CN113495319A

CN113495319A - Optical structure and optical device

Info

Publication number: CN113495319A
Application number: CN202110871693.1A
Authority: CN
Inventors: 蒋楚豪
Original assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Current assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Priority date: 2021-07-30
Filing date: 2021-07-30
Publication date: 2021-10-12

Abstract

The embodiment of the application provides an optical structure and an optical device, wherein the optical structure comprises: a waveguide; the first light coupling grating is arranged on the waveguide body; a second outcoupling grating disposed on the waveguide; the third light coupling grating is arranged on the waveguide body and is positioned between the first light coupling grating and the second light coupling grating; the first coupling-out grating is a two-dimensional grating with a plurality of first grids, and the first grids are in an asymmetric shape, so that the light efficiency of the first coupling-out grating in the first direction is higher than that of the first coupling-out grating in the second direction; the first direction is a direction in which the first outcoupling grating faces the second outcoupling grating, and the first direction is opposite to the second direction. The embodiment of the application can improve the exit pupil uniformity of the edge field.

Description

Optical structure and optical device

Technical Field

The present application relates to the field of optical technology, and in particular, to an optical structure and an optical device.

Background

Optical devices such as Augmented Reality (AR) devices, Virtual Reality (VR) devices may display images through respective display devices. AR devices and/or VR device related technologies are increasingly used in various fields, such as military, medical, construction, education, engineering, movie, entertainment, and so on.

Among them, the AR glasses are one of the main implementations of the AR device, and its near-eye display system is to form a far virtual image by a series of optical imaging elements on a display device and project the far virtual image into human eyes. AR glasses products need to meet the set-through requirement, both to See the real outside world and to See virtual information, so the imaging system cannot be kept in front of the line of sight. For example, one or a group of optical combiners are added to integrate the virtual information and the real scene into a whole in a laminated mode.

In the related art, AR glasses have many optical implementation schemes such as catadioptric, reflective, one-dimensional Diffractive, Two-dimensional Diffractive, holographic optical, etc., wherein Two-dimensional Diffractive waveguiding (abbreviated as TDDW) is light and thin, has high penetration property of external light, has good color reproducibility, and has a large FOV, which is considered as the most promising optical scheme for consumer-grade AR glasses.

In the related art, the coupling grating of the TDDW architecture couples light from the optical projection engine into the waveguide, and the light coupled into the waveguide is totally internally reflected toward the coupling grating, and after reaching the coupling grating, the light is divided into expanded pupil light propagating to the left and expanded pupil light propagating to the right by diffraction. When the light acts with the coupling grating, a part of energy is coupled out to human eyes, so that a user can see the picture of the projection light machine. When the light rays of the marginal field of view are incident, the pupil-expanding light rays propagating on one side can enter human eyes, and the uniformity of the exit pupil of the marginal field of view is poor.

Disclosure of Invention

The embodiment of the application provides an optical structure and an optical device, which can improve the exit pupil uniformity of an edge field.

An embodiment of the present application provides an optical structure, which includes:

a waveguide;

the first light coupling grating is arranged on the waveguide body;

a second outcoupling grating disposed on the waveguide; and

the third coupling-out grating is arranged on the waveguide body and is positioned between the first coupling-out grating and the second coupling-out grating;

the first coupling-out grating is a two-dimensional grating with a plurality of first grids, and the first grids are in an asymmetric shape, so that the light efficiency of the first coupling-out grating in the first direction is higher than that of the first coupling-out grating in the second direction;

the first direction is a direction in which the first outcoupling grating faces the first outcoupling grating, and the first direction is opposite to the second direction.

An embodiment of the present application further provides an optical structure, which includes:

a waveguide;

the first light coupling grating is arranged on the waveguide body;

a second outcoupling grating disposed on the waveguide;

the third coupling-out grating is arranged on the waveguide body and is positioned between the first coupling-out grating and the second coupling-out grating; and

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;

the third outcoupling grating comprises at least two sub-outcoupling gratings, the junction of two adjacent sub-outcoupling gratings is located in the eye box of the optical structure, and the diffraction efficiency of the sub-outcoupling grating far away from the incoupling grating is greater than that of the sub-outcoupling grating close to the incoupling grating.

An embodiment of the present application further provides an optical device, which includes:

a projection light configured to provide an augmented reality or virtual reality image; and

an optical structure as claimed in any preceding claim.

The first light-coupling grating in the embodiment of the application is provided with a plurality of first grids, and each grid is in an asymmetric shape, so that the light efficiency of the first light-coupling grating in the first direction is higher than the light efficiency of the first light-coupling grating in the second direction. The energy of the wasted part of the light coupled out by the first coupling-out grating is smaller than that of other light, so that the exit pupil brightness and exit pupil uniformity of each field of view can be improved, and the difference between the energies of each field of view can be reduced.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings used in the description of the embodiments will be briefly introduced below. It is obvious that the drawings in the following description are only some embodiments of the application, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

For a more complete understanding of the present application and its advantages, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, wherein like reference numerals represent like parts in the following description.

Fig. 1 is a schematic structural diagram of an optical structure provided in an embodiment of the present application.

Fig. 2 is a perspective view of an optical structure provided in an embodiment of the present application.

Fig. 3 is a schematic diagram of transmission of central field rays in an optical structure according to an embodiment of the present disclosure.

Fig. 4 is a schematic diagram of transmission of light rays in an optical structure in an edge field of view according to an embodiment of the present disclosure.

Fig. 5 is a schematic diagram of a light transmission process of an optical structure in k-space according to an embodiment of the present application.

FIG. 6 is a schematic diagram of a plane transmission of central field rays in an optical structure according to an embodiment of the present application.

FIG. 7 is a schematic diagram of the edge field light propagating along a plane in an optical structure according to an embodiment of the present disclosure.

Fig. 8 is a schematic view of an application scenario of the optical structure according to the embodiment of the present application.

Fig. 9 is a grating vector diagram of a first coupled-out grating according to an embodiment of the present disclosure.

Fig. 10 is a schematic view of an optical structure and a partial structure of a first outcoupling grating in the optical structure according to the embodiment of the present application.

Fig. 11 is a schematic partial structure diagram of a first outcoupling grating in an optical structure according to an embodiment of the present application.

Fig. 12 is a schematic partial structure diagram of a first outcoupling grating in an optical structure according to an embodiment of the present application.

Fig. 13 is a schematic partial structure diagram of a first outcoupling grating in an optical structure according to an embodiment of the present application.

Fig. 14 is a schematic partial structure diagram of a first outcoupling grating in an optical structure according to an embodiment of the present application.

Fig. 15 is a schematic partial structure diagram of a first outcoupling grating in an optical structure according to an embodiment of the present application.

Fig. 16 is a schematic diagram of an optical structure provided in an embodiment of the present application.

Fig. 17 is a schematic diagram of an optical structure provided in an embodiment of the present application.

Fig. 18 is a schematic diagram of an optical structure provided in an embodiment of the present application.

Fig. 19 is a schematic diagram of an optical structure provided in an embodiment of the present application.

Fig. 20 is a schematic diagram of an optical structure provided in an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without inventive step, are within the scope of the present application.

Referring to fig. 1, fig. 1 is a schematic structural diagram of an optical structure according to an embodiment of the present disclosure, and shows a reference frame (x, y, z). The optical structure 200 includes a waveguide 250, an incoupling grating 240 disposed on the waveguide, and a plurality of outcoupling gratings (outcoupling gratings 210, outcoupling gratings 220, and outcoupling gratings 230). The waveguide 260, the incoupling grating 240, and the outcoupling gratings (the outcoupling grating 210, the outcoupling grating 220, and the outcoupling grating 230) of the optical structure 200 are all arranged in the x-y plane.

Wherein the waveguide 250 serves as a carrier for the optical structure 200. The waveguide 250 is capable of conducting an optical signal, such as by total internal reflection. The waveguide 250 may have two oppositely disposed surfaces, such as including a first surface 252 and a second surface that are oppositely disposed. Wherein the second surface is disposed opposite the first surface 252 and is obscured from view in fig. 1 and not shown.

In which an incoupling grating 240 is provided at one of the surfaces of a waveguide 250, such as a first surface 252. The incoupling grating 240 can receive an optical signal (also referred to as light) from a projection optical engine (not shown) and couple the optical signal into the waveguide 250. The waveguide 250 may conduct the optical signal after receiving the optical signal coupled in from the incoupling grating 240.

The incoupling grating 240 may be any one of a blazed grating, a rectangular grating, and a slanted grating. Incoupling grating 240 may employ a one-dimensional grating.

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 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 face of the waveguide 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 side of the waveguide body 250, i.e., on a second surface opposite to the first surface.

In 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 of the faces 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 face 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 scope of the embodiments of the present application.

The incoupling grating 240 in the present embodiment may be disposed on the same side of the first outcoupling grating 210, the second outcoupling grating 220 and the third outcoupling grating 230, and the incoupling grating 240 and the third outcoupling grating 230 are arranged side by side. In the embodiment of the present application, the first outcoupling grating 210 and the second outcoupling grating 220 have the same shape, and the first outcoupling grating 210 and the second outcoupling grating 220 are symmetrically arranged with respect to the third outcoupling grating 230, which can also be understood as that the first outcoupling grating 210 and the second outcoupling grating 220 are arranged in a mirror image with respect to the third outcoupling grating 230. It should be noted that the first outcoupling grating 210 and the second outcoupling grating 220 may also have different shapes or may not be symmetrically arranged with respect to the third outcoupling grating 230.

The waveguide 250 may propagate the optical signal coupled in by the coupling-in grating 240 toward the first coupling-out grating 210, the second coupling-out grating 220, and the third coupling-out grating 230 through total internal reflection, and after reaching the first coupling-out grating 210, the second coupling-out grating 220, and the third coupling-out grating 230, the optical signal may be divided into several parts by diffraction and be transmitted toward multiple directions. Wherein, a part of the optical signals are coupled out to reach human eyes, so that a user can see the picture of the projection light machine.

Referring to fig. 2, fig. 2 is a perspective view of an optical structure according to an embodiment of the present disclosure, and fig. 2 shows a transmission of an optical signal after diffraction of light incident on a central field of view, and shows a reference frame (x, y, z). After the central field of view light is incident on the incoupling grating 240, the incoupling grating 240 transmits the light 201 through the waveguide 250 towards the third outcoupling grating 230. The light 201 is diffracted into 4 beams of light, which are the light 2011, the light 2012, the light 2013 and the light 2014 after the light interacts with the third coupling-out grating 230.

Ray 2011 follows the path of ray 201. It is understood that the light 201 is diffracted and split into 4 beams by the third outcoupling grating 230, and the light 2011 is diffracted and split into 4 beams by the third outcoupling grating 230 multiple times during the process of proceeding along the light 201. That is, the light ray 2011 acts on the third outcoupling grating 230 for many times during the process of advancing along the original path of the light ray 201, and is diffracted to split the

light rays

2013, 2014 and 2011, and the plurality of 2011 are all advanced along the original path of the light ray 201 to form one light ray. The light 2011, after reacting with the third outcoupling grating 230 once, decreases its energy.

The light 2012 is directly coupled out from the third coupling-out grating 230, and it can be understood that the light 2012 is coupled out toward the positive direction z based on the x-y plane. The embodiment of the present application defines all the light directly coupled out from the third coupling-out grating 230 as light 2012. It will be appreciated that the energy of different light rays directly coupled out from different positions of the third outcoupling grating 230 is different.

The light ray 2013 is split into 2 rays, a light ray 2013A and a light ray 2013B, by diffraction after interacting with the first outcoupling grating 210. Light ray 2013A is coupled directly out of first outcoupling grating 210, which can be understood as light ray 2013A being coupled out in the positive direction of z based on the x-y plane. Ray 2013B follows the original path of ray 2013. In the embodiment of the present application, the light ray propagating from the third outcoupling grating 230 toward the first outcoupling grating 210 is defined as a light ray 2013, the light ray 2013 has a plurality of light rays 2013, and each light ray 2013 is separated into a plurality of light rays 2013A and a plurality of light rays 2013B by diffraction after acting on the first outcoupling grating 210. It will be appreciated that the energy of the different rays 2013 will be different, the energy of the different rays 2013A will be different, and the energy of the different rays 2013B will be different.

The light 2014 is diffracted into 2 light beams, namely, light 2014A and light 2014B, after the light beam 2014 interacts with the second coupling-out grating 220, and the light beam 2014A is directly coupled out from the second coupling-out grating 210, which can be understood as light 2014A being coupled out in the positive direction of z based on the x-y plane. Light 2014B follows the original path of light 2014. In the embodiment of the present application, the light ray propagating from the third outcoupling grating 230 toward the second outcoupling grating 220 is defined as a light ray 2014, and each of the light rays 2014 is split into a plurality of light rays 2014A and a plurality of light rays 2014B by diffraction after the light rays 2014 and the second outcoupling grating 220 act on each other. It is understood that the energy of different light rays 2014 is different, the energy of different light rays 2014A is different, and the energy of different light rays 2014B is different.

The light rays coupled out based on the x-y plane towards the positive direction of z can be incident into human eyes, so that a user can see the picture of the projection light machine. Referring to fig. 2, in the example shown in fig. 2, the light 2012 coupled out from the third coupling-out grating 230 toward the positive direction z enters the human eye, the light 2013A coupled out from the first coupling-out grating 210 toward the positive direction z enters the human eye, and the light 2014A coupled out from the second coupling-out grating 220 toward the positive direction z enters the human eye.

It should be noted that the

light rays

2011, 2012, 2013 and 2014 shown in fig. 2 are exemplary and do not limit the number of light rays coupled out from the optical structure 200. Or it can be understood that fig. 2 shows a part of the light rays when the optical structure 200 of the embodiment of the present application is coupled out, and the rest of the light rays are not shown.

Referring to fig. 3 and 4, fig. 3 is a schematic diagram illustrating transmission of a central field of view ray in an optical structure according to an embodiment of the present disclosure, and fig. 4 is a schematic diagram illustrating transmission of an edge field of view ray in an optical structure according to an embodiment of the present disclosure. The coupled-in grating 240 transmits the coupled-out light 201 to the third coupled-out grating 230 through the waveguide 250, and the coupled-out grating 230 and the third coupled-out grating act to split a plurality of light rays such as light ray 2011, light ray 2012, light ray 2013 and light ray 2014, wherein the transmission directions of the light ray 2011, the light ray 2012, the light ray 2013 and the light ray 2014 can refer to fig. 2 and related contents, which are not described herein again. Note that the light rays 2012 are replaced by dots in the x-y plane. The light ray 2013 and the first coupling grating 210 are acted to split a plurality of light rays such as a light ray 2013A and a light ray 2013B, and the light ray 2013A and the light ray 2013B can refer to fig. 2 and related contents, which are not described herein again. Note that the light ray 2013A is replaced by a circular dot in the x-y plane. The light 2014 and the second coupling-out grating 220 are separated into a plurality of light beams such as the light beam 2014A and the light beam 2014B, and the light beam 2014A and the light beam 2014B can refer to fig. 2 and related contents, which are not described herein again. Note that ray 2014A is replaced by a dot in the x-y plane. As schematically shown in fig. 3 and 4, each dot represents a light ray that interacts with a outcoupling grating, and the light rays represented by the dots may be incident on the human eye.

Fig. 3 and 4 show that each outcoupling grating can couple out a plurality of light rays in the positive direction of the z-axis.

It should be noted that only a part of the light rays represented by the dots in fig. 3 and 4 is incident on the human eye.

Referring to fig. 5, fig. 5 is a schematic diagram of the optical structure in k-space during the light transmission process according to the embodiment of the present application, and shows a reference system (kx, ky, kz). The two radii shown in fig. 5 are the ambient refractive index and the waveguide refractive index, respectively, where the radius of the small circle, i.e., the radius of the circle located at the inner circle, is the ambient refractive index, and the radius of the large circle, i.e., the radius of the outer circle, is the waveguide refractive index. The rectangles represent the field of view (FOV), each rectangle represents a field of view, and the rectangles at different positions represent different states of the light rays in the field of view, for example, the central rectangle of the circle represents the light rays (light rays 2012, light rays 2013A, and light rays 2014A) entering or exiting the waveguide 250 from the projection light device in the field of view, and the rectangle in the circle (i.e., between the two circles) represents the light rays in the field of view propagating in the waveguide 240 after being coupled by the gratings (the first coupling-out grating 210, the second coupling-out grating 220, and the coupling-in grating 240). A field of view within a small circle means that light can be coupled out of the waveguide 250, a field of view within a circle means that light propagates within the waveguide 250, and a field of view outside a large circle means that light is not actually present. The diffracted k1 is coupled into the entrance waveguide 250 through the in-coupling grating 240 at the origin of coordinates, and then the light ray 201 changes to 6 different positions around its k-space through the 6 diffracted components k22 of the third out-coupling grating 230, where the light ray 2013 and the light ray 2014 are also in a circle, representing that they will be totally internally reflected to the left and right along the kx axis, respectively, to become expanded pupil light rays. A further portion of the light will be diffracted and shifted upwards to coincide with the original incident image, indicating that they (such as light 2012) will be coupled out directly. The remaining 3 positions are all outside the circle, indicating that these 3 diffraction components do not exist. Not all of the energy of the light ray 201 is diffracted, but most of the energy remains unchanged, which means that most of the energy continues to be totally internally reflected along the propagation direction of the light ray 201.

The region where the optical structure 200 is coupled out and incident to the human eye is defined as an eye box (Eyebox)260 in the embodiment of the present application. I.e., light rays that are within the eye box260 and coupled out in the positive z-axis direction are incident on the human eye.

The eye box will be explained below.

Referring to fig. 6 to 8, fig. 6 is a schematic view illustrating transmission of a central field of view light in an optical structure along a plane according to an embodiment of the present disclosure, fig. 7 is a schematic view illustrating transmission of an edge field of view light in an optical structure along a plane according to an embodiment of the present disclosure, and fig. 8 is a schematic view illustrating an application scenario of an optical structure according to an embodiment of the present disclosure. Assuming that the incident field of view is in the y-z plane at an angle ranging from-a ° to a ° from the z-axis, i.e., the maximum incident field of view F2 is in the y-z plane at an angle ranging from a ° to the z-axis, and the minimum incident field of view F1 is in the y-z plane at an angle ranging from-a °. The distance (eyerelief) from the human eye to the waveguide 250 is b, i.e., the distance b from the Eyebox plane or the human eye viewing plane to the waveguide 250. The length of the eye box260 in the y-axis direction is B, where B-a-2B tan (a).

Where 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 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 in the embodiment of the present application.

In an alternative embodiment of the present application, the center of the eye box260 may coincide with the center of the third outcoupling grating 230.

Referring to fig. 2, fig. 3 and fig. 6, when the light of the central field of view is incident on the optical structure 200, a portion of the light coupled out by the first coupling-out grating 210, the second coupling-out grating 220 and the third coupling-out grating 230, such as the light 2012, the light 2013A and the light 2014A, is within the eye box260 and then enters the human eye.

Referring to fig. 4 and fig. 7, when the light in the fringe field of view is incident on the optical structure 200, only a portion of the

light rays

2012 and 2014A coupled out by the second coupling-out grating 220 and the third coupling-out grating 230 are within the eye box260, and substantially all of the light rays such as the light ray 2013A coupled out by the first coupling-out grating 210 are not within the eye box 260. In other words, the energy of the light coupled out by the second coupling-out grating 220 and the third coupling-out grating 230 is utilized, and the energy of the light coupled out by the first coupling-out grating 210 is wasted, which often results in poor exit pupil uniformity of the fringe field.

Moreover, in the waveguide architecture in the related art, the exit pupil uniformity of the edge field is significantly worse than that of the central field, which means that when the projector is viewed at some Eyebox positions, the difference between the brightness of the central field and that of the edge field is relatively large, which causes discomfort for the user.

The first outcoupling grating 210 defined based on this 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 propagating in the first direction of the first outcoupling grating 210 is higher than the efficiency of light propagating in the second direction of the first outcoupling grating 210. The energy of the wasted part of the light coupled out by the first coupling grating 210 is smaller than that of other light, so that the exit pupil brightness and exit pupil uniformity of each field of view can be improved, and the difference between the energies of each field of view can be reduced. Such as improving exit pupil brightness and exit pupil uniformity for marginal fields of view, and reducing the difference between marginal field of view energy and central field of view energy. Especially, when the optical structure 200 is applied to a head-mounted display product such as an AR, the rainbow effect of suppressing sunlight can be improved, and the image quality of the product can be improved.

Wherein the first direction is a direction in which the first outcoupling grating 210 faces the second outcoupling grating 220, such as the negative direction of the x-axis shown in fig. 1. The second direction is the direction of the second outcoupling grating 220 towards the first outcoupling grating 210, such as the positive direction of the x-axis shown in fig. 1. The first direction and the second direction are opposite in the embodiment of the application.

Referring to fig. 9, fig. 9 is a diagram illustrating grating vectors of a first coupled-out grating according to an embodiment of the present disclosure. The first outcoupling grating 210 has a multi-order diffraction vector including (1,1), (1,0), (0,1), (0, -1), (-1,0), (-1, -1). The diffraction efficiencies of the (1,0) and (-1,0) orders in the diffraction orders of the first outcoupling grating 210 are significantly higher than those of the (0,1) and (0, -1) orders, and when the light 201 is incident on the first outcoupling grating 210, the light 2014B is generated by the diffraction of the (-1,0) order of the first outcoupling grating 210, and the light 2013B is generated by the diffraction of the (0,1) order of the first outcoupling grating 210, so that the light 2014B propagating to the left (first direction) in the drawing has a much higher efficiency than the light 2013B propagating to the right (second direction) in the drawing.

For the purpose of describing the asymmetric shape of the first grid 212 in this embodiment of the present application, the light efficiency of the first outcoupling grating 210 in the first direction is higher than the light efficiency of the first outcoupling grating 210 in the second direction. This is described below in connection with a schematic view of the first outcoupling grating 210.

Referring to fig. 10 to 13, fig. 10 is a schematic view of an optical structure and a partial structure of a first light-coupling grating in the optical structure according to the embodiment of the present application, fig. 11 is a schematic view of a partial structure of a first light-coupling grating in the optical structure according to the embodiment of the present application, fig. 12 is a schematic view of a partial structure of a first light-coupling grating in the optical structure according to the embodiment of the present application, and fig. 13 is a schematic view of a partial structure of a first light-coupling grating in the optical structure according to the embodiment of the present application. Wherein the partial structure M of the first outcoupling grating 210 shown in fig. 10 is defined as a first portion M. I.e. the plurality of first grids 212 in the first portion M are part of the first grids 212 of the first outcoupling grating 210.

All first grids 212 of the plurality of first grids 212 of the first outcoupling grating 210 may have substantially the same shape. For example, each first grid 212 has four vertices such as vertex c, vertex d, vertex e, and vertex f, which may form a first diagonal ce and a second diagonal df. The length of the first diagonal ce is greater than the length of the second diagonal df, an included angle θ acx between the first diagonal ac and the third out-coupling grating 230 in the third direction is an acute angle, and an included angle θ acy between the second diagonal bd and the third out-coupling grating in the third direction is an obtuse angle.

Wherein the third direction is a direction from the third outcoupling grating 230 to the incoupling grating 240.

In an alternative embodiment of the present application, the first grids 212 of the same shape are arranged in a hexagonal lattice periodicity in the x-y plane, having two periodic directions, a and b, respectively, with an angle of 30 ° between the periodic directions. Wherein the period direction a is parallel to the y-axis, the distance between two first grids 212 along the period direction a is Pa, the period direction b forms an angle of 30 ° with the y-axis, and the distance between two first grids 212 along the period direction b is Pb. Pa may be 0.4 μm to 3 μm, and Pb may be 0.2 μm to 2 μm. Pa and Pb need to satisfy the relation: Pa-Pb/2 cos (30 °).

The asymmetric shape of the first grids 212 in the embodiment of the present application may also be understood as that the first grids 212 are asymmetric shapes of the first grids 212 about both the x axis and the y axis, the first diagonal line ce of the first grids 212 is always longer than the second diagonal line df, and an included angle θ acy between the first diagonal line ce and the positive direction of the y axis is an obtuse angle, and an included angle θ acx between the first diagonal line ce and the positive direction of the x axis is an acute angle.

The first outcoupling grating 210 has a plurality of sets of grating groups 211, each set of grating groups 211 comprises a plurality of first gratings 212, and each first grating 212 in each set of grating groups 211 intersects with its neighboring first grating 212, and each set of grating groups 211 is spaced apart from each other. In an alternative embodiment of the present application, the sets of grid sets 211 are parallel to each other. The first grids in each grid set 211 are arranged in the sixth direction. It is also understood that each first grid 212 intersects the next first grid 212 adjacent in an oblique direction, both top right and bottom left.

The sixth direction is a seventh direction rotated by 30 degrees clockwise, wherein the seventh direction is a direction of the third outcoupling grating 230 toward the incoupling grating 240. The seventh direction may be a positive direction of Pa, that is, the sixth direction is Pb 1.

It should be noted that the number of vertices of the first grid 211 is not limited to four, such as the first grid includes at least five vertices, i.e., the first grid 211 may have 5 or more vertices. The present embodiment will be described with reference to 5 vertices.

Referring to fig. 14, fig. 14 is a schematic partial structure view of a first outcoupling grating in an optical structure according to an embodiment of the present application. The vertices of the first grid 212 include two vertices (vertex c and vertex d) close to the third outcoupling grating 230 and two vertices (vertex e and vertex f) far from the third outcoupling grating 230, the two vertices (vertex c and vertex d) close to the third outcoupling grating 230 and the two vertices (vertex e and vertex f) far from the third outcoupling 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 that of the fourth diagonal line df, the angle between the third diagonal line ce and the third outcoupling grating 230 in the fourth direction is an acute angle, and the angle between the fourth diagonal line df and the third outcoupling grating 230 in the fourth direction is an obtuse angle.

Wherein the fourth direction is a direction from the third outcoupling grating 230 to the incoupling grating 240. I.e. the fourth direction may be understood as the third direction. The third diagonal line ce and the fourth diagonal line df may refer to the third diagonal line ce and the fourth diagonal line df shown in fig. 11 to 13, which are not described herein again. The first grid 212 and the grid set 211 can refer to the first grid 212 and the grid set 211 shown in fig. 11 to 13, which are not described herein again.

It should be noted that the number of vertices of the first grid 211 is not limited to four, five, or more than five, such as the first grid includes three vertices, i.e., the first grid 211 may have three vertices.

Referring to fig. 15, fig. 15 is a schematic partial structure view of a first outcoupling grating in an optical structure according to an embodiment of the present application. The vertexes of the first grid 212 include a vertex c, a vertex d, and a 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 outcoupling grating 230, the second vertex connecting edge de is far away from the third outcoupling grating 230, the length of the first vertex connecting edge cd is greater than that of the second vertex connecting edge de, an included angle between the first vertex connecting edge cd and the third outcoupling grating 230 in the fifth direction is an acute angle, and an included angle between the second vertex connecting edge de and the third outcoupling grating 230 in the fifth direction is an obtuse angle

Wherein the fifth direction is a direction from the third outcoupling grating 230 to the incoupling grating 240. I.e. the fifth direction may be understood as the third direction. The first vertex connecting edge cd and the second vertex connecting edge de may refer to the third diagonal line ce and the fourth diagonal line df shown in fig. 11 to 13, which is not described herein again. The first grid 212 and the grid set 211 can refer to the first grid 212 and the grid set 211 shown in fig. 11 to 13, which are not described herein again.

In the embodiment of the present application, the first outcoupling grating 210 and the second outcoupling grating 220 have the same shape, and the first outcoupling grating 210 and the second outcoupling grating 220 are symmetrically arranged with respect to the third outcoupling grating 230, which can also be understood as that the first outcoupling grating 210 and the second outcoupling grating 220 are arranged in a mirror image with respect to the third outcoupling grating 230. That is, the grids in the second out-coupling grating 220 are two-dimensional gratings, and the grid structure of each two-dimensional grating has the same shape and arrangement as the first grid 212. Such as the second outcoupling grating 220 being a two-dimensional grating having a plurality of second grids, all of the second grids of the second outcoupling grating 220 are the same shape and the same arrangement as all of the first grids of the first outcoupling grating 210. Specific shapes and arrangement manners can be seen in fig. 11 to 15, which are not described herein again.

Wherein the third out-coupling grating 230 is a two-dimensional grating having a plurality of third grids, and the third grids are symmetrical shapes, such as two-dimensional gratings with left-right symmetrical shapes, so that the efficiency of the light propagating to the left is opposite to that of the light propagating to the right, which is beneficial to the size of the eye box260 with enlarged edge field angle. The third grid may be arranged in a hexagonal lattice and the grating vector may be as shown in figure 9, with the (1,1) order diffraction vector parallel to the y-axis. The third grid may be any shape that is symmetrical along the y-axis, such as circular, square, diamond, hexagonal, octagonal, etc. The area of the third outcoupling grating 230 may be rectangular, for example, the lateral width in the x-axis direction may be 1mm to 15mm, and the longitudinal width in the y-axis direction may be 20mm to 35 mm.

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

The coupling-in grating 240, the first coupling-out grating 210, the second coupling-out grating 220 and the third coupling-out grating 230 may be made of silicon, plastic, glass, polymer or some combination thereof.

As shown in fig. 2, the display brightness at each position in the Eyebox260 is determined by the intensity of the outcoupled light at the position, so the intensities of the light 2012, the light 2013A and the light 2014A directly determine the display quality of the Eyebox 260. In practical applications, the intensity of the light ray 2012 is much weaker than the light ray 2013A and the light ray 2014A, which causes the position of the Eyebox260 corresponding to the light ray 2012 to present a dark area, which greatly affects the use experience of the consumer. The reason why the intensity of the light 2012 is weaker than that of the light 2013A and the light 2014A is that the outcoupling efficiency of the third outcoupling grating 230 cannot be set too high, otherwise the main light 201 is attenuated too fast in the propagation process, and the too fast attenuated light 201 causes the light intensity difference between the light 2012, and finally causes the more serious uneven brightness of the Eyebox 260.

Based on this, the embodiment of the present application provides an optical structure to improve the efficiency of the third outcoupling grating 230 without the intensity difference between the light beams 2012, such as the optical structure 200 of the embodiment of the present application divides the third outcoupling grating 230 into a plurality of regions along the y-axis, and the efficiency between the different regions along the y-axis gradually increases, so that although the main light beam 201 attenuates during the propagation process, the efficiency of the corresponding outcoupling grating of 2012 and even more subsequent outcoupling gratings can be gradually increased, and thus although the main light beam 201 accelerates the attenuation due to the improvement of the efficiency of the third outcoupling grating 230, the energy difference between the light beams 2012 and even more subsequent outcoupling beams can be decreased, so that the energy of the light beam 2012 is closer to the light beam 2013A and the light beam 2014A while the intensity difference between the light beams 2012 is decreased, and finally the luminance and the uniformity of the Eyebox260 are simultaneously increased, eyebox260 is greatly improved in both energy and brightness uniformity. In summary, the embodiment of the present application introduces a technique of dividing the third outcoupling grating 230 into a plurality of gratings, so as to solve the above problems, and greatly improve the energy and brightness uniformity of the Eyebox260, so that the embodiment of the present application has a great implementation significance, and is a diffraction waveguide architecture with excellent performance.

In the embodiment of the present application, the third out-coupling grating 230 includes at least two sub out-coupling gratings, a junction of two adjacent sub out-coupling gratings is located in the eye box260 of the optical structure 200, and the diffraction efficiency of the sub out-coupling grating far away from the in-coupling grating 240 is greater than the diffraction efficiency of the sub out-coupling grating close to the in-coupling grating 240. So that the total energy of the light coupled out by the third out-coupling grating 230 is substantially the same, or it is understood that the energy of the light coupled out by each sub-out-coupling grating of the third out-coupling grating 230 is substantially the same. And the intensity of the light coupled out by the third light-coupling grating 230 is not affected. The following is a detailed description with reference to the drawings.

In an optional implementation manner of the embodiment of the present application, a grating depth of the sub-outcoupling grating far away from the incoupling grating 240 is greater than a grating depth of the sub-outcoupling grating near the incoupling grating 240, so that a diffraction efficiency of the sub-outcoupling grating far away from the incoupling grating 240 is greater than a diffraction efficiency of the sub-outcoupling grating near the incoupling grating 240. That is, an alternative embodiment of the present application defines an optical structure 200 with a deeper grating, a higher diffraction efficiency.

Referring to fig. 16 and 17, fig. 16 is a schematic view of an optical structure provided in an embodiment of the present application, and fig. 17 is a schematic view of the optical structure provided in the embodiment of the present application. The third outcoupling grating 230 of the optical structure 200 may include three sub-outcoupling gratings, at least a portion of each of which is located within the eye box 260. Such as the third outcoupling grating 230, comprises a part of the first sub-outcoupling grating 231 located at one side of the eye box260, a part of the second sub-outcoupling grating 232 located at the other side of the eye box260, and the third sub-outcoupling grating 2323 located completely inside the eye box 260.

The length of the first sub-outcoupling grating 231 along the arrangement direction of all the sub-outcoupling gratings is greater than the length of the third sub-outcoupling grating 233 along the arrangement direction of all the sub-outcoupling gratings in the eye box 260. Or that the length of the first sub-outcoupling grating 231 in the y-axis direction is greater than the length of the third sub-outcoupling grating 233 in the y-axis direction in the eye box 260.

The length of the second sub-outcoupling grating 232 along the arrangement direction of all the sub-outcoupling gratings is greater than the length of the third sub-outcoupling grating 233 along the arrangement direction of all the sub-outcoupling gratings in the eye box 260. Or that the length of the second sub-outcoupling grating 232 in the y-axis direction is larger than the length of the third sub-outcoupling grating 233 in the y-axis direction inside the eye box 260.

In an alternative embodiment 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 equal to 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 with respect 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 not be equal.

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 alternative embodiment of the present application, a ratio of a length of the first sub-outcoupling grating 231 along the arrangement direction of all the sub-outcoupling gratings to a length of the arrangement direction of all the sub-outcoupling gratings is P1, that is, a ratio of a length of the first sub-outcoupling grating 231 along the y-axis direction to a 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 in the arrangement direction of all the sub-outcoupling gratings to the length of the arrangement direction of all the sub-outcoupling gratings is P2, i.e. the ratio of the length of the third sub-outcoupling grating 233 in the y-axis direction to the length of the third outcoupling grating 230 in the y-axis direction is P2. P1 is greater than or equal to 30% and P1 is less than or equal to 45%, P2 is greater than or equal to 10% and P2 is less than 30%.

In an alternative embodiment of the present application, the portion of the first sub-outcoupling grating 231 located in the eye box260 has the same size as the portion of the second sub-outcoupling grating 232 located in the eye box 260. With reference to fig. 5 and 6, the boundaries of the sub-outcoupling gratings of the third outcoupling grating 230 are located within a range of B/2 above and below the center of the third outcoupling grating 230.

In an alternative embodiment of the present application, the diffraction efficiency of all the sub-outcoupling gratings increases proportionally from the one sub-outcoupling grating closest to the incoupling grating 240, such as the first sub-outcoupling grating 231, to the one sub-outcoupling grating farthest from the incoupling grating 240, such as the second sub-outcoupling grating 232. It is also understood that the diffraction efficiency of all sub-out-coupling gratings increases in equal proportion in the positive y-axis direction. For example, the diffraction efficiency of the third sub-outcoupling grating 233 is n times higher than that of the first sub-outcoupling grating 231, n being greater than 1. The diffraction efficiency of the second sub-outcoupling grating 232 is n times that of the third sub-outcoupling grating 233. Therefore, the energy difference of the light rays coupled out by each sub-diffraction grating can be ensured to be not large.

It should be noted that the division of the third outcoupling grating 230 into three regions shown in fig. 16 and 17 is only exemplary, and does not limit the number of the regions of the third outcoupling grating 230. For example, the third outcoupling grating 230 may comprise two sub-outcoupling gratings, four sub-outcoupling gratings, five sub-outcoupling gratings, or the like. The greater number of sub-outcoupling gratings will not be described one by one here.

It should be noted that, when the number of the sub-out-gratings of the third out-coupling grating 230 is greater than three, such as four or five, it still satisfies that the boundary of two adjacent sub-out-gratings among all the sub-out-coupling gratings of the third out-coupling grating 230 are located in the eye box260 of the optical structure 200, and the diffraction efficiency of the sub-out-grating far from the in-grating 240 is greater than that of the sub-out-grating near to the in-grating 240. It is also possible to make the total energy of the light coupled out by the third outcoupling grating 230 substantially the same, or to understand that the energy of the light coupled out by each sub-outcoupling grating of the third outcoupling grating 230 is substantially the same. And the intensity of the light coupled out by the third light-coupling grating 230 is not affected.

When the number of sub-out-gratings of the third out-grating 230 is larger than three, such as four, five. At least a portion of all the sub-gratings of the third out-coupling grating 230 may be located within the eye box 260. That is, the third outcoupling grating 230 includes one outcoupling grating partially located on one side of the eye box260, one sub-outcoupling grating partially located on the other side of the eye box260, and two or more sub-outcoupling gratings completely located in the eye box 260. The sum of the lengths of all the sub-outcoupling gratings completely located in the eye box260 along the arrangement direction of all the sub-outcoupling gratings of the third outcoupling grating 230 is less than the length of any one of the sub-outcoupling gratings partially located outside the eye box260 along the arrangement direction of all the sub-outcoupling gratings of the third outcoupling grating 230. It is also understood that the sum of the lengths of all the sub-outcoupling gratings completely located inside the eye box260 in the y-axis direction is smaller than the length of any one of the sub-outcoupling gratings partially located outside the eye box260 in the y-axis direction.

Compared to fig. 16 and 17, the ratio of the sum of the lengths of the at least two sub-outcoupling gratings, the third outcoupling grating 230 being located completely within the eye box260, in the y-axis direction to the length of the third outcoupling grating 230 in the y-axis direction is P2. The remaining features can be seen in fig. 16 and 17, which are not described in detail herein.

Referring to fig. 18, fig. 18 is a schematic view of an optical structure according to an embodiment of the present disclosure. Fig. 18 shows that the third outcoupling grating 230 includes 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 contents and are not described herein again. The third sub-outcoupling grating 233 and the fourth sub-outcoupling grating are both located within the eye box 260.

Referring to fig. 19, fig. 19 is a schematic view of an optical structure according to an embodiment of the present disclosure. Fig. 19 shows that the third outcoupling grating 230 includes five sub-outcoupling gratings, namely a first sub-outcoupling grating 231, a second sub-outcoupling grating 232, a third sub-outcoupling grating 233, a fourth sub-outcoupling grating 234 and a fifth sub-outcoupling grating 235, wherein the first sub-outcoupling grating 231 and the second sub-outcoupling grating 232 can refer to the above contents and are not described herein again. The third sub-outcoupling grating 233, the fourth sub-outcoupling grating, and the fifth sub-outcoupling grating are located in the eye box 260.

Considering that the intensities of the

light rays

2012, 2013A and 2014A directly determine the display quality of the Eyebox260, the intensity of the light ray 2012 is much weaker than the intensities of the light rays 2013A and 2014A in practical applications. In some embodiments of the present application, the third outcoupling grating 230 capable of outcoupling the light 2012 is disposed in different regions, so that the energy of the light 2012 is closer to the light 2013A and the light 2014A, and the intensity difference between the light 2012 is reduced, and finally the luminance and the luminance uniformity of the Eyebox260 are improved at the same time, and the energy and the luminance uniformity of the Eyebox260 are both greatly improved. In practice, light 2013A and light 2014A lose energy as they propagate. In order to further improve the brightness and the brightness uniformity of the Eyebox 260. In some alternative embodiments of the present application, the first outcoupling grating 210 and the second outcoupling grating 220 are also arranged in different regions. The following is a detailed description with reference to the drawings.

Referring to fig. 20, fig. 20 is a schematic view of an optical structure according to an embodiment of the present disclosure. The first outcoupling grating 210, the second outcoupling grating 220 and the third outcoupling grating 230 in the optical structure 200 shown in fig. 20 are arranged in regions. The arrangement of the sub-regions of the third out-coupling grating 230 can be seen in fig. 16 to 19, and is not described herein again.

Wherein the first out-coupling grating 210 comprises 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 all three. And the intersection of two adjacent sub-outcoupling gratings in the first outcoupling grating 210 is located in the eye box260 of the optical structure 200. The diffraction efficiency of the sub-outcoupling gratings of the first outcoupling grating 210 that are distant from the incoupling grating 240 is larger than the diffraction efficiency of the sub-outcoupling gratings that are close to the incoupling grating 240. So that the total energy of the light coupled out by the first out-coupling grating 210 is substantially the same, or the energy of the light coupled out by each sub-out-coupling grating of the first out-coupling grating 210 is substantially the same. And the intensity of the light coupled out by the first coupling-out grating 210 is not affected.

The sub-outcoupling gratings of the first outcoupling grating 210 shown in fig. 20 are illustrated by way of example in three. 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 may refer to the first sub-outcoupling grating 231, the second sub-outcoupling grating 212 may refer to the third sub-outcoupling grating 233, and the third sub-outcoupling grating 213 may refer to the second sub-outcoupling grating 232, which will not be described herein again. It should be noted that, when the number of the sub-regions of the first outcoupling grating 210 and the number of the sub-regions of the third outcoupling grating 230 are both greater than three, referring to fig. 18 and 19, 2 sub-outcoupling gratings, 3 sub-outcoupling gratings, or more sub-outcoupling gratings are arranged between the first sub-outcoupling grating 211 and the third sub-outcoupling grating 213, and the arrangement manner of the sub-outcoupling gratings is the same as that of the sub-outcoupling gratings of the third outcoupling grating 230, which is not described herein again.

Wherein the second out-coupling grating 220 comprises at least two sub-out-coupling gratings, 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 all three. And the intersection of two adjacent sub-outcoupling gratings in the second outcoupling grating 220 is located in the eye box260 of the optical structure 200. The diffraction efficiency of the sub-outcoupling grating of the second outcoupling grating 220 that is further away from the incoupling grating 240 is larger than the diffraction efficiency of the sub-outcoupling grating that is closer to the incoupling grating 240. So that the total energy of the light coupled out by the second out-coupling grating 220 is substantially the same, or the energy of the light coupled out by each sub-out-coupling grating of the second out-coupling grating 220 is understood to be substantially the same. And does not affect the intensity of the light coupled out by the second light-coupling grating 220.

The sub-outcoupling gratings of the second outcoupling grating 220 shown in fig. 20 are illustrated by way of example in three. 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 may refer to the first sub-outcoupling grating 231, the second sub-outcoupling grating 222 may refer to the third sub-outcoupling grating 233, and the third sub-outcoupling grating 223 may refer to the second sub-outcoupling grating 232, which will not be described herein again. It should be noted that, when the number of the sub-regions of the second coupling-out grating 220 and the number of the sub-regions of the third coupling-out grating 230 are both greater than three, referring to fig. 18 and 19, 2 sub-coupling-out gratings, 3 sub-coupling-out gratings or more sub-coupling-out gratings are arranged between the first sub-coupling-out grating 221 and the third sub-coupling-out grating 223, and the arrangement manner of the sub-coupling-out gratings is the same as that of the sub-coupling-out grating of the third coupling-out grating 230, and will not be described herein again.

It is understood that in some other embodiments of the present application, it is within the scope of the embodiments of the present application to arrange only any one of the first outcoupling grating 210, the second outcoupling grating 220, and the third outcoupling grating 230 in a partitioned manner. And only two of the first outcoupling grating 210, the second outcoupling grating 220 and the third outcoupling grating 230 are arranged in a zoned manner within the scope defined by the embodiments of the present application.

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 be two-dimensional gratings, such as those shown in fig. 1 to 15, which will not be described herein again. It should be noted that when the third outcoupling grating 230 includes a plurality of sub-outcoupling gratings, the first outcoupling grating 210 and the second outcoupling grating 220 may also adopt other grating structures such as a one-dimensional grating. When the first coupling-out grating 210 and the second coupling-out grating 220 are one-dimensional gratings, the third coupling-out grating 230 is two-dimensional grating, the coupling-in grating 240 is one-dimensional grating, the grating periods of the first coupling-out grating 210, the second coupling-out grating 220 and the coupling-in grating 240 are equal, and the grating period of the third coupling-out grating 230 along the arrangement direction of all the sub coupling-out gratings of the third coupling-out grating 230 is twice as long as that of any one of the first coupling-out grating 210, the second coupling-out grating 220 and the coupling-in grating 240.

The optical structure 200 defined in the above embodiments of the present application can be applied to an optical device, which can include a projection optical device and any of the above optical structures 200. The optical device may be an augmented reality device or a virtual reality device.

The optical structures and optical devices provided by the embodiments of the present application are described in detail above, and the principles and embodiments of the present application are described herein by applying specific examples, and the above description of the embodiments is only used to help understand the method and core ideas of the present application; meanwhile, for those skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.

Claims

1. An optical structure, comprising:

a waveguide;

the first light coupling grating is arranged on the waveguide body;

a second outcoupling grating disposed on the waveguide; and

the first direction is a direction in which the first outcoupling grating faces the second outcoupling grating, and the first direction is opposite to the second direction.

2. The optical structure of claim 1, further comprising an incoupling grating disposed on the same side of the first, second and third outcoupling gratings, wherein the incoupling grating and the third outcoupling grating are arranged side by side;

the first grid comprises four vertexes and can form a first diagonal line and a second diagonal line, the length of the first diagonal line is greater than that of the second diagonal line, an included angle between the first diagonal line and the third coupled-out grating in the third direction is an acute angle, and an included angle between the second diagonal line and the third coupled-out grating in the third direction is an obtuse angle;

wherein the third direction is a direction in which the third outcoupling grating faces the incoupling grating.

3. The optical structure of claim 1, further comprising an incoupling grating disposed on the same side of the first, second and third outcoupling gratings, wherein the incoupling grating and the third outcoupling grating are arranged side by side;

the first grid comprises at least five vertexes, the vertexes of the first grid comprise two vertexes close to the third coupling-out grating and two vertexes far away from the third coupling-out grating, the two vertexes close to the third coupling-out grating and the two vertexes far away from the third coupling-out grating can form a third diagonal line and a fourth diagonal line, the length of the third diagonal line is greater than that of the fourth diagonal line, an included angle between the third diagonal line and the third coupling-out grating in a fourth direction is an acute angle, and an included angle between the fourth diagonal line and the third coupling-out grating in the fourth direction is an obtuse angle;

wherein the fourth direction is a direction in which the third outcoupling grating faces the incoupling grating.

4. The optical structure of claim 1, further comprising an incoupling grating disposed on the same side of the first, second and third outcoupling gratings, wherein the incoupling grating and the third outcoupling grating are arranged side by side;

the first grid comprises three vertexes, and the first grid is provided with a first vertex connecting edge, a second vertex connecting edge and a third vertex connecting edge, the first vertex connecting edge is close to the third coupling-out grating, the second vertex connecting edge is far away from the third coupling-out grating, the length of the first vertex connecting edge is larger than that of the second vertex connecting edge, an included angle between the first vertex connecting edge and the third coupling-out grating in a fifth direction is an acute angle, and an included angle between the second vertex connecting edge and the third coupling-out grating in the fifth direction is an obtuse angle;

wherein the fifth direction is a direction in which the third outcoupling grating faces the incoupling grating.

5. An optical structure according to any one of claims 2 to 4, wherein the first outcoupling grating has a plurality of sets of grating groups, each set of grating groups including a plurality of the first gratings, and each first grating in each set of grating groups intersects with its neighboring first grating, the sets of grating groups being spaced apart from each other.

6. The optical structure of claim 5, the sets of grids being parallel to each other.

7. The optical structure according to claim 5, wherein the first gratings in each group of gratings are arranged along a sixth direction, the sixth direction is a direction rotated by 30 degrees along a clockwise direction along a seventh direction, and wherein the seventh direction is a direction of the third outcoupling grating toward the incoupling grating.

8. An optical structure according to any one of claims 1 to 4, characterized in that the second outcoupling grating and the first outcoupling grating are arranged axisymmetrically with respect to the third outcoupling grating, the second outcoupling grating being a two-dimensional grating having a plurality of second grids, all of the second grids of the second outcoupling gratings being identical in shape and arrangement to all of the first grids of the first outcoupling gratings.

9. An optical structure according to any one of claims 1 to 4, wherein the third outcoupling grating comprises at least two sub-outcoupling gratings, the junction of two adjacent sub-outcoupling gratings being located within the cell of the optical structure, the diffraction efficiency of the sub-outcoupling grating remote from the incoupling grating being greater than the diffraction efficiency of the sub-outcoupling grating close to the incoupling grating.

10. The optical structure of claim 9, wherein the third outcoupling grating comprises at least three sub-outcoupling gratings, the at least three sub-outcoupling gratings comprising a portion of a first sub-outcoupling grating located on one side of the eye-box, a portion of a second sub-outcoupling grating located on the other side of the eye-box, and at least one sub-outcoupling grating located entirely within the eye-box;

the length of the first 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 arrangement direction of all the sub-outcoupling gratings in the eye box;

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 located in the eye box along the arrangement direction of all the sub-outcoupling gratings.

11. An optical structure according to claim 9, wherein 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 that of the sub-out-coupling gratings of the third out-coupling grating, and the junction of two adjacent sub-out-coupling gratings of 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 away from the in-coupling grating of the first out-coupling grating is greater than that of the sub-out-coupling grating close to the in-coupling grating;

the second coupling-out grating comprises at least two sub coupling-out gratings, the number of the sub coupling-out gratings of the second coupling-out grating is the same as that of the sub coupling-out gratings of the third coupling-out grating, the junction of the two adjacent sub coupling-out gratings in the second coupling-out grating is located in the eye box of the optical structure, and the diffraction efficiency of the sub coupling-out grating far away from the coupling-in grating in the second coupling-out grating is greater than that of the sub coupling-out grating close to the coupling-in grating.

12. An optical structure according to any one of claims 2 to 4, characterised in that the third outcoupling grating is a two-dimensional grating having a plurality of third grids, the third grids being symmetrically shaped;

the first coupling-out grating, the second coupling-out grating and the third coupling-out grating are two-dimensional gratings, the grating periods of the first coupling-out grating, the second coupling-out grating and the third coupling-out grating are equal, and the refractive index of any one of the first coupling-out grating, the second coupling-out grating and the third coupling-out grating and the refractive index of the waveguide body are 1.5-3;

the grating period of the incoupling grating is one half of the grating period of the first outcoupling grating in a direction perpendicular to the first direction.

13. An optical structure, comprising:

a waveguide;

the first light coupling grating is arranged on the waveguide body;

a second outcoupling grating disposed on the waveguide;

14. An optical structure as claimed in claim 13, characterized in that at least a part of all sub-outcoupling gratings is located in an eye box.

15. The optical structure of claim 14, wherein the third outcoupling grating comprises at least three sub-outcoupling gratings, the at least three sub-outcoupling gratings comprising a portion of a first sub-outcoupling grating located on one side of the eye-box, a portion of a second sub-outcoupling grating located on the other side of the eye-box, and at least one sub-outcoupling grating located entirely within the eye-box;

the length of the first 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 located in the eye box along the arrangement direction of all the sub-outcoupling gratings;

16. An optical structure according to claim 15, wherein the sub-out-coupling gratings completely within the capsule are any one of one, two or three, and the diffraction efficiency of all the sub-out-coupling gratings increases in equal proportion from one sub-out-coupling grating closest to the in-coupling grating to one sub-out-coupling grating farthest from the in-coupling grating.

17. An optical structure according to claim 15, characterized in that the first and second sub-outcoupling gratings are arranged symmetrically with respect to a sub-outcoupling grating located completely within the capsule.

18. The optical structure according to claim 15, wherein the ratio of the length of the first or second sub-outcoupling grating in the direction in which all the sub-outcoupling gratings are arranged to the length of all the sub-outcoupling gratings is P1, and the ratio of the length of all the sub-outcoupling gratings completely located in the capsule in the direction in which all the sub-outcoupling gratings are arranged to the length of all the sub-outcoupling gratings is P2;

wherein P1 is greater than or equal to 30% and P1 is less than or equal to 45%, P2 is greater than or equal to 10% and P2 is less than 30%.

19. An optical structure according to any one of claims 13 to 18, wherein the first outcoupling grating comprises at least two sub-outcoupling gratings, the number of sub-outcoupling gratings of the first outcoupling grating is the same as the number of sub-outcoupling gratings of the third outcoupling grating, and the junction of two adjacent sub-outcoupling gratings in the first outcoupling grating is located in the eye box of the optical structure, and the diffraction efficiency of the sub-outcoupling grating of the first outcoupling grating that is far from the incoupling grating is greater than the diffraction efficiency of the sub-outcoupling grating that is close to the incoupling grating;

20. An optical structure according to any one of claims 13 to 18, wherein the third outcoupling grating is a two-dimensional grating, the incoupling grating is a one-dimensional grating, the third outcoupling grating has a grating period in the direction along which all the sub-outcoupling gratings of the third outcoupling grating are arranged that is twice the grating period of the incoupling grating, the first outcoupling grating and the second outcoupling grating are both one-dimensional gratings, or the first outcoupling grating and the second outcoupling grating are both two-dimensional gratings;

the refractive index of any one of the first coupling-out grating, the second coupling-out grating, the third coupling-out grating and the coupling-in 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;

and when the first coupling-out grating and the second coupling-out grating are two-dimensional gratings, the periods of the first coupling-out grating, the second coupling-out grating and the third coupling-out grating are equal.

21. An optical device, comprising:

an optical structure as claimed in any one of claims 1 to 20.