CN216248597U

CN216248597U - Diffraction grating waveguide element

Info

Publication number: CN216248597U
Application number: CN202122892990.2U
Authority: CN
Inventors: 王丙杰; 史晓刚; 张威; 张洪
Original assignee: Beijing Xloong Technology Co ltd
Current assignee: Beijing Xloong Technology Co ltd
Priority date: 2021-11-19
Filing date: 2021-11-19
Publication date: 2022-04-08
Anticipated expiration: 2031-11-19

Abstract

The utility model discloses a diffraction grating waveguide element, comprising: the grating array comprises an optical substrate, an incident grating, an orthogonal grating array, a turning grating and an emergent grating; the incident grating, the turning grating, the orthogonal grating array and the emergent grating are distributed on the surface of the optical substrate at intervals; the turning grating is positioned on one side of the incident grating, and the orthogonal grating array is positioned on the other side of the incident grating and is positioned on the opposite side of the turning grating; the emergent grating is arranged on the side surface of the turning grating. By arranging the orthogonal grating array on the other side of the incident grating, the-1 st-order diffraction light which is originally generated by the incident grating and becomes stray light is reflected back to the turning grating for utilization, so that the light efficiency of the grating waveguide element is improved, and stray light is reduced.

Description

Diffraction grating waveguide element

Technical Field

The utility model relates to the field of near-to-eye display devices, in particular to a diffraction grating waveguide element.

Background

Near-eye display devices have evolved rapidly as virtual reality and augmented reality technologies have become recognized and accepted. In the near-eye display device, the grating waveguide display technology is to realize the incidence, turning and emission of light by using a diffraction grating, realize light transmission by using the total reflection principle, transmit an image of a micro display to human eyes and further see a virtual image. The grating waveguide technology has many advantages of good perspective effect, light weight, low mass production cost and the like, and is considered as a development direction of the AR near-eye display technology, but the existing grating waveguide still has the problem that the optical energy utilization efficiency needs to be improved.

The structure of the existing grating waveguide device is shown in fig. 1, and the whole device is composed of an optical substrate and a grating positioned on the surface of the optical substrate. The optical substrate is generally a planar structure, and the material thereof may be optical material such as optical glass, optical plastic, etc. The main optical surfaces of the optical substrate are two surfaces parallel to each other, and the grating is located on one surface of the optical substrate, and there are usually three grating regions: an entrance grating 110, a turning grating 120 and an exit grating 130. The grating waveguide works on the principle that as shown in fig. 2, light 214 with image information from the projection system 210 is projected onto the incident grating 110, and the incident grating 110 will diffract to generate two diffracted lights, namely +1 st-order diffracted light 216 and-1 st-order diffracted light 218. When the diffracted light satisfies the total reflection condition of the optical substrate, i.e., the incident angle to the optical surface is larger than the critical angle of total reflection of the optical substrate, the light beam is totally reflected and nearly transmitted without loss in the optical substrate. The +1 st order diffraction light 216 generated by the incident grating 110 is transmitted toward the + y direction (i.e., the y-axis is positive) and toward the turning grating 120, when entering the area of the turning grating 120, due to the diffraction effect of the turning grating 120, a series of diffraction light transmitted toward the exit grating 130 is generated while continuing to be transmitted along the + y direction, and the part of diffraction light is transmitted to the exit grating 130, and after being diffracted by the exit grating 130, the emitted diffraction light 222 enters the human eye 212 to be perceived. The-1 st order diffracted light 218 generated by the incident grating 110 is transmitted toward the-y direction (i.e., the y-axis direction is negative) and cannot be transmitted to the turning grating 120 and the exit grating 130, so that it cannot be effectively utilized, and a part of the diffracted light may also become stray light of the system, which affects the performance of the diffraction waveguide device.

In view of the above, the present invention is particularly proposed.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a diffraction grating waveguide element, which can effectively utilize-1 st-order diffraction light generated by an incident grating and solve the problem of low energy utilization rate of the existing grating waveguide device.

The purpose of the utility model is realized by the following technical scheme:

an embodiment of the present invention provides a diffraction grating waveguide element including:

the grating array comprises an optical substrate, an incident grating, an orthogonal grating array, a turning grating and an emergent grating; wherein,

the incident grating, the turning grating, the orthogonal grating array and the emergent grating are distributed on the surface of the optical substrate at intervals;

the turning grating is positioned on one side of the incident grating, and the orthogonal grating array is positioned on the other side of the incident grating and is positioned on the opposite side of the turning grating;

the emergent grating is arranged on the side surface of the turning grating.

Compared with the prior art, the diffraction grating waveguide element provided by the utility model has the beneficial effects that:

the orthogonal grating array is arranged on the other side of the incident grating opposite to the turning grating, and the-1 st-order diffraction light generated by the incident grating is reflected by the orthogonal grating array to enter the turning grating for utilization, so that the-1 st-order diffraction light generated by the incident grating is fully utilized, the light effect of the grating waveguide is improved, the generation of stray light is avoided, and the display effect is further improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

FIG. 1 is a schematic diagram of a prior art diffractive waveguide device;

FIG. 2 is a schematic illustration of light conduction of a prior art diffractive waveguide device;

FIG. 3 is a schematic structural diagram of a diffractive waveguide element according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a diffractive waveguide element according to an embodiment of the present invention, in which (a) is a schematic diagram of a first and a second orthogonal sub-gratings of an orthogonal grating array incident to light of one angle, (b) is a schematic diagram of a first and a second orthogonal sub-gratings of an orthogonal grating array incident to light of another angle, and (c) is a schematic diagram of a first and a second orthogonal sub-gratings of an orthogonal grating array incident to light of yet another angle;

fig. 5 is a schematic structural diagram of a diffractive waveguide element according to an embodiment of the present invention.

Detailed Description

The technical scheme in the embodiment of the utility model is clearly and completely described below by combining the attached drawings in the embodiment of the utility model; it is to be understood that the described embodiments are merely exemplary of the utility model, and are not intended to limit the utility model to the particular forms disclosed. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

The terms that may be used herein are first described as follows:

the term "and/or" means that either or both can be achieved, for example, X and/or Y means that both cases include "X" or "Y" as well as three cases including "X and Y".

The terms "comprising," "including," "containing," "having," or other similar terms of meaning should be construed as non-exclusive inclusions. For example: including a feature (e.g., material, component, ingredient, carrier, formulation, material, dimension, part, component, mechanism, device, process, procedure, method, reaction condition, processing condition, parameter, algorithm, signal, data, product, or article of manufacture), is to be construed as including not only the particular feature explicitly listed but also other features not explicitly listed as such which are known in the art.

The term "consisting of … …" is meant to exclude any technical feature elements not explicitly listed. If used in a claim, the term shall render the claim closed except for the inclusion of the technical features that are expressly listed except for the conventional impurities associated therewith. If the term occurs in only one clause of the claims, it is defined only to the elements explicitly recited in that clause, and elements recited in other clauses are not excluded from the overall claims.

Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "secured," etc., are to be construed broadly, as for example: can be fixedly connected, can also be detachably connected or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms herein can be understood by those of ordinary skill in the art as appropriate.

When concentrations, temperatures, pressures, dimensions, or other parameters are expressed as ranges of values, the ranges are to be understood as specifically disclosing all ranges formed from any pair of upper, lower, and preferred values within the range, regardless of whether ranges are explicitly recited; for example, if a numerical range of "2 ~ 8" is recited, then the numerical range should be interpreted to include ranges of "2 ~ 7", "2 ~ 6", "5 ~ 7", "3 ~ 4 and 6 ~ 7", "3 ~ 5 and 7", "2 and 5 ~ 7", and the like. Unless otherwise indicated, the numerical ranges recited herein include both the endpoints thereof and all integers and fractions within the numerical range.

The terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," and the like are used in an orientation or positional relationship that is indicated based on the orientation or positional relationship shown in the drawings for ease of description and simplicity of description only, and are not intended to imply or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting herein.

The diffraction grating waveguide element provided by the present invention is described in detail below. Details which are not described in detail in the embodiments of the utility model belong to the prior art which is known to the person skilled in the art. Those not specifically mentioned in the examples of the present invention were carried out according to the conventional conditions in the art or conditions suggested by the manufacturer. The reagents or instruments used in the examples of the present invention are not specified by manufacturers, and are all conventional products available by commercial purchase.

As shown in fig. 3, a diffraction grating waveguide device according to the present invention is a grating waveguide device with a novel structure, and includes:

an optical substrate 350, an incident grating 310, an orthogonal grating array 340, a turning grating 320 and an exit grating 330; wherein,

the incident grating 310, the turning grating 320, the orthogonal grating array 340 and the emergent grating 330 are arranged on the surface of the optical substrate 350 at intervals;

the turning grating 320 is located on one side of the incident grating 310, and the orthogonal grating array 340 is located on the other side of the incident grating 310, on the opposite side of the turning grating 320;

the exit grating 330 is located at the side of the turning grating 320.

Referring to fig. 3, 4(a), 4(b) and 4(c), in the above-mentioned grating waveguide component, the orthogonal grating array 340 is composed of a plurality of sub-gratings which are arranged, and the plurality of sub-gratings includes two types of sub-gratings, namely a first orthogonal sub-grating and a second orthogonal sub-grating, and the two types of sub-gratings are arranged alternately.

In the grating waveguide element, a relationship between the period Λ 1 of the first orthogonal sub-grating, the period Λ 2 of the second orthogonal sub-grating, and the period Λ 0 of the incident grating 310 is:

in the grating waveguide element, the grating groove direction of the first orthogonal sub-grating is perpendicular to the grating groove direction of the second orthogonal sub-grating;

the included angle between the grating groove direction of the first and second orthogonal sub-gratings and the grating groove direction of the incident grating 310 is 45 degrees.

The condition is met, the light reflected by the orthogonal grating array can be better ensured to be incident on the incident grating 310 and finally transmitted to human eyes after being emergent through the turning grating 320 and the emergent grating 330, and the utilization rate of stray light is improved.

In summary, in the diffraction grating waveguide element according to the embodiment of the utility model, the orthogonal grating array formed by the first and second orthogonal sub-gratings which are alternately arranged is arranged at one end of the incident grating for generating the-1 st-order diffracted light, so that the-1 st-order diffracted light can be reflected into the turning grating for utilization, and not only is the-1 st-order diffracted light generated by the incident grating fully utilized, but also the light efficiency of the grating waveguide is improved, the generation of stray light is avoided, and the display effect is further improved.

In order to more clearly show the technical solutions and the technical effects provided by the present invention, the diffraction grating waveguide element provided by the embodiments of the present invention is described in detail with specific embodiments below.

Examples

As shown in fig. 3, an embodiment of the present invention provides a diffraction grating waveguide element, which is composed of an optical substrate 350 and gratings located on portions of the surface of the optical substrate 350, and specifically includes: an incident grating 310, an orthogonal grating array 340, a turning grating 320 and an exit grating 330; the side surface of the turning grating 320 is provided with an emergent grating 330, the turning grating 320 is positioned on one side of the incident grating 310, and the orthogonal grating array 340 is positioned on the other side of the incident grating 310 and is positioned on the opposite side of the turning grating 320; as shown in fig. 4(a), 4(b) and 4(c), the orthogonal grating array 340 is formed by arranging a plurality of sub-gratings, specifically, a plurality of sub-gratings are arranged in rows, the plurality of sub-gratings include two types of sub-gratings, namely, a first orthogonal sub-grating 341 and a second orthogonal sub-grating 342, and the plurality of sub-gratings are alternately arranged according to the first orthogonal sub-grating and the second orthogonal sub-grating to form the orthogonal grating array 340; specifically, the first orthogonal sub-grating 341 and the second orthogonal sub-grating 342 are perpendicular to each other, light is reflected by the first orthogonal sub-grating 341 and the second orthogonal sub-grating 342, and both the first orthogonal sub-grating 341 and the second orthogonal sub-grating 342 play a role in reflecting light, as shown in fig. 4(a), 4(b), and 4 (c); after the light is incident from different angles, the light is reflected by the first orthogonal sub-grating 341 and the second orthogonal sub-grating 342 in sequence, and the light is reflected back to the light incident side of the orthogonal grating array 340.

Fig. 5 illustrates the operation principle of the diffraction grating waveguide component of the present embodiment, in which the incident grating 310 is used to guide the virtual image beam emitted from the projection system into the diffraction grating waveguide component, the incident grating 310 diffracts the incident light in two approximately opposite directions, and a part of the incident light is transmitted toward the region of the turning grating 316 (i.e., +1 st-order diffracted light 216), and is diffracted by the turning grating 320 to generate a diffracted light beam transmitted toward the exit grating 330; the part of diffracted light beams are transmitted to the emergent grating 330, and enter human eyes to be perceived after being diffracted by the emergent grating 330; the incident grating 310 transmits another part of diffracted light (i.e., -1 st-order diffracted light 218) to the orthogonal grating array 340 area, and after being reflected by each of the first orthogonal sub-grating 341 and the second orthogonal sub-grating 342 which are perpendicular to each other in the orthogonal grating array 340 in sequence, the reflected light enters the turning grating 320 in the + y direction, and then is diffracted by the turning grating 320 to generate a diffracted light beam transmitted to the exit grating 330, and the part of diffracted light is transmitted to the exit grating 330, and enters human eyes to be perceived after being diffracted by the exit grating 330, so that the utilization of the-1 st-order diffracted light 218 which is originally stray light is realized, the light efficiency is improved, and the display effect is also improved.

In the present embodiment, the relationship between the period Λ 1 of the first orthogonal sub-grating 341, the period Λ 2 of the second orthogonal sub-grating 342, and the period Λ 0 of the incident grating 310 in the orthogonal grating array 340 is:

through detection, when the period Λ 1 of the first orthogonal sub-grating 341, the period Λ 2 of the second orthogonal sub-grating 342, and the period Λ 0 of the incident grating 310 satisfy the above formula (1), the light reflected back by the orthogonal grating array 340 can be better ensured to be transmitted to human eyes after being incident on the incident grating 310 and finally being emitted through the turning grating 320 and the exit grating 330.

In summary, in the diffraction grating waveguide element according to the embodiment of the utility model, the orthogonal grating array 340 is disposed on the other side of the incident grating 320, so that-1 st-order diffracted light 218, which is originally stray light generated by the incident grating 310, is reflected back to the turning grating 320 to be utilized, thereby improving the light efficiency of the grating waveguide element and reducing stray light.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims. The information disclosed in this background section is only for enhancement of understanding of the general background of the utility model and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Claims

1. A diffraction grating waveguide element, comprising:

an optical substrate (350), an incident grating (310), an orthogonal grating array (340), a turning grating (320), and an exit grating (330); wherein,

the incident grating (310), the turning grating (320), the orthogonal grating array (340) and the emergent grating (330) are distributed on the surface of the optical substrate (350) at intervals;

the turning grating (320) is positioned on one side of the incident grating (310), and the orthogonal grating array (340) is positioned on the other side of the incident grating (310) and is positioned on the opposite side of the turning grating (320);

the exit grating (330) is located at a side of the turning grating (320).

2. The diffraction grating waveguide element according to claim 1, wherein the orthogonal grating array (340) is comprised of an arrangement of a plurality of sub-gratings, including two types of sub-gratings, a first orthogonal sub-grating and a second orthogonal sub-grating, the two types of sub-gratings being arranged alternately.

3. The diffraction grating waveguide element according to claim 2, wherein the relationship between the period Λ 1 of the first orthogonal sub-grating, the period Λ 2 of the second orthogonal sub-grating and the period Λ 0 of the incident grating (310) is:

4. the diffraction grating waveguide element of claim 2, wherein the grating groove direction of the first orthogonal sub-grating is perpendicular to the grating groove direction of the second orthogonal sub-grating;

and the included angle between the grating groove direction of the first and second orthogonal sub-gratings and the grating groove direction of the incident grating (310) is 45 degrees.