Light guide device, optical module and head-mounted display equipment
By introducing a transition grating region into the coupling region of the light guide device and adjusting the rotation angle of the second grating, the problem of uneven light energy distribution in the prior art is solved, and more efficient imaging and optical efficiency are achieved.
Patent Information
- Application Number
- CN202311010555.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-10
- Publication Date
- 2025-02-18
AI Technical Summary
The existing diffraction optical waveguide schemes have uneven distribution of light energy in the coupling area, resulting in uneven image intensity and low optical efficiency.
A transition grating region is introduced in the coupling region of the light guide device, and the second grating rotates a preset angle with respect to the first grating to adjust the light intensity of the diffraction order of the light ray and reasonably allocate the light energy in the coupling region.
By reasonably distributing light energy, the quality of imaging images and optical efficiency are improved.
Smart Images
Figure CN119471889A_ABST
Abstract
Description
Technical Field
[0001] 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
[0002] In the existing diffraction waveguide solution, a coupling-in region and a coupling-out region are respectively arranged on the waveguide plate. At present, the structure of all gratings in the coupling-out region is consistent, so the diffraction efficiency of the coupled-out light at different positions in the coupling-out region is consistent. Since the total energy of the light is constant, as the light is transmitted, the energy of the light at the edge and tail positions in the coupling-out region will become lower and lower, and the energy of the coupled-out light will also become lower and lower, resulting in uneven image intensity and low overall optical efficiency. Summary of the invention
[0003] 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.
[0004] In a first aspect, the present application provides a light guide device. The light guide device comprises a light guide substrate and an incoupling region and an outcoupling region arranged on the light guide substrate;
[0005] The outcoupling region is used to expand the pupil of the light from the incoupling region and couple it out;
[0006] The outcoupling region includes a two-dimensional grating region and a transition grating region;
[0007] The two-dimensional grating region is located in the middle of the outcoupling region, and the transition grating regions are provided in at least two portions and are disposed on two opposite sides of the two-dimensional grating region;
[0008] The two-dimensional grating region includes a first grating, and the transition grating region includes a second grating. Both the first grating and the second grating can realize double-sided diffraction of light propagating thereto. The second grating is rotated at a preset angle relative to the first grating on the surface of the light-guiding substrate to adjust the light intensity of at least one side diffraction order of light propagating to the position of the second grating.
[0009] Optionally, the first grating includes a plurality of first grating units, the second grating includes a plurality of second grating units, and the first grating units and the second grating units have the same shape;
[0010] In the second grating unit and the first grating unit corresponding to each other, the second grating unit is rotated by a preset angle on the surface of the light guide substrate relative to the first grating unit.
[0011] Optionally, the second grating is rotated at a preset angle relative to the first grating on the surface of the light guide substrate to weaken the intensity of the diffraction orders of the light propagating to the position of the second grating and away from the two-dimensional grating area.
[0012] Optionally, the first grating modulates the first light propagated thereto into a second light and a third light, the second light is transmitted close to the two-dimensional grating area, and the third light is transmitted away from the two-dimensional grating area;
[0013] The light intensity of the second light is equal to the light intensity of the third light.
[0014] Optionally, the second grating modulates the first light propagating thereto into a second light and a third light, the second light is transmitted close to the two-dimensional grating area, and the third light is transmitted away from the two-dimensional grating area;
[0015] The light intensity of the third light is less than the light intensity of the second light.
[0016] Optionally, the first grating is a symmetrical structure.
[0017] Optionally, the preset angle is 30° to 85°.
[0018] Optionally, the outcoupling region further includes a one-dimensional grating region, the one-dimensional grating region includes at least two and is located at two opposite sides of the two-dimensional grating region, and the transition grating region is located between the two-dimensional grating region and the one-dimensional grating region.
[0019] Optionally, the one-dimensional grating region includes a plurality of third grating units, and the third grating units are long strip gratings.
[0020] Optionally, the outcoupling region further includes a one-dimensional grating region, the one-dimensional grating region includes at least two and is located at two opposite sides of the two-dimensional grating region, and the transition grating region is located between the two-dimensional grating region and the one-dimensional grating region;
[0021] The one-dimensional grating region includes a plurality of third grating units, and the third grating units are long strip gratings.
[0022] Optionally, the first grating unit and the third grating unit have the same width, and in the vector direction of the third grating unit, the grating lines of the first grating unit are parallel.
[0023] Optionally, the outcoupling region is provided on a surface of the light-guiding substrate;
[0024] In the outcoupling region, two opposite sides of the grating structure form angles with the surface of the light-guiding substrate, and the angles are 20° to 160°; or, the grating structure is a step grating.
[0025] In a second aspect, the present application provides an optical module. The optical module comprises:
[0026] The light guide device according to the first aspect; and
[0027] An optical machine is used to project light or an image into the light guiding device.
[0028] In a third aspect, the present application provides a head mounted display device. The head mounted display device comprises:
[0029] a housing; and
[0030] An optical module as described in the second aspect.
[0031] The beneficial effects of this application are:
[0032] According to the light-guiding device provided in the embodiment of the present application, which is a diffraction light waveguide solution, a transition grating area is introduced in the out-coupling area, wherein the second grating in the transition grating area is rotated by a preset angle relative to the first grating. Without reducing the diffraction order of the first grating, the light intensity of at least one side of the diffraction order of the light transmitted to the transition grating area is adjusted, so that the light energy in the out-coupling area can be reasonably distributed, and the final imaging picture quality is good and the optical efficiency is high.
[0033] 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
[0034] 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.
[0035] Figure 1 The pupil expansion effect diagram of setting two-dimensional gratings in the out-coupling area without partitioning.
[0036] Figure 2 This is one of the top views of the light guide device provided in the embodiment of the present application.
[0037] Figure 3 This is the second top view of the light guide device provided in the embodiment of the present application.
[0038] Figure 4 A schematic diagram of the grating structure in the transition grating region provided in an embodiment of the present application.
[0039] Figure 5 A schematic diagram of a grating structure in a two-dimensional grating region provided in an embodiment of the present application.
[0040] Figure 6A schematic diagram of a grating structure in a one-dimensional grating region provided in an embodiment of the present application.
[0041] Figure 7 A structural relationship diagram of the first grating unit and the third grating unit provided in an embodiment of the present application.
[0042] Figure 8 A schematic diagram of the structure of the first grating unit provided in the embodiment of the present application Figure 1 .
[0043] Fig. 9 A schematic diagram of the structure of the first grating unit provided in the embodiment of the present application Figure 2 .
[0044] Fig.10 A side view of a light guide device provided in an embodiment of the present application.
[0045] Description of reference numerals:
[0046] 1. Light-guiding substrate;
[0047] 2. Coupling zone;
[0048] 3. outcoupling region; 30. two-dimensional grating region; 31. one-dimensional grating region; 32. transition grating region;
[0049] 301, first grating; 3011, first grating unit; 311, second grating; 3111, second grating unit; 3211, third grating unit;
[0050] 01, first light; 02, second light; 03, third light;
[0051] 1001, first diffraction light; 1002, second diffraction light; 1003, first outcoupled light; 1004, third diffraction light; 1005, second outcoupled light.
[0052] 41. First baseline; 42. Second baseline. DETAILED DESCRIPTION
[0053] 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.
[0054] 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.
[0055] 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.
[0056] 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.
[0057] 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.
[0058] 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.
[0059] According to one aspect of an embodiment of the present application, a light guide device is provided, wherein the light guide device is, for example, a diffraction light waveguide solution, which can be suitable for application in a wearable device. The wearable device includes a head mounted display (HMD), such as an AR head mounted display device.
[0060] 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.
[0061] According to one embodiment of the present application, a light guide device is provided. Figure 2-Figure 6 The light guide device comprises: a light guide substrate 1 and a coupling-in region 2 and a coupling-out region 3 arranged on the light guide substrate 1 .
[0062] The outcoupling area 3 is used to expand the pupil of the light from the incoupling area 2 and couple it out.
[0063] The outcoupling region 3 includes a two-dimensional grating region 30 and a transition grating region 32 .
[0064] The two-dimensional grating region 30 is located in the middle of the outcoupling region 3 , and at least two transition grating regions 32 are provided and are disposed on two opposite sides of the two-dimensional grating region 30 .
[0065] The two-dimensional grating region 30 includes a first grating 301, and the transition grating region 32 includes a second grating 311. Both the first grating 301 and the second grating 311 can realize double-sided diffraction of light propagating thereto;
[0066] The second grating 311 is rotated at a preset angle relative to the first grating 301 on the surface of the light guide substrate 1 to adjust the light intensity of at least one side diffraction order of the light propagating to the position of the second grating 311 .
[0067] According to an embodiment of the present application, a light guide device is provided. The light guide device may be a diffraction light waveguide solution, which may be applied to the field of augmented reality technology, etc. Among them, a coupling-in grating is arranged in the coupling-in area 2, and the coupling-in grating may be, for example, a hologram or a photonic crystal, etc., which may 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 in the light guide substrate 1 and propagate to the coupling-out area 3. The coupling-out area 3 has the function of expanding the pupil and coupling out light.
[0068] The outcoupling region 3 includes a two-dimensional grating region 30 located in the middle of the outcoupling region 3 and transition grating regions 32 located on both sides of the two-dimensional grating region 30 . Therefore, the outcoupling region 3 is divided into regions, and different grating structures are correspondingly arranged in different regions.
[0069] Specifically, the outcoupling region 3 includes a two-dimensional grating region 30, and the two-dimensional grating region 30 includes a first grating 301. The grating structure of the first grating 301 is a two-dimensional grating, and the two-dimensional grating has vector directions in two directions, and the two-dimensional grating is periodically distributed in both directions. The first grating 301 can realize double-sided diffraction of light propagating thereto.
[0070] The outcoupling region 3 includes a transition grating region 32, which includes at least two transition grating regions 32 and are respectively located on opposite sides of the two-dimensional grating region 30. Specifically, the transition grating region 32 is arranged away from the middle of the outcoupling region 3 relative to the two-dimensional grating region 30. The outcoupling region 3 has a relatively strong symmetry with respect to the FOV, and the transition grating region 32 is also symmetrically arranged with respect to the two-dimensional grating region 30.
[0071] The transition grating region 32 includes a second grating 311. The second grating 311 can realize bilateral diffraction of the light propagating thereto, and the intensity of the light diffracted on both sides is inconsistent. Specifically, the light transmitted to the second grating 311 is modulated to form diffracted light in different diffraction directions, and the diffracted light in different diffraction directions has different light intensities.
[0072] For example, the second grating 311 is rotated at a preset angle relative to the first grating 301 on the surface of the waveguide substrate, so that after the light is transmitted to the second grating 311, the light intensity of at least one diffraction order of the light propagated to the position of the second grating 311 is adjusted. For example, the light propagated to the position of the second grating 311 is modulated into diffracted light diffracted in two directions, and the light intensity of the diffracted light in these two directions can be weakened at the same time, or the light intensity of the diffracted light in one direction can be strengthened and the light intensity of the diffracted light in the other direction can be weakened, or the light intensity of the diffracted light in one direction can be unchanged and the light intensity of the diffracted light in the other direction can be weakened.
[0073] It should be noted that, for the second grating 311, the second grating 311 modulates the light transmitted thereto so that the modulated light has different light intensities, which is related to the rotation angle of the second grating 311 relative to the first grating 301. For example, the second grating 311 rotates at different angles relative to the first grating 301, and after the second grating 311 adjusts the light transmitted thereto, the modulated light can have different light intensities, so that the light intensity distribution of the light in the outcoupling area 3 is reasonable. For example, according to the change in the position of the light in the outcoupling area 3, the diffraction efficiency ratio of different diffraction orders is strengthened or weakened, and finally the purpose of rationally utilizing the light energy is achieved.
[0074] Reference Figure 1 , providing an optical behavior of the outcoupling region 3 in the prior art without partitioning. The outcoupling region 3 is designed as a two-dimensional grating. Figure 1 The coupling-in area 2 is used to receive the light projected by the external optical machine, and couple the light into the light-guiding substrate 1, generating a first diffraction light 1001 that propagates toward the coupling-out area 3, i.e., the two-dimensional grating direction. When the first diffraction light 1001 is incident on the coupling-out area 3, it will propagate the second diffraction light 1002 to both sides, and the first coupling-out light 1003 will continue to propagate along the original direction. When the second diffraction light 1002 is incident on the coupling-out area 3 again, a third diffraction light 1004 and a second coupling-out light 1005 will be generated, wherein the diffraction direction of the third diffraction light 1004 is the same as that of the first diffraction light 1001, and the second diffraction light 1002 will continue to propagate along the original direction. When the first diffraction light 1001 and the third diffraction light 1004 and other light rays are incident on the coupling-out area 3, coupled-out diffraction light is generated, and at the same time, it continues to propagate forward. Due to Figure 1 All grating structures in the outcoupling area 3 shown have the same shape, so the efficiency of the first outcoupling light 1003, the second outcoupling light 1005 and other identical light outcoupling behaviors are consistent. Failure to adjust the light energy distribution in the outcoupling area 3 may result in the light energy not being truly and effectively utilized, thereby reducing the optical efficiency.
[0075] The light-guiding device provided in the embodiment of the present application improves the decoupling zone 3, specifically, the decoupling zone 3 is divided into zones. The second grating 311 arranged in the transition grating zone 32 is rotated by a preset angle relative to the first grating 301. For example, the first grating 301 can be rotated around any point of the first grating 301 to obtain the second grating 311. The second grating 311 is a transition grating between a two-dimensional grating and a one-dimensional grating. The second grating 311 increases the diffraction order relative to the one-dimensional grating, which can break the characteristics of the one-dimensional grating; the second grating 311 maintains the diffraction order of the two-dimensional grating on both sides of the two-dimensional grating (the grating structure of the first grating 301), while enabling the light transmitted to the second grating 311 to have light intensities of different diffraction orders. The second grating 311 is arranged in the transition grating zone 32 of the decoupling zone 3, so that the light energy of the decoupling zone 3 can be reasonably utilized.
[0076] Therefore, in the embodiment of the present application, a transition grating area 32 is introduced into the out-coupling area 3, wherein the second grating 311 in the transition grating area 32 is rotated by a preset angle relative to the first grating 301, and the light intensity of at least one side of the diffraction order of the light transmitted to the transition grating area 32 is adjusted without reducing the diffraction order of the first grating 301, so that the light energy in the out-coupling area 3 can be reasonably distributed, and the final imaging picture quality is good and the optical efficiency is high.
[0077] In an optional embodiment, the coupling-in region 2 and the coupling-out region 3 may be located on the same surface of the light-guiding substrate 1 , or may be located on two opposite surfaces of the light-guiding substrate 1 .
[0078] The diffraction grating in the coupling-in region 2 and the diffraction grating in the coupling-out region 3 can form a closed grating vector polygon. The coupling-in region 2 can be composed of a single one-dimensional or two-dimensional grating or a plurality of one-dimensional or two-dimensional gratings. The coupling-out region 3 can be composed of a single two-dimensional grating or a plurality of one-dimensional or two-dimensional gratings.
[0079] The direction of the one-dimensional grating vector is perpendicular to its grating line, which is the direction of its periodic change, and its length is equal to the reciprocal of the grating period. The two-dimensional grating is periodically distributed in both horizontal and vertical directions.
[0080] In one embodiment, referring to Figure 4 and Figure 5 The first grating 301 includes a plurality of first grating units 3011, the second grating 311 includes a plurality of second grating units 3111, and the first grating units 3011 and the second grating units 3111 have the same shape;
[0081] In the second grating unit 3111 and the first grating unit 3011 corresponding to each other, the second grating unit 3111 is rotated by a preset angle on the surface of the light guide substrate 1 relative to the first grating unit 3011 .
[0082] In this embodiment, the first grating 301 is disposed in the two-dimensional grating region 30 , the first grating 301 is a two-dimensional grating, and the first grating 301 includes a plurality of first grating units 3011 . The first grating unit 3011 is a basic unit of the first grating 301 .
[0083] The second grating 311 includes a plurality of second grating units 3111, and the second grating units 3111 are basic units of the first grating 301. The second grating units 3111 are between a one-dimensional grating and a two-dimensional grating.
[0084] The second grating 311 rotates by a preset angle relative to the first grating 301 on the surface of the light guide substrate 1, which is achieved by rotating the first grating units 3011 in the first grating 301. For example, each second grating unit 3111 rotates by a preset angle relative to each first grating unit 3011 on the surface of the light guide substrate 1. In this way, when each second grating unit 3111 modulates the light, the light diffracted in different directions has different light intensities, and finally the purpose of reasonably utilizing the light energy of the outcoupling region 3 is achieved.
[0085] In one embodiment, referring to Figure 4 and Figure 5 The second grating 311 is rotated at a preset angle relative to the first grating 301 on the surface of the light guide substrate 1 to weaken the intensity of the diffraction order of the light propagating to the position of the second grating 311 away from the two-dimensional grating area 30.
[0086] Specifically, the second grating 311 in the transition region is relatively close to the middle of the outcoupling region 3, the second grating 311 is rotated by a first preset angle relative to the first grating 301, the second grating 311 is arranged at a position gradually approaching the middle of the outcoupling region 3, and the light intensity after the light transmitted to the second grating 311 is modulated is weaker than the light intensity after the light transmitted to the first grating 301 is modulated;
[0087] As the second grating 311 in the transition region gradually moves away from the middle of the outcoupling region 3, the second grating 311 rotates relative to the first grating 301 by a second preset angle, and the modulated light intensity of the light transmitted to the second grating 311 is weaker than the modulated light intensity of the light transmitted to the first grating 301.
[0088] In this way, in the outcoupling area 3, the light energy can be more reasonably distributed after pupil expansion, which can improve the optical efficiency of the entire light guide device.
[0089] In one embodiment, referring to Figure 5 , the first grating 301 modulates the first light 01 propagating thereto into a second light 02 and a third light 03, the second light 02 is transmitted close to the two-dimensional grating area 30, and the third light 03 is transmitted away from the two-dimensional grating area 30;
[0090] The light intensity of the second light 02 is equal to the light intensity of the third light 03 .
[0091] Specifically, the outcoupling area 3 has a relatively strong symmetry with respect to the FOV. The first grating 301 is located in the two-dimensional grating area 30, and the two-dimensional grating area 30 is located in the middle of the outcoupling area 3. Therefore, after the first grating 301 modulates the first light 01 propagating thereto, diffracted light rays in different directions are formed after modulation, specifically, the second light 02 and the third light 03 are formed after modulation. The light intensity of the diffracted light rays in different directions has a relatively strong symmetry. When the light intensity of the second light 02 is equal to the light intensity of the third light 03, the image quality emitted by the light guide device is better.
[0092] In one embodiment, referring to Figure 3-Figure 4 The second grating 311 modulates the first light propagating thereto into a second light 02 and a third light 03, wherein the second light 02 is transmitted close to the two-dimensional grating area 30, and the third light 03 is transmitted away from the two-dimensional grating area 30;
[0093] The light intensity of the third light 03 is less than the light intensity of the second light 02 .
[0094] Specifically, the second grating 311 is located in the transition grating area 32, the transition grating area 32 is located on one side of the two-dimensional grating area 30, and the transition grating area 32 is arranged away from the middle of the outcoupling area 3. Therefore, when the second grating 311 modulates the light, the modulated light has different light intensities in different diffraction directions (different diffracted light has different light diffraction efficiencies, for example, weak light intensity and low light diffraction efficiency), so that the light intensity can be reasonably transitioned, and finally the purpose of reasonably utilizing the light energy is achieved.
[0095] For example, the second grating 311 modulates the light propagating thereto into the second light 02 and the third light 03, and the light intensity of the third light 03 is weaker than the light intensity of the second light 02, so that in the outcoupling zone 3, the light intensity can reasonably transition from the middle of the outcoupling zone 3 to the middle of the outcoupling zone 3, thereby ultimately achieving the purpose of reasonably utilizing light energy.
[0096] Specifically, the second grating 311 has the same diffraction order as the first grating 301, but has different light intensities for light in different diffraction directions; the second grating 311 has different diffraction orders relative to the one-dimensional grating set in the one-dimensional grating area 31, specifically, the diffraction order is increased. Figure 6 The one-dimensional grating in the one-dimensional grating area 31 only has the diffraction order of the second light ray 02 for the first light ray 01 propagating thereto, but does not have the diffraction order of the third light ray 03.
[0097] In one embodiment, the first grating 301 is a symmetrical structure.
[0098] Specifically, the first grating 301 is a symmetrical structure, for example, a central symmetrical structure or an axisymmetric structure. Specifically, the two-dimensional grating region 30 is located in the middle of the outcoupling region 3, and the grating structure of the two-dimensional grating region 30 makes the diffraction order light intensity of the pupil expansion on both sides similar, and the second grating 311 has its own symmetry.
[0099] In one embodiment, the preset angle is 30° to 85°, and preferably, the preset angle is 55° to 75°.
[0100] This embodiment limits the rotation angle of the second grating 311 relative to the first grating 301 . For example, the rotation angle of the second grating 311 relative to the first grating 301 is smaller. The second grating 311 is arranged in the transition grating area 32 . The second grating 311 is arranged relatively close to the two-dimensional grating area 30 .
[0101] For example, the second grating 311 rotates at a larger angle relative to the first grating 301, and the second grating 311 is disposed in the transition grating region 32, and the second grating 311 is disposed relatively far away from the two-dimensional grating. For example, in the transition grating region 32, the further away the second grating 311 is from the two-dimensional grating region 30, the second grating 311 modulates the light propagating thereto, so that the light intensity of the diffracted light diffracted away from the two-dimensional grating region 30 gradually weakens.
[0102] In one embodiment, referring to Figure 2 and Figure 6 The outcoupling region 3 also includes a one-dimensional grating region 31 , which includes at least two and is located on opposite sides of the two-dimensional grating region 30 , and the transition grating region 32 is located between the two-dimensional grating region 30 and the one-dimensional grating region 31 .
[0103] In this embodiment, the decoupling area 3 is designed as a partition. The decoupling area 3 includes a two-dimensional grating area 30, a transition grating area 32 and a one-dimensional grating area 31. In the direction from the middle of the decoupling area 3 to the middle of the decoupling area 3, the grating structure of the decoupling area 3 has the characteristic of changing from a one-dimensional grating to a two-dimensional grating. In this way, according to the position of the light in the decoupling area 3, the light has different light intensities, and finally achieves the purpose of rationally utilizing the light energy. For example, referring to Figure 2 The one-dimensional grating region 31 is arranged near the edge of the outcoupling region 3 , and the grating structure of the one-dimensional grating region 31 only realizes the diffraction order in one direction (the diffraction direction toward the middle of the outcoupling region 3 ).
[0104] Reference Figure 2-Figure 4 The transition grating region 32 is far away from the edge position of the out-coupling region 3. Compared with the grating structure of the one-dimensional grating region 31, the diffraction order light of the grating structure of the transition grating region 32 in another direction (the diffraction direction away from the middle of the out-coupling region 3) needs to be strengthened.
[0105] Reference Figure 2 and Figure 5 The two-dimensional grating region 30 is located in the middle of the outcoupling region 3. The grating structure of the two-dimensional grating region 30 makes the diffraction order light intensities of the pupil expansions on both sides similar.
[0106] For example, in the transition grating region 32, the farther the second grating 311 is from the two-dimensional grating region 30, the second grating 311 modulates the light propagating to it, so that the light intensity of the diffracted light diffracted away from the two-dimensional grating region 30 gradually weakens, until the grating structure reaches the one-dimensional grating region 31 and does not diffract the diffracted light away from the two-dimensional grating region 30.
[0107] In this way, in the outcoupling area 3, the light energy can be more reasonably distributed after pupil expansion, which can improve the optical efficiency of the entire light guide device.
[0108] In one embodiment, referring to Figure 6 The one-dimensional grating region 31 includes a plurality of third grating units 3211, and the third grating units 3211 are long strip gratings.
[0109] Specifically, the long strip grating has the characteristics of a one-dimensional grating. After the light propagating to it is modulated, it only diffracts the diffracted light transmitted toward the two-dimensional grating area 30, so that in the outcoupling area 3, the light energy can be more reasonably distributed after pupil expansion, which can improve the optical efficiency of the entire light-guiding device.
[0110] In one embodiment, referring to Figure 2, the outcoupling region 3 further includes a one-dimensional grating region 31, the one-dimensional grating region 31 includes at least two and is located at opposite sides of the two-dimensional grating region 30, and the transition grating region 32 is located between the two-dimensional grating region 30 and the one-dimensional grating region 31;
[0111] The one-dimensional grating region 31 includes a plurality of third grating units 3211 , and the third grating units 3211 are long strip gratings.
[0112] Specifically, the outcoupling zone 3 needs to have both pupil expansion and outcoupling functions. The outcoupling zone 3 includes different types of gratings arranged in zones, and introduces a transition grating zone 32 between the two-dimensional grating zone 30 and the one-dimensional grating zone 31, whose diffraction behavior is between the two.
[0113] Referring to the figure, 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 to couple the light out at the outermost edge of the outcoupling area 3, and a second grating 311 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.
[0114] In one embodiment, referring to Figure 7-Figure 9 The first grating unit 3011 and the third grating unit 3211 have the same width, and in the vector direction of the third grating unit 3211, the grating lines of the first grating unit 3011 are parallel.
[0115] Specifically, refer to Figure 7 , the third grating unit 3211 is a long strip grating. The shape of the first grating unit 3011 can be determined by a first angle between the first reference line 41 and the side of the long strip grating extending along the length direction, and a second angle between the second reference line 42 and the side of the long strip grating extending along the length direction. The first reference line 41 and the second reference line 42 can be parallel to or form an angle with the vector direction of the third grating unit 3211.
[0116] Reference Figure 5 When the first angle a1 and the second angle a2 are both 90°, the first grating unit 3011 is rectangular.
[0117] Reference Figure 8 When the first angle a1 and the second angle a2 are equal but not equal to 90°, the first grating unit 3011 is a parallelogram.
[0118] Reference Fig. 9 When the first angle a1 and the second angle a2 are not equal, the first grating unit 3011 is an irregular trapezoid.
[0119] It should be noted that, in this embodiment, the first grating unit 3011 is listed as a rectangle, a parallelogram and an irregular trapezoid, but the shape of the first grating unit 3011 includes but is not limited to a rectangle, a parallelogram and an irregular trapezoid. The shape of the first grating unit 3011 is related to the third grating unit 3211, and the length of the grating line of the third grating unit 3211 and the inclination direction of the grating line can be adjusted according to the structure of the third grating unit 3211 to obtain the first grating unit 3011.
[0120] In one embodiment, referring to Fig.10 , the outcoupling region 3 is provided on a surface of the light guide substrate 1;
[0121] In the outcoupling region 3, two opposite sides of the grating structure 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. Fig.10 The two opposite sides of the grating structure and the surface of the light guide substrate 1 form an angle B1 and an angle B2 respectively, and the angle range of the angle B1 and the angle B2 is: 20° to 160°.
[0122] When the grating structure is a step grating, the first grating 301 may not be a symmetrical structure. For example, the first grating 301 is a step grating, and a certain grating line of the step grating is used as the rotation axis, and the step grating is rotated on the surface of the light-guiding substrate 1, and the second grating 311 is formed by rotating at a preset angle. The second grating 311 modulates the light transmitted thereto into double-sided diffraction, wherein the light intensity of the diffraction order away from the two-dimensional grating area 30 is weakened, so the second grating 311 modulates the light transmitted thereto into two diffracted light rays, and the optical intensities of the two diffracted light rays are different, and a gradual transition of light energy is formed in the outcoupling area 3, which can improve the diffraction efficiency of the outcoupling area 3, thereby improving the imaging quality.
[0123] In a second aspect, an optical module is provided. The optical module comprises:
[0124] A light guide device as described above; and an optical machine, wherein the optical machine is used to project light or an image into the light guide device.
[0125] Among them, the light guiding device is applied to the optical module, and the light energy in the entire outcoupling area 3 can be distributed more flexibly and reasonably from the middle to the edge, forming a gradual transition of light energy in the outcoupling area 3, which can improve the diffraction efficiency of the outcoupling area 3, thereby improving the imaging quality.
[0126] In a third aspect, a head mounted display device is provided, wherein the head mounted display device comprises: a housing; and the optical module as described in the second aspect.
[0127] 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 limitations on this.
[0128] The specific implementation of the optical module and the head-mounted display device of the embodiments of the present application can refer to the above-mentioned embodiments of the light guide device, 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.
[0129] 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.
[0130] 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 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 a two-dimensional grating region (30) and a transition grating region (32); The two-dimensional grating region (30) is located in the middle of the outcoupling region (3), and the transition grating regions (32) are provided in at least two portions and are disposed on opposite sides of the two-dimensional grating region (30); The two-dimensional grating region (30) comprises a first grating (301), and the transition grating region (32) comprises a second grating (311), the first grating (301) and the second grating (311) are both capable of realizing double-sided diffraction of light propagating thereto, and the second grating (311) is rotated by a preset angle on the surface of the light-guiding substrate (1) relative to the first grating (301) to adjust the light intensity of at least one diffraction order of the light propagating to the position of the second grating (311).
2. The light guide device according to claim 1, characterized in that: The first grating (301) includes a plurality of first grating units (3011), the second grating (311) includes a plurality of second grating units (3111), and the first grating units (3011) and the second grating units (3111) have the same shape; In the second grating unit (3111) and the first grating unit (3011) corresponding to each other, the second grating unit (3111) is rotated by a preset angle on the surface of the light guide substrate (1) relative to the first grating unit (3011).
3. The light guide device according to claim 1, characterized in that: The second grating (311) is rotated at a preset angle relative to the first grating (301) on the surface of the light-guiding substrate (1) to weaken the intensity of the diffraction order of the light propagating to the position of the second grating (311) and away from the two-dimensional grating area (30).
4. The light guide device according to claim 1, characterized in that: The first grating (301) modulates the first light (01) propagating thereto into a second light (02) and a third light (03), wherein the first light (01) is transmitted close to the two-dimensional grating area (30), and the third light (03) is transmitted away from the two-dimensional grating area (30); The light intensity of the second light (02) is equal to the light intensity of the third light (03).
5. The light guide device according to claim 1, characterized in that: The second grating (311) modulates the first light (01) propagating thereto into a second light (02) and a third light (03), wherein the second light (02) is transmitted close to the two-dimensional grating area (30), and the third light (03) is transmitted away from the two-dimensional grating area (30); The light intensity of the third light (03) is smaller than the light intensity of the second light (02).
6. The light guide device according to claim 1, characterized in that: The first grating (301) is a symmetrical structure.
7. The light guide device according to claim 1, characterized in that: The preset angle is 30° to 85°.
8. The light guide device according to claim 1, characterized in that: The outcoupling region (3) further comprises a one-dimensional grating region (31), wherein the one-dimensional grating region (31) comprises at least two and is located at opposite sides of the two-dimensional grating region (30), and the transition grating region (32) is located between the two-dimensional grating region (30) and the one-dimensional grating region (31).
9. The light guide device according to claim 8, characterized in that: The one-dimensional grating region (31) comprises a plurality of third grating units (3211), and the third grating units (3211) are long strip gratings.
10. The light guide device according to claim 2, characterized in that: The outcoupling region (3) further comprises a one-dimensional grating region (31), the one-dimensional grating region (31) comprises at least two and is located at two opposite sides of the two-dimensional grating region (30), and the transition grating region (32) is located between the two-dimensional grating region (30) and the one-dimensional grating region (31); The one-dimensional grating region (31) comprises a plurality of third grating units (3211), and the third grating units (3211) are long strip gratings.
11. The light guide device according to claim 10, characterized in that: The first grating unit (3011) and the third grating unit (3211) have the same width, and in the vector direction of the third grating unit (3211), the grating lines of the first grating unit (3011) are parallel.
12. 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 form angles with the surface of the light-guiding substrate (1), and the angles are 20° to 160°; or, the grating structure is a step grating.
13. An optical module, characterized in that: The optical module comprises: The light guide device according to any one of claims 1 to 12; and An optical machine is used to project light or an image into the light guiding device.
14. A head mounted display device, characterized in that: The head mounted display device comprises: A housing; and an optical module as claimed in claim 13.