阅读说明：本技术 光波导系统和近眼显示器 (Optical waveguide system and near-eye display ) 是由 高一峰 熊羚鹤 孙理斌 汪杰 陈远 于 2021-08-25 设计创作，主要内容包括：本发明提供了一种光波导系统和近眼显示器。光波导系统包括：光波导片；耦入光栅,耦入光栅设置在光波导片的一侧表面上,耦入光栅为一维光栅,耦入光栅用于将外部微投光机所发出的光耦入到光波导片内；转折光栅,转折光栅设置在光波导片上且与耦入光栅位于同一侧表面或不同侧表面,转折光栅为二维光栅,转折光栅用于接收耦入光栅的光；耦出光栅,耦出光栅设置在光波导片的另一侧表面上,转折光栅和耦出光栅在光波导片上的投影至少部分重合,耦出光栅为一维光栅,耦出光栅用于接收转折光栅和耦入光栅的光并将光耦出光波导片。本发明解决了现有技术中的光波导系统存在成像效果差的问题。(The invention provides an optical waveguide system and a near-eye display. An optical waveguide system comprising: an optical waveguide sheet; the coupling grating is arranged on one side surface of the optical waveguide sheet, is a one-dimensional grating and is used for coupling light emitted by an external micro light-projecting machine into the optical waveguide sheet; the turning grating is arranged on the optical waveguide sheet and is positioned on the same side surface or different side surfaces with the coupling grating, the turning grating is a two-dimensional grating, and the turning grating is used for receiving light of the coupling grating; and the coupling-out grating is arranged on the other side surface of the optical waveguide sheet, the projections of the turning grating and the coupling-out grating on the optical waveguide sheet are at least partially overlapped, the coupling-out grating is a one-dimensional grating, and the coupling-out grating is used for receiving the light of the turning grating and the coupling-in grating and coupling the light out of the optical waveguide sheet. The invention solves the problem of poor imaging effect of the optical waveguide system in the prior art.)

1. An optical waveguide system, comprising:

an optical waveguide sheet (10);

the light guide plate comprises an incoupling grating (20), wherein the incoupling grating (20) is arranged on one side surface of the light guide plate (10), the incoupling grating (20) is a one-dimensional grating, and the incoupling grating (20) is used for coupling light emitted by an external micro-projector (50) into the light guide plate (10);

the turning grating (30) is arranged on the optical waveguide sheet (10) and is positioned on the same side surface or different side surfaces with the coupling-in grating (20), the turning grating (30) is a two-dimensional grating, and the turning grating (30) is used for receiving the light of the coupling-in grating (20);

the optical waveguide chip comprises a coupling-out grating (40), wherein the coupling-out grating (40) is arranged on the surface of the other side of the optical waveguide chip (10), the turning grating (30) and the coupling-out grating (40) are at least partially overlapped in projection on the optical waveguide chip (10), the coupling-out grating (40) is a one-dimensional grating, and the coupling-out grating (40) is used for receiving light of the turning grating (30) and the coupling-in grating (20) and coupling out the light of the optical waveguide chip (10).

2. The optical waveguide system of claim 1, wherein the coupling-in grating (20) is plural, the plural coupling-in gratings (20) are located at one side of the turning grating (30), and the plural coupling-in gratings (20) are arranged along a straight line at intervals.

3. The optical waveguide system according to claim 2, wherein the number of the optical waveguide sheets (10) is one or more, when the number of the optical waveguide sheets (10) is plural, the plural optical waveguide sheets (10) are stacked, the incoupling grating (20), the turning grating (30) and the outcoupling grating (40) are correspondingly disposed on each optical waveguide sheet (10), and projections of the incoupling grating (20) on each optical waveguide sheet (10) on the adjacent optical waveguide sheets (10) are overlapped or not overlapped.

4. The optical waveguide system according to claim 2, wherein the optical waveguide sheet (10) further comprises a functional area grating (60), the functional area grating (60) is disposed between the incoupling grating (20) and the turning grating (30), the functional area grating (60) is a one-dimensional grating, and the functional area grating (60) is configured to deflect and transmit the light incoupling grating (20) into the turning grating (30).

5. The optical waveguide system of claim 1,

the one-dimensional grating is one of a blazed grating, an inclined grating, a rectangular grating, a double-ridge grating and a one-dimensional multilayer grating; and/or

The two-dimensional grating is one of a square grating, a rectangular grating, a parallelogram grating, a rhombus grating and a two-dimensional multi-layer grating.

6. The optical waveguide system of claim 1,

the duty cycle of the incoupling grating (20) is greater than or equal to 30% and less than or equal to 80%; and/or

When the incoupling grating (20) is a one-dimensional multilayer grating, the number of layers of the one-dimensional multilayer grating is more than or equal to 1 layer and less than or equal to 10 layers; and/or

The height of the incoupling grating (20) is greater than or equal to 50 nanometers and less than or equal to 500 nanometers; and/or

The period of the incoupling grating (20) is greater than or equal to 300nm and less than or equal to 600 nm.

7. The optical waveguide system of claim 1,

the duty ratio of the turning grating (30) is more than or equal to 30% and less than or equal to 80%; and/or

When the turning grating (30) is a two-dimensional multilayer grating, the number of layers of the two-dimensional multilayer grating is more than or equal to 1 layer and less than or equal to 10 layers; and/or

The height of the turning grating (30) is more than or equal to 30 nanometers and less than or equal to 300 nanometers; and/or

The period of the turning grating (30) is more than or equal to 300 nanometers and less than or equal to 600 nanometers.

8. The optical waveguide system of claim 1,

the duty cycle of the outcoupling grating (40) is greater than or equal to 30% and less than or equal to 80%; and/or

When the coupling-out grating (40) is a one-dimensional multilayer grating, the number of layers of the one-dimensional multilayer grating is more than or equal to 1 layer and less than or equal to 10 layers; and/or

The height of the coupling-out grating (40) is greater than or equal to 30 nanometers and less than or equal to 300 nanometers; and/or

The period of the outcoupling grating (40) is equal to or greater than 300nm and equal to or less than 600 nm.

9. The optical waveguide system of claim 1,

the optical waveguide sheet (10) is made of glass or optical crystal, the glass is high-refractive-index glass, and the optical crystal is a high-refractive optical crystal; and/or

The refractive index of the optical waveguide sheet (10) is 1.7 or more and 2.3 or less; and/or

The thickness of the optical waveguide sheet (10) is not less than 400 μm and not more than 1 mm.

10. A near-eye display, comprising:

a plurality of micro-projectors (50), wherein one or more micro-projectors (50) are provided;

the optical waveguide system of any one of claims 1 to 9, the micro-projector (50) emitting image light into the optical waveguide system, the optical waveguide system optically coupling out the image into a human eye.

Technical Field

The invention relates to the technical field of diffractive optical imaging equipment, in particular to an optical waveguide system and a near-eye display.

Background

With the continuous development and innovation of science and technology, Virtual Reality (VR), Augmented Reality (AR), and Mixed Reality (MR) have gradually come into the middle of people's lives, wherein in the aspect of AR augmented reality, optical waveguide technology is an indispensable step, and it adopts a flat optical waveguide sheet with diffraction gratings to transmit and expand pupil of image light emitted from a micro-projector to human eyes, so that a wearer observes that the micro-projector projects a virtual image superimposed on the real world while seeing the real world.

The above-mentioned display technologies generally include a micro-projector providing image information in monochrome or color and an optical waveguide system responsible for expanding the pupil of the image information of the micro-projector to the human eye. The design combination mode of the micro-projector and the optical waveguide system determines the final product form, but the current products have partial limitations, and the biggest problem is that the display effect is not ideal, which is caused by the loss of light intensity energy caused by the transmission of light in the optical waveguide sheet and the uneven efficiency of coupled light caused by the characteristics of the diffraction grating. Such non-uniformity may affect image display, resulting in poor imaging observed by human eyes.

That is, the optical waveguide system in the related art has a problem of poor imaging effect.

Disclosure of Invention

The invention mainly aims to provide an optical waveguide system and a near-eye display to solve the problem that the optical waveguide system in the prior art is poor in imaging effect.

In order to achieve the above object, according to one aspect of the present invention, there is provided an optical waveguide system comprising: an optical waveguide sheet; the coupling grating is arranged on one side surface of the optical waveguide sheet, is a one-dimensional grating and is used for coupling light emitted by an external micro light-projecting machine into the optical waveguide sheet; the turning grating is arranged on the optical waveguide sheet and is positioned on the same side surface or different side surfaces with the coupling grating, the turning grating is a two-dimensional grating, and the turning grating is used for receiving light of the coupling grating; and the coupling-out grating is arranged on the other side surface of the optical waveguide sheet, the projections of the turning grating and the coupling-out grating on the optical waveguide sheet are at least partially overlapped, the coupling-out grating is a one-dimensional grating, and the coupling-out grating is used for receiving the light of the turning grating and the coupling-in grating and coupling the light out of the optical waveguide sheet.

Furthermore, the coupled gratings are multiple, the coupled gratings are located at one side of the turning grating, and the coupled gratings are arranged along a straight line at intervals.

Furthermore, the number of the optical waveguide sheets is one or more, when the number of the optical waveguide sheets is multiple, the optical waveguide sheets are stacked, each optical waveguide sheet is correspondingly provided with an incoupling grating, a turning grating and an outcoupling grating, and the projections of the incoupling gratings on the optical waveguide sheets on the adjacent optical waveguide sheets are overlapped or not overlapped.

Furthermore, the optical waveguide sheet further comprises a functional area grating, the functional area grating is arranged between the coupling-in grating and the turning grating, the functional area grating is a one-dimensional grating, and the functional area grating is used for deflecting and transmitting light coupled into the grating so as to enter the turning grating.

Further, the one-dimensional grating is one of a blazed grating, an inclined grating, a rectangular grating, a double-ridge grating and a one-dimensional multilayer grating; and/or the two-dimensional grating is one of a square grating, a rectangular grating, a parallelogram grating, a rhombus grating and a two-dimensional multi-layer grating.

Further, the duty cycle of the coupled-in grating is greater than or equal to 30% and less than or equal to 80%; and/or when the coupling-in grating is a one-dimensional multilayer grating, the number of layers of the one-dimensional multilayer grating is more than or equal to 1 layer and less than or equal to 10 layers; and/or the height of the incoupling grating is greater than or equal to 50 nanometers and less than or equal to 500 nanometers; and/or the period of the incoupling grating is equal to or greater than 300nm and equal to or less than 600 nm.

Furthermore, the duty ratio of the turning grating is more than or equal to 30% and less than or equal to 80%; and/or when the turning grating is a two-dimensional multilayer grating, the number of layers of the two-dimensional multilayer grating is more than or equal to 1 layer and less than or equal to 10 layers; and/or the height of the turning grating is more than or equal to 30 nanometers and less than or equal to 300 nanometers; and/or the period of the turning grating is more than or equal to 300 nanometers and less than or equal to 600 nanometers.

Further, the duty cycle of the out-coupling grating is greater than or equal to 30% and less than or equal to 80%; and/or when the coupled-out grating is a one-dimensional multilayer grating, the number of layers of the one-dimensional multilayer grating is more than or equal to 1 layer and less than or equal to 10 layers; and/or the height of the out-coupling grating is greater than or equal to 30 nanometers and less than or equal to 300 nanometers; and/or the period of the out-coupling grating is equal to or greater than 300 nanometers and equal to or less than 600 nanometers.

Furthermore, the material of the optical waveguide sheet is glass or optical crystal, the glass is high-refractive index glass, and the optical crystal is high-refractive optical crystal; and/or the refractive index of the optical waveguide sheet is 1.7 or more and 2.3 or less; and/or the thickness of the optical waveguide sheet is 400 μm or more and 1 mm or less.

According to another aspect of the present invention, there is provided a near-eye display including: one or more micro-projection machines; in the optical waveguide system, the micro projector emits image light to the optical waveguide system, and the optical waveguide system optically couples the image light out to human eyes.

The optical waveguide system comprises an optical waveguide sheet, an in-coupling grating, a turning grating and an out-coupling grating, wherein the in-coupling grating is arranged on one side surface of the optical waveguide sheet, the in-coupling grating is a one-dimensional grating, and the in-coupling grating is used for coupling light emitted by an external micro-projector into the optical waveguide sheet; the turning grating is arranged on the optical waveguide sheet and is positioned on the same side surface or different side surfaces with the coupling grating, the turning grating is a two-dimensional grating, and the turning grating is used for receiving light coupled into the grating; the coupling grating is arranged on the other side surface of the optical waveguide sheet, the projections of the turning grating and the coupling grating on the optical waveguide sheet are at least partially overlapped, the coupling grating is a one-dimensional grating, and the coupling grating is used for receiving the light of the turning grating and the coupling grating and coupling the light out of the optical waveguide sheet.

By arranging the optical waveguide sheet, the optical waveguide sheet provides arrangement positions for the coupling-in grating, the turning grating and the coupling-out grating, the use reliability of the coupling-in grating, the turning grating and the coupling-out grating is improved, the transmission uniformity of light in the optical waveguide sheet is ensured, and the uniform imaging of an optical waveguide system is ensured. The coupling-in grating is a one-dimensional grating, so that the coupling-in grating can couple most of light emitted by the external micro-projector into the optical waveguide sheet, and diffract the light into different angles and different orders for transmission, thereby ensuring the transmission uniformity of the light in the optical waveguide sheet and the coupling-in efficiency of the coupling-in grating. The turning grating is arranged on the optical waveguide sheet and is positioned on the same side surface or different side surfaces of the optical waveguide sheet with the coupling grating, the turning grating is a two-dimensional grating, so that the turning grating can receive most of light coupled into the grating, the light in the optical waveguide sheet can be transmitted in one-dimensional or two-dimensional directions, the light is transmitted along two specific directions, the information of the micro-projector is transmitted in a pupil expanding manner, and the pupil expanding and light homogenizing effects of the turning grating are ensured. The light coupling grating is arranged on the other side surface of the optical waveguide sheet, is a one-dimensional grating and is used for receiving the light of the turning grating and the light coupling grating and efficiently coupling the light out of the optical waveguide sheet so as to uniformly and efficiently couple the information of the micro-projector to human eyes. The projection of the turning grating and the projection of the coupling grating on the optical waveguide sheet are at least partially overlapped, so that the distance from the turning grating to the coupling grating for transmitting light is shortened, the loss of light intensity energy is reduced, the coupling efficiency is increased, the light coupled out to human eyes is more uniform, the uniformity of the coupled light is ensured, the image observed by a user is clearer and more uniform, and the imaging effect is improved.

In addition, the projections of the turning grating and the coupling-out grating on the optical waveguide sheet are at least partially overlapped, so that the occupied area of the turning grating and the coupling-out grating on the optical waveguide sheet can be effectively reduced, and the miniaturization of the optical waveguide system is ensured. The optical waveguide structure of the application can obtain uniform display images by using smaller optical waveguide sheets, and the display uniformity is improved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 shows a schematic structural diagram of an optical waveguide system of an alternative embodiment of the present invention;

FIG. 2 is a schematic view of another angle of the optical waveguide system of FIG. 1;

FIG. 3 shows a schematic of the structure of a near-eye display of the present invention;

FIG. 4 shows a schematic structural diagram of an optical waveguide system according to another embodiment of the present invention;

FIG. 5 shows a schematic structural diagram of an optical waveguide system according to another embodiment of the present invention;

fig. 6 shows a schematic structural view of an optical waveguide system according to another embodiment of the present invention.

Wherein the figures include the following reference numerals:

10. an optical waveguide sheet; 20. coupling in a grating; 30. turning the grating; 40. coupling out the grating; 50. a micro-projector; 60. and (4) grating the functional area.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

It is noted that, unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

In the present invention, unless specified to the contrary, use of the terms of orientation such as "upper, lower, top, bottom" or the like, generally refer to the orientation as shown in the drawings, or to the component itself in a vertical, perpendicular, or gravitational orientation; likewise, for ease of understanding and description, "inner and outer" refer to the inner and outer relative to the profile of the components themselves, but the above directional words are not intended to limit the invention.

The invention provides an optical waveguide system and a near-eye display, aiming at solving the problem that an optical waveguide system in the prior art is poor in imaging effect.

As shown in fig. 1 to 6, the optical waveguide system includes an optical waveguide sheet 10, an incoupling grating 20, a turning grating 30 and an outcoupling grating 40, the incoupling grating 20 is disposed on one side surface of the optical waveguide sheet 10, the incoupling grating 20 is a one-dimensional grating, and the incoupling grating 20 is used for coupling light emitted by an external micro-light projector 50 into the optical waveguide sheet 10; the turning grating 30 is disposed on the optical waveguide sheet 10 and located on the same side surface or different side surfaces of the coupling grating 20, the turning grating 30 is a two-dimensional grating, and the turning grating 30 is used for receiving the light coupled into the coupling grating 20; the coupling-out grating 40 is disposed on the other side surface of the optical waveguide sheet 10, the projections of the turning grating 30 and the coupling-out grating 40 on the optical waveguide sheet 10 are at least partially overlapped, the coupling-out grating 40 is a one-dimensional grating, and the coupling-out grating 40 is used for receiving the light of the turning grating 30 and the coupling-in grating 20 and coupling the light out of the optical waveguide sheet 10 to human eyes.

By arranging the optical waveguide sheet 10, the optical waveguide sheet 10 provides arrangement positions for the incoupling grating 20, the turning grating 30 and the outcoupling grating 40, so that the use reliability of the incoupling grating 20, the turning grating 30 and the outcoupling grating 40 is improved, the uniformity of light transmission in the optical waveguide sheet 10 is ensured, and the uniform imaging of the optical waveguide system is ensured. The incoupling grating 20 is a one-dimensional grating, so that the incoupling grating 20 can couple most of the light emitted by the external micro-light projector 50 into the optical waveguide sheet 10, so that the incoupling grating 20 diffracts the light into different angles and different orders for transmission, thereby ensuring the uniformity of light transmission in the optical waveguide sheet 10 and the incoupling efficiency of the incoupling grating 20. The turning grating 30 is disposed on the optical waveguide sheet 10 and located on the same side surface as the coupling grating 20, and the turning grating 30 is a two-dimensional grating, so that the turning grating 30 can receive most of the light coupled into the coupling grating 20, and can transmit the light in the optical waveguide sheet 10 in one or two-dimensional directions, so as to transmit and amplify the light in two specific directions, and perform pupil-expanding transmission on the information of the micro-light projector 50, so as to ensure the pupil-expanding and light-homogenizing effects of the turning grating 30. The coupling-out grating 40 is disposed on the other side surface of the optical waveguide sheet 10, the coupling-out grating 40 is a one-dimensional grating, and the coupling-out grating 40 is used for receiving the light of the turning grating 30 and the coupling-in grating 20 and efficiently coupling the light out of the optical waveguide sheet 10, so as to uniformly and efficiently couple out the information of the micro-projector 50 to the human eye. The projection of the turning grating 30 and the coupling grating 40 on the optical waveguide sheet 10 is at least partially overlapped, so that the distance from the turning grating 30 to the coupling grating 40 is shortened, the loss of light intensity energy is reduced, the coupling efficiency is increased, the light coupled out to human eyes is more uniform, the uniformity of the coupled light is ensured, the image observed by a user is clearer and more uniform, and the imaging effect is improved.

In addition, the projections of the turning grating 30 and the coupling-out grating 40 on the optical waveguide sheet 10 are at least partially overlapped, so that the arrangement can effectively reduce the occupied area of the turning grating 30 and the coupling-out grating 40 on the optical waveguide sheet 10, and ensure the miniaturization of the optical waveguide system. The optical waveguide structure of the present application can obtain uniform display images by using a smaller optical waveguide sheet 10, and display uniformity is improved.

In the embodiment not shown in the figures, the turning grating 30 is disposed on the optical waveguide sheet 10 and is located on a different side surface from the coupling grating 20, which can be selected according to the actual situation.

In the embodiment shown in fig. 1, the turning grating 30 and the coupling-out grating 40 are respectively disposed on different surfaces of the optical waveguide sheet 10, and the projections of the turning grating 30 and the coupling-out grating 40 on the optical waveguide sheet 10 are completely corresponding and mostly coincident. In the embodiment shown in fig. 4, the projections of the turning grating 30 and the coupling-out grating 40 on the optical waveguide sheet 10 may not completely correspond to each other, and as shown in the figure, the projections of the turning grating 30 and the coupling-out grating 40 on the optical waveguide sheet 10 are only partially overlapped. Of course, the position relationship and the projection overlapping area of the turning grating 30 and the coupling grating 40 can be adjusted according to the actual situation.

As shown in fig. 1, the coupling grating 20 is a one-dimensional grating, the turning grating 30 is a two-dimensional grating, the coupling grating 40 is a one-dimensional grating, the coupling grating 20 and the turning grating 30 are on the same side surface of the optical waveguide sheet 10, the coupling grating 40 is on the back of the turning grating 30, light reaches the turning grating 30 through the coupling grating 20, passes through the turning grating 30 to transmit the pupil expanding to the coupling grating 40, and the coupling grating 40 couples out light to human eyes. The arrangement makes the turning grating 30 play a role of pupil expanding and light homogenizing, the turning grating 30 in the figure is a square grating, the included angle of the grating lines of the square grating is 90 degrees, so that the turning grating 30 can perform two-dimensional pupil expanding on light, the light efficiency is divided and then reaches the coupling-out grating 40, the coupling-out grating 40 is placed on the back of the turning grating 30, the light which is diffracted to the position of the turning grating 30 is coupled out, and the light transmitted to the coupling-out grating 40 by the turning grating 30 is enabled to be coupled out to human eyes as much as possible. The specific parameters of the coupling-out grating 40 and the turning grating 30 can be set according to the requirements, and the heights or duty ratios in different regions are different, so that the uniformity of the coupled-out light intensity can meet the specific requirements through adjustment. Meanwhile, the arrangement can effectively reduce the size of the optical waveguide sheet 10, so that the optical waveguide sheet is better suitable for being used on a conventional spectacle lens, and the scheme shown in fig. 4 is a modification of the scheme shown in fig. 1, so that the design of the spectacle lens is more in line with the human engineering.

Note that, the arrows in fig. 1 to 4 are all light transmission directions.

As shown in fig. 3, a schematic structural diagram of the near-eye display of the present application is shown. It can be seen that the micro-projector 50 is disposed corresponding to the incoupling grating 20.

As shown in fig. 5, since some micro-projectors 50 cannot perform color display alone, and a plurality of single-color light-projectors are required to be combined to display color, a plurality of incoupling gratings 20 are designed on the light guide sheet 10 corresponding to the plurality of micro-projectors 50, and a three-color RGB light-projector separation scheme shown in the figure is proposed, and two additional incoupling gratings 20 are added on the light guide sheet 10 to perform light transmission of two additional micro-projectors 50 based on the scheme in fig. 1, since the three incoupling gratings 20 in fig. 5 are arranged along the light transmission direction, the three incoupling gratings 20 cannot be disposed on the same light guide sheet 10 to avoid crosstalk between the three incoupling gratings 20, and the three incoupling gratings 20 are disposed on the three light guide sheets 10, that is, each light guide sheet 10 has one incoupling grating 20, one turning grating 30 and one outcoupling grating 40. The turning grating 30 and the coupling-out grating 40 on each optical waveguide sheet 10 are located at the same position, and only the coupling-in grating 20 is located at a different position, and the principle of light transmission on each optical waveguide sheet 10 in fig. 5 is the same as that in fig. 1.

Specifically, the number of the coupling-in gratings 20 is plural, the coupling-in gratings 20 are located at one side of the turning grating 30, and the coupling-in gratings 20 are arranged along a straight line at intervals, for example, the number of the coupling-in gratings 20 may be three, three coupling-in gratings 20 are arranged laterally as shown in fig. 5, or three coupling-in gratings 20 are arranged longitudinally as shown in fig. 6, the arrangement shown in fig. 6 corresponds to one or more optical waveguide sheets 10, that is, three coupling-in gratings 20 may be disposed on one optical waveguide sheet 10, or three coupling-in gratings 20 are disposed on three optical waveguide sheets 10 one by one, and the turning gratings 30 and the coupling-out gratings 40 are disposed on the three optical waveguide sheets 10 respectively.

It should be noted that the number of the coupling-in grating 20 and the optical waveguide sheet 10 may be set according to practical situations.

In the embodiment shown in fig. 6, the optical waveguide sheet 10 further includes a functional area grating 60, the functional area grating 60 is disposed between the coupling grating 20 and the turning grating 30, the functional area grating 60 is a one-dimensional grating, and the functional area grating 60 is used for deflecting and transmitting the light coupled into the coupling grating 20 to enter the turning grating 30. The three-color micro-projection machines 50 are respectively arranged in the same side direction and are in one-to-one correspondence with the three in-coupling gratings 20, so that a design scheme that some single-color machines need to be configured by a plurality of micro-projection machines 50 for color output can be compatible, in this embodiment, a small functional area grating 60 is added between the in-coupling gratings 20 and the turning grating 30, the functional area grating 60 is a one-dimensional grating, the grating parameters are that the duty ratio is more than or equal to 30% and less than or equal to 80%, the height is more than or equal to 30nm and less than or equal to 300nm, and the period is in the range of 300nm to 600nm, so that the functional area grating 60 can deflect light entering from the upper and lower in-coupling gratings 20 respectively to the middle to be transmitted to the turning grating 30, and further, the light is better guided to the middle of the eye box for color combination, and the final uniform imaging can be ensured.

Specifically, the one-dimensional grating is one of a blazed grating, an inclined grating, a rectangular grating, a double-ridge grating and a one-dimensional multilayer grating; the two-dimensional grating is one of a square grating, a rectangular grating, a parallelogram grating, a rhombus grating and a two-dimensional multilayer grating.

The blazed grating is a grating having a blazed characteristic, in which the groove surface is not parallel to the normal of the grating, that is, a small included angle exists between the groove surface and the normal of the grating. The sawtooth type grating is an ideal blazed grating, and the cross section of the sawtooth type grating is in a sawtooth structure for diffraction. The tilted grating is a grating in which the plane of the grating and the tangential direction of the grating form a certain inclination angle. The rectangular grating is a grating which diffracts light with a rectangular cross section.

Specifically, the incoupling grating 20 is a one-dimensional grating, and the duty ratio of the incoupling grating 20 is greater than or equal to 30% and less than or equal to 80%; the height of the in-coupling grating 20 is greater than or equal to 50 nanometers and less than or equal to 500 nanometers; when the incoupling grating 20 is a one-dimensional multilayer grating, the number of layers of the one-dimensional multilayer grating is greater than or equal to 1 and less than or equal to 10, the height of each layer is greater than or equal to 50 nanometers and less than 500 nanometers, and the gratings of each layer are one-dimensional and have the same structure; the period of the coupling grating 20 is equal to or greater than 300nm and equal to or less than 600 nm. Thus, the coupling grating 20 can diffract the incident light into different angles and different orders for transmission, and the purpose is to guide the light emitted by the micro-projector 50 into the waveguide with the maximum efficiency, and to adjust specific parameters, thereby finally ensuring that the uniformity of the coupled light intensity meets specific requirements.

Specifically, the inflected grating 30 is a two-dimensional grating, i.e., the two directions have periodic changes, and the duty ratio of the inflected grating 30 is greater than or equal to 30% and less than or equal to 80%; the height of the turning grating 30 is more than or equal to 30 nanometers and less than or equal to 300 nanometers; when the turning grating 30 is a two-dimensional multilayer grating, the number of layers of the two-dimensional multilayer grating is more than or equal to 1 layer and less than or equal to 10 layers, the height of each layer is more than or equal to 30 nanometers and less than or equal to 300 nanometers, and the gratings of each layer are two-dimensional and have the same structure; the period of the turning grating 30 is equal to or greater than 300nm and equal to or less than 600 nm. The arrangement ensures that the turning grating 30 can transmit the light in the optical waveguide sheet 10 in one-dimensional or two-dimensional directions, the purpose is to transmit and amplify the light in a specific direction, and perform pupil expansion transmission on the information of the micro-projector 50, the period of the turning grating 30 is preferably a value obtained by dividing the period of the coupled grating 20 by the root number two, the specific parameters can be adjusted, and finally the adjustment ensures that the uniformity of the coupled light intensity meets the specific requirements.

Specifically, the duty cycle of the coupling-out grating 40 is greater than or equal to 30% and less than or equal to 80%; the height of the coupling-out grating 40 is greater than or equal to 30 nanometers and less than or equal to 300 nanometers; when the coupled-out grating 40 is a one-dimensional multilayer grating, the number of layers of the one-dimensional multilayer grating is greater than or equal to 1 layer and less than or equal to 10 layers, the height of each layer is greater than or equal to 30 nanometers and less than or equal to 300 nanometers, and the gratings of each layer are one-dimensional and have the same structure; the period of the outcoupling grating 40 is 300nm or more and 600nm or less. The arrangement ensures that the coupling-out grating 40 can stably receive the light transmitted by the turning grating 30 and the coupling-in grating 20, and further expands the pupil and couples out the light, so as to uniformly and efficiently couple out the information of the micro-projector 50 to human eyes, the period of the coupling-out grating 40 is preferably consistent with that of the coupling-in grating 20, and specific parameters can be adjusted, and finally the uniformity of the coupled-out light intensity can meet specific requirements.

Specifically, the material of the optical waveguide sheet 10 is glass or optical crystal, the glass is high refractive index glass, the optical crystal is a high refractive index optical crystal, and the refractive index of the optical waveguide sheet 10 is greater than or equal to 1.7 and less than or equal to 2.3. This arrangement is advantageous in ensuring high refractive index characteristics of the optical waveguide sheet 10, which can increase the field angle to realize an optical waveguide sheet 10 with an ultra-large field angle. Of course, different materials can be selected according to actual requirements.

Specifically, the thickness of the optical waveguide sheet 10 is 400 μm or more and 1 mm or less. If the thickness of the optical waveguide sheet 10 is less than 400 μm, the optical waveguide sheet 10 is not easy to manufacture, the processing difficulty of the optical waveguide sheet 10 is increased, and the optical waveguide sheet 10 is easily broken during use, thereby reducing the structural strength of the optical waveguide sheet 10. If the thickness of the optical waveguide sheet 10 is larger than 1 mm, the thickness of the optical waveguide sheet 10 becomes too large, which is disadvantageous for miniaturization of the optical waveguide sheet 10. The thickness of the optical waveguide sheet 10 is limited to a range of 400 μm to 1 mm, thereby ensuring the structural strength of the optical waveguide sheet 10 while ensuring the lightness and thinness of the optical waveguide sheet 10.

It should be noted that the incoupling grating 20, the turning grating 30 and the outcoupling grating 40 are diffraction gratings, so as to ensure the diffraction effect of the incoupling grating 20, the turning grating 30 and the outcoupling grating 40 on light and ensure the uniform transmission of light in the optical waveguide sheet 10. Because of the characteristic of the diffraction grating, make the light intensity of coupling-out can have the inhomogeneity, this inhomogeneity is presented as the inhomogeneity of spatial inhomogeneity and angle, when the inhomogeneity of space leads to human eyes to be in different positions in the eye box, the image brightness observed has difference, the inhomogeneity of angle leads to the light and shade intensity of different field angles to have difference, the optical waveguide system that this application provided can improve the homogeneity of showing, and reduced the size of the optical waveguide piece 10, the cost is reduced, can make the optical waveguide piece 10 more press close to the lens and accord with ergonomic, because the diversity of micro-projector 50, this application has proposed the design scheme that the three-colour micro-projector 50 separates, the compatibility of the combination has been improved.

The near-eye display comprises one or more micro projectors 50 and the optical waveguide system; the micro-projector 50 emits image light to the optical waveguide system, which couples the image light out into the human eye. The optical waveguide system expands the received image light into at least one dimension as the image light propagates within the optical waveguide system. The incoupling grating 20 is designed to couple image light into the optical waveguide sheet 10. Turning grating 30 and outcoupling grating 40 are designed to output the enlarged image light and to be outcoupled to the human eye.

It should be noted that the number of the micro-projectors 50 is set according to the number of the incoupling gratings 20, and the plurality of micro-projectors 50 and the plurality of incoupling gratings 20 are arranged in a one-to-one correspondence.

It should be noted that the micro projector 50 may be a self-luminous active device, such as a micro-OLED or a micro-LED, or a liquid crystal display panel requiring an external light source for illumination, including a transmissive LCD and a reflective LCOS, and a digital micromirror array DMD based on MEMS technology, i.e. a core of DLP and a laser beam scanner LBS, etc. This ensures that the micro-projector 50 can provide monochromatic or color image light source information, the size and shape of the light source needs to match the size and shape of the incoupling grating 20, for example, the micro-projector 50 with a circular incoupling aperture needs to match the circular incoupling grating 20, and different types of micro-projectors 50 are selected to match according to the actual device requirements, so as to optimize the performance of the near-eye display.

It should be noted that the near-eye display may be an AR head-mounted device.

It is to be understood that the above-described embodiments are only a few, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular is intended to include the plural unless the context clearly dictates otherwise, and it should be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of features, steps, operations, devices, components, and/or combinations thereof.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in sequences other than those illustrated or described herein.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.