A symmetrical pupil dilator and near-eye display device

Abstract

This invention relates to a symmetrical pupil-expanding device and a near-eye display device, comprising: a first waveguide sheet and a second waveguide sheet arranged parallel to each other and stacked, and a first steering mirror and a second steering mirror arranged correspondingly; a first waveguide structure and a second waveguide structure mirror-symmetrical, the steering reflection slope of the first steering mirror being parallel to the first beam splitter; the steering reflection slope of the second steering mirror being parallel to the second beam splitter; an adhesive layer disposed between the first waveguide sheet and the second waveguide sheet; and a geometric coupling prism disposed in the middle region between the transition structures, the projection surface of which facing the second direction is quadrilateral, including opposing light-incident edges and light-outcident edges, as well as opposing first side edges and second side edges, the light-incident edge and the first side edge forming an acute angle θ = 60°-80°, and the first side edge being perpendicular to the light-outcident edge. Compared with traditional solutions, the height of the transition structure in this solution only needs to meet the transmission of half of the field of view to achieve full-field display, exhibiting strong symmetry, high light energy utilization, and small size.

Description

Technical Field

[0001] This invention relates to the field of augmented reality technology, and in particular to a symmetrical pupil expansion device and a near-eye display device. Background Technology

[0002] Augmented Reality (AR) technology is a technique that cleverly integrates virtual information with the real world. It simulates computer-generated text, images, 3D models, music, and videos, applying them to the real world to supplement its real-world information and thus "enhance" it. Head-mounted displays using AR technology allow people to view their surroundings while virtual images are projected onto their eyes, holding significant importance in fields such as military, industry, entertainment, medicine, and transportation.

[0003] Currently, the main technologies used in transmissive head-mounted displays for augmented reality include Birdbath, prisms, freeform surfaces, and optical waveguides. Compared to other technologies, head-mounted displays using optical waveguide technology are smaller and more like a pair of glasses. Optical waveguide technology mainly includes arrayed waveguides, surface-embossed grating waveguides, and volume holographic waveguides. Among these, arrayed waveguides outperform diffractive waveguides and volume holographic waveguides in terms of color performance and light energy utilization. In particular, arrayed waveguides using two-dimensional exit pupil expansion technology also have advantages such as small coupling optical engine size, large exit pupil distance, and large eye box size.

[0004] As people's demands for immersive experiences and the aesthetics of AR glasses increase, engineers need to increase the field of view of display systems while maintaining a shape and volume similar to ordinary glasses. Due to its inherent asymmetry, existing two-dimensional waveguide array technology, when using common low-refractive-index materials (e.g., H-BAK5, n=1.56), will result in a field of view of no more than 50° for a reasonably designed product. Using high-refractive-index materials significantly increases the processing difficulty and cost of the two-dimensional waveguide sheet without altering its inherent asymmetry, leading to the same issue of increased volume when transmitting larger field of view. Furthermore, because the bends in traditional two-dimensional waveguide arrays do not display images, the effective display area is centered in the lower middle region of the waveguide sheet, significantly deviating from the optimal position for the human eye. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a symmetrical pupil dilation device and a near-eye display device.

[0006] The technical solution of the present invention is as follows:

[0007] This invention provides a symmetrical pupil dilation device, comprising:

[0008] The first waveguide sheet includes a first waveguide structure and a first coupling structure arranged sequentially along a first direction. The first waveguide structure includes a first steering mirror and a first bending structure arranged sequentially along a second direction. The first bending structure includes a plurality of first beam splitters that are parallel to each other.

[0009] The second waveguide sheet includes a second waveguide structure and a second coupling structure arranged sequentially along a first direction. The second waveguide structure includes a second steering mirror and a second turning structure arranged sequentially along a third direction. The second turning structure includes a plurality of mutually parallel second beam splitters.

[0010] The second waveguide sheet is parallel to and stacked with the first waveguide sheet, and the first steering mirror is corresponding to the second steering mirror. The first waveguide structure and the second waveguide structure are mirror symmetrical. The steering reflection slope of the first steering mirror is parallel to the first beam splitter. The steering reflection slope of the second steering mirror is parallel to the second beam splitter. The second direction is parallel to the third direction and opposite in direction. The first direction is perpendicular to the second direction and / or the third direction.

[0011] An adhesive layer is disposed between the first waveguide sheet and the second waveguide sheet;

[0012] A geometrically coupled prism is disposed in the middle region between the first and second bend structures. The projection surface of the geometrically coupled structure facing the second direction is a quadrilateral, including opposite light-incident edges and light-outcrystal edges, as well as opposite first and second side edges. The light-incident edge and the first side edge form an acute angle θ, where acute angle θ = 60°-80°, and the first side edge is perpendicular to the light-outcrystal edge.

[0013] As a preferred technical solution, the thickness of the first waveguide sheet may be the same as or different from the thickness of the second waveguide sheet.

[0014] As a preferred technical solution, the second side and the light-incident surface form a first angle, and the second side and the light-outceasing surface form a second angle, wherein the first angle and the second angle may be the same or different.

[0015] As a preferred technical solution, multiple first beam splitters are arranged at equal intervals and tilted at an angle α with respect to the second direction, where the tilt angle α = 40°-50°; multiple second beam splitters are arranged at equal intervals and tilted at an angle β with respect to the third direction, where the tilt angles α and β are the same in magnitude but opposite in direction.

[0016] As a preferred technical solution, the first coupling structure includes a plurality of third beam splitters arranged at equal intervals along the first direction; the second coupling structure includes a plurality of fourth beam splitters arranged at equal intervals along the first direction, wherein the first coupling structure and the second coupling structure are correspondingly arranged, and the number of third beam splitters and fourth beam splitters is the same.

[0017] As a preferred technical solution, the geometric coupling prism is a quadrangular prism; both the first steering mirror and the first steering mirror are triangular prisms or quadrangular prisms.

[0018] As a preferred technical solution, the first waveguide structure further includes a first compensation plate and a second compensation plate; the first compensation plate is correspondingly arranged with the second bend structure, and the second compensation plate is correspondingly arranged with the first bend structure.

[0019] As a preferred technical solution, an adhesive layer is provided between the first waveguide sheet and the second waveguide sheet, satisfying the following first formula:

[0020]

[0021] Among them, the third and fourth beam splitters are both at an angle ω to the first direction; 0≤μ≤40°; the refractive index n of the first and second waveguide plates... W The refractive index n of the adhesive layer G The thickness of the adhesive layer is 0.5-5μm.

[0022] As a preferred technical solution, an adhesive layer is provided between the first waveguide sheet and the second waveguide sheet, and a magnesium fluoride coating is provided between the first waveguide sheet and the adhesive layer, and between the second waveguide sheet and the adhesive layer, satisfying the following second formula:

[0023]

[0024] Among them, the third and fourth beam splitters are both at an angle ω to the first direction; 0≤μ≤40°; the refractive index n of the first and second waveguide plates... W The refractive index n of the magnesium fluoride coating C The adhesive layer thickness is 0.5-5μm; the magnesium fluoride coating thickness is 80-500nm.

[0025] The present invention also provides a near-eye display device, including the above-described symmetrical pupil dilator.

[0026] The beneficial effects achieved by the technical solution adopted in this invention are as follows:

[0027] This specification proposes a symmetrical pupil expansion device, comprising a mirror-symmetrical first waveguide plate and second waveguide plate, and a geometric coupling prism. Compared with traditional waveguide schemes, it has mirror symmetry in shape and structure. Light energy is evenly distributed to the first and second waveguide plates through the geometric coupling prism, thus the light energy has symmetry, and the field of view output through the first and second waveguide plates also has symmetry. This device can effectively achieve a large field of view and has high light energy utilization. Most importantly, the height of the transition structure in the first and second waveguide plates only needs to meet the transmission of half of the field of view to achieve full field of view display, which helps to reduce the manufacturing difficulty and reduce the volume of the two-dimensional array waveguide. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below, forming part of the present invention. The illustrative embodiments of the present invention and their descriptions explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 This is a schematic diagram of the symmetrical pupil dilator structure disclosed in this embodiment;

[0030] Figure 2 This is a front view of the symmetrical pupil dilator disclosed in this embodiment;

[0031] Figure 3 This is a side view of the symmetrical pupil dilator disclosed in this embodiment;

[0032] Figure 4 This is a schematic diagram of the symmetrical pupil dilator structure disclosed in this embodiment.

[0033] Explanation of reference numerals in the attached figures:

[0034] First waveguide 100; first bend structure 101; first coupling structure 102; first steering mirror 103; first compensation plate 104; second waveguide 200; second bend structure 201; second coupling structure 202; second steering mirror 203; second compensation plate 204; geometric coupling prism 300; adhesive layer 301; composite waveguide 400. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. In the description of this invention, it should be noted that the term "or" is generally used to include the meaning of "and / or," unless otherwise expressly indicated.

[0036] In the description of this invention, it should be understood that terms such as "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, terms such as "connected" or "linked" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a mechanical connection or an electrical connection; it can refer to a direct connection or an indirect connection through a medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] Furthermore, those skilled in the art should understand that in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on this invention.

[0038] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0039] Example

[0040] according to Figures 1-4 This embodiment provides a symmetrical pupil dilator, including:

[0041] The first waveguide sheet 100 includes a first waveguide structure and a first coupling structure 102 arranged sequentially along a first direction. The first waveguide structure includes a first steering mirror and a first bending structure 101 arranged sequentially along a second direction. The first bending structure 101 includes a plurality of first beam splitters that are parallel to each other.

[0042] The second waveguide 200 includes a second waveguide structure and a second coupling structure 202 arranged sequentially along a first direction. The second waveguide structure includes a second steering mirror 203 and a second bending structure 201 arranged sequentially along a third direction. The first bending structure 101 includes a plurality of mutually parallel second beam splitters.

[0043] The second waveguide plate 200 is parallel to and stacked with the first waveguide plate 100, and the first steering mirror and the second steering mirror 203 are correspondingly arranged; the first waveguide structure and the second waveguide structure are mirror-symmetrical; the steering reflection slope of the first steering mirror 103 is parallel to the first beam splitter; the steering reflection slope of the second steering mirror 203 is parallel to the second beam splitter; the second direction is parallel to the third direction and opposite in direction, and the first direction is perpendicular to the second direction and / or the third direction.

[0044] An adhesive layer 301 is disposed between the first waveguide sheet 100 and the second waveguide sheet 200;

[0045] The geometric coupling prism 300 is disposed in the middle region between the first turning structure 101 and the second turning structure 201. The projection surface of the geometric coupling structure facing the second direction is quadrilateral, including opposite light-incident edges and light-outcident edges, as well as opposite first and second side edges. The light-incident edge and the first side edge form an acute angle θ, where acute angle θ = 60°-80°, and the first side edge is perpendicular to the light-outcident edge.

[0046] Based on the asymmetric structural characteristics and limited field of view of existing single-layer two-dimensional array waveguides, this embodiment proposes a symmetrical pupil expansion device, including a mirror-symmetrical first waveguide plate 100 and second waveguide plate 200 and a geometric coupling prism 300. Compared with traditional waveguide schemes, it has mirror symmetry in shape and structure. Light energy is evenly distributed to the first waveguide plate 100 and the second waveguide plate 200 through the geometric coupling prism 300, so the light energy has symmetry, and the field of view output by the first waveguide plate 100 and the second waveguide plate 200 also has symmetry. This device can effectively achieve a large field of view and has high light energy utilization. Most importantly, the height of the turning structure in the first waveguide plate 100 and the second waveguide plate 200 only needs to meet the transmission of half of the field of view to achieve full field of view display, which helps to reduce the manufacturing difficulty and reduce the volume of the two-dimensional array waveguide.

[0047] Preferably, the thickness of the first waveguide sheet 100 is the same as or different from the thickness of the second waveguide sheet 200.

[0048] Preferably, the second side is at a first angle to the incident light surface and at a second angle to the emitting light surface, and the first angle and the second angle may be the same or different.

[0049] For details, see Figures 1-4 The first waveguide sheet 100 includes a first waveguide structure and a first coupling structure 102 arranged sequentially along a first direction. The first waveguide structure includes a first steering mirror 103 and a first turning structure 101 arranged sequentially along a second direction. The second waveguide sheet 200 includes a second waveguide structure and a second coupling structure 202 arranged sequentially along the first direction. The second waveguide structure includes a second steering mirror 203 and a second turning structure 201 arranged sequentially along a third direction. In short, the first waveguide sheet 100 and the second waveguide sheet 200 are two two-dimensional array waveguide sheets that are mirror-symmetrical. Preferably, the first waveguide sheet 100 and the second waveguide sheet 200 have the same size, and the number of the first beam splitter and the second beam splitter is the same, preferably 5-8. The process is simple and easy to operate, and the bonded waveguide has strong symmetry in both structure and optical effect. It should be noted that the first and second beam splitters shown in the accompanying drawings are only schematic and are not intended to limit the embodiments of the present invention. In specific implementations, the number of beam splitters can be designed according to actual conditions.

[0050] The first waveguide sheet 100 and the second waveguide sheet 200 are laminated and bonded together to form a composite waveguide sheet 400, see Figure 4 Overall, the first coupling structure 102 and the second coupling structure 202 are set in a corresponding manner, the first turning structure 101 and the second turning structure 201 are mirror symmetrical, and the turning reflective surface of the first turning mirror 103 and the turning reflective surface of the second turning mirror 203 intersect.

[0051] Taking the second waveguide 200 in front of the first waveguide 100 as an example, a geometric coupling prism 300 is provided in the middle region between the first bending structure and the second bending structure 201. The geometric coupling prism 300 is preferably a quadrangular prism, and its projection in the second direction is a quadrilateral, including opposite light-incident edges and light-outcrystal edges, as well as opposite first side edges and second side edges. The light-incident edge and the first side edge are set at an acute angle θ, where acute angle θ = 60°-80°.

[0052] Furthermore, viewed from the projection in the second direction, the first side and the substrate outside the first waveguide 100 are parallel and on the same straight line, and the first side is perpendicular to the light-emitting edge. Figure 3 In this embodiment, the first angle between the light-incident edge and the second side, and the second angle between the light-outcident edge and the second side, are preferably both obtuse angles. The specific angles can be set by those skilled in the art according to the requirements of this structure. Preferably, the acute angle θ of the geometric coupling prism 300 is 70°. The angles of the first and second angles are different. This composite waveguide 400 has strong symmetry. Combined with the large-angle geometric coupling prism 300, it can easily realize the transmission and display of images with a large field of view.

[0053] This configuration allows the optical engine to emit a parallel beam carrying virtual image information, which is perpendicularly incident on the geometric coupling prism 300 via the incident surface. Half of the light is redirected by the first deflecting prism and incident into the first waveguide plate 100 (i.e., the first beam), while the other half is redirected by the second deflecting prism and incident into the second waveguide plate 200 (i.e., the second beam). In other words, the energy of the incident beam is equal to the sum of the energies of the first and second beams, and the energy of the first beam is equal to the energy of the second beam, resulting in no energy loss and no loss of brightness uniformity, thus achieving higher light energy utilization. A schematic diagram illustrating the propagation of a beam divided into a first and second beam is provided below for clarity. Figure 4 Arrows are used to illustrate the general trend of light; the specific direction will vary depending on the actual situation.

[0054] Since the first beam of light is incident on the first waveguide 100 and undergoes total internal reflection transmission, and is output to the human eye position, it has a first field of view; the second beam of light is incident on the second waveguide 200 and undergoes total internal reflection transmission, and is output to the human eye position, it has a second field of view. The first beam of light and the second beam of light are mirror symmetrical and have the same light energy. In a preferred embodiment, the image light energy ratio of the first waveguide 100 and the first waveguide 100 can also be adjusted by setting the thickness ratio of the first waveguide 100 and the first waveguide 100, which can effectively achieve the adjustment of the brightness uniformity of the first field of view and the second field of view.

[0055] Preferably, a plurality of first beam splitters are arranged at equal intervals and at an angle α to the second direction, the angle α being 40°-50°; a plurality of second beam splitters are arranged at equal intervals and at an angle β to the third direction, the angles α and β being the same in magnitude but opposite in direction.

[0056] Preferably, the first coupling structure 102 includes a plurality of third beam splitters arranged at equal intervals along the first direction, and the third beam splitters are parallel to the second direction and / or the third direction; the second coupling structure 202 includes a plurality of fourth beam splitters arranged at equal intervals along the first direction, and the fourth beam splitters are parallel to the second direction and / or the third direction; and the first coupling structure 102 and the second coupling structure 202 are correspondingly arranged, and the number of third beam splitters is the same.

[0057] Specifically, both the first waveguide 100 and the second waveguide 200 are two-dimensional array waveguide structures, meaning they both include a bend structure and a coupling structure. The first bend structure 101 and the first coupling structure 102 in the first waveguide 100 are specifically composed of multiple first beam splitters arranged at an angle α and at equal intervals along a second direction. These beam splitters are used to expand the pupil of the first beam along the second direction and change the transmission direction of the first beam, causing the reflected first beam to propagate towards the direction of the first coupling structure 102. Multiple third beam splitters are arranged at equal intervals along a first direction and are parallel to the second direction and / or the third direction. These beam splitters are used to further expand the pupil of the first beam output from the first bend structure 101 in the first direction, and after coupling out of the waveguide, project onto the human eye located at the exit pupil position for imaging.

[0058] The second bend structure 201 and the second coupling structure 202 in the second waveguide sheet 200 specifically consist of multiple second beam splitters at an angle β and equally spaced along a third direction, used to expand the pupil of the second beam along the third direction; multiple fourth beam splitters are equally spaced along a first direction and parallel to the second direction and / or the third direction, used to expand the pupil of the second beam output from the second bend structure 201 again in the first direction. Preferably, α=β=45°, and the symmetry of the bonded waveguide structure, as well as the uniformity of light energy distribution, light beam symmetry, and field-of-view symmetry are all stronger.

[0059] The first beam of light, expanded by the first coupling structure 102, forms the first field of view, and the second beam of light, expanded by the second coupling structure 202, forms the second field of view. The first and second field of view are symmetrical. When the human eye observes, it simultaneously receives the image light from the first waveguide 100 and the image light from the first waveguide 100. The two half-field images are then combined into a complete field of view image.

[0060] Compared to traditional two-dimensional waveguide sheets, where the height of the transition structure must satisfy the transmission of the entire field of view to display a complete image, the height of the transition structure of the first waveguide sheet 100 and the second waveguide sheet 200 in this embodiment, i.e., the height along the first direction, only needs to satisfy the transmission of half the field of view to achieve full-field-of-view display. This effectively achieves a large field of view, significantly reduces the volume of the two-dimensional array waveguide, and lowers the actual manufacturing difficulty. Figure 4 .

[0061] It should be noted that the third and fourth beam splitters shown in the accompanying drawings are merely schematic and are not intended to limit the embodiments of the present invention. In specific implementations, the number of beam splitters can be designed according to actual conditions.

[0062] Preferably, both the first steering mirror 103 and the second steering mirror 203 are triangular prisms or quadrangular prisms.

[0063] Specifically, the first steering mirror 103 and the second steering mirror 203 are preferably triangular prisms or quadrangular prisms. Taking a triangular prism as an example, a regular triangular prism is preferred, with the inclined surface of the regular triangular prism serving as the steering reflector. The projections of the first steering mirror 103 and the second steering mirror 203 along the fourth direction are both right-angled triangles. The right-angled triangle projected by the first steering mirror 103 includes two first right-angled sides and a first hypotenuse, while the right-angled triangle projected by the second steering mirror 203 includes two second right-angled sides and a second hypotenuse. The first hypotenuse is parallel to the first beam splitter, and the second hypotenuse is parallel to the second beam splitter, meaning the first hypotenuse intersects the second inclined surface. The angle between the first hypotenuse and the second direction is α, preferably α = 45°; the angle between the second hypotenuse and the third direction is β, preferably α = 45°. If both the first steering mirror 103 and the second steering mirror are quadrangular prisms, it is equivalent to splicing the two regular triangular prisms together to form a quadrangular prism, with the splicing position serving as the steering reflector. Using a quadrangular prism provides better stability.

[0064] The placement of the first steering mirror 103 and the second steering mirror 203 can be referenced. Figures 1-2 The given placement position is such that when a beam of parallel light emitted from the optical engine is coupled into the first waveguide 100 by the first turning prism after being coupled into the second waveguide 200 by the second turning prism, half of the light beam is turned into the second waveguide 200 by the first turning prism and the other half of the light beam is turned into the second waveguide 200 by the second turning prism. The fourth direction is perpendicular to the first direction, the second direction and the third direction.

[0065] Preferably, the first waveguide structure further includes a first compensation plate 104 and a second compensation plate 204; the first compensation plate 104 is correspondingly disposed with the second bend structure 201, and the second compensation plate 204 is correspondingly disposed with the first bend structure 101.

[0066] Specifically, the first waveguide structure also includes a first compensation plate 104, which is positioned close to the first steering prism. The second waveguide structure also includes a second compensation plate 204, which is positioned close to the second steering prism. After the first waveguide sheet 100 and the second waveguide sheet 200 are glued together, the first compensation plate 104 is positioned corresponding to the second turning structure 201, and the second compensation plate 204 is positioned corresponding to the first turning structure 101. This helps to make the overall waveguide structure more stable and the support force more balanced.

[0067] In this embodiment, the geometric coupling prism 300, the first steering mirror 103, the second steering mirror 203, the first compensation plate 104, and the second compensation plate 204 are all preferably made of glass. In this embodiment, the waveguide substrate and the geometric coupling prism 300, the first steering mirror 103, the second steering mirror 203, the first compensation plate 104, and the second compensation plate 204 are made of the same material. The same material ensures that the waveguide substrate and the prism have the same optical performance, which ensures that the light can propagate in a straight line in the optical waveguide assembly and ensures the imaging quality.

[0068] Preferably, an adhesive layer 301 is provided between the first waveguide sheet 100 and the second waveguide sheet 200, satisfying the following first formula:

[0069]

[0070] The third and fourth beam splitters are both at an angle ω to the first direction; 0 ≤ μ ≤ 40°; the refractive index n of the first waveguide 100 and the second waveguide 200 is... W The refractive index n of the adhesive layer 301 G .

[0071] Preferably, an adhesive layer 301 is provided between the first waveguide sheet 100 and the second waveguide sheet 200, and a magnesium fluoride coating is provided between the first waveguide sheet 100 and the adhesive layer 301, and between the second waveguide sheet 200 and the adhesive layer 301, satisfying the following second formula:

[0072]

[0073] The third and fourth beam splitters are both at an angle ω to the first direction; 0 ≤ μ ≤ 40°; the refractive index n of the first waveguide 100 and the second waveguide 200 is... W The refractive index n of the magnesium fluoride coating C .

[0074] Specifically, the first waveguide 100 and the second waveguide 200 need to be strictly sealed without any gaps, meaning no air can enter, to ensure stable light transmission within the composite waveguide 400 and no light energy loss. In this embodiment, a preferred adhesive layer 301 is used, resulting in two specific structures. One is where the adhesive layer 301 is located between the first waveguide 100 and the second waveguide 200, satisfying the following first relationship:

[0075]

[0076] Another configuration has an adhesive layer 301 located between the first waveguide sheet 100 and the second waveguide sheet 200, with a magnesium fluoride coating provided between the first waveguide sheet 100 and the adhesive layer 301, and between the second waveguide sheet 200 and the adhesive layer 301, satisfying the following second relationship:

[0077]

[0078] Preferably, the adhesive layer 301 has a thickness of 0.5-5 μm, which allows the first waveguide structure to be tightly bonded together with each other, and the first coupling structure 102 to the second coupling structure 202, resulting in high structural strength. The adhesive layer 301 can be an optical adhesive, or other transparent colloids that satisfy the first and second relationships described above, without specific limitations.

[0079] Preferably, the magnesium fluoride coating thickness is 80-500 nm. In actual operation, the magnesium fluoride coating can be uniformly applied to the surfaces of the first waveguide 100 and the second waveguide 200 to be bonded first. Then, the bonding layer 301 is applied to the surface of the first waveguide 100 or the second waveguide 200 with the magnesium fluoride coating applied. Finally, the side of the second waveguide 100 with the magnesium fluoride coating is bonded together. The specific process can be set according to actual needs and is not specifically limited here. The design of the magnesium fluoride coating avoids light transmission disorder and ensures that light can be stably transmitted by total internal reflection within the first waveguide 100 or the second waveguide 200, improving the stability of the displayed image. The magnesium fluoride coating can also be replaced with other transparent coatings with good optical properties such as good density, as long as the second relational expression is satisfied.

[0080] This embodiment also provides a near-eye display device, including the aforementioned symmetrical pupil expansion device, which has strong symmetry. The height of the turning structure only needs to meet the transmission of half of the field of view to achieve full-field display. It has high light energy utilization, small size, and reduced manufacturing difficulty.

[0081] The foregoing has provided a detailed description of a symmetrical pupil-expanding device and a near-eye display device according to embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A symmetrical pupillary dilation device, comprising: include: The first waveguide sheet includes a first waveguide structure and a first coupling structure arranged sequentially along a first direction. The first waveguide structure includes a first steering mirror and a first bending structure arranged sequentially along a second direction. The first bending structure includes a plurality of mutually parallel first beam splitters. The second waveguide sheet includes a second waveguide structure and a second coupling structure arranged sequentially along a first direction. The second waveguide structure includes a second steering mirror and a second turning structure arranged sequentially along a third direction. The second turning structure includes a plurality of mutually parallel second beam splitters. Wherein, the second waveguide sheet and the first waveguide sheet are arranged parallel to each other and stacked, and the first steering mirror and the second steering mirror are arranged correspondingly. The first waveguide structure and the second waveguide structure are mirror-symmetrical. The steering reflection slope of the first steering mirror is parallel to the first beam splitter. The steering reflection slope of the second steering mirror is parallel to the second beam splitter. The second direction is parallel to the third direction and opposite in direction. The first direction is perpendicular to the second direction and / or the third direction. An adhesive layer is disposed between the first waveguide sheet and the second waveguide sheet; the first waveguide sheet and the second waveguide sheet have a thickness ratio, and the thickness of the first waveguide sheet is the same as the thickness of the second waveguide sheet; A geometric coupling prism is disposed in the middle region between the first and second turning structures. The geometric coupling prism is a quadrangular prism, and the projection surface of the geometric coupling structure facing the second direction is a quadrilateral, including opposing light-incident edges and light-outcrystal edges, as well as opposing first and second side edges. The light-incident edge forms an acute angle θ with the first side edge, where the acute angle θ = 70°. The first side edge is parallel to the substrate outside the first waveguide sheet and lies on the same straight line, and the first side edge is perpendicular to the light-outcrystal edge. There is a first included angle between the light-incident edge and the second side edge, and a second included angle between the light-outcrystal edge and the second side edge. Both the first and second included angles are obtuse angles. This allows a beam of light carrying virtual image information that is perpendicularly incident through the light-incident surface to be split into a first beam of light and a second beam of light with the same energy. The first beam of light is turned by the first turning mirror and incident into the first waveguide sheet, and the second beam of light is turned by the second turning mirror and incident into the second waveguide sheet.

2. The symmetrical pupil dilator according to claim 1, characterized in that, The second side forms a first angle with the light-incident surface and a second angle with the light-outceasing surface, wherein the first angle and the second angle may be the same or different.

3. The symmetrical pupil dilator according to claim 1, characterized in that, Multiple first beam splitters are arranged at equal intervals and tilted at an angle α to the second direction, wherein the tilt angle α = 40°-50°; multiple second beam splitters are arranged at equal intervals and tilted at an angle β to the third direction, wherein the tilt angle α and the tilt angle β are the same in magnitude but opposite in direction.

4. The symmetrical pupil dilator according to claim 3, characterized in that, The first coupling structure includes a plurality of third beam splitters arranged at equal intervals along the first direction; the second coupling structure includes a plurality of fourth beam splitters arranged at equal intervals along the first direction, wherein the first coupling structure and the second coupling structure are correspondingly arranged, and the number of the third beam splitters and the number of the fourth beam splitters are the same.

5. The symmetrical pupil dilator according to claim 4, characterized in that, Both the first steering mirror and the first steering mirror are triangular prisms or quadrangular prisms.

6. The symmetrical pupil dilator according to claim 5, characterized in that, The first waveguide structure further includes a first compensation plate and a second compensation plate; the first compensation plate is correspondingly arranged with the second bend structure and the second compensation plate is correspondingly arranged with the first bend structure.

7. The symmetrical pupil dilator according to any one of claims 1-6, characterized in that, An adhesive layer is provided between the first waveguide sheet and the second waveguide sheet, satisfying the following first formula: The third and fourth beam splitters are both at an angle ω to the first direction; 0 ≤ μ ≤ 40°; the refractive index n of the first and second waveguides is... W The refractive index n of the adhesive layer G The thickness of the adhesive layer is 0.5-5 μm.

8. The symmetrical pupil dilator according to any one of claims 1-6, characterized in that, An adhesive layer is provided between the first waveguide sheet and the second waveguide sheet, and a magnesium fluoride coating is provided between the first waveguide sheet and the adhesive layer, and between the second waveguide sheet and the adhesive layer, satisfying the following second formula: The third and fourth beam splitters are both at an angle ω to the first direction; 0 ≤ μ ≤ 40°; the refractive index n of the first and second waveguides is... W The refractive index n of the magnesium fluoride coating C The adhesive layer has a thickness of 0.5-5 μm; the magnesium fluoride coating has a thickness of 80-500 nm.

9. A near-eye display device, characterized in that, Includes the symmetrical pupil dilator as described in any one of claims 1-8.

Images