Optical transmission device and head-mounted display device

Abstract

The embodiment of the invention provides an optical transmission device and head-mounted display equipment. The light transmission device comprises a first substrate, a second substrate, a light input element and a light output element, the second substrate is arranged on one side of the first substrate, and the second substrate at least partially covers the first substrate; the light input element and the light output element are arranged on the first substrate; one part of light coupled into the first substrate through the light input element is transmitted to the light output element in a total reflection mode in the first substrate and then is emitted, and the other part of the light enters the second substrate, is transmitted back to the first substrate for multiple times in a total reflection mode and finally is transmitted to the light output element and then is emitted. According to the optical scheme provided by the embodiment of the invention, the optical efficiency of the optical transmission device and the uniformity of coupled light can be improved.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of optical imaging technology. More specifically, embodiments of the present application relate to an optical transmission device and a head-mounted display device. Background Art

[0002] Currently, optical waveguides are one of the mainstream technical solutions for realizing augmented reality, and light is conducted without loss based on the total internal reflection of a transparent substrate. In an optical waveguide, for light rays with different initial incident angles, the angle differences during total internal reflection propagation in the optical waveguide sheet are relatively large, which is particularly obvious for large FOV waveguide sheets.

[0003] Due to the large differences in the propagation angles of each light ray, the spatial position changes in the waveguide plane during a single total internal reflection in the waveguide sheet are large. Therefore, during the process from the light ray being coupled into the waveguide to being coupled out of the waveguide and entering the human eye, the number of times of total internal reflection in the waveguide sheet and the number of times of effective diffraction with the output grating vary greatly for light rays with different angles. Fewer total internal reflection / diffraction times will result in relatively low utilization efficiency of the corresponding light rays, thereby affecting the overall image transmission efficiency of the waveguide. At the same time, the excessive efficiency difference between different light rays will directly lead to poor uniformity of the image transmitted by the waveguide into the eye. Summary of the Invention

[0004] The purpose of the present application is to provide a new technical solution for an optical transmission device and a head-mounted display device.

[0005] According to a first aspect of the present application, there is provided an optical transmission device, the optical transmission device comprising:

[0006] A first substrate;

[0007] A second substrate, the second substrate being disposed on one side of the first substrate, and the second substrate at least partially covering the first substrate;

[0008] An optical input element and an optical output element, disposed on the first substrate;

[0009] Light rays coupled into the first substrate through the optical input element, a part of which is totally internally reflected and propagated in the first substrate to the optical output element and then exits, and another part enters the second substrate for total internal reflection propagation and is transmitted back to the first substrate multiple times, and finally propagates to the optical output element and then exits.

[0010] Optionally, the refractive indices of the first substrate and the second substrate are different.

[0011] Optionally, the thickness of the second substrate is 10um - 500um.

[0012] Optionally, a transmissive-reflective separation layer is disposed between the first substrate and the second substrate.

[0013] Optionally, the transmissive-reflective separation layer is disposed in a local area on the surface of the first substrate close to the second substrate, and is located on a path of light propagating from the first substrate to the second substrate.

[0014] Optionally, the second substrate covers the transmissive-reflective separation layer, and a size of the second substrate matches a size of the transmissive-reflective separation layer.

[0015] Optionally, the second substrate covers the transmissive-reflective separation layer, and the transmissive-reflective separation layer forms a first hollow region at an end close to where light is emitted from the first substrate toward the second substrate.

[0016] Optionally, a second hollow area is formed in the transmissive-reflective separation layer near the light propagation end of the second substrate.

[0017] Optionally, the transflective separation layer includes at least one layer of semi-reflective and semi-transmissive membrane.

[0018] Optionally, an anti-reflection film is provided at a portion of the position between the first substrate and the second substrate;

[0019] The anti-reflection film is located on a path of light propagating from the first substrate to the second substrate.

[0020] Optionally, the anti-reflection film is located between the light transmission end of the second substrate and the first substrate.

[0021] Optionally, the optical transmission device further includes a third substrate and a fourth substrate, and the third substrate and the fourth substrate are sequentially arranged on a side of the second substrate away from the first substrate;

[0022] An anti-reflection film is disposed at a portion between the first substrate and the second substrate, and a transmissive-reflection separation layer and an anti-reflection film are disposed at a portion between the second substrate and the third substrate, respectively.

[0023] Optionally, between the first substrate and the second substrate:

[0024] An anti-reflection film is provided at a position where light is emitted from the first substrate to other substrates and at a position corresponding to a light transmission end of the second substrate; and

[0025] A transmissive-reflective separation layer and an anti-reflective film are disposed between the second substrate and the third substrate, wherein the transmissive-reflective separation layer is close to a position where light is emitted from the second substrate toward the third substrate.

[0026] Optionally, the light input element and the light output element are located on a surface of the first substrate facing away from the second substrate;

[0027] Or,

[0028] The optical input element is located on one side surface of the first substrate close to the second substrate, and the optical output element is located on the other side surface of the first substrate away from the second substrate.

[0029] Optionally, the optical input element and the optical output element are diffractive optical elements.

[0030] According to a second aspect of the present application, there is provided a head-mounted display device, including:

[0031] A housing; and

[0032] The optical transmission device as described in the first aspect.

[0033] One beneficial effect of the embodiments of the present application is:

[0034] The embodiments of the present application provide an optical transmission device. By adding an additional second substrate at an appropriate position on one side of the first substrate, this design can effectively increase the total internal reflection of light and increase the number of diffractive coupling-out times of light at the position of the optical output element, that is, it can increase the density of the coupled-out light at the coupled-out position of the optical transmission device, thereby improving the optical efficiency of the optical transmission structure and the uniformity of the imaging picture.

[0035] Through the following detailed description of the exemplary embodiments of the present specification with reference to the accompanying drawings, other features and advantages of the present specification will become clear. Description of the Drawings

[0036] The drawings incorporated in and constituting a part of this specification illustrate embodiments of the present specification and, together with the description, are used to explain the principles of the present specification.

[0037] Figure 1 One of the side cutaway views of the optical transmission device provided by the embodiments of the present application;

[0038] Figure 2 Another side cutaway view of the optical transmission device provided by the embodiments of the present application;

[0039] Figure 3 A third side cutaway view of the optical transmission device provided by the embodiments of the present application;

[0040] Figure 4 A fourth side cutaway view of the optical transmission device provided by the embodiments of the present application;

[0041] Figure 5 A fifth side cutaway view of the optical transmission device provided by the embodiments of the present application;

[0042] Figure 6 The sixth side cut-away view of the optical transmission device provided by the embodiment of the present application;

[0043] Figure 7 The seventh side cut-away view of the optical transmission device provided by the embodiment of the present application;

[0044] Figure 8 The eighth side cut-away view of the optical transmission device provided by the embodiment of the present application.

[0045] Explanation of reference numerals:

[0046] 11. First substrate; 12. Second substrate; 13. Third substrate; 14. Fourth substrate; 01. Human eye; 20. Light input element; 30. Light output element; 40. Transparent and reflective separation layer; 50. Anti-reflection film. Detailed implementation manners

[0047] Now, various exemplary embodiments of the present application will be described in detail with reference to the accompanying drawings. It should be noted that: unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0048] The following description of at least one exemplary embodiment is merely illustrative and in no way restrictive of the present application or its application or use.

[0049] Technologies and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies and devices should be regarded as part of the specification.

[0050] In all the examples shown and discussed herein, any specific value should be construed as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments may have different values.

[0051] It should be noted that: similar reference numerals and letters denote similar items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0052] Next, with reference to the accompanying drawings, the optical transmission device and the head-mounted display device provided by the embodiments of the present application will be described in detail.

[0053] According to one aspect of the embodiments of the present application, an optical transmission device is provided. The optical transmission device is, for example, an optical waveguide element, which is one of the mainstream technical solutions for realizing augmented reality at present.

[0054] The embodiments of the present application provide an optical transmission device. Refer to Figure 1 and Figure 2, the optical transmission device includes: a first substrate 11, a second substrate 12, and an optical input element 20 and an optical output element 30. Among them, the second substrate 12 is disposed on one side of the first substrate 11, and the second substrate 12 at least partially covers the first substrate 11. The optical input element 20 and the optical output element 30 are disposed on the first substrate 11. In view of this, for the light rays coupled into the first substrate 11 by the optical input element 20, a part of them are totally reflected in the first substrate 11 and propagated to the optical output element 30 and then emitted, and another part are incident into the second substrate 12 and totally reflected and propagated and transmitted back to the first substrate 11 multiple times, and finally propagated to the optical output element 30 and then emitted.

[0055] According to the optical transmission device provided by the embodiment of the present application, by adding an additional second substrate 12 at an appropriate position on one side of the first substrate 11, this design can effectively increase the total reflection of light rays and increase the number of diffraction coupling and output of light rays at the position of the optical output element 30, that is, it can increase the density of the output light rays at the output position of the optical transmission device, so as to improve the optical efficiency of the optical transmission structure and the uniformity of the imaging picture.

[0056] Among them, the thickness of the second substrate 12 can be designed to be relatively thin. For example, the thickness of the second substrate 12 can be designed to be less than the thickness of the first substrate 11, which is beneficial to reducing the weight and can improve the wearing comfort of the user.

[0057] In one example, see Figure 2 , the planar size of the second substrate 12 can be the same as the planar size of the first substrate 11. In view of this, the second substrate 12 can completely cover the first substrate 11. This way can reduce the process difficulty of the optical transmission device.

[0058] In one example, see Figure 1 , the planar size of the second substrate 12 can also be smaller than the planar size of the first substrate 11. At this time, the second substrate 12 is only additionally provided at an appropriate position on one side of the first substrate 11. This design can reduce the production cost on the premise of ensuring the imaging quality, and at the same time can also reduce the weight of the entire optical output device and improve the wearing comfort of the user.

[0059] Among them, the second substrate 12 can be formed on the surface of one side of the first substrate 11, for example, by coating, spin coating layer or laminating an additional waveguide substrate.

[0060] In the optical transmission device provided by the embodiment of the present application, the light rays for forming a virtual image can be received by the optical input element 20 first and then coupled into the first substrate 11, and total reflection propagation can occur in the first substrate 11 and the second substrate 12 respectively. Moreover, the light rays undergoing total reflection in the second substrate 12 can also be transmitted back into the first substrate 11 multiple times. In view of this, in the optical transmission device, the number of times of total reflection and diffractive coupling out of the light rays is significantly increased, which is very beneficial for improving the optical efficiency and the uniformity of the coupled-out light rays.

[0061] In some examples of the present application, the refractive indices of the first substrate 11 and the second substrate 12 are different.

[0062] When the second substrate 12 is stacked on the first substrate 11, the refractive indices of the first substrate 11 and the second substrate 12 can be designed to be different. This is because: when the refractive indices of the two layers are different, partial transmission and partial reflection will occur at the interface between the first substrate 11 and the second substrate 12, so that the light rays can be transmitted from the first substrate 11 to the second substrate 12.

[0063] Of course, the first substrate 11 and the second substrate 12 can also have the same refractive index. At this time, a certain air gap can be designed between the first substrate 11 and the second substrate 12.

[0064] In some examples of the present application, the thickness of the second substrate 12 is 10um to 500um.

[0065] In the optical output device provided by the embodiment of the present application, the thickness of the second substrate 12 should not be designed to be too thick. For example, it can be designed to be 10um to 500um. By restricting the thickness range of the second substrate 12, the thickness of the entire optical transmission device can be controlled, so that without increasing the weight and production cost of the entire optical transmission device too much while ensuring the optical imaging performance.

[0066] In some examples of the present application, referring to Figures 3 to 5 , a transmissive-reflective separation layer 40 is provided between the first substrate 11 and the second substrate 12.

[0067] The transmissive-reflective separation layer 40 can, for example, transmit a part of the light rays and reflect a part of the light rays at the same time. In this way, part of the light rays coupled into the first substrate 11 can still be incident on the second substrate 12 after encountering the transmissive-reflective separation layer 40, and the light rays entering the second substrate 12 can propagate by total reflection in the second substrate 12 and be transmitted back into the first substrate 11 multiple times.

[0068] It should be noted that after introducing the transmissive-reflective separation layer 40 between the first substrate 11 and the second substrate 12, the refractive indices of the first substrate 11 and the second substrate 12 may be the same or different.

[0069] Among them, the transmissive-reflective separation layer 40 may be a single-layer semi-transmissive semi-reflective film. Of course, the transmissive-reflective separation layer 40 may also be a customized semi-transmissive semi-reflective film formed by multiple film materials.

[0070] According to actual requirements, the transmittance and reflection efficiency of the transmissive-reflective separation layer 40 are optional.

[0071] For example, the transmittance and reflectivity of the transmissive-reflective separation layer 40 may vary with the wavelength and the angle of the incident light.

[0072] In some examples of the present application, referring to Figures 3 to 5 , the transmissive-reflective separation layer 40 is disposed in a local area on the surface of the first substrate 11 close to the second substrate 12 and is located on the path of the light propagating from the first substrate 11 to the second substrate 12.

[0073] The transmissive-reflective separation layer 40 is disposed on the surface of the first substrate 11 close to the second substrate 12 so that the transmissive-reflective separation layer 40 can be located on the optical path between the first substrate 11 and the second substrate 12. However, it should be noted that the transmissive-reflective separation layer 40 does not cover the entire first substrate 11 but is located in a local area, that is, the size of the transmissive-reflective separation layer 40 should not exceed the size of the second substrate 12.

[0074] The main light ray incident on the second substrate 12 through the first substrate 11 can be transmitted into the second substrate 12 through the action of the transmissive-reflective separation layer 40, and then undergoes total reflection propagation in the second substrate 12. During the total reflection propagation, multiple transmissions will occur, and the transmitted light rays can return to the first substrate 11 for propagation to increase the number of light rays.

[0075] In some examples of the present application, referring to Figure 3 , the second substrate 12 covers the transmissive-reflective separation layer 40, and the size of the second substrate 12 matches the size of the transmissive-reflective separation layer 40.

[0076] Specifically, a transmissive-reflective separation layer 40 (the reflectivity and transmittance of the transmissive-reflective separation layer 40 are optional) is added locally on a surface of the first substrate 11. At the same time, an additional waveguide total reflection propagation layer with the same or different refractive index as the first substrate 11 and a relatively thin thickness, that is, the second substrate 12 (the thickness of the second substrate 12 can be between 10 um and 500 um), is additionally introduced on the top of the transmissive-reflective separation layer 40. The second substrate 12 can be realized by means such as coating, glue application, or thin-layer glass lamination.

[0077] See Figure 3 , after the incident light at a large angle is introduced into the second substrate 12, it will perform total reflection propagation with a small step size, and at the same time, partially transmit back to the first substrate 11 multiple times, and can undergo coupling diffraction at the light output element 30 together with the light that performs total reflection propagation in the first substrate 11, improving the overall efficiency and picture uniformity.

[0078] It should be noted that the position interval between two adjacent total reflections occurring in the first substrate 11 or the second substrate 12 is called the step size.

[0079] In some examples of the present application, see Figure 4 and Figure 5 , the second substrate 12 covers the transmissive-reflective separation layer 40, and the transmissive-reflective separation layer 40 forms a first hollowed-out area at one end close to the light exiting from the first substrate 11 to the second substrate 12.

[0080] See Figure 4 and Figure 5 As shown, at the front end position of the second substrate 12, the transmissive-reflective separation layer 40 can be selectively removed or not added consciously, which can further improve the uniformity of the distribution of light energy between the light reflection paths. This is because the main light incident from the first substrate 11 to the second substrate 12 can first not pass through the transmissive-reflective separation layer 40, but directly transmit into the relatively thin second substrate 12 on the top, and then perform multiple total reflections (with a small step size) in the second substrate 12, further improving the efficiency and uniformity.

[0081] It should be noted that Figure 4 The difference between Figure 5 and Figure 4 is that in Figure 5 , the second substrate 12 only covers a part of the first substrate 11, while in

[0082] , the second substrate 12 covers the entire first substrate 11.

[0082] Furthermore, see Figure 4 and Figure 5 , the transmissive-reflective separation layer 40 forms a second hollowed-out area at a position close to the light propagation end of the second substrate 12.

[0083] Among them, the second hollow area is opposite to the first hollow area. This design is conducive to allowing more light propagating by total internal reflection in the second substrate 12 to enter the first substrate 11 and increasing the number of coupled-out light rays.

[0084] Among them, the transmissive-reflective separation layer 40 includes at least one layer of semi-transmissive and semi-reflective film.

[0085] Of course, the transmissive-reflective separation layer 40 can also be a customized semi-transmissive and semi-reflective film formed by multiple film materials.

[0086] In some examples of this application, referring to Figure 6 , an anti-reflection film 50 is provided at some positions between the first substrate 11 and the second substrate 12, and the anti-reflection film 50 is located on the path of light propagating from the first substrate 11 to the second substrate 12.

[0087] Referring to Figure 6 , by adding a local anti-reflection film 50 at some positions between the first substrate 11 and the second substrate 12, part of the light can first transmit into the second substrate 12 with a higher efficiency, such as >99%, at the position where the anti-reflection film 50 is provided, and then be reflected and partially transmitted multiple times in the second substrate 12.

[0088] Between the first substrate 11 and the second substrate 12, not limited to adding one anti-reflection film 50, the anti-reflection film 50 can also be added as needed.

[0089] In some examples of this application, referring to Figure 7 and Figure 8 , the anti-reflection film 50 can also be located between the light transmission end of the second substrate 12 and the first substrate 11.

[0090] In some examples of this application, referring to Figure 7 and Figure 8 , the optical transmission device further includes a third substrate 13 and a fourth substrate 14, and the third substrate 13 and the fourth substrate 14 are sequentially arranged on the side of the second substrate 12 away from the first substrate 11. An anti-reflection film 50 is provided at some positions between the first substrate 11 and the second substrate 12, and a transmissive-reflective separation layer 40 and an anti-reflection film 50 are respectively provided at some positions between the second substrate 12 and the third substrate 13.

[0091] Among them, the anti-reflection film 50 and the transmissive-reflective separation layer are arranged staggeredly in the stacking direction.

[0092] In some examples of this application, please continue to refer to Figure 7 and Figure 8, between the first substrate 11 and the second substrate 12: an anti-reflection film 50 is provided at the position where light exits from the first substrate 11 to other substrates and at the position corresponding to the light transmission end of the second substrate 12; and a transmissive-reflective separation layer 40 and an anti-reflection film 50 are provided at intervals between the second substrate 12 and the third substrate 13, wherein the transmissive-reflective separation layer 40 is close to the position where light exits from the second substrate 12 to the third substrate 13.

[0093] When designing the optical structure of the optical transmission device provided by the embodiment of the present application, it should not be limited to additionally adding a second substrate 12, or a transmissive-reflective separation layer 40, or an anti-reflection film 50. It can be any number of thin substrates (with a thickness of about 10 um to 500 um), and then combined with the transmissive-reflective separation layer 40 and / or the anti-reflection film 50, and / or various combinations of independent thin substrates respectively.

[0094] It should be noted that the anti-reflection film 50 can be provided on each newly added substrate.

[0095] In some examples of the present application, see Figure 7 , the light input element 20 and the light output element 30 are located on the surface of the first substrate 11 facing away from the second substrate 12. Or, see Figure 8 , the light input element 20 is located on the surface of the first substrate 11 close to the second substrate 12, and the light output element 30 is located on the surface of the first substrate 11 facing away from the second substrate 12.

[0096] In some examples of the present application, the light input element 20 and the light output element 30 are diffractive optical elements.

[0097] Among them, the light input element 20 can be, for example, a one-dimensional grating.

[0098] Among them, the light output element 30 can be, for example, a combination of multiple one-dimensional gratings, or a two-dimensional grating.

[0099] In the present application, no specific limitation is imposed on the grating type of the light input element 20 and the light output element 30.

[0100] The optical transmission device provided by the embodiment of the present application can be applied to the optical waveguide element (lens) in a head-mounted display device. The head-mounted display device is, for example, an AR display device, and of course, it can also be an MR display device or an XR display device.

[0101] According to another aspect of the present application, a head-mounted display device is further provided. The head-mounted display device includes a housing and the optical transmission device as described above. The optical transmission device is disposed in the housing, and at least one optical transmission device is provided.

[0102] For the specific implementation of the head-mounted display device according to the embodiments of the present application, reference may be made to the above-described embodiments of the optical transmission device. Therefore, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated one by one here.

[0103] In the above embodiments, the differences between the embodiments are mainly described. As long as the different optimization features between the embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0104] Although some specific embodiments of the present application have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for illustration purposes and not for limiting the scope of the present application. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. An optical transmission device, characterized in that, include: A first substrate (11); A second substrate (12), the second substrate (12) being arranged on one side of the first substrate (11), and the second substrate (12) at least partially covering the first substrate (11); A light input element (20) and a light output element (30) are arranged on the first substrate (11); A portion of the light coupled into the first substrate (11) through the light input element (20) is totally reflected in the first substrate (11) and propagates to the light output element (30) before being emitted, while another portion of the light is emitted into the second substrate (12) and propagates by total reflection and is transmitted back to the first substrate (11) multiple times before finally propagating to the light output element (30) before being emitted.

2. The optical transmission device according to claim 1, characterized in that, The first substrate (11) and the second substrate (12) have different refractive indices.

3. The optical transmission device according to claim 1, characterized in that, The thickness of the second substrate (12) is 10 um to 500 um.

4. The optical transmission device according to claim 1, characterized in that, A transmissive-reflective separation layer (40) is provided between the first substrate (11) and the second substrate (12).

5. The optical transmission device according to claim 4, characterized in that, The transmissive-reflective separation layer (40) is arranged in a local area on the surface of the first substrate (11) close to the second substrate (12), and is located on a path for light to propagate from the first substrate (11) to the second substrate (12).

6. The optical transmission device according to claim 5, characterized in that, The second substrate (12) covers the transmissive-reflective separation layer (40), and the size of the second substrate (12) matches the size of the transmissive-reflective separation layer (40).

7. The optical transmission device according to claim 5, characterized in that, The second substrate (12) covers the transmissive-reflective separation layer (40), and the transmissive-reflective separation layer (40) forms a first hollow region at an end close to the end where light is emitted from the first substrate (11) toward the second substrate (12).

8. The optical transmission device according to claim 7, characterized in that, A second hollow area is formed at a position of the transmissive-reflective separation layer (40) close to the light propagation end of the second substrate (12).

9. The optical transmission device according to any one of claims 4-8, characterized in that, The transflective separation layer (40) comprises at least one layer of semi-reflective and semi-transmissive film.

10. The optical transmission device according to claim 1, characterized in that, An anti-reflection film (50) is provided at a portion of the position between the first substrate (11) and the second substrate (12); The anti-reflection film (50) is located on a path along which light propagates from the first substrate (11) to the second substrate (12).

11. The optical transmission device according to claim 10, characterized in that, The anti-reflection film (50) is located between the light transmission end of the second substrate (12) and the first substrate (11).

12. The optical transmission device according to claim 1, characterized in that, The optical transmission device further comprises a third substrate (13) and a fourth substrate (14), wherein the third substrate (13) and the fourth substrate (14) are sequentially arranged on a side of the second substrate (12) away from the first substrate (11); An anti-reflection film (50) is provided at a portion between the first substrate (11) and the second substrate (12), and a transmissive-reflection separation layer (40) and an anti-reflection film (50) are provided at a portion between the second substrate (12) and the third substrate (13).

13. The optical transmission device according to claim 12, characterized in that, Between the first substrate (11) and the second substrate (12): An anti-reflection film (50) is provided at a position where light is emitted from the first substrate (11) to other substrates and at a position corresponding to a light transmission end of the second substrate (12); and A transmissive and reflective separation layer (40) and an antireflection film (50) are disposed at intervals between the second substrate (12) and the third substrate (13), wherein the transmissive and reflective separation layer (40) is located at a position where light exits from the second substrate (12) and is incident on the third substrate (13).

14. The optical transmission device according to claim 1, characterized in that, The light input element (20) and the light output element (30) are located on a surface of the first substrate (11) facing away from the second substrate (12); or, The light input element (20) is located on a surface of the first substrate (11) close to the second substrate (12), and the light output element (30) is located on a surface of the first substrate (11) facing away from the second substrate (12).

15. The optical transmission device according to claim 1, characterized in that,The light input element (20) and the light output element (30) are diffractive optical elements.

16. A head-mounted display device, characterized in that, Comprising: A housing; and The optical transmission device according to any one of claims 1-15.

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