Light guide device and head-mounted display equipment
By designing a double-layer waveguide solution in the embossed grating waveguide solution, using the new layout of the double-layer substrate and two optical input components, the inefficiency problem of the embossed grating waveguide solution in terms of coupling efficiency is solved, and a higher optical coupling efficiency is achieved.
Patent Information
- Application Number
- CN202311687671.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-08
- Publication Date
- 2025-06-10
AI Technical Summary
The embossed grating waveguide solution has low coupling efficiency, especially in augmented reality technology, which is difficult to effectively improve optical efficiency.
A double-layer waveguide solution is designed to match two optical input elements through a double-layer substrate and make a new layout of their positions so that the two optical input elements will not affect the coupling of light from each other, while improving the coupling efficiency.
It realizes the optical coupling efficiency without limiting the coupling grating type, and is suitable for optical display solutions in augmented reality technology.
Smart Images
Figure CN120122337A_ABST
Abstract
Description
Technical Field
[0001] Embodiments of the present application relate to the field of optical imaging technologies, and more specifically, to a light guiding device and a head-mounted display device. Background Art
[0002] Augmented reality technology (AR) is a technology that combines virtual information with the real world and is gradually emerging in various industries. The optical waveguide solution is considered to be the best optical display solution for current augmented reality glasses. The optical waveguide solution is divided into a geometric waveguide solution, a relief grating waveguide solution, and a volume holographic waveguide solution. Considering the comprehensive process difficulty and optical effect, the relief grating waveguide solution is the most studied technical solution among the three. However, the relief grating waveguide has the problem of low optical efficiency, especially in terms of the coupling efficiency. Summary of the Invention
[0003] The purpose of the present application is to provide a new technical solution for a light guiding device and a head-mounted display device.
[0004] In a first aspect, the present application provides a light guiding device. The light guiding device includes a substrate, a first optical input element, and a second optical input element;
[0005] wherein the substrate includes a first substrate and a second substrate stacked one on top of the other;
[0006] The first optical input element is disposed on the surface of the first substrate facing away from the second substrate, the second optical input element is disposed on the surface of the second substrate facing away from the first substrate, and the first optical input element and the second optical input element are at least partially staggeredly distributed in the thickness direction of the substrate.
[0007] Optionally, metal film layers are respectively covered on the first optical input element and the second optical input element.
[0008] Optionally, there is a gap between the first substrate and the second substrate.
[0009] Optionally, the second optical input element is configured to couple incident light into the second substrate and diffract the incident light into a first light ray and a second light ray;
[0010] The second substrate is configured to make the first light ray propagate in a total reflection manner and make the second light ray transmit into the first substrate.
[0011] Optionally, the first optical input element is configured to diffract the second light ray entering the first substrate, and the first substrate is configured to make the second light ray modulated by the second optical input element and the first optical input element together propagate in a total reflection manner.
[0012] Optionally, the diffraction angle θ corresponding to the coupling efficiency of the second light ray after passing through the first optical input element is:
[0013] θ = sin -1 (sinθ 0 + λ / d1n(λ));
[0014] where θ 0 is the incident angle of the second light ray, λ is the wavelength of the second light ray, d1 is the period of the first optical input element, and n(λ) is the refractive index of the first substrate.
[0015] Optionally, the first optical input element and the second optical input element are diffraction gratings.
[0016] Optionally, the material of the metal film layer includes at least one of silver, aluminum, nickel, and titanium.
[0017] Optionally, the light guiding device further includes an optical output element, the optical output element is disposed on the substrate, and the optical output element is configured to output the light ray propagating to the optical output element;
[0018] During the process that the first light ray modulated by the second optical input element is coupled out by the optical output element after being coupled into the second substrate, the grating vector K 2 of the second optical input element O2 and the grating vector K
[0019] During the process that the second light ray jointly modulated by the second optical input element and the first optical input element is coupled out by the optical output element after being coupled into the first substrate, the grating vector K 2 of the second optical input element, 1 the grating vector K O2 and the grating vector K
[0020] In a second aspect, the present application provides a head-mounted display device. The head-mounted display device includes:
[0021] A housing; and
[0022] The light guiding device as described in the first aspect.
[0023] One beneficial effect of the embodiments of the present application is:
[0024] The light guiding device provided by the embodiment of the present application is a double-layer waveguide solution. By designing a double-layer substrate and two optical input elements, and making a new layout of the positions of the two optical input elements, the two optical input elements will not affect each other's light coupling, and the coupling efficiency can also be improved.
[0025] Other features and advantages of the present specification will become clear through the following detailed description of the exemplary embodiments of the present specification with reference to the accompanying drawings. Description of the Drawings
[0026] The drawings incorporated in the specification and constituting a part of the specification illustrate the embodiments of the present specification, and together with the description thereof are used to explain the principles of the present specification.
[0027] Figure 1 One of the optical path diagrams of the light guiding device provided by the embodiment of the present application;
[0028] Figure 2 Another optical path diagram of the light guiding device provided by the embodiment of the present application;
[0029] Figure 3 A blazed grating and its corresponding diffraction efficiency diagram;
[0030] Figure 4 Adding a metal film layer on the blazed grating and its corresponding diffraction efficiency diagram;
[0031] Figure 5a and Figure 5b respectively are Figure 1 The K-Space diagrams of two optical paths in the optical path diagram shown in
[0032] Figure 6a and Figure 6b respectively are Figure 2 The K-Space diagrams of two optical paths in the optical path diagram shown in
[0033] Description of the Reference Numerals:
[0034] 1. First substrate; 2. Second substrate; 3. First optical input element; 4. Second optical input element; 01. First light ray; 02. Second light ray; 001. Blazed grating; 002. Air; 003. Aluminum metal layer. Detailed Embodiments
[0035] 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 of components and steps, numerical expressions and values set forth in these embodiments do not limit the scope of the present application.
[0036] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way a limitation on the present application or its application or use.
[0037] 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 considered as part of the specification.
[0038] In all the examples shown and discussed herein, any specific values should be construed as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments may have different values.
[0039] It should be noted that like reference numerals and letters denote like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
[0040] The light guiding device and the head-mounted display device provided by the embodiments of the present application will be described in detail below with reference to the accompanying drawings.
[0041] According to one aspect of the embodiments of the present application, a light guiding device is provided. The light guiding device is, for example, a diffractive optical waveguide element and can be applied to an AR diffractive optical solution.
[0042] The light guiding device provided by the embodiments of the present application, see Figure 1 and Figure 2 , the light guiding device includes a substrate, a first optical input element 3 and a second optical input element 4; wherein, the substrate includes a first substrate 1 and a second substrate 2 stacked up and down. Wherein, the first optical input element 3 is disposed on the surface of the first substrate 1 facing away from the second substrate 2, the second optical input element 4 is disposed on the surface of the second substrate 2 facing away from the first substrate 1, and the first optical input element 3 and the second optical input element 4 are at least partially staggeredly distributed in the thickness direction of the substrate.
[0043] Currently, in order to improve the coupling efficiency of the coupling grating, the coupling grating is generally set as an inclined grating or a blazed grating, etc. Although this kind of coupling grating design can improve the coupling efficiency, it also limits the type of the coupling grating to a certain extent, and the ability to improve the coupling efficiency is limited.
[0044] The light guiding device provided by the embodiments of the present application is a double-layer waveguide solution. By designing a double-layer substrate with two optical input elements, namely the above-mentioned first optical input element 3 and second optical input element 4, and making a new layout of the positions of the two optical input elements, the two optical input elements will not affect each other's coupling of incident light, and the coupling efficiency can also be improved.
[0045] For example, the optical solution provided by the embodiments of the present application can couple two light rays of different wavelengths into two different substrates respectively. Of course, it can also divide the image light rays with a large field of view into two image light rays with small fields of view and propagate them in two different substrates respectively. This method is very conducive to improving the coupling efficiency. Moreover, the type of the coupling grating can be not limited while improving the coupling efficiency.
[0046] For example, the first optical input element 3 and the second optical input element 4 are respectively arranged on two opposite outer sides of the double-layer substrate and are staggered by a certain distance in the thickness direction of the substrate. This design can prevent the first optical input element 3 from affecting the coupling of the incident light rays into the second optical input element 4.
[0047] In some examples of the present application, metal film layers are respectively covered on the first optical input element 3 and the second optical input element 4.
[0048] According to the light guiding device provided by the embodiments of the present application, it is a double-layer waveguide, and metal film layers can be respectively plated on the surfaces of the first optical input element 3 and the second optical input element 4. That is to say, the optical solution of the embodiments of the present application includes a double-layer substrate, and the first optical input element 3 and the second optical input element 4 respectively plated with metal film layers. In this way, the coupling efficiency can be further improved.
[0049] See Figure 3 , in Figure 3 the left figure, 1R is the coupling order, that is, the diffraction efficiency of 1R determines the coupling efficiency of the light guiding device such as an optical waveguide. The refractive index of the blazed grating 001 is about 1.9, which is the same as the refractive index of the substrate of the waveguide. The grating depth is about 80 nm, the wavelength of the incident light rays is 520 nm, and the surface of the blazed grating 001 is air 002. See Figure 4 , in Figure 4 the left figure, a schematic diagram of plating a metal aluminum layer 003 on the surface of the blazed grating 001 is shown, that is Figure 4 it is a metal aluminum blazed grating in Figure 3 The difference between the blazed grating 001 in Figure 4 and the blazed grating 001 in Figure 4 is that a metal aluminum layer 003 is plated on the surface of the blazed grating 001 in
[0050] See respectively Figure 3 the right figure in Figure 4 and the right figure in
[0051] It should be noted here that for Figure 3 and Figure 4 the simulation is to illustrate that depositing a metal layer on the coupling grating can improve the reflection coupling efficiency.
[0052] The light guiding device provided by the embodiment of the present application, based on the special layout of the first optical input element 3 and the second optical input element 4 on the double-layer waveguide, refer to Figure 1 and Figure 2 , the incident light will first propagate to the second optical input element 4 on the second substrate 2 located in the lower layer, and then can directly pass through the second substrate 2 and enter the first substrate 1 located above and be projected onto the first optical input element 3. In this way, in the double-layer substrate, the light propagation will not be interfered by the metal film layer on any optical input element, and the light can smoothly enter the first substrate 1 from the second substrate 2 without being blocked by any metal film layer, and all the advantages of the metal film layer grating can be exerted.
[0053] It should be noted that the first substrate 1 and the second substrate 2 are light-transmitting thin sheets.
[0054] In some examples of the present application, there is a gap between the first substrate 1 and the second substrate 2.
[0055] It should be noted that there needs to be a certain gap between the first substrate 1 and the second substrate 2. However, the size of this gap is not limited in the present application and can be designed according to requirements such as the thickness dimension of the entire light guiding device. For example, the gap can be designed to be very small.
[0056] In some examples of the present application, refer to Figure 1 and Figure 2 , the second optical input element 4 is used to couple the incident light into the second substrate 2 and diffract the incident light into a first light ray 01 and a second light ray 02. The second substrate 2 is used to make the first light ray 01 propagate in a total reflection manner and make the second light ray 02 transmit into the first substrate 1.
[0057] In some examples of the present application, refer to Figure 1 and Figure 2 , the first optical input element 3 is used to diffract the second light ray 02 entering the first substrate 1, and the first substrate 1 is used to make the second light ray 02 modulated by the second optical input element 4 and the first optical input element 3 propagate in a total reflection manner.
[0058] According to the above two examples, refer to Figure 1 and Figure 2, after the incident light outside the light guide device enters the light guide device, its optical propagation path is as follows: the incident light is first diffraction-modulated by the second optical input element 4, and then, according to the difference in the diffraction directions, the light is divided into two beams:
[0059] Among them, one beam of light is the first light ray 01, and the propagation angle of the first light ray 01 satisfies the total internal reflection condition of the second substrate 2, so that the first light ray 01 undergoes total internal reflection propagation in the second substrate 2.
[0060] Among them, the other beam of light is the second light ray 02, and the second light ray 02 does not satisfy the total internal reflection condition of the second substrate 2. The second light ray 02 will pass through the second substrate 2 and enter the first substrate 1. After the second light ray 02 is diffraction-adjusted by the first optical input element 3, the propagation angle satisfies the total internal reflection condition of the first substrate 1. At this time, the second light ray 02 will undergo total internal reflection propagation in the first substrate 1.
[0061] In some examples of the present application, the diffraction angle θ corresponding to the coupling efficiency of the second light ray 02 after passing through the first optical input element 3 is: θ = sin -1 (sinθ 0 + λ / d1n(λ)); where θ 0 is the incident angle of the second light ray 02, λ is the wavelength of the second light ray 02, d1 is the period of the first optical input element 3, and n(λ) is the refractive index of the first substrate 1.
[0062] Since the refractive index of the first substrate 1 and the period of the first optical input element 3 are known, the modulation of the second light ray 02 by the first optical input element 3 and the total internal reflection propagation in the first substrate 1 are related to the incident angle and wavelength of the second light ray 02, and thus are related to the incident angle and wavelength of the incident light.
[0063] See Figure 5a and Figure 5b , which respectively correspond to Figure 1 the transmission paths of two light rays with different wavelengths. Among them, the two light rays with different wavelengths are the first light ray 01 and the second light ray 02, and the two light rays with different wavelengths are projected onto the second optical input element 4 at the same incident angle (same field of view).
[0064] Specifically, Figure 5a is the coupling K-Space diagram of the first light ray 01. After being modulated by the second optical input element 4, the first light ray 01 directly undergoes total internal reflection propagation in the second substrate 2. Figure 5bIt is the K-Space diagram for the coupling-in of the second light ray 02. After being jointly modulated by the second optical input element 4 and the first optical input element 3, the second light ray 02 undergoes total internal reflection propagation in the first substrate 1.
[0065] From Figure 5a and Figure 5b the relationship therein, it can be known that: k2(λ1)≈k1(λ2)+k2(λ2), λ1>λ2 (this relationship reflects that the second light ray 02 needs to be jointly modulated by the second optical input element 4 and the first optical input element 3). Among them, ki(λj) = λj / din(λj), i = 1, 2; j = 1, 2; din is the period of the first optical input element 3. This embodiment realizes the effect of coupling two light rays with different wavelengths into two layers of substrates respectively.
[0066] Referring to Figure 6a and Figure 6b , they respectively correspond to Figure 2 the image light rays of the same wavelength but different fields of view in 0 . They are the first light ray 01 and the second light ray 02 respectively. Here, the first light ray 01 and the second light ray 02 have the same wavelength, but different incident angles when projected onto the second optical input element 4.
[0067] Specifically, Figure 6a is the K-Space diagram for the coupling-in of the first light ray 01. After being modulated by the second optical input element 4, the first light ray 01 directly undergoes total internal reflection propagation in the second substrate 2. Figure 6b is the K-Space diagram for the coupling-in of the second light ray 02. The image light rays of a part of the field of view, that is, the first light ray 01, are directly coupled into the second substrate 2 through the second optical input element 4, and the image light rays of another part of the field of view, that is, the second light ray 02, undergo total internal reflection propagation in the first substrate 1 after being jointly modulated by the second optical input element 4 and the first optical input element 3. This example realizes the effect that a large field of view is divided into two small fields of view and propagates in two layers of substrates respectively.
[0068] In some examples of the present application, the first optical input element 3 and the second optical input element 4 are diffraction gratings.
[0069] It should be noted that in the present application, the grating types of the first optical input element 3 and the second optical input element 4 may not be limited.
[0070] Optionally, the grating types of the first optical input element 3 and the second optical input element 4 can be one or more of surface relief gratings such as blazed gratings, tilted gratings, binary gratings, and stepped gratings. Applying any type of grating to the solution of the present application can improve the coupling efficiency.
[0071] In some examples of the present application, the material of the metal film layer includes at least one of silver, aluminum, nickel, and titanium.
[0072] In some examples of the present application, the light guiding device further includes an optical output element ( Figure 1 and Figure 2 not shown in [the figure]), the optical output element is disposed on the substrate, and the optical output element is configured to output the light that propagates to the optical output element.
[0073] During the process that the first light ray 01 modulated by the second optical input element 4 is coupled out by the optical output element after being coupled into the second substrate 2, the grating vector K of the second optical input element 4 2 and the grating vector K of the optical output element O2 sum to zero;
[0074] During the process that the second light ray 02 modulated by the second optical input element 4 and the first optical input element 3 together is coupled out by the optical output element after being coupled into the first substrate 1, the grating vector K of the second optical input element 4 2 , the grating vector K of the first optical input element 3 1 and the grating vector K of the optical output element O2 sum to zero.
[0075] According to another aspect of the present application, embodiments of the present application further provide a head-mounted display device. The head-mounted display device includes a housing and the light guiding device as described above.
[0076] The light guiding device is, for example, a diffractive optical waveguide element, and is disposed in the housing.
[0077] The head-mounted display device includes an AR smart glasses or an AR smart helmet, etc., and the embodiments of the present application do not limit this.
[0078] For the specific implementation manners of the head-mounted display device of the embodiments of the present application, reference may be made to the above-described embodiments of the diffractive optical structure and the light guiding device. Therefore, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated herein one by one.
[0079] In the above embodiments, the differences between the various embodiments are mainly described. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a more optimal embodiment. Considering the simplicity of the writing, they will not be elaborated herein.
[0080] 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 for illustrative purposes only 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. A light guiding device, characterized in that, it includes a substrate, a first optical input element (3) and a second optical input element (4); wherein, the substrate includes a first substrate (1) and a second substrate (2) stacked one on top of the other; the first optical input element (3) is disposed on the surface of the first substrate (1) facing away from the second substrate (2), the second optical input element (4) is disposed on the surface of the second substrate (2) facing away from the first substrate (1), and the first optical input element (3) and the second optical input element (4) are at least partially staggeredly distributed in the thickness direction of the substrate.
2. The light guiding device according to claim 1, characterized in that, metal film layers are respectively covered on the first optical input element (3) and the second optical input element (4).
3. The light guiding device according to claim 1 or 2, characterized in that, there is a gap between the first substrate (1) and the second substrate (2).
4. The light guiding device according to claim 3, characterized in that, the second optical input element (4) is used to couple incident light into the second substrate (2), and diffract the incident light into a first light ray (01) and a second light ray (02); the second substrate (2) is used to make the first light ray (01) propagate in a total reflection manner, and make the second light ray (02) transmit into the first substrate (1).
5. The light guiding device according to claim 4, characterized in that, the first optical input element (3) is used to diffract the second light ray (02) entering the first substrate (1), and the first substrate (1) is used to make the second light ray (02) modulated by the second optical input element (4) and the first optical input element (3) together propagate in a total reflection manner.
6. The light guiding device according to claim 5, characterized in that, the diffraction angle θ corresponding to the coupling efficiency of the second light ray (02) after passing through the first optical input element (3) is: θ = sin -1 (sinθ 0 + λ / d1n(λ)); where θ 0 is the incident angle of the second light beam (02), λ is the wavelength of the second light beam (02), d1 is the period of the first optical input element (3), and n(λ) is the refractive index of the first substrate (1).
7. The light guiding device according to claim 3, characterized in that, the first optical input element (3) and the second optical input element (4) are diffraction gratings.
8. The light guiding device according to claim 2, characterized in that, the material of the metal film layer includes at least one of silver, aluminum, nickel and titanium.
9. The light guiding device according to claim 5, characterized in that, the light guiding device further includes an optical output element, the optical output element is disposed on the substrate, and the optical output element is used to output the light ray propagating to the optical output element; During the process that the first light ray (01) modulated by the second optical input element (4) is coupled out by the optical output element after being coupled into the second substrate (2), the grating vector K of the second optical input element (4) 2 and the grating vector K of the optical output element O2 sum to zero; During the process that the second light beam (02) jointly modulated by the second optical input element (4) and the first optical input element (3) is coupled out by the optical output element after being coupled into the first substrate (1), the grating vector K of the second optical input element (4) 2 , the grating vector K of the first optical input element (3) 1 and the grating vector K of the optical output element O2 sum to zero.
10. A head-mounted display device, characterized in that, it includes: a housing; and, the light guiding device according to any one of claims 1-9.