CN114137649B

CN114137649B - Optical waveguide device for AR device, method for manufacturing the same, and AR device

Info

Publication number: CN114137649B
Application number: CN202011469330.7A
Authority: CN
Inventors: 徐钦锋; 马珂奇; 杜佳玮
Original assignee: Ningbo Sunny Opotech Co Ltd
Current assignee: Ningbo Sunny Opotech Co Ltd
Priority date: 2020-09-04
Filing date: 2020-09-04
Publication date: 2024-06-04
Anticipated expiration: 2040-09-04
Also published as: CN114137649A; CN114137655B; CN114137655A; WO2022048502A1

Abstract

The present invention relates to an optical waveguide device for an AR apparatus, a method of manufacturing the same, and an AR apparatus. The optical waveguide device comprises an optical waveguide substrate, a coupling-in area and a coupling-out area, wherein the coupling-in area is provided with a first grating used for coupling incident light into the optical waveguide substrate, the coupling-out area is provided with a second grating used for coupling out the light from the optical waveguide substrate after two-dimensional expansion, the first grating is provided with a coupling-in grating vector, the second grating is provided with a first coupling-out grating vector and a second coupling-out grating vector which are intersected with each other, the grating unit arrays of the first grating and the second grating are basically parallel and have the same period in one dimension direction, and the first coupling-out grating vector and the second coupling-out grating vector form symmetry relative to the coupling-in grating vector, so that an isosceles triangle is formed by the coupling-in grating vector and the coupling-in grating vector, and the second grating is a two-dimensional surface relief grating and has a three-order cylinder array structure. The invention has the advantages of simple and compact structure, large field angle range, small light energy loss, strong equipment endurance capability and the like.

Description

Optical waveguide device for AR device, method for manufacturing the same, and AR device

Technical Field

The present invention relates to the field of optical imaging technology, and in particular, to an optical waveguide device for an AR device, a method for manufacturing the same, and an AR device.

Background

Optical waveguide sheets are key core components in the new generation of augmented reality technology (Augmented Reality, AR), which combine the principle of total reflection waveguide with a diffraction element to replicate an extended exit pupil in an imaging system, and have become a necessary trend in the development of AR technology due to the advantages of large pupil, small volume, light weight, etc.

The typical optical waveguide technology is to project the image light source emitted by the micro display into the incident grating area of the optical waveguide sheet through the projection lens, and the image light source is captured by the optical waveguide sheet and transmitted to the second grating area by total reflection and then diffracted for turning 90 degrees, meanwhile, the transmitted light continuously goes forward by total reflection along the original direction, and is diffracted by the turning grating each time so as to realize one-dimensional expansion in the first direction. The light that has been turned 90 ° will be totally reflected towards the third grating, the grating lines of which are orthogonal to the incident light, which light can be diffracted out or transmitted at each point of interaction with the third grating, and the transmitted light will continue to be transmitted along this direction by total reflection, the third grating providing a one-dimensional expansion in the second direction, so that the image light source that is diffraction-coupled out to the viewer can achieve a two-dimensional expansion. All three gratings used in such optical waveguides are one-dimensional surface relief gratings.

When two out-coupling gratings are arranged in an overlapping manner, two one-dimensional surface relief gratings may be replaced by a two-dimensional surface relief grating for directly achieving two-dimensional expansion and out-coupling of light. In the prior art, the columnar structure of the two-dimensional surface relief grating is limited to the arrangement mode of an equilateral triangle array, and the arrangement limits the freedom degree of grating design and has smaller horizontal field angle.

In addition, each time an image ray is coupled out by a two-dimensional grating, both outward transmission diffraction orders and inward reflection diffraction orders are produced. Generally, more image light is required to be directed to the user side than to the world side, because image light directed to the world side is not only wasteful in nature, but also causes the surrounding population to view the user's content.

The description of this section is for convenience in understanding the present application and thus should not be taken as having been prior art solely by virtue of its inclusion in this section.

Disclosure of Invention

In view of the above, the present invention provides an optical waveguide device for an AR device, a method of manufacturing the same, and an AR device, which can solve or at least alleviate one or more of the above problems, as well as other problems.

According to a first aspect of the present invention there is provided an optical waveguide device for an AR apparatus comprising an optical waveguide substrate, an incoupling region and an outcoupling region, the incoupling region being provided with a first grating for coupling incident light into the optical waveguide substrate, the outcoupling region being provided with a second grating for two-dimensionally expanding light from the optical waveguide substrate and outcoupling, the first grating having an incoupling grating vector, the second grating having first and second incoupling grating vectors intersecting each other, the respective arrays of grating elements of the first and second gratings being substantially parallel and of the same period in one dimension, the first and second incoupling grating vectors forming a symmetry with respect to the incoupling grating vector and together forming an isosceles triangle with the incoupling grating vector, wherein the second grating is a two-dimensional surface relief grating having a three-order cylinder array structure comprising: a plurality of first columns arranged to form the second grating cell array, each of which protrudes outward from an outer surface of the coupling-out region and has a first height in a direction perpendicular to the outer surface; and a plurality of second columns each disposed on top of a corresponding first column and having a second height in a direction perpendicular to the outer surface, a bottom surface of the second column being contained within a top surface of the first column, a bottom surface area of the second column being smaller than a bottom surface area of the first column.

In the optical waveguide device for an AR apparatus according to the present invention, optionally, the first grating has a first grating cell array periodically arranged in a first dimension direction perpendicular to a grating groove line direction thereof, the second grating has a second grating cell array periodically arranged in the first dimension direction and a second dimension direction perpendicular thereto, and periods of the first grating cell array and the second grating cell array conform to the following relation:

p0=py, and s=k×px

Wherein P0 is a period of the first grating unit array in a first dimension direction, px and Py are periods of the second grating unit array in the first dimension direction and a second dimension direction respectively, s is an offset between two adjacent rows in the second grating unit array in the first dimension direction, and k is a coefficient with a value range of 0.45-0.55.

In the optical waveguide device for an AR apparatus according to the present invention, optionally, the period P0 of the first grating unit array has a size ranging from 250nm to 500nm, and the ratio between the period Py and the period Px of the second grating unit array is 0.7 to 1.2.

In the optical waveguide device for an AR apparatus according to the present invention, optionally, the second grating further has a derivative grating vector, and a ratio between a magnitude of the derivative grating vector and a magnitude of the coupling-in grating vector is 0.45-0.55.

In the optical waveguide device for an AR apparatus according to the present invention, optionally, the cross-sectional shape of the pillars of the third-order pillar array structure includes a circle, an ellipse, a polygon, and any combination thereof.

In the optical waveguide device for an AR device according to the present invention, optionally, the surface of the third-order pillars of the third-order pillar array structure has a gradient of height decreasing in at least three directions, wherein the first direction is a transmission direction of the second grating coupled-in light, the second direction is a transmission direction of the second grating left-turn light, and the third direction is a transmission direction of the second grating right-turn light.

In the optical waveguide device for an AR apparatus according to the present invention, optionally, the second column is provided to be offset with respect to the first column toward a direction in which the first grating is located.

In the optical waveguide device for an AR apparatus according to the present invention, optionally, the bottom surface of the second pillar is tangent with respect to the bottom surface of the first pillar, and the tangent point is located in the offset direction of the second pillar.

In the optical waveguide device for an AR apparatus according to the present invention, optionally, the bottom surface of the second pillar is scaled down in equal proportion at a preset scaling-down rate according to the bottom surface of the first pillar.

In the optical waveguide device for an AR apparatus according to the present invention, the reduction rate may optionally range from 0.45 to 0.65.

In the optical waveguide device for an AR apparatus according to the present invention, optionally, in a two-dimensional plane formed by the first dimension direction and the second dimension direction of the second grating unit array, a projection of the second column in the two-dimensional plane is smaller than a projection of the first column corresponding thereto in the two-dimensional plane in at least three directions.

In the optical waveguide device for an AR apparatus according to the present invention, optionally, wherein the first height ranges from 30nm to 65nm, and the second height has a substantially equivalent height to the first height.

In the optical waveguide device for an AR apparatus according to the present invention, optionally, the second grating cell array is disposed to protrude outward or to be recessed inward from the outer surface of the coupling-out region, and the first grating cell array is disposed to protrude outward or to be recessed inward from the outer surface of the coupling-in region.

In the optical waveguide device for an AR apparatus according to the present invention, optionally, the first grating includes a blazed grating, a tilted grating, and a binary grating.

In the optical waveguide device for an AR apparatus according to the present invention, the optical waveguide substrate may have a thickness of 0.3mm to 2.5mm and a refractive index of 1.4 to 2.2.

Furthermore, according to a second aspect of the present invention, there is also provided an AR device comprising:

one or more optical waveguide devices for an AR device as claimed in any preceding claim; and

And the image projection device is arranged on the light incident side of the optical waveguide device and is used for sending image light to make the image light incident to the coupling-in area of the optical waveguide device.

Further, according to a third aspect of the present invention, there is further provided a manufacturing method of an optical waveguide device for an AR apparatus, the manufacturing method including the steps of:

Providing an optical waveguide substrate;

providing a coupling-in region having a first grating with a coupling-in grating vector and coupling incident light into the optical waveguide substrate; and

Providing an out-coupling region having a second grating with a first out-coupling grating vector and a second out-coupling grating vector and out-coupling light from the optical waveguide substrate after two-dimensional expansion, wherein the array of grating elements of the second grating is substantially parallel and of the same period in one dimension direction as the array of grating elements of the first grating, and the first out-coupling grating vector and the second out-coupling grating vector form a symmetry with respect to the in-coupling grating vector and together with the in-coupling grating vector form an isosceles triangle,

Wherein the second grating is configured as a two-dimensional surface relief grating having a third order cylinder array structure comprising: a plurality of first columns arranged to form the second grating cell array, each of which protrudes outward from an outer surface of the coupling-out region and has a first height in a direction perpendicular to the outer surface; and a plurality of second columns each disposed on top of a corresponding first column and having a second height in a direction perpendicular to the outer surface, a bottom surface of the second column being contained within a top surface of the first column, a bottom surface area of the second column being smaller than a bottom surface area of the first column.

In the manufacturing method of the optical waveguide device for an AR apparatus according to the present invention, optionally, the first grating is configured to have a first grating cell array periodically arranged in a first dimension direction perpendicular to a grating groove line direction thereof, and the second grating is configured to have a second grating cell array periodically arranged in the first dimension direction and a second dimension direction perpendicular thereto, periods of the first grating cell array and the second grating cell array conforming to the following relation:

p0=py, and s=k×px

In the method for manufacturing an optical waveguide device for an AR apparatus according to the present invention, optionally, the period P0 of the first grating unit array has a size ranging from 250nm to 500nm, and the ratio between the period Py and the period Px of the second grating unit array is 0.7 to 1.2.

In the method of manufacturing an optical waveguide device for an AR apparatus according to the present invention, optionally, the second grating further has a derivative grating vector, and a ratio between a magnitude of the derivative grating vector and a magnitude of the coupling-in grating vector is 0.45-0.55.

In the method of manufacturing an optical waveguide device for an AR device according to the present invention, optionally, the cross-sectional shape of the pillars of the third-order pillar array structure includes a circle, an ellipse, a polygon, and any combination thereof.

In the method for manufacturing an optical waveguide device for an AR device according to the present invention, optionally, the surface of the third-order pillars of the third-order pillar array structure has a gradient of height decreasing in at least three directions, wherein the first direction is a transmission direction of the coupling-in light of the second grating, the second direction is a transmission direction of the left-turn light of the second grating, and the third direction is a transmission direction of the right-turn light of the second grating.

By adopting the technical scheme of the invention, the optical waveguide device is easy to realize two-dimensional pupil expansion, is not limited to the arrangement of the equilateral triangle grating array, thereby being beneficial to improving the design freedom of the existing optical waveguide sheet, promoting the product structure to be more compact and light, and being capable of enabling the angle of view to be wider, and enabling the coupled light rays to be basically consistent with the coupled light rays in directions so as to be easy to realize the display of the projection image without basically aberration. In addition, the invention can effectively reduce the light energy loss caused by the diffraction order transmitted to the world side, thereby being beneficial to enhancing the diffraction efficiency of the user side and improving the endurance of the AR equipment. The optical waveguide device and the AR equipment have simple and compact structures, are very suitable for mass production, and have good industrial application value.

Drawings

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and examples, but it should be understood that these drawings are for illustrative purposes only and are not necessarily drawn to scale.

Fig. 1 is a schematic perspective view of an embodiment of an optical waveguide device according to the present invention.

Fig. 2 is a schematic side view of an embodiment of the optical waveguide device shown in fig. 1, wherein the micro projector and human eye are also schematically illustrated.

Fig. 3 is a schematic diagram of a conventional column array in the prior art.

Fig. 4 is a schematic structural view of an example of a columnar grating cell array of the second grating in the embodiment of the optical waveguide device shown in fig. 1.

Fig. 5 shows the coupling-in grating vector G0, the coupling-out grating vectors G1 and G2 corresponding to the coupling-in grating element H0, the coupling-out grating elements H1 and H2, respectively, in the embodiment of the optical waveguide device shown in fig. 1, these grating vectors G0, G1 and G2 now forming isosceles triangles.

Fig. 6 shows the in-coupling grating vector G0 and the out-coupling grating vector G3 corresponding to the in-coupling grating element H0 and the out-coupling grating element H3, respectively, in this optical waveguide device embodiment.

Fig. 7 is a schematic view of an optical transmission path of light in the embodiment of the optical waveguide device.

Fig. 8 is a front view of the optical transmission path shown in fig. 7 in the xoy plane.

Fig. 9 shows that the first horizontal field angle Fx1 from the optical signal transmitted by the first grating is provided by the standard grating element H1.

Fig. 10 shows that the second horizontal angle of view Fx2 from the optical signal transmitted by the first grating is provided by the standard grating element H2.

Fig. 11 shows a corresponding graph of the field of view supported by the second grating at three different two-dimensional period ratios in an embodiment of the optical waveguide device.

Fig. 12 shows a K-vector diagram of an embodiment of an optical waveguide device having a large field of view.

Fig. 13 shows three different second order cell array examples.

Fig. 14 shows the case where an outward transmission diffraction order T1 and an inward reflection diffraction order R1 are simultaneously generated each time an image light is coupled out by the second grating in the optical waveguide device embodiment.

Fig. 15 shows a second grating in this embodiment of the optical waveguide device using a second order columnar cell array, wherein the bottom surface of the column exhibits a convex hexagon symmetrical about the y-axis.

Fig. 16 shows the coupling-out diffraction efficiency curves of the s-polarized light, the p-polarized light transmitted in the second grating using the second hexagonal cell array, respectively transmitted diffraction order T1, reflected diffraction order R1, as a function of the incident angle β, based on the fourier mode simulation.

Fig. 17 shows a corresponding structure of an example of third-order grating units for the second grating, each having a different bottom surface cylinder.

Fig. 18 is a different view of the third order hexagonal cylinder cell structure of example (c) shown in fig. 17.

Fig. 19 shows the arrangement of the third-order hexagonal cylinder structure of fig. 18 into a two-dimensional array of grating elements coupled out of the grating.

Fig. 20 shows the coupling-out diffraction efficiency curves of the two-dimensional grating cell array shown in fig. 18 for s-polarized light and p-polarized light transmitted in the coupling-out grating, respectively, for the transmission diffraction order T1 and the reflection diffraction order R1 as a function of the incident angle β.

Fig. 21 to 24 show the diffraction efficiency of the s-polarized light and the p-polarized light as a function of the reduction ratio v and the first height d1, respectively, when the total third-order cylinder height d=80 nm in the two-dimensional grating cell array-coupled grating shown in fig. 18, respectively.

Fig. 25 to 28 show the diffraction efficiency of the s-polarized light and the p-polarized light as a function of the reduction ratio v and the first height d1, respectively, when the total height d=100 nm of the third-order columns in the two-dimensional grating cell array-coupled grating shown in fig. 18, respectively.

Fig. 29 to 32 show the diffraction efficiency of the respective transmission diffraction orders T1 and reflection diffraction orders R1 of s-polarized light and p-polarized light as a function of the reduction ratio v and the first height d1, respectively, when the total height d=120 nm of the third-order columns in the two-dimensional grating cell array coupling-out grating shown in fig. 18.

Fig. 33 is a flowchart of an embodiment of a method of manufacturing an optical waveguide device according to the present invention.

Detailed Description

First, it should be noted that the steps, constructions, features, advantages, and the like of the optical waveguide device for an AR apparatus and the manufacturing method thereof, and the AR apparatus according to the present invention will be described below by way of example, but all descriptions should not be construed to limit the present invention in any way. In this document, the technical terms "first," "second," and "substantially" are used for distinguishing purposes only and not to represent a sequential order, relative importance, etc., and the technical term "substantially" is intended to include insubstantial errors associated with a particular amount of measurement, such as may include ranges of ± 8%, ±5% or ± 2% of a given value, the technical terms "upper," "lower," "right," "left," "horizontal," "vertical," and derivatives thereof should be related to the orientation in the various drawings, and it should be understood that the invention may take on a variety of alternative orientations.

Furthermore, to any single feature described or implied in the embodiments herein, or any single feature shown or implied in the figures, the invention still allows any combination or deletion of such features (or equivalents thereof) without any technical barrier, thereby covering further embodiments according to the invention. In addition, for the sake of brevity, identical or similar parts and features may be indicated in the same drawing only at one or several places, and general matters which have been well known to those skilled in the art are not repeated herein.

Referring to fig. 1, 2 and 7, there is shown in schematic form the basic construction and operation of an embodiment of an optical waveguide device according to the present invention, which is well suited for application in AR equipment. As shown, in this embodiment, the optical waveguide device is configured to be substantially sheet-shaped and comprises an optical waveguide substrate 1, an in-coupling region 2 and an out-coupling region 3. The optical waveguide substrate 1 is transparent to visible light and may generally have two opposing optical planes. In this embodiment, the optical waveguide substrate 1 will transmit the image light entering the inside thereof by total reflection, and its thickness may be optionally set to 0.3mm to 2.5mm and the refractive index to 1.4 to 2.2. Generally, light and thin, high refractive index optical waveguide substrates are preferred for use in the present invention.

As shown in fig. 1, a coupling-in region 2 may be arranged at one end of the optical waveguide substrate 1, and a first grating (or called a coupling-in grating) may be provided in the coupling-in region 2, so as to be used to couple received incident light (e.g., image light from the micro projector 4 shown in fig. 2) into the optical waveguide substrate 1, thereby achieving total reflection transmission within the optical waveguide substrate 1. In this embodiment, the first grating may be a one-dimensional surface relief grating and the grating grooves may be arranged parallel to the x-axis, as shown for example in fig. 1. Alternatively, in order to achieve as high a coupling efficiency as possible, it is preferable to use a blazed grating, a slanted grating, a binary grating, or the like for the first grating.

For the out-coupling region 3, it may be arranged at the other end of the optical waveguide substrate 1, and a second grating (or called out-coupling grating) may be arranged in the out-coupling region 3 for two-dimensionally expanding the light entering the optical waveguide substrate 1 via the in-coupling region 2 and for coupling it out of the optical waveguide substrate 1 in the z-axis direction for diffracting into the human eye 5. In this embodiment, the second grating may be a two-dimensional surface relief grating for cooperation with the first grating described above, as will be described in more detail below.

A prior art general cylinder array structure having a horizontal period Px in the x-axis direction, a vertical period Py in the y-axis direction, and a row offset s is schematically illustrated in fig. 3. As for the row offset s, it is defined as an offset in the x-axis direction of the odd and even rows of the array structure, for example, shown as row offset s=0 in this fig. 3.

The present inventors have found, after extensive research analysis, that in order to enable effective two-dimensional expansion and coupling-out of image light, when the line shift amount s in the second grating is set to 0.45-0.55 times its horizontal period Px and its vertical period Py is set to be equal to the period P0 of the first grating, a quite good technical effect will be obtained, and it is most effective when the line shift amount s is set to half the horizontal period Px, the column array structure at this time being shown very clearly in fig. 4. For the post-offset column array structure in the second grating, it can be regarded as the result of superposition of the two inclined periodic structures h1 and h2, the included angle θ exists between the grating line and the y-axis, and the vertical periodic structure in the y-axis direction is destroyed due to offset, however, the first row and the second row can be regarded as a new periodic structure h3, and the period is twice as long as Py. In practical applications, the above grating period P0 may optionally be set small enough to promote that the diffraction order corresponding to the incident light can better satisfy the total reflection condition and be captured by the optical waveguide substrate 1, and for example, the value range of the period P0 may be set to 250nm-500nm.

Fig. 5 and 6 each show a respective grating vector that can be set for the respective periodic structure of the first grating and the second grating, wherein fig. 5 shows the coupling-in grating vector G0 and the coupling-out standard grating vector G1 and G2 respectively corresponding to the coupling-in grating element H0 and the coupling-out grating element H1 and H2 on the optical waveguide device, and fig. 6 shows the coupling-in grating vector G0 and the coupling-out derivative grating vector G3 respectively corresponding to the coupling-in grating element H0 and the coupling-out grating element H3 on the optical waveguide device. In particular, these grating vectors of the first and second gratings may lie in a plane in which the grating lines lie and may extend in a direction perpendicular to the grating line direction, the magnitude of the grating vectors may be given for example by the expression g=2pi/d, where d is the period of the grating (i.e. the pitch between adjacent grating grooves). Although the in-coupling and out-coupling gratings are spatially separated from each other, these grating vectors may be superimposed and connected together due to their spatially translationally invariant nature.

In the embodiment of fig. 1, a micro projector 3 is used to project image light onto the optical waveguide device, and the grating diffraction turning effect to which the image light is subjected each time can be represented by a vector superposition of a grating vector and an optical wave vector. When the optical waveguide device finishes image transmission, achromatic imaging conditions need to be met, namely, after image light rays with different wavelengths and different angles are finally coupled out through diffusion transmission, the direction of emergent light and the direction of incident light need to be consistent, and the emergent light wave vector needs to be consistent with the incident light wave vector. Thus, the diffraction turning effects of the several gratings need to cancel each other out in the working plane of the optical waveguide device, which is shown by the sum of the grating vectors being equal to zero, or substantially zero, which may for example be below a certain threshold value set according to the application requirements as a decision criterion.

If the achromatic imaging conditions described above are required to be fully satisfied, then the following relationship is defined: p0=py, and s=px/2. This is a sufficient condition for zero sum of raster vector superposition to be described in detail below. It can be appreciated that the angle between the y-axis and the grating line of the coupling-out grating elements H1, H2 is θ, and therefore the angle between the x-axis and the coupling-out standard grating vectors G1, G2 is also θ, and the following relationship exists:

For the magnitude of the out-coupling standard grating vectors G1 and G2, the calculation can be performed according to the following relation:

Further, the superimposed vector coupling out both standard grating vectors G1 and G2 can be expressed as:

thus, the coupling-in grating vector G0 can be expressed as:

Thus, as shown in fig. 5, an isosceles triangle can be enclosed by the above grating vectors G0, G1, G2 without being limited to an equilateral triangle, and no additional resultant vector is generated, while the achromatic imaging condition is satisfied. Of course, in some embodiments, it is also conceivable to set the row offset s to k times the period Px (k+.0.5 but in the range of 0.45-0.55), and although achromatic imaging is not optimal at this time, a better effect can be obtained, so that various application needs can be satisfied sufficiently and flexibly.

The present invention enables light outcoupling to be achieved with substantially no angular or chromatic shift by employing such grating arrangements and combinations as suggested above. Since the two coupling-out standard grating vectors G1 and G2 of the second grating cross each other and are symmetrically arranged with respect to the coupling-in grating vector G0 of the first grating so that they can be formed together into an isosceles triangle, such a grating array arrangement not limited to the isosceles triangle is very advantageous in terms of improving the design freedom, compactness, etc. of the optical waveguide device. The second grating is symmetrical for a two-dimensional expansion of the incident light, and its two out-coupling standard vectors can be output from the optical waveguide device after two diffractions of the incident light, and its output direction coincides with the input direction, which is independent of wavelength, so that a color display can be conveniently realized.

When a two-dimensional surface relief grating is used for the second grating, the diffraction properties possessed by the two-dimensional relief grating cannot be considered merely as a superposition of the coupling-out grating elements H1 and H2. In fact, when light from the first grating enters the second grating via the optical waveguide substrate 1, the derivative grating H3, which is periodically arranged along the y-axis direction, will also couple the light beam out of the optical waveguide device. As a preferred scenario, this part of the outgoing beam may also be required to meet the achromatic condition. The grating vector G3 of the derivative grating H3 can be expressed as:

It can be seen that the effect is best when the magnitude of the derived grating vector G3 is half the magnitude of the coupling-in grating vector G0, although a better effect can be achieved when the ratio of the magnitudes is set in the range of 0.45-0.55. When the second-order diffraction grating vector corresponding to the derivative grating H3 is twice the derivative grating vector G3, the sum of the superposition of its second-order diffraction grating vector and the coupling-in grating vector is equal to zero, as shown in fig. 6, and the grating vector returns to the origin after being superimposed by the two derivative grating vectors G3, thereby satisfying the achromatic imaging condition.

Fig. 7 is a schematic view of an optical transmission path of light in the optical waveguide device embodiment, and fig. 8 is a front view of the optical transmission path shown in fig. 7 in the xoy plane. As shown in fig. 7 and 8, when the image light from the first grating is incident on the second grating, a plurality of different diffractions will be simultaneously generated by the action of the different grating elements contained in the latter, wherein the light is received at point a of the second grating and will simultaneously undergo four diffractions.

Specifically, after the coupling-in light ray O is received at point a, it first couples the derivatized grating element H3 directly out of the optical waveguide device in-2 order a1, along the z-axis, toward the eye of the observer.

The light received at point a will then be diffracted into the zero order a2, which is a continuation of the direction of propagation of the incident light. The zero order light a2 is allocated most of the light energy, which can go on to point B and subsequent action points on the same path, and at these points a diffraction action similar to point a is further produced.

Third, the light received at point a also interacts with standard grating element H1 to produce first order lateral diffracted light a3, which is diffracted in a direction at an angle θ to the x-axis (coincident with angle θ in fig. 4), and continues to interact with standard grating element H2 in the two-dimensional grating at point C, producing coupled-out diffraction order C1. Since c1 undergoes the diffraction actions of the three grating elements H0, H1, H2 in sequence, so that the corresponding superimposed grating vectors G0, G1, G2 produce a counteracting action, the angular and chromatic properties of the diffraction order c1 will remain consistent with the coupling-in light O. The light incident at point C will also interact with the standard grating element H1 such that the interaction with the standard grating element H1 at point a is mutually conjugated, a diffraction order C3 towards point F is generated corresponding to the standard grating vector G1 superimposed with two opposite directions, and the transmission direction of C3 remains consistent with the coupling-in ray O at point a. Ray c3 will further produce a diffraction effect similar to point a along the-y axis at point F and subsequent points of action on the same path. Furthermore, zero order light C2 incident at point C will continue to produce a diffraction effect similar to point C further at point E and subsequent action points on the same path, in a direction at an angle θ to the x-axis.

Fourth, the light received at point a also interacts with standard grating element H2 to produce first order lateral diffracted light a4 and is transmitted toward point D. Since both standard grating elements H2 and H1 are symmetrical with respect to the y-axis, the subsequent diffractive transmission path of a4 is also symmetrical with a 3. This path creates diffusion and coupling out towards the left side of the optical waveguide device. After a series of diffraction and transmission, light can finally be coupled out simultaneously on both the left and right sides of the coupling-out region of the optical waveguide device, so that a complete continuous image can be observed by the observer's eyes at any position in the region.

It should be noted that the number of optical paths discussed is limited in the above exemplary description for the sake of brevity, and that the optical transmission paths shown in fig. 7 and 8 are described by way of example with light coupled in along the z-axis, in fact similar optical paths are equally feasible when the coupled-in light is incident at an angle to the z-axis. However, if the angle between the coupled-in light and the yoz plane is too large, the lateral diffracted light a3 or a4 will be lost due to the inability to satisfy the effective total reflection transmission, and the remaining standard grating element corresponding to the lateral diffracted light retains the ability to effectively diffract and transmit the coupled-in light of the partial angle.

Referring again to fig. 9 and 10, the first and second horizontal angles Fx1 and Fx2, respectively, are provided by standard grating elements H1 and H2, respectively, from the optical signal transmitted by the first grating. As shown in fig. 9, the standard grating element H1 may provide a first horizontal angle of view Fx1 from the optical signal transmitted by the first grating, where the optical signal received at the first grating will be transmitted as diffracted light a3 onto another standard grating element H2 comprised by the second grating, which will then act as an output diffractive optical element, coupling light from the optical waveguide device to the viewer. As further shown in fig. 10, the standard grating element H2 may provide a second horizontal angle of view Fx2 from the optical signal transmitted by the first grating, the optical signal received at the first grating will be transmitted as diffracted light a4 onto another standard grating element H1 comprised by the second grating, which will then act as an output diffractive optical element, coupling light from the optical waveguide device to the viewer.

Although the first horizontal angle of view Fx1 and the second horizontal angle of view Fx2 partially overlap, they contain angles relative to each other that the other party does not contain. Obviously, if the field angle of the non-overlapping portion is larger, the total field angle Fx supported by the second grating will also be larger. In fig. 9 and 10, fy is the angle of view of the image light transmitted along the y-axis, which will be limited by the refractive index of the waveguide material. The present invention has found that if the vertical period Py and the horizontal period Px of the second grating are both set to different ratios, this will have a significant effect on the supported horizontal total field angle Fx.

For example, in one embodiment, the optical waveguide substrate 1 may be configured as an optical flat glass having a refractive index of 1.7 and a thickness of 1mm, the first grating period P0 is 340nm, the horizontal period Px of the second grating is 392.6nm, the vertical period Py is 340nm, the two-dimensional period ratio w=py/px=0.866, the horizontal offset s is 196.3nm, and blue light of 460nm is used as the coupling-in light source. In fig. 11, the area surrounded by the dot curve and the y-axis shown in the figure defines the half-field of view of the optical waveguide device.

For another example, in another embodiment, the optical waveguide substrate 1 may be configured as an optical flat glass having a refractive index of 1.7 and a thickness of 1mm, the first grating period P0 is 340nm, the horizontal period Px of the second grating is 360nm, the vertical period Py is 340nm, the two-dimensional period ratio w=py/px=0.944, the horizontal offset s is 180nm, and blue light of 460nm is used as the coupling-in light source. In fig. 11, the area surrounded by the y-axis of the star curve shown in the figure defines the half-field of view of the optical waveguide device.

For another example, in still another embodiment, the optical waveguide substrate 1 may be configured as an optical flat glass having a refractive index of 1.7 and a thickness of 1mm, the first grating period P0 is 340nm, the horizontal period Px of the second grating is 340nm, the vertical period Py is 340nm, the two-dimensional period ratio w=py/px=1, the horizontal offset s is 170nm, and blue light of 460nm is used as the coupling-in light source. In fig. 11, the area surrounded by the y-axis of the four-point curve shown in the figure defines the half-field of view range of the optical waveguide device.

It will be appreciated that since the field of view of the optical waveguide device is symmetrical about the y-axis, half of the actual horizontal field of view of the optical waveguide device is shown in fig. 11. When the angle of view of the coupled-in light exceeds the range enclosed by the curve and the y-axis shown in fig. 11, the coupled-out light either may go away or additional coupled-out diffraction orders may be generated, which will affect the quality of the coupled-out image. As can be seen from fig. 11, as the two-dimensional period ratio w of the second grating gradually increases, the supported field of view range hardly changes in the vertical direction, while gradually expanding in the horizontal direction. The horizontal angle of view when the two-dimensional period ratio w is equal to 1 increases by about 65% compared to the horizontal angle of view when w is equal to 0.866. It is therefore believed that with further increases in the two-dimensional period ratio w, the field of view range in the horizontal direction can be further amplified. However, if the two-dimensional period ratio w is relatively too large, then the adjacent exit pupils of the optical waveguide device will have too large a spacing, thereby compromising the continuous distribution of the exit pupil light energy and compromising the uniformity of the coupled-out image of the optical waveguide device; in contrast, if the two-dimensional period ratio w is relatively too small, it may be difficult to support a large angle of view. Therefore, according to the results of the studies of the present inventors, it is considered to be advantageous to set the two-dimensional period ratio w optionally in the range of 0.7 to 1.2.

With continued reference to fig. 12, a K-vector diagram of an example of an optical waveguide device having a large field of view is shown. In fig. 12, a circle O1 represents a lower limit of a transmission angle of the optical waveguide device limited by a minimum total reflection angle, a circle O2 represents an upper limit of a transmission angle of the optical waveguide device determined by a transmission mode, an annular shadow region represents an angular space region in which an effective transmission view angle is possible, F1 represents a transmission view corresponding to a projection view corresponding to collimated light projected by the projection light machine, P1 represents a transmission view F1 after diffraction is generated by the coupling-in grating element H0 to become a transmission view F4, P2 represents a transmission view F3 after diffraction is generated by the standard grating element H1 to become a part of the transmission view F4, P4 represents a transmission view F3 after diffraction is generated by the standard grating element H2 to be coupled out of the optical waveguide device and be separated from the effective transmission region, P3 represents a transmission view F4 after diffraction is generated by the standard grating element H2 to become a transmission view F2, and P5 represents a transmission view F2 after diffraction is generated by the standard grating element H1 to be coupled out of the optical waveguide device and separated from the effective transmission region. After leaving the optical waveguide arrangement, the partial fields of view on both sides will again combine to form a complete field of view F1, which is then received by the eyes of the observer.

A few examples of second order cell arrays that may be used for the second grating are shown by way of example only in fig. 13. For example, a second-order rectangular cell array shown in example (a), a concave polygon cell array shown in example (b), a second-order convex polygon cell array (including an internal angle of more than 180 °) shown in example (c) may be used in the drawings, but the present invention also allows cell arrays of other arbitrary shapes such as an elliptical cell array, or even cell arrays of some combination patterns. In addition, it should be noted that these cell array structures may be cylindrical in shape, which is intended herein to have a broad meaning, for example, to cover numerous relatively simple or rather complex configurations such as pyramids, prisms, hemispheres, oblique prisms, etc., with which only the energy distribution of the different diffraction orders of a two-dimensional grating can be changed without changing the optical transmission path. In addition, it should be noted that these cell array structures may be protruded from the surface of the substrate material, or may be recessed from the surface of the substrate material, and a coating layer may be provided above the cell array structures or may be an air environment, but forming a refractive index difference on both sides of the cell array structures is a necessary condition for diffraction. In light of the above teachings of the present invention, those skilled in the art will appreciate that there are in fact a number of suitable structural shapes for the second grating in the optical waveguide device.

As shown in fig. 14, when the light guide device is mounted on the AR apparatus, when the image light from the light guide device is coupled out toward the eyes of the observer, each coupled-out image light will simultaneously produce an outward transmission diffraction order T1 (also commonly referred to as the world side) and an inward reflection diffraction order R1 (also commonly referred to as the user side). In general, it is desirable to direct more image light to the user side than to the world side, as image light directed to the world side is not only wasteful in nature, but also can make other people around the observer see the output content unnecessarily. It would therefore be advantageous to obtain a relatively small first order transmitted diffracted light and a relatively large first order reflected diffracted light.

The present invention has found that for a second order columnar cell array out-coupling grating, the diffraction efficiencies of its first order reflection R1 and first order transmission T1 are substantially similar. In some embodiments, the second grating unit array may be selected from, for example, a convex hexagon with a bottom surface of the cylinder symmetrical about the y-axis as shown in fig. 15. As an example, the second grating unit array may be set to have a horizontal period px=335 nm, a vertical period py=335 nm, a groove depth (column height) =73 nm, and a horizontal offset s=167.5 nm, and then the prismatic dotted line around the convex hexagon as shown in fig. 15 defines a unit structure where the column is located, where a line segment c0d0=px, a line segment a0b0=2×py, four sides A1E1, A1E2, B1E3, and B1E4 are parallel to the sides of the prism, two sides E1E3 and E2E4 are parallel to the y axis, a length ratio u of the line segment A1B1 to the line segment A0B 0=0.8 (i.e., a filling factor), and a length ratio u of the line segment E1E3 to the line segment A1B 1=0.65. In this example, 460nm blue light may be used as the incoupling light source, and a corresponding optical waveguide substrate with a refractive index of 1.7 may be used. The incident light ray is transmitted in the xoy plane along the direction A0 to C0 (or A0 to D0) in the figure, and the incident light ray may form an incident angle β with the z-axis.

With continued reference to fig. 16, a coupling-out diffraction efficiency curve of s-polarized light and p-polarized light transmitted in the second grating using the second hexagonal cell array, obtained based on the simulation of the fourier mode method, is further shown in the figure, where the respective transmission diffraction order T1 and reflection diffraction order R1 of the s-polarized light vary with the incident angle β. As can be seen from fig. 16, R1 and T1 are equivalent in value at the same angle in any polarization state, so that the second-order columnar cell array coupled grating wastes a lot of light energy on the world side, which is very unfavorable for continuous voyage for a generally compact and light consumer AR system. In this regard, the present invention has found and proposed an effective means capable of solving the above problems.

By way of illustration, for example, in some embodiments, the second grating in the optical waveguide device may optionally be arranged in a higher order columnar array structure, e.g., of third order or more. Research analysis according to the invention shows that the light energy loss caused by diffraction orders transmitted to the world side can be effectively reduced by adopting the high-order columnar array structure.

In general, if the order of the columnar array grating is higher, its blaze characteristic is more remarkable, but in consideration of the processing easiness, cost and the like, as an alternative, it may be considered to configure the second grating as a third-order columnar array structure including a plurality of first posts 11 and a plurality of second posts 12 protruding from the waveguide surface, the posts being arranged in a two-dimensional periodic array, and each of the first posts 11 having a first height d1 in a direction perpendicular to the waveguide surface, each of the second posts 12 protruding from the upper surface of the first posts 11 and having a second height d2, there is no particular limitation in relation to the relationship between the second height d2 and the first height d1 in the scheme according to the present invention, for example, it is generally considered to be arranged to have substantially equivalent heights, i.e., as long as they are made approximately equivalent in the height dimension order, it is not necessary that the heights differ too much. The bottom surface of the second cylinder 12 is also generally smaller than the bottom surface of the first cylinder 11, so that its lower surface will be contained within the upper surface of the first cylinder 11. The second cylinder 12 may be offset with respect to the first cylinder 11 in the direction of the coupling-in grating. In the alternative, the second cylinder 12 may be configured such that the bottom surface thereof is reduced in equal proportion to the bottom surface of the first cylinder 11, and in addition, the bottom surface of the second cylinder 12 may be made tangential to the bottom surface of the first cylinder 11, with the tangential point being located in the above-described offset direction.

In fig. 17, several third order grating units using different bottom surface columns are shown, respectively, which can be used for the second grating. As shown in the figure, the surfaces of these three-step cylinder examples (a), (B) and (C) may have a gradient with a height decreasing in at least three directions, wherein the first direction is the transmission direction of the light coupled into the second grating (see the direction A0 to B0 in fig. 15), the second direction is the transmission direction of the turning light on the left side of the second grating (see the direction A0 to D0 in fig. 15), and the third direction is the transmission direction of the turning light on the right side of the second grating (see the direction A0 to C0 in fig. 15).

A different view of the third order cylinder example (c) shown in fig. 17 is further provided in fig. 18. As shown in the figure, the bottom surface of the first column 11 is substantially identical to the hexagon shown in fig. 15, the first height d1=50 nm, the filling factor u=0.8, the bottom surface of the second column 12 is a hexagon with an equal proportion reduction ratio v=50%, and the second height d2=50 nm is offset in the +y axis direction, so that there is a gradient of a first height decrease along the direction D1 in the xoy plane (the direction of A0 to B0 in fig. 15), for example, as shown in a side view (a), and there is a gradient of a second height decrease along the direction D2 in the xoy plane (the direction of A0 to C0 in fig. 15), as shown in a side view (B), and there is a gradient of a third height decrease along the direction D3 in the xoy plane (the direction of A0 to D0 in fig. 15), for example, as shown in a side view (C), and therefore, a similar gradient to the gradient is formed in a plurality of directions, so that the diffraction efficiency of the blazed side can be effectively reduced, and the diffraction efficiency of the blazed side can be effectively enhanced, and the diffraction device can be improved.

With continued reference to fig. 19, there is schematically illustrated the arrangement of the third order column structure illustrated in fig. 18 into a two-dimensional array of grating elements coupled out of the grating. As an example, the grating cell array may be set to have a horizontal period px=335 nm, a vertical period py=335 nm, and a horizontal offset s=167.5 nm, i.e., an arrangement consistent with the second-order columnar cell array shown in fig. 15, for comparison.

In fig. 20, there is shown the coupling-out diffraction efficiency curve of the respective transmission diffraction order T1, reflection diffraction order R1 as a function of the incident angle β for s-polarized light, p-polarized light transmitted in the above-described third-order grating cell array, in which the incident light uses 460nm blue light, which is transmitted in the xoy plane in the A0 to C0 (or A0 to D0) direction as shown in fig. 15. As shown in fig. 20, the diffraction efficiency of the reflection order R1 facing the user side can reach 2-3 times the transmission order T1 on the world side in the same polarization state. Therefore, by adopting the scheme according to the invention, the reflection level R1 can be greatly enhanced, so that the diffraction efficiency of the user side is improved, and the transmission level T1 is effectively restrained.

As described above, according to the scheme of the invention, the design optimization of the high-order two-dimensional coupling-out grating can be realized, so that the diffraction efficiency of the user side can be further enhanced, and the good effect of weakening the diffraction efficiency of the world side can be realized. Fig. 21 to 32 each show a case of performing optimization simulation for diffraction efficiency of the second grating example using the above-described third-order grating cell array.

Specifically, fig. 21 to 24 show the diffraction efficiency of the s-polarized light and the p-polarized light as a function of the reduction ratio v and the first height d1 of the first cylinder, respectively, when the total height d=d1+d2=80 nm of the third-order cylinder in this second grating example.

Fig. 25 to 28 show the diffraction efficiency of the respective transmission diffraction orders T1 and reflection diffraction orders R1 of s-polarized light and p-polarized light as a function of the reduction ratio v and the first height d1, respectively, when the third-order cylinder total height d=100 nm in this second grating example.

Fig. 29 to 32 show the diffraction efficiency of the respective transmission diffraction orders T1 and reflection diffraction orders R1 of s-polarized light and p-polarized light as a function of the reduction ratio v and the first height d1, respectively, when the third-order cylinder total height d=120 nm in this second grating example.

As shown in these fig. 21 to 32 above, in the area indicated by the ellipse in the drawing, the diffraction efficiency on the user side is strong, while the diffraction efficiency on the world side is low. In addition, it can be found that the effect of the total height d of the different third-order columns on the area where the ellipse is located is not significant in a certain range under different polarization states, and the reduction ratio v in the area is approximately in the range of 0.45-0.65, and the first height d1 is approximately in the range of 30-65 nm.

According to an aspect of the present invention, there is also provided an AR apparatus on which one or more of the above-discussed optical waveguide devices according to the present invention may be disposed, and the image-capturing device may be disposed on the light-incident side of the optical waveguide device so as to transmit image light thereto to be incident on the coupling-in region of the optical waveguide device. Due to the adoption of the corresponding arrangement and combination of the first grating and the second grating, the AR device can provide light coupling output under the condition of basically no angle or chromaticity shift, the two-dimensional pupil expansion is easy to realize, the design freedom degree is higher, the field angle range is larger, the transmission diffraction light can be effectively reduced to improve the energy efficiency, and the cruising ability and the product competitiveness of the AR device are improved.

In addition, according to another aspect of the present invention, there is also provided a manufacturing method of an optical waveguide device for an AR device, which is easy to mass-produce and process, and has high productivity, thus having strong industrial application value. As an exemplary illustration, referring to fig. 33, the general steps involved in manufacturing the optical waveguide device of the present invention are presented in this embodiment.

Specifically, first in step S11, an optical waveguide substrate may be provided;

Then, a coupling-in region with a first grating may be provided in step S12, for example, the coupling-in region may be provided at one end of the optical waveguide substrate, the first grating having a coupling-in grating vector and causing incident light to be coupled into the optical waveguide substrate;

In step S13, an out-coupling region having a second grating may be provided, for example, the out-coupling region may be provided at the other end of the optical waveguide substrate, the second grating having a first out-coupling grating vector and a second out-coupling grating vector intersecting each other, and the light from the optical waveguide substrate is two-dimensionally expanded and then coupled out, wherein the grating cell array of the second grating is substantially parallel to the grating cell array of the first grating in one dimension direction and the periods of the two are the same, the first out-coupling grating vector and the second out-coupling grating vector have substantially equal magnitudes, and they are symmetrically provided with respect to the in-coupling grating vector, so that an isosceles triangle may be formed by the first out-coupling grating vector, the second out-coupling grating vector, and the in-coupling grating vector together.

As described above, since the above description of the optical waveguide device for an AR apparatus and the example of the AR apparatus of the present invention has been described in detail with respect to the structural configuration, composition, arrangement, characteristics, etc. of the optical waveguide device, the detailed description of the foregoing corresponding parts may be directly referred to in the method of the present invention, and will not be repeated here.

The optical waveguide device for an AR device and the manufacturing method thereof and the AR device according to the present invention are explained in detail above by way of example only, which are provided for illustrating the principle of the present invention and its embodiments, and not by way of limitation, and various modifications and improvements can be made by those skilled in the art without departing from the spirit and scope of the present invention. For example, although the optical waveguide device in the AR apparatus generally adopts a monolithic sheet-like structure, the optical waveguide device in the present invention allows for any suitable structural form, for example, it may be allowed to locally form a bump or the like shape in some cases. Accordingly, all equivalent arrangements should be considered to be within the scope of the present invention and as defined in the claims.

Claims

1. An optical waveguide device for an AR device comprising an optical waveguide substrate, an incoupling region and an outcoupling region, the incoupling region being provided with a first grating for coupling incident light into the optical waveguide substrate, the outcoupling region being provided with a second grating for two-dimensionally expanding light from the optical waveguide substrate and outcoupling, the first grating having an incoupling grating vector, the second grating having a first incoupling grating vector and a second incoupling grating vector intersecting each other, characterized in that the respective arrays of grating elements of the first and second gratings are substantially parallel in one dimension and of the same period, the first and second incoupling grating vectors having substantially equal magnitudes to form together with the incoupling grating vector an isosceles triangle,

Wherein the second grating is a two-dimensional surface relief grating having a three-order cylinder array structure, the cylinders being arranged in a two-dimensional periodic array comprising:

A plurality of first pillars arranged to form a second grating cell array, each of which protrudes outward from an outer surface of the waveguide of the coupling-out region and has a first height in a direction perpendicular to the outer surface; and

A plurality of second columns each of which is arranged on top of a corresponding first column and has a second height in a direction perpendicular to the outer surface, a bottom surface of the second column being contained within a top surface of the first column, a bottom surface area of the second column being smaller than a bottom surface area of the first column.

2. The optical waveguide apparatus for an AR device according to claim 1, wherein the first grating has a first grating cell array periodically arranged in a first dimension direction perpendicular to a grating groove line direction thereof, the second grating has a second grating cell array periodically arranged in the first dimension direction and a second dimension direction perpendicular thereto, and periods of the first and second grating cell arrays conform to the following relation:

p0=py, and s=k×px

Wherein P0 is a period of the first grating unit array in the first dimension direction, px and Py are periods of the second grating unit array in the first dimension direction and the second dimension direction, s is an offset between two adjacent rows in the second grating unit array in the first dimension direction, and k is a coefficient with a value ranging from 0.45 to 0.55.

3. The optical waveguide device for AR equipment according to claim 2, wherein the period P0 of the first grating unit array has a size ranging from 250nm to 500nm, and the ratio between the period Py and the period Px of the second grating unit array is 0.7 to 1.2.

4. The optical waveguide apparatus for an AR device of claim 1, wherein the second grating further has a derived grating vector, the ratio between the magnitude of the derived grating vector and the magnitude of the coupled-in grating vector being 0.45-0.55.

5. The optical waveguide apparatus for AR device of claim 1, wherein the cross-sectional shape of the pillars of the third-order pillar array structure comprises a circle, an ellipse, a polygon, and any combination thereof.

6. The optical waveguide device for AR device according to claim 1, wherein the surface of the third-order pillars of the third-order pillar array structure has a gradient of height decrease in at least three directions, wherein the first direction is a transmission direction of the second grating coupled-in light, the second direction is a transmission direction of the second grating left-turn light, and the third direction is a transmission direction of the second grating right-turn light.

7. The optical waveguide apparatus for an AR device according to claim 1, wherein the second post is disposed to be offset with respect to the first post toward a direction in which the first grating is located.

8. The optical waveguide apparatus for an AR device of claim 7, wherein the bottom surface of the second post is tangential with respect to the bottom surface of the first post, and the point of tangency is located in the direction of bias of the second post.

9. The optical waveguide device for AR equipment according to claim 1, 7 or 8, wherein the bottom surface of the second pillar is scaled down in equal proportion to the bottom surface of the first pillar at a preset scaling down rate.

10. The optical waveguide apparatus for an AR device according to claim 9, wherein the reduction ratio ranges from 0.45 to 0.65.

11. The optical waveguide apparatus for an AR device according to claim 9, wherein, in a two-dimensional plane composed of the first dimension direction and the second dimension direction of the second grating unit array, the projection of the second column in the two-dimensional plane is smaller than the projection of the first column corresponding thereto in the two-dimensional plane in at least three directions.

12. The optical waveguide apparatus for an AR device of claim 1, 7 or 8, wherein the first height ranges from 30nm to 65nm and the second height has a substantially equivalent height to the first height.

13. The optical waveguide apparatus for an AR device according to claim 2 or 3, wherein the second grating cell array is disposed to protrude outward from an outer surface of the coupling-out region, and the first grating cell array is disposed to protrude outward or to be recessed inward from an outer surface of the coupling-in region.

14. The optical waveguide apparatus for an AR device of any of claims 1-8, wherein the first grating comprises a blazed grating, a tilted grating, and a binary grating.

15. The optical waveguide device for AR equipment according to any one of claims 1-8, wherein the optical waveguide substrate has a thickness of 0.3mm-2.5mm and a refractive index of 1.4-2.2.

16. An AR device, the AR device comprising:

one or more optical waveguide devices for an AR apparatus as claimed in any one of claims 1-15; and

17. A method of manufacturing an optical waveguide device for an AR apparatus according to any one of claims 1 to 15, comprising the steps of:

Providing an optical waveguide substrate;

Providing an out-coupling region having a second grating with a first out-coupling grating vector and a second out-coupling grating vector intersecting each other and out-coupling light from the optical waveguide substrate after two-dimensional expansion, wherein the array of grating elements of the second grating is substantially parallel and of the same period in one dimension direction as the array of grating elements of the first grating, the first out-coupling grating vector and the second out-coupling grating vector having substantially equal magnitudes and forming together with the in-coupling grating vector an isosceles triangle,

Wherein the second grating is configured as a two-dimensional surface relief grating having a three-order cylinder array structure, the cylinders being arranged in a two-dimensional periodic array comprising:

18. The manufacturing method of the optical waveguide device for AR equipment according to claim 17, wherein the first grating is configured to have a first grating cell array periodically arranged in a first dimension direction perpendicular to a grating groove line direction thereof, and the second grating is configured to have a second grating cell array periodically arranged in the first dimension direction and a second dimension direction perpendicular thereto, periods of the first grating cell array and the second grating cell array conforming to the following relation:

p0=py, and s=k×px

19. The method of manufacturing an optical waveguide device for an AR device according to claim 18, wherein the period P0 of the first grating unit array has a size ranging from 250nm to 500nm, and the ratio between the period Py and the period Px of the second grating unit array is 0.7 to 1.2.

20. The method of manufacturing an optical waveguide device for an AR device according to claim 17, wherein the second grating further has a derivative grating vector, the ratio between the magnitude of the derivative grating vector and the magnitude of the coupling-in grating vector being 0.45-0.55.

21. The method of manufacturing an optical waveguide device for an AR device according to any one of claims 17-20, wherein the cross-sectional shape of the pillars of the third-order pillar array structure includes a circle, an ellipse, a polygon, and any combination thereof.

22. The method for fabricating an optical waveguide device for an AR device according to claim 21, wherein the surface of the third-order pillars of the third-order pillar array structure has a gradient of height decrease in at least three directions, wherein the first direction is a transmission direction of the second grating coupled-in light, the second direction is a transmission direction of the second grating left-turn light, and the third direction is a transmission direction of the second grating right-turn light.