Optical structure and optical device

Abstract

The embodiment of the invention provides an optical structure and an optical device. The optical structure comprises a waveguide body; the first coupling-out grating is arranged on the waveguide body; the second coupling-out grating is arranged on the waveguide body; the third coupling-out grating is arranged on the waveguide body, and the third coupling-out grating is located between the first coupling-out grating and the second coupling-out grating; the coupling-in grating is arranged on the same side of the first coupling-out grating, the second coupling-out grating and the third coupling-out grating, and the coupling-in grating and the third coupling-out grating are arranged side by side; wherein the third coupling-out grating comprises at least two coupling-out sub-gratings, the junction of every two adjacent coupling-out sub-gratings is located in the eye box of the optical structure, and the diffraction efficiency of the coupling-in sub-grating far away from the coupling-in grating is larger than that of the coupling-out sub-grating close to the coupling-in grating. According to the scheme, the light coupling-out efficiency of the third coupling-out grating is improved, and the intensity difference of the light coupled out by the third coupling-out grating is small.

Description

[0001] This application is a divisional application of the Chinese patent application filed with the China Patent Office on July 30, 2021, with application number 202110871693.1 and invention name “Optical Structure and Optical Device”, all contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of optical technology, and in particular to an optical structure and an optical device. Background Art

[0003] Optical devices such as augmented reality (AR) devices and virtual reality (VR) devices can display images through their respective display devices. AR devices and / or VR device related technologies are increasingly being used in various fields, such as military, medical, construction, education, engineering, film and television, entertainment and other fields.

[0004] Among them, AR glasses are one of the main ways to implement AR devices. Its near-eye display system uses a series of optical imaging elements to form a distant virtual image on the pixels of the display device and project it into the human eye. AR glasses products need to meet the see-through requirements, that is, to see both the real external world and virtual information, so the imaging system cannot block the line of sight. For example, adding one or a group of optical combiners can integrate virtual information and real scenes in the form of "stacked".

[0005] In the related technologies, AR glasses have many optical implementation schemes such as refraction and reflection, reflective optical waveguide, one-dimensional diffraction optical waveguide, two-dimensional diffraction optical waveguide, holographic optical waveguide, etc. Among them, the two-dimensional diffraction optical waveguide (Two-dimensional Diffractive Waveguide, abbreviated as TDDW) is considered to be the most promising optical solution for consumer-grade AR glasses due to its thinness, high penetration of external light, good color reproduction, and large FOV.

[0006] In the related technology, the coupling-in grating of the general TDDW structure couples the light from the projection optical machine into the waveguide. The light coupled into the waveguide moves toward the coupling-out grating through total internal reflection. After reaching the coupling-out grating, it is diffracted and divided into the pupil-expanding light propagating to the left and the pupil-expanding light propagating to the right. Each time the light interacts with the coupling-out grating, a part of the energy is coupled out to the human eye, allowing the user to see the image of the projection optical machine. At present, the light coupled into different areas of the human eye by AR glasses has a large brightness difference, which seriously affects the consumer's user experience. Summary of the invention

[0007] The embodiments of the present application provide an optical structure and an optical device, which can reduce the intensity difference of the light coupled out by the third coupling grating, so that users are less likely to feel the brightness difference, thereby improving the consumer's usage experience.

[0008] The present application also provides an optical structure, which includes:

[0009] Wave conductor;

[0010] A first outcoupling grating, arranged on the waveguide;

[0011] A second outcoupling grating, disposed on the waveguide;

[0012] A third outcoupling grating is disposed on the waveguide body, and the third outcoupling grating is located between the first outcoupling grating and the second outcoupling grating; and

[0013] An in-coupling grating is arranged on the same side of the first out-coupling grating, the second out-coupling grating and the third out-coupling grating, and the in-coupling grating and the third out-coupling grating are arranged side by side;

[0014] Wherein, the third out-coupling grating includes at least two sub-out-coupling gratings, the junction of two adjacent sub-out-coupling gratings is located in the eye box of the optical structure, and the diffraction efficiency of the sub-out-coupling grating far away from the coupling-in grating is greater than the diffraction efficiency of the sub-out-coupling grating close to the coupling-in grating.

[0015] The present application also provides an optical device, which includes:

[0016] a projector configured to provide an augmented reality or virtual reality image; and

[0017] An optical structure as described in any one of the above items.

[0018] In the embodiment of the present application, the diffraction efficiency of the sub-out-grating far away from the coupling-in grating of the third coupling-out grating is greater than the diffraction efficiency of the sub-out-grating close to the coupling-in grating, so that the overall energy of the light coupled out by the third coupling-out grating can be roughly the same, and will not affect the intensity of the light coupled out by the third coupling-out grating. Therefore, the intensity difference of the light coupled out by the third coupling-out grating is small, and the user is not easily aware of the brightness difference, which improves the consumer's usage experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0020] In order to more completely understand the present application and its beneficial effects, the following description will be given in conjunction with the accompanying drawings, wherein the same figure numbers represent the same parts in the following description.

[0021] Figure 1 A schematic diagram of the optical structure provided in an embodiment of the present application.

[0022] Figure 2 A stereoscopic diagram of the optical structure provided in an embodiment of the present application.

[0023] Figure 3 A schematic diagram of the transmission of central field of view light in an optical structure provided in an embodiment of the present application.

[0024] Figure 4 A schematic diagram of the transmission of edge field light in an optical structure provided in an embodiment of the present application.

[0025] Figure 5 A schematic diagram of the principle of the optical structure light transmission process in k-space provided in an embodiment of the present application.

[0026] Figure 6 A schematic diagram of central field of view light transmitted along a plane in an optical structure provided in an embodiment of the present application.

[0027] Figure 7 A schematic diagram of the transmission of edge field light along a plane in an optical structure provided in an embodiment of the present application.

[0028] Figure 8 Schematic diagram of the application scenario of the optical structure of the embodiment of the present application.

[0029] Fig. 9 Schematic diagram of the grating vector of the first outcoupling grating in the embodiment of the present application.

[0030] Fig.10 A schematic diagram of the local structure of an optical structure and a first outcoupling grating in the optical structure provided in an embodiment of the present application.

[0031] Fig.11 A schematic diagram of the local structure of the first outcoupling grating in the optical structure provided in an embodiment of the present application.

[0032] Fig.12 A schematic diagram of the local structure of the first outcoupling grating in the optical structure provided in an embodiment of the present application.

[0033] Fig.13 A schematic diagram of the local structure of the first outcoupling grating in the optical structure provided in an embodiment of the present application.

[0034] Fig.14 A schematic diagram of the local structure of the first outcoupling grating in the optical structure provided in an embodiment of the present application.

[0035] Fig.15 A schematic diagram of the local structure of the first outcoupling grating in the optical structure provided in an embodiment of the present application.

[0036] Fig.16 A schematic diagram of an optical structure provided in an embodiment of the present application.

[0037] Fig.17 A schematic diagram of an optical structure provided in an embodiment of the present application.

[0038] Fig.18 A schematic diagram of an optical structure provided in an embodiment of the present application.

[0039] Fig.19 A schematic diagram of an optical structure provided in an embodiment of the present application.

[0040] Fig. 20 A schematic diagram of an optical structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0042] See also Figure 1 , Figure 1 A schematic diagram of the structure of an optical structure provided in an embodiment of the present application, and a reference system (x, y, z) is shown. The optical structure 200 includes a waveguide 250, an in-coupling grating 240 disposed on the waveguide, and a plurality of out-coupling gratings (out-coupling grating 210, out-coupling grating 220, and out-coupling grating 230). Among them, the waveguide 260, the in-coupling grating 240, and the plurality of out-coupling gratings (out-coupling grating 210, out-coupling grating 220, and out-coupling grating 230) of the optical structure 200 are all arranged in the xy plane.

[0043] The waveguide 250 serves as a carrier of the optical structure 200. The waveguide 250 can conduct optical signals, such as conducting optical signals by total internal reflection. The waveguide 250 may have two oppositely disposed surfaces, such as a first surface 252 and a second surface that are oppositely disposed. The second surface is disposed opposite to the first surface 252. Figure 1 is obscured from view and is not shown.

[0044] The coupling-in grating 240 is disposed on one of the surfaces of the waveguide 250, such as the first surface 252. The coupling-in grating 240 can receive an optical signal (also referred to as light) emitted from a projection optical machine (not shown in the figure), and couple the optical signal into the waveguide 250. After receiving the optical signal coupled from the coupling-in grating 240, the waveguide 250 can conduct the optical signal.

[0045] The coupling-in grating 240 may be any one of a blazed grating, a rectangular grating and a tilted grating. The coupling-in grating 240 may be a one-dimensional grating.

[0046] The plurality of outcoupling gratings may include a first outcoupling grating 210, a second outcoupling grating 220, and a third outcoupling grating 230. The first outcoupling grating 210, the second outcoupling grating 220, and the third outcoupling grating 230 are all disposed on the waveguide body 250, and the third outcoupling grating 230 is located between the first outcoupling grating 210 and the second outcoupling grating 220. In some embodiments, the first outcoupling grating 210, the second outcoupling grating 220, and the third outcoupling grating 230 are disposed on the same surface of the waveguide body 250, such as the first surface 252. It should be noted that the first outcoupling grating 210, the second outcoupling grating 220, and the third outcoupling grating 230 may also be disposed on the other surface of the waveguide body 250, that is, the second surface opposite to the first surface.

[0047] In some other embodiments, one of the first outcoupling grating 210, the second outcoupling grating 220 and the third outcoupling grating 230 may be disposed on one side of the waveguide 250, such as the first surface 252, and the other two of the first outcoupling grating 210, the second outcoupling grating 220 and the third outcoupling grating 230 may be disposed on the other side and the second surface of the waveguide 250. It is understood that any combination of the incoupling grating 240, the first outcoupling grating 210, the second outcoupling grating 220 and the third outcoupling grating 230 disposed on any side of the waveguide 250 is within the protection scope of the embodiments of the present application.

[0048] The coupling-in grating 240 of the embodiment of the present application can be arranged on the same side of the first coupling-out grating 210, the second coupling-out grating 220 and the third coupling-out grating 230, and the coupling-in grating 240 and the third coupling-out grating 230 are arranged side by side. In the embodiment of the present application, the first coupling-out grating 210 and the second coupling-out grating 220 have the same shape, and the first coupling-out grating 210 and the second coupling-out grating 220 are symmetrically arranged relative to the third coupling-out grating 230, which can also be understood as the first coupling-out grating 210 and the second coupling-out grating 220 are mirror-imaged relative to the third coupling-out grating 230. It should be noted that the shapes of the first coupling-out grating 210 and the second coupling-out grating 220 can also be different, or they can be not symmetrically arranged relative to the third coupling-out grating 230.

[0049] The waveguide 250 can move the optical signal coupled into the coupling grating 240 toward the first coupling grating 210, the second coupling grating 220 and the third coupling grating 230 through total internal reflection, and after reaching the first coupling grating 210, the second coupling grating 220 and the third coupling grating 230, it will be divided into several parts through diffraction and transmitted in multiple directions. A part of the optical signal is coupled out to the human eye, so that the user can see the picture of the projection optical machine.

[0050] See also Figure 2 , Figure 2 A three-dimensional diagram of the optical structure provided in the embodiment of the present application, and Figure 2 The transmission of the optical signal after the incident light of the central field of view is diffracted is shown, and the reference system (x, y, z) is shown. After the central field of view light is incident on the coupling-in grating 240, the coupling-in grating 240 transmits the light 201 toward the third coupling-out grating 230 through the waveguide 250. After the light 201 interacts with the third coupling-out grating 230, it is diffracted and split into four light beams, namely, light 2011, light 2012, light 2013 and light 2014.

[0051] Light 2011 moves along the original path of light 201. It can be understood that after the light 201 interacts with the third out-coupling grating 230 and is diffracted, it is split into four light beams. During the process of the light 201 moving along the original path of light 201, light 2011 interacts with the third out-coupling grating 230 for many times, and each interaction is split into four light beams after diffraction. That is, during the process of the light 2011 moving along the original path of light 201, light 2011 interacts with the third out-coupling grating 230 for many times, and is split into multiple light beams 2013, multiple light beams 2014, multiple light beams 2014, and multiple light beams 2011 after diffraction. Since multiple light beams 2011 all move along the original path of light 201, they are displayed as one light beam. Each time the light 2011 interacts with the third out-coupling grating 230 once, the energy of the light moving along the original path will decrease.

[0052] The light 2012 is directly coupled out from the third out-coupling grating 230, which can be understood as the light 2012 being coupled out in the positive direction toward z based on the xy plane. In the embodiment of the present application, all the light directly coupled out from the third out-coupling grating 230 is defined as the light 2012. It can be understood that the energies of different light directly coupled out from different positions of the third out-coupling grating 230 are different.

[0053] After the light 2013 interacts with the first out-coupling grating 210, it is split into two light beams by diffraction, namely, light beam 2013A and light beam 2013B. Light beam 2013A is directly coupled out from the first out-coupling grating 210, which can be understood as light beam 2013A being coupled out in the positive direction toward z based on the xy plane. Light beam 2013B moves along the original path of light beam 2013. In the embodiment of the present application, the light beam propagating from the third out-coupling grating 230 toward the first out-coupling grating 210 is defined as light beam 2013, and there are multiple light beams 2013, and each light beam 2013 is split into multiple light beams 2013A and multiple light beams 2013B by diffraction after interacting with the first out-coupling grating 210. It can be understood that different light beams 2013 have different energies, different light beams 2013A have different energies, and different light beams 2013B have different energies.

[0054] After interacting with the second out-coupling grating 220, the light 2014 is split into two light beams by diffraction, namely, the light 2014A and the light 2014B. The light 2014A is directly coupled out from the second out-coupling grating 210, which can be understood as the light 2014A is coupled out in the positive direction toward z based on the xy plane. The light 2014B moves along the original path of the light 2014. In the embodiment of the present application, the light propagating from the third out-coupling grating 230 toward the second out-coupling grating 220 is defined as the light 2014. There are multiple light beams 2014, and each light beam 2014 is split into multiple light beams 2014A and multiple light beams 2014B by diffraction after interacting with the second out-coupling grating 220. It can be understood that different light beams 2014 have different energies, different light beams 2014A have different energies, and different light beams 2014B have different energies.

[0055] The light coupled out in the positive direction of z based on the xy plane will enter the human eye, allowing the user to see the image of the projection machine. Figure 2 ,like Figure 2 In the example shown, light 2012 coupled out from the third outcoupling grating 230 in the positive direction of z will enter the human eye, light 2013A coupled out from the first outcoupling grating 210 in the positive direction of z will enter the human eye, and light 2014A coupled out from the second outcoupling grating 220 in the positive direction of z will enter the human eye.

[0056] It should be noted that Figure 2 The light 2011, light 2012, light 2013, and light 2014 shown are exemplary, and do not limit the number of light rays coupled out of the optical structure 200. Figure 2 A portion of the light when the optical structure 200 of the embodiment of the present application is coupled out is shown, and the remaining light is not shown.

[0057] See also Figure 3 and Figure 4 , Figure 3 A schematic diagram of the transmission of central field light in an optical structure provided in an embodiment of the present application, Figure 4 Schematic diagram of the transmission of edge field light in an optical structure provided by an embodiment of the present application. The coupling-in grating 240 transmits the coupled-out light 201 to the third coupling-out grating 230 through the waveguide 250, and interacts with the third coupling-out grating 230 to split into multiple light rays such as light 2011, light 2012, light 2013 and light 2014, wherein the transmission directions of the light 2011, light 2012, light 2013 and light 2014 can be referred to Figure 2 It should be noted that in the xy plane, the light 2012 is replaced by a dot. The light 2013 interacts with the first outcoupling grating 210 to split into multiple light rays such as the light 2013A and the light 2013B. The light 2013A and the light 2013B can be referred to in Figure 2 It should be noted that in the xy plane, the light 2013A is replaced by a dot. The light 2014 interacts with the second outcoupling grating 220 to split into multiple light rays such as the light 2014A and the light 2014B. The light 2014A and the light 2014B can be referred to in Figure 2 It should be noted that in the xy plane, the light ray 2014A is replaced by a dot. Figure 3 and Figure 4 As can be seen from the diagram, each dot represents a ray of light interacting with an outcoupling grating, and the light represented by the dot can be incident on the human eye.

[0058] Figure 3 and Figure 4 It shows that each outcoupling grating can couple out multiple light rays along the positive direction of the z-axis.

[0059] It should be noted that Figure 3 and Figure 4 Only a portion of the light represented by the middle dot will enter the human eye.

[0060] See also Figure 5 , Figure 5 A schematic diagram of the principle of the optical structure light transmission process in k-space provided in an embodiment of the present application, and a reference system (kx, ky, kz) is shown. Figure 5The two circle radii shown are respectively the environment refractive index and the waveguide refractive index, wherein the radius of the small circle, i.e. the radius of the inner circle, is the environment refractive index, and the radius of the large circle, i.e. the radius of the outer circle, is the waveguide refractive index. The rectangle represents the field of view (FOV), and each rectangle represents a field of view. Rectangles at different positions represent different states of the field of view light. For example, the rectangle at the center of the ring represents the field of view light incident or coupled out (light 2012, light 2013A, light 2014A) from the projector to the waveguide body 250, and the rectangle inside the ring (i.e. between the two circles) represents the field of view light propagating in the waveguide body 240 after being coupled by the grating (the first coupling out grating 210, the second coupling out grating 220, and the coupling in grating 240). If the field of view is located in the small circle, it means that the light can be coupled out of the waveguide body 250, if the field of view is located in the ring, it means that the light propagates in the waveguide body 250, and if the field of view is located outside the large circle, it means that the light does not actually exist. At the origin of the coordinate field, the light 201 is diffracted by the coupling grating 240 and coupled into the waveguide 250 by k1. Then, the light 201 is changed to 6 different positions around its k space through the 6 diffraction components k22 of the third coupling grating 230. Among them, the light 2013 and the light 2014 are still in the ring, which means that they will be propagated to the left and right along the kx axis respectively by total internal reflection and become pupil expansion light. Another part of the light will be translated upward by diffraction and overlap with the original incident image, which means that they (such as light 2012) will be directly coupled out. The remaining 3 positions are all outside the ring, which means that these 3 diffraction components do not exist. Not all the energy of the light 201 is diffracted. On the contrary, it will retain most of the energy unchanged, which means that most of the energy continues to be propagated by total internal reflection along the propagation direction of the light 201.

[0061] In the embodiment of the present application, the area where the optical structure 200 is coupled out and injected into the human eye is defined as an eye box 260. That is, the light in the eye box 260 and coupled out along the positive direction of the z-axis will be injected into the human eye.

[0062] The eye box will be described below.

[0063] See also Figures 6 to 8 , Figure 6 A schematic diagram of the central field of view light provided in an embodiment of the present application being transmitted along a plane in an optical structure, Figure 7 A schematic diagram of the transmission of edge field light along a plane in an optical structure provided in an embodiment of the present application, Figure 8Schematic diagram of the application scenario of the optical structure of the embodiment of the present application. Assume that the incident field of view has an angle range of -a° to a° with the z-axis in the yz plane, that is, the incident maximum field of view F2 has an angle range of a° with the z-axis in the yz plane, and the incident minimum field of view F1 has an angle range of -a° with the z-axis in the yz plane. The distance from the human eye to the waveguide 250 (eyerelief) is b, that is, the distance from the Eyebox plane or the human eye observation plane to the waveguide 250 is b. Then the length of the eyebox 260 in the y-axis direction is B, where B = A-2b*tan(a).

[0064] Wherein A is the minimum length of the first outcoupling grating 210 in the y-axis direction, and A may also be the minimum length of the second outcoupling grating 210 in the y-axis direction. It should be noted that in the embodiment of the present application, the minimum length of the first outcoupling grating 210 in the y-axis direction is the same as the minimum length of the second outcoupling grating 220 in the y-axis direction.

[0065] In an optional embodiment of the present application, the center of the eye box 260 may coincide with the center of the third outcoupling grating 230 .

[0066] Please continue reading Figure 2 , Figure 3 and Figure 6 When the central field of view light is incident on the optical structure 200, a portion of the light coupled out by the first coupling grating 210, the second coupling grating 220 and the third coupling grating 230, such as the light 2012, the light 2013A and the light 2014A, will be within the eye box 260, that is, will be incident on the human eye.

[0067] Please continue reading Figure 4 and Figure 7 When the edge field light is incident on the optical structure 200, only a part of the light 2012 and the light 2014A coupled out by the second coupling grating 220 and the third coupling grating 230 will be in the eye box 260, while the light coupled out by the first coupling grating 210, such as the light 2013A, is basically not in the eye box 260. In other words, the energy of the light coupled out by the second coupling grating 220 and the third coupling grating 230 is used, and the energy of the light coupled out by the first coupling grating 210 is wasted, which often results in poor exit pupil uniformity of the edge field.

[0068] Moreover, under the waveguide architecture in the relevant technology, the uniformity of the exit pupil of the edge field of view is significantly worse than that of the central field of view. This means that when watching the projection light machine screen at certain eyebox positions, the difference in brightness between the central field of view and the edge field of view will be relatively large, causing discomfort to users.

[0069] Based on this, the first coupling grating 210 defined in the embodiment of the present application adopts a two-dimensional grating structure and has a plurality of first grids, and each grid is asymmetric in shape, so that the efficiency of light propagated in the first direction by the first coupling grating 210 is higher than the efficiency of light propagated in the second direction by the first coupling grating 210. The energy of the wasted part of the light coupled out by the first coupling grating 210 is smaller than the energy of other light, thereby improving the exit pupil brightness and uniformity of each field of view, and reducing the difference between the energies of each field of view. For example, the exit pupil brightness and uniformity of the edge field of view can be improved, and the difference between the energy of the edge field of view and the energy of the center field of view can be reduced. In particular, when the optical structure 200 is applied to head-mounted display products such as AR, it can enhance the suppression of the rainbow effect of sunlight and improve the image quality of the product.

[0070] The first direction is the direction from the first outcoupling grating 210 to the second outcoupling grating 220, such as Figure 1 The second direction is the direction from the second outcoupling grating 220 to the first outcoupling grating 210, such as Figure 1 The positive direction of the x-axis is shown. In the embodiment of the present application, the first direction is opposite to the second direction.

[0071] See also Fig. 9 , Fig. 9 Schematic diagram of grating vectors of the first out-coupling grating of the embodiment of the present application. The first out-coupling grating 210 has multiple diffraction vectors, including (1,1), (1,0), (0,1), (0,-1), (-1,0), (-1,-1). The diffraction efficiency of the (1,0) and (-1,0) orders of the first out-coupling grating 210 diffraction orders is significantly higher than that of the (0,1) and (0,-1) orders. When the light 201 is incident on the first out-coupling grating 210, the light 2014B is generated by the (-1,0) order diffraction of the first out-coupling grating 210, and the light 2013B is generated by the (0,1) order diffraction of the first out-coupling grating 210. Therefore, the efficiency of the light 2014B propagating to the left (first direction) in the figure is much higher than that of the light 2013B propagating to the right (second direction) in the figure.

[0072] To explain in detail that the asymmetric shape of the first grating 212 in the embodiment of the present application can make the light efficiency of the first outcoupling grating 210 propagating in the first direction higher than the light efficiency of the first outcoupling grating 210 propagating in the second direction, the first outcoupling grating 210 is described below in conjunction with the schematic diagram.

[0073] See also Figures 10 to 13 , Fig.10 A schematic diagram of a local structure of an optical structure and a first outcoupling grating in the optical structure provided in an embodiment of the present application, Fig.11A schematic diagram of a local structure of a first outcoupling grating in an optical structure provided in an embodiment of the present application, Fig.12 A schematic diagram of a local structure of a first outcoupling grating in an optical structure provided in an embodiment of the present application, Fig.13 This is a schematic diagram of the partial structure of the first outcoupling grating in the optical structure provided in the embodiment of the present application. Fig.10 The local structure M of the first outcoupling grating 210 is defined as a first portion M. That is, the plurality of first grids 212 in the first portion M are a portion of the first grids 212 of the first outcoupling grating 210 .

[0074] The shapes of all the first grids 212 in the plurality of first grids 212 of the first outcoupling grating 210 may be substantially the same. For example, each first grid 212 has four vertices such as vertex c, vertex d, vertex e, and vertex f, and the four vertices may form a first diagonal line ce and a second diagonal line df. The length of the first diagonal line ce is greater than the length of the second diagonal line df, and the angle θacx between the first diagonal line ac and the third outcoupling grating 230 in the third direction is an acute angle, and the angle θacy between the second diagonal line bd and the third outcoupling grating in the third direction is an obtuse angle.

[0075] The third direction is the direction from the third out-coupling grating 230 to the in-coupling grating 240 .

[0076] In an optional embodiment of the present application, the first grids 212 of the same shape are periodically arranged in a hexagonal lattice on the xy plane, and have two periodic directions, namely periodic direction a and periodic direction b, and the periodic direction a and the periodic direction b form an angle of 30°. The periodic direction a is parallel to the y-axis, and the distance between the two first grids 212 along the periodic direction a is Pa. The periodic direction b forms an angle of 30° with the y-axis, and the distance between the two first grids 212 along the periodic direction b is Pb. Pa can be 0.4μm to 3μm, and Pb can be 0.2μm to 2μm. Pa and Pb must satisfy the relationship: Pa=Pb / 2cos(30°).

[0077] The asymmetric shape adopted by the first grid 212 in the embodiment of the present application can also be understood as the first grid 212 being a shape in which each first grid 212 is asymmetric about the x-axis and the y-axis, and the first diagonal line ce of the first grid 212 is always longer than the second diagonal line df, and the angle θacy between the first diagonal line ce and the positive direction of the y-axis is an obtuse angle, and the angle θacx between the first diagonal line ce and the positive direction of the x-axis is an acute angle.

[0078] The first outcoupling grating 210 has a plurality of grid groups 211, each grid group 211 includes a plurality of first grids 212, and each first grid 212 in each grid group 211 intersects with its adjacent first grid 212, and each grid group 211 is spaced apart from each other. In an optional embodiment of the present application, each grid group 211 is parallel to each other. Each first grid in each grid group 211 is arranged along the sixth direction. It can also be understood that each first grid 212 intersects with the next first grid 212 adjacent in the oblique direction at the upper right and lower left.

[0079] The sixth direction is the direction of the seventh direction rotated 30 degrees clockwise, and the seventh direction is the direction from the third outcoupling grating 230 to the incoupling grating 240. It should be noted that the seventh direction can also be understood as the positive direction of Pa, that is, the sixth direction is the direction of Pb1.

[0080] It should be noted that the number of vertices of the first grid 211 is not limited to four, for example, the first grid includes at least five vertices, that is, the first grid 211 may have 5 or more vertices. The present embodiment of the application is described by taking 5 vertices as an example.

[0081] See also Fig.14 , Fig.14 A schematic diagram of the local structure of the first out-coupling grating in the optical structure provided in an embodiment of the present application. The vertices of the first grating 212 include two vertices (vertex c and vertex d) close to the third out-coupling grating 230 and two vertices (vertex e and vertex f) away from the third out-coupling grating 230, the two vertices (vertex c and vertex d) close to the third out-coupling grating 230 and the two vertices (vertex e and vertex f) away from the third out-coupling grating 230 can form a third diagonal line ce and a fourth diagonal line df, the length of the third diagonal line ce is greater than the length of the fourth diagonal line df, and the angle between the third diagonal line ce and the third out-coupling grating 230 in the fourth direction is an acute angle, and the angle between the fourth diagonal line df and the third out-coupling grating 230 in the fourth direction is an obtuse angle.

[0082] The fourth direction is the direction from the third out-coupling grating 230 to the in-coupling grating 240. That is, the fourth direction can be understood as the third direction. The third diagonal line ce and the fourth diagonal line df can be referred to as Figures 11 to 13 The third diagonal line ce and the fourth diagonal line df are shown in FIG. Figures 11 to 13 The first grid 212 and the grid group 211 are shown and are not described in detail herein.

[0083] It should be noted that the number of vertices of the first grid 211 is not limited to four, five or more than five. For example, the first grid includes three vertices, that is, the first grid 211 may have three vertices.

[0084] See also Fig.15 , Fig.15 A schematic diagram of the local structure of the first out-coupling grating in the optical structure provided in an embodiment of the present application. The vertices of the first grid 212 include vertex c, vertex d and vertex e, which are connected to each other to form a first vertex connecting edge cd, a second vertex connecting edge de and a third vertex connecting edge ce, the first vertex connecting edge cd is close to the third out-coupling grating 230, the second vertex connecting edge de is far away from the third out-coupling grating 230, the length of the first vertex connecting edge cd is greater than the length of the second vertex connecting edge de, and the angle between the first vertex connecting edge cd and the third out-coupling grating 230 in the fifth direction is an acute angle, and the angle between the second vertex connecting edge de and the third out-coupling grating 230 in the fifth direction is an obtuse angle

[0085] The fifth direction is the direction from the third out-coupling grating 230 to the in-coupling grating 240. That is, the fifth direction can be understood as the third direction. Figures 11 to 13 The third diagonal line ce and the fourth diagonal line df are shown in FIG. Figures 11 to 13 The first grid 212 and the grid group 211 are shown and are not described in detail herein.

[0086] In the embodiment of the present application, the first out-coupling grating 210 and the second out-coupling grating 220 have the same shape, and the first out-coupling grating 210 and the second out-coupling grating 220 are symmetrically arranged relative to the third out-coupling grating 230. It can also be understood that the first out-coupling grating 210 and the second out-coupling grating 220 are mirror-imaged relative to the third out-coupling grating 230. That is, the multiple grids in the second out-coupling grating 220 are all two-dimensional gratings, and the shape and arrangement of the grid structure of each two-dimensional grating are the same as those of the first grating 212. For example, the second out-coupling grating 220 is a two-dimensional grating having multiple second grids, and all the second grids in the second out-coupling grating 220 have the same shape and the same arrangement as all the first grids in the first out-coupling grating 210. For specific shapes and arrangements, please refer to Figures 11 to 15 , I will not go into details here.

[0087] The third outcoupling grating 230 is a two-dimensional grating having a plurality of third grids, and the third grids are symmetrical, such as a two-dimensional grating with a bilateral symmetrical shape, so that the efficiency of the light propagating to the left is relatively high compared with the efficiency of the light propagating to the right, which is beneficial to increase the size of the eye box 260 at the edge field of view. The third grids can be arranged in a hexagonal lattice, and the grating vector can be referred to Fig. 9, and its (1,1)-order diffraction vector is parallel to the y-axis. The third grid may be any shape symmetrical along the y-axis, such as a circle, a positive direction, a rhombus, a hexagon, an octagon, etc. The area of ​​the third outcoupling grating 230 may be a rectangle, for example, the lateral width in the x-axis direction may be 1 mm to 15 mm, and the longitudinal width in the y-axis direction may be 20 mm to 35 mm.

[0088] In an optional embodiment of the present application, the grating periods of the first out-coupling grating 210, the second out-coupling grating 220 and the third out-coupling grating 230 are equal, and the refractive index of any one of the first out-coupling grating 210, the second out-coupling grating 220 and the third out-coupling grating 230 and the waveguide 250 is 1.5-3. The grating period of the coupling-in grating 240 is half of the grating period of any one of the first out-coupling grating 210, the second out-coupling grating 220 and the third out-coupling grating 230 in a direction perpendicular to the first direction. In other words, the grating period of the coupling-in grating 240 is half of the grating period of any one of the first out-coupling grating 210, the second out-coupling grating 220 and the third out-coupling grating 230 in the y-axis direction.

[0089] The materials of the coupling-in grating 240 , the first coupling-out grating 210 , the second coupling-out grating 220 and the third coupling-out grating 230 can all be silicon, plastic, glass, polymer or a combination of the above materials.

[0090] Please continue reading Figure 2 , the display brightness at each position in Eyebox260 is determined by the intensity of the coupled light at that position, so the intensity of light 2012, light 2013A, and light 2014A directly determines the display quality of Eyebox260. In actual applications, the intensity of light 2012 is much weaker than that of light 2013A and light 2014A, which results in an obvious dark area at the position corresponding to light 212 in Eyebox260, which greatly affects the user experience of consumers. The reason why the intensity of light 212 is weaker than that of light 213A and light 214A is that the coupling efficiency of the third coupling grating 230 cannot be set too large, otherwise the main light 201 will decay too quickly during the propagation process, and the light 201 that decays too quickly will cause the light intensity difference between the light 2012, which will eventually cause more serious uneven brightness of Eyebox260.

[0091] Based on this, the embodiment of the present application proposes an optical structure to improve the efficiency of the light outcoupling of the third outcoupling grating 230 without causing intensity differences between the light rays 2012. For example, the optical structure 200 of the embodiment of the present application divides the third outcoupling grating 230 into multiple areas along the y-axis, and the efficiency of different areas along the y-axis gradually increases. In this way, although the main light ray 201 will decay during the propagation process, the efficiency of the outcoupling grating corresponding to 2012 and even more subsequent outcoupling lights can be gradually improved. In this way, although the main light ray 201 decays faster due to the increase in the efficiency of the third outcoupling grating 230, the energy difference between the light ray 2012 and even more subsequent outcoupling lights can be reduced, so that the energy of the light ray 2012 is closer to the light ray 2013A and the light ray 2014A, and the intensity difference between the light ray 2012 is reduced, and finally the brightness and brightness uniformity of the Eyebox 260 are improved at the same time, and the energy and brightness uniformity of the Eyebox 260 are greatly improved. In summary, the embodiment of the present application introduces the technology of partitioning the third out-coupling grating 230 into multiple gratings, which solves the above-mentioned problems and greatly improves the energy and brightness uniformity of Eyebox 260. Therefore, the embodiment of the present application has great implementation significance and is a diffraction waveguide architecture with excellent performance.

[0092] The third out-coupling grating 230 of the embodiment of the present application includes at least two sub-out-coupling gratings, and the junction of two adjacent sub-out-coupling gratings is located in the eye box 260 of the optical structure 200, and the diffraction efficiency of the sub-out-coupling grating far from the coupling-in grating 240 is greater than the diffraction efficiency of the sub-out-coupling grating close to the coupling-in grating 240. Therefore, the overall energy of the light coupled out by the third out-coupling grating 230 can be roughly the same, or it can be understood that the energy of the light coupled out by each sub-out-coupling grating of the third out-coupling grating 230 is roughly the same. And it will not affect the intensity of the light coupled out by the third out-coupling grating 230. The following is a detailed description with reference to the drawings.

[0093] In an optional implementation of the embodiment of the present application, the grating depth of the sub-outcoupling grating far from the coupling-in grating 240 is greater than the grating depth of the sub-outcoupling grating close to the coupling-in grating 240, so that the diffraction efficiency of the sub-outcoupling grating far from the coupling-in grating 240 can be greater than the diffraction efficiency of the sub-outcoupling grating close to the coupling-in grating 240. That is, the deeper the grating of the optical structure 200 defined in an optional implementation of the present application, the higher its diffraction efficiency.

[0094] See also Fig.16 and Fig.17 , Fig.16 A schematic diagram of an optical structure provided in an embodiment of the present application, Fig.17Schematic diagram of an optical structure provided in an embodiment of the present application. The third outcoupling grating 230 of the optical structure 200 may include three sub-outcoupling gratings, and at least a portion of each sub-outcoupling grating is located in the eye box 260. For example, the third outcoupling grating 230 includes a first sub-outcoupling grating 231 partially located on one side of the eye box 260, a second sub-outcoupling grating 232 partially located on the other side of the eye box 260, and a third sub-outcoupling grating 233 completely located in the eye box 260.

[0095] The length of the first out-coupling grating 231 along the arrangement direction of all out-coupling gratings is greater than the length of the third out-coupling grating 233 in the eye box 260 along the arrangement direction of all out-coupling gratings. Alternatively, it can be understood that the length of the first out-coupling grating 231 along the y-axis direction is greater than the length of the third out-coupling grating 233 in the eye box 260 along the y-axis direction.

[0096] The length of the second outgoing grating 232 along the arrangement direction of all outgoing gratings is greater than the length of the third outgoing grating 233 in the eye box 260 along the arrangement direction of all outgoing gratings. Alternatively, it can be understood that the length of the second outgoing grating 232 along the y-axis direction is greater than the length of the third outgoing grating 233 in the eye box 260 along the y-axis direction.

[0097] In an optional implementation of the present application, the length of the second sub-outcoupling grating 232 along the arrangement direction of all the sub-outcoupling gratings may be the same as the length of the first sub-outcoupling grating 231 along the arrangement direction of all the sub-outcoupling gratings. The first sub-outcoupling grating 231 and the second sub-outcoupling grating 232 may be symmetrically arranged relative to the third sub-outcoupling grating 233. It should be noted that the lengths of the first sub-outcoupling grating 231 and the second sub-outcoupling grating 232 along the arrangement direction of all the sub-outcoupling gratings may also be unequal.

[0098] In the embodiment of the present application, the length of the first sub-outcoupling grating 231 along the arrangement direction of all the sub-outcoupling gratings and the length of the second sub-outcoupling grating 232 along the arrangement direction of all the sub-outcoupling gratings are both greater than the length of the third sub-outcoupling grating 233 along the arrangement direction of all the sub-outcoupling gratings. In an optional embodiment of the present application, the ratio of the length of the first sub-outcoupling grating 231 along the arrangement direction of all the sub-outcoupling gratings to the length of all the sub-outcoupling gratings is P1, that is, the ratio of the length of the first sub-outcoupling grating 231 along the y-axis direction to the length of the third outcoupling grating 230 along the y-axis direction is P1. The ratio of the length of the third sub-outcoupling grating 233 along the arrangement direction of all the sub-outcoupling gratings to the length of all the sub-outcoupling gratings is P2, that is, the ratio of the length of the third sub-outcoupling grating 233 along the y-axis direction to the length of the third outcoupling grating 230 along the y-axis direction is P2. P1 is greater than or equal to 30% and less than or equal to 45%, P2 is greater than or equal to 10% and less than 30%.

[0099] In an optional embodiment of the present application, the portion of the first outcoupling grating 231 located in the eye box 260 has the same size as the portion of the second outcoupling grating 232 located in the eye box 260. Figure 5 and Figure 6 The boundary of the sub-coupling gratings of the third outcoupling grating 230 is located within a range of B / 2 above and below the center of the third outcoupling grating 230 .

[0100] In an optional implementation of the present application, the diffraction efficiency of all sub-out-gratings increases in proportion from a sub-out-grating closest to the coupling-in grating 240, such as the first sub-out-grating 231, to a sub-out-grating farthest from the coupling-in grating 240, such as the second sub-out-grating 232. It can also be understood that the diffraction efficiency of all sub-out-gratings increases in proportion along the positive direction of the y-axis. For example, the diffraction efficiency of the third sub-out-grating 233 is n times that of the first sub-out-grating 231, where n is greater than 1. The diffraction efficiency of the second sub-out-grating 232 is n times that of the third sub-out-grating 233. Thereby, it can be ensured that the energy of the light coupled out by each sub-diffraction grating is not much different.

[0101] It should be noted that Fig.16 and Fig.17 The structure of the third outcoupling grating 230 being divided into three regions is merely exemplary and does not limit the number of regions of the third outcoupling grating 230. For example, the third outcoupling grating 230 may include two sub-outcoupling gratings, four sub-outcoupling gratings, five sub-outcoupling gratings, etc. Sub-outcoupling gratings with a greater number will not be described one by one here.

[0102] It should also be noted that when the number of sub-outcoupling gratings of the third outcoupling grating 230 is greater than three, such as four or five, it is still satisfied that the junction of two adjacent sub-outcoupling gratings of all sub-outcoupling gratings of the third outcoupling grating 230 is located in the eye box 260 of the optical structure 200, and the diffraction efficiency of the sub-outcoupling grating far from the coupling-in grating 240 is greater than the diffraction efficiency of the sub-outcoupling grating close to the coupling-in grating 240. Similarly, the overall energy of the light coupled out by the third outcoupling grating 230 can be roughly the same, or it can be understood that the energy of the light coupled out by each sub-outcoupling grating of the third outcoupling grating 230 is roughly the same. And it will not affect the intensity of the light coupled out by the third outcoupling grating 230.

[0103] When the number of sub-outcoupling gratings of the third outcoupling grating 230 is greater than three, such as four or five. At least a portion of all sub-gratings of the third outcoupling grating 230 can be located in the eye box 260. That is, the third outcoupling grating 230 includes a outcoupling grating partially located on one side of the eye box 260, a sub-outcoupling grating partially located on the other side of the eye box 260, and two or more sub-outcoupling gratings completely located in the eye box 260. The sum of the lengths of all sub-outcoupling gratings completely located in the eye box 260 along the arrangement direction of all sub-outcoupling gratings of the third outcoupling grating 230 is less than the length of any sub-outcoupling grating partially located outside the eye box 260 along the arrangement direction of all sub-outcoupling gratings of the third outcoupling grating 230. It can also be understood that the sum of the lengths of all sub-outcoupling gratings completely located in the eye box 260 along the y-axis direction is less than the length of any sub-outcoupling grating partially located outside the eye box 260 along the y-axis direction.

[0104] and Fig.16 and Fig.17 In comparison, the ratio of the sum of the lengths of at least two sub-outcoupling gratings of the third outcoupling grating 230 along the y-axis direction and the length of the third outcoupling grating 230 along the y-axis direction is P2. Fig.16 and Fig.17 , I will not go into details here.

[0105] See also Fig.18 , Fig.18 A schematic diagram of an optical structure provided in an embodiment of the present application. Fig.18 The third outcoupling grating 230 is shown to include four sub-outcoupling gratings, namely a first sub-outcoupling grating 231, a second sub-outcoupling grating 232, a third sub-outcoupling grating 233 and a fourth sub-outcoupling grating 234, wherein the first sub-outcoupling grating 231 and the second sub-outcoupling grating 232 can refer to the above content and are not described in detail here. The third sub-outcoupling grating 233 and the fourth sub-outcoupling grating are both located in the eye box 260.

[0106] See also Fig.19 , Fig.19 A schematic diagram of an optical structure provided in an embodiment of the present application. Fig.19 The third outcoupling grating 230 is shown to include five sub-outcoupling gratings, namely the first sub-outcoupling grating 231, the second sub-outcoupling grating 232, the third sub-outcoupling grating 233, the fourth sub-outcoupling grating 234 and the fifth sub-outcoupling grating 235, wherein the first sub-outcoupling grating 231 and the second sub-outcoupling grating 232 can refer to the above content and will not be described again. The third sub-outcoupling grating 233, the fourth sub-outcoupling grating and the fifth sub-outcoupling grating are all located in the eye box 260.

[0107] Considering that the intensity of light 2012, light 2013A, and light 2014A directly determines the display quality of Eyebox260, and in actual application, the intensity of light 2012 is significantly weaker than light 2013A and light 2014A. In some embodiments of the present application, the third coupling grating 230 that can couple out light 2012 is set in different regions, so that the energy of light 2012 can be closer to light 2013A and light 2014A, while the intensity difference between light 2012 is reduced, and finally the brightness and brightness uniformity of Eyebox260 are improved at the same time, and the energy and brightness uniformity of Eyebox260 are greatly improved. In actual application, the energy of light 2013A and light 2014A will also be lost as the light propagates. In order to further improve the brightness and brightness uniformity of Eyebox260, in some optional implementations of the present application, the first coupling grating 210 and the second coupling grating 220 are also set in different regions. Detailed description is given below in conjunction with the diagram.

[0108] See also Fig. 20 , Fig. 20 A schematic diagram of an optical structure provided in an embodiment of the present application. Fig. 20 The first outcoupling grating 210, the second outcoupling grating 220 and the third outcoupling grating 230 in the optical structure 200 are all arranged in different regions. Figures 16 to 19 , I will not go into details here.

[0109] The first out-coupling grating 210 includes at least two sub-out-coupling gratings, and the number of the sub-out-coupling gratings of the first out-coupling grating 210 is the same as the number of the sub-out-coupling gratings of the third out-coupling grating 230, such as three. And the junction of two adjacent sub-out-coupling gratings in the first out-coupling grating 210 is located in the eye box 260 of the optical structure 200. The diffraction efficiency of the sub-out-coupling grating far from the coupling-in grating 240 in the first out-coupling grating 210 is greater than the diffraction efficiency of the sub-out-coupling grating close to the coupling-in grating 240. Thereby, the overall energy of the light coupled out by the first out-coupling grating 210 can be made roughly the same, or it can be understood that the energy of the light coupled out by each sub-out-coupling grating of the first out-coupling grating 210 is roughly the same. And it will not affect the intensity of the light coupled out by the first out-coupling grating 210.

[0110] Fig. 20The sub-outcoupling gratings of the first outcoupling grating 210 shown are illustrated by taking three as an example. The first outcoupling grating 210 includes a first sub-outcoupling grating 211, a second sub-outcoupling grating 212 and a third sub-outcoupling grating 213. It should be noted that the first sub-outcoupling grating 211 can refer to the first sub-outcoupling grating 231, the second sub-outcoupling grating 212 can refer to the third sub-outcoupling grating 233, and the third sub-outcoupling grating 213 can refer to the second sub-outcoupling grating 232, which will not be described in detail here. It should be noted that when the number of sub-regions of the first outcoupling grating 210 and the number of sub-regions of the third outcoupling grating 230 are both greater than three, they can refer to Fig.18 and Fig.19 , two sub-coupling gratings, three sub-coupling gratings or more sub-coupling gratings are arranged between the first sub-coupling grating 211 and the third sub-coupling grating 213, and their arrangement method is the same as the arrangement method of the sub-coupling gratings of the third outcoupling grating 230, which will not be repeated here.

[0111] The second out-coupling grating 220 includes at least two sub-out-coupling gratings, and the number of the sub-out-coupling gratings of the second out-coupling grating 220 is the same as the number of the sub-out-coupling gratings of the third out-coupling grating 230, such as three. And the junction of two adjacent sub-out-coupling gratings in the second out-coupling grating 220 is located in the eye box 260 of the optical structure 200. The diffraction efficiency of the sub-out-coupling grating far from the coupling-in grating 240 in the second out-coupling grating 220 is greater than the diffraction efficiency of the sub-out-coupling grating close to the coupling-in grating 240. Thereby, the overall energy of the light coupled out by the second out-coupling grating 220 can be made roughly the same, or it can be understood that the energy of the light coupled out by each sub-out-coupling grating of the second out-coupling grating 220 is roughly the same. And it will not affect the intensity of the light coupled out by the second out-coupling grating 220.

[0112] Fig. 20 The sub-outcoupling gratings of the second outcoupling grating 220 shown are illustrated by taking three as an example. The second outcoupling grating 210 includes a first sub-outcoupling grating 221, a second sub-outcoupling grating 222 and a third sub-outcoupling grating 223. It should be noted that the first sub-outcoupling grating 221 can refer to the first sub-outcoupling grating 231, the second sub-outcoupling grating 222 can refer to the third sub-outcoupling grating 233, and the third sub-outcoupling grating 223 can refer to the second sub-outcoupling grating 232, which will not be described in detail here. It should be noted that when the number of sub-regions of the second outcoupling grating 220 and the number of sub-regions of the third outcoupling grating 230 are both greater than three, they can refer to Fig.18 and Fig.19 , two sub-coupling gratings, three sub-coupling gratings or more sub-coupling gratings are arranged between the first sub-coupling grating 221 and the third sub-coupling grating 223, and their arrangement method is the same as the arrangement method of the sub-coupling gratings of the third outcoupling grating 230, which will not be repeated here.

[0113] It is understandable that in some other embodiments of the present application, only one of the first outcoupling grating 210, the second outcoupling grating 220 and the third outcoupling grating 230 is arranged in a divided area manner, which is also within the scope defined by the embodiments of the present application. And only two of the first outcoupling grating 210, the second outcoupling grating 220 and the third outcoupling grating 230 are arranged in a divided area manner, which is also within the scope defined by the embodiments of the present application.

[0114] When the third outcoupling grating 230 includes a plurality of sub-outcoupling gratings, the first outcoupling grating 210, the second outcoupling grating 220 and the third outcoupling grating 230 may all be two-dimensional gratings, such as Figures 1 to 15 The contents shown are not repeated here. It should be noted that, when the third out-coupling grating 230 includes a plurality of sub-out-coupling gratings, the first out-coupling grating 210 and the second out-coupling grating 220 may also adopt other grating structures such as one-dimensional gratings. When the first out-coupling grating 210 and the second out-coupling grating 220 adopt one-dimensional gratings, the third out-coupling grating 230 adopts a two-dimensional grating, and the in-coupling grating 240 adopts a one-dimensional grating, the grating periods of the first out-coupling grating 210, the second out-coupling grating 220 and the in-coupling grating 240 are equal, and the grating period of the third out-coupling grating 230 along the arrangement direction of all the sub-out-coupling gratings of the third out-coupling grating 230 is twice the grating period of any one of the first out-coupling grating 210, the second out-coupling grating 220 and the in-coupling grating 240.

[0115] The optical structures 200 defined in the above embodiments of the present application can be applied to an optical device, and the optical device can include a projector and any of the above optical structures 200. The optical device can be an augmented reality device or a virtual reality device.

[0116] The optical structure and optical device provided in the embodiments of the present application are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for technicians in this field, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. An optical structure, characterized in that: include: Wave conductor; A first outcoupling grating, arranged on the waveguide; A second outcoupling grating, disposed on the waveguide; A third outcoupling grating, disposed on the waveguide body, wherein the third outcoupling grating is located between the first outcoupling grating and the second outcoupling grating; as well as An in-coupling grating is arranged on the same side of the first out-coupling grating, the second out-coupling grating and the third out-coupling grating, and the in-coupling grating and the third out-coupling grating are arranged side by side; Wherein, the third out-coupling grating includes at least two sub-out-coupling gratings, the junction of two adjacent sub-out-coupling gratings is located in the eye box of the optical structure, and the diffraction efficiency of the sub-out-coupling grating far away from the coupling-in grating is greater than the diffraction efficiency of the sub-out-coupling grating close to the coupling-in grating.

2. The optical structure according to claim 1, characterized in that: The grating depth of the out-coupling sub-grating far from the in-coupling sub-grating is greater than the grating depth of the out-coupling sub-grating close to the in-coupling sub-grating.

3. The optical structure according to claim 1, characterized in that: At least a portion of all sub-outcoupling gratings are located within the eye box.

4. The optical structure according to claim 3, characterized in that: The third outcoupling grating includes at least three sub-outcoupling gratings, wherein the at least three sub-outcoupling gratings include a first sub-outcoupling grating partially located on one side of the eye box, a second sub-outcoupling grating partially located on the other side of the eye box, and at least one sub-outcoupling grating completely located in the eye box; The length of the first out-coupling sub-grating along the arrangement direction of all out-coupling sub-gratings is greater than the sum of the lengths of at least one out-coupling sub-grating in the eye box along the arrangement direction of all out-coupling sub-gratings; The length of the second sub-outcoupling grating along the arrangement direction of all the sub-outcoupling gratings is greater than the sum of the lengths of at least one sub-outcoupling grating in the eye box along the arrangement direction of all the sub-outcoupling gratings.

5. The optical structure according to claim 4, characterized in that: There are one, two or three sub-outcoupling gratings completely located in the eye box, and the diffraction efficiencies of all sub-outcoupling gratings increase proportionally from a sub-outcoupling grating closest to the coupling-in grating to a sub-outcoupling grating farthest from the coupling-in grating.

6. The optical structure according to claim 4, characterized in that: The first out-coupling sub-grating and the second out-coupling sub-grating are symmetrically arranged relative to the out-coupling sub-grating completely located in the eye box.

7. The optical structure according to claim 4, characterized in that: The ratio of the length of the first sub-outcoupling grating or the second sub-outcoupling grating along the arrangement direction of all sub-outcoupling gratings to the length of all sub-outcoupling gratings is P1, and the ratio of the length of all sub-outcoupling gratings completely located in the eye box along the arrangement direction of all sub-outcoupling gratings to the length of all sub-outcoupling gratings is P2; Among them, P1 is greater than or equal to 30% and less than or equal to 45%, P2 is greater than or equal to 10% and less than 30%.

8. The optical structure according to any one of claims 1 to 7, characterized in that: The first out-coupling grating comprises at least two sub-out-coupling gratings, the number of the sub-out-coupling gratings of the first out-coupling grating is the same as the number of the sub-out-coupling gratings of the third out-coupling grating, and the junction of two adjacent sub-out-coupling gratings in the first out-coupling grating is located in the eye box of the optical structure, and the diffraction efficiency of the sub-out-coupling grating far from the in-coupling grating in the first out-coupling grating is greater than the diffraction efficiency of the sub-out-coupling grating close to the in-coupling grating; The second out-coupling grating includes at least two sub-out-coupling gratings, the number of the sub-out-coupling gratings of the second out-coupling grating is the same as the number of the sub-out-coupling gratings of the third out-coupling grating, and the junction of two adjacent sub-out-coupling gratings in the second out-coupling grating is located in the eye box of the optical structure, and the diffraction efficiency of the sub-out-coupling grating far away from the coupling-in grating in the second out-coupling grating is greater than the diffraction efficiency of the sub-out-coupling grating close to the coupling-in grating.

9. The optical structure according to any one of claims 1 to 7, characterized in that: The third out-coupling grating is a two-dimensional grating, the in-coupling grating is a one-dimensional grating, the grating period of the third out-coupling grating along the arrangement direction of all sub-out-coupling gratings of the third out-coupling grating is twice the grating period of the in-coupling grating, the first out-coupling grating and the second out-coupling grating are both one-dimensional gratings, or the first out-coupling grating and the second out-coupling grating are both two-dimensional gratings; The refractive index of any one of the first out-coupling grating, the second out-coupling grating, the third out-coupling grating and the in-coupling grating and the waveguide body is 1.5-3; When the first out-coupling grating and the second out-coupling grating are one-dimensional gratings, the periods of the first out-coupling grating, the second out-coupling grating and the in-coupling grating are equal; When the first outcoupling grating and the second outcoupling grating are two-dimensional gratings, the periods of the first outcoupling grating, the second outcoupling grating and the third outcoupling grating are equal.

10. An optical device, characterized in that: It includes: a projector configured to provide an augmented reality or virtual reality image; and An optical structure as claimed in any one of claims 1 to 9.

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