A thin catadioptric near-eye display optical system
Patent Information
- Application Number
- CN202611296247.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-25
- Publication Date
- 2026-10-30
AI Technical Summary
微显示器距离人脸过近，其持续高频运转产生的热量直接向人脸表面区域辐射；并且，受限于微显示器必须贴近人脸侧的布局方式，现有的光路架构无法在维持系统光学参数的前提下，进一步折叠并压缩整个光学系统在厚度方向上的机械尺寸，导致近眼显示设备在工作状态下厚度偏大且人脸侧区域热负荷过高
1、本发明通过在微显示器与出瞳之间设置透镜组、第一棱镜、第二棱镜以及反射镜，构建棱镜折反混合的折叠光路结构。该结构将微显示器物理布置于远离系统出瞳的一侧，直接增大发热源与人脸之间的空间距离，有效降低近眼显示模组工作时产生的热量对人脸的散热影响。同时，光路在第一棱镜与第二棱镜的特定界面之间经历全内反射、反射与透射循环，大幅缩短光学系统的机械长度。这种空间布局实现了系统在YOZ平面内光学厚度小于13毫米的超薄化设计，显著减轻近眼显示设备的配戴负荷并提升人脸侧的空间舒适度与使用体验。
Smart Images
Figure CN123010258A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of near-eye display technology, specifically to a thin near-eye display optical system with prism reflection and deflection hybrid technology. Background Technology
[0002] A near-eye display optical system is a visual device that magnifies and projects an image from a microdisplay onto the pupil of the human eye using optical elements. As a core photoelectric conversion and transmission module in virtual reality and augmented reality hardware, the near-eye display optical system mainly consists of optical transmission elements such as microdisplays, relay lens groups, prisms, or waveguides. The system's basic function is to construct a display optical path for a virtual image within a limited physical space close to the human eye, enabling the human eye to observe and perceive the image on a tiny, luminous screen through optical magnification and aberration correction.
[0003] Existing near-eye display optical systems typically employ direct-transmission or conventional catadioptric optical path architectures for image light transmission. In existing system layouts, light emitted from the microdisplay passes through the front lens group and directly enters the eyepiece or monolithic reflecting prism, then deflects and exits to the system's exit pupil. To achieve short focal length and wide field of view coverage, current hardware designs typically arrange the microdisplay and its associated optical components closely along the optical path axis, ensuring that the microdisplay is directly facing or laterally close to the reference plane where the system's exit pupil is located, thus guaranteeing that light reaches the eye via a shorter, straight physical path.
[0004] Existing near-eye display optical systems suffer from spatial layout defects due to the placement of heat sources. During operation, the heat generated by the near-eye display optical module is primarily concentrated at the microdisplay. In conventional optical path designs, constrained by the straight-line transmission or single-reflection path of light, the microdisplay is physically positioned extremely close to the face. This proximity causes the heat generated by the microdisplay's continuous high-frequency operation to radiate directly onto the face's surface. Furthermore, due to the microdisplay's close proximity to the face, existing optical architectures cannot further fold and compress the mechanical dimensions of the entire optical system in the thickness direction while maintaining system optical parameters. This results in near-eye display devices being excessively thick during operation and experiencing excessive heat load on the face side. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a thin near-eye display optical system with prism reflection and deflection hybrid technology, which solves the problems mentioned in the background section.
[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: a thin near-eye display optical system with prism reflection and deflection, comprising a microdisplay 16, a lens / lens group 15, a first prism 12, a second prism 13, and a reflector 14.
[0007] The microdisplay 16 has a light-emitting surface 110 and an exiting surface 109. The microdisplay 16 is located on the side away from the system exit pupil 101. The lens / lens group 15 has a seventh surface 108 and a sixth surface 107. The seventh surface 108 is disposed facing the exiting surface 109 of the microdisplay 16. The lens / lens group 15 is disposed between the microdisplay 16 and the first prism 12. The first prism 12 has a fifth surface 106, a first surface 102, and a second surface 103. The second prism 13 has a second surface 103 and a third surface 104. The second surface 103 is the interface between the first prism 12 and the second prism 13. The first prism 12 and the second prism 13 are arranged adjacent to each other. The reflector 14 has a fourth surface 105. The reflector 14 is located on the side of the second prism 13 away from the first prism 12.
[0008] The light transmission path in the thin near-eye display optical system of the prism refraction-reflection hybrid system is as follows: Light emitted from the light-emitting surface 110 of the microdisplay 16 exits from the exit surface 109; Light passes sequentially through the seventh surface 108 and the sixth surface 107 of the lens / lens group 15; Light is refracted into the first prism 12 via the fifth surface 106; Light propagates inside the first prism 12, and upon first reaching the first surface 102, total internal reflection occurs, satisfying the condition; After total internal reflection, the light reaches the second surface 103 for the first time and is reflected; After reflection, the light reaches the first surface 102 for the second time, at which point the angle of incidence does not satisfy the condition for total internal reflection, and the light is reflected again; After reflection, the light reaches the second surface 103 for the second time, and is transmitted through the second surface 103 into the second prism 13; Light entering the second prism 13 is transmitted through the third surface 104 and reaches the fourth surface 105 of the reflector 14. The light is reflected by the fourth surface 105, and then passes through the third surface 104, the second surface 103 and the first surface 102 in sequence, before leaving the first prism 12 and reaching the system exit pupil 101.
[0009] The optical folding transmission medium formed by the combination of the first prism 12 and the second prism 13 controls the light to complete total internal reflection, reflection, and transmission between the first surface 102 and the second surface 103 in a specific sequence. This folded optical path structure adjusts the physical position of the microdisplay 16, which serves as the main heat source, to the side away from the exit pupil 101, increasing the spatial distance between the heat source and the face side. At the same time, the folded optical path compresses the system space, making the optical thickness of the thin near-eye display optical system with prism reflection and deflection hybrid technology less than 13 mm in the YOZ plane.
[0010] To improve optical imaging quality, the sixth surface 107 of the lens / lens group 15, the fifth surface 106 of the first prism 12, and the fourth surface 105 of the mirror 14 are configured as aspherical surfaces. The aspherical surface shape is specifically defined by an equation containing the sag of a point on the surface, the reciprocal of the radius of curvature, the radial distance of a point on the surface, the quadratic constant, and higher-order coefficients. Both the sixth surface 107 of the lens / lens group 15 and the fifth surface 106 of the first prism 12 have eccentric and curved features. The fourth surface 105 of the mirror 14 is configured as a freeform surface to further correct aberrations.
[0011] In terms of the optical interface film system configuration, the first surface 102 and the second surface 103 of the first prism 12 are coated with a beam-splitting film; the fourth surface 105 of the reflector 14 is coated with a reflective film, which is used to improve light efficiency; and the remaining light-transmitting surfaces in the thin near-eye display optical system of the prism refraction-reflection hybrid system are coated with an anti-reflection film.
[0012] In terms of optical materials, the first prism 12 and the second prism 13 are formed from optical resin or optical glass with a high refractive index. Optical resin is used to reduce the weight of the system, while optical glass with a high refractive index is used to achieve a large field of view and short focal length system. The lens / lens group 15 is an optical resin aspherical lens or an optical glass aspherical lens.
[0013] The above-described architecture's parameter configurations allow the diagonal size of the microdisplay 16 to be compatible with a range of 0.40 inches to 0.80 inches. The virtual image display optical path of the prism-reflection hybrid thin near-eye display optical system has a field of view greater than 40°, optical distortion less than 2.5%, and a system focal length satisfying f ≤ 21 mm.
[0014] This invention provides a thin near-eye display optical system with prism reflection and deflection hybrid technology. It has the following advantages: 1. This invention constructs a folded optical path structure with hybrid prism reflection and deflection by placing a lens group, a first prism, a second prism, and a reflector between the microdisplay and the exit pupil. This structure physically positions the microdisplay away from the system's exit pupil, directly increasing the spatial distance between the heat source and the face, effectively reducing the impact of heat generated by the near-eye display module on the face's heat dissipation. Simultaneously, the optical path undergoes a cycle of total internal reflection, reflection, and transmission at a specific interface between the first and second prisms, significantly shortening the mechanical length of the optical system. This spatial layout achieves an ultra-thin design with an optical thickness of less than 13 mm in the YOZ plane, significantly reducing the wearing load of near-eye display devices and improving spatial comfort and user experience on the face side.
[0015] 2. This invention establishes a precise wavefront aberration correction mechanism by configuring aspherical or freeform surfaces on the lens group surface, the light-incident surface of the first prism, and the reflector surface, and by precisely defining the aspherical surface sag, reciprocal of the radius of curvature, radial distance, quadratic surface constant, and higher-order term coefficients. The eccentricity and curvature characteristics of the lens group surface, combined with the multiple folding paths inside the prism, work synergistically to deeply compensate for off-axis aberrations generated at large field of view angles. This aspherical and freeform surface design directly eliminates image plane curvature and distortion in optical transmission, enabling the field of view of the near-eye display optical system to be greater than 40 degrees, while controlling optical distortion to within 2.5%, ensuring the geometrical proportion reproduction and image sharpness of the virtual image under near-eye observation conditions.
[0016] 3. This invention achieves precise control over the optical transmission light flux by depositing a beam-splitting film at the prism interface, a high-efficiency reflective film on the reflector surface, and an anti-reflection film on the remaining transparent surfaces. The beam-splitting film precisely controls the total internal reflection and transmittance of light between the first and second prism interfaces, minimizing stray light interference and improving the signal-to-noise ratio. The high-efficiency reflective film enhances the light energy feedback efficiency of the terminal reflector surface. Combined with the optimized selection of optical resin or high-refractive-index glass materials, high transmittance is achieved while reducing the overall system weight. This optimized combination of materials and film system effectively widens the system's focal length adjustment range to below 21 mm, significantly optimizes the energy transmission path, and improves the optical imaging light energy utilization and image contrast of the near-eye display system. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the overall optical path of the present invention; Figure 2 This is a schematic diagram of the optical surface of the present invention; Figure 3 This is a schematic diagram of the central optical path of the present invention; Figure 4 This is the MTF curve of the present invention; Figure 5 This is the distorted mesh diagram of the present invention.
[0018] Among them, 11, exit pupil; 12, first prism; 13, second prism; 14, reflecting mirror; 15, lens / lens group; 16, microdisplay; 101, system exit pupil; 102, first surface; 103, second surface; 104, third surface; 105, fourth surface; 106, fifth surface; 107, sixth surface; 108, seventh surface; 109, exiting surface; 110, emitting surface. Detailed Implementation
[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] Please see the appendix Figure 1 -Appendix Figure 5 This invention provides a thin near-eye display optical system with prism reflection and deflection hybrid, including a microdisplay 16, a lens / lens group 15, a first prism 12, a second prism 13, and a reflector 14.
[0021] The microdisplay 16 is located on the side away from the exit pupil 101. The lens / lens group 15 is located between the microdisplay 16 and the first prism 12. The first prism 12 and the second prism 13 are arranged adjacent to each other. The reflector 14 is located on the side of the second prism 13 away from the first prism 12.
[0022] The light transmission path in the hybrid near-eye display optical system is as follows: The light emitted from the light-emitting surface 110 of the microdisplay 16 is emitted from the exiting surface 109; Light rays are transmitted sequentially through the seventh surface 108 and the sixth surface 107 of the lens / lens group 15; Light enters the first prism 12 through the refraction of the fifth surface 106; When light travels inside the first prism 12, it undergoes total internal reflection when it first reaches the first surface 102 of the first prism 12, satisfying the condition for total internal reflection. After total internal reflection, the light reaches the interface between the first prism 12 and the second prism 13 for the first time, namely the second surface 103, and is reflected by the second surface 103. The reflected light reaches the first surface 102 a second time. At this time, the angle of incidence does not meet the condition for total internal reflection, and the light is reflected by the first surface 102. The reflected light reaches the second surface 103 a second time, and the light is transmitted through the second surface 103 and enters the second prism 13; The light entering the second prism 13 is transmitted through the third surface 104 of the second prism 13 and reaches the fourth surface 105 of the reflector 14. Light is reflected by the fourth surface 105 and then passes through the third surface 104, the second surface 103 and the first surface 102 in sequence. The light detaches from the first prism 12 and reaches the system exit pupil 101.
[0023] The diagonal size of the microdisplay 16 ranges from 0.40 inches to 0.80 inches. The microdisplay 16 has a light-emitting surface 110 and an emitting surface 109. The light-emitting surface 110 and the emitting surface 109 are arranged sequentially along the light emission direction. The microdisplay 16 is located on the side away from the system exit pupil 101.
[0024] A lens / lens group 15 is disposed in the optical path between the microdisplay 16 and the first prism 12. The lens / lens group 15 has a seventh surface 108 and a sixth surface 107. The seventh surface 108 is disposed facing the exit surface 109 of the microdisplay 16, and the sixth surface 107 is disposed facing the fifth surface 106 of the first prism 12.
[0025] The lens / lens group 15 is an optical resin aspherical lens or an optical glass aspherical lens. The sixth surface 107 of the lens / lens group 15 and the fifth surface 106 of the first prism 12 are aspherical. Both the sixth surface 107 of the lens / lens group 15 and the fifth surface 106 of the first prism 12 have eccentric and curved features.
[0026] Light emitted from the light-emitting surface 110 of the microdisplay 16 exits from the exiting surface 109 and is transmitted sequentially through the seventh surface 108 and the sixth surface 107 of the lens / lens group 15. The lens / lens group 15 is used to expand the field of view and reduce distortion. The light transmitted through the sixth surface 107 is incident on the fifth surface 106 of the first prism 12.
[0027] The first prism 12 and the second prism 13 are formed from optical resin material or optical glass. Optical resin material is used to reduce system weight. High-refractive-index optical glass is used to achieve a large field-of-view, short-focal-length system. The first prism 12 has a fifth surface 106, a first surface 102, and a second surface 103. The second prism 13 has a second surface 103 and a third surface 104. The second surface 103 forms the interface between the first prism 12 and the second prism 13.
[0028] The first surface 102 and the second surface 103 are coated with a beam-splitting film. The remaining light-transmitting surfaces in the system are coated with an anti-reflection film.
[0029] Light rays emitted from lens / lens group 15 are refracted by the fifth surface 106 and enter the first prism 12.
[0030] The light travels inside the first prism 12 and reaches the first surface 102 for the first time. At this time, the angle of incidence of the light satisfies the condition of total internal reflection, and the light undergoes total internal reflection on the first surface 102.
[0031] After total internal reflection, the light reaches the second surface 103 for the first time and is reflected by the second surface 103.
[0032] The reflected light reaches the first surface 102 a second time. At this time, the angle of incidence of the light does not meet the condition of total internal reflection, and the light is reflected by the first surface 102.
[0033] The reflected light reaches the second surface 103 a second time, and the light is transmitted through the second surface 103 and enters the second prism 13.
[0034] The light entering the second prism 13 is transmitted through the third surface 104 and reaches the fourth surface 105 of the reflector 14.
[0035] After being reflected by the fourth surface 105, the light passes through the third surface 104, the second surface 103 of the second prism 13 and the first surface 102 of the first prism 12 in sequence, and reaches the exit pupil 101 of the system.
[0036] The optical path is folded in the first prism 12 and the second prism 13, and the optical thickness of the catadioptric hybrid near-eye display optical system in the YOZ plane is less than 13 mm.
[0037] The reflector 14 is located on the side of the second prism 13 away from the first prism 12. The reflector 14 has a fourth surface 105.
[0038] The fourth surface 105 is coated with a reflective film. The reflective film on the fourth surface 105 is used to improve light efficiency. Light transmitted from the third surface 104 of the second prism 13 reaches the fourth surface 105. The light is reflected by the fourth surface 105.
[0039] The fourth surface 105 of the reflector 14 is an aspherical or freeform surface. In the catadioptric hybrid near-eye display optical system, the sixth surface 107 of the lens / lens group 15, the fifth surface 106 of the first prism 12, and the fourth surface 105 of the reflector 14 are all aspherical.
[0040] The above aspherical surfaces satisfy the following equation:
[0041] In the formula, Let the elevation of a point on the surface be sag. radius of curvature The reciprocal, Let be the radial distance from a point on the surface. For quadratic surface constants, For higher-order terms, The values are 2, 3, 4, and 5. Example 1 The virtual image display optical path field of view of the catadioptric hybrid near-eye display optical system is greater than 40°. The optical distortion of the catadioptric hybrid near-eye display optical system is less than 2.5%. The focal length of the catadioptric hybrid near-eye display optical system satisfies f ≤ 21mm. The optical thickness of the catadioptric hybrid near-eye display optical system in the YOZ plane is less than 13mm.
[0042] The optical system parameters of the optical path in Example 1 are shown in the table below. The types and data of eccentricity in the table refer to the definitions in the CODE V software.
[0043] Table 1 Optical system parameters of the optical path
[0044] Table 2 Aspherical Coefficients
[0045] Please see Figure 4 and Figure 5 The MTF curve of the catadioptric hybrid near-eye display optical system is used to characterize the modulation transfer function of the system at different spatial frequencies, and the distortion grid diagram of the catadioptric hybrid near-eye display optical system is used to characterize the distortion deviation of the system's field of view. Based on the verification results of the above charts, the virtual image display optical path field of view of the catadioptric hybrid near-eye display optical system is greater than 40°, and the optical distortion is less than 2.5%. Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A thin near-eye display optical system with prism reflection and deflection hybrid, comprising a microdisplay (16), a lens / lens group (15), a first prism (12), a second prism (13), and a reflector (14), characterized in that, The microdisplay (16) has a light-emitting surface (110) and an emission surface (109), and the microdisplay (16) is located on the side away from the system exit pupil (101); The lens / lens group (15) has a seventh surface (108) and a sixth surface (107). The seventh surface (108) is disposed facing the exit surface (109) of the microdisplay (16). The lens / lens group (15) is disposed between the microdisplay (16) and the first prism (12). The first prism (12) has a fifth surface (106), a first surface (102) and a second surface (103), and the second prism (13) has a second surface (103) and a third surface (104). The second surface (103) is the interface between the first prism (12) and the second prism (13). The first prism (12) and the second prism (13) are arranged adjacent to each other. The reflector (14) has a fourth surface (105) and is located on the side of the second prism (13) away from the first prism (12).
2. The thin near-eye display optical system with prism reflection and deflection hybrid technology according to claim 1, characterized in that, The sixth surface (107) of the lens / lens group (15), the fifth surface (106) of the first prism (12) and the fourth surface (105) of the mirror (14) are all aspherical surfaces; the aspherical surfaces are defined by an equation that includes the sag of a point on the surface, the reciprocal of the radius of curvature, the radial distance of a point on the surface, the quadratic constant and the coefficients of higher-order terms.
3. The thin near-eye display optical system with prism reflection and deflection hybrid technology according to claim 2, characterized in that, The sixth surface (107) of the lens / lens group (15) and the fifth surface (106) of the first prism (12) both have eccentric and curved features.
4. The thin near-eye display optical system with prism reflection and deflection hybrid technology according to claim 1, characterized in that, The first surface (102) and the second surface (103) of the first prism (12) are coated with a beam-splitting film; the fourth surface (105) of the reflector (14) is coated with a reflective film, which is used to improve light efficiency; the remaining light-transmitting surfaces are coated with an anti-reflection film.
5. The thin near-eye display optical system with prism reflection and deflection hybrid technology according to claim 1, characterized in that, The first prism (12) and the second prism (13) are formed by processing optical resin material, and the optical resin material is used to reduce the weight of the system; or, the first prism (12) and the second prism (13) are formed by processing optical glass with high refractive index, and the optical glass with high refractive index is used to realize a large field of view short focal length system.
6. The thin near-eye display optical system with prism reflection and deflection hybrid technology according to claim 1, characterized in that, The lens / lens group (15) is an optical resin aspherical lens or an optical glass aspherical lens, and the diagonal size of the microdisplay (16) ranges from 0.40 inches to 0.80 inches.
7. The thin near-eye display optical system with prism reflection and deflection hybrid technology according to claim 1, characterized in that, The light transmission path is as follows: Light emitted from the light-emitting surface (110) of the microdisplay (16) is emitted from the emission surface (109); Light rays are transmitted sequentially through the seventh surface (108) and the sixth surface (107) of the lens / lens group (15). Light enters the first prism (12) through the fifth surface (106) of the first prism (12). When light travels inside the first prism (12) and reaches the first surface (102) for the first time, total internal reflection occurs, satisfying the condition for total internal reflection. The light rays after total internal reflection reach the second surface (103) for the first time and are reflected by the second surface (103); The reflected light reaches the first surface (102) a second time. At this time, the angle of incidence of the light does not meet the condition of total internal reflection, and the light is reflected by the first surface (102). The reflected light reaches the second surface (103) a second time, and the light passes through the second surface (103) and enters the second prism (13). Light entering the second prism (13) is transmitted through the third surface (104) and reaches the fourth surface (105) of the reflector (14). The light is reflected by the fourth surface (105), and then passes through the third surface (104), the second surface (103) and the first surface (102) in sequence, exits the first prism (12), and reaches the exit pupil (101) of the system.
8. The thin near-eye display optical system with prism reflection and deflection hybrid technology according to claim 1, characterized in that, The virtual image display has a field of view of more than 40° and an optical distortion of less than 2.5%.
9. The thin near-eye display optical system with prism reflection and deflection hybrid technology according to claim 1, characterized in that, The focal length of the thin near-eye display optical system with prism reflection and deflection is f≤21mm; the optical path is folded in the first prism (12) and the second prism (13), and the optical thickness in the YOZ plane is less than 13mm.
10. The thin near-eye display optical system with prism reflection and deflection hybrid technology according to claim 1, characterized in that, The fourth surface (105) of the mirror (14) is a freeform surface, which is used to improve the quality of optical imaging.