Augmented reality display system based on free-form surface lens

Abstract

The invention discloses an augmented reality display system based on a free-form surface lens, and belongs to the field of augmented reality. According to the system, three mirrors of a traditional optical system are reduced to two mirrors, the system structure can be simplified, meanwhile, the coefficient order of the aspheric surface is increased, the large exit pupil size and the large eye distance can be achieved, the distortion value is reduced, the image quality is improved, additional optical assemblies are not needed, and light weight and batch production of augmented reality display system equipment are facilitated.

Description

Technical Field

[0001] The present invention relates to the field of augmented reality technology, and in particular to an augmented reality display system based on a free-form surface lens. Background Art

[0002] As the demand for display effects increases, augmented reality technology has received more and more attention. However, existing AR devices still face some challenges in optical design, such as small exit pupil size and large distortion value, which limit the application scope and user experience of AR devices. Therefore, it is of great practical significance to develop an AR display system with a large exit pupil size, low distortion value and simple structure. Summary of the invention

[0003] The present invention provides an augmented reality display system based on a free-form surface lens. By optimizing the design of the free-form surface lens, a larger exit pupil size is achieved, distortion value is reduced, image quality is improved, and no additional optical components are required, thereby making it possible to lightweight and mass-produce augmented reality (AR) devices.

[0004] The embodiment of the present invention provides an augmented reality display system based on a free-form surface lens, comprising: a main lens, an additional lens and a micro-optical machine;

[0005] The main lens is composed of two reflective lenses with different curvature radii but overlapping curvature centers;

[0006] The main lens and the additional lens are both designed with free-form surfaces, connected by a mechanical housing, and have an air gap. After passing through the micro-optical machine, the light is vertically incident on the main lens.

[0007] Optionally, in one embodiment of the present invention, the main lens includes a high refractive index free-form surface lens, a total reflection curved surface mirror and a partial reflection curved surface mirror, the high refractive index free-form surface lens is arranged between the total reflection curved surface mirror and the partial reflection curved surface mirror, the curved surface design of the additional lens is the same as that of the partial reflection curved surface mirror, and the additional lens is kept parallel and fixed to the partial reflection curved surface mirror through a mechanical housing, and there is an air gap between the two.

[0008] Optionally, in one embodiment of the present invention, the total reflection curved mirror and the partial reflection curved mirror are designed with an even aspheric surface, and the aspheric surface equation is:

[0009]

[0010] Where z(r) is the surface height at the mirror distance r from the optical axis, c is the surface curvature, k is the aspheric coefficient, and A i is the coefficient of the higher-order term, and n is the highest order.

[0011] Optionally, in one embodiment of the present invention, the centers of curvature of the total reflection curved mirror and the partial reflection curved mirror coincide, and the curvature of the total reflection curved mirror is a multiple of the curvature of the partial reflection curved mirror.

[0012] Optionally, in one embodiment of the present invention, the total reflection curved mirror and the partial reflection curved mirror have the following geometric constraint relationship:

[0013] X A1 ≥20;

[0014] X A1 =X A2 ;

[0015] Y A1 =-Y A2 ;

[0016] 10≤X A4 -X A1 ≤15;

[0017] 10≤X B4 -X B1 ≤15;

[0018] Y A2 =Y B1 ;

[0019] X A2 =X B1 ;

[0020] Y B4 -Y A3 ≥0;

[0021] Y B3 -Y A4 ≤0

[0022] Among them, A1~A4 are the visual field limit points of the upper end of the human eye on the high refractive index free-form surface lens numbered counterclockwise, A1 is the visual field limit point of the upper end of the high refractive index free-form surface lens closest to the human eye, B1~B4 are the visual field limit points of the lower end of the human eye on the high refractive index free-form surface lens numbered counterclockwise, B1 is the visual field limit point of the upper end of the high refractive index free-form surface lens closest to the human eye, with the human eye as the origin of the plane coordinate system, X Aj Y is the horizontal coordinate of the upper visual field limit point Ai, Aj is the vertical coordinate of the upper visual field limit point Ai, X Bj Y is the horizontal coordinate of the visual field limit point Bi at the bottom of the human eye, Bj It is the vertical coordinate of the visual field limit point Bi at the bottom of the human eye, j=1,2,3,4.

[0023] Optionally, in one embodiment of the present invention, there is a mirror coating on the surface of the partially reflecting curved mirror, so that the field of view of the real space observed through the partially reflecting curved mirror is limited, and visible light in the wavelength range of 0.48μm to 0.65μm is allowed to enter the human eye through the partially reflecting curved mirror.

[0024] Optionally, in one embodiment of the present invention, the display surface length of the micro-optical machine is the same as the length between the A3 field of view limit point and the B3 field of view limit point and maintains a distance from the high refractive index free-form surface lens, and the light passes through the micro-optical machine and then vertically enters the high refractive index free-form surface lens.

[0025] The augmented reality display system based on the free-form surface lens of the embodiment of the present invention optimizes the shape of the free-form surface lens so that the system has a larger exit pupil size. This reduces the need for personal adjustment, reduces the distortion value, and improves the image quality. At the same time, since the main lens only uses two components of the free-form surface optical element, no additional optical components are required, thereby simplifying the system structure.

[0026] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0028] Figure 1 A schematic diagram of an augmented reality display system based on a free-form surface lens provided according to an embodiment of the present invention;

[0029] Figure 2 FIG. 4 is a schematic diagram of a light path according to an embodiment of the present invention.

[0030] Figure numerals: 101 - high refractive index free-form surface lens; 102 - total reflection curved surface mirror; 103 - partial reflection curved surface mirror; 104 - additional lens; 105 - micro optical machine. DETAILED DESCRIPTION

[0031] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0032] Figure 1 The diagram is a schematic diagram of an augmented reality display system based on a free-form surface lens provided according to an embodiment of the present invention.

[0033] like Figure 1 As shown, the augmented reality display system based on the free-form surface lens includes: a main lens, an additional lens 104 and a micro-optical machine 105.

[0034] The main lens is composed of two reflective lenses with different curvature radii but overlapping centers of curvature;

[0035] The main lens uses high refractive index glass. The main lens and the additional lens 104 are both designed with free-form surfaces, connected by a mechanical housing, and maintaining a certain air gap. The maximum thickness of the lens is set to 15mm, and the eye distance is about 20mm. The light passes through the micro-optical machine 105 and then vertically enters the main lens.

[0036] The main lens plays the main role of optical refraction and reflection through two reflective lenses with different curvature radii but overlapping curvature centers. Its design optimizes the light path, effectively reduces optical distortion, and improves image quality. At the same time, the main lens adopts a free-form surface design, which increases the exit pupil size and eye distance, improves the user's visual experience, and can especially reduce eye fatigue when worn for a long time.

[0037] The additional lens is designed to cooperate with the main lens through an optimized curved surface to further enhance the optical performance of the system. It is parallel to the main lens, fixed in the mechanical housing, and separated from the main lens by an air gap. The design of the additional lens ensures good optical alignment and further reduces distortion, providing clear and precise image display, especially when the field of view is large, enhancing the effect of the overall optical system.

[0038] The micro-optical engine is responsible for converting image signals into light signals and accurately guiding the light into the main lens. The display surface length of the optical engine matches the distance to the limit point of the human eye's field of vision, ensuring the distortion-free display of the image. The micro-optical engine maintains a certain distance from the main lens to ensure that the light can accurately and vertically enter the main lens, thereby ensuring the clarity of the image and the accuracy of focus.

[0039] In an embodiment of the present invention, the main lens includes a high refractive index free-form surface lens 101, a total reflection curved surface mirror 102 and a partial reflection curved surface mirror 103. The high refractive index free-form surface lens 101 is arranged between the total reflection curved surface mirror 102 and the partial reflection curved surface mirror 103. The curved surface design of the additional lens 104 is the same as that of the partial reflection curved surface mirror 103. The additional lens 104 is kept parallel and fixed to the partial reflection curved surface mirror 103 through a mechanical housing, and there is an air gap between the two.

[0040] In the embodiment of the present invention, the total reflection curved mirror 102 and the partial reflection curved mirror 103 are designed with even aspheric surfaces, and the aspheric surface equation is:

[0041]

[0042] Where z(r) is the surface height at the mirror distance r from the optical axis, c is the surface curvature, k is the aspheric coefficient, and A i is the coefficient of the higher-order term, n is the highest order, A i Improving the image quality and lens characteristics will result in better results, but it will also increase the difficulty of processing.

[0043] In a specific embodiment, k is 0.2, the lens radius is selected to provide the required effective focal length of 30 mm, corresponding to a 0.49-inch diagonal display and a 24° field of view, i is 8th order, and the free-form surface coefficient of the total reflection curved mirror 102 is 1.825×10 –12 The free surface coefficient of the partially reflective curved mirror 103 is 1.591×10 –13 .

[0044] In the embodiment of the present invention, the curvature centers of the total reflection curved mirror 102 and the partial reflection curved mirror 103 coincide with each other, and the curvature of the total reflection curved mirror 102 is a multiple of the curvature of the partial reflection curved mirror 103 .

[0045] In the embodiment of the present invention, the total reflection curved mirror 102 and the partial reflection curved mirror 103 have a geometric constraint relationship. Figure 2 The human eye is shown as the origin of the plane coordinate system, A1 to A4 are the visual field limits of the upper end of the human eye, and B1 to B4 are the visual field limits of the lower end of the human eye. The geometric relationship constraints are as follows:

[0046] X A1 ≥20;

[0047] X A1 =X A2 ;

[0048] Y A1 =-Y A2 ;

[0049] 10≤X A4 -X A1 ≤15;

[0050] 10≤X B4 -X B1 ≤15;

[0051] Y A2 =Y B1 ;

[0052] X A2 =X B1 ;

[0053] Y B4 -Y A3 ≥0;

[0054] Y B3 -Y A4 ≤0

[0055] Among them, A1~A4 are the visual field limit points of the upper end of the human eye on the high refractive index free-form surface lens numbered counterclockwise, A1 is the visual field limit point of the upper end of the high refractive index free-form surface lens closest to the human eye, B1~B4 are the visual field limit points of the lower end of the human eye on the high refractive index free-form surface lens numbered counterclockwise, B1 is the visual field limit point of the upper end of the high refractive index free-form surface lens closest to the human eye, with the human eye as the origin of the plane coordinate system, X Aj Y is the horizontal coordinate of the upper visual field limit point Ai, Aj is the vertical coordinate of the upper visual field limit point Ai, X Bj Y is the horizontal coordinate of the visual field limit point Bi at the bottom of the human eye, Bj It is the vertical coordinate of the visual field limit point Bi at the bottom of the human eye, j=1,2,3,4.

[0056] In an embodiment of the present invention, there is a mirror coating on the partially reflecting curved mirror surface 103, so that the field of view of the real space observed through the partially reflecting curved mirror 103 is limited, and visible light in the wavelength range of 0.48μm to 0.65μm is allowed to enter the human eye through the partially reflecting curved mirror 103.

[0057] The partially reflective curved mirror coating only allows wavelengths of 0.48μm to 0.65μm to enter the user's eyes through the mirror coating, reducing external light sources or unnecessary reflections, ensuring that the user focuses on the content displayed in augmented reality (AR) rather than interference from the outside world. However, it also allows the user to see some details in the real environment, allowing the user to receive information from both the virtual world (display system) and the real world at the same time.

[0058] In one embodiment of the present invention, the display surface length of the micro-optical engine 103 is the same as the length between the A3 field of view limit point and the B3 field of view limit point and is kept at a distance from the high refractive index free-form surface lens 101. After passing through the micro-optical engine 105, the light is vertically incident on the high refractive index free-form surface lens 101.

[0059] Specifically, the display surface length of the micro-optical engine 105 is the same as the length between A3 and B3 and the distance from the inclined surface of the high refractive index free-form surface lens 101 is 7 mm.

[0060] According to the augmented reality display system based on free-form surface lenses proposed in an embodiment of the present invention, the three mirrors of the traditional optical system are reduced to two, and the coefficient order of the aspheric surface is increased. It can achieve a larger exit pupil size and a large eye distance, reduce distortion values, improve image quality without the need for additional optical components, and contribute to the lightweight and mass production of augmented reality display system (AR) devices.

[0061] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0062] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

Claims

1. An augmented reality display system based on a free-form surface lens, characterized in that: include: Main lens, additional lens and micro-optical machine; The main lens is composed of two reflective lenses with different curvature radii but overlapping curvature centers; The main lens and the additional lens are both designed with free-form surfaces, connected by a mechanical housing, and have an air gap. After passing through the micro-optical machine, the light is vertically incident on the main lens.

2. The augmented reality display system based on free-form surface lens according to claim 1, characterized in that: The main lens includes a high-refractive index free-form surface lens, a total reflection curved surface mirror and a partial reflection curved surface mirror. The high-refractive index free-form surface lens is arranged between the total reflection curved surface mirror and the partial reflection curved surface mirror. The curved surface design of the additional lens is the same as that of the partial reflection curved surface mirror. The additional lens is kept parallel and fixed to the partial reflection curved surface mirror through a mechanical housing, and there is an air gap between the two.

3. The augmented reality display system based on free-form surface lens according to claim 2, characterized in that: The total reflection curved mirror and the partial reflection curved mirror are designed with even aspheric surfaces, and the aspheric surface equation is: Where z(r) is the surface height at the mirror distance r from the optical axis, c is the surface curvature, k is the aspheric coefficient, and A i is the coefficient of the higher-order term, and n is the highest order.

4. The augmented reality display system based on free-form surface lens according to claim 2, characterized in that: The curvature centers of the total reflection curved mirror and the partial reflection curved mirror coincide with each other, and the curvature of the total reflection curved mirror is a multiple of the curvature of the partial reflection curved mirror.

5. The augmented reality display system based on free-form surface lens according to claim 2, characterized in that: The total reflection curved mirror and the partial reflection curved mirror have the following geometric constraint relationship: X A1 ≥20； X A1 =X A2 ; AND A1 -And A2 ; 10≤X A4 -X A1 ≤15; 10≤X B4 -X B1 ≤15; AND A2 =And B1 ; X A2 =X B1 ; AND B4 -AND A3 ≥0; AND B3 -AND A4 ≤0 Among them, A1~A4 are the visual field limit points of the upper end of the human eye on the high refractive index free-form surface lens numbered counterclockwise, A1 is the visual field limit point of the upper end of the high refractive index free-form surface lens closest to the human eye, B1~B4 are the visual field limit points of the lower end of the human eye on the high refractive index free-form surface lens numbered counterclockwise, B1 is the visual field limit point of the upper end of the high refractive index free-form surface lens closest to the human eye, with the human eye as the origin of the plane coordinate system, X Aj Y is the horizontal coordinate of the upper visual field limit point Ai, Aj is the vertical coordinate of the upper visual field limit point Ai, X Bj Y is the horizontal coordinate of the visual field limit point Bi at the bottom of the human eye, Bj It is the vertical coordinate of the visual field limit point Bi at the bottom of the human eye, j=1,2,3,4.

6. The augmented reality display system based on free-form surface lens according to claim 2, characterized in that: There is a mirror coating on the surface of the partially reflecting curved mirror, so that the field of view of the real space observed through the partially reflecting curved mirror is limited, and visible light in the wavelength range of 0.48μm to 0.65μm is allowed to enter the human eye through the partially reflecting curved mirror.

7. The augmented reality display system based on free-form surface lens according to claim 5, characterized in that: The display surface length of the micro-optical machine is the same as the length between the A3 field of view limit point and the B3 field of view limit point and keeps a distance from the high refractive index free-form surface lens. After passing through the micro-optical machine, the light is vertically incident on the high refractive index free-form surface lens.

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