CN221303616U - Coupling-out assembly and optical waveguide - Google Patents

Abstract

The application discloses a coupling-out assembly and an optical waveguide, which relate to the technical field of optical display. The coupling-out component and the optical waveguide provided by the application can improve the uniformity of an output image under the condition of ensuring pupil expansion.

Description

Coupling-out assembly and optical waveguide

Technical Field

The application relates to the technical field of optical display, in particular to a coupling-out assembly and an optical waveguide.

Background

Augmented reality (Augmented Reality, AR) is a technology applied in combination with real and virtual images, video, 3D models, the goal of which is to fit the virtual world around the real world and interact on the screen. The AR glasses based on the optical waveguide are one of the AR glasses with the largest application prospect at present. The light waveguide structure is small, the weight is light, the optical function is strong, and the light waveguide structure is a core device for realizing the portable AR glasses. Optical waveguides based on surface relief gratings SRG are currently the dominant choice for AR eyewear optical waveguides. The current scheme paths of the relief grating waveguide mainly comprise a one-dimensional grating-based waveguide scheme and a two-dimensional grating-based waveguide scheme. Based on the one-dimensional grating waveguide scheme, there is an extended area, which occupies a large part of the area, and when the field of view increases, the extended area also increases sharply, so the one-dimensional grating waveguide scheme is limited to the field of view. The two-dimensional grating waveguide is divided into a coupling-in area and a coupling-out area, and the coupling-out area has the functions of extension and coupling-out, so that the eye movement range is greatly increased, and a larger visual field can be realized.

However, under the condition of consistent manufacturing conditions, the coupling-out efficiency of the two-dimensional grating is lower, and if no one-dimensional grating exists in a mixed mode, the overall brightness and uniformity of the emergent image are insufficient, so that the user experience is not facilitated.

Disclosure of utility model

The application aims to provide a coupling-out assembly and an optical waveguide, which can improve the uniformity of an output image under the condition of ensuring pupil expansion.

In one aspect, an embodiment of the present application provides an out-coupling assembly, including a plurality of out-coupling portions arranged in a determinant, where two adjacent rows and two adjacent columns of out-coupling portions are connected, the out-coupling portions correspond to pixels of an output image through a preset rule, the output image is coupled out by the out-coupling assembly, each out-coupling portion is respectively provided with a one-dimensional grating or a two-dimensional grating, and the one-dimensional gratings and the two-dimensional gratings in the plurality of out-coupling portions are arranged according to the preset rule.

As an embodiment, the dimensions of the gratings arranged in adjacent two of the outcoupling portions are different in the direction of the rows or in the direction of the columns of the outcoupling portions.

As an embodiment, the plurality of coupling-out portions form a plurality of concentric patterns from the center to the outer periphery, and the dimensions of the gratings disposed on the coupling-out portions on adjacent two concentric patterns are different in the direction from the center to the outer periphery.

As an implementation manner, the plurality of coupling-out portions are divided into a plurality of coupling-out large areas, and the one-dimensional gratings and the two-dimensional gratings in different coupling-out portions in the coupling-out large areas are arranged according to a preset rule.

As an embodiment, the coupling-out region is divided in the row direction and in the column direction of the determinant.

As an embodiment, the coupling-out large areas are divided in the direction from the center to the outer circumference, so that the plurality of coupling-out large areas are a plurality of concentric rings.

As an implementation manner, each coupling-out part is randomly allocated with a one-dimensional grating or a two-dimensional grating by a computer, and the ratio of the one-dimensional grating to the two-dimensional grating in the coupling-out assembly is 1:1.

As an embodiment, the angle between two gratings in the two-dimensional grating is between 10 ° and 90 °.

As an embodiment, the one-dimensional grating is a surface relief grating or a volume hologram grating, and the two-dimensional grating is a surface relief grating or a volume hologram grating.

Another aspect of the embodiments of the present application provides an optical waveguide, including a coupling-in region and a coupling-out region, where the coupling-out region is provided with the coupling-out component described above.

The beneficial effects of the embodiment of the application include:

The application provides an output assembly, which comprises a plurality of coupling-out parts which are arranged in a row-column mode, wherein the coupling-out parts are connected with the coupling-out parts of two adjacent rows and two adjacent columns, the coupling-out parts correspond to pixel points of an output image through a preset rule, the output image is coupled out by the coupling-out assembly, the coupling-out assembly forms a plurality of pixel groups corresponding to the resolution of human eyes, each pixel group comprises a plurality of coupling-out parts, namely a plurality of coupling-out parts form a pixel group, the pixel group corresponds to the resolution of the human eyes, and the pixel group is the smallest unit which can be identified by the human eyes, each pixel group comprises a one-dimensional grating and a two-dimensional grating, the diffraction efficiency of the one-dimensional grating is higher, the two-dimensional grating is used for expanding the pupil, the coupling-out area is divided into a plurality of coupling-out parts by taking the pixel points as units, and the one-dimensional grating and the two-dimensional grating are contained in each pixel group, so that the pixel group has higher coupling-out efficiency in the same pixel group, namely the pixel group has higher coupling-out uniformity in the most-out area, and higher coupling-out uniformity in the image can be realized in the pixel group, and the image has higher coupling-out uniformity.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a coupling assembly according to an embodiment of the present application;

FIG. 2 is a second schematic diagram of a coupling-out assembly according to an embodiment of the present application;

FIG. 3 is a schematic diagram of an optical waveguide according to an embodiment of the present application;

FIG. 4 is a second schematic diagram of an optical waveguide according to an embodiment of the present application;

FIG. 5 is a third schematic diagram of a coupling-out assembly according to an embodiment of the present application;

FIG. 6 is a third schematic diagram of an optical waveguide according to an embodiment of the present application;

FIG. 7 is a schematic diagram of a coupling-out assembly according to an embodiment of the present application;

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

Icon: 10-an out-coupling assembly; 11-a coupling-out; 111-a one-dimensional grating; 112-a two-dimensional grating; 20-an optical waveguide; 21-a coupling-out region; 22-a coupling-in region; 23-extension area.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. The components of the embodiments of the present application generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the application, as presented in the figures, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

In the description of the present application, it should be noted that, directions or positional relationships indicated by terms such as "center", "vertical", "horizontal", "inner", "outer", etc., are directions or positional relationships based on those shown in the drawings, or those that are conventionally put in place when the product of this application is used, are merely for convenience of describing the present application and simplifying the description, and are not indicative or implying that the apparatus or element to be referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be construed as limiting the present application.

In order to simultaneously consider pupil expansion and coupling-out efficiency, the prior art adopts a scheme of large-area mixed arrangement of the one-dimensional grating and the two-dimensional grating. However, this design presents a significant problem. Due to the difference in physical properties between one-dimensional and two-dimensional gratings, there is a large difference in their outcoupling efficiency. In particular, the outcoupling efficiency of a one-dimensional grating is typically several times higher than that of a two-dimensional grating. This causes a problem: when two gratings are mixed in a large area, due to the difference of coupling efficiency, the generated image has uneven brightness, and the uneven brightness can seriously affect the visual quality of the image, so that the viewing experience of a user is reduced.

The embodiment of the application provides a coupling-out assembly 10, as shown in fig. 1 and 2, which comprises a plurality of coupling-out portions 11 arranged in rows and columns, wherein the coupling-out portions 11 of two adjacent rows and two adjacent columns are connected, the coupling-out portions 11 correspond to pixel points of an output image through a preset rule, the output image is coupled out by the coupling-out assembly 10, a one-dimensional grating 111 or a two-dimensional grating 112 is respectively arranged in each coupling-out portion 11, the coupling-out assembly 10 forms a plurality of pixel groups corresponding to human eye resolution, each pixel group comprises a plurality of coupling-out portions 11, and each pixel group comprises the one-dimensional grating 111 and the two-dimensional grating 112.

The coupling-out assembly 10 provided in the embodiment of the present application is disposed in the coupling-out area 21 of the optical waveguide 20, and is used for coupling out image beams to form an output image, and in the embodiment of the present application, the coupling-out area 21 is divided into a plurality of coupling-out portions 11, and the coupling-out portions 11 correspond to pixels of the output image through a preset rule, and by way of example, the coupling-out portions 11 correspond to the pixels of the output image one by one, so that the size of each coupling-out portion 11 is very small, and a human eye cannot identify one pixel independently. The coupling-out assembly 10 forms a plurality of pixel groups corresponding to resolution of human eyes, that is, the human eyes can identify the pixel groups, the pixel groups comprise a plurality of pixel points, each pixel group comprises a one-dimensional grating 111 and a two-dimensional grating 112, wherein the one-dimensional grating 111 has higher coupling-out efficiency, and the two-dimensional grating 112 can expand the field angle, so that each pixel group has higher coupling-out efficiency and larger field angle. The pixel groups have higher coupling-out efficiency and larger field angle, namely the pupil expansion effect and the higher coupling-out efficiency in the minimum range which can be distinguished by human eyes, so that the uniformity of each pixel group in the output image is higher, and the uniformity of the output image is improved.

It should be noted that, the grating is formed by a group of slits with a pitch of nanometer, and the slits of the one-dimensional grating 111 are arranged along one direction, wherein the arrangement direction is multiple, that is, the grating direction of the one-dimensional grating 111 is multiple, and in the multiple coupling-out portions 11, the grating angles of the one-dimensional grating 111 may be the same or different. Similarly, the angles between the two-dimensional gratings 112 may be the same or different in the plurality of coupling-out portions 11.

It should be further noted that, in order to clearly show the structures of two adjacent coupling-out portions 11, only a portion of the structures of the coupling-out portions 11 are shown in fig. 2, 5 and 7 to indicate the arrangement rule of the one-dimensional grating 111 and the two-dimensional grating 112.

The shape of each coupling-out portion 11 is not limited in this embodiment, and may be, for example, rectangular, circular or other polygonal, and, for example, square as shown in fig. 1, when each coupling-out portion 11 is formed as square, two adjacent coupling-out portions 11 can be seamlessly connected, and the space of the coupling-out area 21 can be fully utilized.

In addition, the coupling-out assembly 10 according to the embodiment of the present application is disposed in the coupling-out region 21 of the optical waveguide 20, where the specific structure of the optical waveguide 20 is not limited to the embodiment of the present application, and may be, for example, a binocular optical waveguide 20 as shown in fig. 3 and 6, or a monocular optical waveguide 20 as shown in fig. 4.

The coupling-out component 10 provided by the application comprises a plurality of coupling-out parts 11 which are arranged in a row-column mode, and the coupling-out parts 11 of two adjacent rows and two adjacent columns are connected, wherein the coupling-out parts 11 are corresponding to pixel points of an output image through a preset rule, the output image is coupled out by the coupling-out component 10, the coupling-out component 10 forms a plurality of pixel groups corresponding to the resolution of human eyes, each pixel group comprises a plurality of coupling-out parts 11, namely the plurality of coupling-out parts 11 form a pixel group, the pixel group corresponds to the resolution of human eyes, the pixel group is the smallest unit which can be identified by human eyes, each pixel group comprises a one-dimensional grating 111 and a two-dimensional grating 112, the diffraction efficiency of the one-dimensional grating 111 is higher, the two-dimensional grating 112 is used for expanding the pupil, the coupling-out area 21 is divided into the plurality of coupling-out parts 11 by taking the pixel points as units, and the plurality of coupling-out parts 11 form a pixel group, and each pixel group comprises the one-dimensional grating 111 and the two-dimensional grating 112, so that the uniform coupling-out efficiency of the coupling-out component can be realized in the pixel groups, and the uniform coupling-out efficiency of the image can be realized in the uniform in the pupil of each pixel group, and the output pupil has the uniform coupling-out efficiency, and the uniform coupling-out effect can be realized in the image in the high output pupil range.

In the embodiment of the application, the coupling-out parts 11 and the pixel points are correspondingly arranged through a preset rule by utilizing the limit of the resolution of human eyes, a pixel group is formed by a plurality of coupling-out parts 11, and in the same pixel group, the non-uniformity generated by mixing the two-dimensional grating 112 and the one-dimensional grating 111 can not be recognized by human eyes. Each pixel group has higher diffraction efficiency, so that the picture between each pixel group is uniform, i.e. the picture seen by human eyes is uniform.

Alternatively, as shown in fig. 1 and 2, the dimensions of the gratings provided by adjacent two of the outcoupling portions 11 are different in the row direction or the column direction of the outcoupling portions 11.

The dimensions of the gratings disposed in the two adjacent coupling-out portions 11 are different along the row direction or the column direction of the coupling-out portions 11, that is, the one-dimensional gratings 111 and the two-dimensional gratings 112 are alternately disposed in the row direction or the column direction, and in each pixel group, the one-dimensional gratings 111 and the two-dimensional gratings 112 are disposed on average, so that uniformity in each pixel group is improved.

It is understood that the gratings include a one-dimensional grating 111 and a two-dimensional grating 112, and that the dimensions of the gratings disposed in the adjacent two coupling-out portions 11 are different means that the one-dimensional grating 111 and the two-dimensional grating 112 are disposed in the adjacent two coupling-out portions 11, respectively.

Specifically, the one-dimensional grating 111 and the two-dimensional grating 112 are alternately arranged in the row direction; the one-dimensional grating 111 and the two-dimensional grating 112 are alternately arranged in the column direction as shown in fig. 1; the one-dimensional grating 111 and the two-dimensional grating 112 may be alternately arranged in both the row direction and the column direction, as shown in fig. 2.

Fig. 3 and fig. 4 are schematic diagrams of the coupling-out assembly 10 of fig. 1 when the coupling-out assembly 20 is applied to the coupling-out assembly 20, where the coupling-out assembly 10 of fig. 3 includes a coupling-in region 22, an extension region 23, and a coupling-out region 21, and the coupling-out assembly 10 is disposed in the coupling-out region 21, and the input image light is coupled into the optical waveguide 20 by the coupling-in region 22, reaches pupil expansion regions on both sides through multiple total reflections in the optical waveguide 20, diffracts at the pupil expansion regions, propagates through total reflections toward the corresponding coupling-out regions while expanding the pupil, and is coupled out by the coupling-out assembly 10 on the coupling-out region 21 to form the output image light after reaching the coupling-out region 21. The monocular of fig. 4 includes a coupling-in region 22 and a coupling-out region 21, the coupling-out assembly 10 being disposed within the coupling-out region 21. The input image light is coupled into the optical waveguide 20 by the coupling-in region 22 and propagates in total reflection in the optical waveguide 20 to the coupling-out region 21, and is coupled out by the coupling-out assembly 10 of the coupling-out region 21 to form output image light.

In one implementation manner of the embodiment of the present application, the plurality of coupling-out portions 11 form a plurality of concentric patterns from the center to the periphery, and the dimensions of the gratings disposed in the coupling-out portions 11 of two adjacent concentric patterns are different in the direction from the center to the periphery.

As shown in fig. 5 and 6, the plurality of coupling-out portions 11 are formed in a plurality of concentric squares from the center to the outer circumference, the coupling-out portion 11 on the outermost square is provided with a two-dimensional grating 112, the coupling-out portion 11 on the square of the second turn from the outside to the inside is provided with a one-dimensional grating 111, the coupling-out portion 11 on the square of the third turn from the outside to the inside is provided with a two-dimensional grating 112, and so on to the center of the coupling-out assembly 10.

Fig. 6 is a schematic diagram of the coupling-out assembly 10 of fig. 5 when the coupling-out assembly 20 is applied to the coupling-out assembly 20, where the coupling-out assembly 20 includes a coupling-in region 22, an expansion region 23, and a coupling-out region 21, the coupling-out assembly 10 is disposed in the coupling-out region 21, the input image light is coupled into the optical waveguide 20 by the coupling-in region 22, reaches pupil expansion regions on both sides through multiple total reflections in the optical waveguide 20, diffracts at the pupil expansion regions, propagates to the corresponding coupling-out regions through total reflections while expanding the pupil, and is coupled out by the coupling-out assembly 10 on the coupling-out region 21 after reaching the coupling-out region 21 to form the output image light.

Optionally, the plurality of coupling-out portions 11 are divided into a plurality of coupling-out large areas, and the one-dimensional gratings 111 and the two-dimensional gratings 112 in different coupling-out portions 11 in the coupling-out large areas are arranged according to a preset rule.

According to the position and effect of each coupling-out large area, the proportion of the one-dimensional grating 111 and the two-dimensional grating 112 in each coupling-out large area is adjusted to further improve the uniformity of the image light output by the coupling-out assembly 10.

In one implementation of the embodiment of the application, the coupling-out large area is divided along the row direction and the column direction of the determinant.

The coupling-out large areas are divided according to the row direction and the column direction of the determinant, so that the coupling-out large areas are arranged in the determinant, a one-dimensional grating and a two-dimensional grating are respectively arranged for each coupling-out large area, the two-dimensional grating and the one-dimensional grating are arranged according to a preset rule, the coupling-out assembly 10 can be adjusted according to actual conditions, and the adaptability of the coupling-out assembly 10 is improved.

Optionally, the out-coupling large areas are divided in a direction from the center to the periphery such that the plurality of out-coupling large areas are a plurality of concentric rings.

In practical applications, the requirements of the center and the outside on diffraction efficiency and field angle are different, and the number of the middle-dimensional gratings 111 and the two-dimensional gratings 112 of each concentric ring can be set according to practical situations, which is an example. More one-dimensional gratings 111 can be arranged in the outer ring, and the output efficiency of the outer side can be improved by arranging more one-dimensional gratings 111 in the outer ring in order to further improve the uniformity of the picture because the coupling-out efficiency at the edge of the coupling-out assembly 10 is lower; the ring near the center is a region where the human eyes directly watch, and more two-dimensional gratings 112 can be arranged, so that the field angle of the center region is larger, namely the picture range is wider, and the experience is improved.

In one implementation manner of the embodiment of the present application, as shown in fig. 7 and 8, each of the coupling-out portions 11 is configured by a computer to randomly allocate one-dimensional gratings 111 or two-dimensional gratings 112, and the ratio of the one-dimensional gratings 111 to the two-dimensional gratings 112 in the coupling-out assembly 10 is 1:1.

Each of the coupling-out sections 11 is randomly assigned a one-dimensional grating 111 and a two-dimensional grating 112 by a computer, and specifically, the computer generates a matrix containing numerals 0 and 1, the matrix corresponding to pixels of the output image, the numeral 0 representing the one-dimensional grating 111 and the numeral 1 representing the two-dimensional grating 112. When the computer allocates 0 and 1 randomly, a certain condition needs to be set, one is that each pixel group must contain two kinds of gratings, and the other is that the duty ratio of the two kinds of gratings meets the certain condition.

When the ratio of the one-dimensional grating 111 to the two-dimensional grating 112 in the coupling-out assembly 10 is 1:1, the uniformity of the light emitted by the coupling-out assembly 10 and a larger field angle are ensured.

Fig. 8 is a schematic diagram of the coupling-out assembly of fig. 7 when applied to a binocular light guide, in which the binocular light guide 20 includes a coupling-in region 22 and a coupling-out region 21, the coupling-out assembly 10 is disposed in the coupling-out region 21, the input image light is coupled into the light guide 20 by the coupling-in region 22, reaches the coupling-out regions 21 on both sides through multiple total reflections in the light guide 20, reaches the coupling-out regions 21, and is coupled out by the coupling-out assembly 10 on the coupling-out regions 21 to form output image light.

Alternatively, the angle between two of the two-dimensional gratings 112 may be between 10-90.

The two-dimensional grating 112 comprises two one-dimensional gratings 111 which are arranged in a crossing way, and the included angle of the grating directions of the two one-dimensional gratings 111 is 10 degrees to 90 degrees. Specifically, the angle between two gratings in the two-dimensional grating 112 is not limited by the implementation of the present application, and may be 90 ° as shown in fig. 1, or 45 ° as shown in fig. 2.

In one implementation of the embodiment of the present application, the one-dimensional grating 111 is a surface relief grating or a volume hologram grating, and the two-dimensional grating 112 is a surface relief grating or a volume hologram grating.

The holographic grating is formed by two beams with specific wave surface shape interfering, forming interference fringes with alternate brightness and darkness on a recording plane, recording the interference fringes by using a holographic recording medium, and processing to obtain the holographic grating. The volume hologram grating is formed by multiple exposure. That is, the volume hologram grating is understood as a plurality of hologram gratings integrated in the same hologram material, and has the advantage of simple preparation method.

The surface relief grating is amplitude modulated, including perpendicular surface relief gratings and oblique surface relief gratings.

The embodiment of the application also discloses a preparation method of the coupling-out assembly 10, wherein the coupling-out assembly 10 is arranged in the coupling-out area 21. The preparation method comprises the following steps:

S10: partitioning the coupling-out area 21 according to pixel points of an image source to form a plurality of coupling-out parts 11 which are arranged in rows and columns;

S20: encoding each coupling-out part 11 according to a preset encoding rule, and determining the dimension of the grating of each coupling-out part 11;

The preset encoding rule may be that the number of the grating of the odd-numbered row is different from that of the grating of the even-numbered row, or that the number of the grating of the odd-numbered column is different from that of the grating of the even-numbered column; alternatively, the dimensions of two adjacent rings of gratings along the center to the periphery may be different; a computer may also be used to randomly assign the one-dimensional grating 111 and the two-dimensional grating 112.

S30: manufacturing a grating template according to the dimension of the grating of each coupling-out part 11;

S40: the coupling-out assembly 10 is formed by imprinting a grating in the coupling-out region 21 using a grating template.

The embodiment of the application also discloses an optical waveguide 20, which comprises a coupling-in region 22 and a coupling-out region 21, wherein the coupling-out region 21 is provided with the coupling-out assembly 10. The optical waveguide 20 comprises the same structure and advantages as the coupling-out assembly 10 of the previous embodiment. The structure and advantages of the coupling-out assembly 10 have been described in detail in the foregoing embodiments, and are not described in detail herein.

The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (10)

1. The coupling-out assembly is characterized by comprising a plurality of coupling-out parts which are arranged in a determinant, wherein the coupling-out parts of two adjacent rows and two adjacent columns are connected, the coupling-out parts correspond to pixel points of an output image through a preset rule, the output image is coupled out by the coupling-out assembly, a one-dimensional grating or a two-dimensional grating is respectively arranged in each coupling-out part, the coupling-out assembly forms a plurality of pixel groups corresponding to the minimum resolution of human eyes, each pixel group comprises a plurality of coupling-out parts, and the pixel groups comprise the one-dimensional grating and the two-dimensional grating.

2. The outcoupling assembly of claim 1, wherein the dimensions of the gratings provided by adjacent two of said outcoupling portions are different in the direction of the rows or in the direction of the columns of said outcoupling portions.

3. The outcoupling assembly of claim 1, wherein a plurality of said outcoupling portions form a plurality of concentric patterns from the center to the outer periphery, and the dimensions of the gratings disposed on the adjacent two concentric patterns are different in the direction from the center to the outer periphery.

4. The out-coupling assembly according to claim 1, wherein the plurality of out-coupling parts are divided into a plurality of out-coupling areas, and the one-dimensional gratings and the two-dimensional gratings in different out-coupling parts in the out-coupling areas are arranged according to a predetermined rule.

5. The outcoupling assembly of claim 4, wherein the outcoupling areas are divided in a row direction and in a column direction of the determinant.

6. The outcoupling assembly of claim 4, wherein the outcoupling large areas are divided in a direction from the center to the outer circumference, such that the plurality of outcoupling large areas are a plurality of concentric rings.

7. The outcoupling assembly of claim 1, wherein each of said outcoupling portions is randomly assigned a one-dimensional grating or a two-dimensional grating by a computer, and the ratio of said one-dimensional grating to said two-dimensional grating in said outcoupling assembly is 1:1.

8. The outcoupling assembly of claim 1, wherein the angle between two of said two-dimensional gratings is between 10 ° and 90 °.

9. The coupling-out assembly of claim 1, wherein the one-dimensional grating is a surface relief grating or a volume holographic grating, and the two-dimensional grating is a surface relief grating or a volume holographic grating.

10. An optical waveguide comprising an in-coupling region and an out-coupling region, the out-coupling region being provided with an out-coupling assembly as claimed in any one of claims 1 to 9.