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

Abstract

Some embodiments of the present application provide a light guide device, an optical module, and a head-mounted display device. The light guide device comprises a light guide substrate, and an in-coupling region and an out-coupling region which are provided on the light guide substrate; the out-coupling region is used for carrying out pupil expansion and out-coupling on light from the in-coupling region; the out-coupling region comprises at least one first strip grating having grooves; and at least two grooves are provided and are respectively arranged in two opposite sides of the first strip grating, and the grooves can be used for increasing the order of diffraction of the first strip grating and forming a target diffraction efficiency corresponding to the order of diffraction, so that the light transmitted to the position of the first strip grating can be transformed from being diffracted on a single side of the first strip grating to being diffracted on both sides of the first strip grating. According to the solution provided by the embodiments of the present application, light energy can be reasonably distributed in the out-coupling region, and the light efficiency and the imaging quality can be improved.

Description

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

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on June 29, 2023, with application number 202310790430.7 and invention name “A light guide device, optical module and head-mounted display device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The embodiments of the present application relate to the field of optical imaging technology. More specifically, the embodiments of the present application relate to a light guide device, an optical module, and a head-mounted display device. Background Art

[0003] Existing diffractive waveguide solutions feature separate in-coupling and out-coupling regions on the waveguide plate. All gratings within the out-coupling region have a consistent structure, resulting in consistent diffraction efficiency for out-coupling light at different locations within the out-coupling region. However, since the total energy of the light is constant, the energy at the edges and tail of the out-coupling region decreases as the light propagates, leading to lower energy for the out-coupling light. This results in uneven image intensity and low overall optical efficiency.

[0004] Summary of the Invention

[0005] 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, so as to achieve different diffraction efficiencies in different areas within the outcoupling zone.

[0006] In a first aspect, the present application provides a light guide device. The light guide device includes a light guide substrate and an incoupling region and an outcoupling region disposed on the light guide substrate;

[0007] The outcoupling region is used to expand the pupil of the light from the incoupling region and couple it out;

[0008] The outcoupling region includes at least one first strip grating with grooves, and the grooves are provided in at least two numbers and are located on opposite sides of the first strip grating. The grooves can be used to increase the diffraction order of the first strip grating and form a target diffraction efficiency corresponding to the diffraction order, so that light propagating to the position of the first strip grating can be transformed from being originally diffracted on one side of the first strip grating to being able to increase diffraction on the other side of the first strip grating.

[0009] Optionally, the outcoupling region includes a plurality of mutually independent sub-outcoupling regions;

[0010] A plurality of the first strip gratings are provided and are located in at least one of the sub-outcoupling regions to form a transition grating region between the two-dimensional grating region and the one-dimensional grating region.

[0011] Optionally, in one of the sub-outcoupling regions, a plurality of the first strip gratings are provided;

[0012] The plurality of first strip gratings are adjacent and spaced apart to form a partitioned arrangement in the sub-outcoupling region; or the plurality of first strip gratings are adjacent and sequentially connected to form a whole in the sub-outcoupling region.

[0013] Optionally, the width of the first strip grating is L, and the groove depth of the groove is ≤ L;

[0014] When the groove depth is L, the groove penetrates the first strip grating in the width direction of the first strip grating, so that the diffraction efficiency of the added diffraction order on the other side of the first strip grating reaches a maximum value.

[0015] Optionally, the groove includes a groove bottom and a groove wall extending from the groove bottom;

[0016] The groove wall includes a first surface and a second surface opposite to each other, the first surface forms a first angle A1 with the groove bottom, the second surface forms a second angle A2 with the groove bottom, and the first angle A1 and the second angle A2 are 0° to 180°;

[0017] The angle between the groove bottom and the side of the first strip grating along the length direction is 0° to 89°;

[0018] The dimensions of the first surface and the second surface along the width direction of the first stripe grating are 0 to 1000 nm.

[0019] Optionally, the plurality of sub-outcoupling regions include a two-dimensional grating region and a one-dimensional grating region;

[0020] Wherein, the two-dimensional grating region is located in the middle of the outcoupling region;

[0021] The one-dimensional grating region is provided with at least two and is disposed on two opposite sides of the two-dimensional grating region; the transition grating region is located between the two-dimensional grating region and the one-dimensional grating region.

[0022] Optionally, the two-dimensional grating region includes a plurality of parallelogram gratings, and the plurality of parallelogram gratings are arranged to form a first target shape;

[0023] The one-dimensional grating region includes a plurality of second strip gratings, and the second strip gratings do not have the grooves. The plurality of second strip gratings are arranged to form a second target shape.

[0024] Optionally, the outcoupling region is provided on a surface of the light-guiding substrate;

[0025] In the outcoupling region: the two opposite sides of the grating structure form an angle with the surface of the light-guiding substrate, and the angle is 20° to 160°; or the grating structure is a step grating

[0026] In a second aspect, the present application provides an optical module. The optical module includes:

[0027] The light guide device according to the first aspect; and

[0028] An optical machine is used to project light or an image into the light guide device.

[0029] In a third aspect, the present application provides a head-mounted display device. The head-mounted display device includes:

[0030] a housing; and

[0031] The optical module as described in the second aspect.

[0032] The beneficial effects of this application are:

[0033] According to the light-guiding device provided in the embodiment of the present application, which is a diffraction light waveguide solution, a strip grating with grooves is introduced into the outcoupling region, and the strip grating has grooves on opposite sides. The introduction of the grooves increases the diffraction order of the strip grating, which can break the original one-dimensional grating characteristics of the strip grating and form a transitional grating structure between a two-dimensional grating and a one-dimensional grating. When used in the outcoupling region, it is beneficial to reasonably distribute the light energy in the outcoupling region, and the final imaging picture quality is good and the optical efficiency is high.

[0034] 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

[0035] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only part of the drawings of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without any creative work.

[0036] FIG1 is a top view of a light guide device according to an embodiment of the present application;

[0037] FIG2 is a second top view of the light guide device provided in an embodiment of the present application;

[0038] FIG3 is a top view of the outcoupling zone design of the light guide device provided in an embodiment of the present application;

[0039] FIG4 is a diagram showing the pupil expansion effect when two-dimensional gratings are set in all out-coupling areas without partitioning;

[0040] FIG5 is a schematic structural diagram of a first stripe grating provided in an embodiment of the present application;

[0041] FIG6 is a schematic diagram of another structure of the first stripe grating provided in an embodiment of the present application;

[0042] FIG7 is a schematic diagram of another structure of the first stripe grating provided in an embodiment of the present application;

[0043] FIG8 is a schematic diagram of another structure of the first stripe grating provided in an embodiment of the present application;

[0044] FIG9 is a schematic diagram of a structure of a groove provided in an embodiment of the present application;

[0045] FIG10 is a second schematic diagram of the structure of the groove provided in an embodiment of the present application;

[0046] FIG11 is a schematic diagram of a structure of a groove provided in an embodiment of the present application;

[0047] FIG12 is another schematic diagram of the structure of the groove provided in an embodiment of the present application;

[0048] FIG13 is another structural diagram of the groove provided in the embodiment of the present application

[0049] FIG14 is a side view of the light guide device provided in an embodiment of the present application.

[0050] Explanation of the accompanying drawings: 1. Light-guiding substrate; 2. Coupling-in region; 3. Coupling-out region; 31. First strip grating; 311. Side; 301. Two-dimensional grating region; 302. One-dimensional grating region; 303. Transition grating region; 4. Groove; 41. Groove bottom; 42. First surface; 43. Second surface; 01. First light ray; 02. Second light ray; 03. Third light ray; 1001. First diffraction light ray; 1002. Second diffraction light ray; 1003. First outcoupled light ray; 1004. Third diffraction light ray; 1005. Second outcoupled light ray. DETAILED DESCRIPTION

[0051] 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 arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0052] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0053] 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.

[0054] 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.

[0055] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0056] The light guide device, optical module and head-mounted display device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0057] According to one aspect of an embodiment of the present application, a light guide device is provided. The light guide device is, for example, a diffractive light waveguide solution, which can be suitable for use in a wearable device. The wearable device includes a head mounted display (HMD), such as an augmented reality (AR) head mounted display.

[0058] The specific form of the head-mounted display device includes, for example, smart glasses or a smart helmet, etc. The specific form of the head-mounted display device is not limited in the embodiments of the present application.

[0059] According to one embodiment of the present application, a light guide device is provided, as shown in Figures 1 and 2. The light guide device includes a light guide substrate 1 and an incoupling region 2 and an outcoupling region 3 disposed on the light guide substrate 1. The outcoupling region 3 is used to expand the pupil of light from the incoupling region 2 and outcouple it; the outcoupling region 3 includes at least one first strip grating 31 with grooves 4, and the grooves 4 are provided in at least two numbers and are disposed on opposite sides of the first strip grating 31. The grooves 4 can be used to increase the diffraction order of the first strip grating 31 and form a target diffraction efficiency corresponding to the diffraction order, so that light propagating to the position of the first strip grating 31 can be transformed from being diffracted on one side of the first strip grating 31 to being diffracted on the other side of the first strip grating 31.

[0060] According to the above-mentioned embodiment of the present application, the light guide device is, for example, a diffraction optical waveguide solution, which can be applied to the field of augmented reality technology, etc. A coupling grating is provided in the coupling-in region 2. The coupling-in grating can be, for example, a hologram or a photonic crystal, and can be used to couple external light, such as light projected by an optical machine, into the light guide substrate 1, and enable the coupled-in light to be totally reflected within the light guide substrate 1 and propagate to the coupling-out region 3. The coupling-out region 3 has the function of expanding the pupil and coupling out light.

[0061] The outcoupling region 3 is designed to have at least one first strip grating 31 with grooves 4. The appearance of the first strip grating 31 can be seen in Figures 1 and 2. By introducing grooves on opposite sides of the strip grating, the original one-dimensional grating characteristics of the strip grating can be broken, so that light can be diffracted on both sides of the strip grating after entering the grooved strip grating.

[0062] It should be noted that for the first stripe grating 31, the diffraction efficiency of the newly added diffraction order is related to the layout of the grooves 4 on the first stripe grating 31 and / or the shape of the grooves 4 themselves. The shape of the grooves 4 is primarily affected by the groove depth and width. The diffraction efficiency of the newly added diffraction order can differ from the diffraction efficiency of the original diffraction order. For example, the diffraction efficiency of the newly added diffraction order can be lower than the diffraction efficiency of the original diffraction order.

[0063] According to the light-guiding device provided in the embodiment of the present application, the outcoupling region 3 can adopt a partitioned design, wherein a first strip grating 31 with grooves 4 is provided in at least one sub-region. The diffraction performance of the first strip grating 31 is between that of a two-dimensional grating and a one-dimensional grating. Referring to Figures 1 to 3, a transition grating between the two-dimensional grating and the one-dimensional grating is formed in the outcoupling region 3. The application of this transition grating in the outcoupling region 3 can form more reasonable and fine partitions in the outcoupling region 3, and the light after pupil expansion forms a more reasonable light energy distribution in the outcoupling region 3, which is conducive to improving imaging quality.

[0064] For example, referring to Figures 1 and 2, the first light 01 from the coupling-in area 2 propagates to the coupling-out area 3 in a state of total reflection within the light-guiding substrate 1. The first light 01 undergoes diffraction at the position of the first strip grating 31, and forms a second light 02 according to the original diffraction order of the first strip grating 31. In addition, the first strip grating 31 also adds a third light 03 because it has a groove 4. The third light 03 is directly related to the groove 4 on the first strip grating 31. The shape of the groove 4 and the layout on the first strip grating 31 can be designed in advance as needed to adjust the diffraction efficiency of the newly added diffraction order. This is conducive to a more reasonable adjustment of the diffraction behavior of the pupil expansion light in the coupling-out area 3, a reasonable distribution of light energy, and improved light efficiency.

[0065] Referring to Figure 4, Figure 4 illustrates the optical behavior of an unpartitioned outcoupling zone 3, which is designed as a two-dimensional grating. The incoupling zone 2 in Figure 4 is used to receive light projected by an external optical machine and couple the light into the light-guiding substrate, generating a first diffracted ray 1001 that propagates toward the outcoupling zone 3, i.e., the two-dimensional grating. Upon impacting the outcoupling zone 3, the first diffracted ray 1001 propagates in both directions, producing a second diffracted ray 1002. The first outcoupling ray 1003 continues to propagate in the original direction. Upon impacting the outcoupling zone 3 again, the second diffracted ray 1002 generates a third diffracted ray 1004 and a second outcoupling ray 1005. The diffraction direction of the third diffracted ray 1004 is the same as that of the first diffracted ray 1001, and the second diffracted ray 1002 continues to propagate in the original direction. When the first diffracted ray 1001 and the third diffracted ray 1004 and other light rays impact the outcoupling zone 3, outcoupled diffracted rays are generated, while continuing to propagate forward. Since all the grating structures in the outcoupling region 3 shown in FIG4 have the same shape, the efficiency of the outcoupling behavior of the first outcoupling light 1003, the second outcoupling light 1005 and other identical light rays is consistent. The inability to adjust the light energy distribution in the outcoupling region may result in the light energy not being truly and effectively utilized, thereby reducing the optical efficiency.

[0066] The light-guiding device provided in the embodiment of the present application improves the decoupling region 3. By introducing a first strip grating 31 with a groove 4 into the decoupling region 3, this design enhances the diffraction order of the strip grating, so that the strip grating is transformed from being able to diffract light only on one side to being able to diffract light on both sides, and the diffraction efficiency on both sides is different, thus forming a transition grating between a two-dimensional grating and a one-dimensional grating, thereby achieving the effect of rationally distributing light in the decoupling region 3.

[0067] According to the light-guiding device provided in the embodiment of the present application, it is a diffraction light waveguide solution. By introducing at least one first strip grating 31 with grooves 4 into the outcoupling region 3, and the first strip grating 31 has one or more grooves 4 on opposite sides, the introduction of the grooves 4 increases the diffraction order of the first strip grating 31, which can break the original one-dimensional grating characteristics of the strip grating, forming a transitional grating structure between a two-dimensional grating and a one-dimensional grating. When used in the outcoupling region 3, it is beneficial to reasonably distribute the light energy in the outcoupling region 3, and the final imaging picture quality is good and the optical efficiency is high.

[0068] It should be emphasized that the traditional strip grating exhibits the characteristics of a one-dimensional grating. However, after providing at least one groove 4 on it, the characteristics of the original one-dimensional grating can be broken, so that the first strip grating 31 provided with the groove 4 can have a diffraction order in another direction, thereby allowing the light to be diffracted in two different directions. This optical behavior can enhance the energy of the light in the other direction.

[0069] In the light guide device provided in the embodiment of the present application, the coupling-in region 2 and the coupling-out region 3 may be located on the same surface of the light guide substrate 1, or may be located on two opposite surfaces of the light guide substrate 1. In other words, the coupling-in region 2 and the coupling-out region may be placed on the upper surface or the lower surface of the light guide substrate in any arrangement or combination, and this application does not impose any restrictions on this.

[0070] The light-guiding device provided in the embodiments of the present application is, for example, a diffraction waveguide, wherein the diffraction grating in the coupling-in region 2 and the diffraction grating in the coupling-out region 3 may form a closed grating vector polygon. The coupling-in region 2 may be composed of a single one-dimensional or two-dimensional grating, or multiple one-dimensional or two-dimensional gratings. The coupling-out region 3 may be composed of a single two-dimensional grating, or multiple one-dimensional or two-dimensional gratings.

[0071] The direction of the one-dimensional grating vector is perpendicular to its grating lines and is the direction of its periodic change. Its length is equal to the inverse of the grating period. The two-dimensional grating is periodically distributed in both the horizontal and vertical directions.

[0072] In some examples of the present application, referring to FIG3 , the outcoupling region 3 includes a plurality of mutually independent sub-outcoupling regions; a plurality of the first strip gratings 31 are provided and are located in at least one of the sub-outcoupling regions to form a transition grating region 303 between the two-dimensional grating region and the one-dimensional grating region.

[0073] According to the above example, the decoupling region 3 is designed as a partitioned region, which may include multiple sub-decoupling regions, and these sub-decoupling regions may be identical or different. At least one of the multiple sub-decoupling regions includes a certain number of first strip gratings 31 with grooves 4, resulting in diffraction performance between that of a two-dimensional grating region and a one-dimensional grating region. In this way, within the decoupling region 3, the light energy after pupil expansion can be more reasonably distributed, thereby improving the optical efficiency of the entire light-guiding device.

[0074] When the groove 4 is provided on the first strip grating 31, by designing the groove depth and / or groove width of the groove 4, the diffraction efficiency ratio of the newly added diffraction order on the other side of the first strip grating 31 can be designed, thereby ultimately achieving the purpose of rationally utilizing light energy.

[0075] According to the above example, within the outcoupling region 3 , one or more sub-outcoupling regions including the first strip grating 31 may be provided, and this is not limited in the embodiment of the present application.

[0076] In some examples of the present application, within a sub-coupling region, the first strip grating 31 is set as a plurality; wherein, referring to FIG1 , the plurality of first strip gratings 31 are adjacent and spaced apart to form a partitioned arrangement within the sub-coupling region; or, referring to FIG2 , the plurality of first strip gratings 31 are adjacent and sequentially connected to form a whole within the sub-coupling region.

[0077] For example, referring to the right side of FIG. 1 , a sub-outcoupling region within the outcoupling region 3 is shown. Three first strip gratings 31 may be provided in the sub-outcoupling region, for example, and intervals are provided between adjacent first strip gratings 31 , that is, each first strip grating 31 is independent, and each first strip grating 31 is provided with a plurality of grooves 4 on opposite sides along the length direction.

[0078] For another example, referring to the right side of FIG. 2 , a sub-outcoupling region within the outcoupling region 3 is shown, in which three first strip gratings 31 are provided. Adjacent first strip gratings 31 are interconnected, and each first strip grating 31 is provided with a plurality of grooves 4 on opposite sides along the length direction. Ultimately, all the first strip gratings 31 within the sub-outcoupling region form a diamond-shaped appearance.

[0079] In some examples of the present application, the width of the first strip grating 31 is L, and the groove depth of the groove 4 is ≤ L; when the groove depth of the groove 4 is L, the groove 4 penetrates the first strip grating 31 in the width direction of the first strip grating 31, so that the diffraction efficiency of the increased diffraction order on the other side of the first strip grating 31 reaches the maximum value.

[0080] The deeper the groove 4, the higher the diffraction efficiency of the newly added diffraction orders on the other side of the first strip grating 31 having the groove 4. When the groove 4 completely extends across the width of the first strip grating 31, the diffraction efficiency of the newly added diffraction orders reaches its maximum value.

[0081] It should be noted that when the groove depth of the groove 4 is 0, that is, no groove is formed on the first strip grating 31, the first strip grating 31 thus maintains the diffraction characteristics of a one-dimensional grating.

[0082] In the case where a plurality of grooves 4 are provided on the first strip grating 31 , the plurality of grooves 4 are designed to be arranged at intervals along the length direction of the first strip grating 31 , and the plurality of grooves 4 are arranged on opposite sides of the strip grating 31 , see FIG. 5 to FIG. 7 .

[0083] The grooves 4 on both sides of the first strip grating 31 can be symmetrically arranged, including axial symmetry and central symmetry. Of course, the grooves 4 on both sides of the first strip grating 31 can also be asymmetrically arranged. This allows for greater design freedom in the transition grating region.

[0084] Optionally, for the first strip grating 31 with the groove 4, further grooves may be formed in the groove 4, as shown in FIG6 and FIG7 , which provides more ways to adjust the diffraction efficiency.

[0085] 8 , when a plurality of grooves 4 are provided on the strip grating 31 , the plurality of grooves 4 are spaced apart along the length direction of the first strip grating 31 , and the plurality of grooves 4 may also be located on the same side of the first strip grating 31 .

[0086] In some examples of the present application, referring to Figure 9, the groove 4 includes a groove bottom 41 and a groove wall extending from the groove bottom 41; wherein, referring to Figure 10, the groove wall includes a first surface 42 and a second surface 43 opposite to each other, the first surface 42 forms a first angle A1 with the groove bottom 41, and the second surface 43 forms a second angle A2 with the groove bottom 41, and the first angle A1 and the second angle A2 are 0° to 180; the angle between the groove bottom 41 and the side 311 of the first strip grating 31 along the length direction is 0° to 89°.

[0087] 10 , the size of the first surface 42 and the second surface 43 along the width direction of the first stripe grating 31 is 0-1000 nm.

[0088] For example, referring to FIG11 , a shape of the groove 4 is shown, wherein the first angle A1 is 120°, the second angle A2 is 60°, and the angle between the groove bottom 41 and the side 311 of the first strip grating 31 along the length direction is 0°.

[0089] For another example, referring to FIG12 , another shape of the groove 4 is shown, wherein the first angle A1 is 60°, the second angle A2 is 90°, and the angle between the groove bottom 41 and the side 311 of the first strip grating 31 along the length direction is 0°.

[0090] For another example, referring to FIG. 13 , another shape of the groove 4 is shown, wherein the first surface 42 is parallel to the second surface 43 , and the angle between the groove bottom 324 and the side 311 of the first strip grating 31 along the length direction is 30°.

[0091] It should be emphasized that the arrangement of the grooves 4 is mainly to increase the diffraction orders of the strip grating. Grooves of different shapes and numbers will affect the diffraction efficiency of the newly added diffraction orders of the strip grating.

[0092] In an example of the present application, referring to FIG3 , the multiple sub-outcoupling regions include a two-dimensional grating region 301 and a one-dimensional grating region 302; wherein the two-dimensional grating region 301 is located in the middle of the outcoupling region 3; the one-dimensional grating region 302 is set to at least two and is arranged on opposite sides of the two-dimensional grating region 301; the transition grating region 303 is located between the two-dimensional grating region 301 and the one-dimensional grating region 302.

[0093] According to the above example, the two-dimensional grating region 301 includes a plurality of parallelogram gratings, and the plurality of parallelogram gratings are arranged to form a first target shape; the one-dimensional grating region 302 includes a plurality of second strip gratings, and the second strip gratings do not have the grooves 4, and the plurality of second strip gratings are arranged to form a second target shape.

[0094] The outcoupling zone 3 needs to have both pupil expansion and outcoupling functions. According to the above example, the outcoupling zone 3 includes different types of gratings arranged in zones, and a transition grating zone with diffraction behavior intermediate between the two-dimensional grating zone and the one-dimensional grating zone is introduced between them. The transition grating zone is a two-dimensional grating structure design that can improve optical performance.

[0095] Referring to Figure 3, a two-dimensional grating is set at the center of the outcoupling area 3 to perform two-dimensional pupil expansion on the central field of view light, and a one-dimensional grating is used at the outer edge of the outcoupling area 3 to couple the light out, and a first strip grating 31 with grooves 4 is used in the transition area from the center to the edge to perform the transition of the diffraction behavior, so that the light energy of the entire outcoupling area 3 forms a reasonable transition from the central field of view to the edge field of view, so that the light energy in the outcoupling area 3 can be reasonably distributed, which can improve the light efficiency.

[0096] In an example of the present application, referring to FIG14 , the outcoupling region 3 is provided on a surface of the light-guiding substrate 1; within the outcoupling region 3: the opposite sides of the grating structure form angles A and B with the surface of the light-guiding substrate 1, respectively, and the angles are 20° to 160°; or, the grating structure is a step grating.

[0097] According to the grating structure design of the outcoupling area in the above example, an anti-light leakage effect can be formed in the outcoupling area 3, which can provide users with a better immersive experience.

[0098] According to another aspect of an embodiment of the present application, an optical module is provided, comprising the light guide device described above and an optical engine, wherein the optical engine is configured to project light or an image into the light guide device.

[0099] The light energy in the entire outcoupling zone 3 can be distributed more flexibly and reasonably from the middle to the edge, forming a gradual transition of light energy in the outcoupling zone 3, which can improve the diffraction efficiency of the outcoupling zone 3 and thus improve the imaging quality.

[0100] The imaging light emitted by the optical engine should be able to cover the entire coupling-in area 2 .

[0101] The imaging light emitted by the optical machine can be monochromatic light or polychromatic light.

[0102] According to another aspect of the embodiments of the present application, a head-mounted display device is provided, comprising a housing and the optical module as described above.

[0103] The head-mounted display device is, for example, an AR head-mounted device, including AR glasses or an AR helmet, etc., and the embodiments of the present application do not impose specific restrictions on this.

[0104] The specific implementation of the optical module and head-mounted display device of the embodiments of the present application can refer to the above-mentioned embodiments of the light guide device, and therefore at least have all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0105] 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.

[0106] 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 for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above examples 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 light-guiding substrate (1) and an incoupling region (2) and an outcoupling region (3) arranged on the light-guiding substrate (1); The outcoupling area (3) is used to expand the pupil of the light from the incoupling area (2) and couple it out; The outcoupling region (3) comprises at least one first strip grating (31) with grooves (4), and the grooves (4) are arranged in at least two and are arranged on two opposite sides of the first strip grating (31). The grooves (4) can be used to increase the diffraction order of the first strip grating (31) and form a target diffraction efficiency corresponding to the diffraction order, so that light propagating to the position of the first strip grating (31) can be transformed from the original single-side diffraction on the first strip grating (31) to the additional diffraction on the other side of the first strip grating (31).

2. The light guide device according to claim 1, characterized in that: The outcoupling region (3) comprises a plurality of mutually independent sub-outcoupling regions; A plurality of the first stripe gratings (31) are provided and are located in at least one of the sub-outcoupling regions to form a transition grating region (303) between a two-dimensional grating region and a one-dimensional grating region.

3. The light guide device according to claim 2, characterized in that: In one outcoupling sub-region, the first stripe grating (31) is arranged in plurality; The plurality of first strip gratings (31) are arranged adjacently and at intervals to form a partitioned arrangement in the sub-coupling area; or The plurality of first strip gratings (31) are adjacent and sequentially connected to form a whole in the sub-coupling region.

4. The light guide device according to any one of claims 1 to 3, characterized in that: The width of the first strip grating (31) is L, and the depth of the groove (4) is ≤ L; When the groove depth of the groove (4) is L, the groove (4) penetrates the first strip grating (31) in the width direction of the first strip grating (31), so that the diffraction efficiency of the increased diffraction order on the other side of the first strip grating (31) reaches a maximum value.

5. The light guide device according to any one of claims 1 to 3, characterized in that: The groove (4) comprises a groove bottom (41) and a groove wall extending from the groove bottom (41); The groove wall comprises a first surface (42) and a second surface (43) opposite to each other, the first surface (42) and the groove bottom (41) form a first angle A1, the second surface (43) and the groove bottom (41) form a second angle A2, the first angle A1 and the second angle A2 are 0° to 180°; The angle between the groove bottom (41) and the side edge (311) of the first strip grating (31) along the length direction is 0° to 89°; The sizes of the first surface (42) and the second surface (43) along the width direction of the first stripe grating (31) are 0 to 1000 nm.

6. The light guide device according to claim 2, characterized in that: The plurality of sub-outcoupling regions include a two-dimensional grating region (301) and a one-dimensional grating region (302); Wherein, the two-dimensional grating region (301) is located in the middle of the outcoupling region (3); The one-dimensional grating area (302) is provided in at least two portions and is disposed on two opposite sides of the two-dimensional grating area (301); The transition grating region (303) is located between the two-dimensional grating region (301) and the one-dimensional grating region (302).

7. The light guide device according to claim 6, characterized in that: The two-dimensional grating region (301) comprises a plurality of parallelogram gratings, and the plurality of parallelogram gratings are arranged to form a first target shape; The one-dimensional grating region (302) includes a plurality of second strip gratings, and the second strip gratings do not have the grooves (4), and the plurality of second strip gratings are arranged to form a second target shape.

8. The light guide device according to claim 1, characterized in that: The outcoupling region (3) is arranged on a surface of the light-guiding substrate (1); In the outcoupling region (3), two opposite sides of the grating structure respectively form an angle with the surface of the light-guiding substrate (1), and the angle is 20° to 160°; or, the grating structure is a step grating.

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 or an image into the light guiding device.

10. A head mounted display device, characterized in that: include: a housing; and The optical module as claimed in claim 9.

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