Optical waveguide structure and near-to-eye display equipment

Abstract

The invention relates to an optical waveguide structure and near-to-eye display equipment, the structure comprises a light guide plate, a coupling-in prism, a polarization beam splitting film, a pupil expansion beam splitting film and a coupling-out array beam splitting film are sequentially arranged in the light guide plate at least in the light path transmission direction, the coupling-in prism is arranged in a coupling-in area of the light guide plate and used for enabling incident light to be coupled into the light guide plate, and the coupling-out array beam splitting film is arranged in a coupling-out area of the light guide plate and used for enabling incident light to enter the light guide plate. The polarization beam-splitting film comprises at least 2N S-transmitting and P-reflecting films which are embedded in the light guide plate and are obliquely arranged, N is larger than or equal to 1, and every two adjacent S-transmitting and P-reflecting films are in mirror symmetry; the pupil-expanding light-splitting film is embedded in the middle of the thickness of the light guide plate and is parallel to the plane of the light guide plate, and the polarization light-splitting film is arranged close to the pupil-expanding light-splitting film; the coupled-out array light splitting film comprises a plurality of light splitting films which are arranged in an inclined mode and embedded in the light guide plate, the pupil expanding light splitting film is arranged close to the coupled-out array light splitting film, and the higher brightness uniformity effect is achieved with the lower process cost.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and in particular to an optical waveguide structure and a near-eye display device. Background Technology

[0002] Traditional arrayed waveguides typically include a coupling prism, a light guide plate, and an array beam splitter within the light guide plate. Incident light is coupled into the light guide plate via the coupling prism and undergoes total internal reflection before exiting through the array beam splitter and entering the human eye. However, the incident light is a mixed polarized light with both P- and S-polarizations. The beam splitter must simultaneously match the optical characteristics of both polarization states. Since the reflection and transmission patterns of S- and P-polarizations at the film interface are significantly different, the coating process struggles to achieve precise control of the beam splitting ratio, directly leading to poor brightness uniformity in the waveguide's output region. To adapt to the mixed polarization states, the beam splitter design becomes more complex and requires extremely high coating precision, resulting in high production difficulty, low yield, and high cost. Summary of the Invention

[0003] In view of the problems existing in the prior art, the present invention provides an optical waveguide structure and a near-eye display device.

[0004] The technical solution of the present invention is as follows:

[0005] This application provides an optical waveguide structure, including:

[0006] The light guide plate includes at least a coupling prism, a polarizing beam splitter, a pupil-expanding beam splitter, and an output beam splitter array arranged sequentially along the optical path transmission direction.

[0007] A coupling prism, located in the coupling area of ​​the light guide plate, is used to couple incident light into the light guide plate; a polarizing beam splitter includes at least 2N transparent S-reflective P-films, N≥1, which are embedded in the light guide plate and arranged at an angle, and two adjacent transparent S-reflective P-films are mirror-symmetrical; a pupil-expanding beam splitter is embedded in the middle of the thickness of the light guide plate and is parallel to the plane of the light guide plate, with the polarizing beam splitter adjacent to the pupil-expanding beam splitter; and a coupling array beam splitter is located adjacent to the pupil-expanding beam splitter.

[0008] As a preferred technical solution, the output image field of view is set to Fov, the horizontal to vertical ratio is p:q, and the refractive index of the light guide plate is n. Therefore, the light guide plate has a horizontal half-field of view Fov in air. h Satisfy: Fov h = When light propagates inside the light guide plate, the total internal reflection angle α satisfies: .

[0009] As a preferred technical solution, the coupling prism is a triangular prism, and the incident angle formed by the incident surface and the reflecting surface of the triangular prism is... θ =65°-75°.

[0010] As a preferred technical solution, two adjacent transparent S-reflective P films and one plane of the light guide plate form an isosceles triangle, and the base angle β of the isosceles triangle satisfies: β = θ -45° is used to filter out S-polarized light for total internal reflection transmission within the light guide plate.

[0011] As a preferred technical solution, the pupil-expanding beam-splitting film is a semi-transparent and semi-reflective film, embedded at half the thickness of the light guide plate, and the length L of the pupil-expanding beam-splitting film = .

[0012] As a preferred technical solution, the distance between the polarizing beam splitter and the coupling prism is not less than L.

[0013] As a preferred technical solution, the coupled array beam splitter includes multiple beam splitters embedded in a light guide plate. These multiple beam splitters are arranged at equal intervals and are tilted at an angle γ to the plane of the light guide plate, where the tilt angle γ = .

[0014] As a preferred technical solution, the polarization beam splitter includes two transparent S-reflective P-films, which are connected end to end and are mirror-symmetrical.

[0015] As a preferred technical solution, the polarization beam splitter includes 2N transparent S-reflective P-films, where N≥2. The multiple transparent S-reflective P-films are connected end to end, and two adjacent transparent S-reflective P-films are mirror-symmetrical, or adjacent transparent S-reflective P-films are connected end to end and are mirror-symmetrical to form multiple transparent S-reflective P-film groups, and the multiple transparent S-reflective P-film groups are arranged at equal intervals.

[0016] This application also provides a near-eye display device, including the aforementioned optical waveguide structure.

[0017] The beneficial effects achieved by the technical solution adopted in this invention are as follows:

[0018] This invention provides an optical waveguide structure and a near-eye display device, comprising a light guide plate. The light guide plate includes at least a coupling prism, a polarizing beam splitter, a pupil-expanding beam splitter, and a coupling array beam splitter sequentially arranged along the optical path transmission direction of the light guide plate. The coupling prism is located in the coupling region of the light guide plate to couple incident light into the light guide plate. The polarizing beam splitter includes at least 2N transmissive S-reflective P-films, where N≥1, embedded within the light guide plate and arranged obliquely. Adjacent transmissive S-reflective P-films are mirror-symmetrical, used to split the mixed polarized light coupled into the light guide plate. The single polarization state of S-beams is selected; the pupil-expanding beam splitter is embedded in the middle of the light guide plate thickness and parallel to the plane of the light guide plate, so as to replicate the single polarization state of S-beams and fill the entire entrance pupil of the light guide plate; the coupling array beam splitter is used to reflect the uniformly distributed S-polarized light in the waveguide out of the waveguide and project it to the human eye to form a display image with good brightness uniformity. In this solution, the pupil-expanding beam splitter and the coupling array beam splitter only need to be designed for the characteristics of S-beams, simplifying the film system design, greatly reducing the process difficulty, low cost, and high product yield. Attached Figure Description

[0019] 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:

[0020] Figure 1 This is a schematic diagram of the optical waveguide structure disclosed in this embodiment;

[0021] Figure 2 This is a schematic diagram of the optical waveguide structure disclosed in this embodiment.

[0022] Explanation of reference numerals in the attached figures:

[0023] Light guide plate 10; coupling prism 11; first transparent S-reflective P film 12; second transparent S-reflective P film 13; pupil dilator beam splitter 14; coupling array beam splitter 15. Detailed Implementation

[0024] 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.

[0025] In the description of this invention, it should be understood that the terms "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, the terms "connected" or "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they 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.

[0026] 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.

[0027] 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.

[0028] Example

[0029] To address the issues of uneven brightness and difficult coating processes caused by mixed polarization light in existing array waveguide solutions, based on... Figure 1 This embodiment provides an optical waveguide structure, comprising:

[0030] The light guide plate 10 includes at least a coupling prism 11, a polarizing beam splitter, a pupil-expanding beam splitter 14, and a coupling array beam splitter 15 arranged sequentially along the optical path transmission direction.

[0031] A coupling prism 11 is disposed in the coupling area of ​​the light guide plate 10 to couple incident light into the light guide plate 10; a polarizing beam splitter includes at least 2N transparent S-reflective P-films embedded in the light guide plate 10 at an angle, where N≥1, N is a positive integer, and two adjacent transparent S-reflective P-films are mirror-symmetrical; a pupil-expanding beam splitter 14 is embedded in the middle of the thickness of the light guide plate 10 and is parallel to the plane of the light guide plate 10, with the polarizing beam splitter adjacent to the pupil-expanding beam splitter 14; and a coupling array beam splitter 15 is disposed adjacent to the coupling array beam splitter 15.

[0032] This embodiment proposes an optical waveguide structure, including a light guide plate 10. The light guide plate 10 includes at least a coupling prism 11, a polarizing beam splitter, a pupil-expanding beam splitter 14, and a coupling array beam splitter 15 arranged sequentially along the optical path transmission direction of the light guide plate 10. The coupling prism 11 is disposed in the coupling region of the light guide plate 10 to couple incident light into the light guide plate 10. The polarizing beam splitter includes at least 2N transparent S-reflective P-films, where N≥1, embedded in the light guide plate 10 and arranged at an angle. Two adjacent transparent S-reflective P-films are mirror-symmetrical to split the mixed polarization coupled into the light guide plate 10. The light filters out S-beams with a single polarization state; the pupil-expanding beam splitter 14 is embedded in the middle of the thickness of the light guide plate 10 and is parallel to the plane of the light guide plate 10, so as to replicate the S-beams with a single polarization state and fill the entire entrance pupil of the light guide plate 10; the coupling array beam splitter 15 is used to reflect the S-polarized light uniformly distributed in the waveguide out of the waveguide and project it to the human eye to form a display image with good brightness uniformity. In this solution, the pupil-expanding beam splitter 14 and the coupling array beam splitter 15 only need to be designed for the characteristics of S-beams, simplifying the film system design, greatly reducing the difficulty of the process, resulting in low cost and high product yield.

[0033] according to Figure 1 The optical waveguide structure shown includes a light guide plate 10. The light guide plate 10 includes at least a coupling prism 11, a polarizing beam splitter, a pupil-expanding beam splitter 14, and an output array beam splitter 15 arranged sequentially in the optical path transmission direction. It can be understood that the light guide plate 10 is the main body of the optical waveguide structure, which includes two parallel upper and lower surfaces. Light is transmitted through total internal reflection between the upper and lower surfaces of the light guide plate 10. The material can be transparent optical glass or optical resin. The coupling prism 11 is disposed in the coupling area of ​​the light guide plate 10. The two can be tightly connected by an optical adhesive layer or direct contact to form a seamless optical channel. For example, direct contact can be a bond connection to form a seamless optical channel without interface gaps and without loss, ensuring efficient coupling and stable transmission of light. The polarizing beam splitter, the pupil-expanding beam splitter 14, and the output array beam splitter 15 are disposed between the upper and lower surfaces of the light guide plate 10.

[0034] Furthermore, the coupling prism 11 is a triangular prism. Since the coupling area of ​​the light guide plate 10 is located at one end of the light guide plate 10, the triangular prism is located at one end of the light guide plate 10. The coupling prism 11 is preferably a right-angled triangular prism, which includes at least an incident surface, a reflecting surface, and an exit surface. The three together form a closed right-angled triangular prism optical cavity. The exit surface is fixedly connected to the coupling area of ​​the light guide plate 10. The exit surface is perpendicular to the reflecting surface, and the angle formed by the incident surface and the reflecting surface is the incident angle. θ Angle of incidence θ It can be around 45°, such as 30°-50°, or it can be a larger angle, preferably the angle of incidence. θ=65°-75°, this angle design can effectively reduce the number of total internal reflection transmissions of light in the light guide plate 10, thereby reducing the cumulative interference of surface shape deviation and parallelism process error of the upper and lower transmission surfaces of the light guide plate 10 on the light transmission path and ensuring transmission stability.

[0035] Furthermore, this optical waveguide structure sets the output image field of view to Fov, the horizontal to vertical ratio to be p:q, and the refractive index of the light guide plate 10 to be n. Therefore, the light guide plate 10 has a horizontal half-field of view Fov in air. h Satisfy: Fov h = When light propagates inside the light guide plate 10, the total internal reflection angle α satisfies: This study clarifies the adaptation logic between the observable field of view and the stable transmission of internal light in waveguide design, providing a quantitative basis for the selection of optical parameters and structural size design of the entire optical waveguide structure. This helps to meet the requirements of complete field of view, stable transmission, and uniform display, so as to obtain devices with better display effects.

[0036] Furthermore, the polarization beam splitter includes two S-polarized and P-polarized films, which are connected end-to-end and mirror-symmetrical. For ease of description, the two S-polarized and P-polarized films are referred to as the first S-polarized and P-polarized film 12 and the second S-polarized and P-polarized film 13. The S-polarized and P-polarized film achieves high transmittance for S-polarized light and high reflectance for P-polarized light in the incident light. Through this film layer, incident light with complex polarization states can be converted into single S-polarized light, eliminating the interference of polarization diversity on subsequent beam splitting. According to Figure 2The left side shows the first transparent S-reflective P-film 12, and the right side shows the second transparent S-reflective P-film 13. The light entering the light guide plate 10 includes at least light ray A and light ray B. Light ray A is incident on the first transparent S-reflective P-film 12 at an angle of less than 45°. This can be understood as the angle between the normal of the first transparent S-reflective P-film 12 and light ray A being less than 45°, easily achieving high S-light transmission and high P-light reflection, meeting the polarization screening requirements and providing the prerequisite for accurate beam splitting of the subsequent pupil-expanding beam splitter 14. When light ray B is incident on the first transparent S-reflective P-film 12 at an angle of 45° or greater, especially much greater than 45°, the polarization response of the optical film layer changes significantly with the angle of incidence. Taking 80° as an example, the screening efficiency of the first transparent S-reflective P-film 12 decreases significantly, and the P component is mixed in, as shown by light ray C in the diagram. In other words, a large angle of incidence disrupts the polarization-selective interference conditions of the film layer, which affects the subsequent coating of the pupil-expanding beam splitter 14. It is impossible for the membrane to achieve beam splitting at both 45°+α and 80°+α simultaneously. Therefore, two transparent S-reflective P-films are set in front of the pupil-expanding beam splitter 14, and the first transparent S-reflective P-film 12 and the second transparent S-reflective P-film 13 are mirror-symmetrical. The second transparent S-reflective P-film 13 is used to compensate for the screening shortcomings of the first transparent S-reflective P-film 12 at large incident angles. It can be understood that the pupil-expanding beam splitter 14 must achieve 50% beam splitting in two large-span incident angle ranges at the same time, which is physically and technologically impossible. When the beam splitting ratio of the pupil-expanding beam splitter 14 deviates from 50%, the intensity of the two pupils in the light guide plate 10 will be inconsistent, and the brightness uniformity of the coupled image will be very poor. Even at the same incident angle, if the pupil-expanding beam splitter 14 has different beam splitting ratios for different wavelengths, the resulting color uniformity will also be extremely poor. Therefore, the coordinated design of the polarizing beam splitter and the pupil-expanding beam splitter 14 helps to improve brightness uniformity and color uniformity.

[0037] The synergistic design of the polarizing beam splitter and the pupil-expanding beam splitter 14 helps reduce dispersion interference and ensure color uniformity, breaking through the limitations of the incident angle and wavelength sensitivity of traditional beam splitters. This is because the wavelength sensitivity of traditional beam splitters mainly stems from the Brewster angle of P-light shifting with wavelength, resulting in significant differences in the splitting ratio of P-light at different wavelengths, ultimately causing color cast. With the polarizing beam splitter and the pupil-expanding beam splitter 14, the filtered single S-light has no Brewster angle effect, and its optical characteristics change linearly with wavelength without abrupt changes, fundamentally avoiding the nonlinear wavelength sensitivity problem caused by P-light. The mirror design of the two transparent S- and reflective P-films of the polarizing beam splitter ensures high transmittance of S-light across the entire wavelength range. The pupil-expanding beam splitter 14 can achieve 50% splitting ratio consistency across the entire wavelength range through a simple multilayer dielectric film design, ultimately outputting an image with consistent color uniformity.

[0038] In a preferred embodiment, the first transparent S-reflective P film 12 and the second transparent S-reflective P film 13 are mirror-symmetrical and connected end-to-end. The first transparent S-reflective P film 12, the second transparent S-reflective P film 13, and the lower surface of the light guide plate 10 form an isosceles triangle, and the base angle β of the isosceles triangle satisfies: β = θ -45° is used to ensure that the transmitted S-light can be transmitted by total internal reflection within the light guide plate 10, so that light with a small incident angle is filtered by the first S-reflection P film 12 and light with a large incident angle is filtered by the second S-reflection P film 13. This ensures that no matter the incident angle, all transmitted light within the light guide plate 10 can be effectively filtered into pure S-light, preventing unfiltered mixed polarized light from entering the subsequent pupil dilatation beam splitter 14.

[0039] Furthermore, since S-polarized light has no Brewster angle abrupt change, its reflection / transmission law is stable. A 50% splitting ratio can be accurately achieved through a simple pupil-expanding beam splitter 14 design, resulting in good uniformity of brightness in the coupled image. The pupil-expanding beam splitter 14 only needs to be designed for single S-polarized light, significantly reducing the difficulty of achieving a 50% splitting ratio and exhibiting extremely high stability. A pupil-expanding beam splitter 14 optimized only for S-polarized light can achieve a consistent splitting ratio within the target wavelength range, with excellent color uniformity. Preferably, the pupil-expanding beam splitter 14 is a semi-transparent, semi-reflective film, embedded at half the thickness of the light guide plate 10, with a length L = This is used to achieve precise 50% beam splitting of the selected S-polarized light. Through at least one reflection and beam splitting, the S-polarized light fills the entire entrance pupil. This ensures that the light intensity distribution is uniform in different areas within the light guide plate 10 after pupil expansion. The polarization beam splitting film is arranged close to the coupling array beam splitting film 15, preferably with the two adjacent to each other in the horizontal direction, i.e., there is no gap between the polarization beam splitting film and the coupling array beam splitting film 15 in the horizontal direction. The selected pure S-light only needs to undergo a very small number of total internal reflections to reach the coupling beam splitting film, effectively avoiding the polarization state evolution during light transmission, i.e., preventing the pure S-light from becoming mixed polarized light again, ensuring the polarization consistency of the entire beam splitting and coupling process. Even for the coupling prism 11 with a large incident angle, it can ensure that the entire entrance pupil is filled and the brightness uniformity is consistent.

[0040] Furthermore, the coupled beam-splitting array includes multiple beam-splitting films arranged at equal intervals, and is set at an angle γ to the plane of the light guide plate 10. Preferably, the angle γ = The light guide plate 10 uniformly distributes S-polarized light, which is reflected out of the waveguide and projected into the human eye to form the final display image. Since the coupled beam splitter only needs to process the S-polarized light that has been polarized and uniformly expanded, the reflectivity and wavelength response characteristics of the film can be optimized in a targeted manner to ensure that S-light of different regions and wavelengths can be coupled out with consistent efficiency, which greatly reduces the difficulty of the process and ultimately achieves a dual improvement in brightness and color uniformity, thereby improving the product yield.

[0041] The distance between the polarizing beam splitter and the coupling prism 11 is not less than the length of the pupil-expanding beam splitter 14, preferably not less than L, to ensure that the light forms a stable and predictable transmission state before reaching the polarizing beam splitter. This provides a precise incident angle distribution basis for the polarizing beam splitter to filter the light. This is because when the light undergoes total internal reflection on the upper and lower surfaces of the light guide plate 10, the phase changes of the S-light and P-light are different. The reason why pure S-light is not initially filtered at the optomechanical stage or at the coupling prism 11 stage is that after multiple total internal reflections in the light guide plate 10, the direction of its electric field vibration will be deflected, gradually mixing in the P-polarized component, and eventually forming a mixed polarization state, which cannot achieve the output of pure S-polarized light. Therefore, this scheme selects pure S-light within the light guide plate 10 and at a distance of not less than L between the polarizing beam splitter and the coupling prism 11. At this time, the polarization state of the light has not yet changed, and it can always maintain a single S-polarization characteristic, ensuring that the 50% splitting ratio of the pupil-expanding beam splitter 14 is accurately controllable and outputs a display image with uniform brightness.

[0042] This embodiment also provides an optical waveguide structure, which differs from the above in that the polarization beam splitter includes 2N transparent S-reflective P-films, where N≥2. Preferably, the multiple transparent S-reflective P-films are connected end-to-end to ensure that light transmitted at any angle can be filtered by the corresponding film, further improving the overall brightness uniformity; or adjacent transparent S-reflective P-films are connected end-to-end and are mirror-symmetrical to form multiple transparent S-reflective P-film groups. This means that the 2N transparent S-reflective P-films are divided into N groups according to a mirror-symmetrical relationship, with 2 mirror films in each group, that is, N S-reflective P-film groups are equally spaced. The specific number is set based on a comprehensive consideration of the actual transmission length of the light guide plate 10. Without specific limitations, N S-reflection P-film groups are evenly spaced, ensuring that light transmitted from any angle can be filtered by the corresponding film without gaps, and that the brightness of the edge and center fields of view can also achieve a high degree of consistency; or N transparent S-reflection P-film groups and N pupil-expanding beam-splitters 14 are alternately arranged at equal intervals, and the distance between the coupling prism 11 and the polarizing beam-splitter is kept not less than the length of one pupil-expanding beam-splitter 14, to ensure that the effective filtering area of ​​each combination is the same size, the number of filtered light rays per unit area is uniform, and the energy distribution of the single S-light entering the pupil-expanding beam-splitter 14 is uniform, ensuring higher brightness uniformity of the final coupled image.

[0043] This embodiment also provides an optical waveguide structure, which differs from the above in that it also includes a transition structure, namely a two-dimensional array optical waveguide structure. The transition structure includes multiple transition beam-splitting films that are equally spaced and inclined along a first direction. The coupling array beam-splitting film 15 includes multiple coupling beam-splitting films that are equally spaced and inclined along a second direction. The coupling beam-splitting films are parallel to the first direction or have a certain angle with it. The first direction is perpendicular to the second direction. The number of transition beam-splitting films and coupling beam-splitting films is set according to actual needs. The transition structure and the coupling array beam-splitting film 15 work together to achieve pupil expansion in both horizontal and vertical directions. Since the light needs to undergo more total internal reflections in the two-dimensional array optical waveguide, and the diversity of reflection angles is stronger, this leads to a faster evolution speed of polarization state and a more significant degree of polarization mixing, making it less suitable for use in optomechanics or in coupling prisms 11. The initial screening of the incident light is pure S-beam, which cannot meet the requirement of the pupil-expanding beam splitter 14 for a single S-beam. Therefore, this solution sets a polarization beam splitter and a pupil-expanding beam splitter 14 between the coupling prism 11 and the turning structure to screen the output S-polarized light. The filtered light then enters the output beam splitter 15 through the turning structure, which can output a display image with uniform brightness. For more details, please refer to the above description. In this solution, the polarization beam splitter, pupil-expanding beam splitter 14, turning beam splitter, and output beam splitter are designed only for the screened pure S-beam, which greatly simplifies the process complexity and ultimately achieves a dual improvement in brightness and color uniformity. Setting a transmissive S-reflective P-film with N≥2 can more effectively suppress the polarization mixing phenomenon in two-dimensional transmission, ensuring that the light from different directions is pure S-beam, and guaranteeing the integrity and brightness uniformity of the image after two-dimensional pupil expansion.

[0044] The above provides a detailed description of an optical waveguide structure 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 description of the above embodiments is only for the purpose of helping to understand the method 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. An optical waveguide structure, characterized in that, include: A light guide plate, comprising at least a coupling prism, a polarizing beam splitter, a pupil-expanding beam splitter, and an output beam splitter array arranged sequentially along the optical path transmission direction, wherein... The coupling prism is disposed in the coupling area of ​​the light guide plate to couple incident light into the light guide plate; the polarizing beam splitter includes at least 2N transparent S-reflective P-films embedded in the light guide plate at an angle, where N≥1, and two adjacent transparent S-reflective P-films are mirror-symmetrical; the pupil-expanding beam splitter is embedded in the middle of the thickness of the light guide plate and is parallel to the plane of the light guide plate, the polarizing beam splitter is disposed adjacent to the pupil-expanding beam splitter, and the pupil-expanding beam splitter is disposed adjacent to the coupling array beam splitter.

2. The optical waveguide structure according to claim 1, characterized in that, The output image field of view is set to Fov, the horizontal to vertical ratio is p:q, and the refractive index of the light guide plate is n. Then, the horizontal half-field of view Fov of the light guide plate in air is... h Satisfy: Fov h = When light propagates inside the light guide plate, the total internal reflection angle α satisfies: .

3. The optical waveguide structure according to claim 2, characterized in that, The coupling prism is a triangular prism, and the incident angle formed by the incident surface and the reflecting surface of the triangular prism is... θ =65°-75°.

4. The optical waveguide structure according to claim 3, characterized in that, Two adjacent transparent S-reflective P-films and one plane of the light guide plate form an isosceles triangle, and the base angle β of the isosceles triangle satisfies: β = θ -45° is used to filter out S-polarized light for total internal reflection transmission within the light guide plate.

5. The optical waveguide structure according to claim 4, characterized in that, The pupil-expanding beam-splitting film is a semi-transparent, semi-reflective film, embedded at half the thickness of the light guide plate. The length L of the pupil-expanding beam-splitting film is... .

6. The optical waveguide structure according to claim 5, characterized in that, The distance between the polarizing beam splitter and the coupling prism is not less than L.

7. The optical waveguide structure according to claim 6, characterized in that, The coupled array beam-splitting film includes multiple beam-splitting films embedded in the light guide plate. These multiple beam-splitting films are arranged at equal intervals and are tilted at an angle γ to the plane of the light guide plate. The tilt angle γ = .

8. The optical waveguide structure according to any one of claims 1-7, characterized in that, The polarization beam splitter includes two transmissive S-reflective P-films, which are connected end to end and are mirror-symmetrical.

9. The optical waveguide structure according to any one of claims 1-7, characterized in that, The polarization beam splitter includes 2N transparent S-reflective P-films, where N≥2. The multiple transparent S-reflective P-films are connected end to end, and two adjacent transparent S-reflective P-films are mirror-symmetrical, or adjacent transparent S-reflective P-films are connected end to end and are mirror-symmetrical to form multiple transparent S-reflective P-film groups. The multiple transparent S-reflective P-film groups are arranged at equal intervals.

10. A near-eye display device, characterized in that, Includes the optical waveguide structure according to any one of claims 1-9.

Images