Optical waveguide structure, preparation method thereof and head-mounted display device

Abstract

The invention discloses an optical waveguide structure, a preparation method thereof and a head-mounted display device, and relates to the technical field of optical waveguides, the optical waveguide structure comprises a polymer substrate and a surface type improvement layer arranged on the polymer substrate, and the hardness of the surface type improvement layer is higher than that of the polymer substrate; the surface type improving layer comprises a grating area, and a grating structure in the grating area is formed by cured imprinting glue; and a non-grating area outside the grating area on the surface type improvement layer comprises an impressing glue layer and a glare improvement layer on the impressing glue layer. According to the invention, the glare effect of the existing optical waveguide structure is suppressed.

Description

Technical Field

[0001] The present application relates to the field of optical waveguide technology, and in particular to an optical waveguide structure and a preparation method thereof, and a head-mounted display device. Background Art

[0002] With the rapid development of augmented reality (AR) technology, diffractive optical waveguides, as the core optical display devices in the AR field, play a vital role.

[0003] Polymer materials (such as resins) have become the substrate options for optical waveguide structures due to their advantages such as light weight, strong impact resistance, and easy processing. However, due to the low hardness and high flexibility of polymer substrates, there are surface problems, which will seriously affect the optical performance of the optical waveguide structure. This will also change the optical path of light propagating in the optical waveguide structure, making the existing optical waveguide structure more prone to glare effects.

[0004] The above contents are only used to assist in understanding the technical solution of the present application and do not constitute an admission that the above contents are prior art. Summary of the invention

[0005] The main purpose of the present application is to provide an optical waveguide structure and a preparation method thereof and a head-mounted display device, aiming to solve the technical problem that the optical waveguide structure has a glare effect due to a polymer substrate.

[0006] To achieve the above-mentioned purpose, the present application proposes an optical waveguide structure comprising: a polymer substrate and a surface shape improvement layer disposed on the polymer substrate, wherein the hardness of the surface shape improvement layer is higher than that of the polymer substrate; The surface shape improvement layer includes a grating area, and the grating structure in the grating area is composed of a cured embossed adhesive; The non-grating area outside the grating area on the surface shape improvement layer includes an embossed adhesive layer and a glare improvement layer on the embossed adhesive layer.

[0007] In one embodiment, the difference between the refractive index of the surface shape improvement layer and the refractive index of the polymer substrate is less than a predetermined refractive index difference.

[0008] In one embodiment, the film thickness of the glare improvement layer and the surface thickness of the surface shape improvement layer are determined according to the geometric shape and refractive index of the polymer substrate, the adhesive layer thickness and refractive index of the embossed adhesive layer, the refractive index of the glare improvement layer and the refractive index of the surface shape improvement layer.

[0009] In one embodiment, the glare improvement layer comprises an anti-reflection film layer on the embossed adhesive layer, and the refractive index of the anti-reflection film layer is smaller than the refractive index of the embossed adhesive layer; or, The glare improvement layer includes at least two anti-reflection film layers on the surface shape improvement layer, and the refractive index of the anti-reflection film layer farthest from the embossed adhesive layer is less than or equal to the refractive index of the embossed adhesive layer.

[0010] In one embodiment, the surface shape improving layer is also disposed on the back side of the polymer substrate.

[0011] In addition, to achieve the above-mentioned purpose, the present application also provides a method for preparing an optical waveguide structure, the method for preparing an optical waveguide structure comprising: After coating the surface shape improvement layer on the polymer substrate, spin coating and evenly coating the surface shape improvement layer with an embossing glue; The hardness of the surface improvement layer is higher than that of the polymer substrate; Imprinting and curing the grating area of ​​the surface shape improvement layer; A glare improvement layer is plated on the non-grating area other than the grating area of ​​the surface shape improvement layer to obtain an optical waveguide structure.

[0012] In one embodiment, before the step of coating the surface improvement layer on the polymer substrate, the process includes: Obtaining the geometric shape and refractive index of the polymer substrate, and the thickness and refractive index of the embossed adhesive layer; Constructing an optical waveguide structure simulation model according to the geometric shape and refractive index of the polymer substrate, the thickness and refractive index of the embossed adhesive layer, the refractive index of the glare improvement layer, and the refractive index of the surface shape improvement layer; Simulating a first optional thickness of the glare improvement layer and a second optional thickness of the surface shape improvement layer based on the optical waveguide structure simulation model to obtain theoretical reflectivities of the optical waveguide structure corresponding to the first optional thickness and the second optional thickness; According to the theoretical reflectivity, the film thickness of the glare improvement layer and the surface thickness of the surface shape improvement layer are selected from the first optional thickness and the second optional thickness.

[0013] In one embodiment, the glare improvement layer comprises an anti-reflection film layer on the embossed adhesive layer, and the refractive index of the anti-reflection film layer is smaller than the refractive index of the embossed adhesive layer; or, The glare improvement layer includes at least two anti-reflection film layers on the surface shape improvement layer, and the refractive index of the anti-reflection film layer farthest from the embossed adhesive layer is less than or equal to the refractive index of the embossed adhesive layer.

[0014] In one embodiment, the method for preparing the optical waveguide structure further includes: A surface improvement layer is plated on the back side of the polymer substrate.

[0015] In addition, to achieve the above objectives, the present application also provides a head-mounted display device, which includes the optical waveguide structure as described in any one of the above items.

[0016] One or more technical solutions proposed in this application have at least the following technical effects: In the present application, the optical waveguide structure includes: a polymer substrate and a surface shape improvement layer arranged on the polymer substrate, the hardness of the surface shape improvement layer is higher than that of the polymer substrate; the surface shape improvement layer includes a grating area, and the grating structure in the grating area is composed of a cured embossed adhesive; the non-grating area outside the grating area on the surface shape improvement layer includes an embossed adhesive layer and a glare improvement layer on the embossed adhesive layer. Therefore, on the one hand, the present application fixes the surface shape of the polymer substrate through the high hardness of the surface shape improvement layer, thereby avoiding the surface shape problem causing the change of the optical path of the light propagating in the optical waveguide structure. On the other hand, on the basis of the stability of the optical path, a glare improvement layer is added to the embossed adhesive layer to reduce the glare effect caused by the high reflectivity brought by the embossed adhesive layer. By combining the two, the present application realizes the suppression of the glare effect of the existing optical waveguide structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 is a schematic diagram of the structure of an optical waveguide; Figure 2 is a schematic structural diagram of an existing optical waveguide structure; Figure 3 A schematic diagram of the structure of an optical waveguide structure provided in an embodiment of the present application; Figure 4 A schematic structural diagram of another optical waveguide structure provided in an embodiment of the present application; Figure 5 A schematic diagram of another optical waveguide structure provided in an embodiment of the present application Figure 6 A schematic diagram of a process flow provided for an embodiment of a method for preparing an optical waveguide structure of the present application; Figure 7 A schematic diagram of a scenario provided for an embodiment of a method for preparing an optical waveguide structure of the present application; Figure 8 A schematic diagram of the surface of the original optical waveguide structure involved in the embodiment of the present application; Fig. 9 A schematic diagram of the reflectivity results of the original optical waveguide structure provided in the embodiment of the present application; Fig.10 A schematic diagram of simulation results of a glare improvement layer and a surface shape improvement layer involved in an embodiment of the present application; Fig.11 A schematic structural diagram of an improved optical waveguide structure according to an embodiment of the present application; Fig.12 for Fig.11 Schematic diagram of the surface of the improved optical waveguide structure; Fig.13 for Fig.11 Schematic diagram of reflectivity results of the improved optical waveguide structure; Fig.14 A schematic diagram of a scenario for determining process parameters of the preparation method involved in an embodiment of the present application.

[0020] The purpose, features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0021] Embodiments of the present disclosure will be described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present disclosure, and are not to be construed as limitations on the present disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present disclosure.

[0022] The features of the terms "first" and "second" in the specification and claims of the present disclosure may explicitly or implicitly include one or more of the features. In the description of the present disclosure, unless otherwise specified, "plurality" means two or more.

[0023] In the description of the present disclosure, it should be understood that the terms "center", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present disclosure.

[0024] In the description of the present disclosure, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0025] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0026] The main solution of the embodiment of the present application is: the optical waveguide structure includes: a polymer substrate and a surface improvement layer arranged on the polymer substrate, the hardness of the surface improvement layer is higher than that of the polymer substrate; the surface improvement layer includes a grating area, and the grating structure in the grating area is composed of a cured embossed adhesive; the non-grating area outside the grating area on the surface improvement layer includes an embossed adhesive layer and a glare improvement layer on the embossed adhesive layer.

[0027] The existing resin has become the substrate option for the optical waveguide structure due to its advantages such as light weight, strong impact resistance and easy processing. However, the polymer substrate has surface problems due to its low hardness and high flexibility, which will seriously affect the optical performance of the optical waveguide structure. This will also change the optical path of the light propagating in the optical waveguide structure. In addition, Figure 1 As shown, Figure 1 The schematic diagram of the structure of the optical waveguide structure involved in this application. According to different design architectures, diffraction optical waveguides are mainly divided into two categories: one-dimensional (1D) architecture and two-dimensional (2D) structure. Although the two are different in structure and application scenarios, their common feature is that the surface contains grating areas and non-grating areas. Figure 2 As shown in the figure, in order to enhance the diffraction effect of the grating and improve the overall efficiency of the waveguide during the nanoimprinting process, an imprinting glue with a refractive index higher than that of the substrate material is usually selected as the material constituting the grating, which also leads to a significant increase in the surface reflectivity of the non-grating area, forming a glare effect. The surface shape of the polymer substrate will change the optical path of the light propagating in the optical waveguide structure, which will make the existing optical waveguide structure more prone to glare effects.

[0028] The present application provides a solution. On the one hand, the high hardness of the surface shape improvement layer is used to fix the surface shape of the polymer substrate, so as to avoid the surface shape problem causing the light path of the light propagating in the optical waveguide structure to be changed. On the other hand, on the basis of the stability of the optical path, a glare improvement layer is added to the embossed adhesive layer to reduce the glare effect caused by the high reflectivity of the embossed adhesive layer. By combining the two, the present application realizes the suppression of the glare effect of the existing optical waveguide structure.

[0029] Based on this, Figure 3 As shown, the optical waveguide structure provided in the embodiment of the present application includes: a polymer substrate and a surface shape improvement layer disposed on the polymer substrate, wherein the hardness of the surface shape improvement layer is higher than that of the polymer substrate; The surface shape improvement layer includes a grating area, and the grating structure in the grating area is composed of a cured embossed adhesive; The non-grating area outside the grating area on the surface shape improvement layer includes an embossed adhesive layer and a glare improvement layer on the embossed adhesive layer.

[0030] In this embodiment, the polymer substrate is a matrix of an optical waveguide structure made of a polymer material, such as polymethyl methacrylate, polystyrene, polycarbonate, poly-4-methylpentene-1, styrene-acrylonitrile copolymer, allyl diglycol dicarbonate, etc. The grating structure in the grating area is composed of a cured embossed adhesive with a specific structure, which is used to achieve light diffraction and guidance, and the non-grating area is the area on the optical waveguide substrate other than the grating area. The embossed adhesive is a heat-sensitive or photosensitive cured adhesive with good light transmittance used in the nanoimprint process. The surface improvement layer is a coating formed by a light-transmitting material with a hardness higher than that of the polymer substrate, and the surface improvement layer can be composed of one or more layers of coatings. The glare improvement layer is a coating formed by an anti-reflective light-transmitting material, and the glare improvement layer can also be composed of one or more layers of coatings.

[0031] In this embodiment, a surface improvement layer can be plated on a polymer substrate by inkjet printing, physical vapor deposition, etc. The hardness of the surface improvement layer is higher than that of the polymer substrate, thereby improving the rigidity of the polymer substrate and reducing the possibility of surface problems. Then, the surface improvement layer is spin-coated with a stamping glue, wherein the hardness of the surface improvement layer is higher than that of the polymer substrate, and the grating area of ​​the surface improvement layer is stamped and cured to obtain the grating area of ​​the optical waveguide structure. However, in the nanoimprint process, in order to enhance the diffraction effect of the grating and improve the overall efficiency of the waveguide, a stamping glue with a refractive index higher than that of the substrate material is usually selected as the material constituting the grating, which also leads to a significant increase in the surface reflectivity of the non-grating area. Therefore, in this embodiment, it is also necessary to plate a glare improvement layer on the non-grating area other than the grating area of ​​the surface improvement layer to obtain an optical waveguide structure. Since the surface shape of the polymer substrate will seriously affect the optical performance of the optical waveguide structure and change the optical path of the light propagating in the optical waveguide structure, the effect of adding a glare improvement layer to the non-grating area alone on the suppression of the glare effect may be greatly reduced due to the surface shape problem of the polymer substrate during the processing. Furthermore, on the basis of the stability of the optical path, this embodiment adds a glare improvement layer on the embossed adhesive layer to reduce the glare effect caused by the high reflectivity brought by the embossed adhesive layer. By combining the two, the present application realizes the suppression of the glare effect of the existing optical waveguide structure.

[0032] In some embodiments, the difference between the refractive index of the surface shape improvement layer and the refractive index of the polymer substrate is less than a predetermined refractive index difference.

[0033] In the present embodiment, the difference between the refractive index of the surface shape improvement layer and the refractive index of the polymer substrate is less than a predetermined refractive index difference, thereby ensuring that the refractive index between the surface shape improvement layer and the polymer substrate is consistent, thereby avoiding the need to readjust the originally designed grating structure due to the change in the refractive index of the substrate of the optical waveguide structure caused by the addition of the surface shape improvement layer.

[0034] In some embodiments, the film thickness of the glare improvement layer and the surface thickness of the surface shape improvement layer are determined according to the geometric shape and refractive index of the polymer substrate, the adhesive layer thickness and refractive index of the embossed adhesive layer, the refractive index of the glare improvement layer and the refractive index of the surface shape improvement layer.

[0035] Since the different geometrical shapes and refractive indexes of the polymer substrate, the adhesive layer thickness and refractive index of the embossed adhesive layer, the film layer thickness and refractive index of the glare improvement layer, and the surface layer thickness and refractive index of the surface shape improvement layer will all have an impact on the reflectivity, and the geometrical shapes and refractive indexes of the polymer substrate, the adhesive layer thickness and refractive index of the embossed adhesive layer, the refractive index of the glare improvement layer, and the refractive index of the surface shape improvement layer are relatively fixed parameters, the present embodiment can determine the film layer thickness of the glare improvement layer and the surface layer thickness of the surface shape improvement layer according to the geometrical shapes and refractive indexes of the polymer substrate, the adhesive layer thickness and refractive index of the embossed adhesive layer, the refractive index of the glare improvement layer, and the refractive index of the surface shape improvement layer. Exemplarily, this embodiment can obtain the geometric shape and refractive index of the polymer substrate, and the thickness and refractive index of the embossed adhesive layer; construct an optical waveguide structure simulation model according to the geometric shape and refractive index of the polymer substrate, the thickness and refractive index of the embossed adhesive layer, the refractive index of the glare improvement layer, and the refractive index of the surface shape improvement layer; simulate the first optional thickness of the glare improvement layer and the second optional thickness of the surface shape improvement layer based on the optical waveguide structure simulation model to obtain the theoretical reflectivity of the optical waveguide structure corresponding to the first optional thickness and the second optional thickness; select the film thickness of the glare improvement layer and the surface thickness of the surface shape improvement layer from the first optional thickness and the second optional thickness according to the theoretical reflectivity. In this way, the film thickness of the glare improvement layer and the surface thickness of the surface shape improvement layer can be obtained when the theoretical reflectivity is the lowest, which helps to further reduce the reflectivity of the optical waveguide structure.

[0036] In one embodiment, the glare improvement layer comprises an anti-reflection film layer on the embossed adhesive layer, and the refractive index of the anti-reflection film layer is smaller than the refractive index of the embossed adhesive layer; or, The glare improvement layer includes at least two anti-reflection film layers on the surface shape improvement layer, and the refractive index of the anti-reflection film layer farthest from the embossed adhesive layer is less than or equal to the refractive index of the embossed adhesive layer.

[0037] In this embodiment, the glare improvement layer includes an anti-reflection film layer on the embossed adhesive layer, and the refractive index of the anti-reflection film layer is less than that of the embossed adhesive layer. It can be understood that the refractive index of the anti-reflection film layer needs to be greater than that of air. Thus, the anti-reflection film layer is used as a refractive index transition between the embossed adhesive layer and the air to reduce the reflection caused by the sudden change of the refractive index. Figure 4 As shown, in this embodiment, the glare improvement layer may also include at least two anti-reflection film layers on the embossed adhesive layer, and the refractive index of the anti-reflection film layer farthest from the embossed adhesive layer is less than or equal to the refractive index of the embossed adhesive layer. It can be understood that Figure 4Only two anti-reflection film layers are shown in the figure. In fact, the glare improvement layer may include more anti-reflection film layers. As an example, at least two anti-reflection film layers may be multiple coating layers with a first refractive index and a refractive index interlaced, wherein the first refractive index is greater than the refractive index and the refractive index is less than or equal to the refractive index of the embossed adhesive layer. The multiple coating layers with a first refractive index and a refractive index interlaced utilize the interference effect. By alternating the arrangement of coating layers with different refractive indices, some reflected light waves cancel each other out to achieve the effect of reducing the reflectivity. As another example, at least two anti-reflection film layers may be multiple coating layers with continuously reduced refractive indices, wherein the refractive index of the anti-reflection film layer gradually decreases from the anti-reflection film layer closest to the embossed adhesive layer to the anti-reflection film layer farthest from the embossed adhesive layer (i.e., in the direction from the embossed adhesive layer to the air). Multiple coating layers with continuously reduced refractive indices can smoothly transition the refractive index difference between the embossed adhesive layer and the air, reduce reflection at the interface, and also achieve the effect of reducing the reflectivity.

[0038] In some embodiments, the surface shape improving layer is also disposed on the back side of the polymer substrate.

[0039] like Figure 5 As shown, in this embodiment, the surface shape improvement layer is also arranged on the back side of the polymer substrate, thereby further improving the rigidity of the polymer substrate and preventing the polymer substrate from deforming in a direction away from the surface shape improvement layer.

[0040] Based on this, the present application embodiment provides a method for preparing an optical waveguide structure, referring to Figure 6 , Figure 6 FIG. 1 is a schematic flow chart of a first embodiment of a method for preparing an optical waveguide structure of the present application.

[0041] In this embodiment, the method for preparing the optical waveguide structure includes steps S10 to S30: Step S10, after coating the surface shape improvement layer on the polymer substrate, spin coating the surface shape improvement layer with an embossing glue; Step S20, embossing and curing the grating area of ​​the surface shape improvement layer; Step S30, coating the non-grating area of ​​the surface shape improvement layer with a glare improvement layer outside the grating area to obtain an optical waveguide structure.

[0042] like Figure 7As shown, in this embodiment, a surface improvement layer can be plated on a polymer substrate by inkjet printing, physical vapor deposition, etc. The hardness of the surface improvement layer is higher than that of the polymer substrate, thereby improving the rigidity of the polymer substrate and reducing the possibility of surface problems. Furthermore, in this embodiment, the surface improvement layer can be spin-coated with a printed glue by a spin coating operation, so that a uniform printed glue film is formed on the surface improvement layer. Furthermore, in this embodiment, the printed glue in the grating area of ​​the surface improvement layer is embossed by a master template corresponding to the grating structure in the grating area of ​​the surface improvement layer, so that the grating in the grating area is formed and cured. Since the spin coating method is adopted, there is a printed glue layer on the surface of the non-grating area of ​​the optical waveguide substrate. Furthermore, in this embodiment, a glare improvement layer can be plated on the non-grating area of ​​the surface improvement layer except the grating area to obtain an optical waveguide structure, wherein the glare improvement layer can be used according to different materials. Different coating processes, such as inkjet printing or physical vapor deposition, are selected to reduce the reflectivity of the non-grating area.

[0043] In a feasible implementation manner, before the step of coating the surface improvement layer on the polymer substrate in step S10, steps A11 to A14 may be included: Step A11, obtaining the geometric shape and refractive index of the polymer substrate, and the thickness and refractive index of the embossed adhesive layer; Step A12, constructing an optical waveguide structure simulation model according to the geometric shape and refractive index of the polymer substrate, the thickness and refractive index of the embossed adhesive layer, the refractive index of the glare improvement layer, and the refractive index of the surface shape improvement layer; Step A13, simulating the first optional thickness of the glare improvement layer and the second optional thickness of the surface shape improvement layer based on the optical waveguide structure simulation model to obtain theoretical reflectivities of the optical waveguide structure corresponding to the first optional thickness and the second optional thickness; Step A14: selecting the film thickness of the glare improvement layer and the surface thickness of the surface shape improvement layer from the first optional thickness and the second optional thickness according to the theoretical reflectivity.

[0044] In this embodiment, the geometric shape and refractive index of the polymer substrate, as well as the thickness and refractive index of the embossed adhesive layer, can be obtained, and then according to the geometric shape and refractive index of the polymer substrate, the thickness and refractive index of the embossed adhesive layer, the refractive index of the glare improvement layer, and the refractive index of the surface improvement layer, an optical waveguide structure simulation model is constructed, and the optical waveguide structure simulation model is used to simulate the process of light entering this optical waveguide structure. Then, based on the optical waveguide structure simulation model, the first optional thickness of the glare improvement layer and the second optional thickness of the surface improvement layer can be simulated to obtain the theoretical reflectivity of the optical waveguide structure corresponding to the first optional thickness and the second optional thickness. Then, according to the theoretical reflectivity, the film thickness of the glare improvement layer and the surface thickness of the surface improvement layer are selected from the first optional thickness and the second optional thickness. Exemplarily, the first optional thickness corresponding to the minimum value of the theoretical reflectivity can be selected as the film thickness of the glare improvement layer, and the second optional thickness corresponding to the minimum value of the theoretical reflectivity can be selected as the surface thickness of the surface improvement layer. As a specific example, this example uses a common original optical waveguide structure, which includes an optical waveguide substrate with a refractive index of 1.5, and an embossed adhesive with a refractive index of 1.9 and a thickness of 0.3 microns on the optical waveguide substrate. Figure 8 , Figure 8 This is a schematic diagram of the surface shape of the original optical waveguide structure. The color depth represents the relative height. It can be seen from the figure that the surface shape cannot be fully measured, and the measured peak-to-valley value (i.e. the height difference between the highest point and the lowest point) reaches 43.8um. Fig. 9 , Fig. 9 The horizontal axis of the left graph is the incident angle, the vertical axis is the wavelength, and the color depth is the reflectivity. Fig. 9 The right graph in the middle describes the average reflectivity of the solid surface under a vertical incident angle. The horizontal axis of the right graph is wavelength and the vertical axis is reflectivity. In this embodiment, a light-transmitting material with a harder hardness than the polymer substrate is selected as the surface improvement layer, such as SiO2, and a light-transmitting material with a lower refractive index than the embossed adhesive layer is selected as the glare improvement layer, such as a light-transmitting material with a refractive index of 1.4. Fig.10 As shown, after simulation, Fig.10 It is a simulation result diagram of the optical waveguide structure simulation model. Fig.10 The horizontal axis and the vertical axis are the first optional thickness of the glare improvement layer and the second optional thickness of the surface shape improvement layer, and the vertical axis is the theoretical reflectivity. In order to ensure the surface shape improvement effect of the surface shape improvement layer on the polymer substrate, the thickness of SiO2 needs to be greater than 0.1um. Therefore, when the theoretical reflectivity in the figure is the smallest, Fig.11 As shown, the surface layer thickness of the surface shape improvement layer SiO2 is 0.15um, and the film thickness of the glare improvement layer with a refractive index of 1.4 is 0.1um. Fig.12for Fig.11 Schematic diagram of the surface shape of the optical waveguide structure. It can be seen from the figure that the optical waveguide structure can measure the complete surface shape, and the measured peak-to-valley value is 24.2um. Fig.13 for Fig.11 Schematic diagram of the reflectivity results of the optical waveguide structure, compared with the 6%-16% level of the original optical waveguide structure, Fig.11 The reflectivity of the optical waveguide structure has been reduced to 2%-6%.

[0045] In a feasible implementation manner, the glare improvement layer comprises an anti-reflection film layer on the embossed adhesive layer, and the refractive index of the anti-reflection film layer is smaller than the refractive index of the embossed adhesive layer; or, The glare improvement layer includes at least two anti-reflection film layers on the surface shape improvement layer, and the refractive index of the anti-reflection film layer farthest from the embossed adhesive layer is less than or equal to the refractive index of the embossed adhesive layer.

[0046] In this embodiment, the glare improvement layer includes an anti-reflection film layer on the embossed adhesive layer, and the refractive index of the anti-reflection film layer is less than the refractive index of the embossed adhesive layer. It can be understood that the refractive index of the anti-reflection film layer needs to be greater than the refractive index of air. Thus, this anti-reflection film layer is used as a refractive index transition between the embossed adhesive layer and the air to reduce the reflection caused by the sudden change of the refractive index. In this embodiment, the glare improvement layer may also include at least two anti-reflection film layers on the embossed adhesive layer, and the refractive index of the anti-reflection film layer farthest from the embossed adhesive layer is less than or equal to the refractive index of the embossed adhesive layer. As an example, at least two anti-reflection film layers may be a plurality of coating layers with a first refractive index and a refractive index interlaced, wherein the first refractive index is greater than the refractive index, and the refractive index is less than or equal to the refractive index of the embossed adhesive layer. The plurality of coating layers with a first refractive index and a refractive index interlaced utilize the interference effect, and the alternating arrangement of coating layers with different refractive indices makes some reflected light waves cancel each other out to achieve the effect of reducing the reflectivity. As another example, at least two anti-reflection film layers may be multiple coating layers that continuously reduce the refractive index, wherein the refractive index of the anti-reflection film layer gradually decreases from the anti-reflection film layer closest to the embossed adhesive layer to the anti-reflection film layer farthest from the embossed adhesive layer (i.e., in the direction from the embossed adhesive layer to the air). Multiple coating layers that continuously reduce the refractive index can smoothly transition the refractive index difference between the embossed adhesive layer and the air, reduce reflection at the interface, and also achieve the effect of reducing the reflectivity.

[0047] In a feasible implementation manner, the method for preparing the optical waveguide structure further includes: A surface improvement layer is plated on the back side of the polymer substrate.

[0048] In this embodiment, the surface shape improving layer is also arranged on the back side of the polymer substrate, thereby further improving the rigidity of the polymer substrate and preventing the polymer substrate from deforming in a direction away from the surface shape improving layer.

[0049] As an optional embodiment of the present application, see Fig.14 , the selection of specific process parameters in the preparation method of the optical waveguide structure in the embodiment of the present application can be determined in the following manner. In this embodiment, the surface shape of the original optical waveguide structure to be improved and the reflectivity of the non-grating area can be tested to obtain the peak-to-valley value of the original optical waveguide structure and the reflectivity of the non-grating area. It is determined whether the peak-to-valley value is greater than a predetermined peak-to-valley threshold (such as 30um, 35um, etc.) to determine whether the original optical waveguide structure needs to be improved in surface shape, and it is determined whether the reflectivity is greater than a predetermined reflection threshold (such as 4%, 5%, 6%, etc.) to determine whether the original optical waveguide structure needs to suppress the glare effect. In the case of needing to improve the surface shape and glare, a film material that meets the requirements for the hardness of the surface shape improvement layer and the refractive index of the glare improvement layer is selected from the material library, and then a light waveguide structure simulation model is constructed according to the geometric shape and refractive index of the polymer substrate, the thickness and refractive index of the embossed adhesive layer, the refractive index of the glare improvement layer, and the refractive index of the surface shape improvement layer; based on the light waveguide structure simulation model, the first optional thickness of the glare improvement layer and the second optional thickness of the surface shape improvement layer are simulated to obtain the theoretical reflectivity of the light waveguide structure corresponding to the first optional thickness and the second optional thickness. Then, according to the theoretical reflectivity, the film thickness of the glare improvement layer and the surface thickness of the surface shape improvement layer are selected from the first optional thickness and the second optional thickness. And according to the different processes used for coating the film materials of the glare improvement layer and the surface shape improvement layer, different coating processes (such as inkjet printing and physical vapor deposition) are matched accordingly. The main body improvement scheme, the film layer materials and thicknesses of the glare improvement layer and the surface shape improvement layer, and the adopted coating process are used as specific process parameters in the preparation method of the optical waveguide structure.

[0050] In addition, an embodiment of the present application further provides a head-mounted display device, the head-mounted display device comprising the optical waveguide structure as described above. Exemplarily, the head-mounted display device is a device with optical waveguide function requirements, such as AR glasses, AR helmets, etc.

[0051] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present application.

Claims

1. An optical waveguide structure, characterized in that: The optical waveguide structure comprises: a polymer substrate and a surface shape improvement layer arranged on the polymer substrate, wherein the hardness of the surface shape improvement layer is higher than that of the polymer substrate; The surface shape improvement layer includes a grating area, and the grating structure in the grating area is composed of a cured embossed adhesive; The non-grating area outside the grating area on the surface shape improvement layer includes an embossed adhesive layer and a glare improvement layer on the embossed adhesive layer.

2. The optical waveguide structure according to claim 1, wherein: The difference between the refractive index of the surface shape improvement layer and the refractive index of the polymer substrate is less than a predetermined refractive index difference.

3. The optical waveguide structure according to claim 1, wherein: The film thickness of the glare improvement layer and the surface thickness of the surface shape improvement layer are determined according to the geometric shape and refractive index of the polymer substrate, the adhesive layer thickness and refractive index of the embossed adhesive layer, the refractive index of the glare improvement layer and the refractive index of the surface shape improvement layer.

4. The optical waveguide structure according to claim 3, characterized in that: The glare improvement layer comprises an anti-reflection film layer on the embossed adhesive layer, and the refractive index of the anti-reflection film layer is smaller than the refractive index of the embossed adhesive layer; or The glare improvement layer includes at least two anti-reflection film layers on the surface shape improvement layer, and the refractive index of the anti-reflection film layer farthest from the embossed adhesive layer is less than or equal to the refractive index of the embossed adhesive layer.

5. The optical waveguide structure according to claim 1, wherein: The surface shape improvement layer is also arranged on the back side of the polymer substrate.

6. A method for preparing an optical waveguide structure, characterized in that: The method for preparing the optical waveguide structure comprises: After coating a surface shape improvement layer on a polymer substrate, the surface shape improvement layer is subjected to spin coating and even coating of an embossing glue; The hardness of the surface improvement layer is higher than that of the polymer substrate; Imprinting and curing the grating area of ​​the surface shape improvement layer; A glare improvement layer is plated on the non-grating area other than the grating area of ​​the surface shape improvement layer to obtain an optical waveguide structure.

7. The method for preparing an optical waveguide structure according to claim 6, characterized in that: Before the step of coating the surface improvement layer on the polymer substrate, the method comprises: Obtaining the geometric shape and refractive index of the polymer substrate, and the thickness and refractive index of the embossed adhesive layer; Constructing an optical waveguide structure simulation model according to the geometric shape and refractive index of the polymer substrate, the thickness and refractive index of the embossed adhesive layer, the refractive index of the glare improvement layer, and the refractive index of the surface shape improvement layer; Simulating a first optional thickness of the glare improvement layer and a second optional thickness of the surface shape improvement layer based on the optical waveguide structure simulation model to obtain theoretical reflectivities of the optical waveguide structure corresponding to the first optional thickness and the second optional thickness; According to the theoretical reflectivity, the film thickness of the glare improvement layer and the surface thickness of the surface shape improvement layer are selected from the first optional thickness and the second optional thickness.

8. The method for preparing an optical waveguide structure according to claim 6, wherein: The glare improvement layer comprises an anti-reflection film layer on the embossed adhesive layer, and the refractive index of the anti-reflection film layer is smaller than the refractive index of the embossed adhesive layer; or The glare improvement layer includes at least two anti-reflection film layers on the surface shape improvement layer, and the refractive index of the anti-reflection film layer farthest from the embossed adhesive layer is less than or equal to the refractive index of the embossed adhesive layer.

9. The method for preparing an optical waveguide structure according to claim 6, wherein: The method for preparing the optical waveguide structure further comprises: A surface improvement layer is plated on the back side of the polymer substrate.

10. A head mounted display device, characterized in that: The head mounted display device comprises the optical waveguide structure according to any one of claims 1 to 5.

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