the inorganic material is higher than that of the resin material layer.

[0059] In practice, a grating structure is formed on at least two transparent substrates by imprinting, and a filling structure is formed on the surface of the grating structure, including: obtaining an imprinting template with a preset microstructure; forming a first resin material layer on at least two transparent substrates; transferring the microstructure on the imprinting template onto the resin material layer to form a grating structure; coating the surface of the grating structure with a second resin material to form a filling structure; the surface of the filling structure is flat, and the refractive index of the second resin material is higher than the refractive index of the first resin material layer.

[0060] The imprinting template serves as the working template for imprinting the grating structure, and the imprinted grating structure is complementary to the microstructure on the imprinting template. Specifically, in this application, a pre-prepared imprinting template with a preset microstructure is obtained. A resin material layer, i.e., an imprinting adhesive layer, is formed on each transparent substrate. The imprinting template is then placed over the surface of the resin material layer and pressure is applied to transfer the microstructure on the imprinting template onto the resin material layer to form the grating structure. The resin material layer can be formed by spin coating, spraying, or inkjet printing. Further, after curing to form the grating structure, a second resin material is applied to the surface of the grating structure to form a filling structure. This filling structure completely fills the grooves of the grating structure and has a flat outer surface. The second resin material can be applied by spin coating, spraying, or inkjet printing, and the refractive index of the second resin material is higher than that of the first resin material layer.

[0061] For example, refer to Figure 1 In this example, a first transparent substrate 101 and a second transparent substrate 102 are obtained. A first grating structure 102 is formed on the first transparent substrate 101 by imprinting, and a first filling structure 103 is formed on the surface of the first grating structure 102, wherein the first filling structure 103 completely fills the groove of the first grating structure 102 and has a flat outer surface. At the same time, a second grating structure 202 is also formed on the second transparent substrate 102 by imprinting, and a second filling structure 203 is formed on the surface of the second grating structure 202, wherein the second filling structure 203 completely fills the groove of the second grating structure 202 and has a flat outer surface. Then, an adhesive material layer 400 is formed on the outer surface of the first filling structure 103 and / or the second filling structure 203, and the surfaces of the first filling structure 103 and the second filling structure 203 are bonded together, and the first grating structure 102 and the second grating structure 202 are aligned during bonding.

[0062] It should be noted that the alignment of the grating structure refers to the alignment along the extension direction of the groove in the grating structure and perpendicular to that extension direction. This alignment does not require absolute geometric alignment; offset schemes within permissible ranges are also claimed in this application, such as offsets on the order of hundreds of micrometers. Furthermore, the tooth profile of the grating structure is an oblique structure, such as parallel oblique teeth or trapezoidal oblique teeth.

[0063] In the aforementioned method for fabricating diffraction gratings, at least two transparent substrates are first obtained, and a grating structure is formed on each transparent substrate using an imprinting method. Then, a filling structure is formed on the surface of the grating structure. This allows for the bonding of two transparent substrates by forming an adhesive layer on the surface of the filling structure of at least one transparent substrate, with the filling structure surfaces facing each other to form an integral structure. Furthermore, during bonding, the grating structures of at least two transparent substrates are aligned. This integral structure, formed by aligning and bonding two or more layers, is equivalent to a grating structure with a higher aspect ratio, effectively mitigating or even eliminating light leakage.

[0064] In practice, when two or more transparent substrates are stacked, a maximum of two transparent substrates are retained, located at the outer ends of the bonded integral structure. One transparent substrate can serve as a waveguide substrate, where light is transmitted through total internal reflection; the other transparent substrate serves as a protective cover to protect the grating structure between the two transparent substrates from damage. Of course, in other examples, due to the filling structure on the grating structure, only the transparent substrate serving as the waveguide substrate may be retained.

[0065] In practice, at least two transparent substrates include a first transparent substrate and a second transparent substrate, wherein the second transparent substrate is a flexible transparent substrate; before step S20, the processing method of the diffraction grating provided in this application further includes: forming a grating structure after forming a peelable adhesive layer on the surface of the second transparent substrate; after step S40, the processing method of the diffraction grating provided in this application further includes: peeling off the peelable adhesive layer and the second transparent substrate, and transferring the grating structure and filling structure of the second transparent substrate to the first transparent substrate.

[0066] The flexible transparent substrate can be an easily peelable soft film material, such as PET, PC, or ultra-thin glass. A peelable adhesive layer is first formed on the flexible transparent substrate, followed by the formation of the grating structure. By reducing the adhesiveness of the peelable adhesive layer, the flexible transparent substrate and the grating structure can be quickly and easily separated.

[0067] Specifically, refer to Figure 2A peelable adhesive layer 500 is formed on the surface of the second transparent substrate 201, and an imprinting adhesive layer is formed on the surface of the peelable adhesive layer 500. The second grating structure 202 is formed by imprinting. After the surfaces of the first filling structure 103 and the second filling structure 203 are bonded together to form an integral structure, the adhesiveness of the peelable adhesive layer 500 is reduced, and the peelable adhesive layer 400 and the second transparent substrate 202 are peeled off. Alternatively, in other embodiments, the adhesiveness of the peelable adhesive layer 500 may be reduced first, the peelable adhesive layer 400 and the second transparent substrate 202 may be peeled off, and then the surfaces of the first filling structure 103 and the second filling structure 203 may be bonded together to form an integral structure.

[0068] In practice, the peelable adhesive layer is a photosensitive material or a thermosensitive material; peeling off the peelable adhesive layer and the second transparent substrate includes: reducing the adhesiveness of the peelable adhesive layer by ultraviolet light irradiation or heating, so as to remove the peelable adhesive layer and the second transparent substrate from the grating structure.

[0069] Specifically, the peelable adhesive layer can be a UV adhesive layer or a thermosetting adhesive layer, which can be debonded by UV, heating or other methods to reduce its stickiness and thus peel off from the grating structure.

[0070] It should be noted that the adhesive layer is made of a different material than the peelable adhesive layer, in order to avoid reducing the adhesive layer at the same time as reducing the peelable adhesive layer.

[0071] Furthermore, the fabrication method for the diffraction grating provided in this application further includes:

[0072] Obtain a third transparent substrate, which is a flexible transparent substrate;

[0073] A peelable adhesive layer is formed on the surface of a third transparent substrate, a grating structure is formed by imprinting on the peelable adhesive layer, and a filling structure is formed on the surface of the grating structure.

[0074] An adhesive material layer is formed on the surface of the filling structure of the first transparent substrate and / or the surface of the filling structure of the third transparent substrate, the filling structures of the first transparent substrate and the third transparent substrate are oriented toward each other, and the grating structure of the first transparent substrate is aligned with the grating structure of the third transparent substrate, so that the first transparent substrate and the third transparent substrate are bonded together to form an integral whole.

[0075] The peelable adhesive layer and the third transparent substrate are peeled off, and the grating structure and filling structure of the third transparent substrate are transferred to the first transparent substrate.

[0076] Specifically, refer to Figure 3The figure includes at least three grating structures: a first grating structure 102, a second grating structure 202, and a third grating structure 302. These three grating structures are formed in one step by imprinting on different light-transmitting substrates. In other embodiments, more grating structures may be included.

[0077] In the above embodiments, different grating structures are formed in one step on different transparent substrates by imprinting, enabling mass production based on nanoimprinting technology. Since the aspect ratio range of structures that can generally be mass-produced by nanoimprinting is within 3:1, this application can overcome the structural limitations of nanoimprinting by filling and stacking bonding, and process grating structures with equivalent higher aspect ratios. Furthermore, the overall structure prepared by this application is a multi-layer structure, which brings greater freedom to grating design, enabling regional grating modulation over a wider range and achieving better grating performance.

[0078] Furthermore, regarding the diffraction grating fabricated using the diffraction grating provided in this application:

[0079] In practice, the grating periods of the grating structures on at least two transparent substrates are consistent.

[0080] It should be noted that the grating periods of the multi-layer grating structure formed by stacking and bonding must be kept consistent in order to ensure the imaging effect of the diffraction grating used in the diffraction waveguide and avoid image ghosting.

[0081] In practice, the grating duty cycle of the grating structure on different transparent substrates is different.

[0082] Specifically, for grating structures, stacking grating structures with different duty cycles can achieve a relatively high diffraction efficiency distribution for incident light over a wider angular range. For example, refer to... Figure 4 As can be seen, the diffraction grating obtained by the fabrication method provided in this application comprises two grating layers, with different duty cycles for the different grating layers. (See also...) Figure 5 , Figure 5 The diffraction grating shown in the upper left figure has the same duty cycle in both layers. Figure 5 The image in the lower left corner is Figure 5 The top left figure shows the incident angle response diagram of the diffraction grating; Figure 5 The diffraction grating shown in the upper right figure has two layers with different duty cycles. Figure 5 The image at the bottom right is Figure 5 The incident angle response diagram of the diffraction grating shown in the upper right figure can be seen... Figure 5 The diffraction grating shown in the upper left figure has a narrow incident angle response bandwidth, but its diffraction efficiency is relatively higher. Figure 5The diffraction grating shown in the upper right figure has a relatively wider incident angle response bandwidth, but higher diffraction efficiency and is flat within the incident angle response bandwidth. Therefore, it can be seen that... Figure 5 The multilayer grating structure shown in the upper left figure, when used in a diffractive waveguide, can achieve higher diffraction efficiency within a small field of view; Figure 5 The multilayer grating structure shown in the upper right figure, when used in diffractive waveguides, can achieve a more uniform distribution of brightness and color over a wide field of view. In practical applications, different grating structures are selected based on performance requirements. Since the different layers of grating structures in this application are formed on different waveguide substrates, by adjusting the imprinting template, different grating structures can be formed using imprinting templates with the same or different duty cycles, thus creating multilayer grating structures with the same or different duty cycles, further improving other aspects of the performance of the fabricated diffraction grating.

[0083] In practice, the grating duty cycle is different in different regions of the grating structure on one of the transparent substrates.

[0084] Specifically, the grating structure in this application is formed by imprinting, using nanoimprinting for structural patterning. This allows for the generation of gratings with various tooth profiles and modulated regions in a single process. For the production of replicated gratings, nanoimprinting offers high cost-effectiveness. For example, see reference... Figure 6 As can be seen, the diffraction grating obtained by the processing method of the diffraction grating provided in this application includes a two-layer grating structure, and the grating duty cycle is different in different regions of the same layer grating structure. For example, the diffraction efficiency distribution of the diffraction grating is modulated by modulating the duty cycle.

[0085] In practice, the grating tooth shape of the grating structure on different transparent substrates is different.

[0086] The grating structure can be made of parallel helical teeth, trapezoidal helical teeth, etc. It should be noted that when helical tooth gratings are stacked, the tilt direction of the grating structures in different layers should be consistent.

[0087] In summary, the diffraction grating fabrication method provided in this application combines the advantages of nanoimprinting while overcoming its limitations. It first obtains at least two transparent substrates and forms a grating structure on each substrate using an imprinting method. Then, a filling structure is formed on the surface of the grating structure. This allows for bonding after an adhesive layer is formed on the surface of the filling structure of any at least one transparent substrate, and then the two transparent substrates are bonded together with their filling structure surfaces facing each other to form an integral structure. Furthermore, during bonding, the grating structures of at least two transparent substrates are aligned. This integral structure formed by aligning and bonding two or more layers can effectively achieve a higher aspect ratio grating structure, thereby effectively mitigating or even eliminating light leakage. Moreover, flexible transparent substrates can be used to remove them in subsequent steps, allowing for the stacking of more grating layers and reducing thickness. In addition, the multilayer structure provides greater freedom in grating design, enabling wider-range regional grating modulation and achieving superior grating performance.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this invention.

Claims

1. A method for fabricating a diffraction grating, characterized in that, The processing method includes: Obtain at least two transparent substrates; A grating structure is formed on at least two transparent substrates by imprinting, and a filling structure is formed on the surface of the grating structure; the refractive index of the filling structure is higher than that of the grating structure. An adhesive material layer is formed on the surface of the filling structure of one of the transparent substrates; The filling structure surface of the other transparent substrate is oriented toward the adhesive material layer, and the grating structures of the at least two transparent substrates are aligned so that the at least two transparent substrates are bonded together to form a whole.

2. The processing method according to claim 1, characterized in that, The process of forming grating structures on at least two transparent substrates by imprinting, and forming a filling structure on the surface of the grating structures, includes: Obtain an imprint template with a preset microstructure; Resin material layers are formed on the at least two transparent substrates respectively; The microstructure on the embossing template is transferred onto the resin material layer to form a grating structure; An inorganic material is deposited on the surface of the grating structure to form a filling structure; the outer surface of the filling structure is flat, and the refractive index of the inorganic material is higher than that of the resin material layer.

3. The processing method according to claim 1, characterized in that, The process of forming grating structures on at least two transparent substrates by imprinting, and forming a filling structure on the surface of the grating structures, includes: Obtain an imprint template with a preset microstructure; A first resin material layer is formed on each of the at least two transparent substrates; The microstructure on the embossing template is transferred onto the resin material layer to form a grating structure; A second resin material is coated on the surface of the grating structure to form a filling structure; the surface of the filling structure is flat, and the refractive index of the second resin material is higher than that of the first resin material layer.

4. The processing method according to claim 1, characterized in that, The at least two transparent substrates include a first transparent substrate and a second transparent substrate, wherein the second transparent substrate is a flexible transparent substrate; The processing method further includes: A grating structure is formed after a peelable adhesive layer is formed on the surface of the second transparent substrate. Peel off the peelable adhesive layer and the second transparent substrate, and transfer the grating structure and filling structure of the second transparent substrate to the first transparent substrate.

5. The processing method according to claim 4, characterized in that, The processing method further includes: A third transparent substrate is obtained, wherein the third transparent substrate is a flexible transparent substrate; A peelable adhesive layer is formed on the surface of the third transparent substrate, a grating structure is formed by imprinting on the peelable adhesive layer, and a filling structure is formed on the surface of the grating structure. An adhesive material layer is formed on the surface of the filling structure of the first transparent substrate and / or the surface of the filling structure of the third transparent substrate, the filling structures of the first transparent substrate and the third transparent substrate are oriented toward each other, and the grating structure of the first transparent substrate is aligned with the grating structure of the third transparent substrate, so that the first transparent substrate and the third transparent substrate are bonded together to form a whole. Peel off the peelable adhesive layer and the third transparent substrate, and transfer the grating structure and filling structure of the third transparent substrate to the first transparent substrate.

6. The processing method according to claim 4, characterized in that, The peelable adhesive layer is a photosensitive material or a thermosensitive material; the peeling of the peelable adhesive layer and the second transparent substrate includes: The adhesiveness of the peelable adhesive layer is reduced by ultraviolet light or heating, so that the peelable adhesive layer and the second transparent substrate can be removed from the grating structure.

7. The processing method according to claim 1, characterized in that, The grating periods of the grating structures on the at least two transparent substrates are consistent.

8. The processing method according to claim 1, characterized in that, The grating duty cycles of the grating structures on the different transparent substrates are different.

9. The processing method according to claim 1, characterized in that, The grating duty cycle is different in different regions of the grating structure on one of the transparent substrates.

10. The processing method according to claim 1, characterized in that, The grating tooth profiles of the grating structures on different transparent substrates are different.

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