Grating structure, light guide device and head-mounted display device

Abstract

Provided in the embodiments of the present application are a grating structure, a light guide device and a head-mounted display device. The grating structure comprises a plurality of grating units periodically arranged at intervals, and a filling material filled between adjacent grating units and covering top surfaces of the plurality of grating units, wherein each grating unit has a first refractive index n1, the filling material has a second refractive index n2, and the grating structure satisfies: the absolute value of the difference between n1 and n2 is less than or equal to 0.5. With regard to the grating structure provided in the embodiments of the present application, the grating structure is newly designed, such that the diffraction efficiency of a diffraction behavior can be reduced, thereby preventing rainbow patterns from being formed in human eyes.

Description

Grating structure, light guide device and head-mounted display device

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 13, 2023, with application number 202311508079.4 and invention name “Grating structure, 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 grating structure, a light-guiding device, and a head-mounted display device. Background Art

[0003] Augmented reality (AR) is a technology that combines virtual information with the real world. Diffractive waveguides are currently considered the best optical display solution for AR.

[0004] However, during use, diffraction waveguides often diffract strong light sources from above the user's head, typically indoor lighting, into the eye. Furthermore, the dispersion characteristics of the grating create rainbow patterns in the eye. Current solutions typically employ a holographic lens, Hololens, and paint the upper surface of the optical device black to block out ambient light from above. However, this approach results in a limited field of view.

[0005] Summary of the Invention

[0006] The purpose of this application is to provide a new technical solution for a grating structure, a light-guiding device, and a head-mounted display device.

[0007] In a first aspect, the present application provides a grating structure. The grating structure includes a plurality of grating units arranged at periodic intervals and a filling material filled between adjacent grating units, wherein the filling material covers the top surfaces of the plurality of grating units;

[0008] The grating unit has a first refractive index n1, the filling material has a second refractive index n2, and the grating structure satisfies: the absolute value of the difference between n1 and n2 is ≤0.5.

[0009] Optionally, the grating structure satisfies: 0.1≤abs(n1-n2)<0.5.

[0010] Optionally, the grating structure satisfies: 0.2≤abs(n1-n2)≤0.3.

[0011] Optionally, the filling material is higher than a target height H of top surfaces of the plurality of grating units, and the target height H satisfies: H≤150 nm.

[0012] Optionally, the filling material is filled between adjacent grating units, and the filling method includes any one of atomic layer deposition ALD, spray coating, spin coating, physical vapor deposition PVD, chemical vapor deposition CVD, and plasma enhanced chemical vapor deposition PECVD.

[0013] Optionally, the grating structure is an in-coupling grating or an out-coupling grating, and a coating is provided on the grating structure.

[0014] Optionally, the filling material is glue, and the material of the grating unit is silicon oxide, titanium oxide, aluminum oxide or embossed glue.

[0015] Optionally, the grating structure is a one-dimensional grating or a two-dimensional grating, and the grating unit includes a tilted grating unit, a stepped grating unit or a rectangular grating unit.

[0016] In a second aspect, embodiments of the present application provide a light guide device comprising: a substrate, and an incoupling region and an outcoupling region disposed on the substrate; wherein the incoupling region and / or the outcoupling region comprises the grating structure described in the first aspect.

[0017] The present application provides a head-mounted display device. The head-mounted display device includes:

[0018] a housing; and

[0019] The light guiding device as described in the second aspect.

[0020] The beneficial effects of this application are:

[0021] The grating structure provided in the embodiments of the present application can be applied to diffraction optical waveguide solutions. By redesigning the grating structure, specifically by filling the air gaps between adjacent grating units with a filling material having a certain refractive index, and controlling the refractive index difference between the grating units and the filling material to be 0.5 or less, this design can reduce the diffraction efficiency of the diffraction behavior and avoid the formation of undesirable phenomena such as rainbow patterns in the human eye. At the same time, it will not affect the field of view of the human eye, greatly improving the user's visual experience.

[0022] 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

[0023] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0024] FIG1 is a schematic diagram of a grating structure according to an embodiment of the present application;

[0025] FIG2 is a second schematic diagram of a grating structure provided in an embodiment of the present application;

[0026] FIG3 is a light path diagram of a conventional light guide device;

[0027] FIG4 is a simulation diagram of the diffraction behavior of a traditional one-dimensional grating;

[0028] FIG5 is a schematic diagram of the structure of a conventional grating;

[0029] FIG6 is a graph showing the diffraction efficiency of a conventional grating at different incident angles;

[0030] FIG7 is a second graph showing the diffraction efficiency of a conventional grating at different incident angles;

[0031] FIG8 is a third graph showing the diffraction efficiency of a conventional grating at different incident angles;

[0032] FIG9 is a graph showing the diffraction efficiency of a grating structure at different incident angles according to an embodiment of the present application;

[0033] FIG10 is a second graph showing the diffraction efficiency of a grating structure at different incident angles according to an embodiment of the present application;

[0034] FIG11 is a third graph showing the diffraction efficiency of a grating structure at different incident angles according to an embodiment of the present application;

[0035] FIG12 is a graph showing the diffraction efficiency of a grating structure at different incident angles according to another embodiment of the present application;

[0036] FIG13 is a second graph showing diffraction efficiency of a grating structure at different incident angles according to another embodiment of the present application;

[0037] FIG14 is a third diagram of diffraction efficiency of a grating structure at different incident angles provided by another embodiment of the present application;

[0038] FIG15 is a graph showing the diffraction efficiency of a grating structure at different incident angles according to yet another embodiment of the present application;

[0039] FIG16 is a second graph showing diffraction efficiency of a grating structure at different incident angles according to another embodiment of the present application;

[0040] FIG17 is a third graph showing diffraction efficiency of a grating structure at different incident angles according to another embodiment of the present application;

[0041] FIG18 is a schematic structural diagram of a light guide device provided in an embodiment of the present application.

[0042] Explanation of reference numerals: 1. grating unit; 2. filling material; 3. air gap; 01. human eye; 02. light source; 03. light; 100. substrate; 101. coupling-in region; 102. coupling-out region. DETAILED DESCRIPTION

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] The grating structure, light guide device and head-mounted display device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0049] According to one aspect of an embodiment of the present application, a grating structure is provided. The grating structure is suitable for use in AR diffractive optical solutions, and can be applied, for example, to the outcoupling region 102 and / or the incoupling region 101 of a diffractive optical waveguide element, as shown in FIG18 . In particular, when applied to the outcoupling region 102, the grating structure can suppress rainbow fringes.

[0050] The grating structure provided in an embodiment of the present application, as shown in Figures 1 and 2, comprises a plurality of periodically spaced grating units 1 and a filling material 2 filling between adjacent grating units 1, with the filling material 2 covering the top surfaces of the plurality of grating units 1. The grating units 1 have a first refractive index n1, the filling material 2 has a second refractive index n2, and the grating structure satisfies the following requirement: the absolute value of the difference between n1 and n2 is ≤ 0.5.

[0051] The grating structure provided by the above embodiment can be applied to a diffraction optical waveguide element. The grating structure can be a one-dimensional grating or a two-dimensional grating.

[0052] Referring to FIG3 , when a human eye 01 is wearing a diffraction optical waveguide component, if there is a light source 02 above the user's head, such as an indoor lamp, and the light 03 emitted by the light source is, for example, external ambient light, and the outcoupling grating on the diffraction optical waveguide component is the traditional grating shown in FIG5 (with air gaps 3 between adjacent grating units 1), the diffraction behavior shown in FIG3 will occur: due to the diffraction characteristics of the grating itself, the traditional grating will diffract the light 03 emitted by the light source 02 (lamp) above the head into the human eye 01. At the same time, due to the dispersion characteristics of the grating, when the light 03 is diffracted by the grating into the human eye 01, it will form rainbow patterns in the human eye 01. This phenomenon will greatly affect the user's visual experience, and therefore needs to be avoided as much as possible.

[0053] Specifically, referring to FIG4 , taking the outcoupling grating on the diffraction optical waveguide element as a one-dimensional grating as an example, it can be determined from the simulation diagram shown in FIG4 that the diffraction behavior shown in FIG3 is: wherein light A is the light 03 emitted by the simulated light source 02 above the head, and the corresponding light marked as T-1 is the rainbow pattern diffracted into the human eye 01.

[0054] Refer to Figure 5, which shows the structure of a traditional grating. Adjacent grating elements 1 are separated by air gaps 3. Under standard conditions, the refractive index of air for visible light is approximately 1.0. This means that traditional gratings can only modify the refractive index difference between the grating elements 1 and the air gaps 3 by selecting the material of the grating elements 1. This results in a limited number of variable parameters and a very limited ability to modulate diffraction behavior.

[0055] In the grating structure provided in an embodiment of the present application, as shown in Figures 1 and 2, a filling material 2 is filled between adjacent grating units 1, and the filling material 2 is used to replace air. In this case, the refractive index of the filling material 2 can be selected as appropriate as needed. This allows for better and more flexible control of the refractive index difference between the filling material 2 and the grating unit 1, so that the absolute value of the refractive index difference between the two is controlled to be less than or equal to 0.5, thereby suppressing the generation of rainbow patterns.

[0056] It should be noted that the first refractive index n1 of the grating element 1 may be greater than the second refractive index n2 of the filling material 2. Alternatively, the second refractive index n2 of the filling material 2 may be greater than the refractive index of the grating element 1. This application does not impose any restrictions on this, as long as the refractive index difference between the grating element 1 and the filling material 2 can be controlled to be less than or equal to 0.5. Based on this, it is only necessary to limit the absolute value of the refractive index difference between the grating element 1 and the filling material 2, that is, |(n1-n2)|, to be less than or equal to 0.5.

[0057] The grating structure provided in the embodiments of the present application can be applied to a diffraction optical waveguide solution. By redesigning the grating structure, namely, filling the air gaps 3 between adjacent grating units 1 with a filling material 2 having a certain refractive index, and controlling the refractive index difference between the grating units 1 and the filling material 2 to be 0.5 or less, this design can reduce the diffraction efficiency corresponding to the diffraction behavior to avoid the formation of undesirable phenomena such as rainbow patterns in the human eye 01. At the same time, it does not affect the field of view of the human eye 01, thereby greatly improving the user's visual experience.

[0058] According to the grating structure provided in the embodiment of the present application, the first refractive index n1 of the grating unit 1 is, for example, 1.9, and the second refractive index n2 of the filling material 2 is, for example, in the range of 1.4 to 1.8. Within the aforementioned refractive index range, a wide range of materials are available for the grating unit 1 and the filling material 2, without increasing the difficulty of material selection during processing or the production cost.

[0059] The filling material 2 can be glue with different refractive indices.

[0060] In one example, the first refractive index n1 of the grating unit 1 is 1.9, the second refractive index n2 of the filling material 2 is 1.4, and the difference between the refractive indices thereof is 0.5.

[0061] In one example, the first refractive index n1 of the grating unit 1 is 1.9, the second refractive index n2 of the filling material 2 is 1.8, and the difference between the refractive indices thereof is 0.1.

[0062] In one example, the first refractive index n1 of the grating unit 1 is 1.9, the second refractive index n2 of the filling material 2 is 1.7, and the difference between the refractive indices thereof is 0.2.

[0063] In one example, the first refractive index n1 of the grating unit 1 is 1.9, the second refractive index n2 of the filling material 2 is 1.6, and the difference between the refractive indices thereof is 0.3.

[0064] In some examples of the present application, the grating structure satisfies: 0.1≤abs(n1-n2)<0.5.

[0065] Referring to the conventional grating shown in FIG5 , the first refractive index n1 of the grating unit 1 is set to 1.9, and there is an air gap 3 between adjacent grating units 1. This is equivalent to the space between adjacent grating units 1 being air, and the refractive index of air is approximately 1. In this case, the refractive index difference between the grating unit 1 and the air gap 3 is 0.9, which is relatively large (greater than the 0.5 in this application). On this basis, referring to FIG6 to FIG8 , the diffraction order efficiencies corresponding to light of different wavelengths (simulating light 03 emitted by a light source 02 above the user's head (e.g., an indoor lamp), also referred to as ambient light) diffracted by a conventional grating into the human eye 01 at different incident angles are respectively shown.

[0066] It should be noted that the diffraction efficiency curves shown in FIG6 to FIG8 are the diffraction efficiency simulation results of light incident on the grating structure at a set angle and then diffracted by the grating structure into the human eye.

[0067] Specifically, Figure 6 shows the efficiency performance of each diffraction order when the light with a wavelength of 625nm is diffracted into the human eye 01 at an incident angle of 0° to 80° through the traditional grating shown in Figure 5; Figure 7 shows the efficiency performance of each diffraction order when the light with a wavelength of 525nm is diffracted into the human eye 01 at an incident angle of 0° to 80° through the traditional grating shown in Figure 5; Figure 8 shows the efficiency performance of each diffraction order when the light with a wavelength of 460nm is diffracted into the human eye 01 at an incident angle of 0° to 80°; in Figures 6 to 8: -1T represents the diffraction efficiency curve corresponding to the rainbow pattern. Within the incident angle range of 55° to 80° corresponding to the light 03 on the upper side of the user's head, the diffraction efficiency of the traditional grating is 3% to 7%, and the human eye 01 can see the rainbow pattern.

[0068] According to the optimized design of the grating structure in the above-described example of this application, referring to Figures 1 and 2 , the first refractive index n1 of the grating elements 1 is 1.9, and a filler material 2 is placed between adjacent grating elements 1, with a second refractive index n2 of 1.8. In this case, the refractive index difference between the grating elements 1 and the filler material 2 is 0.1. Furthermore, referring to Figures 9 to 11 , the diffraction order efficiencies corresponding to light of different wavelengths diffracted through the grating structure into the human eye O1 at different incident angles are shown.

[0069] Specifically, Figure 9 shows the diffraction efficiency of each diffraction order when a 625nm wavelength light is diffracted into the human eye 01 by the grating structure of the embodiment of the present application at an incident angle of 0° to 80°. Figure 10 shows the diffraction efficiency of each diffraction order when a 525nm wavelength light is diffracted into the human eye 01 by the grating structure of the embodiment of the present application at an incident angle of 0° to 80°. Figure 11 shows the diffraction efficiency of each diffraction order when a 460nm wavelength light is diffracted into the human eye 01 by the grating structure of the embodiment of the present application at an incident angle of 0° to 80°. In Figures 9 and 11, the diffraction efficiency curve corresponding to the rainbow pattern is represented by -1T. It can be seen that within the incident angle range of 55° to 80°, corresponding to the light ray 03 above the user's head, the corresponding -1T diffraction efficiency drops to <0.1%. At this point, the rainbow pattern is almost invisible to the human eye 01. However, when the refractive index difference between the grating unit 1 and the filling material 2 is 0.1, in order to achieve the above-mentioned diffraction efficiency, the height requirement of the grating unit 1 is relatively high, generally greater than 300 nm, and the process requirement is relatively high.

[0070] It should be noted that the diffraction efficiency curves shown in FIG9 to FIG11 are the diffraction efficiency simulation results of light incident on the grating structure at a set angle and then diffracted by the grating structure into the human eye.

[0071] According to the optimization of the grating structure described in the above example of this application, referring to Figures 1 and 2 , the first refractive index n1 of the grating elements 1 is 1.9, and a filler material 2 is placed between adjacent grating elements 1. The second refractive index n2 of the filler material 2 is 1.4. In this case, the refractive index difference between the grating elements 1 and the filler material 2 is 0.5. Furthermore, referring to Figures 12 to 14 , the diffraction order efficiencies corresponding to light of different wavelengths diffracted through the grating structure into the human eye O1 at different incident angles are shown.

[0072] Specifically, Figure 12 shows the diffraction efficiency of each diffraction order when a 625nm wavelength light is diffracted into the human eye 01 by the grating structure of the embodiment of the present application at an incident angle of 0° to 80°. Figure 13 shows the diffraction efficiency of each diffraction order when a 525nm wavelength light is diffracted into the human eye 01 by the grating structure of the embodiment of the present application at an incident angle of 0° to 80°. Figure 14 shows the diffraction efficiency of each diffraction order when a 460nm wavelength light is diffracted into the human eye 01 by the grating structure of the embodiment of the present application at an incident angle of 0° to 80°. In Figures 12 and 14, the diffraction efficiency curve corresponding to the rainbow pattern is represented by -1T. It can be seen that within the incident angle range of 55° to 80°, corresponding to the light 03 above the user's head, the corresponding -1T diffraction efficiency drops to 0.1% to 0.3%. Under this design, the human eye 01 is basically unable to see the rainbow pattern.

[0073] It should be noted that the diffraction efficiency curves shown in FIG. 12 to FIG. 14 are simulation results of the diffraction efficiency of light entering the grating structure at a set angle and then being diffracted by the grating structure into the human eye.

[0074] In some examples of the present application, the grating structure satisfies: 0.2≤abs(n1-n2)≤0.3.

[0075] According to the constraints satisfied by the grating structure shown in the above example, it is a more preferred solution of the present application.

[0076] Referring to Figures 1 and 2 , the first refractive index n1 of the grating elements 1 is 1.9, and a filler material 2 is placed between adjacent grating elements 1. The second refractive index n2 of the filler material 2 is 1.7. In this case, the refractive index difference between the grating elements 1 and the filler material 2 is 0.2. Furthermore, referring to Figures 15 to 17 , the diffraction order efficiencies corresponding to light of different wavelengths diffracted through the grating structure and entering the human eye O1 at different incident angles are shown.

[0077] Specifically, Figure 15 shows the efficiency performance of each diffraction order when a light ray with a wavelength of 625nm is diffracted into the human eye 01 through the grating structure of the embodiment of the present application at an incident angle of 0° to 80°; Figure 16 shows the efficiency performance of each diffraction order when a light ray with a wavelength of 525nm is diffracted into the human eye 01 through the grating structure of the embodiment of the present application at an incident angle of 0° to 80°; Figure 17 shows the efficiency performance of each diffraction order when a light ray with a wavelength of 460nm is diffracted into the human eye 01 through the grating structure of the embodiment of the present application at an incident angle of 0° to 80°; in Figures 15 to 17, the diffraction efficiency curve corresponding to the rainbow pattern is represented by -1T. It can be seen that within the incident angle range of 55° to 80° corresponding to the light ray 03 on the upper side of the user's head, the corresponding -1T diffraction efficiency is reduced to <0.1%.

[0078] According to the grating structure provided in the embodiments of the present application, by adjusting the refractive index difference between the filler material 2 between adjacent grating units 1 and the grating units 1, for example, to between 0.2 and 0.3 (inclusive), the corresponding -1T diffraction efficiency can be reduced to approximately 0.1% or below within the overhead incident angle range of 55° to 80°. Typically, indoor light is generally between 200 nits and 500 nits. After diffracting through the grating structure and entering the human eye 01, the rainbow ripple brightness is less than 0.5 nits. At this brightness, the human eye 01 is essentially imperceptible, effectively suppressing the rainbow ripple.

[0079] It should be noted that the diffraction efficiency curves shown in FIG. 15 to FIG. 17 are simulation results of the diffraction efficiency of light incident on the grating structure at a set angle and then diffracted by the grating structure into the human eye.

[0080] 12 to 14 , when the absolute value of the refractive index difference between the grating unit 1 and the filling material 2 is 0.5, according to the simulation results, the diffraction efficiency corresponding to the grating structure can be reduced to 0.1% to 0.3%. At this time, the brightness of the rainbow pattern formed after the light is diffracted by the diffraction structure into the human eye 01 is relatively small, for example, less than 0.5 nits. The brightness is basically imperceptible to the human eye 01, and the rainbow pattern is fully suppressed.

[0081] Referring to Figures 9 to 11, and Figures 15 to 17, when the absolute value of the refractive index difference between the grating unit 1 and the filling material 2 is 0.1 or 0.2, the diffraction efficiency corresponding to the grating structure can be reduced to 0.1% to 0.3%, and the corresponding brightness is not noticeable to the human eye 01, thereby fully suppressing the rainbow stripes. In other words, within the design range of the refractive index difference of 0.1 to 0.5 (excluding the end value of 0.5), the smaller the refractive index difference between the grating unit 1 and the filling material 2, the better the effect of suppressing the rainbow stripes. However, it should be noted that when the refractive index difference between the grating unit 1 and the filling material 2 is only 0.1, the corresponding grating height requirement is relatively high, generally greater than 300nm, and the process requirements are relatively high.

[0082] The external ambient light is, for example, light 03 emitted by an indoor lamp, see FIG. 3 .

[0083] In some examples of the present application, referring to FIG. 2 , the filling material 2 is higher than a target height H of the top surfaces of the plurality of grating units, and the target height H satisfies: H≤150 nm.

[0084] According to the grating structure provided in the embodiments of the present application, when filling material 2 is filled between adjacent grating elements 1, in order for the filling material 2 to completely fill the air spaces 3 between the adjacent grating elements 1, it is necessary to cover the top surfaces of the plurality of grating elements 1 on one side and overflow the top surfaces by a certain height. Generally speaking, the smaller the height to which the filling material 2 overflows the top surfaces of the plurality of grating elements 1, the better the rainbow pattern suppression effect.

[0085] In addition, the height of the filling material 2 overflowing from the top surface of the grating unit 1 is also affected by the process.

[0086] According to the above example, the overflow height of the filling material 2 is controlled to 150nm or less. This thickness has a good effect on suppressing rainbow patterns, and it is not difficult to control this thickness using existing filling methods, such as atomic layer deposition ALD and physical vapor deposition PVD.

[0087] In some examples of the present application, the filling material 2 is filled between adjacent grating units 1, and the filling method includes any one of atomic layer deposition ALD, spray coating, spin coating, physical vapor deposition PVD, chemical vapor deposition CVD, and plasma enhanced chemical vapor deposition PECVD.

[0088] In some examples of the present application, the grating structure is an in-coupling grating or an out-coupling grating, and a coating is provided on the grating structure.

[0089] A coating is deposited on the surface of the grating structure, and the coating can be used to improve the diffraction efficiency of the grating structure.

[0090] For example, the grating structure is an in-coupling grating, and the coating on the in-coupling grating may be made of a metal oxide material.

[0091] For example, the grating structure is an outcoupling grating, and the coating on the outcoupling grating may be a non-metallic oxide material or a non-metallic material.

[0092] In some examples of the present application, the filling material 2 is glue, and the material of the grating unit 1 is silicon oxide, titanium oxide, aluminum oxide or embossed glue.

[0093] Specifically, the filling material 2 may be, for example, glue with a set refractive index, such as glue with a refractive index of 1.4 to 1.8.

[0094] In some examples of the present application, the grating structure is a one-dimensional grating or a two-dimensional grating, and the grating unit includes a tilted grating unit, a stepped grating unit or a rectangular grating unit.

[0095] The grating structure provided in the embodiments of the present application can be applied to the diffraction optical waveguide element (lens) in the head-mounted display device, which includes an AR display device and can also be used in MR display or XR display.

[0096] According to another aspect of the present application, an embodiment of the present application further provides a light-guiding device, see Figure 18, the light-guiding device includes a substrate 100, and a coupling-in region 101 and a coupling-out region 102 arranged on the substrate 100; the coupling-in region 101 and / or the coupling-out region 102 include the grating structure as described above.

[0097] The light guide device is, for example, a diffraction light waveguide element, and the substrate 100 is a waveguide substrate.

[0098] The coupling-in region 101 is used to couple external light into the substrate 100 .

[0099] The outcoupling region 102 is a pupil expansion and outcoupling grating, which expands the coupled light from the coupling region 101 in both horizontal and vertical dimensions and couples the light out.

[0100] The coupling-in region 101 and the coupling-out region 102 may be placed on the upper surface or the lower surface of the substrate 100 in any arrangement or combination.

[0101] The grating structure provided in the embodiment of the present application is applied to the outcoupling region 102 of the light-guiding device, which can effectively suppress rainbow patterns.

[0102] For the entire light-guiding device, the coupling-in grating in the coupling-in region 101 and the coupling-out grating in the coupling-out region 102 form a closed grating vector polygon. The coupling-in region 101 can be composed of a single one-dimensional or two-dimensional grating or multiple one-dimensional or two-dimensional gratings. The coupling-out region 102 can be composed of a single two-dimensional grating or multiple one-dimensional or two-dimensional gratings.

[0103] According to the embodiment of the present application, the grating structure may be a one-dimensional grating or a two-dimensional grating.

[0104] The direction of the one-dimensional grating vector is perpendicular to the grating line and is the direction of its periodic change. Its length is equal to the inverse of the grating period.

[0105] The two-dimensional grating is periodically distributed in both the horizontal and vertical directions.

[0106] According to another aspect of the present application, an embodiment of the present application further provides a head-mounted display device, wherein the head-mounted display device includes a housing and the light guide device as described above.

[0107] The light guide component is, for example, a diffraction light waveguide element, which is disposed in the housing.

[0108] The head-mounted display device includes AR smart glasses or AR smart helmets, etc., which is not limited in the embodiments of the present application.

[0109] The specific implementation of the head-mounted display device of the embodiment of the present application can refer to the above-mentioned embodiments of the diffraction optical structure and the light-guiding device, and therefore at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0110] The above embodiments focus on the differences between the various embodiments. As long as the different optimization features of 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.

[0111] 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 grating structure, characterized in that: It comprises a plurality of grating units (1) arranged at periodic intervals and a filling material (2) filled between adjacent grating units (1), wherein the filling material (2) covers the top surfaces of the plurality of grating units (1); The grating unit (1) has a first refractive index n1, the filling material (2) has a second refractive index n2, and the grating structure satisfies: the absolute value of the difference between n1 and n2 is ≤0.

5.

2. The grating structure according to claim 1, characterized in that The grating structure satisfies: 0.1≤abs(n1-n2)<0.

5.

3. The grating structure according to claim 1, characterized in that The grating structure satisfies: 0.2≤abs(n1-n2)≤0.

3.

4. The grating structure according to any one of claims 1 to 3, characterized in that: The filling material (2) is higher than a target height H of the top surfaces of the plurality of grating units (1), and the target height H satisfies: H≤150nm.

5. The grating structure according to claim 4, characterized in that The filling material (2) is filled between adjacent grating units (1), and the filling method includes any one of atomic layer deposition ALD, spray coating, spin coating, physical vapor deposition PVD, chemical vapor deposition CVD and plasma enhanced chemical vapor deposition PECVD.

6. The grating structure according to claim 1, characterized in that The grating structure is an in-coupling grating or an out-coupling grating, and a coating is arranged on the grating structure.

7. The grating structure according to claim 1, characterized in that The filling material (2) is glue, and the material of the grating unit (1) is silicon oxide, titanium oxide, aluminum oxide or embossed glue.

8. The grating structure according to claim 1, characterized in that The grating structure is a one-dimensional grating or a two-dimensional grating, and the grating unit (1) comprises a tilted grating unit, a step grating unit or a rectangular grating unit.

9. A light guide device, characterized in that: It comprises a substrate (100), and a coupling-in region (101) and a coupling-out region (102) arranged on the substrate (100); The coupling-in region (101) and / or the coupling-out region (102) comprises a grating structure according to any one of claims 1 to 8.

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

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