Optical waveguide sheet, method for manufacturing the same, and augmented reality device

Abstract

The application provides an optical waveguide sheet, a preparation method thereof and an augmented reality device. The optical waveguide sheet comprises: a light transmission part, the light transmission part comprising a first transmission layer, a second transmission layer and a third transmission layer which are sequentially stacked; the refractive index of the first transmission layer is greater than the refractive index of the second transmission layer, and the refractive index of the third transmission layer is greater than the refractive index of the first transmission layer; and a grating part, the grating part comprising a light in-coupling part and a light out-coupling part, the light in-coupling part and the light out-coupling part being arranged on the surface of the first transmission layer away from the second transmission layer. The diffraction pattern of the optical waveguide sheet has better uniformity, thereby having better display effect.

Description

Technical Field

[0001] This application relates to the field of electronics, specifically to an optical waveguide sheet, its fabrication method, and an augmented reality device. Background Technology

[0002] Augmented reality (AR) technology, which combines virtual and real worlds, is finding increasingly widespread applications. In diffractive waveguides, light rays of different wavelengths and fields of view often possess different diffraction angles. This diffraction angle is generally the angle at which light propagates within the waveguide. A larger diffraction angle results in a greater propagation distance of light within the waveguide per period, and consequently, a smaller exit pupil density. In a single-layer waveguide, different propagation angles correspond to different exit pupil densities and different grating cycles. This leads to differences in the energy of the emitted light, affecting the uniformity of efficiency and color distribution within the waveguide's field of view. Furthermore, as the field of view increases, these differences become more pronounced, further deteriorating efficiency uniformity and color distribution. Summary of the Invention

[0003] To address the aforementioned issues, this application provides an optical waveguide sheet with a diffraction pattern exhibiting better uniformity, thereby resulting in improved display performance.

[0004] The first aspect of this application provides an optical waveguide sheet, which includes: A light-conducting section, comprising a first conductive layer, a second conductive layer, and a third conductive layer stacked sequentially; the refractive index of the first conductive layer is greater than that of the second conductive layer, and the refractive index of the third conductive layer is greater than that of the first conductive layer; and The grating section includes an optical coupler inlet and an optical coupler outlet, which are spaced apart on the surface of the first conductive layer away from the second conductive layer.

[0005] A second aspect of this application provides a method for fabricating an optical waveguide sheet, the optical waveguide sheet comprising an optically conductive portion and a grating portion, the optically conductive portion comprising a first conductive layer, a second conductive layer, and a third conductive layer stacked sequentially, wherein the refractive index of the first conductive layer is greater than the refractive index of the second conductive layer, and the refractive index of the third conductive layer is greater than the refractive index of the first conductive layer; the grating portion is disposed on the surface of the first conductive layer opposite to the second conductive layer; the method includes: The first conductive layer and the grating section are formed using a first molding method; The second conductive layer is formed using a second molding method; and The third conductive layer is formed using a first molding method; wherein the first molding method is injection molding or casting molding, and the second molding method is injection molding or casting molding, and the first molding method is different from the second molding method.

[0006] A third aspect of this application provides an augmented reality device, characterized in that it includes: A projection optical engine, wherein the projection optical engine is used to project an optical signal, the optical signal including image information; and The optical waveguide sheet described in this application embodiment is used to transmit the optical signal.

[0007] The optical waveguide sheet of this application embodiment includes an optical transmission section, which includes a first transmission layer, a second transmission layer, and a third transmission layer stacked sequentially. The refractive index of the first transmission layer is greater than that of the second transmission layer, and the refractive index of the third transmission layer is greater than that of the first transmission layer. This allows light rays incident from different fields of view or light rays of different wavelengths to propagate in different transmission layers of the optical waveguide sheet after being diffracted by a coupling grating. This allows for adjustment of the exit pupil density of light rays of different wavelengths or diffracted light rays from different fields of view, keeping the ratio of exit pupil densities within a small range, increasing the design freedom of the optical waveguide sheet. Compared to an optical waveguide sheet with a single-layer optical transmission section, this improves the uniformity of the diffraction pattern and enhances the light efficiency. Attached Figure Description

[0008] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a top view of the structure of an optical waveguide sheet according to an embodiment of this application.

[0009] Figure 2 This application describes an embodiment of an optical waveguide sheet along... Figure 1 A schematic diagram of the cross-sectional structure along the AA direction.

[0010] Figure 3 This is a schematic diagram of the optical path of an optical waveguide sheet according to an embodiment of this application.

[0011] Figure 4 This is a schematic flowchart of a method for fabricating an optical waveguide sheet according to an embodiment of this application.

[0012] Figure 5 This is a schematic flowchart of a method for fabricating an optical waveguide sheet according to another embodiment of this application.

[0013] Figure 6 This is a schematic diagram of the structure of the first mold according to an embodiment of this application.

[0014] Figure 7 This is a schematic diagram of the fabrication process of an optical waveguide sheet according to an embodiment of this application.

[0015] Figure 8 This is a schematic flowchart of a method for fabricating an optical waveguide sheet according to another embodiment of this application.

[0016] Figure 9 This is a schematic flowchart of a method for fabricating an optical waveguide sheet according to another embodiment of this application.

[0017] Figure 10 This is a schematic diagram of the fabrication process of the first conductive layer and grating section according to an embodiment of this application.

[0018] Figure 11 This is a schematic diagram of the fabrication process of the third conductive layer in one embodiment of this application.

[0019] Figure 12 This is a schematic diagram of the fabrication process of the second conductive layer according to an embodiment of this application.

[0020] Figure 13 This is a schematic diagram of the structure of an augmented reality device according to an embodiment of this application.

[0021] Figure 14 An augmented reality device according to an embodiment of this application Figure 13 A schematic diagram of the cross-sectional structure along the CC direction.

[0022] Figure 15 This is a circuit block diagram of an augmented reality device according to an embodiment of this application.

[0023] Explanation of reference numerals in the attached figures: 100-Optical waveguide sheet, 10-Optical transmission part, 11-First transmission layer, 13-Second transmission layer, 15-Third transmission layer, 30-Grating part, 31-Optical coupling entry part, 33-Optical coupling exit part, 100a-First mold, 10a-First sub-mold, 11a-Grating texture, 111a-Coupled grating texture, 113a-Coupled grating texture, 30a-Second sub-mold, 301a-First mold cavity, 100b-Second mold, 101b-Second mold cavity, 103b-Groove, 500-Augmented reality device, 510-Projection optical engine, 511-Display, 513-Lens, 530-Wearing component, 531-First wearing component, 533-Second wearing component, 550-Carrier, 540-Processor, 560-Memory. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0025] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0026] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0027] It should be noted that, for ease of explanation, the same reference numerals denote the same components in the embodiments of this application, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments.

[0028] Augmented reality (AR) is a technology that provides users with enhanced perception of reality by overlaying computer-generated images onto real-world images and then feeding them into the human eye. It is currently being used more and more widely.

[0029] An optical waveguide is a medium that guides light waves to propagate. As the main technical solution for augmented reality (AR) glasses, the optical waveguide can guide the light projected by a micro-projector to the front of the glasses, superimposing a virtual image on top of the real image in front of the viewer, thus providing augmented reality functionality.

[0030] In diffractive waveguides, light rays of different wavelengths and fields of view often possess different diffraction angles. This diffraction angle is generally the propagation angle of the light within the waveguide. A larger diffraction angle results in a greater propagation distance of the light within the waveguide per period, and consequently, a smaller exit pupil density. In a single-layer waveguide, different propagation angles correspond to different exit pupil densities and different grating cycles. This leads to differences in the energy of the final emitted light, thus affecting the uniformity of efficiency and color distribution within the waveguide's field of view. Furthermore, as the field of view increases, this difference becomes more pronounced, further deteriorating efficiency uniformity and color distribution.

[0031] Please see Figure 1 and Figure 2 This application provides an optical waveguide 100, which includes an optical transmission section 10 and a grating section 30. The optical transmission section 10 includes a first transmission layer 11, a second transmission layer 13, and a third transmission layer 15 stacked sequentially. The refractive index of the first transmission layer 11 is greater than that of the second transmission layer 13, and the refractive index of the third transmission layer 15 is greater than that of the first transmission layer 11. The grating section 30 includes an optical inlet section 31 and an optical outlet section 33, which are spaced apart on the surface of the first transmission layer 11 facing away from the second transmission layer 13.

[0032] Optionally, the optical input portion 31 is an input grating, and the optical output portion 33 is an output grating. The optical input portion 31 is used to receive the optical signal entering the optical waveguide 100 and couple the optical signal into the optical transmission portion 10 (i.e., the first transmission layer 11, the second transmission layer 13, and the third transmission layer 15), where the first transmission layer 11, the second transmission layer 13, and the third transmission layer 15 cooperate to transmit the optical signal; the optical output portion 33 is used to receive the optical signal transmitted by the first transmission layer 11, the second transmission layer 13, and the third transmission layer 15 and couple the optical signal out of the optical waveguide 100.

[0033] like Figure 3 As shown, in use, light is incident from the side of the third conductive layer 15 away from the second conductive layer 13. When light enters the light-conducting section 10 perpendicularly, total internal reflection does not occur between the first conductive layer 11 and the second conductive layer 13, nor between the third conductive layer 15 and the second conductive layer 13, allowing the light to propagate between the first conductive layer 11 and the third conductive layer 15. When light is incident at a certain angle, such as θ, total internal reflection occurs between the first conductive layer 11 and the second conductive layer 13, allowing the light to propagate only within the first conductive layer 11. After entering the light-conducting section 10, the incident light is transmitted through two paths, thereby improving the uniformity of the color pattern of the optical waveguide 100 and increasing the light efficiency.

[0034] The optical waveguide 100 of this application embodiment includes an optical transmission section 10, which includes a first transmission layer 11, a second transmission layer 13, and a third transmission layer 15 stacked sequentially. The refractive index of the first transmission layer 11 is greater than that of the second transmission layer 13, and the refractive index of the third transmission layer 15 is greater than that of the first transmission layer 11. This allows light rays incident from different fields of view or light rays of different wavelengths to propagate in different transmission layers of the optical waveguide 100 after being diffracted by a coupled grating. This allows for adjustment of the exit pupil density of light rays of different wavelengths or diffracted light rays from different fields of view, keeping the ratio of exit pupil densities within a small range, increasing the design freedom of the optical waveguide 100. Compared to an optical waveguide 100 with a single-layer optical transmission section 10, this improves the uniformity of the diffraction pattern and enhances the light efficiency of the optical waveguide 100.

[0035] Optionally, the first conductive layer 11, the second conductive layer 13, the third conductive layer 15, and the grating portion 30 are an integral structure. It can be understood that the first conductive layer 11, the second conductive layer 13, the third conductive layer 15, and the grating portion 30 are sequentially connected to form an integral structure. It can also be understood that the first conductive layer 11, the second conductive layer 13, the third conductive layer 15, the coupling grating portion 30, and the coupling out grating portion 30 are an integral structure. An integral structure can eliminate the bonding process between the individual resin layers, thereby avoiding misalignment problems caused by bonding.

[0036] Optionally, the refractive index of the first conductive layer 11 is equal to that of the third conductive layer 15. Compared to the case where the refractive indices of the first conductive layer 11 and the third conductive layer 15 are not equal, the first conductive layer 11 and the third conductive layer 15 only need to be prepared using the same materials and formula, which can simplify the raw material preparation process and reduce the manufacturing cost of the optical waveguide 100. In addition, when the refractive index of the first conductive layer 11 is equal to that of the third conductive layer 15, the resulting optical waveguide 100 has a better display effect.

[0037] Optionally, the refractive index n1 of the first conductive layer 11 ranges from 1.55 to 2.0. Specifically, the refractive index n1 of the first conductive layer 11 can be, but is not limited to, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2.0, etc. If the refractive index of the first conductive layer 11 is too small, the field of view (FOV) of the fabricated optical waveguide 100 will be too small; if the refractive index of the first conductive layer 11 is too large, it is difficult to achieve with current resin materials and processes.

[0038] Optionally, the refractive index n2 of the second conductive layer 13 ranges from 1.35 to 1.6. Specifically, the refractive index n2 of the second conductive layer 13 can be, but is not limited to, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, etc. If the refractive index of the second conductive layer 13 is too small, it is difficult to achieve with current resin materials and processes; if the refractive index of the second conductive layer 13 is too large, then the refractive index of the second conductive layer 13 will be close to that of the first conductive layer 11 or the third conductive layer 15, which is not conducive to improving the uniformity of the diffraction pattern of the optical waveguide 100.

[0039] Optionally, the refractive index n3 of the third conductive layer 15 ranges from 1.55 to 2.0. Specifically, the refractive index n3 of the third conductive layer 15 can be, but is not limited to, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2.0, etc. If the refractive index of the third conductive layer 15 is too small, the field of view (FOV) of the fabricated optical waveguide 100 will be too small; if the refractive index of the third conductive layer 15 is too large, it is difficult to achieve with current resin materials and processes.

[0040] Optionally, along the stacking direction of the first conductive layer 11, the second conductive layer 13, and the third conductive layer 15, the thickness of the first conductive layer 11 is greater than the thickness of the second conductive layer 13, and the thickness of the third conductive layer 15 is greater than the thickness of the second conductive layer 13. This can better improve the uniformity of the diffraction pattern of the optical waveguide 100.

[0041] In some embodiments, along the stacking direction of the first conductive layer 11, the second conductive layer 13, and the third conductive layer 15, the ratio h1 / h2 of the thickness h1 of the first conductive layer 11 to the thickness h2 of the second conductive layer 13 is in the range of 7:1 ≤ h1 / h2 ≤ 10:1. Specifically, the ratio h1 / h2 of the thickness h1 of the first conductive layer 11 to the thickness h2 of the second conductive layer 13 can be, but is not limited to, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1, or 10:1. A ratio that is too large or too small will reduce the uniformity of the diffraction pattern, failing to improve the uniformity of the diffraction pattern of the optical waveguide 100.

[0042] Optionally, along the stacking direction of the first conductive layer 11, the second conductive layer 13, and the third conductive layer 15, the thickness h1 of the first conductive layer 11 ranges from 0.2mm ≤ h1 ≤ 3mm. Specifically, the thickness of the first conductive layer 11 can be, but is not limited to, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.2mm, 1.5mm, 1.8mm, 2.0mm, 2.2mm, 2.5mm, 2.8mm, 3mm, etc. If the thickness of the first conductive layer 11 is too thick, the resulting optical waveguide 100 will be too heavy; if the thickness of the first conductive layer 11 is too thin, the first conductive layer 11 will be too soft and prone to deformation or bending, affecting the display effect of the image on the optical waveguide 100.

[0043] Optionally, along the stacking direction of the first conductive layer 11, the second conductive layer 13, and the third conductive layer 15, the thickness h2 of the second conductive layer 13 is in the range of 0.01mm ≤ h2 ≤ 0.1mm; specifically, the thickness of the second conductive layer 13 can be, but is not limited to, 0.01mm, 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 1.0mm, etc. If the thickness of the second conductive layer 13 is too thick, the light path changes too much when passing through the second conductive layer 13, making it more difficult to achieve the expected optical design goals and affecting the uniformity of the displayed image; if the thickness of the second conductive layer 13 is too thin, the structure of the light transmission part 10 is close to the structure of the first conductive layer 11 and the third conductive layer 15 bonded together, which also has a poor effect on improving the uniformity of the diffraction image.

[0044] In some embodiments, along the stacking direction of the first conductive layer 11, the second conductive layer 13, and the third conductive layer 15, the ratio h3 / h2 of the thickness h3 of the third conductive layer to the thickness h2 of the second conductive layer is in the range of 10 ≤ h3 / h2 ≤ 14:1. Specifically, the ratio h3 / h2 of the thickness h3 of the third conductive layer 15 to the thickness h2 of the second conductive layer 13 can be, but is not limited to, 10:1, 10.5:1, 11:1, 11.5:1, 12:1, 12.5:1, 13:1, 13.5:1, or 14:1. If the ratio h3 / h2 of the thickness h3 of the third conductive layer 15 to the thickness h2 of the second conductive layer 13 is too large or too small, it will reduce the uniformity of the diffraction pattern and fail to achieve the effect of improving the uniformity of the diffraction pattern of the optical waveguide 100.

[0045] Optionally, along the stacking direction of the first conductive layer 11, the second conductive layer 13, and the third conductive layer 15, the thickness h3 of the third conductive layer 15 ranges from 0.2mm ≤ h3 ≤ 3mm. Specifically, the thickness of the third conductive layer 15 can be, but is not limited to, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.2mm, 1.5mm, 1.8mm, 2.0mm, 2.2mm, 2.5mm, 2.8mm, 3mm, etc. If the thickness of the third conductive layer 15 is too thick, the resulting optical waveguide 100 will be too heavy; if the thickness of the third conductive layer 15 is too thin, the third conductive layer 15 will be too soft and prone to deformation or bending, affecting the display effect of the image on the optical waveguide 100.

[0046] In one specific embodiment, the thickness h1 of the first conductive layer 11 is 0.4 mm; the thickness h2 of the second conductive layer is 0.05 mm; and the thickness h3 of the third conductive layer is 0.4 mm.

[0047] In some embodiments, the thickness of the second conductive layer 13 is much smaller than the thicknesses of the first conductive layer 11 and the third conductive layer 15. Therefore, the thickness of the second conductive layer 13 can be ignored, and the optical waveguide sheet satisfies the following relationship: 2(h1+h3)tanθ1=2h3×tanθ2; and θ2≥sin -1 (n2 / n1); Wherein, n1 is the refractive index of the first conductive layer, n2 is the refractive index of the second conductive layer, θ1 is the diffraction angle in the single-layer optical conductive part when the light is incident perpendicularly on the optical waveguide sheet when the optical conductive part is a single layer with a thickness of h1+h3 and a refractive index of n1; θ2 is the diffraction angle of the light in the optical waveguide sheet.

[0048] When the optical waveguide 100 satisfies the above relationship, the uniformity of the diffraction pattern of the optical waveguide 100 can be improved, and the optical efficiency of the optical waveguide 100 can be enhanced.

[0049] Optionally, the first conductive layer 11, the second conductive layer 13, and the third conductive layer 15 are all resin layers. Compared to the glass waveguide sheet 100, the waveguide sheet 100 of this application is made of resin, which is lighter, has better drop resistance, and has lower manufacturing cost.

[0050] In some embodiments, the first conductive layer 11 and the third conductive layer 15 are both thermosetting resin layers, and the second conductive layer 13 is a thermoplastic resin layer. In other embodiments, the first conductive layer 11 and the third conductive layer 15 are both thermoplastic resin layers, and the second conductive layer 13 is a thermosetting resin layer. By alternating the use of thermosetting and thermoplastic resin layers, the light-conducting part 10 is fabricated, thereby enabling the fabrication of an integrated structure, and the surface flatness of each resin layer can meet the requirements of optical-grade flatness.

[0051] Optionally, the thermoplastic resin layer may include, but is not limited to, polycarbonate (PC). The thermosetting resin layer is obtained by curing a thermosetting resin adhesive. The thermosetting resin adhesive includes thermosetting resin monomers and a curing agent, wherein the thermosetting resin monomers include at least one selected from propylene carbonate, allyl diethylene glycol carbonate, acrylonitrile, ethylene glycol dimethacrylate, allyl acrylate, diallyl phthalate, and carbamate. The curing agent includes at least one selected from tert-butyl peroxynedecanoate, isophorone diamine, ethylenediamine, and methylene dicyclohexaneamine. Optionally, the thermosetting resin adhesive also includes at least one selected from mold release agents and antioxidants.

[0052] Optionally, the refractive index of the first conductive layer 11 and the third conductive layer 15 can be adjusted by adding a refractive index modifier with a high refractive index, such as a white metal oxide, like titanium dioxide or zirconium dioxide, to the thermosetting resin layer or thermoplastic resin layer. The refractive index of the first conductive layer 11 or the third conductive layer 15 can be adjusted by regulating the amount of titanium dioxide or zirconium dioxide added to the first conductive layer 11 and the third conductive layer 15 (e.g., the amount (mass content) of titanium dioxide or zirconium dioxide is 0.5% to 10%).

[0053] The optical waveguide 100 of this application embodiment can be prepared by the methods described in the following embodiments of this application. In addition, it can also be prepared by other methods. The preparation methods of this application embodiment are merely one or more preparation methods of the optical waveguide 100 of this application and should not be construed as limiting the optical waveguide 100 provided in the embodiments of this application.

[0054] Please see Figure 4 This application provides a method for fabricating an optical waveguide 100, which includes an optical transmission portion 10 and a grating portion 30. The optical transmission portion 10 includes a first transmission layer 11, a second transmission layer 13, and a third transmission layer 15 stacked sequentially. The refractive index of the first transmission layer 11 is greater than that of the second transmission layer 13, and the refractive index of the third transmission layer 15 is greater than that of the first transmission layer 11. The grating portion 30 is disposed on the surface of the first transmission layer 11 facing away from the second transmission layer 13. The method includes: S201, the first conductive layer 11 and the grating portion 30 are formed using a first molding method; S202, forming the second conductive layer 13 using a second molding method; and S203, the third conductive layer 15 is formed using a first molding method; wherein the first molding method is injection molding or casting molding, the second molding method is injection molding or casting molding, and the first molding method is different from the second molding method.

[0055] It should be noted that there is no specific order among S201, S202, and S203. The order of S201, S202, and S203 can be adjusted according to the different first molding method and the second molding method. In this embodiment and... Figure 4 The method described herein is illustrated in the order of S201, S202, and S203, and should not be construed as limiting the scope of protection of this application.

[0056] Optionally, the grating section 30 includes an optical coupler inlet 31 and an optical coupler outlet 33, which are spaced apart on the surface of the first conductive layer 11 away from the second conductive layer 13.

[0057] The optical waveguide 100 fabricated by the method of this application includes an optical transmission section 10, which comprises a first transmission layer 11, a second transmission layer 13, and a third transmission layer 15 stacked sequentially. The refractive index of the first transmission layer 11 is greater than that of the second transmission layer 13, and the refractive index of the third transmission layer 15 is greater than that of the first transmission layer 11. This allows light rays incident from different fields of view or light rays of different wavelengths to propagate in different resin layers of the optical waveguide 100 after diffraction by a coupling grating. This allows for adjustment of the exit pupil density of light rays of different wavelengths or diffracted light rays from different fields of view, keeping the ratio of exit pupil densities within a small range, increasing the design freedom of the optical waveguide 100. Compared to an optical waveguide 100 with a single-layer optical transmission section 10, this improves the uniformity of the diffraction pattern and enhances light efficiency. Furthermore, the optical waveguide 100 of this application is made of resin, making it lighter, more drop-resistant, and lower in manufacturing cost. The first conductive layer 11, the second conductive layer 13, the third conductive layer 15, and the grating portion 30 of the optical waveguide sheet 100 fabricated in this application are an integral structure. The first conductive layer 11, the second conductive layer 13, and the third conductive layer 15 do not require bonding between each other, eliminating the bonding process and avoiding misalignment caused by bonding. Furthermore, the fabrication method of this application, through the alternating combination of injection molding and casting molding processes, ensures that the surfaces of the first conductive layer 11, the second conductive layer 13, and the third conductive layer 15 all achieve optical-grade flatness.

[0058] Please see Figures 5 to 7 The first molding method is casting molding, and the second molding method is injection molding. The method for preparing the optical waveguide sheet 100 provided in this application embodiment includes: S301, such as Figure 6 As shown, a first mold 100a is provided. The first mold 100a includes a first sub-mold 10a and a second sub-mold 30a. The first sub-mold 10a and the second sub-mold 30a form a first mold cavity 301a. The first sub-mold 10a has a grating texture 11a facing the first mold cavity 301a. The grating texture 11a is complementary to the structure of the grating portion 30. The term "structural complementarity" in this application refers to the situation where, when two structurally complementary components are fitted together, the protrusion of one component precisely fills the groove of the other component, and they are fitted together.

[0059] Understandably, the surface of the second sub-mold 30a has a grating texture 11a, and the surface of the second sub-mold 30a with the grating texture 11a and the first sub-mold 10a together form the first mold cavity 301a.

[0060] Optionally, the grating texture 11a includes an input grating texture 111a and an output grating texture 113a, wherein the input grating texture 111a is structurally complementary to the optical input portion 31, and the output grating texture 113a is structurally complementary to the optical output portion 33.

[0061] S302, inject the first thermosetting resin liquid into the first mold cavity 301a; Optionally, the first thermosetting resin adhesive may include a thermosetting resin monomer and a curing agent. The thermosetting resin monomer includes at least one selected from propylene carbonate, allyl diethylene glycol carbonate, acrylonitrile, ethylene glycol dimethacrylate, allyl acrylate, diallyl phthalate, and carbamate. The curing agent includes at least one selected from tert-butyl peroxynedecanoate, isophorone diamine, ethylenediamine, and methylenebicyclohexaneamine.

[0062] Optionally, the first thermosetting resin liquid also includes at least one of a release agent, an antioxidant, etc.

[0063] Optionally, the first thermosetting resin adhesive further includes a refractive index modifier, which includes at least one of titanium dioxide or zirconium dioxide, to give the first conductive layer 11 a high refractive index.

[0064] Optionally, after the thermosetting resin monomer, curing agent, release agent, antioxidant, and refractive index modifier are stirred evenly, vacuum degassing is performed under vacuum conditions to remove dissolved air from the material. The material is then ready for use after degassing.

[0065] In one specific embodiment, the first thermosetting resin adhesive is prepared by the following steps: weigh 10g of propylene carbonate, 5g of allyl diethylene glycol carbonate, 4.8g of carbamate, 0.5g of isophorone diamine, 0.3g of methylene dicyclohexaneamine, 0.01g of glyceryl monooleate, and 0.01g of di-tert-butyl-p-cresol, respectively, and stir to mix evenly; degas under a vacuum of 100 Pa for 20 min.

[0066] S303, the first thermosetting resin adhesive is cured to obtain the first conductive layer 11 and the grating portion 30; Optionally, the first thermosetting resin liquid is heated (e.g., to 70°C to 120°C) to cause the thermosetting resin monomers and the curing agent to undergo a polymerization reaction, thereby forming a thermosetting resin layer, namely the first conductive layer 11 and the grating portion 30 of the integral structure.

[0067] In one specific embodiment, the first thermosetting resin adhesive is gradually heated from room temperature to 80°C over 4 hours; held at 80°C for 5 hours; gradually heated from 80°C to 100°C over 3 hours; gradually heated from 100°C to 120°C over 2 hours; held at 120°C for 7 hours; and gradually cooled to 50°C over 2 hours.

[0068] Optionally, before heating and curing the first thermosetting resin adhesive, the first sub-mold 10a is positioned below the second sub-mold 30a along the direction of gravity, and the first thermosetting resin adhesive is cured to obtain the first conductive layer 11 and the grating portion 30. When the thermosetting resin adhesive undergoes a polymerization reaction and cures, volume shrinkage occurs, causing the first sub-mold 10a with the grating texture 11a to be positioned below the second sub-mold 30a without the grating texture 11a under the force of gravity. This allows for a better obtaining of the grating portion 30 with the predetermined structure, preventing errors between the grating texture 11a and the predetermined structure due to volume shrinkage.

[0069] S304, a second conductive layer 13 is formed by injection molding on the surface of the first conductive layer 11 that is away from the grating portion 30; Optionally, a thermoplastic resin, such as polycarbonate, is used to form the second conductive layer 13 on the surface of the first conductive layer 11 facing away from the grating portion 30 by high-pressure injection molding. The injection molding temperature of polycarbonate is around 250°C, which is much lower than the softening or deformation temperature of the thermosetting resin layer. Therefore, when the second conductive layer 13 is injection molded, the first conductive layer 11 can still maintain its original film structure, and the surface flatness will not be affected by the injection molding. In this embodiment, the second conductive layer 13 is not prepared by casting because the raw material for casting is a thermosetting resin liquid. During the polymerization reaction of the thermosetting resin liquid, volume shrinkage occurs, resulting in an uneven surface of the second conductive layer 13. It needs to be polished to achieve optical-grade flatness. However, the thickness of the second conductive layer 13 itself is only 0.01 mm to 0.1 mm, which makes it very easy to be consumed during the polishing process, and it is difficult to control the thickness of the second conductive layer 13. Therefore, high-pressure injection molding is required to ensure that the surface of the second conductive layer 13 facing away from the first conductive layer 11 can maintain optical-grade flatness without polishing.

[0070] S305, injecting a second thermosetting resin adhesive onto the surface of the second conductive layer 13 opposite to the first conductive layer 11; and Optionally, the second thermosetting resin adhesive may include thermosetting resin monomers and a curing agent. The thermosetting resin monomers include at least one selected from propylene carbonate, allyl diethylene glycol carbonate, acrylonitrile, ethylene glycol dimethacrylate, allyl acrylate, diallyl phthalate, and carbamate. The curing agent includes at least one selected from tert-butyl peroxynedecanoate, isophorone diamine, ethylenediamine, and methylenebicyclohexaneamine.

[0071] Optionally, the second thermosetting resin liquid may also include at least one of a release agent, an antioxidant, etc.

[0072] Optionally, the second thermosetting resin solution further includes at least one of titanium dioxide or zirconium dioxide to give the third conductive layer 15 a higher refractive index.

[0073] For a detailed description of other aspects of the second thermosetting resin solution, please refer to the description of the first thermoplastic resin in the above embodiments, which will not be repeated here.

[0074] S306, the second thermosetting resin adhesive is cured to obtain the third conductive layer 15.

[0075] Optionally, the second thermosetting resin solution is heated (e.g., to 70°C to 120°C) to cause the thermosetting resin monomers to polymerize with the curing agent, thereby forming a thermosetting resin layer, namely the third conductive layer 15.

[0076] The curing temperature of thermosetting resin adhesive is generally between 70℃ and 120℃, which is much lower than that of the second conductive layer 13 (whose melting temperature is generally higher than 200℃). Therefore, during the curing process of the second thermosetting resin adhesive, the second conductive layer 13 will not soften or deform, and the surface smoothness of the second conductive layer 13 can be well maintained.

[0077] It should be noted that the first conductive layer 11, the second conductive layer 13, and the third conductive layer 15 cannot all be prepared by injection molding. Therefore, when the second conductive layer 13 is injection molded onto the first conductive layer 11, since the injection temperature is above the melting temperature of the thermoplastic resin, if the second conductive layer 13 is injection molded onto the surface of the first conductive layer 11, the molten thermoplastic resin will soften the surface of the first conductive layer 11 upon contact with it. This would prevent the flatness of the contact surface between the first conductive layer 11 and the second conductive layer 13 from being maintained, resulting in a change in the interface between the first conductive layer 11 and the second conductive layer 13, and the optical-grade flatness would no longer be maintained. Furthermore, some of the resin between the first conductive layer 11 and the second conductive layer 13 might even melt, failing to meet optical requirements. However, in this embodiment, the second conductive layer 13 is a thermosetting resin layer. The temperature at which the second conductive layer 13 is formed is lower, preventing a change in the interface between the first conductive layer 11 and the second conductive layer 13, thus maintaining better optical-grade flatness.

[0078] Please see Figure 8 The first molding method is casting molding, and the second molding method is injection molding. The method for preparing the optical waveguide sheet 100 provided in this application embodiment includes: S401, a first mold 100a is provided, the first mold 100a includes a first sub-mold 10a and a second sub-mold 30a, the first sub-mold 10a and the second sub-mold 30a surround a first mold cavity 301a, the first sub-mold 10a has a grating texture 11a facing the first mold cavity 301a, the grating texture 11a is complementary to the structure of the grating portion 30; S402, inject the first thermosetting resin liquid into the first mold cavity 301a; S403, along the direction of gravity, the first sub-mold 10a is positioned below the second sub-mold 30a, and the first thermosetting resin is cured to obtain the first conductive layer 11 and the grating portion 30. For a detailed description of S401 to S403, please refer to the description of the corresponding parts of the above embodiments, which will not be repeated here.

[0079] S404, Polish the surface of the first conductive layer 11 away from the grating portion 30 so that the surface accuracy PV1 of the first conductive layer 11 away from the grating portion 30 is PV1≤15nm; The term "PV" refers to the difference between the highest and lowest values ​​on a surface. The PV value is a measure of surface roughness.

[0080] Optionally, a polishing machine is used to polish the surface of the first conductive layer 11 facing away from the grating portion 30, so that the surface accuracy PV1 of the surface of the first conductive layer 11 facing away from the grating portion 30 is PV1≤15nm, thereby achieving optical-grade flatness. Because the volume shrinks when the first heat-fixing resin undergoes a polymerization reaction to form the first conductive layer 11, the surface of the first conductive layer 11 facing away from the grating portion 30 will be uneven. Therefore, it is necessary to polish the surface of the first conductive layer 11 facing away from the grating portion 30 to achieve optical-grade flatness, thereby giving the fabricated waveguide sheet 100 a better image display effect.

[0081] S405, a second conductive layer 13 is formed by injection molding on the surface of the first conductive layer 11 that is away from the grating portion 30; S406, inject a second thermosetting resin adhesive onto the surface of the second conductive layer 13 opposite to the first conductive layer 11; S407, the second thermosetting resin adhesive is cured to obtain the third conductive layer 15; and For a detailed description of S405 to S407, please refer to the description of the corresponding parts of the above embodiments, which will not be repeated here.

[0082] S408, the surface of the third conductive layer 15 facing away from the second conductive layer 13 is polished so that the surface accuracy PV2 of the surface of the third conductive layer 15 facing away from the second conductive layer 13 is PV2≤15nm.

[0083] Optionally, a polishing machine is used to polish the surface of the third conductive layer 15 facing away from the second conductive layer 13, so that the surface accuracy PV1 of the surface of the third conductive layer 15 facing away from the second conductive layer 13 is PV1≤15nm, thereby achieving optical-grade flatness. Because the volume shrinks when the second thermosetting resin undergoes a polymerization reaction to form the third conductive layer 15, the surface of the third conductive layer 15 facing away from the second conductive layer 13 will be uneven. Therefore, it is necessary to polish the surface of the third conductive layer 15 facing away from the second conductive layer 13 to achieve optical-grade flatness, thereby giving the fabricated optical waveguide 100 better image display performance.

[0084] Please see Figure 9The first molding method is injection molding, and the second molding method is casting molding; the preparation method of the optical waveguide sheet 100 provided in this application embodiment includes: S501, the first conductive layer 11 and the grating portion 30 with an integral structure are obtained by injection molding, and the third conductive layer 15 is obtained; like Figure 10 and Figure 11 As shown, optionally, a thermoplastic resin such as polycarbonate is used, and the first conductive layer 11, the grating portion 30, and the third conductive layer 15, all of which have an integral structure, are formed by injection molding using a first injection mold P and a second injection mold Q. Since the first conductive layer 11 and the second conductive layer 13 obtained by high-pressure injection molding do not experience significant volume shrinkage, neither the first conductive layer 11 nor the third conductive layer 15 requires polishing.

[0085] Polycarbonate has a high refractive index, which allows the optical waveguide 100 to have a large field of view (FOV). Its heat distortion temperature is also high, typically around 135°C, higher than 120°C, thus preventing softening during the casting and curing process to form the second conductive layer 13.

[0086] For a detailed description of the first conductive layer 11, the grating portion 30, and the third conductive layer 15, please refer to the description of the corresponding part of the above embodiment, which will not be repeated here.

[0087] S502, the first conductive layer 11 and the third conductive layer 15 are disposed at intervals in the second mold 100b, and the grating portion 30 is positioned away from the third conductive layer 15; Please see also Figure 12 Optionally, the second mold 100b has a second mold cavity 101b, in which the first conductive layer 11 is installed on one side of the second mold cavity 101b, and the third conductive layer 15 is installed on the side opposite to the first conductive layer 11 in the second mold cavity 101b, so that there is a gap between the first conductive layer 11 and the second conductive layer 13, and at the same time, the first conductive layer 11 is closer to the third conductive layer 15 than the grating portion 30. In other words, the grating portion 30 is farther away from the third conductive layer 15 than the first conductive layer 11.

[0088] Understandably, after the first conductive layer 11 and the third conductive layer 15 are installed, the surface of the first conductive layer 11 facing the third conductive layer 15 is parallel to the surface of the third conductive layer 15 facing the second conductive layer 13.

[0089] Optionally, the width of the gap between the first conductive layer 11 and the third conductive layer 15, i.e., the vertical distance between the surface of the first conductive layer 11 facing the third conductive layer 15 and the surface of the third conductive layer 15 facing the second conductive layer 13, ranges from 0.01 mm to 0.1 mm. In other words, the spacing between the first conductive layer 11 and the third conductive layer 15 is adjusted so that their spacing is equal to the thickness of the second conductive layer 13.

[0090] In some embodiments, the second mold 100b further has a groove 103b, which surrounds the outer periphery of the second mold cavity 101b and communicates with the second mold cavity 101b. In this case, the step of spaced-apart the first conductive layer 11 and the third conductive layer 15 within the second mold 100b includes spaced-apart the first conductive layer 11 and the third conductive layer 15 within the second mold cavity 101b, and ensuring that the gap between the first conductive layer 11 and the third conductive layer 15 communicates with the groove 103b.

[0091] Optionally, the groove 103b is located at the middle position on the outer periphery of the second mold cavity 101b. This allows the gap formed between the first conductive layer 11 and the third conductive layer 15 after they are disposed in the second mold cavity 101b to be better aligned with the groove 103b and communicate with it.

[0092] S503, inject a third thermosetting resin adhesive into the gap between the first conductive layer 11 and the third conductive layer 15; Optionally, a third thermosetting resin adhesive may be filled into the gap between the first conductive layer 11 and the third conductive layer 15.

[0093] Optionally, the third thermosetting resin adhesive may include thermosetting resin monomers and a curing agent. The thermosetting resin monomers include at least one selected from propylene carbonate, allyl diethylene glycol carbonate, acrylonitrile, ethylene glycol dimethacrylate, allyl acrylate, diallyl phthalate, and carbamate. The curing agent includes at least one selected from tert-butyl peroxynedecanoate, isophorone diamine, ethylenediamine, and methylenebicyclohexaneamine.

[0094] Optionally, the third thermosetting resin liquid may also include at least one of a release agent, an antioxidant, etc.

[0095] Optionally, the third thermosetting resin adhesive may further include at least one of titanium dioxide or zirconium dioxide to give the third conductive layer 15 a higher refractive index.

[0096] Optionally, when the second mold 100b also has a groove 103b, the method further includes injecting a third thermosetting resin into the groove 103b. In other words, the third thermosetting resin is injected into both the gap between the first conductive layer 11 and the third conductive layer 15 and into the groove 103b.

[0097] When the third thermosetting resin adhesive undergoes a polymerization reaction and cures, it will shrink in volume. The gap between the first layer and the third layer is small. The third thermosetting resin adhesive is also injected into the groove 103b. When the third thermosetting resin adhesive undergoes a polymerization reaction and cures and shrinks in volume, a certain amount of the third thermosetting resin adhesive can be drawn from the groove 103b by capillary force (that is, the third thermosetting resin adhesive in the groove 103b will flow into the gap between the first conductive layer 11 and the third conductive layer 15 under the action of capillary force). This ensures that the gap between the first conductive layer 11 and the third conductive layer 15 is always filled, and there will be no undesirable phenomena such as incomplete filling or delamination between the first conductive layer 11 and the third conductive layer 15.

[0098] For a detailed description of other aspects of the second thermosetting resin solution, please refer to the description of the first thermoplastic resin in the above embodiments, which will not be repeated here.

[0099] S504, the third thermosetting resin adhesive is cured to obtain the second conductive layer 13.

[0100] Optionally, the third thermosetting resin solution is heated (e.g., to 70°C to 120°C) to cause the thermosetting resin monomers to polymerize with the curing agent, thereby forming a thermosetting resin layer, namely the second conductive layer 13.

[0101] Please see Figure 13 and Figure 14 This application also provides an augmented reality device 500, which includes a projection optical engine 510 and an optical waveguide 100. The projection optical engine 510 is used to project light signals, the light signals including image information; the optical waveguide 100 is disposed on the exit surface of the projection optical engine 510 and is used to transmit the light signals. Understandably, the grating portion 30 of the optical waveguide 100 is disposed away from the projection optical engine 510.

[0102] Optionally, the projection optical engine 510 includes a display 511 and a lens 513. The display 511 is used to emit light signals, and the lens 513 is disposed on the display surface side of the display 511 to modulate the light signals, so that light rays (light signals) emitted from the same pixel on the display 511 at different viewing angles are modulated by the lens 513 and emitted in the form of parallel light, so that the image information in the light signals is at infinity so that it can be viewed by the naked eye. The optical waveguide 100 is disposed on the side of the lens 513 away from the display 511 and is used to transmit the light signals modulated by the lens 513.

[0103] The augmented reality device 500 of this application can be, but is not limited to, near-eye display devices such as augmented reality glasses (AR glasses), augmented reality helmets, and augmented reality masks.

[0104] Optionally, the display 511 can be a microdisplay. The display 511 includes a light-emitting unit, which may include, but is not limited to, at least one of a micro light-emitting diode (Micro LED) chip, a micro organic light-emitting diode (Micro OLED) chip, or a micro liquid crystal display (Micro LCD). Under the same operating power conditions, the brightness of a Micro OLED is typically less than 5000 nits, and the brightness of an LCD is typically less than 15000 nits, while the brightness of a Micro LED can reach 2,000,000 nits, far exceeding the former two. Therefore, compared to Micro OLED displays and Micro LCD displays, when the display 511 is a Micro LED display, its output image has higher brightness. Compared to Micro LCD displays, Micro LED displays are self-emissive light sources, offering better contrast and lower display latency when applied to the augmented reality device 500.

[0105] In some embodiments, the area on the display surface capable of emitting light signals is called the effective light-emitting area, and the diagonal size of the effective light-emitting area of ​​the display 511 ranges from 0.11 inch to 0.15 inch, with an aspect ratio of 4:3. In other embodiments, the diagonal size of the effective light-emitting area of ​​the display 511 ranges from 0.17 inch to 0.21 inch, with an aspect ratio of 16:9.

[0106] Optionally, the color of the light emitted by the display 511 can be, but is not limited to, at least one of red, green, and blue light. In one specific embodiment, the display 511 is a Micro LED that emits green light; in other embodiments, it can also be other monochromatic or polychromatic Micro LEDs.

[0107] In some embodiments, the optical waveguide 100 can also dilate the image information in the light signal emitted from the lens 513 in one or two dimensions to increase the range of eye movement, thereby accommodating a wider range of people.

[0108] In some embodiments, the augmented reality device 500 of this application further includes a carrier 550 for carrying the optical waveguide sheet 100.

[0109] Optionally, the carrier 550 can be, but is not limited to, the frame of augmented reality glasses, the helmet body of an augmented reality helmet, the mask body of an augmented reality mask, etc.

[0110] Alternatively, the optical waveguide 100 may be attached to the carrier 550 by means of adhesive or fasteners.

[0111] In some embodiments, when the augmented reality device 500 is augmented reality glasses, the augmented reality device 500 of this application embodiment further includes a wearing member 530. The wearing member 530 is rotatably connected to the support member 550, and the wearing member 530 is used to hold the wearer (such as a human head or a head prosthesis).

[0112] Optionally, the wearing component 530 includes a first wearing sub-component 531 and a second wearing sub-component 533. The first wearing sub-component 531 is rotatably connected to one end of the carrier 550, and the second wearing sub-component 533 is rotatably connected to the other end of the carrier 550 away from the first wearing sub-component 531. The first wearing sub-component 531 and the second wearing sub-component 533 cooperate to hold the augmented reality device 500 to the wearer. Optionally, the first wearing sub-component 531 and the second wearing sub-component 533 are also used to set up a projection optical engine.

[0113] Optionally, both the first wearing sub-piece 531 and the second wearing sub-piece 533 can be, but are not limited to, temples of an augmented reality device 500 (AR glasses).

[0114] Please see Figure 15The augmented reality device 500 in this embodiment further includes a processor 540 and a memory 560. The processor 540 is electrically connected to the display 511 and is used to control the display 511 to emit light signals with image information, etc. The memory 560 is electrically connected to the processor 540 and is used to store program code required for the processor 540 to run, program code required for controlling the display 511, image information emitted by the display 511, etc.

[0115] Optionally, processor 540 includes one or more general-purpose processors, wherein the general-purpose processor can be any type of device capable of processing electronic instructions, including a central processing unit (CPU), microprocessor, microcontroller, main processor, controller, and ASIC, etc. Processor 540 is used to execute various types of digital storage instructions, such as software or firmware programs stored in memory 560, which enables the computing device to provide a wide range of services.

[0116] Optionally, memory 560 may include volatile memory, such as random access memory (RAM); memory 560 may also include non-volatile memory (NVM), such as read-only memory (ROM), flash memory (FM), hard disk drive (HDD), or solid-state drive (SSD). Memory 560 may also include combinations of the above types of memory.

[0117] It is understood that the augmented reality device 500 in this embodiment is merely one form of the augmented reality device 500 used in the optical waveguide sheet 100, and should not be construed as a limitation on the augmented reality device 500 provided in this application.

[0118] In this application, the terms "embodiment" and "implementation" mean that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The appearance of these phrases in various locations throughout the specification does not necessarily refer to the same embodiment, nor are they independent or alternative embodiments mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this application can be combined with other embodiments. Furthermore, it should be understood that the features, structures, or characteristics described in the various embodiments of this application can be arbitrarily combined to form another embodiment that does not depart from the spirit and scope of the technical solution of this application, provided there is no contradiction between them.

[0119] 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 it. Although this application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. An optical waveguide sheet, characterized in that, include: A light-conducting section, comprising a first conductive layer, a second conductive layer, and a third conductive layer stacked sequentially; the refractive index of the first conductive layer is greater than that of the second conductive layer, and the refractive index of the third conductive layer is greater than that of the first conductive layer; and The grating section includes an optical coupler inlet and an optical coupler outlet, which are spaced apart on the surface of the first conductive layer away from the second conductive layer.

2. The optical waveguide sheet according to claim 1, characterized in that, The first conductive layer, the second conductive layer, the third conductive layer, and the grating section are an integral structure.

3. The optical waveguide sheet according to claim 1, characterized in that, Along the stacking direction of the first conductive layer, the second conductive layer and the third conductive layer, the thickness of the first conductive layer is greater than the thickness of the second conductive layer, and the thickness of the third conductive layer is greater than the thickness of the second conductive layer.

4. The optical waveguide sheet according to claim 3, characterized in that, Along the stacking direction of the first conductive layer, the second conductive layer, and the third conductive layer, the ratio of the thickness h1 of the first conductive layer to the thickness h2 of the second conductive layer, h1 / h2, is in the range of 7:1≤h1 / h2≤10:1; along the stacking direction of the first conductive layer, the second conductive layer, and the third conductive layer, the ratio of the thickness h3 of the third conductive layer to the thickness h2 of the second conductive layer, h3 / h2, is in the range of 10≤h3 / h2≤14:

1.

5. The optical waveguide sheet according to claim 4, characterized in that, Along the stacking direction of the first conductive layer, the second conductive layer and the third conductive layer, the thickness h1 of the first conductive layer is in the range of 0.2mm≤h1≤3mm, the thickness h2 of the second conductive layer is in the range of 0.01mm≤h2≤0.1mm, and the thickness h3 of the third conductive layer is in the range of 0.2mm≤h3≤3mm.

6. The optical waveguide sheet according to claim 4, characterized in that, The optical waveguide sheet satisfies the following relationship: 2(h1+h3)tanθ1=2h3×tanθ2; and θ2≥sin -1 (n2 / n1); Wherein, n1 is the refractive index of the first conductive layer, n2 is the refractive index of the second conductive layer, θ1 is the diffraction angle of light rays perpendicularly incident on the optical waveguide when the optical conductive part is a single layer with a thickness h = h1 + h3 and a refractive index of n1, and the light rays are incident on the optical waveguide sheet; θ2 is the diffraction angle of light rays in the optical waveguide sheet.

7. The optical waveguide sheet according to any one of claims 1 to 6, characterized in that, The first conductive layer and the third conductive layer are both thermosetting resin layers, and the second conductive layer is a thermoplastic resin layer; or, the first conductive layer and the third conductive layer are both thermoplastic resin layers, and the second conductive layer is a thermosetting resin layer.

8. A method for fabricating an optical waveguide sheet, characterized in that, The optical waveguide includes an optical transmission section and a grating section. The optical transmission section includes a first transmission layer, a second transmission layer, and a third transmission layer stacked sequentially. The refractive index of the first transmission layer is greater than that of the second transmission layer, and the refractive index of the third transmission layer is greater than that of the first transmission layer. The grating section is disposed on the surface of the first transmission layer facing away from the second transmission layer. The method includes: The first conductive layer and the grating section are formed using a first molding method; The second conductive layer is formed using a second molding method; and The third conductive layer is formed using a first molding method; wherein the first molding method is injection molding or casting molding, and the second molding method is injection molding or casting molding, and the first molding method is different from the second molding method.

9. The method for preparing an optical waveguide sheet according to claim 8, characterized in that, The first molding method is casting molding, and the second molding method is injection molding. The methods include: A first mold is provided, the first mold including a first sub-mold and a second sub-mold, the first sub-mold and the second sub-mold forming a first mold cavity, the first sub-mold having a grating texture facing the first mold cavity, the grating texture being complementary to the structure of the grating portion; Inject the first thermosetting resin solution into the first mold cavity; The first thermosetting resin adhesive is cured to obtain the first conductive layer and the grating section; A second conductive layer is formed by injection molding on the surface of the first conductive layer that is opposite to the grating portion; A second thermosetting resin adhesive is injected into the surface of the second conductive layer opposite to the first conductive layer; and The second thermosetting resin adhesive is cured to obtain the third conductive layer.

10. The method for preparing the optical waveguide sheet according to claim 9, characterized in that, The step of curing the first thermosetting resin adhesive to obtain the first conductive layer and the grating portion includes: Along the direction of gravity, the first sub-mold is positioned below the second sub-mold, and the first thermosetting resin is cured to obtain the first conductive layer and the grating portion.

11. The method for fabricating the optical waveguide sheet according to claim 9, characterized in that, After curing the first thermosetting resin adhesive to obtain the first conductive layer and the grating portion, and before injection molding the second conductive layer on the surface of the first conductive layer opposite to the grating portion, the method further includes: The surface of the first conductive layer away from the grating portion is polished so that the surface accuracy PV1 of the first conductive layer away from the grating portion is PV1≤15nm; After curing the second thermosetting resin adhesive to obtain the third conductive layer, the method further includes: The surface of the third conductive layer that faces away from the second conductive layer is polished so that the surface accuracy PV2 of the surface of the third conductive layer facing away from the second conductive layer is PV2≤15nm.

12. The method for preparing the optical waveguide sheet according to claim 8, characterized in that, The first molding method is injection molding, and the second molding method is casting molding; the method includes: The first conductive layer and the grating portion, which are integrally structured, are obtained by injection molding, and the third conductive layer is also obtained. The first conductive layer and the third conductive layer are spaced apart in the second mold, and the grating portion is positioned away from the third conductive layer. A third thermosetting resin adhesive is injected into the gap between the first conductive layer and the third conductive layer; The third thermosetting resin adhesive is cured to obtain the second conductive layer.

13. The method for preparing the optical waveguide sheet according to claim 12, characterized in that, The second mold has a communicating second mold cavity and a groove, the groove being disposed around the outer periphery of the second mold cavity, and the step of spaced the first conductive layer and the third conductive layer within the second mold includes: The first conductive layer and the third conductive layer are spaced apart in the second mold cavity, and the gap between the first conductive layer and the third conductive layer is connected to the groove. The step of injecting a third thermosetting resin adhesive between the first conductive layer and the third conductive layer includes: A third thermosetting resin adhesive is injected into the gap between the first conductive layer and the third conductive layer, as well as into the groove.

14. An augmented reality device, characterized in that, include: A projection optical engine for projecting light signals, the light signals including image information; as well as The optical waveguide sheet according to any one of claims 1 to 7, wherein the optical waveguide sheet is used to transmit the optical signal.

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