Light guide device, optical module and head-mounted display equipment

Abstract

The embodiment of the invention provides a light guide device, an optical module and head-mounted display equipment. The light guide device comprises a substrate, a coupling-in region and a coupling-out region, wherein the coupling-in region and the coupling-out region are arranged on the substrate; the coupling-in area is used for coupling light into the substrate and enabling the light to be totally reflected and transmitted to the coupling-out area; wherein the light is coupled into the coupling area at different incident angles; the coupling-out area is used for expanding and coupling out light rays propagating in the substrate; the coupling-in region and / or the coupling-out region comprise / comprises a two-dimensional super grating structure; the two-dimensional super grating structure comprises at least one two-dimensional grating, and a grating period of a single two-dimensional grating comprises at least two units, so that the diffraction efficiency of a target diffraction order of the two-dimensional grating can be regulated and controlled, and the adjustable and controllable range of the diffraction efficiency can be increased.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical technology, and more specifically, to a light guide device, an optical module, and a head-mounted display device. Background Art

[0002] Augmented Reality (AR) technology is an optical display composed of a micro display and optical elements. Without affecting the user's observation of the external environment, the image generated by the micro display is projected into the user's eyes, realizing the superposition and fusion of the real world and virtual images. It has great application prospects in education, entertainment, industry and other fields.

[0003] At present, diffraction optical waveguide is one of the mainstream technical solutions for realizing augmented reality. It uses the diffraction effect of micro-nano structures to couple in and out light, and combines the total reflection effect of transparent substrates to conduct light. In existing solutions, two-dimensional gratings are usually applied to waveguides as out-coupling elements to achieve two-dimensional pupil expansion and out-coupling of light. However, the two-dimensional grating itself is used as a pupil expansion and out-coupling element, and the existence of multiple diffraction orders at the same time leads to low overall out-coupling efficiency when it is used as an out-coupling element, and there are problems of diffraction energy loss and light leakage when pointing to the non-human eye side, resulting in information leakage. Summary of the invention

[0004] The purpose of this application is to provide a new technical solution for a light-guiding device, an optical module and a head-mounted display device.

[0005] In a first aspect, an embodiment of the present application provides a light guide device. The light guide device includes a substrate and an incoupling region and an outcoupling region disposed on the substrate;

[0006] The coupling-in region is used to couple light into the substrate and cause the light to be totally reflected and propagated to the coupling-out region; wherein the light is coupled into the coupling-in region at different incident angles;

[0007] The outcoupling region is used to expand and outcouple the light propagating in the substrate;

[0008] The outcoupling region includes a two-dimensional supergrating structure, which includes at least one two-dimensional grating, and a grating period of a single two-dimensional grating contains at least two units, which can achieve the diffraction efficiency of the target diffraction order of the two-dimensional grating and increase the adjustable range of the diffraction efficiency.

[0009] Optionally, a single two-dimensional grating is a columnar two-dimensional grating with a parallelogram or rhombus cross section, and the at least two units are arranged at intervals in the single two-dimensional grating;

[0010] By regulating at least one of the number, shape, size and position of the units, the diffraction efficiency of the corresponding target diffraction order of the two-dimensional grating can be improved or suppressed.

[0011] Optionally, a single grating period of the two-dimensional grating includes at least two units to form an asymmetric diffraction structure, so that light can form an asymmetric diffraction behavior when encountering the two-dimensional grating.

[0012] Optionally, the two-dimensional supergrating structure comprises a plurality of the two-dimensional gratings arranged in an array;

[0013] Wherein, a grating period of a single two-dimensional grating includes at least two units, and the units are arranged obliquely or vertically relative to the substrate.

[0014] Optionally, a grating period of a single two-dimensional grating includes a first unit and a second unit, and the first unit and the second unit are arranged at intervals in the single two-dimensional grating.

[0015] Optionally, a grating period of a single two-dimensional grating includes a first unit, a second unit and a third unit, and the first unit, the second unit and the third unit are arranged at intervals in the single two-dimensional grating.

[0016] Optionally, a coupling element is provided in the coupling-in area, and light with different incident angles diffracts after being incident on the coupling-in element. After the diffracted light propagates to the decoupling area, at least two light propagation paths are formed at the position of the decoupling area according to different diffraction orders: one of the light propagation paths is coupled out of the substrate to form an image outside the substrate through the decoupling area, and the other light propagation path is continued to propagate after the pupil is expanded through the decoupling area.

[0017] Optionally, the coupling-in element is a diffractive optical element, including a one-dimensional grating and / or the two-dimensional supergrating structure.

[0018] In a second aspect, an embodiment of the present application provides an optical module. The optical module includes the light guide device as described in the first aspect; and

[0019] An optical machine is used to project light into the light guiding device.

[0020] In a third aspect, an embodiment of the present application provides a head mounted display device. The head mounted display device comprises:

[0021] A front frame assembly including at least one lens mounting portion;

[0022] a wearing assembly, detachably connected to the front frame assembly; and

[0023] An optical module as described in the second aspect; wherein, the light guide device is disposed in the lens mounting portion, the optical engine is disposed on the front frame component and is located on a side close to the wearing component, and the optical engine is opposite to the coupling area.

[0024] The beneficial effects of this application are:

[0025] According to an embodiment of the present application, a diffraction optical solution for display is provided, and a two-dimensional supergrating structure is designed for application in a decoupling zone. Compared with a conventional two-dimensional grating, the two-dimensional supergrating structure contains at least two units in each grating period. By increasing the number of units in each grating period, the diffraction efficiency of certain specific diffraction orders among the multiple diffraction orders of the two-dimensional grating can be reasonably regulated, and the light energy loss in the decoupling zone can be reduced. This design is conducive to providing a higher overall decoupling efficiency.

[0026] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0028] Figure 1 One of the structural schematic diagrams of the two-dimensional supergrating structure provided in the embodiment of the present application;

[0029] Figure 2 for Figure 1 A top view of

[0030] Figure 3 The second structural schematic diagram of the two-dimensional supergrating structure provided in the embodiment of the present application;

[0031] Figure 4 for Figure 3 A top view of

[0032] Figure 5 The third structural schematic diagram of the two-dimensional supergrating structure provided in the embodiment of the present application;

[0033] Figure 6 for Figure 5 A top view of

[0034] Figure 7 The fourth structural schematic diagram of the two-dimensional supergrating structure provided in the embodiment of the present application;

[0035] Figure 8 for Figure 7 A top view of

[0036] Fig. 9 A fifth structural diagram of a two-dimensional supergrating structure provided in an embodiment of the present application;

[0037] Fig.10 for Fig. 9 A top view of

[0038] Fig.11 The sixth structural diagram of the two-dimensional supergrating structure provided in the embodiment of the present application;

[0039] Fig.12 for Fig.11 A top view of

[0040] Fig.13 The seventh structural diagram of the two-dimensional supergrating structure provided in the embodiment of the present application;

[0041] Fig.14 for Fig.13 A top view of

[0042] Fig.15 It is the diffraction efficiency diagram of different diffraction orders of conventional two-dimensional grating;

[0043] Fig.16 One of the diffraction efficiency diagrams of different diffraction orders of the two-dimensional supergrating structure provided in the embodiment of the present application;

[0044] Fig.17 The second diffraction efficiency diagram of different diffraction orders of the two-dimensional supergrating structure provided in the embodiment of the present application;

[0045] Fig.18 A diagram of the light propagation path of light coupled into the light guiding device provided in an embodiment of the present application.

[0046] Description of reference numerals:

[0047] 1. Two-dimensional grating; 2. Unit; 21. First unit; 22. Second unit; 23. Third unit; 3. Substrate; 4. Outcoupling region; 01. Human eye. DETAILED DESCRIPTION

[0048] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0049] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0050] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0051] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0052] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0053] The light guide device, optical module and head-mounted display device provided in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0054] According to one embodiment of the present application, a light guide device is provided. Fig.18 The light guide device includes a substrate 3 and a coupling-in region ( Fig.18 The coupling-in region is used to couple light into the substrate 3 and cause the light to be totally reflected and propagated to the coupling-out region 4; wherein the light is coupled into the coupling-in region at different incident angles. The coupling-out region 4 is used to expand and couple out the light propagating in the substrate 3. Figures 1 to 14 The outcoupling region 4 includes a two-dimensional supergrating structure, which includes at least one two-dimensional grating 1, and a single two-dimensional grating 1 contains at least two units 2 within a grating period, which can achieve the diffraction efficiency of the target diffraction order of the two-dimensional grating 1 and increase the adjustable range of the diffraction efficiency.

[0055] According to the light-guiding device provided in the above-mentioned embodiment, a two-dimensional supergrating structure is introduced in the out-coupling region 4. Compared with the conventional two-dimensional grating, an additional unit 2 is introduced in each grating period of the two-dimensional supergrating structure, so that the grating period of a single two-dimensional grating 1 can contain two or more units 2 in total.

[0056] Conventional two-dimensional gratings have multiple different diffraction orders. When conventional two-dimensional gratings are used as pupil expansion and outcoupling elements, the simultaneous presence of multiple diffraction orders results in low overall outcoupling efficiency, and there are problems of energy loss and information leakage caused by diffracted light on the side not pointing to the human eye.

[0057] In the embodiment of the present application, a specially designed two-dimensional supergrating structure is used in the outcoupling region 4, wherein the grating period of a single two-dimensional grating 1 may include two or more units 2 in total, and by introducing additional units 2, the diffraction efficiency of a specific diffraction order of the two-dimensional grating 1 may be regulated, which enables the two-dimensional grating to have more degrees of freedom in the design of the diffraction efficiency of a specific diffraction order. Moreover, a larger range of diffraction efficiency regulation may be achieved.

[0058] For example, the diffraction efficiency of a specific diffraction order of a conventional two-dimensional grating can only be adjusted within a range of 20% to 80%. However, the two-dimensional supergrating structure provided in the embodiment of the present application can achieve a wider range of diffraction efficiency adjustment than 20% to 80%. For example, the two-dimensional supergrating structure can be used to achieve a diffraction efficiency adjustment between 1% and 99%, which achieves a wider range of diffraction efficiency adjustment.

[0059] According to the two-dimensional supergrating structure provided in the above embodiments, it can be applied to a diffractive optical waveguide or other types of diffractive optical elements.

[0060] For example, the two-dimensional supergrating structure can be applied to diffraction light waveguide lenses.

[0061] When the two-dimensional supergrating structure is applied to the diffraction optical waveguide lens and designed at a selected position in the outcoupling zone 4, the diffraction efficiency of certain diffraction orders can be improved and the diffraction efficiency of other diffraction orders can be suppressed by adjusting the diffraction efficiency of specific diffraction orders, so that the light energy of the entire outcoupling zone 4 can be more reasonably distributed to reduce the energy loss of the outcoupling light in the outcoupling zone 4, which is conducive to providing a higher overall outcoupling efficiency. Thereby, the diffraction performance of the outcoupling zone 4 can be optimized.

[0062] Optionally, the two-dimensional supergrating structure can be mass-produced using general lithography and etching, or nanoimprinting technology.

[0063] According to an embodiment of the present application, a diffraction optical solution for display is provided, and a two-dimensional supergrating structure (2D metagrating) is designed and applied to the decoupling area. Compared with a conventional two-dimensional grating, each grating period of the two-dimensional supergrating structure contains at least two units. By increasing the number of units in each grating period, the diffraction efficiency of certain specific diffraction orders among the multiple diffraction orders of the two-dimensional grating can be reasonably regulated, and the light energy loss in the decoupling area can be reduced. This design is conducive to providing a higher overall decoupling efficiency.

[0064] See also Fig.15 , Fig.15 shows the diffraction efficiency diagram of different diffraction orders of a conventional two-dimensional grating, see Fig.15It can be seen that conventional two-dimensional gratings have multiple diffraction orders, resulting in energy loss and light leakage.

[0065] See also Fig.16 , a two-dimensional supergrating structure is provided, in which unit 2 is placed at a selected position to suppress the diffraction efficiency of the 1,1 order and improve the diffraction efficiency of the -1,1 order.

[0066] See also Fig.17 , a two-dimensional supergrating structure is provided, in which unit 2 is placed at a selected position to suppress the diffraction efficiency of the 0, 2 order and improve the diffraction efficiency of the -1, 1 order.

[0067] In some examples of this application, see Figures 1 to 14 , a single two-dimensional grating 1 is a columnar two-dimensional grating with a parallelogram or rhombus cross section, and the at least two units 2 are arranged at intervals in the single two-dimensional grating 1. By regulating at least one of the number, shape, size and position of the units 2, the diffraction efficiency of the target diffraction order of the corresponding two-dimensional grating 1 can be improved or suppressed.

[0068] In the present application, the unit 2 is added within the grating period of a single two-dimensional grating 1. When the unit 2 is added, it is necessary to design the number, shape, size and specific setting position of the unit 2 according to the diffraction efficiency of the diffraction order to be adjusted. These factors will affect the diffraction efficiency of certain diffraction orders.

[0069] The two-dimensional supergrating structure provided in the embodiment of the present application enables the two-dimensional grating to have a higher degree of freedom in designing the diffraction efficiency of different diffraction orders, and a wider range of regulating the diffraction efficiency. Compared with conventional two-dimensional gratings, the two-dimensional supergrating structure can provide more flexible diffraction efficiency.

[0070] Optionally, the shape of the unit 2 includes a triangle, a trapezoid or a polygon.

[0071] The shapes of the units 2 included in the grating period of a single two-dimensional grating 1 can be designed as required.

[0072] In some examples of the present application, a single two-dimensional grating 1 includes at least two units 2 in a grating period to form an asymmetric diffraction structure, so that light can form an asymmetric diffraction behavior when encountering the two-dimensional grating 1.

[0073] According to the above example, a single two-dimensional grating 1 contains at least two units 2 in its grating period. Different diffraction structures can be formed by designing each unit 2 differently. In this way, when light encounters the two-dimensional supergrating structure, it can form different diffraction behaviors in different dimensions, thereby forming an asymmetric diffraction response, which can regulate the light energy distribution in the outcoupling zone 4.

[0074] The two-dimensional supergrating structure provided in the embodiment of the present application can provide higher diffraction efficiency and asymmetric diffraction response for different incident light angles compared to conventional two-dimensional gratings.

[0075] In some examples of the present application, the two-dimensional supergrating structure includes a plurality of the two-dimensional gratings 1 arranged in an array; wherein a single two-dimensional grating 1 contains at least two units 2 in a grating period, and the units 2 are arranged obliquely or vertically relative to the substrate 3.

[0076] Optionally, see Figures 1 to 8 The two-dimensional supergrating structure includes at least one two-dimensional grating 1. The grating period of a single two-dimensional grating 1 includes a first unit 21 and a second unit 22, and the first unit 21 and the second unit 22 are arranged at intervals in the single two-dimensional grating 1.

[0077] For example, see Figure 1 and Figure 2 The two-dimensional supergrating structure includes multiple two-dimensional gratings 1, wherein the grating period of a single two-dimensional grating 1 contains two units 2 with the same height and width.

[0078] For example, see Figure 3 and Figure 4 The two-dimensional supergrating structure includes multiple two-dimensional gratings 1, wherein the grating period of a single two-dimensional grating 1 contains two units 2 with the same width but different heights.

[0079] For example, see Figure 5 and Figure 6 The two-dimensional supergrating structure includes multiple two-dimensional gratings 1, wherein the grating period of a single two-dimensional grating 1 contains two units 2 with the same height but different widths.

[0080] For example, see Figure 7 and Figure 8 The two-dimensional supergrating structure includes multiple two-dimensional gratings 1, wherein the grating period of a single two-dimensional grating 1 contains two units 2 with different heights and different widths.

[0081] That is to say, the two units 2 included in the grating period of a single two-dimensional grating 1 may be completely identical, or different, or partially identical, and the specific adjustment may be made according to the situation.

[0082] Optionally, see Figures 9 to 14 The two-dimensional supergrating structure includes at least one two-dimensional grating 1. The grating period of a single two-dimensional grating 1 includes a first unit 21, a second unit 22 and a third unit 23, and the first unit 21, the second unit 22 and the third unit 23 are arranged at intervals in the single two-dimensional grating 1.

[0083] In fact, the two-dimensional grating 1 may include more than three units 2 within the grating period.

[0084] See also Fig. 9 and Fig.10 The grating period of a single two-dimensional grating 1 includes three or more units 2 of the same or different shapes and the same or different heights. For example, the grating period of a single two-dimensional grating 1 includes three units 2 of different shapes and different heights.

[0085] See also Fig.11 and Fig.12 The grating period of a single two-dimensional grating 1 may also include three or more units 2 of the same or different shapes, the same or different heights and inclinations. For example, the grating period of a single two-dimensional grating 1 includes three units 2 of different shapes, different heights and all inclinations.

[0086] See also Fig.13 and Fig.14 The grating period of a single two-dimensional grating 1 may also include three or more units 2 of the same or different shapes, the same or different heights, and the shapes of triangles, trapezoids or polygons.

[0087] According to the light-guiding device provided in the embodiment of the present application, the two-dimensional supergrating structure may be used in the entire out-coupling region 4, or the two-dimensional supergrating structure may be used partially. When the two-dimensional supergrating structure is used partially in the out-coupling region 4, a two-dimensional grating and / or a one-dimensional grating may be introduced in the out-coupling region 4, combined with the two-dimensional supergrating structure, and a partition may be formed in the out-coupling region 4.

[0088] By introducing the two-dimensional supergrating structure provided in the embodiment of the present application into the outcoupling region, the light energy in the entire outcoupling region can be distributed more flexibly and reasonably, which can improve the diffraction efficiency of the outcoupling region and thus improve the imaging quality.

[0089] In some examples of this application, see Fig.18A coupling element is arranged in the coupling-in area, and light with different incident angles diffracts after being incident on the coupling-in element. After the diffracted light propagates to the decoupling area 4, at least two light propagation paths are formed at the position of the decoupling area 4 according to different diffraction orders: one of the light propagation paths is coupled out of the substrate 3 through the decoupling area 4 to form an image, and the other light propagation path is continued to propagate after the pupil is expanded through the decoupling area 4.

[0090] See also Fig.18 In the outcoupling area 4 , the light A coupled out to the outside of the substrate 3 presents an image in the human eye 01 , and the light B that continues to propagate after pupil expansion continues to be transmitted in the substrate 3 .

[0091] In addition, please continue to see Fig.18 , and part of the light C causes light energy leakage loss on the non-human eye side.

[0092] In some examples of the present application, the coupling-in element is a diffractive optical element including a one-dimensional grating and / or the two-dimensional supergrating structure.

[0093] When the two-dimensional supergrating structure is used in the coupling-in region, the coupling-in efficiency can be adjusted.

[0094] According to the light-guiding device provided in the embodiment of the present application, it can be, for example, a diffraction light waveguide, which can be suitable for application in wearable devices, wherein the wearable devices include head mounted display devices (Head mounted display, HMD), such as AR head mounted display devices.

[0095] When the light guide device is a diffractive optical waveguide, the substrate 3 is a waveguide substrate. Of course, the light guide device can also be a diffractive optical element in other forms.

[0096] For the diffraction efficiencies of different diffraction orders of conventional two-dimensional gratings, see Fig.15 , providing a symmetrical diffraction response. Conventional two-dimensional gratings have multiple diffraction orders, which can easily lead to energy loss and light leakage.

[0097] The two-dimensional supergrating structure provided in the embodiment of the present application can provide an asymmetric diffraction response. Fig.16 and Fig.17 , shows a two-dimensional supergrating structure, in which unit 2 is placed at a selected position, which can suppress the 0, 2nd order diffraction efficiency and improve the -1, 1st order diffraction efficiency.

[0098] Taking the two-dimensional supergrating structure provided in the embodiment of the present application as an example for the outcoupling region, a higher overall outcoupling efficiency can be provided. The diffraction efficiency of a specific order can be improved or suppressed simply by adjusting the shape, size, and position of each unit within the two-dimensional supergrating period.

[0099] According to another embodiment of the present application, an optical module is provided.

[0100] The optical module includes the light guide device and an optical machine as described above; wherein the optical machine is used to project light into the light guide device.

[0101] The imaging light emitted by the optical machine can cover the entire coupling area.

[0102] The imaging light emitted by the optical machine may be monochromatic light or polychromatic light.

[0103] The optical module provided in the embodiments of the present application can be used in, for example, a head-mounted display device, specifically in AR glasses or an AR helmet.

[0104] According to another embodiment of the present application, a head-mounted display device is provided, the head-mounted display device comprising a front frame assembly, including at least one lens mounting portion;

[0105] a wearing assembly, detachably connected to the front frame assembly; and

[0106] The optical module as described above; wherein the light guide device is arranged in the lens mounting portion, the optical machine is arranged on the front frame component and is located on a side close to the wearing component, and the optical machine is opposite to the coupling area.

[0107] The front frame component is, for example, a frame or a main body of a helmet, and the wearing component is, for example, a temple or a strap.

[0108] The specific implementation of the light guide device and the optical module of the embodiment of the present application can refer to the above-mentioned light guide device embodiments, so it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0109] The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0110] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may 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 guide device, characterized in that: It comprises a substrate (3) and a coupling-in region and a coupling-out region (4) arranged on the substrate (3); The coupling-in region is used to couple light into the substrate (3) and cause the light to be totally reflected and propagated to the coupling-out region (4); wherein the light is coupled into the coupling-in region at different incident angles; The outcoupling region (4) is used to expand and outcouple the light propagating in the substrate (3); The outcoupling region (4) comprises a two-dimensional supergrating structure, wherein the two-dimensional supergrating structure comprises at least one two-dimensional grating (1), and a grating period of a single two-dimensional grating (1) comprises at least two units (2), so that the diffraction efficiency of a target diffraction order of the two-dimensional grating (1) can be regulated and the adjustable range of the diffraction efficiency can be increased.

2. The light guide device according to claim 1, characterized in that: The single two-dimensional grating (1) is a columnar two-dimensional grating with a parallelogram or rhombus cross section, and the at least two units (2) are arranged at intervals in the single two-dimensional grating (1); By regulating at least one of the number, shape, size and position of the units (2), the diffraction efficiency of the target diffraction order of the corresponding two-dimensional grating (1) can be improved or suppressed.

3. The light guide device according to claim 1, characterized in that: A single two-dimensional grating (1) contains at least two units (2) in a grating period to form an asymmetric diffraction structure, so that light can form an asymmetric diffraction behavior when encountering the two-dimensional grating (1).

4. The light guide device according to claim 1, characterized in that: The two-dimensional supergrating structure comprises a plurality of the two-dimensional gratings (1) arranged in an array; Wherein, a single two-dimensional grating (1) comprises at least two units (2) within a grating period, and the units (2) are arranged obliquely or vertically relative to the substrate (3).

5. The light guide device according to any one of claims 1 to 4, characterized in that: A grating period of a single two-dimensional grating (1) comprises a first unit (21) and a second unit (22), and the first unit (21) and the second unit (22) are arranged at intervals in the single two-dimensional grating (1).

6. The light guide device according to any one of claims 1 to 4, characterized in that: The grating period of a single two-dimensional grating (1) comprises a first unit (21), a second unit (22) and a third unit (23); the first unit (21), the second unit (22) and the third unit (23) are arranged at intervals in the single two-dimensional grating (1).

7. The light guide device according to claim 1, characterized in that: A coupling element is arranged in the coupling-in area, and light rays with different incident angles are incident on the coupling-in element and diffracted. After the diffracted light rays propagate to the decoupling area (4), at least two light propagation paths are formed at the position of the decoupling area (4) according to different diffraction orders: one of the light propagation paths is coupled out of the substrate (3) through the decoupling area (4) to form an image, and the other light propagation path is continued to propagate after the pupil is expanded through the decoupling area (4).

8. The light guide device according to claim 7, characterized in that: The coupling-in element is a diffractive optical element, including a one-dimensional grating and / or the two-dimensional supergrating structure.

9. An optical module, characterized in that: include: The light guide device according to any one of claims 1 to 8; as well as An optical machine is used to project light into the light guiding device.

10. A head mounted display device, characterized in that: include: A front frame assembly including at least one lens mounting portion; A wearing component, detachably connected to the front frame component; as well as, The optical module as claimed in claim 9; wherein the light guide device is disposed in the lens mounting portion, the optical machine is disposed on the front frame component and is located on a side close to the wearing component, and the optical machine is opposite to the coupling area.

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