Diffraction optical waveguide device, optical waveguide design method and augmented reality equipment

Abstract

The invention provides a diffractive optical waveguide device, an optical waveguide design method and augmented reality equipment, which can improve the color uniformity to a certain extent and ensure the efficiency of an optical waveguide. The diffractive optical waveguide device includes: a waveguide substrate; the coupling-in unit is provided with a first coupling-in light path and a second coupling-in light path which are separated from each other, and is used for dividing the image light into two paths and coupling the image light into the waveguide substrate so as to propagate along the first coupling-in light path and the second coupling-in light path respectively; the turning unit is arranged on the waveguide substrate and comprises a first turning grating and a second turning grating which are located in the first coupling-in light path and the second coupling-in light path respectively, and the first turning grating and the second turning grating are both one-dimensional turning gratings; the coupling-out unit is arranged on the waveguide substrate and comprises a first coupling-out grating corresponding to the first turning grating and a second coupling-out grating corresponding to the second turning grating, and the first coupling-out grating and the second coupling-out grating are two-dimensional coupling-out gratings which are not overlapped with each other; the grating period of the first out-coupling grating is different from the grating period of the second out-coupling grating.

Description

Technical Field

[0001] The present invention relates to the technical field of diffractive waveguides, and particularly to a diffractive optical waveguide device, an optical waveguide design method, and an augmented reality device. Background Art

[0002] As the most important technical path recognized in the industry for AR (Augmented Reality) optical displays, the diffractive optical waveguide solution provides advantages such as thinness and lightness, and an appearance similar to that of conventional glasses for augmented reality devices. Since the diffractive optical waveguide solution uses the diffraction of gratings to achieve the turning of the entire optical path, its diffraction effect also causes relatively large dispersion of light in different wavelength bands, resulting in poor color uniformity. Currently, a common solution to this problem is to use two or three layers of optical waveguides to separately transmit light in different wavelength bands to correct chromatic aberration, but this also brings disadvantages such as increased thickness and weight. Therefore, the solution of using a single-chip full-color optical waveguide to solve color uniformity and weight has become an important current requirement for diffractive optical waveguides.

[0003] Currently, the existing solutions for improving color uniformity in single-chip optical waveguides are either to use the high-order diffraction of gratings to make light in different wavelength bands propagate in different orders to achieve the purpose of achromatism, or to use a single-layer double-sided or single-layer double-K domain channel superposition scheme to achieve the purpose of improving color uniformity. However, for the single-chip full-color optical waveguide solution that separately transmits different wavelength bands in high-order modes, not only will the efficiency continuously degrade during transmission in different orders, making it difficult to meet the general efficiency requirements of the waveguide, but also the mutual interference between multi-order diffractions will generate serious ghost images, resulting in a difficult filtering film process for the angle response and not being practical. For the single-chip full-color optical waveguide solution with multiple K-domain channels, it will also sacrifice a great deal of efficiency, and a large number of ghost images will be formed due to the high overlap of the grating regions where different K vectors couple out to generate a large amount of coupled-out light that does not belong to the target coupling-out scheme. Summary of the Invention

[0004] One advantage of the present invention is to provide a diffractive optical waveguide device, an optical waveguide design method, and an augmented reality device, which can improve color uniformity to a certain extent while ensuring the efficiency of the optical waveguide.

[0005] Another advantage of the present invention is to provide a diffractive optical waveguide device, an optical waveguide design method, and an augmented reality device. In one embodiment of the present invention, the diffractive optical waveguide device can separate the light wavelength bands with two K-domain distributions for separate transmission and coupling out, so as to ensure the independent transmission of the light with two K-domain distributions that are respectively beneficial to the transmission of blue light and red light, facilitating the reduction of ghost images.

[0006] Another advantage of the present invention lies in providing a diffractive optical waveguide device, an optical waveguide design method, and an augmented reality device. In one embodiment of the present invention, the diffractive optical waveguide device can introduce a one-dimensional turning grating to share the two-dimensional pupil expansion effect in the first half of the light transmission, so as to ensure the separation of the optical paths in the two half regions while avoiding unnecessary coupling out caused by premature introduction of a two-dimensional grating, thereby improving the efficiency of the optical waveguide.

[0007] Another advantage of the present invention lies in providing a diffractive optical waveguide device, an optical waveguide design method, and an augmented reality device. In one embodiment of the present invention, the diffractive optical waveguide device can not only achieve the priority transmission of blue light and red light in the two half regions respectively to improve the color uniformity of a single chip, but also can specifically weaken the ghost image problem caused by the high overlap of the two K domains in a conventional full-color optical waveguide.

[0008] Another advantage of the present invention lies in providing a diffractive optical waveguide device, an optical waveguide design method, and an augmented reality device. To achieve the above object, expensive materials or complex structures are not required in the present invention. Therefore, the present invention successfully and effectively provides a solution, not only providing a simple diffractive optical waveguide device, an optical waveguide design method, and an augmented reality device, but also increasing the practicability and reliability of the diffractive optical waveguide device, the optical waveguide design method, and the augmented reality device.

[0009] To achieve at least one of the above advantages or other advantages and objects of the present invention, the present invention provides a diffractive optical waveguide device, comprising:

[0010] A waveguide substrate;

[0011] An input coupling unit having a first input coupling optical path and a second input coupling optical path separated from each other, for coupling image light into the waveguide substrate in two paths to propagate along the first input coupling optical path and the second input coupling optical path respectively;

[0012] A turning unit, including a first turning grating disposed on the waveguide substrate and in the first input coupling optical path and a second turning grating disposed on the waveguide substrate and in the second input coupling optical path, wherein both the first turning grating and the second turning grating are one-dimensional turning gratings; and

[0013] An output coupling unit, including a first output coupling grating disposed on the waveguide substrate and corresponding to the first turning grating and a second output coupling grating disposed on the waveguide substrate and corresponding to the second turning grating, wherein the first output coupling grating and the second output coupling grating are non-overlapping two-dimensional output coupling gratings, and the grating period of the first output coupling grating is different from the grating period of the second output coupling grating.

[0014] According to an embodiment of the present application, the grating period range of the first output grating is from 310 nm to 330 nm; the grating period range of the second output grating is from 410 nm to 430 nm.

[0015] According to an embodiment of the present application, the grating vector modulus of the first output grating is greater than that of the second output grating.

[0016] According to an embodiment of the present application, the coupling-in unit is a two-dimensional coupling-in grating disposed on the waveguide substrate; the two-dimensional coupling-in grating has two grating vectors respectively along the first coupling-in optical path and the second coupling-in optical path, and the grating vector modulus along the first coupling-in optical path is greater than that along the second coupling-in optical path.

[0017] According to an embodiment of the present application, the two-dimensional coupling-in grating, the first turning grating, the second turning grating, the first output grating, and the second output grating are all located on the front surface of the waveguide substrate, wherein the first output grating and the second output grating are spliced with each other.

[0018] According to an embodiment of the present application, the two-dimensional coupling-in grating, the first output grating, and the second output grating are all two-dimensional gratings distributed in a truncated rhombus shape; the first turning grating and the second turning grating are one-dimensional blazed gratings.

[0019] According to an embodiment of the present application, the coupling-in unit includes a first coupling-in grating and a second coupling-in grating disposed on the waveguide substrate; wherein the first coupling-in grating and the second coupling-in grating are both one-dimensional coupling-in gratings, and the first coupling-in grating has a grating vector along the first coupling-in optical path, and the second coupling-in grating has a grating vector along the second coupling-in optical path.

[0020] According to an embodiment of the present application, the first coupling-in grating and the second coupling-in grating are both located on the front surface of the waveguide substrate; or, the first coupling-in grating and the second coupling-in grating are respectively located on the front surface or the back surface of the waveguide substrate.

[0021] According to an embodiment of the present application, the first turning grating and the second turning grating are symmetrically arranged; the angle between the grating vector of the first turning grating and the X-axis is 120° + a + n * 180°, where a is the angle between the grating vector of the first output grating and the X-axis, and n is a positive integer.

[0022] According to an embodiment of the present application, the grating vectors of the coupling-in unit, the turning unit, and the output unit form a closed equilateral triangle in the K space.

[0023] According to another aspect of the present application, the present application further provides an augmented reality device, including:

[0024] An optical engine; and

[0025] Any of the above-described diffractive optical waveguide devices, which is disposed on the light output side of the optical engine for transmitting image light from the optical engine.

[0026] According to an embodiment of the present application, the augmented reality device further includes a semi-transmissive semi-reflective element and a total reflection element. The semi-transmissive semi-reflective element is obliquely disposed in the optical path between the optical engine and the first coupling grating of the diffractive optical waveguide device. The total reflection element is disposed on the reflection side of the semi-transmissive semi-reflective element, and the second coupling grating of the diffractive optical waveguide device is located on the reflection side of the total reflection element.

[0027] According to another aspect of the present application, the present application further provides an optical waveguide design method, including the steps of:

[0028] Constructing a first closed K domain that is conducive to the transmission of light in a first band in the upper half partition of the waveguide substrate in the K space; and

[0029] Constructing a second closed K domain that is conducive to the transmission of light in a second band with a different bandwidth from that of the first band in the lower half partition of the waveguide substrate in the K space.

[0030] According to an embodiment of the present application, both the first closed K domain and the second closed K domain include the grating vectors of the coupling unit, the grating vectors of the turning unit, and the grating vectors of the coupling-out unit. Among them, the grating vectors of the coupling unit, the grating vectors of the turning unit, and the grating vectors of the coupling-out unit in each closed K domain form a closed equilateral triangle in the K space.

[0031] According to an embodiment of the present application, the first closed K domain is conducive to the transmission of blue light, the second closed K domain is conducive to the transmission of red light, and the moduli of the grating vectors of the coupling unit and the coupling-out unit in the first closed K domain are both greater than the moduli of the grating vectors in the second closed K domain.

[0032] According to an embodiment of the present application, the included angle between the coupling-out grating vector located in the upper half partition of the waveguide substrate and the X axis is between amin and amin + 2°, where amin = arcsin(|kfy1| / |kout1|) + 180°, arcsin represents the arcsine function; kfy1 represents the coupling-out grating vector; kout1 represents the grating vector component of the semi-field angle on the Y axis in the K domain space.

[0033] According to an embodiment of the present application, the included angle between the grating vector of the coupling-in unit and the X-axis is a + 60°, where a is the included angle between the coupling-out grating vector of the upper half partition and the X-axis.

[0034] According to an embodiment of the present application, the K-vector distributions of each of the upper half partitions located on the waveguide substrate are symmetrically distributed about the X-axis with respect to the K-vector distributions of each of the lower half partitions located on the waveguide substrate. Description of the Drawings

[0035] Figure 1 is a schematic structural diagram of an augmented reality device according to an embodiment of the present application;

[0036] Figure 2 shows a first example of a diffractive optical waveguide device in the augmented reality device according to the above embodiment of the present application;

[0037] Figure 3 shows a schematic optical path diagram of the diffractive optical waveguide device according to the above first example of the present application;

[0038] Figure 4 shows a schematic diagram of the K-domain distribution of the diffractive optical waveguide device according to the above embodiment of the present application;

[0039] Figure 5 shows a top view schematic diagram of the two-dimensional grating in the diffractive optical waveguide device according to the above embodiment of the present application;

[0040] Figure 6 shows a side view schematic diagram of the one-dimensional grating in the diffractive optical waveguide device according to the above embodiment of the present application;

[0041] Figure 7 shows a schematic diagram of the vector action of the first coupling-out grating in the diffractive optical waveguide device according to the above embodiment of the present application;

[0042] Figure 8 shows a schematic diagram of the vector action of the second coupling-out grating in the diffractive optical waveguide device according to the above embodiment of the present application;

[0043] Figure 9 shows a partial schematic diagram of the action of the two-dimensional coupling-out grating on light in the diffractive optical waveguide device according to the above embodiment of the present application;

[0044] Figure 10 shows a second example of a diffractive optical waveguide device in the augmented reality device according to the above embodiment of the present application;

[0045] Figure 11 shows a third example of a diffractive optical waveguide device in the augmented reality device according to the above embodiment of the present application;

[0046] Figure 12 Schematic flow chart of an optical waveguide design method according to an embodiment of the present application.

[0047] Description of main component symbols: 1, diffractive optical waveguide device; 10, waveguide substrate; 101, upper half partition; 102, lower half partition; 103, front surface; 104, rear surface; 20, coupling-in unit; 201, first coupling-in optical path; 202, second coupling-in optical path; 21, two-dimensional coupling-in grating; 22, first coupling-in grating; 23, second coupling-in grating; 30, turning unit; 300, one-dimensional turning grating; 31, first turning grating; 32, second turning grating; 40, coupling-out unit; 400, two-dimensional coupling-out grating; 41, first coupling-out grating; 42, second coupling-out grating; 2, optical machine; 3, semi-transmissive semi-reflective element; 4, total reflection element. Detailed implementation manners

[0048] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments in the following description are only examples, and other obvious variations can be thought of by those skilled in the art. The basic principles defined in the following description can be applied to other implementation manners, variant solutions, improvement solutions, equivalent solutions, and other technical solutions that do not depart from the spirit and scope of the present invention.

[0049] Those skilled in the art should understand that in the disclosure of the present invention, the orientation or positional relationships indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting the present invention.

[0050] In the present invention, the term "a" in the claims and the specification should be understood as "one or more". That is, in one embodiment, the number of an element can be one, while in other embodiments, the number of the element can be multiple. Unless it is clearly indicated in the disclosure of the present invention that the number of the element is only one, the term "a" cannot be understood as being unique or single, and the term "a" cannot be understood as a limitation on the number.

[0051] In the description of the present invention, it should be understood that terms such as "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through a medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] In the description of this specification, the descriptions with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0053] Considering that the existing solutions for improving color uniformity of a single-chip optical waveguide either use the high-order diffraction of gratings to make light of different wavelength bands propagate in different orders to achieve the purpose of achromatism, or use the scheme of superimposing a single-layer double-K domain channel to achieve the purpose of improving color uniformity; however, while sacrificing efficiency significantly, these solutions will generate a large number of ghost images. To solve this problem, the present application creatively proposes a diffractive optical waveguide device, an optical waveguide design method, and an augmented reality device, which can improve color uniformity to a certain extent while ensuring the efficiency of the optical waveguide.

[0054] Specifically, referring to the accompanying drawings of the present application Figures 1 to 11 , according to an embodiment of the present application, an augmented reality device is provided, which may include an optical engine 2 and a diffractive optical waveguide device 1. The diffractive optical waveguide device 1 is disposed on the light output side of the optical engine 2 and is used for transmitting the image light from the optical engine 2 to the human eye for near-eye display, and at the same time, allowing the human eye to view the external environment through the diffractive optical waveguide device 1 to obtain an augmented reality experience.

[0055] More specifically, as Figures 1 to 3As shown, the diffractive optical waveguide device 1 may include a waveguide substrate 10, an input coupling unit 20, a turning unit 30, and an output coupling unit 40. The input coupling unit 20 may have a first input optical path 201 and a second input optical path 202 that are separated from each other, and are used to couple image light into the waveguide substrate 10 in two paths, so as to propagate along the first input optical path 201 and the second input optical path 202 respectively. The turning unit 30 may include a first turning grating 31 disposed on the waveguide substrate 10 and located in the first input optical path 201, and a second turning grating 32 disposed on the waveguide substrate 10 and located in the second input optical path 202. Both the first turning grating 31 and the second turning grating 32 are one-dimensional turning gratings 300. The output coupling unit 40 may include a first output coupling grating 41 disposed on the waveguide substrate 10 and corresponding to the first turning grating 31, and a second output coupling grating 42 disposed on the waveguide substrate 10 and corresponding to the second turning grating 32; the first output coupling grating 41 and the second output coupling grating 42 are non-overlapping two-dimensional output coupling gratings 400, and the grating period of the first output coupling grating 41 is different from the grating period of the second output coupling grating 42.

[0056] Thus, as Figure 3 shown, when the optical engine 2 projects image light, the input coupling unit 20 couples the image light into the waveguide substrate 10 in two paths, so as to propagate along the first input optical path 201 to the first turning grating 31 and along the second input optical path 202 to the second turning grating 32; furthermore, the image light propagating along the first input optical path 201 is pupil-expanded and turned by the first turning grating 31 to independently propagate to the first output coupling grating 41, and the image light propagating along the second input optical path 202 is pupil-expanded and turned by the second turning grating 32 to independently propagate to the second output coupling grating 42; finally, the first output coupling grating 41 separately pupil-expands and couples out the image light from the first turning grating 31, and the second output coupling grating 42 separately pupil-expands and couples out the image light from the second turning grating 32, so that the human eye can simultaneously receive the image light coupled out by the first output coupling grating 41 and the second output coupling grating 42 respectively for near-eye display.

[0057] It should be noted that, as Figure 2 and Figure 3 shown, since the first output coupling grating 41 and the second output coupling grating 42 are non-overlapping two-dimensional output coupling gratings 400, and the grating period of the first output coupling grating 41 is different from the grating period of the second output coupling grating 42, the first output coupling grating 41 is conducive to transmitting the first band light (such as blue light) that matches the grating period of the first output coupling grating 41, and the second output coupling grating 42 is conducive to transmitting the second band light (such as red light) that matches the grating period of the second output coupling grating 42; furthermore, as Figure 4As shown, the coupling-in unit 20, the first turning grating 31, and the first coupling-out grating 41 can construct a first closed K domain in the K space that is conducive to the transmission of light in the first wavelength band, and the coupling-in unit 20, the second turning grating 32, and the second coupling-out grating 42 can construct a second closed K domain in the K space that is conducive to the transmission of light in the second wavelength band, so that the light rays in the two closed K domains that are conducive to the transmission of light in different wavelength bands propagate independently and are coupled out, in order to weaken ghost images.

[0058] In other words, through the special arrangement of gratings, the diffractive optical waveguide device 1 of the present application first uses the one-dimensional turning grating 300 for transition, and then uses the two-dimensional coupling-out grating 400 for pupil expansion and coupling-out to separate the optical transmission of the two K domain distributions, ensuring the independent transmission of the light in the two K domain distributions that are conducive to the transmission of blue light and the transmission of red light, without interference with each other, and finally being coupled out by the first coupling-out grating 41 and the second coupling-out grating 42 to the human eye respectively, which is convenient for weakening ghost images; at the same time, the diffractive optical waveguide device 1 of the present application introduces the one-dimensional turning grating 300 to share the pupil expansion effect in the first half of the optical transmission path. On the premise of ensuring the separation of the two transmission optical paths, the premature introduction of the two-dimensional coupling-out grating is avoided, which may cause unnecessary coupling-out. It can improve the color uniformity to a certain extent while ensuring the efficiency of the optical waveguide.

[0059] Exemplarily, the grating period range of the first coupling-out grating 41 can be implemented as 310 nm to 330 nm, which is conducive to the transmission of blue light and green light; the grating period range of the second coupling-out grating 42 can be implemented as 410 nm to 430 nm, which is conducive to the transmission of red light and green light. In this way, the blue light step length transmitted through the first coupling-out grating 41 is basically the same as the red light step length transmitted through the second coupling-out grating 42, and in the transmission conditions of the diffractive optical waveguide device 1, there are not many corner cuts for red light and blue light, which can improve the color uniformity to a certain extent. It can be understood that in other examples of the present application, the grating period ranges of the first coupling-out grating 41 and the second coupling-out grating 42 can also be interchanged, and the present application will not elaborate on this.

[0060] For the convenience of description and understanding, the waveguide substrate 10 is hereinafter divided into two partitions in the up-down direction (i.e., the Y-axis direction) when the user wears it, that is, as Figure 2 and Figure 3 shown, the upper half partition 101 and the lower half partition 102; and the surface of the waveguide substrate 10 facing the user (i.e., the Z-axis direction) and the surface facing away from the user are respectively defined as the front surface 103 and the rear surface 104 as Figure 1 shown. The first turning grating 31 and the first coupling-out grating 41 are both located in the upper half partition 101 of the waveguide substrate 10, and the second turning grating 32 and the second coupling-out grating 42 are both located in the lower half partition 102 of the waveguide substrate 10. It can be understood that the X-axis direction of the present application refers to asFigure 2 The left - right direction, i.e., the arrangement direction of the coupling - in unit 20 and the coupling - out unit 40.

[0061] Optionally, the grating vector modulus of the first coupling - out grating 41 is greater than that of the second coupling - out grating 42, so that the transmission step of the blue light in the upper half - partition 101 is consistent with the transmission step of the red light in the lower half - partition 102, which is beneficial to improving color uniformity and minimizing ghost images as much as possible.

[0062] It should be noted that, in the first example of the present application, as Figures 1 to 3 shown, the coupling - in unit 20 is implemented as a two - dimensional coupling - in grating 21 disposed on the waveguide substrate 10, which is used to make the image light coupled into the waveguide substrate 10 transmit to the first turning grating 31 and the second turning grating 32 along two different up - down directions (i.e., the first coupling - in optical path 201 and the second coupling - in optical path 202) respectively.

[0063] Optionally, as Figure 3 shown, the two - dimensional coupling - in grating 21 has two grating vectors respectively along the first coupling - in optical path 201 and the second coupling - in optical path 202; and the grating vector modulus along the first coupling - in optical path 201 is greater than the grating vector modulus along the second coupling - in optical path 202. In this way, the transmission step of the blue light in the upper half - partition 101 and the transmission step of the red light in the lower half - partition 102 can be closer. Finally, the blue light emitted from the upper half - partition 101 and the red light emitted from the lower half - partition 102 do not deviate too much, further ensuring color uniformity while minimizing ghost images as much as possible.

[0064] Optionally, as Figure 2 and Figure 3 shown, the first turning grating 31 and the second turning grating 32 are arranged substantially symmetrically, so that the grating vector direction of the first turning grating 31 is approximately symmetric with the grating vector direction of the second turning grating 32, in order to receive the image light from the coupling - in unit 20 and transmit the image light from the upper and lower half - regions of the waveguide substrate 10 to the first coupling - out grating 41 and the second coupling - out grating 42 respectively.

[0065] Optionally, as Figures 1 to 3As shown, the two-dimensional coupling grating 21, the first turning grating 31, the second turning grating 32, the first output coupling grating 41, and the second output coupling grating 42 are all located on the front surface 103 of the waveguide substrate 10, where the first output coupling grating 41 and the second output coupling grating 42 are spliced together to completely cover the entire output coupling region. It can be understood that in other examples of this application, the first output coupling grating 41 and the second output coupling grating 42 may also be located on the front surface 103 and the rear surface 104 of the waveguide substrate 10 respectively, as long as they do not overlap in the front-back direction and can be spliced together. This application will not elaborate further on this.

[0066] Optionally, the angle between the grating vector of the first turning grating 31 and the X-axis is 120° + a + n * 180°; where a is the angle between the grating vector of the first output coupling grating 41 and the X-axis, and n is a positive integer.

[0067] It should be noted that the angle a between the grating vector of the first output coupling grating 41 of this application and the X-axis is determined by the grating vector component kfy1 of the half field of view angle in the Y direction in the K domain space, that is, a min = arcsin(|kyf1| / |kout1|) + 180°, and the value range of a is implemented as a min to a min + 2°, in order to ensure that a small field of view output light quantity is formed at the middle splicing position of the first output coupling grating 41 and the second output coupling grating 42.

[0068] Optionally, as Figure 5 shown, the two-dimensional coupling grating 21, the first output coupling grating 41, and the second output coupling grating 42 are all implemented as two-dimensional gratings distributed in a missing-corner rhombus shape.

[0069] Optionally, as Figure 6 shown, the first turning grating 31 and the second turning grating 32 are both implemented as one-dimensional blazed gratings.

[0070] Optionally, as Figure 4 shown, in each closed K domain, the grating vectors of the coupling unit 20, the turning unit 30, and the output coupling unit 40 form a closed regular triangle in the K space, where the grating periods represented by each regular triangle are equal, and the closed triangles in the upper and lower half regions both satisfy the K space transmission conditions of the diffractive optical waveguide.

[0071] Optionally, the refractive index of the waveguide substrate 10 is at least greater than 2.0. Preferably, the refractive index of the waveguide substrate 10 can simultaneously satisfy a blue light refractive index of 2.165, a green light refractive index of 2.125, and a red light refractive index of 2.091.

[0072] In summary, in the above first example of the present application: when the optical engine 2 projects image light in the visible light band onto the two-dimensional coupling grating 21 located on the front surface 103 of the waveguide substrate 10, under the action of two grating vectors of the two-dimensional coupling grating 21 along the first coupling optical path 201 and the second coupling optical path 202 respectively, the 0 field of view of the coupled light (i.e., the coupled image light) enters the waveguide substrate 10 and then propagates along the first coupling optical path 201 and then the second coupling optical path 202 in the upper half partition 101 and the lower half partition 102 of the waveguide substrate 10, so that the coupled light propagating in the upper half partition 101 and the coupled light propagating in the lower half partition 102 respectively propagate to the first turning grating 31 and the second turning grating 32, where the grating vector of the first turning grating 31 is as Figure 7 shown in the B direction, and the grating vector of the second turning grating 32 is as Figure 8 shown in the A direction; furthermore, the image light propagating along the first coupling optical path 201 and the second coupling optical path 202, after being acted on by the grating vectors of the first turning grating 31 and the second turning grating 32 respectively, continues to propagate independently in the upper half partition 101 and the lower half partition 102 of the waveguide substrate 10 to be transmitted to the first output grating 41 and the second output grating 42 respectively, where the grating vector of the first output grating 41 has the A direction and the B direction as Figure 7 shown, and the grating vector of the second output grating 42 has the A direction and the B direction as Figure 8 shown.

[0073] It should be noted that Figure 7 the grating vector in the A direction shown is used to couple out the image light from the first turning grating 31, and Figure 7 the grating vector in the B direction shown is used to expand the pupil of the image light from the first turning grating 31 in two-dimensional directions, that is, to expand the pupil upward; Figure 8 the grating vector in the B direction shown is used to couple out the image light from the second turning grating 32, and Figure 8 the grating vector in the A direction shown is used to expand the pupil of the image light from the second turning grating 32 in two-dimensional directions, that is, to expand the pupil downward.

[0074] In addition, the first type of linear change, the second type of linear change, and the third type of linear change shown by Figure 7 show all the iterative light generated by the action of the two-dimensional grating vector of the first output grating 41, where Figure 7 the meaning represented by the first type of linear change in is: the direction of the principal ray a1 (i.e., the effective ray a1) of the 0 field of view propagating to the first output grating 41 does not change. After acting on four K vectors b1 - b4 with different directions of the two-dimensional grating respectively, the change of the light line types c11 - c14 after diffraction; Figure 7The meaning represented by the second type of line pattern change in the [specific context] is as follows: After diffraction in the first type of line pattern change, the direction of the effective light ray a2 changes relative to the direction in the first type of line pattern change, but does not change in the second type of line pattern change. After the effective light ray a2 acts on four K vectors b1 - b4 with different directions on the two-dimensional grating respectively, the change in the line patterns c21 - c24 of the light after diffraction; Figure 7 The meaning represented by the third type of line pattern change in the [specific context] is as follows: After diffraction in the second type of line pattern change, the direction of the effective light ray a3 changes relative to the direction in the second type of line pattern change, but does not change in the third type of line pattern change. After the effective light ray a3 acts on four K vectors b1 - b4 with different directions on the two-dimensional grating respectively, the change in the line patterns c31 - c34 of the light after diffraction. It can be understood that, although Figure 7 it is easy to know that only the light wave vector c12 generated in the left second figure in the first type of line pattern change is slanting downwards, but from Figure 9 the K-space grating vector action diagram shown, the light wave vector c12 no longer meets the conditions of optical waveguide transmission and diffraction generation in the K domain, that is, this slanting downwards light does not exist, and the light in other directions will not be transmitted downwards. Therefore, no new light transmitted towards the lower half partition 102 will appear in the upper half partition 101 of the waveguide substrate 10 of the present application, avoiding interference of the light in the upper half partition 101 with the light in the lower half partition 102.

[0075] Similarly, from Figure 8 the first type of line pattern change, the second type of line pattern change, and the third type of line pattern change shown display all the iterative light generated by the action of the two-dimensional grating vectors of the second output grating 42. Among them Figure 8 the meaning represented by the first type of line pattern change in the [specific context] is as follows: The direction of the principal light ray d1 (i.e., the effective light ray d1) of the 0 field of view propagating to the second output grating 42 does not change. After acting on four K vectors e1 - e4 with different directions on the two-dimensional grating respectively, the change in the line patterns f11 - f14 of the light after diffraction; Figure 8 the meaning represented by the second type of line pattern change in the [specific context] is as follows: After diffraction in the first type of line pattern change, the direction of the effective light ray d2 changes relative to the direction in the first type of line pattern change, but does not change in the second type of line pattern change. After the effective light ray d2 acts on four K vectors e1 - e4 with different directions on the two-dimensional grating respectively, the change in the line patterns f21 - f24 of the light after diffraction; Figure 8 the meaning represented by the third type of line pattern change in the [specific context] is as follows: After diffraction in the second type of line pattern change, the direction of the effective light ray d3 changes relative to the direction in the second type of line pattern change, but does not change in the third type of line pattern change. After the effective light ray d3 acts on four K vectors e1 - e4 with different directions on the two-dimensional grating respectively, the change in the line patterns f31 - f34 of the light after diffraction. It can be understood that, although Figure 8It is easy to know that only the optical wave vector f12 generated by the left second figure in the first type of linear change is obliquely upward. However, since the second output grating 42 and the first output grating 41 are symmetrically arranged, the optical wave vector f12 no longer meets the conditions of optical waveguide transmission and diffraction generation in the K domain, that is, this obliquely upward light does not exist, and the light in other directions will not be transmitted upward. Therefore, no new light transmitted toward the upper half region 101 will appear in the lower half region 102 of the waveguide substrate 10 of the present application, avoiding interference of the light in the lower half region 102 with the light in the upper half region 101. In other words, there is no light crosstalk between the upper half region 101 and the lower half region 102 in the waveguide substrate 10, ensuring that the lights in the two K domain distributions that are beneficial to blue light transmission and beneficial to red light transmission are independently transmitted in the upper half region 101 and the lower half region 102 of the waveguide substrate 10, respectively, so as to well reduce ghost images.

[0076] It should be noted that the appendix Figure 10 shows a second example of the augmented reality device according to the above embodiment of the present application. Compared with the first example according to the present application, the augmented reality device according to the second example of the present application is different in that: the coupling unit 20 in the diffractive optical waveguide device 1 may include a first coupling grating 22 and a second coupling grating 23 disposed on the waveguide substrate 10, wherein both the first coupling grating 22 and the second coupling grating 23 are one-dimensional coupling gratings, and the first coupling grating 22 has a grating vector along the first coupling optical path 201 for coupling image light into the waveguide substrate 10 to be transmitted to the first turning grating 31, and the second coupling grating 23 has a grating vector along the second coupling optical path 202 for coupling image light into the waveguide substrate 10 to be transmitted to the second turning grating 32.

[0077] At the same time, in order to ensure that the image light projected by the optical engine 2 can be respectively propagated to the first coupling grating 22 and the second coupling grating 23, as Figure 10As shown, the augmented reality device may further include a semi-transmissive semi-reflective element 3 and a total reflection element 4. The semi-transmissive semi-reflective element 3 is disposed obliquely in the optical path between the optical engine 2 and the first coupling grating 22. The total reflection element 4 is disposed on the reflection side of the semi-transmissive semi-reflective element 3, and the second coupling grating 23 is located on the reflection side of the total reflection element 4. In this way, a part of the image light projected by the optical engine 2 is transmitted by the semi-transmissive semi-reflective element 3 to propagate to the first coupling grating 22 and is coupled into the waveguide substrate 10 by the first coupling grating 22. At the same time, another part of the image light projected by the optical engine 2 is first reflected by the semi-transmissive semi-reflective element 3 to propagate to the total reflection element 4, and then reflected by the total reflection element 4 to propagate to the second coupling grating 23 and is coupled into the waveguide substrate 10 by the second coupling grating 23. It can be understood that the semi-transmissive semi-reflective element 3 mentioned in the present application may but is not limited to be implemented as a semi-transmissive semi-reflective film, a BS prism or a PBS prism; the total reflection element 4 may but is not limited to be implemented as a plane mirror.

[0078] Optionally, in the second example of the present application, as Figure 10 shown, both the first coupling grating 22 and the second coupling grating 23 are located on the front surface 103 of the waveguide substrate 10, so that the coupling unit 20 forms a single-sided one-dimensional grating that can play a two-dimensional coupling role. Of course, in the third example of the present application, as Figure 11 shown, the first coupling grating 22 and the second coupling grating 23 may also be located on the front surface 103 and the rear surface 104 of the waveguide substrate 10 respectively, so that the coupling unit 20 forms a double-sided one-dimensional grating and can still play a two-dimensional coupling role.

[0079] It is worth mentioning that, according to another aspect of the present application, as Figure 12 shown, an embodiment of the present application further provides a method for designing an optical waveguide, which may include the steps of:

[0080] S100: Construct a first closed K domain conducive to the transmission of light in the first band in the upper half partition of the waveguide substrate in the K space; and

[0081] S200: Construct a second closed K domain conducive to the transmission of light in the second band different from the bandwidth of the light in the first band in the lower half partition of the waveguide substrate in the K space.

[0082] In this way, the first closed K domain and the second closed K domain are respectively located in the upper half partition and the lower half partition of the waveguide substrate in a mutually separated manner, so that the method for designing an optical waveguide of the present application can ensure that the light rays in the two constructed closed K domains can propagate independently respectively, so as to improve the color uniformity while minimizing the generation of ghost images.

[0083] Optionally, both the first closed K region and the second closed K region include the grating vectors of the coupling-in unit, the turning unit, and the coupling-out unit, where the grating vectors of the coupling-in unit, the turning unit, and the coupling-out unit in each closed K region form a closed equilateral triangle in the K space. In this way, the grating periods represented by each triangle are equal, and the closed triangles in the upper and lower half regions can satisfy the K space transmission conditions of the diffractive optical waveguide, which is beneficial to rapidly expand the pupil along the Y direction of the optical waveguide in the two-dimensional pupil expansion part, reduce the area size of the coupling-out region, and reduce the energy of premature coupling-out, so as to improve the overall efficiency of the optical waveguide.

[0084] Optionally, the first closed K region is conducive to transmitting blue light, the second closed K region is conducive to transmitting red light, and the grating vector modulus lengths of the coupling-in unit and the coupling-out unit in the first closed K region are both greater than those in the second closed K region, so that the transmission step length of blue light in the upper half partition is close to the transmission step length of red light in the lower half partition.

[0085] Optionally, the included angle between the coupling-out grating vector in the upper half partition of the waveguide substrate and the X axis is between amin and amin + 2°, where amin = arcsin(|kfy1| / |kout1|) + 180°, and arcsin represents the arcsine function; kfy1 represents the coupling-out grating vector; kout1 represents the grating vector component of the half field of view on the Y axis in the K domain space. It can be understood that the included angle a between the coupling-out grating vector kout1 in the upper half partition of the present application and the X axis is determined by the grating vector component kfy1 of the half field of view in the Y direction of the K domain space, and when the included angle a is between a min and a min + 2°, it can ensure the coupling-out light quantity of the small field of view at the middle splicing of the coupling-out grating.

[0086] Optionally, the included angle between the grating vector of the coupling-in unit and the X axis is a + 60°, where a is the included angle between the coupling-out grating vector in the upper half partition and the X axis. In this way, in the two-dimensional pupil expansion part, rapidly expanding the pupil along the Y direction of the optical waveguide can not only reduce the area size of the coupling-out region, but also reduce the energy of premature coupling-out, which helps to improve the overall efficiency of the optical waveguide.

[0087] Optionally, the distributions of the K vectors in the upper half partition of the waveguide substrate are symmetric about the X axis with respect to the distributions of the K vectors in the lower half partition of the waveguide substrate, so that the optical path transmissions in the upper and lower half regions are approximately symmetric, so as to independently transmit in the upper and lower half regions respectively under the principle of their respective K domains, and make the outer shapes of the grating regions in the upper and lower half regions established by this design method symmetrically distributed.

[0088] In summary, the optical waveguide design method of the present application, through the construction method of the double K domains in the upper and lower half regions, can not only achieve the purpose of preferentially transmitting blue light and red light in the upper and lower half regions respectively to improve the color uniformity of a single chip, but also can specifically weaken the ghost image problem that is extremely likely to occur due to the front and back overlap of the K domain regions in the conventional double K domain scheme for improving the color uniformity of a single chip.

[0089] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0090] The above embodiments only represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A diffractive optical waveguide device, characterized in that, Comprising: A waveguide substrate; An input coupling unit having a first input optical path and a second input optical path separated from each other, for coupling image light into the waveguide substrate in two paths to propagate along the first input optical path and the second input optical path respectively; A turning unit including a first turning grating disposed on the waveguide substrate and in the first input optical path and a second turning grating disposed on the waveguide substrate and in the second input optical path, both the first turning grating and the second turning grating being one-dimensional turning gratings; and An output coupling unit including a first output coupling grating disposed on the waveguide substrate and corresponding to the first turning grating and a second output coupling grating disposed on the waveguide substrate and corresponding to the second turning grating, the first output coupling grating and the second output coupling grating being non-overlapping two-dimensional output coupling gratings, and the grating period of the first output coupling grating being different from the grating period of the second output coupling grating.

2. The diffractive optical waveguide device according to claim 1, characterized in that The grating period of the first output coupling grating ranges from 310 nm to 330 nm; the grating period of the second output coupling grating ranges from 410 nm to 430 nm.

3. The diffractive optical waveguide device according to claim 2, wherein The grating vector modulus of the first output coupling grating is greater than the grating vector modulus of the second output coupling grating.

4. The diffractive optical waveguide device according to any one of claims 1 to 3, characterized in that, The input coupling unit is a two-dimensional input coupling grating disposed on the waveguide substrate; the two-dimensional input coupling grating has two grating vectors respectively along the first input optical path and the second input optical path, and the grating vector modulus along the first input optical path is greater than the grating vector modulus along the second input optical path.

5. The diffractive optical waveguide device according to claim 4, characterized in that, The two-dimensional input coupling grating, the first turning grating, the second turning grating, the first output coupling grating and the second output coupling grating are all located on the front surface of the waveguide substrate, wherein the first output coupling grating and the second output coupling grating are spliced with each other.

6. The diffractive optical waveguide device according to claim 4, wherein, The two-dimensional input coupling grating, the first output coupling grating and the second output coupling grating are all two-dimensional gratings distributed in a truncated rhombus shape; the first turning grating and the second turning grating are one-dimensional blazed gratings.

7. The diffractive optical waveguide device according to any one of claims 1 to 3, characterized in that, The input coupling unit includes a first input coupling grating and a second input coupling grating disposed on the waveguide substrate; wherein both the first input coupling grating and the second input coupling grating are one-dimensional input coupling gratings, and the first input coupling grating has a grating vector along the first input optical path, and the second input coupling grating has a grating vector along the second input optical path.

8. The diffractive optical waveguide device according to claim 7, characterized in that Both the first input coupling grating and the second input coupling grating are located on the front surface of the waveguide substrate; or, the first input coupling grating and the second input coupling grating are respectively located on the front surface or the back surface of the waveguide substrate.

9. The diffractive optical waveguide device according to any one of claims 1 to 3, characterized in that, The first turning grating and the second turning grating are symmetrically arranged; the included angle between the grating vector of the first turning grating and the X-axis is 120° + a + n * 180°, where a is the included angle between the grating vector of the first output coupling grating and the X-axis, and n is a positive integer.

10. The diffractive optical waveguide device according to any one of claims 1 to 3, characterized in that, The grating vectors of the input coupling unit, the turning unit and the output coupling unit form a closed equilateral triangle in the K space.

11. An augmented reality device, characterized in that, Comprising: An optical engine; And The diffractive optical waveguide device according to any one of claims 1 to 10 is disposed on the light output side of the optical engine and is used to transmit image light from the optical engine.

12. The augmented reality device according to claim 11, characterized in that, It further includes a semi-reflective and semi-transmissive element and a total reflection element. The semi-reflective and semi-transmissive element is disposed obliquely in the optical path between the optical engine and the first coupling grating of the diffractive optical waveguide device. The total reflection element is disposed on the reflection side of the semi-reflective and semi-transmissive element, and the second coupling grating of the diffractive optical waveguide device is located on the reflection side of the total reflection element.

13. A method for designing an optical waveguide, characterized in that, It includes steps: Constructing a first closed K domain facilitating the transmission of light in the first band in the upper half partition of the waveguide substrate in the K space; and Constructing a second closed K domain facilitating the transmission of light in the second band with a bandwidth different from that of the light in the first band in the lower half partition of the waveguide substrate in the K space.

14. The optical waveguide design method according to claim 13, characterized in that Both the first closed K domain and the second closed K domain include the grating vectors of the coupling unit, the grating vectors of the turning unit, and the grating vectors of the coupling-out unit. Among them, the grating vectors of the coupling unit, the grating vectors of the turning unit, and the grating vectors of the coupling-out unit in each closed K domain form a closed equilateral triangle in the K space.

15. The optical waveguide design method according to claim 13, characterized in that The first closed K domain facilitates the transmission of blue light, the second closed K domain facilitates the transmission of red light, and the magnitudes of the grating vectors of the coupling unit and the coupling-out unit in the first closed K domain are both greater than the magnitudes of the grating vectors in the second closed K domain.

16. The optical waveguide design method according to claim 15, wherein The included angle between the coupling grating vector in the upper half partition of the waveguide substrate and the X-axis is between a min and a min + 2°, where a min = arcsin(|kfy1| / |kout1|) + 180°, arcsin represents the arcsine function; kfy1 represents the coupling grating vector; kout1 represents the grating vector component on the Y-axis of the half field of view in the K domain space.

17. The optical waveguide design method according to claim 16, wherein The included angle between the grating vector of the coupling unit and the X-axis is a + 60°, where a is the included angle between the coupling-out grating vector in the upper half partition and the X-axis.

18. The optical waveguide design method according to claim 13, wherein The distributions of the respective K vectors in the upper half partition of the waveguide substrate are symmetric about the X-axis with respect to the distributions of the respective K vectors in the lower half partition of the waveguide substrate.

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