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

Abstract

The embodiment of the invention provides a grating structure, a light guide device and head-mounted display equipment. Wherein the grating structure comprises a plurality of grating units and filling materials, the grating units are periodically arranged at intervals, the space between the adjacent grating units is filled with the filling materials, and the filling materials cover the top surfaces of the grating units; wherein the grating unit has a first refractive index n1, the filling material has a second refractive index n2, and the grating structure meets the condition that the absolute value of the difference between n1 and n2 is smaller than or equal to 0.5. According to the grating structure provided by the embodiment of the invention, the diffraction efficiency of the diffraction behavior can be reduced through the new design of the grating structure, and rainbow lines are prevented from being formed in human eyes.

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 grating structure, a light guide device and a head-mounted display device. Background Art

[0002] Augmented reality (AR) is a technology that combines virtual information with the real world. The diffraction waveguide solution is considered to be the best optical display solution in augmented reality technology.

[0003] However, during the user's use, the diffraction waveguide solution usually diffracts the strong light source from the upper side of the user's head, usually the indoor light, into the human eye due to the diffraction characteristics. At the same time, due to the dispersion characteristics of the grating, rainbow patterns will be formed in the human eye. The current solution is usually to use a holographic lens Hololens and blacken the upper side of the optical device to shield the ambient light from the upper side, but this method leads to the problem of limited field of view. Summary of the invention

[0004] 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.

[0005] In a first aspect, the present application provides a grating structure. The grating structure comprises 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;

[0006] 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.

[0007] Optionally, the grating structure satisfies: 0.1≤abs(n1-n2)<0.5.

[0008] Optionally, the grating structure satisfies: 0.2≤abs(n1-n2)≤0.3.

[0009] 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.

[0010] 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.

[0011] Optionally, the grating structure is an in-coupling grating or an out-coupling grating, and a coating is provided on the grating structure.

[0012] Optionally, the filling material is glue, and the material of the grating unit is silicon oxide, titanium oxide, aluminum oxide or embossed glue.

[0013] Optionally, the grating structure is a one-dimensional grating or a two-dimensional grating, and the grating unit includes a tilted grating unit, a step grating unit or a rectangular grating unit.

[0014] In a second aspect, an embodiment of the present application provides a light guide device, which includes: a substrate and an incoupling region and an outcoupling region disposed on the substrate; wherein the incoupling region and / or the outcoupling region includes the grating structure as described in the first aspect.

[0015] The present application provides a head mounted display device. The head mounted display device comprises:

[0016] a housing; and

[0017] A light guiding device as described in the second aspect.

[0018] The beneficial effects of this application are:

[0019] According to the grating structure provided in the embodiment of the present application, it can be applied to the diffraction optical waveguide solution. By redesigning the grating structure, specifically filling the air gap between adjacent grating units with a filling material with a certain refractive index, and controlling the refractive index difference between the grating unit and the filling material to be 0.5 or below 0.5, this design can reduce the diffraction efficiency of the diffraction behavior and avoid the formation of undesirable phenomena such as rainbow lines 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.

[0020] 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

[0021] 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.

[0022] Figure 1 One of the schematic diagrams of the grating structure provided in the embodiment of the present application;

[0023] Figure 2 A second schematic diagram of a grating structure provided in an embodiment of the present application;

[0024] Figure 3 This is the optical path diagram of a traditional light guide device;

[0025] Figure 4 This is a simulation diagram of the diffraction behavior of a traditional one-dimensional grating;

[0026] Figure 5 It is a schematic diagram of the structure of a traditional grating;

[0027] Figure 6 One of the diffraction efficiency curves of the traditional grating at different incident angles;

[0028] Figure 7 This is the second graph of diffraction efficiency of traditional grating at different incident angles;

[0029] Figure 8 The third graph is the diffraction efficiency curve of the traditional grating at different incident angles;

[0030] Fig. 9 One of the diffraction efficiency curves of the grating structure provided by one embodiment of the present application at different incident angles;

[0031] Fig.10 A second graph showing the diffraction efficiency of a grating structure at different incident angles provided by an embodiment of the present application;

[0032] Fig.11 A third graph showing the diffraction efficiency of a grating structure at different incident angles provided by an embodiment of the present application;

[0033] Fig.12 One of the diffraction efficiency curves of the grating structure at different incident angles provided by another embodiment of the present application;

[0034] Fig.13 A second graph of diffraction efficiency of a grating structure at different incident angles provided by another embodiment of the present application;

[0035] Fig.14 A third diagram of the diffraction efficiency of the grating structure at different incident angles provided by another embodiment of the present application;

[0036] Fig.15 One of the diffraction efficiency curves of the grating structure at different incident angles provided by yet another embodiment of the present application;

[0037] Fig.16 A second graph of diffraction efficiency of a grating structure at different incident angles provided by another embodiment of the present application;

[0038] Fig.17 A third graph of diffraction efficiency of a grating structure at different incident angles provided by another embodiment of the present application;

[0039] Fig.18A schematic diagram of the structure of a light guide device provided in an embodiment of the present application.

[0040] Description of reference numerals:

[0041] 1. Grating unit; 2. Filling material; 3. Air gap; 01. Human eye; 02. Light source; 03. Light; 100. Substrate; 101. Incoupling region; 102. Outcoupling region. DETAILED DESCRIPTION

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] The grating structure, light guide device and head-mounted display device provided in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0048] According to one aspect of an embodiment of the present application, a grating structure is provided. The grating structure is applicable to an AR diffractive optical solution, for example, it can be applied to the out-coupling region 102 and / or the in-coupling region 101 of a diffractive optical waveguide element. Fig.18 In particular, when applied to the outcoupling region 102, it can suppress rainbow patterns.

[0049] The grating structure provided in the embodiment of the present application is shown in FIG. Figure 1 and Figure 2The grating structure comprises a plurality of grating units 1 arranged at periodic intervals and a filling material 2 filled between adjacent grating units 1, and 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.

[0050] According to the grating structure provided in the above embodiment, it can be applied to a diffraction optical waveguide element. The grating structure can be a one-dimensional grating or a two-dimensional grating.

[0051] See also Figure 3 When the human eye 01 wears the diffractive optical waveguide element, if there is a light source 02 on the upper side of the user's head, such as an indoor lamp, the light 03 emitted by the light source is, for example, external ambient light, and the outcoupling grating on the diffractive optical waveguide element is Figure 5 The conventional grating shown in FIG. 1 (with air gaps 3 between adjacent grating elements 1) will Figure 3 Diffraction behavior shown in: Due to the diffraction characteristics of the grating itself, the traditional grating will diffract the light 03 emitted by the light source 02 (light) 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, rainbow patterns will be formed in the human eye 01. This phenomenon will greatly affect the user's visual experience, so it is necessary to avoid this situation as much as possible.

[0052] Specifically, see Figure 4 , taking the outcoupling grating on the diffraction optical waveguide element as a one-dimensional grating as an example, from Figure 4 The simulation diagram shown shows that Figure 3 The diffraction behavior shown in is: the 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.

[0053] See also Figure 5 , Figure 5 The structure of a conventional grating is shown in FIG. 1 , where an air gap 3 is formed between adjacent grating units 1. Under standard conditions, the refractive index of air for visible light is about 1.0. This means that conventional gratings can only change the refractive index difference between the grating unit 1 and the air gap 3 by selecting the material of the grating unit 1, with few variable parameters and very limited modulation capability for diffraction behavior.

[0054] The grating structure solution provided in the embodiment of the present application is shown in Figure 1 and Figure 2A filling material 2 is filled between adjacent grating units 1, and the filling material 2 is used to replace the air. At this time, the refractive index of the filling material 2 can be selected as a suitable material as needed, so that the refractive index difference between it and the grating unit 1 can be better and more flexibly controlled, 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 lines.

[0055] It should be noted that the first refractive index n1 of the grating unit 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 unit 1, and the present application does not impose any restrictions on this, as long as the refractive index difference between the grating unit 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 unit 1 and the filling material 2, that is, |(n1-n2)| to be less than or equal to 0.5.

[0056] According to the grating structure provided in the embodiment of the present application, it can be applied to the diffraction optical waveguide solution. By redesigning the grating structure, that is, filling the air gap 3 between the adjacent grating units 1 with a filling material 2 with a certain refractive index, and controlling the refractive index difference between the grating unit 1 and the filling material 2 to be 0.5 or less, the design can reduce the diffraction efficiency corresponding to the diffraction behavior to avoid the formation of rainbow patterns and other undesirable phenomena in the human eye 01, and at the same time will not affect the field of view of the human eye 01, thereby greatly improving the user's visual experience.

[0057] 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. The grating unit 1 and the filling material 2 can be made of a large number of materials within the above refractive index range, which will not increase the difficulty of material selection during processing, nor will it increase the production cost.

[0058] The filling material 2 can be glue with different refractive indices.

[0059] 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 of the two is 0.5.

[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 1.8, and the difference between the refractive indices of the two is 0.1.

[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 1.7, and the difference between the refractive indices of the two is 0.2.

[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 1.6, and the difference between the refractive indices of the two is 0.3.

[0063] In some examples of the present application, the grating structure satisfies: 0.1≤abs(n1-n2)<0.5.

[0064] See also Figure 5 In the conventional grating shown in FIG. 1 , the first refractive index n1 of the grating unit 1 is set to 1.9, and there is an air gap 3 between the adjacent grating units 1, which is equivalent to the air between the adjacent grating units 1, and the refractive index of the air is about 1. At this time, the refractive index difference between the grating unit 1 and the air gap 3 is 0.9, which is relatively large (greater than 0.5 in this application). On this basis, see Figures 6 to 8 , respectively showing the diffraction order efficiencies corresponding to light of different wavelengths (simulating light 03 emitted by a light source 02 above the user's head (such as an indoor lamp), which can also be called ambient light) diffracting into the human eye 01 through a traditional grating at different incident angles.

[0065] It should be noted that Figures 6 to 8 The diffraction efficiency curve shown is the simulation result of the diffraction efficiency of light entering the grating structure at a set angle and then diffracting through the grating structure into the human eye.

[0066] Specifically, Figure 6 The display shows the wavelength of 625nm light when the incident angle is 0°~80°. Figure 5 The conventional grating diffraction shown in the figure shows the efficiency performance of each diffraction order when it enters the human eye 01; Figure 7 The display shows the wavelength of 525nm light when the incident angle is 0°~80°. Figure 5 The conventional grating diffraction shown in the figure shows the efficiency performance of each diffraction order when it enters the human eye 01; Figure 8 The display shows the wavelength of 460nm light when the incident angle is 0°~80°. Figure 5 When the traditional grating diffraction shown enters the human eye 01, the corresponding efficiency performance of each diffraction order; Figures 6 to 8 Middle: -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.

[0067] According to the above example of the present application, the grating structure is optimized and designed, see Figure 1 and Figure 2 , the first refractive index n1 of the grating unit 1 is 1.9, a filling material 2 is filled between adjacent grating units 1, and the second refractive index n2 of the filling material 2 is 1.8. At this time, the refractive index difference between the grating unit 1 and the filling material 2 is 0.1. On this basis, see Figures 9 to 11 , respectively showing the diffraction order efficiencies corresponding to light of different wavelengths diffracting into the human eye 01 through the grating structure at different incident angles.

[0068] Specifically, Fig. 9 The figure shows the efficiency performance of each diffraction order when the light with a wavelength of 625nm 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°; Fig.10 The figure shows the efficiency performance of each diffraction order when the light with a wavelength of 525nm 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°; Fig.11 The figure shows the efficiency performance of each diffraction order when the light with a wavelength of 460nm 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°; Figures 9 to 11 Middle: 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%. At this time, the human eye 01 can hardly see the rainbow pattern. 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 diffraction efficiency, the height requirement of the grating unit 1 is relatively high, generally greater than 300nm, and the process requirement is relatively high.

[0069] It should be noted that Figures 9 to 11 The diffraction efficiency curve shown is the simulation result of the diffraction efficiency of light entering the grating structure at a set angle and then diffracting through the grating structure into the human eye.

[0070] According to the above examples of this application, the grating structure is optimized, see Figure 1 and Figure 2 , the first refractive index n1 of the grating unit 1 is 1.9, and the adjacent grating units 1 are filled with a filling material 2, and the second refractive index n2 of the filling material 2 is 1.4. At this time, the refractive index difference between the grating unit 1 and the filling material 2 is 0.5. On this basis, see Figure 12 to Figure 14 , respectively showing the diffraction order efficiencies corresponding to light of different wavelengths diffracting into the human eye 01 through the grating structure at different incident angles.

[0071] Specifically, Fig.12 The figure shows the efficiency performance of each diffraction order when the light with a wavelength of 625nm 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°; Fig.13 The figure shows the efficiency performance of each diffraction order when the light with a wavelength of 525nm 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°; Fig.14 The figure shows the efficiency performance of each diffraction order when the light with a wavelength of 460nm 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 12 to Figure 14 Middle: 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 on the upper side of the user's head, the corresponding -1T diffraction efficiency is reduced to 0.1% to 0.3%. Under this design, the human eye 01 can hardly see the rainbow pattern.

[0072] It should be noted that Figure 12 to Figure 14 The diffraction efficiency curve shown is the simulation result of the diffraction efficiency of light entering the grating structure at a set angle and then diffracting through the grating structure into the human eye.

[0073] In some examples of the present application, the grating structure satisfies: 0.2≤abs(n1-n2)≤0.3.

[0074] According to the constraints satisfied by the grating structure shown in the above example, it is a more preferred solution of the present application.

[0075] See also Figure 1 and Figure 2 , the first refractive index n1 of the grating unit 1 is 1.9, and the adjacent grating units 1 are filled with a filling material 2, and the second refractive index n2 of the filling material 2 is 1.7. At this time, the refractive index difference between the grating unit 1 and the filling material 2 is 0.2. On this basis, see Figures 15 to 17 , respectively showing the diffraction order efficiencies corresponding to light of different wavelengths diffracting into the human eye 01 through the grating structure at different incident angles.

[0076] Specifically, Fig.15 The figure shows the efficiency performance of each diffraction order when the light with a wavelength of 625nm 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°; Fig.16 The figure shows the efficiency performance of each diffraction order when the light with a wavelength of 525nm 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°; Fig.17The figure shows the efficiency performance of each diffraction order when the light with a wavelength of 460nm 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°; Figures 15 to 17 In the figure, 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%.

[0077] According to the grating structure provided in the embodiment of the present application, by adjusting the refractive index difference between the filling material 2 between the adjacent grating units 1 and the grating unit 1, for example, to 0.2 to 0.3 (including the two end point values), within the incident angle range of 55° to 80° corresponding to the top of the head, the corresponding -1T diffraction efficiency can be reduced to about 0.1% or below 0.1%. Usually, the indoor light is generally 200nits to 500nits. After the grating structure diffracts into the human eye 01, the brightness of the rainbow pattern is less than 0.5nits. At this brightness, the human eye 01 is basically imperceptible, and the rainbow pattern is fully suppressed.

[0078] It should be noted that Figures 15 to 17 The diffraction efficiency curve shown is the simulation result of the diffraction efficiency of light entering the grating structure at a set angle and then diffracting through the grating structure into the human eye.

[0079] See also Figure 12 to Figure 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 into the human eye 01 by the diffraction structure is relatively small, for example, less than 0.5 nits. The human eye 01 can basically not perceive the brightness, and the rainbow pattern is fully suppressed.

[0080] See also Figures 9 to 11 ,as well as 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 human eye 01 cannot perceive the corresponding brightness, which fully suppresses the rainbow pattern. In other words, within the refractive index difference design range of 0.1 to 0.5 (excluding the endpoint 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 pattern. 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.

[0081] The external ambient light is, for example, light emitted by indoor lamps 03, see Figure 3 .

[0082] In some examples of this application, see Figure 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≤150nm.

[0083] According to the grating structure provided by the embodiment of the present application, when filling the filling material 2 between adjacent grating units 1, in order to make the filling material 2 fill the air space 3 between adjacent grating units 1, it is necessary to cover the top surface of the plurality of grating units 1 on one side and overflow the top surface by a certain height. Generally speaking, the smaller the height of the filling material 2 overflowing the top surface of the plurality of grating units 1, the better the suppression effect on rainbow patterns.

[0084] 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.

[0085] According to the above example, the overflow height of the filling material 2 is controlled to be 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.

[0086] 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.

[0087] In some examples of the present application, the grating structure is an in-coupling grating or an out-coupling grating, and a coating is disposed on the grating structure.

[0088] A coating is plated on the surface of the grating structure, and the coating can be used to improve the diffraction efficiency of the grating structure.

[0089] For example, the grating structure is a coupling-in grating, and the coating on the coupling-in grating may be made of a metal oxide material.

[0090] For example, the grating structure is an out-coupling grating, and the coating on the out-coupling grating may be a non-metallic oxide material or a non-metallic material.

[0091] 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.

[0092] 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.

[0093] 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 step grating unit or a rectangular grating unit.

[0094] The grating structure provided in the embodiment of the present application can be applied to a diffraction optical waveguide element (lens) in a head-mounted display device. The head-mounted display device includes an AR display device and can also be used in an MR display or an XR display.

[0095] According to another aspect of the present application, the present application embodiment also provides a light guide device, see Fig.18 The light-guiding device includes a substrate 100, and a coupling-in region 101 and a coupling-out region 102 disposed on the substrate 100; the coupling-in region 101 and / or the coupling-out region 102 include the grating structure as described above.

[0096] The light guide device is, for example, a diffractive light waveguide element, and the substrate 100 is a waveguide substrate.

[0097] The coupling-in region 101 is used to couple external light into the substrate 100 .

[0098] The out-coupling region 102 is a pupil expansion and out-coupling grating, which expands the coupled light from the coupling region 101 in two dimensions, horizontally and vertically, and couples the light out.

[0099] 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.

[0100] 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 lines.

[0101] 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 a plurality of one-dimensional or two-dimensional gratings. The coupling-out region 102 can be composed of a single two-dimensional grating or a plurality of one-dimensional or two-dimensional gratings.

[0102] According to the embodiment of the present application, the grating structure may be a one-dimensional grating or a two-dimensional grating.

[0103] The direction of the one-dimensional grating vector is perpendicular to the grating lines and is the direction of its periodic change. Its length is equal to the inverse of the grating period.

[0104] The two-dimensional grating is periodically distributed in both horizontal and vertical directions.

[0105] 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 comprises a housing and the light guide device as described above.

[0106] The light guide device is, for example, a diffractive light waveguide element, which is disposed in the housing.

[0107] 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.

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

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

[0110] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A 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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