Diffractive optical waveguide and augmented reality display device
By partitioning the grating structure and phase diffraction elements in the turning area and coupling area of the diffraction light waveguide, the phase difference between different interference light rays is modulated, and the display effect problem caused by equal-path difference light interference in the prior art is solved, and a more efficient display effect is achieved.
Patent Information
- Application Number
- CN202311212086.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-19
- Publication Date
- 2025-03-21
AI Technical Summary
During the expansion of the pupil, existing diffraction light waveguides will produce multiple expansion paths, resulting in constructive interference or destructive interference when light with equal optical paths are coupled out of the human eye, and there will be stripes between light and dark, affecting the display effect.
By partitioning in the turning area and the coupling area, some partitions are provided with grating structures, and some partitions are provided with phase diffraction elements. The phase diffraction element modulates the phase difference between different interference light rays by total internal reflection and phase shift, averaging or eliminating the interference effect.
Without introducing additional optical paths, the phase difference between different interference light rays is modulated to eliminate or average interference effects, significantly improving the display effect of the diffraction light waveguide.
Smart Images
Figure CN119667842A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of optical technology, and in particular to a diffraction optical waveguide and an augmented reality display device. Background Art
[0002] Augmented reality is a technology that integrates the real world and virtual information. The augmented reality display system usually includes a micro projector and an optical display screen. The micro projector provides virtual display content for the augmented reality display system and projects it into the human eye through the optical display screen. The optical display screen is usually a transparent optical component, so that users can also see the real world through the optical display screen.
[0003] Diffraction waveguide is a way to realize optical display screen. Grating structure is usually used to expand the exit pupil. There will be multiple expansion paths when realizing the exit pupil expansion, which will then generate a large number of light rays with equal optical path differences transmitted in the same direction. These light rays will produce constructive interference or destructive interference when coupled out to the human eye, resulting in light and dark stripes in the display image, which greatly affects the display effect. Summary of the invention
[0004] The embodiments of the present application provide a diffractive optical waveguide and an augmented reality display device, which can improve or even eliminate undesirable interference effects, thereby enhancing the display effect of the diffractive optical waveguide.
[0005] A diffraction light waveguide comprises a waveguide substrate, an incoupling region, a turning region and an outcoupling region, wherein the incoupling region is used to couple image light, wherein:
[0006] The turning area includes a plurality of turning partitions, wherein the turning partitions include a turning partition with a grating structure and a turning partition with a phase diffraction element, wherein the turning partition with the grating structure is used to expand and propagate image light, and the turning partition with the phase diffraction element is used to totally reflect and propagate the image light and change the phase of the image light; and / or,
[0007] The outcoupling area includes a plurality of outcoupling partitions, and the outcoupling partitions include an outcoupling partition with a grating structure and an outcoupling partition with a phase diffraction element. The outcoupling partition with the grating structure is used to expand and couple out image light, and the outcoupling partition with the phase diffraction element is used to totally reflect and propagate the image light and change the phase of the image light.
[0008] In practice, the grating direction and the grating period of the grating structure in each turning partition provided with the grating structure are consistent, the grating direction and the grating period of the grating structure in each out-coupling partition provided with the grating structure are consistent, and the parameters of the phase diffraction element in each turning partition provided with the phase diffraction element and the out-coupling partition are randomly set.
[0009] A diffraction optical waveguide comprises a waveguide substrate, an incoupling region and an outcoupling region, wherein the incoupling region is used to couple in image light; the outcoupling region comprises a plurality of outcoupling partitions, wherein the outcoupling partitions comprise an outcoupling partition with a grating structure and an outcoupling partition with a phase diffraction element, wherein the outcoupling partition with the grating structure is used to expand and couple out the image light, and the outcoupling partition with the phase diffraction element is used to propagate the image light by total reflection and change the phase of the image light.
[0010] In practice, the parameters of the phase diffraction elements in each of the turning subareas and the outcoupling subareas provided with the phase diffraction elements are randomly set.
[0011] In practice, the phase diffraction element includes a composite structure of at least two periodic units along the same periodic direction.
[0012] Practically, the period of the periodic unit is 100nm-200nm.
[0013] In practice, the turning area and / or the outcoupling area are regularly partitioned or randomly partitioned, the contour lines of the turning partitions include straight lines and / or curves, and the contour lines of the outcoupling partitions include straight lines and / or curves.
[0014] Implementably, the turning partition has a size smaller than the entrance pupil size in at least one direction parallel to the waveguide substrate surface, and / or the outcoupling partition has a size smaller than the entrance pupil size in at least one direction parallel to the waveguide substrate surface.
[0015] Practically, the number of turning partitions provided with phase diffraction elements gradually decreases in a direction away from the coupling-in region, and / or the number of outcoupling partitions provided with phase diffraction elements gradually decreases in a direction away from the coupling-in region.
[0016] An augmented reality display device, comprising: a projection optical machine and a diffraction optical waveguide as described in any one of the above items.
[0017] The diffraction optical waveguide provided in the present application divides the turning area and / or the out-coupling area into partitions based on the existing architecture. A grating structure is arranged in one of the partitions to ensure the original functions of the turning area and / or the out-coupling area, and a phase diffraction element is arranged in another partition. When the image light is incident on these partitions provided with the phase diffraction elements, total internal reflection and phase shift occur without diffraction, thereby modulating the phase difference between different interference light rays without introducing an additional optical path. When the phase difference changes, the interference effect between different light rays is averaged or even eliminated, thereby improving the display effect of the diffraction optical waveguide.
[0018] The augmented reality display device provided in the present application includes the aforementioned diffractive optical waveguide, and thus has the advantages of the aforementioned diffractive optical waveguide. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0020] Figure 1 A schematic diagram of a diffractive optical waveguide provided by the prior art;
[0021] Figure 2 A schematic diagram of a diffractive optical waveguide provided in one embodiment of the present application;
[0022] Figure 3 A schematic diagram of a diffractive optical waveguide provided for another embodiment of the present application;
[0023] Figure 4 A schematic diagram of a diffractive optical waveguide provided for another embodiment of the present application;
[0024] Figure 5 A schematic diagram of a diffractive optical waveguide provided for another embodiment of the present application;
[0025] Figure 6 A schematic diagram of a phase diffraction element provided in one embodiment of the present application;
[0026] Figure ID:
[0027] 110, 210, 410: waveguide substrate;
[0028] 120, 220, 420: coupling area;
[0029] 130, 230: turning point area;
[0030] 230A, 230B: turning zone;
[0031] 140, 240, 430: outcoupling area;
[0032] 240A, 240B, 430A, 430B: decoupled partitions. DETAILED DESCRIPTION
[0033] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.
[0034] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.
[0035] A diffraction optical waveguide provided by the prior art, referring to Figure 1 , including a waveguide substrate 110, a coupling-in region 120, a turning region 130 and a coupling-out region 140. The image light emitted by the optical machine is diffracted by the coupling-in grating in the coupling-in region 120 and then transmitted in the direction of the coupling-out region 130 by total reflection. Each time the image light is incident on the coupling-in region 130, it will be diffracted by the turning grating in the turning region 130. A portion of the image light continues to be transmitted in the original direction, and a portion of the image light is deflected and transmitted in the direction of the coupling-out region 140. Finally, the image light is diffracted and coupled out by the coupling-out grating in the coupling-out region 140 and is incident on the human eye. Since the diffraction effect of the turning grating on the image light has not only the 1st order diffraction, but also the -1st order diffraction, the image grating that is deflected and transmitted in the direction of the coupling-out region 140 will be partially deflected back again and transmitted along the extension direction of the turning region. Figure 1After the image light 111 is diffracted by the first order of the turning grating, it is split into a light 112 that is transmitted in the direction of 140. When 112 is totally internally reflected in 130 for the next time, it is again diffracted by the first order of the turning grating to split into a light 114 that is transmitted in the direction of 130. When 114 is totally internally reflected in 130 for the next time, it is again diffracted by the first order of the turning grating to split into a light 121 that is transmitted in the direction of 140. By analogy, each time the image light is totally internally reflected in 130, it will split into a light that is transmitted in the direction of 130 or 140, thereby generating a large number of light rays with equal optical path differences that are transmitted in the direction of 140. These light rays will generate constructive interference or destructive interference when coupled out to the human eye, resulting in the appearance of light and dark stripes in the display image, which greatly affects the display effect.
[0036] According to one aspect of the present application, referring to Figure 2 and 3 The embodiment of the present application provides a diffraction optical waveguide, including a waveguide substrate 210, a coupling-in region 220, a turning region 230 and a coupling-out region 240, wherein the coupling-in region 220 is used to couple in image light, wherein the turning region 230 includes a plurality of coupling-out regions, wherein the coupling-out regions include a coupling-out region 230A provided with a grating structure and a coupling-out region 230B provided with a phase diffraction element, wherein the coupling-out region 240 includes a plurality of coupling-out regions, wherein the coupling-out region includes a coupling-out region 240A provided with a grating structure and a coupling-out region 240B provided with a phase diffraction element, wherein the coupling-out region 240 includes a plurality of coupling-out regions, wherein the coupling-out region includes a coupling-out region 240A provided with a grating structure and a coupling-out region 240B provided with a phase diffraction element, wherein the coupling-out region 240A provided with a grating structure is used to expand and couple out image light, and the coupling-out region 240B provided with a phase diffraction element is used to totally reflect and propagate image light and change the phase of image light.
[0037] According to one aspect of the present application, referring to Figure 4 and 5 The embodiment of the present application provides a diffraction optical waveguide, including a waveguide substrate 410, a coupling-in region 420 and a coupling-out region 430, wherein the coupling-in region 410 is used to couple-in image light; the coupling-out region 430 includes a plurality of coupling-out partitions, wherein the coupling-out partitions include a coupling-out partition 430A provided with a grating structure and a coupling-out partition 430B provided with a phase diffraction element, wherein the coupling-out partition 430A provided with a grating structure is used to expand and couple-out image light, and the coupling-out partition 430B provided with a phase diffraction element is used to totally reflect and propagate image light and change the phase of the image light.
[0038] The diffraction optical waveguide provided in the present application divides the turning area and / or the out-coupling area into partitions based on the existing architecture. A grating structure is arranged in one of the partitions to ensure the original functions of the turning area and / or the out-coupling area, and a phase diffraction element is arranged in another partition. When the image light is incident on these partitions provided with the phase diffraction elements, total internal reflection and phase shift occur without diffraction, thereby modulating the phase difference between different interference light rays without introducing an additional optical path. When the phase difference changes, the interference effect between different light rays is averaged or even eliminated, thereby improving the display effect of the diffraction optical waveguide.
[0039] Specifically, refer to Figure 2 , the image light emitted by the optical machine is diffracted by the coupling grating in the coupling region 220, and then transmitted by total reflection in the direction of the turning region 230, and transmitted to the turning region 230 including the turning partition 230A and the turning partition 230B. The turning partition 230A is provided with a grating structure, and the image light undergoes conventional diffraction when incident on the turning partition 230A, which expands and propagates the image light and realizes the original function of the turning region; the turning partition 230B is provided with a phase diffraction element, and the image light undergoes total internal reflection and no longer undergoes diffraction when incident on the turning partition 230B, thereby avoiding the introduction of an additional optical path to generate interference, and the image light undergoes phase shift under the action of the phase diffraction element, and at this time, when multiple light rays interfere, the originally fixed optical path difference is disrupted, and the interference effect between different light rays is averaged or even eliminated.
[0040] In some embodiments, reference Figure 3 , the out-coupling area 240 can also be divided into zones, and the image light is transmitted to the out-coupling area 240 including the out-coupling zone 240A and the out-coupling zone 240B. A grating structure is arranged in the out-coupling zone 240A, and conventional diffraction occurs when the image light is incident on the out-coupling zone 240A, and the propagation is extended and the image grating is coupled out, thereby realizing the original function of the out-coupling zone; a phase diffraction element is arranged in the out-coupling zone 240B, and total internal reflection no longer diffracts when the image light is incident on the out-coupling zone 240B. Similarly, the out-coupling grating partitions are arranged with grating structures and phase diffraction elements to avoid introducing additional light paths to generate interference, and the image light is phase-shifted under the action of the phase diffraction element. At this time, when multiple light rays interfere, the originally fixed optical path difference is disrupted, and the interference effect between different light rays is averaged or even eliminated.
[0041] Practically, for Figure 2 and 3The diffraction waveguide structure shown includes a coupling-in region, a turning region, and a coupling-out region. The grating structure in the turning region 230A is usually a one-dimensional grating. The grating period and grating direction of the grating structure in each turning region 230A are the same, while other grating parameters such as duty cycle, depth, or tooth shape can be the same or different. The grating structure in the coupling-out region 240A is usually also a one-dimensional grating. The grating period and grating direction of the grating structure in each coupling-out region 240A are the same, while other grating parameters such as duty cycle, depth, or tooth shape can be the same or different. Figure 4 and 5 The diffraction waveguide structure including the coupling-in region and the coupling-out region shown in the figure, the grating structure in the coupling-out region 430A can generally be a one-dimensional grating and / or a two-dimensional grating. When the coupling-out region 230A is a two-dimensional grating, the grating period and grating direction of the grating structure are the same, while other grating parameters such as duty cycle, depth or tooth shape can be the same or different. When the coupling-out region 230A is a one-dimensional grating, at least two one-dimensional gratings with different grating directions are included. Figure 4 Each out-coupling partition 430A can be set as a one-dimensional grating, and the one-dimensional gratings with two different grating directions are randomly filled, and the grating directions of the one-dimensional gratings in two adjacent out-coupling partitions 430A are different. Figure 5 A two-dimensional grating is set in the out-coupling partition 430A in the middle part of the out-coupling region 430, a one-dimensional grating in one grating direction is set in the out-coupling partition 430A in the upper part of the out-coupling region 430, and a one-dimensional grating in another grating direction is set in the out-coupling partition 430A in the lower part of the out-coupling region 430.
[0042] In practice, the partitions of the turning area and / or the out-coupling area may be regular partitions, or the partitions of the turning area and / or the out-coupling area may be irregular partitions, i.e., random partitions. Specifically, regular partitions are partitions that divide the turning area and / or the out-coupling area into multiple partitions of the same shape (except for the partitions at the boundaries) along at least one direction, for example Figure 3 The turning area is divided into multiple partitions along one direction. Figure 2 The middle turning area is divided into a plurality of partitions along two different directions. Of course, in other embodiments, the partitions may also be divided along more directions (such as three directions, four directions, etc.).
[0043] It is feasible that the contour lines of the turning partition and the coupling-out partition include straight lines and / or curves. The shapes of the turning partition and the coupling-out partition may be circular, elliptical, polygonal, or a shape composed of straight lines and curves. The size of the turning partition and the coupling-out partition in at least one direction is the same as or smaller than the entrance pupil size, so as to avoid the problem of missing pupil in the eyebox within the eye movement range and not affect the human eye viewing the image within the eye movement range. Usually, the entrance pupil size is 2mm-4mm, and the maximum size of the turning partition and the coupling-out partition in at least one direction should be smaller than this size. Furthermore, in order to better avoid the problem of missing pupil in the eyebox, the maximum size of the turning partition and the coupling-out partition may be less than 1mm.
[0044] Among them, the turning partition and the coupling-out partition are independent of each other, and the shapes and sizes of the partitions do not affect each other.
[0045] Furthermore, in one embodiment of the present application, a phase diffraction element is provided, comprising a composite structure of at least two periodic units along the same periodic direction, wherein the period of each periodic unit may be the same or different, and the structure of each periodic unit may be the same or different.
[0046] It should be noted that, in order to disrupt the originally fixed optical path difference between the light rays by changing the phase of the light rays when multiple light rays interfere, and average or even eliminate the interference effect between different light rays, it is feasible to randomly set the parameters of the phase diffraction elements in each turning partition and out-coupling partition provided with the phase diffraction element, so that the phase diffraction elements in different turning partitions or out-coupling partitions produce random phase shifts on the image light rays, and the random phase shift of the interference light rays is more helpful in eliminating the interference effect. Moreover, when the phase diffraction element is implemented as a composite structure including at least two periodic units, the random change of the phase of the image light rays has a higher degree of freedom; combined with the control of the period size of each periodic unit, it can simultaneously avoid the diffraction of the image light rays when they are incident on the phase diffraction element and introduce new interference.
[0047] The period of the periodic unit should be such that no diffraction occurs when the image light enters the phase diffraction element. In practice, the period of the periodic unit is 100nm-200nm.
[0048] For example, reference Figure 6 The phase diffraction element includes three periodic units along the same periodic direction, the period of the first periodic unit is P1, the period of the second periodic unit is P2, and the period of the third periodic unit is P3, and P1, P2 and P3 are different. It should be noted that Figure 6The structure shown is merely an example of a specific implementation of a phase diffraction element. Phase diffraction elements of the illustrated structure are provided in some turning partitions and / or out-coupling partitions, and other turning partitions and / or out-coupling partitions may also be provided with phase diffraction elements of other structural implementations. The phase diffraction elements in different turning partitions and / or out-coupling partitions may be different to achieve random phase shift of the light phase.
[0049] In addition, in the embodiments provided in the present application, the pupil expansion efficiency and the outcoupling efficiency can be modulated by adjusting the position and number of the turning partition including the grating structure and the outcoupling partition including the grating structure, thereby improving the uniformity of the diffraction optical waveguide.
[0050] In practice, the number of turning subareas provided with phase diffraction elements gradually decreases in the direction away from the coupling-in area, and / or the number of out-coupling subareas provided with phase diffraction elements gradually decreases in the direction away from the coupling-in area. It can be understood that the energy of the image light is continuously attenuated with expansion and out-coupling. In order to adjust the uniformity of the light output, the number of subareas provided with grating structures in the turning area and out-coupling area near the front of the expansion direction is smaller than that in the rear of the expansion direction, and the number of subareas provided with phase diffraction elements in the turning area and out-coupling area near the front of the expansion direction is greater than that in the rear of the expansion direction.
[0051] It should be noted that Figure 2-5 The partitioning method of the turning area and the partitioning method of the out-coupling area shown in the figure, including the position, number, size and shape of the turning partition of the grating structure, the position, number, size and shape of the out-coupling partition of the grating structure, the position, number, size and shape of the turning partition of the phase diffraction element, and the position, number, size and shape of the out-coupling partition of the phase diffraction element, are all for illustration and do not limit the scope of protection claimed in this application.
[0052] According to one aspect of the present application, an augmented reality display device is also provided, comprising: a projection optical machine and a diffraction optical waveguide as described above. The projection optical machine is used to emit image light. The augmented reality display device can be specifically implemented as augmented reality glasses or augmented reality helmets. The augmented reality display device provided by the present application includes the aforementioned diffraction optical waveguide, and thus has the advantages of the aforementioned diffraction optical waveguide.
[0053] The above specific implementations do not constitute a limitation on the protection scope of this application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of this application should be included in the protection scope of this application.
Claims
1. A diffractive optical waveguide, characterized in that: It includes a waveguide substrate, a coupling-in region, a turning region and a coupling-out region, wherein the coupling-in region is used to couple image light, wherein: The turning area includes a plurality of turning partitions, wherein the turning partitions include a turning partition with a grating structure and a turning partition with a phase diffraction element, wherein the turning partition with the grating structure is used to expand and propagate image light, and the turning partition with the phase diffraction element is used to totally reflect and propagate the image light and change the phase of the image light; and / or, The outcoupling area includes a plurality of outcoupling partitions, and the outcoupling partitions include an outcoupling partition with a grating structure and an outcoupling partition with a phase diffraction element. The outcoupling partition with the grating structure is used to expand and couple out image light, and the outcoupling partition with the phase diffraction element is used to totally reflect and propagate the image light and change the phase of the image light.
2. The diffractive optical waveguide according to claim 1, characterized in that: The grating direction and the grating period of the grating structure in each turning partition provided with the grating structure are consistent, the grating direction and the grating period of the grating structure in each out-coupling partition provided with the grating structure are consistent, and the parameters of the phase diffraction element in each turning partition provided with the phase diffraction element and the out-coupling partition are randomly set.
3. A diffractive optical waveguide, characterized in that: It includes a waveguide substrate, a coupling-in region and a coupling-out region, wherein the coupling-in region is used to couple in image light; the coupling-out region includes a plurality of coupling-out partitions, wherein the coupling-out partitions include a coupling-out partition with a grating structure and a coupling-out partition with a phase diffraction element, wherein the coupling-out partition with the grating structure is used to expand and couple out the image light, and the coupling-out partition with the phase diffraction element is used to propagate the image light by total reflection and change the phase of the image light.
4. The diffractive optical waveguide according to claim 3, characterized in that: The parameters of the phase diffraction elements in each of the turning partitions and the outcoupling partitions provided with the phase diffraction elements are randomly set.
5. The diffractive optical waveguide according to claim 1 or 3, characterized in that: The phase diffraction element includes a composite structure of at least two periodic units along the same periodic direction.
6. The diffractive optical waveguide according to claim 5, characterized in that: The period of the periodic unit is 100nm-200nm.
7. The diffractive optical waveguide according to claim 1 or 3, characterized in that: The turning area and / or the coupling-out area are regularly partitioned or randomly partitioned, the contour lines of the turning partitions include straight lines and / or curves, and the contour lines of the coupling-out partitions include straight lines and / or curves.
8. The diffractive optical waveguide according to any one of claims 5 to 7, characterized in that: The turning partition has a size smaller than the entrance pupil size at least in one direction parallel to the waveguide substrate surface, and / or the outcoupling partition has a size smaller than the entrance pupil size at least in one direction parallel to the waveguide substrate surface.
9. The diffractive optical waveguide according to claim 1 or 3, characterized in that: The number of the turning subregions provided with phase diffraction elements gradually decreases in a direction away from the coupling-in region, and / or the number of the outcoupling subregions provided with phase diffraction elements gradually decreases in a direction away from the coupling-in region.
10. An augmented reality display device, characterized in that: The augmented reality display device comprises: a projection optical machine and a diffraction optical waveguide as described in any one of claims 1-9.