CN113777707B

CN113777707B - Optical structure and optical device

Info

Publication number: CN113777707B
Application number: CN202111089009.0A
Authority: CN
Inventors: 蒋楚豪
Original assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Current assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Priority date: 2021-09-16
Filing date: 2021-09-16
Publication date: 2024-02-13
Anticipated expiration: 2041-09-16
Also published as: WO2023040491A1; CN113777707A

Abstract

Embodiments of the present application provide an optical structure and an optical device, wherein the optical structure includes: a waveguide; the coupling grating is arranged on the 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, the third coupling-out grating is positioned between the first coupling-out grating and the second coupling-out grating, and the coupling-in grating is positioned on the same side of the first coupling-out grating, the second coupling-out grating and the third coupling-out grating; light rays emitted by the coupling-in grating are incident to the third coupling-out grating through the waveguide body and react with the third coupling-out grating to generate a first component of light rays including light rays along the light ray emitting direction, wherein the first component of light rays is kept within the range of the third coupling-out grating and cannot be conducted to the first coupling-out grating or the second coupling-out grating. The embodiment of the application can improve the diffraction efficiency of the optical structure.

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

An optical device such as an augmented Reality (Augmented Reality, abbreviated AR) device, a Virtual Reality (VR) device may display images through respective display devices. The related art of AR devices and/or VR devices is increasingly applied to various fields, such as fields of military, medical, construction, education, engineering, video, entertainment, etc.

Among them, AR glasses are one of the main implementations of AR devices, and its near-eye display system is to form a distant virtual image by a series of optical imaging elements from pixels on a display device and project the virtual image into human eyes. AR eyewear products need to meet the See-through (See-through) requirement, both to See the real world and to See virtual information, so the imaging system cannot be blocked in front of the line of sight. Such as adding one or a set of optical combiners, to integrate virtual information with the real scene in a "stacked" fashion.

In the related art, AR glasses have numerous optical implementation schemes such as catadioptric, reflective optical waveguide, one-dimensional diffractive optical waveguide, two-dimensional diffractive optical waveguide, holographic optical waveguide, etc., wherein the Two-dimensional diffractive optical waveguide (Two-dimensional Diffractive Waveguide, abbreviated as TDDW) is light and thin and has high transmission characteristics of external light, and the characteristics of good color reproducibility, large FOV, etc. are considered as the most promising optical scheme of consumer-grade AR glasses.

In the related art, a coupling-in grating of a general TDDW architecture couples light from a projection light machine into a waveguide, and the light coupled into the waveguide advances toward the coupling-out grating through total internal reflection, and after reaching the coupling-out grating, the light is split into a pupil-expanding light propagating leftwards and a pupil-expanding light propagating rightwards through diffraction. When the light acts on the coupling-out grating, a part of energy is coupled into human eyes, so that a user can see the picture of the projection optical machine. When the edge view ray is incident, the component generated by the edge view ray passing through the coupling-out grating includes a component transmitted along the propagation direction of the edge view ray, and the edge view ray passes through different coupling-out gratings in the actual propagation process, so that the diffraction efficiency is low.

Disclosure of Invention

The embodiment of the application provides an optical structure and an optical device, which can improve the diffraction efficiency of the optical structure.

Embodiments of the present application provide an optical structure comprising:

a waveguide;

the coupling grating is arranged on the waveguide body;

the first coupling-out grating is arranged on the waveguide body;

the second coupling-out grating is arranged on the waveguide body; and

the third coupling-out grating is arranged on the waveguide body, the third coupling-out grating is positioned between the first coupling-out grating and the second coupling-out grating, and the coupling-in grating is positioned on the same side of the first coupling-out grating, the second coupling-out grating and the third coupling-out grating;

Light rays emitted by the coupling-in grating are incident to the third coupling-out grating through the waveguide body and react with the third coupling-out grating to generate a first component of light rays including light rays along the light ray emitting direction, wherein the first component of light rays is kept within the range of the third coupling-out grating and cannot be conducted to the first coupling-out grating or the second coupling-out grating.

Embodiments of the present application also provide an optical device, comprising:

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

an optical structure as claimed in any preceding claim.

In the embodiment of the present application, when light is emitted from the coupling-in grating and enters the third coupling-out grating through the waveguide body, the light can act with the third coupling-out grating to generate a first component of the light along the light emitting direction, and the first component of the light can be kept within the range of the third coupling-out grating and is not conducted to other components such as the first coupling-out grating or the second coupling-out grating, so that the diffraction efficiency of the optical structure can be improved.

Drawings

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

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

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

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

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

Fig. 6 is a schematic diagram of central view ray transmission along a plane in an optical structure according to an embodiment of the present application.

Fig. 7 is a schematic diagram of edge view light transmitted along a plane in an optical structure according to an embodiment of the present disclosure.

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

Fig. 9 is a schematic diagram of a grating vector of a first coupling-out grating according to an embodiment of the present application.

Fig. 10 is a schematic diagram of an optical structure and a partial structure of a first coupling-out grating in the optical structure according to an embodiment of the present application.

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

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

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

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

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

Fig. 16 is a schematic view of an optical structure according to an embodiment of the present application.

Fig. 17 is a schematic view of an optical structure according to an embodiment of the present application.

Fig. 18 is a schematic view of an optical structure according to an embodiment of the present application.

Fig. 19 is a schematic view of an optical structure according to an embodiment of the present application.

Fig. 20 is a schematic view of an optical structure according to an embodiment of the present application.

Fig. 21 is a schematic view of an optical structure according to an embodiment of the present application.

Fig. 22 is a schematic diagram of an optical structure according to an embodiment of the present application.

Fig. 23 is a schematic view of an optical structure according to an embodiment of the present application.

Fig. 24 is a schematic view of an optical structure according to 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 will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by a person skilled in the art without any inventive effort, are intended to be within the scope of the present application based on the embodiments herein.

Referring to fig. 1, fig. 1 is a schematic structural diagram of an optical structure according to an embodiment of the present application, and shows a reference system (x, y, z). 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). 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 x-y plane.

Wherein the waveguide 250 acts as a carrier for the optical structure 200. Waveguide 250 is capable of conducting optical signals, such as by way of total internal reflection. The waveguide 250 may have two oppositely disposed surfaces, such as including oppositely disposed first and second surfaces 252, 252. Wherein the second surface is disposed opposite the first surface 252 and is obscured from view in fig. 1.

Wherein the in-coupling grating 240 is disposed on one of the surfaces of the waveguide 250, such as the first surface 252. The coupling-in grating 240 may receive an optical signal (also referred to as light) from a projection light engine (not shown) and couple the optical signal into the waveguide 250. The waveguide 250 may conduct the optical signal coupled in from the coupling-in grating 240 upon receiving the optical signal.

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

The plurality of out-coupling gratings may include a first out-coupling grating 210, a second out-coupling grating 220, and a third out-coupling 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 disposed 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 side 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 be disposed on the other surface of the waveguide 250, i.e., the second surface opposite to the first surface.

In other embodiments, one of the first, second and third outcoupling gratings 210, 220 and 230 may be disposed on one side of the waveguide 250, such as the first surface 252, and the other two of the first, second and third outcoupling gratings 210, 220 and 230 may be disposed on the other and second surfaces of the waveguide 250. It is understood that any combination 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 is disposed on any surface of the waveguide 250, and is within the scope of the embodiments of the present application.

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

The waveguide 250 may make the optical signal coupled into the coupling-in grating 240 proceed 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 is split into several parts and conducted toward multiple directions through diffraction. 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 optical machine.

Referring to fig. 2, fig. 2 is a perspective view of an optical structure according to an embodiment of the present application, and fig. 2 shows a transmission case of an optical signal after a central field of view ray is incident and diffracted, and shows a reference system (x, y, z). After the light of the central field of view is incident on the in-coupling grating 240, the in-coupling grating 240 transmits the light 201 toward the third out-coupling grating 230 via the waveguide 250. Light 201 is split into 4 beams after being diffracted by the third outcoupling grating 230, light 2011, light 2012, light 2013 and light 2014, respectively.

Ray 2011 follows the original path of ray 201. It can be appreciated that the light ray 201 is split into 4 light beams after being diffracted by the third coupling-out grating 230, and the light ray 2011 is split into 4 light beams after being diffracted by the third coupling-out grating 230 multiple times during the traveling along the original path of the light ray 201. That is, the light 2011 is diffracted by the third coupling-out grating 230 to split into a plurality of light rays 2013, a plurality of light rays 2014 and a plurality of 2011 when traveling along the original path of the light ray 201, and the plurality of 2011 is all shown as one light ray when traveling along the original path of the light ray 201. The energy of the light rays traveling along the original path decreases each time the light rays 2011 interact with the third outcoupling grating 230.

Light 2012 is directly coupled out of the third coupling-out grating 230, which is understood to mean that light 2012 is coupled out in the positive direction of z based on the x-y plane. The light directly coupled out from the third coupling-out grating 230 is defined as light 2012 in its entirety. It will be appreciated that the energy of the different light rays directly coupled out from different positions of the third outcoupling grating 230 is different.

Light 2013 is split into 2 beams, light 2013A and light 2013B, respectively, by diffraction after acting on the first outcoupling grating 210. Light 2013A is directly coupled out of the first coupling-out grating 210, which can be understood that light 2013A is coupled out in a positive direction toward z based on the x-y plane. Light 2013B proceeds along the original path of light 2013. The light propagating from the third outcoupling grating 230 toward the first outcoupling grating 210 is defined as light 2013, where the light 2013 has a plurality of light rays, and each light ray 2013 is diffracted to split into a plurality of light rays 2013A and a plurality of light rays 2013B after acting on the first outcoupling grating 210. It will be appreciated that the different light rays 2013 differ in energy, the different light rays 2013A differ in energy, and the different light rays 2013B differ in energy.

Light 2014 is split into 2 beams of light after being diffracted by the second outcoupling grating 220, namely light 2014A and light 2014B, wherein light 2014A is directly coupled out of the second outcoupling grating 210, which can be understood that light 2014A is coupled out in the positive direction of z based on the x-y plane. Light 2014B follows the original path of light 2014. The light propagating from the third outcoupling grating 230 toward the second outcoupling grating 220 is defined as light 2014, where the light 2014 has a plurality of light rays, and each light ray 2014 is diffracted to split into a plurality of light rays 2014A and a plurality of light rays 2014B after acting on the second outcoupling grating 220. It will be appreciated that the different light rays 2014 have different energies, the different light rays 2014A have different energies, and the different light rays 2014B have different energies.

Light coupled out from the positive direction of the z based on the x-y plane is incident into human eyes, so that a user can see the picture of the projection light machine. With continued reference to fig. 2, in the example shown in fig. 2, the light 2012 coupled out from the third outcoupling grating 230 in the positive direction z is injected into the human eye, the light 2013A coupled out from the first outcoupling grating 210 in the positive direction z is injected into the human eye, and the light 2014A coupled out from the second outcoupling grating 220 in the positive direction z is injected into the human eye.

It should be noted that, the light 2011, the light 2012, the light 2013, and the light 2014 shown in fig. 2 are exemplary, and the number of light coupled out by the optical structure 200 is not limited. Or it should be understood that fig. 2 illustrates a portion of light rays of the optical structure 200 of the embodiment of the present application when coupling out light rays, and the remaining light rays are not illustrated.

Referring to fig. 3 and fig. 4, fig. 3 is a schematic diagram of transmission of central field light in an optical structure according to an embodiment of the present application, and fig. 4 is a schematic diagram of transmission of edge field light in an optical structure according to an embodiment of the present application. The light 201 coupled out by the in-coupling grating 240 is transmitted to the third out-coupling grating 230 through the waveguide 250, and acts with the third out-coupling grating 230 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 rays 2011, 2012, 2013 and 2014 can be referred to in fig. 2 and related contents, and are not repeated herein. Note that ray 2012 is replaced with a dot in the x-y plane. Light 2013 and the first outcoupling grating 210 act to split a plurality of light rays such as light ray 2013A and 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. Note that, in the x-y plane, light 2013A is replaced with a dot. Light 2014 and the second outcoupling grating 220 act to split a plurality of light rays such as light ray 2014A and light ray 2014B, and the light ray 2014A and the light ray 2014B can refer to fig. 2 and related contents, which are not described herein. Note that, in the x-y plane, light 2014A is replaced with a dot. As can be seen schematically in fig. 3 and 4, each dot represents a light ray that acts with a coupling-out grating, and the light ray represented by the dot may be incident into the human eye.

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

It should be noted that only a portion of the light rays indicated by the dots in fig. 3 and 4 are incident to human eyes.

Referring to fig. 5, fig. 5 is a schematic diagram of an optical structure light transmission process in k-space according to an embodiment of the present application, and shows reference systems (kx, ky, kz). The two circle radii shown in fig. 5 are the ambient refractive index and the waveguide sheet refractive index, respectively, wherein the small circle radius, i.e., the circle radius located at the inner circle, is the ambient refractive index, and the large circle radius, i.e., the outer circle radius, is the waveguide refractive index. Rectangles denote fields of view (FOV), each rectangle representing a field of view, rectangles in different positions representing different states of light of the field of view, such as a circular center rectangle representing the incident or coupled-out light (ray 2012, ray 2013A, ray 2014A) from the projector to the waveguide body 250, and a circular inside (i.e., between two circles) rectangle representing the light of the field of view propagating in the waveguide body 240 after being coupled through the gratings (first coupling-out grating 210, second coupling-out grating 220, and coupling-in grating 240). If the field of view is within a small circle it means that light can be coupled out of the waveguide 250, if the field of view is within a circle it means that light is propagating within the waveguide 250, whereas if the field of view is outside a large circle it means that light is not actually present. The field of view is coupled into the waveguide 250 at the origin of coordinates by diffraction k1 through the coupling-in grating 240, and then the ray 201 is changed to 6 different positions around its k-space by the 6 diffraction components k22 of the third coupling-out grating 230, wherein the rays 2013, 2014 are also in a circle, representing that they will propagate by total internal reflection to the left and right, respectively, along the kx-axis, as mydriatic rays. Still a portion of the rays will translate upward via diffraction, coincident with the original incident image, representing that they (such as ray 2012) will be directly coupled out. The remaining 3 positions are outside the circle, meaning that these 3 diffraction components are not present. Not all of the energy of ray 201 is diffracted, but instead it leaves most of the energy unchanged, which means that most of the energy continues to propagate through total internal reflection along the propagation direction of ray 201.

The area where the optical structure 200 is coupled out and injected into the human eye is defined as an eye box (Eyebox) 260 in the embodiments of the present application. I.e., light rays within the eye box 260 that are coupled out in the positive z-axis direction, will strike the human eye.

The eye box will be described below.

Referring to fig. 6 to fig. 8, fig. 6 is a schematic diagram of central view field light transmitted along a plane by the optical structure according to the embodiment of the present application, fig. 7 is a schematic diagram of edge view field light transmitted along a plane by the optical structure according to the embodiment of the present application, and fig. 8 is a schematic diagram of application scenario of the optical structure according to the embodiment of the present application. Assuming that the incident field of view is in the range of-a deg. to a deg. from the z-axis in the y-z plane, i.e. the incident maximum field of view F2 is in the range of a deg. from the z-axis in the y-z plane, the incident minimum field of view F1 is in the range of-a deg. from the z-axis in the y-z plane. The distance from the human eye to the waveguide 250 (eyeelief) is b, i.e., the distance from the Eyebox plane or the human eye viewing plane to the waveguide 250 is b. The length of the eye box 260 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, 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.

In an alternative embodiment of the present application, the center of the eye box 260 may coincide with the center of the third out-coupling grating 230.

With continued reference to fig. 2, 3 and 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, second and third outcoupling gratings 210, 220 and 230, such as light 2012, 2013A and 2014A, is incident on the eye box 260.

With continued reference to fig. 4 and 7, when the edge field light is incident on the optical structure 200, only a portion of the light 2012 and a portion of the light 2014A coupled out by the second and third outcoupling gratings 220 and 230 are in the eye box 260, and substantially all of the light 2013A coupled out by the first outcoupling grating 210 is not in the eye box 260. In other words, the energy of the light coupled out by the second and third outcoupling gratings 220 and 230 is utilized, and the energy of the light coupled out by the first outcoupling grating 210 is wasted, which tends to result in poor exit pupil uniformity of the fringe field of view.

In addition, in the waveguide architecture in the related art, the exit pupil uniformity of the edge field of view is significantly worse than that of the center field of view, which means that when the projection optical engine picture is viewed at some Eyebox positions, the difference between the brightness of the center field of view and the brightness of the edge field of view will be relatively large, which causes discomfort to the user in viewing.

The first outcoupling grating 210 defined in the embodiments of the present application adopts a two-dimensional grating structure and has a plurality of first gratings, and each of the first gratings has an asymmetric shape, so that the light efficiency of the first outcoupling grating 210 propagating in the first direction is higher than the light efficiency of the first outcoupling grating 210 propagating in the second direction. The energy of the wasted portion of the light coupled out by the first coupling-out grating 210 is smaller than that of other light, so that the exit pupil brightness and the exit pupil uniformity of each view field can be improved, and the difference between the energy of each view field can be reduced. Such as improving exit pupil brightness and exit pupil uniformity of the fringe field of view, reducing the difference between fringe field energy and center field energy. Especially, when the optical structure 200 is applied to a head-mounted display product such as 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 the direction of the first outcoupling grating 210 toward the second outcoupling grating 220, such as the negative direction of the x-axis shown in fig. 1. The second direction is the direction in which the second outcoupling grating 220 faces 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 in the embodiment of the application are opposite.

Referring to fig. 9, fig. 9 is a schematic diagram of a grating vector of a first coupling-out grating according to an embodiment of the present application. 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 (1, 0) and (-1, 0) orders of the first outcoupling grating 210 diffract with significantly higher efficiency than the (0, 1) and (0, -1) orders, and when the light ray 201 is incident on the first outcoupling grating 210, the light ray 2014B is generated by the (-1, 0) order diffraction of the first outcoupling grating 210, and the light ray 2013B is generated by the (0, 1) order diffraction of the first outcoupling grating 210, so that the light ray 2014B propagating to the left (first direction) in the figure is significantly more efficient than the light ray 2013B propagating to the right (second direction) in the figure.

For purposes of describing the asymmetric shape employed by first grating 212 in the embodiments of the present application, it is possible to make the light efficiency of first outcoupling grating 210 propagating in the first direction higher than the light efficiency of first outcoupling grating 210 propagating in the second direction. The following is described in connection with a schematic diagram of the first outcoupling grating 210.

Referring to fig. 10 to 13, fig. 10 is a schematic diagram of a partial structure of an optical structure and a first outcoupling grating in the optical structure provided in the embodiment of the present application, fig. 11 is a schematic diagram of a partial structure of the first outcoupling grating in the optical structure provided in the embodiment of the present application, fig. 12 is a schematic diagram of a partial structure of the first outcoupling grating in the optical structure provided in the embodiment of the present application, and fig. 13 is a schematic diagram of a partial structure of the first outcoupling grating in the optical structure provided in 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 part M are part of the first grids 212 of the first outcoupling grating 210.

All 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, vertex f, which may form a first diagonal ce and a second diagonal df. The length of the first diagonal ce is greater than that of the second diagonal df, and the 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 the included angle θacy between the second diagonal bd and the third out-coupling grating in the third direction is an obtuse angle.

Wherein the third direction is the direction in which the third out-coupling grating 230 faces the in-coupling grating 240.

In an alternative embodiment of the present application, first grids 212 of the same shape are periodically arranged in a hexagonal lattice on the x-y plane, and have two periodic directions, i.e., a periodic direction a and a periodic direction b, respectively, and an included angle of 30 ° is formed between the periodic direction a and the periodic direction b. Wherein the period direction a is parallel to the y-axis, the distance between the 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 the 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 adopted by first grid 212 in this embodiment may also be understood as a shape in which first grid 212 is asymmetric about both x-axis and y-axis, first diagonal ce of first grid 212 is always longer than second diagonal df, and first diagonal ce forms an obtuse angle with positive y-axis direction θacy and forms an acute angle with positive x-axis direction θ acx.

The first coupling-out grating 210 has a plurality of grating groups 211, each grating group 211 including a plurality of first gratings 212, and each first grating 212 of each grating group 211 intersects its neighboring first gratings 212, the grating groups 211 being 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 respective 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 diagonally adjacent to the top right and bottom left.

The sixth direction is a direction in which the seventh direction is rotated 30 degrees in the clockwise direction, wherein the seventh direction is a direction in which the third out-coupling grating 230 faces the in-coupling grating 240. The seventh direction may be understood as a positive direction of Pa, that is, a direction in which 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 vertices or more. The embodiment of the present application will be described with 5 vertices as an example.

Referring to fig. 14, fig. 14 is a schematic partial structure diagram of a first coupling-out 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 out-coupling grating 230 and two vertices (vertex e and vertex f) far 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) far from the third out-coupling grating 230 can form a third diagonal ce and a fourth diagonal df, the length of the third diagonal ce is greater than the length of the fourth diagonal df, and the included angle between the third diagonal ce and the third out-coupling grating 230 in the fourth direction is an acute angle, and the included angle between the fourth diagonal df and the third out-coupling grating 230 in the fourth direction is an obtuse angle.

Wherein the fourth direction is the direction in which the third out-coupling grating 230 faces the in-coupling grating 240. I.e. the fourth direction, can 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, and are not described herein. 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, and are not described herein.

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

Referring to fig. 15, fig. 15 is a schematic partial structure diagram of a first coupling-out grating in an optical structure according to an embodiment of the present application. The vertices of the first grid 212 include a vertex c, a vertex d, and a vertex e, wherein the vertex c, the vertex d, and the vertex e are connected 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 coupling-out grating 230, the second vertex connecting edge de is far away from the third coupling-out grating 230, the length of the first vertex connecting edge cd is greater than the length of the second vertex connecting edge de, an included angle between the first vertex connecting edge cd and the third coupling-out grating 230 in the fifth direction is an acute angle, and an included angle between the second vertex connecting edge de and the third coupling-out grating 230 in the fifth direction is an obtuse angle.

Wherein the fifth direction is the direction in which the third out-coupling grating 230 faces the in-coupling grating 240. I.e. the fifth direction, can be understood as the third direction. The first vertex connecting edge cd and the second vertex connecting edge de can refer to the third diagonal line ce and the fourth diagonal line df shown in fig. 11 to 13, and 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, and are not described herein.

In the embodiment of the present application, the shapes of the first outcoupling grating 210 and the second outcoupling grating 220 are the same, and the first outcoupling grating 210 and the second outcoupling grating 220 are symmetrically disposed with respect to the third outcoupling grating 230, which can also be understood that the first outcoupling grating 210 and the second outcoupling grating 220 are mirror-image disposed with respect to the third outcoupling grating 230. That is, the plurality of grids in the second coupling-out grating 220 are 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 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 in the second outcoupling grating 220 being the same shape and arrangement as all of the first grids in the first outcoupling grating 210. The specific shape and arrangement can be seen in fig. 11 to 15, and will not be described here again.

The third out-coupling grating 230 is a two-dimensional grating having a plurality of third gratings, and the third gratings are symmetrically shaped, such as two-dimensional gratings having a bilateral symmetry, so that the light propagating leftwards is opposite to the light propagating rightwards, which is beneficial to increase the size of the eye box 260 with an edge angle of view. The third grid may be arranged in a hexagonal lattice and the grating vectors may be seen in fig. 9, with the (1, 1) diffraction order vectors parallel to the y-axis. The third grid may be any shape symmetrical along the y-axis, such as circular, positive, diamond, hexagonal, octagonal, etc. The area of the third outcoupling grating 230 may be rectangular, e.g. 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-35mm.

In an alternative 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 in-coupling grating 240 is one 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. Or the grating period of the in-coupling grating 240 is one 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.

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

With continued reference to fig. 2, the display brightness at each location within the Eyebox260 is determined by the intensity of the coupled light at that location, so the intensities of light 2012, light 2013A, light 2014A directly determine the display quality of the Eyebox 260. In practical applications, the intensity of the light 2012 is substantially weaker than that of the light 2013A and the light 2014A, so that the position of the corresponding light 2012 in the Eyebox260 presents a distinct dark area, which greatly affects the consumer's experience. The reason why the intensity of the light 2012 is weaker than that of the light 2013A and the light 2014A is that the coupling-out efficiency of the third coupling-out grating 230 cannot be set to be too high, otherwise the chief ray 201 attenuates too fast during the propagation process, the too fast attenuated light 201 causes the light intensity difference between the light 2012, and the luminance of the Eyebox260 is more seriously uneven.

Based on this, the present embodiment proposes an optical structure to improve the light out-coupling efficiency of the third out-coupling grating 230 without causing the intensity difference between the light 2012, such as the optical structure 200 of the present embodiment divides the third out-coupling grating 230 into a plurality of regions along the y-axis, the efficiency between the different regions is gradually improved along the y-axis, so that the efficiency of the corresponding out-coupling grating of 2012 even more subsequent out-coupling light is gradually improved although the principal light 201 is attenuated during the propagation process, so that the efficiency of the principal light 201 is accelerated and attenuated due to the improvement of the efficiency of the third out-coupling grating 230, but the energy difference between the light 2012 even more subsequent out-coupling light can be reduced, so that the energy of the light 2012 is more similar to the intensity difference between the light 2012 of the light 2013A and the light 2014A while the intensity difference between the light 2012 is reduced, and finally the brightness and the brightness uniformity of the Eyebox260 are improved, and both the energy and the brightness uniformity of the Eyebox260 are greatly improved. In summary, the present embodiment introduces a technique of dividing the third coupling-out grating 230 into multiple gratings, which solves the above problem, so that both the energy and the brightness uniformity of the Eyebox260 are greatly improved, and thus the present embodiment has a great implementation meaning, and is a diffraction waveguide architecture with excellent performance.

The third outcoupling grating 230 in this embodiment includes at least two sub-outcoupling gratings, where the junction between two adjacent sub-outcoupling gratings is located in the eye box 260 of the optical structure 200, and the diffraction efficiency of the sub-outcoupling grating far from the incoupling grating 240 is greater than that of the sub-outcoupling grating near the incoupling grating 240. The overall energy of the light coupled out by the third outcoupling grating 230 may be substantially the same, or it may be understood that the energy of the light coupled out by each sub-outcoupling grating of the third outcoupling grating 230 is substantially the same. And does not affect the intensity of the light coupled out by the third coupling-out grating 230. The following is a detailed description with reference to the drawings.

In an alternative implementation manner of this embodiment, the depth of the grating of the sub-coupling-out grating far from the coupling-in grating 240 is greater than the depth of the grating of the sub-coupling-out grating close to the coupling-in grating 240, so that the diffraction efficiency of the sub-coupling-out grating far from the coupling-in grating 240 can be greater than the diffraction efficiency of the sub-coupling-out grating close to the coupling-in grating 240. I.e., the deeper the grating of the optical structure 200 defined by an alternative embodiment of the present application, the higher its 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 an optical structure provided in an embodiment of the present application. The third outcoupling grating 230 of the optical structure 200 may comprise three sub-outcoupling gratings, each of which has at least a portion located within the eye-box 260. Such as third outcoupling grating 230, includes a portion of first sub-outcoupling grating 231 located on one side of eye box 260, a portion of second sub-outcoupling grating 232 located on the other side of eye box 260, and third sub-outcoupling grating 233 located entirely within eye box 260.

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

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

In an alternative embodiment of the present application, the length of the second sub-outcoupling grating 232 along the arrangement direction of all sub-outcoupling gratings may be equal to the length of the first sub-outcoupling grating 231 along the arrangement direction of all sub-outcoupling gratings. The first sub-outcoupling grating 231 and the second sub-outcoupling grating 232 may be symmetrically disposed 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 be unequal.

In this embodiment, the lengths of the first sub-coupling-out grating 231 along the arrangement direction of all the sub-coupling-out gratings and the lengths of the second sub-coupling-out grating 232 along the arrangement direction of all the sub-coupling-out gratings are greater than the lengths of the third sub-coupling-out grating 233 along the arrangement direction of all the sub-coupling-out gratings. In an alternative embodiment of the present application, the ratio of the length of the first sub-outcoupling grating 231 along the direction of arrangement of all sub-outcoupling gratings to the length of arrangement of all 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-coupling-out grating 233 along the arrangement direction of all the sub-coupling-out gratings to the length of all the sub-coupling-out gratings is P2, that is, the ratio of the length of the third sub-coupling-out grating 233 along the y-axis direction to the length of the third coupling-out grating 230 along 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 inside the eye box 260 is the same size as the portion of the second sub-outcoupling grating 232 located inside the eye box 260. Referring to fig. 5 and 6, the boundary of the sub-outcoupling 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.

In an alternative embodiment of the present application, the diffraction efficiency of all sub-outcoupling gratings increases equally from one sub-outcoupling grating closest to the incoupling grating 240, such as the first sub-outcoupling grating 231, to one sub-outcoupling grating furthest from the incoupling grating 240, such as the second sub-outcoupling grating 232. It is also understood that the diffraction efficiency of all sub-outcoupled gratings increases in equal proportion along the positive y-axis direction. For example, the diffraction efficiency of the third sub-outcoupling grating 233 is n times 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 higher than that of the third sub-outcoupling grating 233. Thereby ensuring that the energy of the light rays coupled out by each sub-diffraction grating is not greatly different.

It should be noted that the third outcoupling grating 230 shown in fig. 16 and 17 is only exemplary and not limited to the number 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, and so on. The greater number of sub-outcoupling gratings is not described here.

It should be further noted that, when the number of sub-outcoupling gratings of the third outcoupling grating 230 is greater than three, such as four and five, it is still satisfied that the boundary between 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 incoupling grating 240 is greater than that of the sub-outcoupling grating near the incoupling grating 240. The total energy of the light coupled out by the third outcoupling grating 230 may be approximately the same, or it may be understood that the energy of the light coupled out by each sub-outcoupling grating of the third outcoupling grating 230 is approximately the same. And does not affect the intensity of the light coupled out by the third coupling-out grating 230.

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

In contrast to fig. 16 and 17, the ratio of the sum of the lengths of at least two sub-outcoupling gratings of the third outcoupling grating 230, which are entirely within the eye box 260, in the y-axis direction to the length of the third outcoupling grating 230 in the y-axis direction is P2. The remaining features may be seen in fig. 16 and 17 and are not described in detail herein.

Referring to fig. 18, fig. 18 is a schematic diagram of an optical structure according to an embodiment of the present application. Fig. 18 illustrates 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 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 application. Fig. 19 illustrates that the third outcoupling grating 230 includes five sub-outcoupling gratings, which are 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, respectively, wherein the first sub-outcoupling grating 231 and the second sub-outcoupling grating 232 are not described herein again. The third sub-outcoupling grating 233, the fourth sub-outcoupling grating, and the fifth sub-outcoupling grating are all located within the eye box 260.

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

Referring to fig. 20, fig. 20 is a schematic diagram of an optical structure according to an embodiment of the present application. 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 disposed in equal regions. The arrangement of the third coupling-out grating 230 in the sub-regions can be seen in fig. 16 to 19, and will not be described here again.

The first outcoupling grating 210 includes at least two sub-outcoupling gratings, and the number of sub-outcoupling gratings of the first outcoupling grating 210 is the same as that of the third outcoupling grating 230, such as three. And the junction of two adjacent sub-outcoupling gratings in the first outcoupling grating 210 is located within the eye-box 260 of the optical structure 200. The diffraction efficiency of the sub-outcoupling gratings of the first outcoupling grating 210, which are far from the incoupling grating 240, is greater than the diffraction efficiency of the sub-outcoupling gratings, which are near to the incoupling grating 240. The overall energy of the light coupled out by the first outcoupling grating 210 may be substantially the same, or it may be understood that the energy of the light coupled out by each sub-outcoupling grating of the first outcoupling grating 210 is substantially the same. And does not affect the intensity of the light coupled out by the first coupling-out grating 210.

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

The second outcoupling grating 220 includes at least two sub-outcoupling gratings, and the number of sub-outcoupling gratings of the second outcoupling grating 220 is the same as that of the third outcoupling grating 230, such as three. And the junction of two adjacent sub-outcoupling gratings in the second outcoupling grating 220 is located within the eye-box 260 of the optical structure 200. The diffraction efficiency of the sub-outcoupling gratings of the second outcoupling grating 220, which are far from the incoupling grating 240, is greater than the diffraction efficiency of the sub-outcoupling gratings, which are near to the incoupling grating 240. The overall energy of the light coupled out by the second outcoupling grating 220 may be substantially the same, or it may be understood that the energy of the light coupled out by each sub-outcoupling grating of the second outcoupling grating 220 is substantially the same. And does not affect the intensity of the light coupled out by the second coupling-out grating 220.

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

It is understood that in other embodiments of the present application, only any one of the first outcoupling grating 210, the second outcoupling grating 220, and the third outcoupling grating 230 is disposed in a zoned 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 disposed in a zoned manner, which is also within the scope defined in 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 are not described herein. 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 employ other grating structures, such as a one-dimensional grating. When the first and second outcoupling gratings 210 and 220 employ one-dimensional gratings, the third outcoupling grating 230 employs a two-dimensional grating, the incoupling grating 240 employs a one-dimensional grating, the grating periods of the first and second outcoupling gratings 210 and 220 and the incoupling grating 240 are equal, and the grating period of the third outcoupling grating 230 in the arrangement direction along all sub-outcoupling gratings of the third outcoupling grating 230 is twice as long as any one of the first and second outcoupling gratings 210 and 220 and the incoupling grating 240.

Referring to fig. 21, fig. 21 is a schematic diagram of an optical structure according to an embodiment of the disclosure. The optical structure 300 shown in fig. 21 includes an in-coupling grating 340, a first out-coupling grating 320, a second out-coupling grating 320, a third out-coupling grating 330, and a waveguide 350. The in-grating 340, the first out-grating 320, the second out-grating 320, and the third out-grating 330 are all disposed on the waveguide 340, and any of the in-grating 340, the first out-grating 320, the second out-grating 320, and the third out-grating 330 may be disposed on any side of the waveguide 350, such as the in-grating 340, the first out-grating 320, the second out-grating 320, and the third out-grating 330 are all disposed on the first side 352 of the waveguide 350.

The waveguide 350 may refer to the waveguide 250, and is not described herein. The coupling grating 340 may refer to the coupling grating 240, and is not described herein.

Referring to fig. 22, fig. 22 is a schematic diagram of an optical structure according to an embodiment of the disclosure. Referring to fig. 21, an optical structure 300 according to an embodiment of the present application includes components that remain within the range of the third outcoupling grating 330 and do not propagate to the first outcoupling grating 310 or the second outcoupling grating 320, such as edge angle light, for example, light propagating through the third outcoupling grating 330.

For example, the light 301 emitted from the in-grating 340 with an edge angle of view enters the third out-grating 330 via the waveguide 350 and reacts with the third out-grating 330 to generate a first component 304 of the light along the outgoing direction of the light 301, and the first component 304 of the light remains within the range of the third out-grating 330 and is not conducted to the first out-grating 310 or the second out-grating 320.

It should be noted that, the edge angle light 301 may also generate other light components when the third coupling-out grating 330 is applied, such as a second component of light propagating along the z-axis direction, a third component of light propagating along the x-axis forward direction, and a fourth component of light propagating along the x-axis reverse direction. The first light component 304 reacts with the third outcoupling grating 320 multiple times during actual conduction to reform multiple light components.

With continued reference to fig. 21 and 22, the third out-coupling grating 330 may include a first side 3301 and a second side 3302, where the first side 3301 is far from the in-coupling grating 340, the second side 3302 is near the in-coupling grating 340, and the first side 3301 and the second side 3302 are opposite to each other. The length of the first side 3301 along the arrangement direction of the first coupling-out grating 320, the second coupling-out grating 320, and the third coupling-out grating 330 is greater than the length of the second side 3302 along the arrangement direction of the first coupling-out grating 320, the second coupling-out grating 320, and the third coupling-out grating 330. To ensure that the first component 304 of light remains within the range of the third out-coupling grating 330. For example, the first side 3301 may be greater than 10 millimeters in length and the second side 3302 may be greater than 4 millimeters in length.

For example, referring to fig. 23, fig. 23 is a schematic diagram of an optical structure according to an embodiment of the present application. Assuming that the angle between the x-z plane and the z-axis of the light ray 301 incident on the coupling-in grating 340 is a and the angle between the y-z plane and the z-axis is b, the light vectors of the first light component 304 of the incident light ray coupled in by the coupling-in grating 340 in the x-direction and the y-direction are:

then the ray first component 304 of the incident ray is at an angle to the y-axis of:

the length B of the second side 3302 of the third outcoupling grating 330 needs to satisfy the following relation:

B≥2C*tan(θ)+A

the length E of the first side 3301 of the third outcoupling grating 330 needs to satisfy the following relationship:

E≥2D*tan(θ)+A

thus, embodiments of the present application may ensure that the first component 304 of the incident light ray remains within the range of the third out-coupling grating 330.

In an alternative embodiment of the present application, the width of the third out-coupling grating 330 gradually decreases from the first side 3301 to the second side 3302. I.e. the width of the third outcoupling grating 330 gradually increases from the second side 3302 to the first side 3301. The width of the third outcoupling grating 330 is the length of the third outcoupling grating 330 along the arrangement direction of the first outcoupling grating 310, the third outcoupling grating 330 and the second outcoupling grating 320. Such as length along the x-axis. Such as the third out-coupling grating 330, is overall in the form of an isosceles trapezoid. It should be noted that the shape of the third out-coupling grating 330 in the embodiment of the present application is not limited to the shape of the third out-coupling grating 330, as long as the length of the first side 3301 is longer than the length of the second side 3302, and all the shapes of the third out-coupling grating 330 are within the protection scope of the embodiment of the present application.

The third outcoupling grating 330 may further include a third side 3303 and a fourth side 3304. The third side 3303 and the fourth side 3304 are disposed opposite to each other, and it is understood that the third side 3303 and the fourth side 3304 are disposed at opposite sides of the third outcoupling grating 330, and the first side 3301 and the second side 3302 are disposed at opposite ends of the third outcoupling grating 330. The third side 3303 is connected to the first side 3301 and the second side 3302, such as the third side 3303 connects one end of the first side 3301 and one end of the second side 3302. The fourth side 3304 is connected to the first side 3301 and the second side 3302, such as the fourth side 3304 connecting the other end of the first side 3301 and the other end of the second side 3302.

In an alternative embodiment of the present application, the third side 3303 and the fourth side 3304 are disposed axisymmetrically with respect to the first side 3301 and the second side 3302.

In an alternative embodiment of the present application, the first side 3301 and the second side 3302 may be spaced from 20 millimeters to 35 millimeters.

In an alternative embodiment of the present application, the third out-coupling grating 330 is a two-dimensional grating with a square lattice structure. The first out-coupling grating 310, the second out-coupling grating 320, and the third out-coupling grating 330 may be made to have no pupil expansion area near one side edge of the in-coupling grating 340, such as the first out-coupling grating 310, the second out-coupling grating 320, and the third out-coupling grating 330 are made to be flush near one side edge of the in-coupling grating 340, which may be useful when it receives light coupling. Therefore, compared with an optical structure needing to arrange a pupil expansion region, an invalid grating region (namely the pupil expansion region) is saved, so that the overall effective coupling-out grating area of the optical structure 300 is increased, the utilization rate of the grating region is higher, and the overall efficiency of the diffraction waveguide is improved.

It should be noted that the third outcoupling grating 330 may be a two-dimensional grating with a hexagonal lattice structure.

With continued reference to fig. 21-23, the first and second outcoupling gratings 310 and 320 are one-dimensional gratings. In some alternative embodiments of the present application, the first and second outcoupling gratings 310 and 320 are bearing symmetrically arranged with respect to the third outcoupling grating 330.

The third outcoupling grating 330 in this embodiment includes at least two sub-outcoupling gratings, where the junction between two adjacent sub-outcoupling gratings is located in the eye-box of the optical structure 300, and the diffraction efficiency of the sub-outcoupling grating far from the incoupling grating 340 is greater than that of the sub-outcoupling grating near the incoupling grating 340. The overall energy of the light coupled out by the third outcoupling grating 330 may be substantially the same, or it may be understood that the energy of the light coupled out by each sub-outcoupling grating of the third outcoupling grating 330 is substantially the same. And does not affect the intensity of the light coupled out by the third coupling-out grating 330. The following is a detailed description with reference to the drawings.

In an alternative implementation manner of this embodiment, the depth of the grating of the sub-coupling-out grating far from the coupling-in grating 340 is greater than the depth of the grating of the sub-coupling-out grating close to the coupling-in grating 340, so that the diffraction efficiency of the sub-coupling-out grating far from the coupling-in grating 340 can be greater than the diffraction efficiency of the sub-coupling-out grating close to the coupling-in grating 340. I.e., the deeper the grating of the optical structure 300 defined by an alternative embodiment of the present application, the higher its diffraction efficiency.

Referring to fig. 24, fig. 24 is a schematic view of an optical structure according to an embodiment of the present application. Fig. 24 illustrates that the third outcoupling grating 330 includes three sub-outcoupling gratings, namely a first sub-outcoupling grating 331, a second sub-outcoupling grating 332, and a third sub-outcoupling grating 333. At least a portion of each sub-outcoupling grating is located within the eye-box 260. Such as a third outcoupling grating 330, comprises a portion of a first sub-outcoupling grating 231 located on one side of the eye-box, a portion of a second sub-outcoupling grating 332 located on the other side of the eye-box, and a third sub-outcoupling grating 333 located entirely within the eye-box.

The relationship between the first sub-coupling-out grating 331, the second sub-coupling-out grating 332, and the third sub-coupling-out grating 333 can refer to the first sub-coupling-out grating 231, the second sub-coupling-out grating 232, and the third sub-coupling-out grating 233, which are not described herein.

In an alternative embodiment of the present application, the diffraction efficiency of all sub-outcoupling gratings increases equally from one sub-outcoupling grating closest to the incoupling grating 340, such as the first sub-outcoupling grating 331, to one sub-outcoupling grating furthest from the incoupling grating 340, such as the second sub-outcoupling grating 332. It is also understood that the diffraction efficiency of all sub-outcoupled gratings increases in equal proportion along the positive y-axis direction. For example, the diffraction efficiency of the third sub-outcoupling grating 333 is n times that of the first sub-outcoupling grating 331, n being larger than 1. The diffraction efficiency of the second sub-outcoupling grating 332 is n times that of the third sub-outcoupling grating 333. Thereby ensuring that the energy of the light rays coupled out by each sub-diffraction grating is not greatly different.

It should be noted that the third out-coupling grating 330 shown in fig. 24 is only exemplary and does not limit the number of the third out-coupling grating 330. For example, the third outcoupling grating 330 may include two sub-outcoupling gratings, four sub-outcoupling gratings, five sub-outcoupling gratings, and so on. The greater number of sub-outcoupling gratings is not described here.

It should be further noted that, when the number of sub-outcoupling gratings of the third outcoupling grating 330 is greater than three, such as four and five, the boundary between two adjacent sub-outcoupling gratings of all sub-outcoupling gratings of the third outcoupling grating 330 is still located in the eye box of the optical structure 300, and the diffraction efficiency of the sub-outcoupling grating far from the coupling grating 340 is greater than that of the sub-outcoupling grating near the coupling grating 340. The overall energy of the light coupled out by the third outcoupling grating 330 may be made substantially the same, or it may be understood that the energy of the light coupled out by each sub-outcoupling grating of the third outcoupling grating 330 is substantially the same. And does not affect the intensity of the light coupled out by the third coupling-out grating 330.

When the number of sub-outcoupling gratings of the third outcoupling grating 330 is greater than three, such as four, five. At least a portion of all of the sub-gratings of the third outcoupling grating 330 may be located within the eyebox. That is, the third out-coupling grating 330 includes one out-coupling grating partially located on one side of the eye-box, one sub-out-coupling grating partially located on the other side of the eye-box, and two or more sub-out-coupling gratings fully located within the eye-box. The sum of the lengths of all sub-outcoupling gratings completely inside the eyebox along the arrangement direction of all sub-outcoupling gratings of the third outcoupling grating 330 is smaller than the length of any one of the sub-outcoupling gratings partially outside the eyebox along the arrangement direction of all sub-outcoupling gratings of the third outcoupling grating 330. It is also understood that the sum of the lengths of all sub-outcoupling gratings located entirely inside the eyebox in the y-axis direction is smaller than the length of any one of the sub-outcoupling gratings located partly outside the eyebox in the y-axis direction. Reference is specifically made to the above descriptions such as fig. 18 and 19, and the details are not repeated here.

The optical structures 200 and 300 defined in the above embodiments of the present application may be applied to an optical device, which may include a projection light source and any of the above optical structures such as any of the optical structures 200 or any of the optical structures 300. The optical device may be an augmented reality device or a virtual reality device.

The foregoing has outlined the detailed description of the optical structure and optical device provided by the embodiments of the present application, wherein specific examples are provided herein to illustrate the principles and embodiments of the present application, the above examples being provided solely to assist in the understanding of the methods of the present application and the core ideas thereof; meanwhile, those skilled in the art will have variations in the specific embodiments and application scope in light of the ideas of the present application, and the present description should not be construed as limiting the present application in view of the above.

Claims

1. An optical structure, comprising:

a waveguide;

the coupling grating is arranged on the waveguide body;

the first coupling-out grating is arranged on the waveguide body;

the second coupling-out grating is arranged on the waveguide body; and

The first coupling-out grating, the second coupling-out grating and the third coupling-out grating are flush near one side edge of the coupling-in grating, the first coupling-out grating is provided with a plurality of first grids, each first grid is in an asymmetric shape, so that the light efficiency of the first coupling-out grating propagating in a first direction is higher than the light efficiency of the first coupling-out grating propagating in a second direction, the first direction is the direction of the first coupling-out grating towards the second coupling-out grating, and the second direction is opposite to the first direction;

2. The optical structure of claim 1, wherein the third out-coupling grating includes a second side disposed opposite the first side from the first side of the in-coupling grating, the first side being longer along the arrangement direction of the first out-coupling grating, the third out-coupling grating, and the second out-coupling grating than along the arrangement direction of the second side.

3. The optical structure of claim 2, wherein the width of the third out-coupling grating decreases gradually from the first side to the second side, wherein the width of the third out-coupling grating is a length of the third out-coupling grating along the arrangement direction of the first out-coupling grating, the third out-coupling grating, and the second out-coupling grating.

4. The optical structure of claim 3, wherein the third out-coupling grating further comprises a fourth side disposed opposite the third side, the third side connecting one end of the first side and one end of the second side, the fourth side connecting the other end of the first side and the other end of the second side, the third side and fourth side being disposed axisymmetrically with respect to the first side and the second side;

the first coupling-out grating and the second coupling-out grating are axially symmetrically arranged relative to the third coupling-out grating.

5. An optical structure as claimed in any one of claims 1 to 4, wherein the third outcoupling grating is a two-dimensional grating of square lattice structure.

6. The optical structure of claim 5, wherein the first and second outcoupling gratings are one-dimensional gratings.

7. The optical structure of 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 eyebox of the optical structure, the diffraction efficiency of the sub-outcoupling grating further from the incoupling grating being greater than the diffraction efficiency of the sub-outcoupling grating closer to the incoupling grating.

8. The optical structure of claim 7, wherein the third outcoupling grating comprises at least three sub-outcoupling gratings, the at least three sub-outcoupling gratings comprising a first sub-outcoupling grating partially located on one side of the eyebox, a second sub-outcoupling grating partially located on the other side of the eyebox, and at least one sub-outcoupling grating completely located within the eyebox;

the length of the first sub-coupling-out grating along the arrangement direction of all the sub-coupling-out gratings is larger than the sum of the lengths of at least one sub-coupling-out grating positioned in the eye box along the arrangement direction of all the sub-coupling-out gratings;

the length of the second sub-coupling-out grating along the arrangement direction of all the sub-coupling-out gratings is larger than the sum of the lengths of at least one sub-coupling-out grating positioned in the eye box along the arrangement direction of all the sub-coupling-out gratings.

9. The optical structure of claim 8, wherein the sub-outcoupling grating located entirely within the eyebox is any one of one, two, or three, and the diffraction efficiency of all sub-outcoupling gratings increases in equal proportion from one sub-outcoupling grating closest to the incoupling grating to one sub-outcoupling grating furthest from the incoupling grating.

10. The optical structure of claim 8, wherein the first sub-outcoupling grating and the second sub-outcoupling grating are symmetrically disposed with respect to the sub-outcoupling grating that is entirely within the eyebox.

11. An optical device, comprising:

the optical structure of any one of claims 1-10.