A visual optical system

Abstract

The present application discloses a visual optical system, comprising: a first element group, a second lens, a third lens, and a light source; wherein the first element group, the second lens, and the third lens are arranged in sequence along the optical axis from the human eye side to the light source position; wherein the second lens has positive optical power; wherein the first element group comprises a first lens, a reflective polarizing element, and a quarter-wave plate; wherein the first lens, the reflective polarizing element, the quarter-wave plate, the second lens, and the third lens have at least one far light surface away from the light source and one near light surface close to the light source; wherein at least one of the near light surface of the first lens and the near light surface of the second lens has a partial reflective layer; wherein the effective focal length f of the optical system, the effective focal length f2 of the second lens, and half of the maximum field of view Semi‑FOV of the visual optical system satisfy: 2 <f2 / (f×tan(Semi‑FOV))<6。

Description

Technical Field

[0001] The present invention relates to the field of optics, and in particular to a visual optical system. Background Art

[0002] Virtual Reality (VR), based on the development of computer integration, integrates 3D graphics, multimedia, simulation, display, and servo technologies to create a realistic 3D visual experience, and even sensory experiences like touch and smell, giving people in the virtual world an immersive feeling. As the output terminal for virtual images, the display device of the visual optical system is particularly important in practical use. Its compatibility with the human visual system at close range and the overall portability of the device are particularly important.

[0003] Current optical path folding schemes that incorporate polarization principles can effectively reduce the distance between the screen and the lens, helping to shorten the overall length of the optical system. However, due to limitations in screen size and the curvature of the film surface, the optical system's field of view is small and image quality is poor at the edges. Therefore, based on this principle, the present invention utilizes a three-lens polarization element scheme. While controlling the overall optical length, this approach rationally allocates lens types and focal lengths to achieve a wide field of view design for a limited screen size. It also optimizes edge field aberrations and enhances the visual experience.

[0004] The preceding description is intended to provide general background information and does not necessarily constitute prior art. Summary of the Invention

[0005] The present application aims to provide a visual optical system that adopts a three-piece optical path folding solution to reduce the thickness of the VR system, solve the problem of poor imaging in the edge field of view, reduce dizziness, and enhance the consumer experience.

[0006] The present application provides a visual optical system, which includes: a first element group, a second lens, a third lens, and a light source; wherein the first element group, the second lens, and the third lens are arranged in sequence along the optical axis from the human eye side to the light source position; wherein the second lens has positive optical power; wherein the first element group includes a first lens, a reflective polarizing element, and a quarter-wave plate; wherein the first lens, the reflective polarizing element, the quarter-wave plate, the second lens, and the third lens have a far light surface away from the light source and a near light surface close to the light source; wherein at least one of the near light surface of the first lens and the near light surface of the second lens has a partial reflective layer; wherein the effective focal length f of the optical system, the effective focal length f2 of the second lens, and half of the maximum field of view Semi-FOV of the visual optical system satisfy: 2 <f2 / (f×tan(Semi-FOV))<6。

[0007] The present application also provides a visual optical system, which includes: a first element group, a second lens, a third lens, and a light source; wherein the first element group, the second lens, and the third lens are arranged in sequence along the optical axis from the human eye side to the light source position; wherein the first element group and the second lens both have positive optical power; wherein the first element group includes a first lens, a reflective polarizing element and a quarter-wave plate; wherein the first lens, the reflective polarizing element, the quarter-wave plate, the second lens and the third lens have a far light surface away from the light source and a near light surface close to the light source; wherein at least one of the near light surface of the first lens and the near light surface of the second lens has a partial reflective layer; wherein the combined focal length FG12 of the first lens, the reflective polarizing element, the quarter-wave plate and the second lens, the center thickness CT1 of the first lens on the optical axis, and the air spacing T12 between the first lens and the second lens on the optical axis satisfy: 3.0 <FG12 / (CT1+T12)<12。

[0008] According to one embodiment of the present application, an on-axis distance SAG21 between the intersection of the second lens's far light surface and the optical axis and the vertex of the effective radius of the second lens's far light surface, and an on-axis distance SAG22 between the intersection of the second lens's near light surface and the optical axis and the vertex of the effective radius of the second lens' near light surface, satisfy:

[0009] -1<(SAG21+SAG22) / (SAG21-SAG22)<5.5.

[0010] According to one embodiment of the present application, the on-axis distance SAG31 between the intersection of the far light surface of the third lens and the optical axis and the vertex of the effective radius of the far light surface of the third lens, and the on-axis distance SAG32 between the intersection of the near light surface of the third lens and the optical axis and the vertex of the effective radius of the near light surface of the third lens, satisfy:

[0011] -2.5<(SAG31+SAG32) / (SAG31-SAG32)<9.0.

[0012] According to one embodiment of the present application, the Abbe number V1 of the first lens, the refractive index N1 of the first lens, the Abbe number V3 of the third lens, and the refractive index N3 of the third lens satisfy: 59 <V1 / N1+V3 / N3<95。

[0013] According to one embodiment of the present application, a curvature radius R5 of the far light surface of the third lens, a curvature radius R6 of the near light surface of the third lens, and a combined focal length f23 of the second lens and the third lens satisfy: 0.5<(R5+R6) / f23<4.0.

[0014] According to an embodiment of the present application, for the central thickness CT2 of the second lens on the optical axis and the combined focal length FG12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens, the following is satisfied: 2.0 < FG12 / CT2 < 6.2.

[0015] According to an embodiment of the present application, for the Abbe number Vi of the i-th lens and the maximum refractive index Nmax among the first lens, the reflective polarizing element, the quarter-wave plate, the second lens, and the third lens, the following is satisfied: 1 < Vi / 10 / Nmax < 5; where i = 1, 2, or 3.

[0016] According to an embodiment of the present application, for the on-axis distance TD from the far-light surface of the first lens to the far-light surface of the last lens and the combined focal length FG12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens, the following is satisfied: 1 < FG12 / TD < 2.3.

[0017] According to an embodiment of the present application, for the on-axis distance TD from the far-light surface of the first lens to the far-light surface of the last lens, the central thickness CT1 of the first lens on the optical axis, and the central thickness CT3 of the third lens on the optical axis, the following is satisfied: 7.0 < TD / CT1 + TD / CT3 < 28.0.

[0018] According to an embodiment of the present application, for the radius of curvature R3 of the far-light surface of the second lens and the radius of curvature R4 of the near-light surface of the second lens, the following is satisfied: |R3 / R4| < 6.0.

[0019] According to an embodiment of the present application, for the radius of curvature R4 of the far-light surface of the second lens and the effective focal length f2 of the second lens, the following is satisfied: |f2 / R4| < 3.0.

[0020] According to an embodiment of the present application, for the effective focal length f of the optical system and the central thickness CT2 of the second lens on the optical axis, the following is satisfied: 2.0 < f / CT2 < 5.5.

[0021] According to an embodiment of the present application, the near-light surface of the quarter-wave plate is at least partially in contact with the far-light surface of the first lens.

[0022] According to an embodiment of the present application, the far-light surface of the reflective polarizing element is at least partially in contact with the near-light surface of the first lens; the near-light surface of the reflective polarizing element is at least partially in contact with the far-light surface of the quarter-wave plate.

[0023] Advantages of the present application:

[0024] The visual optical system provided by the present application adopts a positive focal length design for the second lens, which facilitates light convergence, helps reduce the size of components, and further reduces the volume of the visual optical system equipment. The third lens is used to flexibly compensate for the distortion and dispersion produced by the optical element group in front, further optimize the aberration and improve the imaging quality. At the same time, by limiting the relationship between the focal length of the second lens and the system focal length and the half-field angle, it is convenient to distribute the focal length of the system, which is conducive to the design of small focal length and large field of view, and can constrain the system image height to a certain extent, which is convenient for the selection of light source size. By controlling the combined focal length of the first lens, reflective polarizing element, quarter-wave plate, and second lens, the thickness of the first lens, and the air gap between the first and second lenses, it is conducive to controlling the molding and assembly strength of the first lens, further controlling the total length of the optical design on the basis of avoiding interference between the first and second lenses, and at the same time, coordinating with the focal length control is conducive to maximizing the field of view angle and increasing the user's visual immersion experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0026] Figure 1 This is a schematic structural diagram of the optical imaging system of this application;

[0027] Figures 2a to 2c They are respectively the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illumination curve of Example 1 of the optical imaging system of the present application;

[0028] Figure 3 This is a schematic structural diagram of the optical imaging system of this application;

[0029] Figures 4a to 4c They are respectively the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illumination curve of Example 2 of the optical imaging system of the present application;

[0030] Figure 5 This is a schematic structural diagram of the optical imaging system of this application;

[0031] Figures 6a to 6c They are respectively the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illumination curve of Example 3 of the optical imaging system of the present application;

[0032] Figure 7 This is a schematic structural diagram of the optical imaging system of this application;

[0033] Figures 8a to 8cThey are respectively the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illumination curve of Example 4 of the optical imaging system of the present application;

[0034] Figure 9 This is a schematic structural diagram of the optical imaging system of this application;

[0035] Figures 10a to 10c They are respectively the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illumination curve of Example 5 of the optical imaging system of the present application;

[0036] Figure 11 This is a schematic structural diagram of the optical imaging system of this application;

[0037] Figures 12a to 12c They are respectively the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illumination curve of Example 6 of the optical imaging system of the present application;

[0038] Figure 13 This is a schematic structural diagram of the optical imaging system of this application;

[0039] Figures 14a to 14c They are respectively the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illumination curve of Example 7 of the optical imaging system of the present application;

[0040] Figure 15 This is a schematic structural diagram of the optical imaging system of this application;

[0041] Figures 16a to 16c They are respectively the on-axis chromatic aberration curve, astigmatism curve, distortion curve and relative illumination curve of Example 8 of the optical imaging system of the present application. DETAILED DESCRIPTION

[0042] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0043] It should be noted that in this specification, the terms "first," "second," "third," etc., are used solely to distinguish one feature from another and do not limit the features. Thus, the first lens discussed below could also be referred to as the second lens or the third lens without departing from the teachings of this application.

[0044] It should also be understood that the terms "comprises," "including," "having," "includes," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application." And, the term "exemplary" is intended to refer to an example or illustration.

[0045] In the drawings, the thickness, size, and shape of the lenses are slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical and aspherical surfaces shown in the drawings are provided by way of example. That is, the shapes of the spherical and aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0046] In this application, the paraxial region refers to the region near the optical axis. If a lens surface is convex and the location of the convex surface is undefined, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the location of the concave surface is undefined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the far beam surface of the lens, and the surface of each lens closest to the imaging plane is called the near beam surface of the lens.

[0047] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and will not be interpreted in an idealized or overly formal manner unless expressly defined as such herein.

[0048] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present application can be combined with each other. The features, principles and other aspects of the present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0049] Exemplary embodiments

[0050] An exemplary visual optical system of the present application includes: a first element group, a second lens, a third lens, and a light source; wherein, the first element group, the second lens, and the third lens are arranged in sequence along the optical axis from the human eye side to the light source position; wherein, the second lens has a positive optical power; wherein, the first element group includes a first lens, a reflective polarizing element, and a quarter-wave plate; wherein, the first lens, the reflective polarizing element, the quarter-wave plate, the second lens, and the third lens have a far-light surface away from the light source and a near-light surface close to the light source. In an embodiment of the present application, through the mutual cooperation among the partial reflection layer, the quarter-wave plate, and the reflective polarizing element, a circularly polarized light of a certain rotation direction emitted by the light source becomes a linearly polarized light in a specific direction after passing through the partial reflection layer and the quarter-wave plate, and after being reflected by the reflective polarizing element, it passes through the quarter-wave plate and the partial reflection layer again and is reflected into a circularly polarized light with a rotation direction opposite to that of the original incident light. Therefore, the linearly polarized light formed after passing through the wave plate for the third time can smoothly pass through the polarizing element and reach the human eye, realizing the folding of the optical path, thereby shortening the total optical length. The second lens is designed with a positive optical power, which is convenient for converging light and is beneficial to reducing the element size and further reducing the volume of the visual optical system device. The third lens is used to flexibly compensate for the distortion and chromatic aberration generated by the front optical element group, and further optimize the aberration to improve the imaging quality.

[0051] In an embodiment of the present application, the effective focal length f of the optical system, the effective focal length f2 of the second lens, and half of the maximum field angle Semi-FOV of the visual optical system satisfy: 2 < f2 / (f × tan(Semi-FOV)) < 6. In an embodiment of the present application, by restricting the relationship between the focal length of the second lens, the system focal length, and the half field angle, it is convenient for the system focal length distribution, is beneficial to the design of a small focal length and a large field, and can restrict the system image height to a certain extent, which is convenient for the selection of the light source size. More specifically, the effective focal length f of the optical system, the effective focal length f2 of the second lens, and half of the maximum field angle Semi-FOV of the visual optical system satisfy: 2.01 < f2 / (f × tan(Semi-FOV)) < 5.99.

[0052] The exemplary visual optical system of the present application includes: a first element group, a second lens, a third lens, and a light source; wherein, the first element group, the second lens, and the third lens are arranged in sequence along the optical axis from the human eye side to the light source position; wherein, both the first element group and the second lens have positive optical powers; wherein, the first element group includes a first lens, a reflective polarizing element, and a quarter-wave plate; wherein, the first lens, the reflective polarizing element, the quarter-wave plate, the second lens, and the third lens have a far-light surface away from the light source and a near-light surface close to the light source; wherein, at least one of the near-light surfaces of the first lens and the second lens has a partial reflection layer. In the embodiments of the present application, based on the polarization principle among the reflective polarizing element, the quarter-wave plate, and the partial reflection layer, an optical path folding mode is achieved through optical lenses, effectively shortening the total length of the optical system. Among them, the first and second lenses have positive optical powers, which is convenient for light beam convergence and is beneficial to reducing the screen height and the size of components. At the same time, a third lens is added to increase the adjustment and optimization space for system aberrations such as distortion and chromatic aberration, improve the image quality, and enhance the user's visual experience.

[0053] In an embodiment of the present application, the combined focal length FG12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens, the central thickness CT1 of the first lens on the optical axis, and the air gap T12 between the first lens and the second lens on the optical axis satisfy: 3.0 < FG12 / (CT1 + T12) < 12. In the embodiments of the present application, by controlling the combined focal length of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens, the central thickness of one lens, and the air gap between the first and second lenses, it is beneficial to control the molding and assembly strength of one lens, further control the total length of the optical design while avoiding the assembly interference between the first and second lenses, and at the same time, cooperating with the focal length control is beneficial to expanding the field of view angle as much as possible and enhancing the user's visual immersion experience. More specifically, the combined focal length FG12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens, the central thickness CT1 of the first lens on the optical axis, and the air gap T12 between the first lens and the second lens on the optical axis satisfy:

[0054] 3.01 < FG12 / (CT1 + T12) < 11.99.

[0055] In an exemplary embodiment of the present application, the axial distance SAG21 between the intersection of the second lens' high-beam surface and the optical axis and the vertex of the effective radius of the second lens' high-beam surface, and the axial distance SAG22 between the intersection of the second lens' low-beam surface and the optical axis and the vertex of the effective radius of the second lens' low-beam surface satisfy: -1 < (SAG21 + SAG22) / (SAG21 - SAG22) < 5.5. In the embodiments of the present application, by controlling the axial distances between the intersections of the object and image sides of the second lens with the optical axis and the vertices of the effective radii, on the one hand, the shape of the second lens can be controlled, which is beneficial for lens molding and assembly specifications, and on the other hand, it is beneficial for restricting the center thickness of the lens and ensuring the assembly strength. More specifically, the axial distance SAG21 between the intersection of the second lens' high-beam surface and the optical axis and the vertex of the effective radius of the second lens' high-beam surface, and the axial distance SAG22 between the intersection of the second lens' low-beam surface and the optical axis and the vertex of the effective radius of the second lens' low-beam surface satisfy: -0.99 < (SAG21 + SAG22) / (SAG21 - SAG22) < 5.49.

[0056] In an exemplary embodiment of the present application, the axial distance SAG31 between the intersection of the third lens' high-beam surface and the optical axis and the vertex of the effective radius of the third lens' high-beam surface, and the axial distance SAG32 between the intersection of the third lens' low-beam surface and the optical axis and the vertex of the effective radius of the third lens' low-beam surface satisfy: -2.5 < (SAG31 + SAG32) / (SAG31 - SAG32) < 9.0. In the embodiments of the present application, by controlling the axial distances between the intersections of the object and image sides of the third lens with the optical axis and the vertices of the effective radii, it is convenient to control the center thickness and shape of the third lens, which is beneficial for lens molding, ensuring the assembly strength, and avoiding interference with the display screen during assembly. More specifically, the axial distance SAG31 between the intersection of the third lens' high-beam surface and the optical axis and the vertex of the effective radius of the third lens' high-beam surface, and the axial distance SAG32 between the intersection of the third lens' low-beam surface and the optical axis and the vertex of the effective radius of the third lens' low-beam surface satisfy: -2.49 < (SAG31 + SAG32) / (SAG31 - SAG32) < 8.99.

[0057] In an exemplary embodiment of the present application, the Abbe number V1 of the first lens, the refractive index N1 of the first lens, the Abbe number V3 of the third lens, and the refractive index N3 of the third lens satisfy: 59 < V1 / N1 + V3 / N3 < 95. In the embodiments of the present application, by restricting the relationship between the Abbe number and the refractive index of the first lens and the third lens, it is beneficial to select appropriate material combinations to optimize or eliminate chromatic aberration phenomena such as abnormal red, green, and blue edges in the marginal field of view, and improve the image quality of the optical system. More specifically, the Abbe number V1 of the first lens, the refractive index N1 of the first lens, the Abbe number V3 of the third lens, and the refractive index N3 of the third lens satisfy: 59.01 < V1 / N1 + V3 / N3 < 94.99.

[0058] In an exemplary embodiment of the present application, the radius of curvature R5 of the far-light surface of the third lens, the radius of curvature R6 of the near-light surface of the third lens, and the combined focal length f23 of the second lens and the third lens satisfy: 0.5 < (R5 + R6) / f23 < 4.0. In an embodiment of the present application, by controlling the ratio of the radii of curvature on both sides of the third lens and the combined focal length of the second lens and the third lens, on the one hand, the shape of the third lens is constrained, which is beneficial to reducing the sensitivity of the third lens. On the other hand, it is convenient for BFL control and further shortens the length of the visual optical system device. More specifically, the radius of curvature R5 of the far-light surface of the third lens, the radius of curvature R6 of the near-light surface of the third lens, and the combined focal length f23 of the second lens and the third lens satisfy: 0.51 < (R5 + R6) / f23 < 4.00.

[0059] In an exemplary embodiment of the present application, the central thickness CT2 of the second lens on the optical axis, and the combined focal length FG12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens satisfy: 2.0 < FG12 / CT2 < 6.2. In an embodiment of the present application, by controlling the ratio of the combined focal length of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens to the central thickness of the second lens, it helps to control the thickness of the first lens and the polarizing element when the exit pupil distance is fixed, which is beneficial to film layer adhesion and assembly gap control. When the exit pupil size is determined, it is beneficial to the large field of view design and enhances the visual immersion experience. More specifically, the central thickness CT2 of the second lens on the optical axis, and the combined focal length FG12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens satisfy: 2.01 < FG12 / CT2 < 6.19.

[0060] In an exemplary embodiment of the present application, the Abbe number Vi of the i-th lens, and the maximum refractive index Nmax among the first lens, the reflective polarizing element, the quarter-wave plate, the second lens, and the third lens satisfy: 1 < Vi / 10 / Nmax < 5; where i = 1, 2, or 3. In an embodiment of the present application, by controlling the ratio of the Abbe number of each lens to the maximum refractive index, it is beneficial to the selection of materials with appropriate dispersion coefficients and refractive indices. Selecting a low-refractive-index material under the condition of controlling the dispersion coefficient is beneficial to reducing the material birefringence effect, optimizing the system dispersion and artifact phenomena, improving the polarization efficiency, and reducing the light energy loss. More specifically, the Abbe number Vi of the i-th lens, and the maximum refractive index Nmax among the first lens, the reflective polarizing element, the quarter-wave plate, the second lens, and the third lens satisfy: 1.01 < Vi / 10 / Nmax < 4.99.

[0061] In an exemplary embodiment of the present application, the on-axis distance TD from the far-light surface of the first lens to the far-light surface of the last lens, and the combined focal length FG12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens satisfy: 1 < FG12 / TD < 2.3. In an embodiment of the present application, by controlling the ratio of the combined focal length of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens to the on-axis distance from the far-light surface of the first lens to the near-light surface of the last lens, it is beneficial to achieve a design of the largest possible field angle while controlling the total length of the optical system, enhance the visual immersion experience, and facilitate the lightweight of the visual optical system device. More specifically, the on-axis distance TD from the far-light surface of the first lens to the far-light surface of the last lens, and the combined focal length FG12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens satisfy: 1.01 < FG12 / TD < 2.29.

[0062] In an exemplary embodiment of the present application, the on-axis distance TD from the far-light surface of the first lens to the far-light surface of the last lens, the central thickness CT1 of the first lens on the optical axis, and the central thickness CT3 of the third lens on the optical axis satisfy: 7.0 < TD / CT1 + TD / CT3 < 28.0. In an embodiment of the present application, by controlling the on-axis distance from the far-light surface of the first lens to the near-light surface of the last lens and the relationship between the thicknesses of the first and third lenses, it is possible to control the lens thickness while restricting the total length of the optical system, which is beneficial to the molding and assembly strength of the first and third lenses. On the other hand, it is beneficial to control the air gap between the lenses and ensure the lens assembly interval. More specifically, the on-axis distance TD from the far-light surface of the first lens to the far-light surface of the last lens, the central thickness CT1 of the first lens on the optical axis, and the central thickness CT3 of the third lens on the optical axis satisfy: 7.01 < TD / CT1 + TD / CT3 < 27.99.

[0063] In an exemplary embodiment of the present application, the radius of curvature R3 of the far-light surface of the second lens and the radius of curvature R4 of the near-light surface of the second lens satisfy: |R3 / R4| < 6.0. In an embodiment of the present application, by controlling the radii of curvature on both the object and image sides of the second lens, it is beneficial to limit the lens surface shape and avoid the risks of molding, assembly, and marginal aberration in the extreme shape. More specifically, the radius of curvature R3 of the far-light surface of the second lens and the radius of curvature R4 of the near-light surface of the second lens satisfy: |R3 / R4| < 5.99.

[0064] In an exemplary embodiment of the present application, the radius of curvature R4 of the far-light surface of the second lens and the effective focal length f2 of the second lens satisfy: |f2 / R4| < 3.0. In an embodiment of the present application, by restricting the radius of curvature of the near-light surface of the second lens and the effective focal length of the second lens, the shape of the second lens is constrained to a certain extent, which is beneficial to reducing the sensitivity of the second lens and thus improving the assembly yield. More specifically, the radius of curvature R4 of the far-light surface of the second lens and the effective focal length f2 of the second lens satisfy: |f2 / R4| < 2.99.

[0065] In an exemplary embodiment of the present application, the effective focal length f of the optical system and the central thickness CT2 of the second lens on the optical axis satisfy: 2.0 < f / CT2 < 5.5. By controlling the focal length of the system and the central thickness of the second lens, the shape of the second lens is further constrained, which is beneficial to controlling the molding of the second lens and ensuring the assembly strength. More specifically, the effective focal length f of the optical system and the central thickness CT2 of the second lens on the optical axis satisfy: 2.01 < f / CT2 < 5.49.

[0066] In an exemplary embodiment of the present application, the near-light surface of the quarter-wave plate is at least partially in contact with the far-light surface of the first lens. In an embodiment of the present application, the quarter-wave plate is attached to the far-light surface of the first lens, which can achieve the change of the polarization state of the light beam and expand the folded optical path as much as possible, increasing the space for aberration optimization.

[0067] In an exemplary embodiment of the present application, the far-light surface of the reflective polarizing element is at least partially in contact with the near-light surface of the first lens; the near-light surface of the reflective polarizing element is at least partially in contact with the far-light surface of the quarter-wave plate. In an embodiment of the present application, the reflective polarizing element and the quarter-wave plate are combined into one film, reducing the number of attachment surfaces in the assembly process, which is beneficial to improving the attachment efficiency. Attached to the near-light surface of the first lens, it participates in the folding process of the system optical path.

[0068] In this exemplary embodiment, the far-light surface and the near-light surface of any one of the first lens E1 to the third lens E3 are aspherical surfaces, and the surface profile x of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0069]

[0070] where x is the sagitta distance from the vertex of the aspherical surface at the position with a height of h along the optical axis direction; c is the paraxial curvature of the aspherical surface, c = 1 / R (that is, the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1); k is the conic coefficient; Ai is the correction coefficient of the i-th order of the aspherical surface.

[0071] In this exemplary embodiment, the visual optical system may further include an aperture. The aperture may be positioned appropriately as needed, for example, between the high beam and the first lens. Optionally, the visual optical system may further include a filter for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging surface.

[0072] The visual optical system according to the above-described embodiment of the present application can utilize multiple lenses, such as the three lenses described above. By rationally allocating the optical power, surface shape, center thickness of each lens, and the on-axis spacing between lenses, the optical imaging system is made smaller in size and volume, with a wide imaging range and high imaging quality, while ensuring the ultra-thinness of VR.

[0073] In an exemplary embodiment, at least one of the mirror surfaces of each lens is an aspherical mirror surface, that is, at least one of the mirror surfaces from the far light surface of the first lens to the near light surface of the third lens is an aspherical mirror surface. The characteristics of an aspherical lens are: the curvature changes continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens with a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has a better curvature radius characteristic, and has the advantages of improving distortion aberration and improving astigmatism aberration. After adopting an aspherical lens, the aberration that occurs during imaging can be eliminated as much as possible, thereby improving the imaging quality. Optionally, at least one of the far light surface and the near light surface of each lens of the first lens, the second lens and the third lens is an aspherical mirror surface. Optionally, the far light surface and the near light surface of each lens of the first lens, the second lens and the third lens are both aspherical mirror surfaces.

[0074] However, those skilled in the art will appreciate that the number of lenses comprising the optical imaging system can be varied to achieve the various results and advantages described herein without departing from the technical solutions claimed in this application. For example, although three lenses are used as an example in the embodiments, the visual optical system is not limited to including three lenses and can include other numbers of lenses if desired.

[0075] Specific embodiments of the visual optical system applicable to the above-mentioned embodiments will be further described below with reference to the accompanying drawings. Specific embodiment 1

[0077] Figure 1This is a schematic diagram of the structure of Example 1 of the visual optical system of the present application, which includes: a first element group, a second lens E2, a third lens E3, and a light source; wherein the first element group, the second lens E2, and the third lens E3 are arranged in sequence along the optical axis from the human eye side to the position of the light source S9; wherein the second lens has positive optical power; wherein the first element group includes the first lens E1, a reflective polarizer RP, and a quarter-wave plate QWP; wherein the first lens E1, the reflective polarizer RP, the quarter-wave plate QWP, the second lens E2, and the third lens E3 have a far light surface away from the light source S9 and a near light surface close to the light source; wherein the quarter-wave plate QWP is attached to and partially contacts the far light surface of the first lens E1.

[0078] Among them, the light source emits a circularly polarized light, which passes through the third lens, the second lens, the first lens and the quarter-wave plate to become linearly polarized light. After passing through the reflective polarization element, it is reflected, then passes through the quarter-wave plate and the first lens, and is reflected by the partial reflective layer on the first lens. Finally, it passes through the first lens, the quarter-wave plate, and the reflective polarization element and enters the human eye, realizing the folding of the light path and thus shortening the total optical length.

[0079] As shown in Table 1, it is a basic parameter table of the visual optical system of Example 1, wherein the units of the curvature radius, thickness, and focal length are all millimeters (mm).

[0080]

[0081] Table 1

[0082] As shown in Table 2, in Example 1, the total effective focal length f of the visual optical system is 24.80 mm, and half of the maximum field angle of the visual optical system, semi-fov, is 53.00°.

[0083]

[0084] Table 2

[0085] The visual optical system in Example 1 satisfies:

[0086] f2 / (f×tan(Semi-FOV))=2.50, where f is the effective focal length of the optical system, f2 is the effective focal length of the second lens, and Semi-FOV is half of the maximum field of view of the visual optical system.

[0087] (SAG21+SAG22) / (SAG21-SAG22)=0.65, where SAG21 is the on-axis distance between the intersection of the second lens's far light surface and the optical axis and the vertex of the effective radius of the second lens's far light surface; SAG22 is the on-axis distance between the intersection of the second lens's near light surface and the optical axis and the vertex of the effective radius of the second lens' near light surface.

[0088] (SAG31+SAG32) / (SAG31-SAG32)=-1.97, where SAG31 is the on-axis distance between the intersection of the third lens' far light surface and the optical axis and the vertex of the effective radius of the third lens' far light surface; SAG32 is the on-axis distance between the intersection of the third lens' near light surface and the optical axis and the vertex of the effective radius of the third lens' near light surface.

[0089] V1 / N1+V3 / N3=59.76, where V1 is the Abbe number of the first lens, N1 is the refractive index of the first lens, V3 is the Abbe number of the third lens, and N3 is the refractive index of the third lens.

[0090] (R5+R6) / f23=3.43, where R5 is the curvature radius of the far beam surface of the third lens, R6 is the curvature radius of the near beam surface of the third lens, and f23 is the combined focal length of the second lens and the third lens.

[0091] FG12 / CT2=2.48, where CT2 is the center thickness of the second lens on the optical axis, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0092] FG12 / (CT1+T12)=7.82, where FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens; CT1 is the center thickness of the first lens on the optical axis; and T12 is the air gap between the first lens and the second lens on the optical axis.

[0093] FG12 / TD=1.72, where TD is the on-axis distance from the far light surface of the first lens to the near light surface of the last lens, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0094] TD / CT1+TD / CT3=17.32, where TD is the on-axis distance from the far beam surface of the first lens to the far beam surface of the last lens, CT1 is the center thickness of the first lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis.

[0095] |R3 / R4|=0.23, where R3 is the curvature radius of the far beam surface of the second lens, and R4 is the curvature radius of the near beam surface of the second lens.

[0096] |f2 / R4|=0.45, where R4 is the curvature radius of the near optical surface of the second lens, and f2 is the effective focal length of the second lens.

[0097] f / CT2=2.43, where f is the effective focal length of the optical system, and CT2 is the center thickness of the second lens on the optical axis.

[0098] i=1, Vi / 10 / Nmax=3.81; i=2, Vi / 10 / Nmax=3.74; i=3, Vi / 10 / Nmax=1.57; where Vi is the Abbe number of the i-th lens, and Nmax is the lens with the largest refractive index among the first lens, reflective polarizer, quarter-wave plate, second lens, and third lens.

[0099] In Example 1, the outer side surface and the inner side surface of any one of the first lens E1 to the third lens E3 are aspherical surfaces. Table 3 shows the high-order coefficients A4, A6, A8, A10, and A12 of the aspherical mirror surfaces S4, S5, S6, S7, and S8 that can be used in Example 1.

[0100]

[0101]

[0102] Table 3

[0103] Figure 2a The axial chromatic aberration curve of the visual optical system of Example 1 is shown, which indicates the deviation of the convergence point of light of different wavelengths after passing through the lens. Figure 2b The astigmatism curve of the visual optical system of Example 1 is shown, which indicates the meridional field curvature and the sagittal field curvature. Figure 2c The distortion curve of the visual optical system of Example 1 is shown, which represents the distortion value under different viewing angles. Figures 2a to 2c As shown, the visual optical system provided in Example 1 can achieve good imaging quality. Specific embodiment 2

[0105] Figure 3 This is a schematic diagram of the structure of Example 2 of the visual optical system of the present application, which includes: a first element group, a second lens E2, a third lens E3, and a light source; wherein the first element group, the second lens E2, and the third lens E3 are arranged in sequence along the optical axis from the human eye side to the position of the light source S9; wherein the second lens has positive optical power; wherein the first element group includes the first lens E1, a reflective polarizer RP, and a quarter-wave plate QWP; wherein the first lens E1, the reflective polarizer RP, the quarter-wave plate QWP, the second lens E2, and the third lens E3 have a far light surface away from the light source S9 and a near light surface close to the light source; wherein the quarter-wave plate QWP is attached to and partially contacts the far light surface of the first lens E1.

[0106] Among them, the light source emits a circularly polarized light, which passes through the third lens, the second lens, the first lens and the quarter-wave plate to become linearly polarized light. After passing through the reflective polarization element, it is reflected, then passes through the quarter-wave plate and the first lens, and is reflected by the partial reflective layer on the first lens. Finally, it passes through the first lens, the quarter-wave plate, and the reflective polarization element and enters the human eye, realizing the folding of the light path and thus shortening the total optical length.

[0107] As shown in Table 4, it is a basic parameter table of the visual optical system of Example 2, wherein the units of the curvature radius, thickness, and focal length are all millimeters (mm).

[0108]

[0109]

[0110] Table 4

[0111] As shown in Table 5, in Example 2, the total effective focal length of the visual optical system is f=25.88 mm, and half of the maximum field angle of the visual optical system is semi-fov=53.00°.

[0112]

[0113] Table 5

[0114] The visual optical system in Example 2 satisfies:

[0115] f2 / (f×tan(Semi-FOV))=2.92, where f is the effective focal length of the optical system, f2 is the effective focal length of the second lens, and Semi-FOV is half of the maximum field of view of the visual optical system.

[0116] (SAG21+SAG22) / (SAG21-SAG22)=2.76, where SAG21 is the on-axis distance between the intersection of the second lens's far light surface and the optical axis and the vertex of the effective radius of the second lens's far light surface; and SAG22 is the on-axis distance between the intersection of the second lens's near light surface and the optical axis and the vertex of the effective radius of the second lens' near light surface.

[0117] (SAG31+SAG32) / (SAG31-SAG32)=3.84, where SAG31 is the on-axis distance between the intersection of the third lens' far light surface and the optical axis and the vertex of the effective radius of the third lens' far light surface; SAG32 is the on-axis distance between the intersection of the third lens' near light surface and the optical axis and the vertex of the effective radius of the third lens' near light surface.

[0118] V1 / N1+V3 / N3=94.50, where V1 is the Abbe number of the first lens, N1 is the refractive index of the first lens, V3 is the Abbe number of the third lens, and N3 is the refractive index of the third lens.

[0119] (R5+R6) / f23=1.00, where R5 is the curvature radius of the far beam surface of the third lens, R6 is the curvature radius of the near beam surface of the third lens, and f23 is the combined focal length of the second lens and the third lens.

[0120] FG12 / CT2=4.86, where CT2 is the center thickness of the second lens on the optical axis, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0121] FG12 / (CT1+T12)=7.50, where FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens; CT1 is the center thickness of the first lens on the optical axis; and T12 is the air gap between the first lens and the second lens on the optical axis.

[0122] FG12 / TD=1.78, where TD is the on-axis distance from the far light surface of the first lens to the near light surface of the last lens, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0123] TD / CT1+TD / CT3=7.89, where TD is the on-axis distance from the far beam surface of the first lens to the far beam surface of the last lens, CT1 is the center thickness of the first lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis.

[0124] |R3 / R4|=0.51, where R3 is the curvature radius of the far beam surface of the second lens, and R4 is the curvature radius of the near beam surface of the second lens.

[0125] |f2 / R4|=1.06, where R4 is the curvature radius of the near optical surface of the second lens, and f2 is the effective focal length of the second lens.

[0126] f / CT2=4.53, where f is the effective focal length of the optical system, and CT2 is the center thickness of the second lens on the optical axis.

[0127] i=1, Vi / 10 / Nmax=4.69; i=2, Vi / 10 / Nmax=4.69; i=3, Vi / 10 / Nmax=4.69; where Vi is the Abbe number of the i-th lens, and Nmax is the lens with the largest refractive index among the first lens, reflective polarizer, quarter-wave plate, second lens, and third lens.

[0128] In Example 2, the outer side surface and the inner side surface of any one of the first lens E1 to the third lens E3 are aspherical surfaces. Table 6 shows the high-order coefficients A4, A6, A8, A10, and A12 of the aspherical mirror surfaces S4, S5, S6, S7, and S8 that can be used in Example 2.

[0129] Face number A4 A6 A8 A10 A12 S4 2.9692E+01 5.3517E-02 8.9909E-02 -4.6454E-03 -2.6698E-02 S5 3.3362E+01 -1.2714E-01 -1.3794E+00 -1.3337E+00 9.9695E-02 S6 2.4967E+01 -3.3522E+00 -1.5650E+00 -8.5435E-02 -4.6075E-03 S7 4.0324E+01 -1.7889E+00 -2.3521E+00 -2.0050E+00 3.7183E-01 S8 2.2688E+01 -2.5026E+00 -3.3178E-01 3.2501E-01 8.2043E-03

[0130] Table 6

[0131] Figure 4a The axial chromatic aberration curve of the visual optical system of Example 2 is shown, which indicates the deviation of the convergence point of light of different wavelengths after passing through the lens. Figure 4b The astigmatism curve of the visual optical system of Example 2 is shown, which indicates the meridional field curvature and the sagittal field curvature. Figure 4c The distortion curve of the visual optical system of Example 2 is shown, which represents the distortion value under different viewing angles. Figures 4a to 4c As shown, the visual optical system provided in Example 2 can achieve good imaging quality. Specific embodiment 3

[0133] Figure 5 This is a schematic diagram of the structure of Example 3 of the visual optical system of the present application, which includes: a first element group, a second lens E2, a third lens E3, and a light source; wherein the first element group, the second lens E2, and the third lens E3 are arranged in sequence along the optical axis from the human eye side to the position of the light source S9; wherein the second lens has positive optical power; wherein the first element group includes the first lens E1, a reflective polarizer RP, and a quarter-wave plate QWP; wherein the first lens E1, the reflective polarizer RP, the quarter-wave plate QWP, the second lens E2, and the third lens E3 have a far light surface away from the light source S9 and a near light surface close to the light source; wherein the quarter-wave plate QWP is attached to and partially contacts the far light surface of the first lens E1.

[0134] Among them, the light source emits a circularly polarized light, which passes through the third lens, the second lens, the first lens and the quarter-wave plate to become linearly polarized light. After passing through the reflective polarization element, it is reflected, then passes through the quarter-wave plate and the first lens, and is reflected by the partial reflective layer on the first lens. Finally, it passes through the first lens, the quarter-wave plate, and the reflective polarization element and enters the human eye, realizing the folding of the light path and thus shortening the total optical length.

[0135] As shown in Table 7, it is a basic parameter table of the visual optical system of Example 3, wherein the units of the curvature radius, thickness, and focal length are all millimeters (mm).

[0136]

[0137] Table 7

[0138] As shown in Table 8, in Example 3, the total effective focal length of the visual optical system is f=25.89 mm, and half of the maximum field angle of the visual optical system is semi-fov=53.00°.

[0139]

[0140] Table 8

[0141] The visual optical system in Example 3 satisfies:

[0142] f2 / (f×tan(Semi-FOV))=3.56, where f is the effective focal length of the optical system, f2 is the effective focal length of the second lens, and Semi-FOV is half of the maximum field of view of the visual optical system.

[0143] (SAG21+SAG22) / (SAG21-SAG22)=5.06, where SAG21 is the on-axis distance between the intersection of the second lens's far light surface and the optical axis and the vertex of the effective radius of the second lens's far light surface; and SAG22 is the on-axis distance between the intersection of the second lens's near light surface and the optical axis and the vertex of the effective radius of the second lens' near light surface.

[0144] (SAG31+SAG32) / (SAG31-SAG32)=3.84, where SAG31 is the on-axis distance between the intersection of the third lens' far light surface and the optical axis and the vertex of the effective radius of the third lens' far light surface; SAG32 is the on-axis distance between the intersection of the third lens' near light surface and the optical axis and the vertex of the effective radius of the third lens' near light surface.

[0145] V1 / N1+V3 / N3=94.50, where V1 is the Abbe number of the first lens, N1 is the refractive index of the first lens, V3 is the Abbe number of the third lens, and N3 is the refractive index of the third lens.

[0146] (R5+R6) / f23=0.86, where R5 is the curvature radius of the far beam surface of the third lens, R6 is the curvature radius of the near beam surface of the third lens, and f23 is the combined focal length of the second lens and the third lens.

[0147] FG12 / CT2=5.53, where CT2 is the center thickness of the second lens on the optical axis, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0148] FG12 / (CT1+T12)=6.47, where FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens; CT1 is the center thickness of the first lens on the optical axis; and T12 is the air gap between the first lens and the second lens on the optical axis.

[0149] FG12 / TD=1.70, where TD is the on-axis distance from the far light surface of the first lens to the near light surface of the last lens, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0150] TD / CT1+TD / CT3=7.22, where TD is the on-axis distance from the far beam surface of the first lens to the far beam surface of the last lens, CT1 is the center thickness of the first lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis.

[0151] |R3 / R4|=0.70, where R3 is the curvature radius of the far beam surface of the second lens, and R4 is the curvature radius of the near beam surface of the second lens.

[0152] |f2 / R4|=2.79, where R4 is the curvature radius of the near optical surface of the second lens, and f2 is the effective focal length of the second lens.

[0153] f / CT2=5.05, where f is the effective focal length of the optical system, and CT2 is the center thickness of the second lens on the optical axis.

[0154] i=1, Vi / 10 / Nmax=4.69; i=2, Vi / 10 / Nmax=4.69; i=3, Vi / 10 / Nmax=4.69; where Vi is the Abbe number of the i-th lens, and Nmax is the lens with the largest refractive index among the first lens, reflective polarizer, quarter-wave plate, second lens, and third lens.

[0155] In Example 3, both the outer and inner side surfaces of any one of the first lens E1 to the third lens E3 are aspherical surfaces. Table 9 shows the high-order coefficients A4, A6, A8, A10, and A12 of the aspherical mirror surfaces S4, S5, S6, S7, and S8 that can be used in Example 3.

[0156] Face number A4 A6 A8 A10 A12 S4 3.1490E+01 4.5497E-02 7.9064E-02 -1.6946E-03 -2.8200E-02 S5 3.2659E+01 -3.9864E+00 -2.7109E+00 -1.0676E+00 8.9876E-01 S6 2.5674E+01 -6.0140E+00 -2.4047E+00 8.7843E-01 1.6439E-02 S7 2.2899E+01 -4.4343E+00 -3.2006E-01 -1.7395E-01 1.9625E-02 S8 4.6432E+01 -2.0976E+00 -2.2310E+00 -5.0668E+00 -1.0550E+00

[0157] Table 9

[0158] Figure 6a The axial chromatic aberration curve of the visual optical system of Example 3 is shown, which indicates the deviation of the convergence point of light of different wavelengths after passing through the lens. Figure 6b The astigmatism curve of the visual optical system of Example 3 is shown, which indicates the meridional field curvature and the sagittal field curvature. Figure 6c The distortion curve of the visual optical system of Example 3 is shown, which represents the distortion value under different viewing angles. Figures 6a to 6c As shown, the visual optical system provided in Example 3 can achieve good imaging quality. Specific embodiment 4

[0160] Figure 7 This is a schematic diagram of the structure of Example 4 of the visual optical system of the present application, which includes: a first element group, a second lens E2, a third lens E3, and a light source; wherein the first element group, the second lens E2, and the third lens E3 are arranged in sequence along the optical axis from the human eye side to the position of the light source S9; wherein the second lens has positive optical power; wherein the first element group includes the first lens E1, a reflective polarizer RP, and a quarter-wave plate QWP; wherein the first lens E1, the reflective polarizer RP, the quarter-wave plate QWP, the second lens E2, and the third lens E3 have a far light surface away from the light source S9 and a near light surface close to the light source; wherein the quarter-wave plate QWP is attached to and partially contacts the far light surface of the first lens E1.

[0161] Among them, the light source emits a circularly polarized light, which passes through the third lens, the second lens, the first lens and the quarter-wave plate to become linearly polarized light. After passing through the reflective polarization element, it is reflected, then passes through the quarter-wave plate and the first lens, and is reflected by the partial reflective layer on the first lens. Finally, it passes through the first lens, the quarter-wave plate, and the reflective polarization element and enters the human eye, realizing the folding of the light path and thus shortening the total optical length.

[0162] As shown in Table 10, it is a basic parameter table of the visual optical system of Example 4, wherein the units of the curvature radius, thickness, and focal length are all millimeters (mm).

[0163]

[0164] Table 10

[0165] As shown in Table 11, in Example 4, the total effective focal length f of the visual optical system is 25.89 mm, and half of the maximum field angle of the visual optical system, semi-fov, is 53.00°.

[0166]

[0167] Table 11

[0168] The visual optical system in Example 4 satisfies:

[0169] f2 / (f×tan(Semi-FOV))=2.74, where f is the effective focal length of the optical system, f2 is the effective focal length of the second lens, and Semi-FOV is half of the maximum field of view of the visual optical system.

[0170] (SAG21+SAG22) / (SAG21-SAG22)=1.17, where SAG21 is the on-axis distance between the intersection of the second lens's far light surface and the optical axis and the vertex of the effective radius of the second lens's far light surface; SAG22 is the on-axis distance between the intersection of the second lens's near light surface and the optical axis and the vertex of the effective radius of the second lens' near light surface.

[0171] (SAG31+SAG32) / (SAG31-SAG32)=3.02, where SAG31 is the on-axis distance between the intersection of the third lens' far light surface and the optical axis and the vertex of the effective radius of the third lens' far light surface; and SAG32 is the on-axis distance between the intersection of the third lens' near light surface and the optical axis and the vertex of the effective radius of the third lens' near light surface.

[0172] V1 / N1+V3 / N3=94.50, where V1 is the Abbe number of the first lens, N1 is the refractive index of the first lens, V3 is the Abbe number of the third lens, and N3 is the refractive index of the third lens.

[0173] (R5+R6) / f23=1.33, where R5 is the curvature radius of the far beam surface of the third lens, R6 is the curvature radius of the near beam surface of the third lens, and f23 is the combined focal length of the second lens and the third lens.

[0174] FG12 / CT2=5.55, where CT2 is the center thickness of the second lens on the optical axis, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0175] FG12 / (CT1+T12)=6.37, where FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens; CT1 is the center thickness of the first lens on the optical axis; and T12 is the air gap between the first lens and the second lens on the optical axis.

[0176] FG12 / TD=1.79, where TD is the on-axis distance from the far light surface of the first lens to the near light surface of the last lens, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0177] TD / CT1+TD / CT3=7.52, where TD is the on-axis distance from the far beam surface of the first lens to the far beam surface of the last lens, CT1 is the center thickness of the first lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis.

[0178] |R3 / R4|=0.30, where R3 is the curvature radius of the far beam surface of the second lens, and R4 is the curvature radius of the near beam surface of the second lens.

[0179] |f2 / R4|=0.37, where R4 is the curvature radius of the near optical surface of the second lens, and f2 is the effective focal length of the second lens.

[0180] f / CT2=5.30, where f is the effective focal length of the optical system, and CT2 is the center thickness of the second lens on the optical axis.

[0181] i=1, Vi / 10 / Nmax=4.69; i=2, Vi / 10 / Nmax=4.69; i=3, Vi / 10 / Nmax=4.69; where Vi is the Abbe number of the i-th lens, and Nmax is the lens with the largest refractive index among the first lens, reflective polarizer, quarter-wave plate, second lens, and third lens.

[0182] In Example 4, both the outer and inner side surfaces of any one of the first lens E1 to the third lens E3 are aspherical surfaces. Table 12 shows the high-order coefficients A4, A6, A8, A10, and A12 of the aspherical mirror surfaces S4, S5, S6, S7, and S8 that can be used in Example 4.

[0183] Face number A4 A6 A8 A10 A12 S4 2.9652E+01 1.1643E-01 9.4089E-02 -3.3439E-02 -3.6244E-02 S5 2.9925E+01 -8.6535E-01 -9.3872E-01 -8.1909E-01 -2.1812E-01 S6 2.7964E+01 -4.0841E+00 -1.7746E+00 -4.0432E-02 -4.3952E-01 S7 4.7125E+01 9.1219E-01 -1.5715E+00 -2.9776E+00 -9.0556E-01 S8 2.4406E+01 -8.5442E-01 -1.4073E+00 3.3137E-01 1.8678E-01

[0184] Table 12

[0185] Figure 8a The axial chromatic aberration curve of the visual optical system of Example 4 is shown, which indicates the deviation of the convergence point of light of different wavelengths after passing through the lens. Figure 8b The astigmatism curve of the visual optical system of Example 4 is shown, which indicates the meridional field curvature and the sagittal field curvature. Figure 8c The distortion curve of the visual optical system of Example 4 is shown, which represents the distortion value under different viewing angles. Figures 8a to 8c As shown, the visual optical system provided in Example 4 can achieve good imaging quality. Specific embodiment 5

[0187] Figure 9This is a schematic diagram of the structure of Example 5 of the visual optical system of the present application, which includes: a first element group, a second lens E2, a third lens E3, and a light source; wherein the first element group, the second lens E2, and the third lens E3 are arranged in sequence along the optical axis from the human eye side to the position of the light source S9; wherein the second lens has positive optical power; wherein the first element group includes the first lens E1, a reflective polarizer RP, and a quarter-wave plate QWP; wherein the first lens E1, the reflective polarizer RP, the quarter-wave plate QWP, the second lens E2, and the third lens E3 have a far light surface away from the light source S9 and a near light surface close to the light source; wherein the quarter-wave plate QWP is attached to and partially contacts the far light surface of the first lens E1.

[0188] Among them, the light source emits a circularly polarized light, which passes through the third lens, the second lens, the first lens and the quarter-wave plate to become linearly polarized light. After passing through the reflective polarization element, it is reflected, then passes through the quarter-wave plate and the first lens, and is reflected by the partial reflective layer on the first lens. Finally, it passes through the first lens, the quarter-wave plate, and the reflective polarization element and enters the human eye, realizing the folding of the light path and thus shortening the total optical length.

[0189] As shown in Table 13, it is a basic parameter table of the visual optical system of Example 5, wherein the units of the curvature radius, thickness, and focal length are all millimeters (mm).

[0190]

[0191]

[0192] Table 13

[0193] As shown in Table 14, in Example 5, the total effective focal length f of the visual optical system is 25.86 mm, and half of the maximum field angle of the visual optical system, semi-fov, is 53.00°.

[0194]

[0195] Table 14

[0196] The visual optical system in Example 5 satisfies:

[0197] f2 / (f×tan(Semi-FOV))=3.39, where f is the effective focal length of the optical system, f2 is the effective focal length of the second lens, and Semi-FOV is half of the maximum field of view of the visual optical system.

[0198] (SAG21+SAG22) / (SAG21-SAG22)=2.77, where SAG21 is the on-axis distance between the intersection of the second lens's far light surface and the optical axis and the vertex of the effective radius of the second lens's far light surface; SAG22 is the on-axis distance between the intersection of the second lens's near light surface and the optical axis and the vertex of the effective radius of the second lens' near light surface.

[0199] (SAG31+SAG32) / (SAG31-SAG32)=8.48, where SAG31 is the on-axis distance between the intersection of the third lens's far light surface and the optical axis and the vertex of the effective radius of the third lens' far light surface; SAG32 is the on-axis distance between the intersection of the third lens's near light surface and the optical axis and the vertex of the effective radius of the third lens' near light surface.

[0200] V1 / N1+V3 / N3=89.40, where V1 is the Abbe number of the first lens, N1 is the refractive index of the first lens, V3 is the Abbe number of the third lens, and N3 is the refractive index of the third lens.

[0201] (R5+R6) / f23=1.00, where R5 is the curvature radius of the far beam surface of the third lens, R6 is the curvature radius of the near beam surface of the third lens, and f23 is the combined focal length of the second lens and the third lens.

[0202] FG12 / CT2=4.76, where CT2 is the center thickness of the second lens on the optical axis, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0203] FG12 / (CT1+T12)=7.00, where FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens; CT1 is the center thickness of the first lens on the optical axis; and T12 is the air gap between the first lens and the second lens on the optical axis.

[0204] FG12 / TD=2.17, where TD is the on-axis distance from the far light surface of the first lens to the near light surface of the last lens, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0205] TD / CT1+TD / CT3=8.64, where TD is the on-axis distance from the far beam surface of the first lens to the far beam surface of the last lens, CT1 is the center thickness of the first lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis.

[0206] |R3 / R4|=0.58, where R3 is the curvature radius of the far beam surface of the second lens, and R4 is the curvature radius of the near beam surface of the second lens.

[0207] |f2 / R4|=1.81, where R4 is the curvature radius of the near optical surface of the second lens, and f2 is the effective focal length of the second lens.

[0208] f / CT2=4.23, where f is the effective focal length of the optical system, and CT2 is the center thickness of the second lens on the optical axis.

[0209] i=1, Vi / 10 / Nmax=4.31; i=2, Vi / 10 / Nmax=4.42; i=3, Vi / 10 / Nmax=4.54; where Vi is the Abbe number of the i-th lens, and Nmax is the lens with the largest refractive index among the first lens, reflective polarizer, quarter-wave plate, second lens, and third lens.

[0210] In Example 5, both the outer and inner side surfaces of any one of the first lens E1 to the third lens E3 are aspherical surfaces. Table 15 shows the high-order coefficients A4, A6, A8, A10, and A12 of the aspherical mirror surfaces S4, S5, S6, S7, and S8 that can be used in Example 5.

[0211] Face number A4 A6 A8 A10 A12 S4 2.9819E+01 1.8128E-01 8.8937E-02 1.8178E-02 6.0198E-03 S5 2.9225E+01 6.0461E-01 -1.2263E-01 -1.3903E-01 1.2279E-01 S6 3.4508E+01 -9.1711E-01 -3.5934E-01 6.6848E-03 -5.3432E-02 S7 2.4187E+01 3.6165E-02 5.4850E-01 1.7995E-01 -1.6702E-01 S8 1.9432E+01 -1.2526E-01 1.6318E-01 -2.5373E-02 -3.0383E-02

[0212] Table 15

[0213] Figure 10a The axial chromatic aberration curve of the visual optical system of Example 5 is shown, which indicates the deviation of the convergence point of light of different wavelengths after passing through the lens. Figure 10b The astigmatism curve of the visual optical system of Example 5 is shown, which indicates the meridional field curvature and the sagittal field curvature. Figure 10c The distortion curve of the visual optical system of Example 5 is shown, which represents the distortion value under different viewing angles. Figures 10a to 10c As shown, the visual optical system provided in Example 5 can achieve good imaging quality. Specific embodiment 6

[0215] Figure 11 This is a schematic diagram of the structure of Example 6 of the visual optical system of the present application, which includes: a first element group, a second lens E2, a third lens E3, and a light source; wherein the first element group, the second lens E2, and the third lens E3 are arranged in sequence along the optical axis from the human eye side to the position of the light source S9; wherein the second lens has positive optical power; wherein the first element group includes the first lens E1, a reflective polarizer RP, and a quarter-wave plate QWP; wherein the first lens E1, the reflective polarizer RP, the quarter-wave plate QWP, the second lens E2, and the third lens E3 have a far light surface away from the light source S9 and a near light surface close to the light source; wherein the quarter-wave plate QWP is attached to and partially contacts the far light surface of the first lens E1.

[0216] Among them, the light source emits a circularly polarized light, which passes through the third lens, the second lens, the first lens and the quarter-wave plate to become linearly polarized light. After passing through the reflective polarization element, it is reflected, then passes through the quarter-wave plate and the first lens, and is reflected by the partial reflective layer on the first lens. Finally, it passes through the first lens, the quarter-wave plate, and the reflective polarization element and enters the human eye, realizing the folding of the light path and thus shortening the total optical length.

[0217] As shown in Table 16, it is a basic parameter table of the visual optical system of Example 6, wherein the units of the curvature radius, thickness, and focal length are all millimeters (mm).

[0218]

[0219] Table 16

[0220] As shown in Table 17, in Example 6, the total effective focal length f of the visual optical system is 25.89 mm, and half of the maximum field angle of the visual optical system, semi-fov, is 53.00°.

[0221]

[0222] Table 17

[0223] The visual optical system in Example 6 satisfies:

[0224] f2 / (f×tan(Semi-FOV))=2.44, where f is the effective focal length of the optical system, f2 is the effective focal length of the second lens, and Semi-FOV is half of the maximum field of view of the visual optical system.

[0225] (SAG21+SAG22) / (SAG21-SAG22)=3.48, where SAG21 is the on-axis distance between the intersection of the second lens's far light surface and the optical axis and the vertex of the effective radius of the second lens's far light surface; SAG22 is the on-axis distance between the intersection of the second lens's near light surface and the optical axis and the vertex of the effective radius of the second lens' near light surface.

[0226] (SAG31+SAG32) / (SAG31-SAG32)=2.31, where SAG31 is the on-axis distance between the intersection of the third lens's far light surface and the optical axis and the vertex of the effective radius of the third lens' far light surface; SAG32 is the on-axis distance between the intersection of the third lens's near light surface and the optical axis and the vertex of the effective radius of the third lens' near light surface.

[0227] V1 / N1+V3 / N3=94.50, where V1 is the Abbe number of the first lens, N1 is the refractive index of the first lens, V3 is the Abbe number of the third lens, and N3 is the refractive index of the third lens.

[0228] (R5+R6) / f23=1.79, where R5 is the curvature radius of the far beam surface of the third lens, R6 is the curvature radius of the near beam surface of the third lens, and f23 is the combined focal length of the second lens and the third lens.

[0229] FG12 / CT2=4.63, where CT2 is the center thickness of the second lens on the optical axis, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0230] FG12 / (CT1+T12)=3.34, where FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens; CT1 is the center thickness of the first lens on the optical axis; and T12 is the air gap between the first lens and the second lens on the optical axis.

[0231] FG12 / TD=1.11, where TD is the on-axis distance from the far light surface of the first lens to the near light surface of the last lens, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0232] TD / CT1+TD / CT3=13.55, where TD is the on-axis distance from the far beam surface of the first lens to the far beam surface of the last lens, CT1 is the center thickness of the first lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis.

[0233] |R3 / R4|=0.68, where R3 is the curvature radius of the far beam surface of the second lens, and R4 is the curvature radius of the near beam surface of the second lens.

[0234] |f2 / R4|=1.74, where R4 is the curvature radius of the near optical surface of the second lens, and f2 is the effective focal length of the second lens.

[0235] f / CT2=4.59, where f is the effective focal length of the optical system, and CT2 is the center thickness of the second lens on the optical axis.

[0236] i=1, Vi / 10 / Nmax=4.69; i=2, Vi / 10 / Nmax=4.69; i=3, Vi / 10 / Nmax=4.69; where Vi is the Abbe number of the i-th lens, and Nmax is the lens with the largest refractive index among the first lens, reflective polarizer, quarter-wave plate, second lens, and third lens.

[0237] In Example 6, both the outer and inner side surfaces of any one of the first lens E1 to the third lens E3 are aspherical surfaces. Table 18 shows the high-order coefficients A4, A6, A8, A10, and A12 of the aspherical mirror surfaces S4, S5, S6, S7, and S8 that can be used in Example 6.

[0238] Face number A4 A6 A8 A10 A12 S4 3.2651E+01 -9.7176E-02 9.9064E-02 1.5772E-02 -2.2535E-02 S5 2.6670E+01 -4.7850E+00 -1.5270E+00 5.6876E-01 -4.6452E-02 S6 2.6405E+01 -6.8844E+00 -3.4335E+00 1.1586E+00 -9.8343E-03 S7 2.6317E+01 -1.2087E+01 4.1883E-01 8.2644E-01 2.9312E-01 S8 2.6110E+01 -1.0216E+00 -4.3249E+00 3.7730E+00 -2.9785E-01

[0239] Table 18

[0240] Figure 12a The axial chromatic aberration curve of the visual optical system of Example 6 is shown, which indicates the deviation of the convergence point of light of different wavelengths after passing through the lens. Figure 12b The astigmatism curve of the visual optical system of Example 6 is shown, which indicates the meridional field curvature and the sagittal field curvature. Figure 12c The distortion curve of the visual optical system of Example 6 is shown, which represents the distortion value under different viewing angles. Figures 12a to 12c As shown, the visual optical system provided in Example 6 can achieve good imaging quality. Specific embodiment 7

[0242] Figure 13 This is a schematic diagram of the structure of Example 7 of the visual optical system of the present application. The visual optical system includes: a first element group, a second lens E2, a third lens E3, and a light source. The first element group, the second lens E2, and the third lens E3 are arranged in sequence along the optical axis from the human eye side to the position of the light source S9. The second lens has positive focal power. The first element group includes a first lens E1, a reflective polarizer RP, and a quarter-wave plate QWP. The first lens E1, the reflective polarizer RP, the quarter-wave plate QWP, the second lens E2, and the third lens E3 have a far light surface away from the light source S9 and a near light surface toward the light source. The far light surface of the reflective polarizer RP is at least partially in contact with the near light surface of the first lens E1, and the near light surface of the reflective polarizer RP is at least partially in contact with the far light surface of the quarter-wave plate QWP. In this embodiment of the present application, the reflective polarizer RP and the quarter-wave plate QWP are combined into a single film, which reduces the number of surfaces to be attached during the assembly process and helps improve attachment efficiency. Attached to the near optical surface of the first lens, it participates in the system's optical path folding process.

[0243] Among them, the light source emits a circularly polarized light, which passes through the third lens, the second lens and the quarter-wave plate and becomes linearly polarized light. It is reflected after passing through the reflective polarization element, and then passes through the quarter-wave plate and the second lens. It is reflected by the partial reflective layer on the second lens, and finally passes through the second lens, the quarter-wave plate, the reflective polarization element, and the first lens and enters the human eye, realizing the folding of the light path and thus shortening the total optical length.

[0244] As shown in Table 19, it is a basic parameter table of the visual optical system of Example 7, wherein the units of the curvature radius, thickness, and focal length are all millimeters (mm).

[0245]

[0246]

[0247] Table 19

[0248] As shown in Table 20, in Example 7, the total effective focal length f of the visual optical system is 27.90 mm, and half of the maximum field angle of the visual optical system, semi-fov, is 53.00°.

[0249]

[0250] Table 20

[0251] The visual optical system in Example 7 satisfies:

[0252] f2 / (f×tan(Semi-FOV))=5.16, where f is the effective focal length of the optical system, f2 is the effective focal length of the second lens, and Semi-FOV is half of the maximum field of view of the visual optical system.

[0253] (SAG21+SAG22) / (SAG21-SAG22)=-0.64, where SAG21 is the on-axis distance between the intersection of the second lens's far light surface and the optical axis and the vertex of the effective radius of the second lens's far light surface; and SAG22 is the on-axis distance between the intersection of the second lens's near light surface and the optical axis and the vertex of the effective radius of the second lens' near light surface.

[0254] (SAG31+SAG32) / (SAG31-SAG32)=1.43, where SAG31 is the on-axis distance between the intersection of the third lens' far light surface and the optical axis and the vertex of the effective radius of the third lens' far light surface; SAG32 is the on-axis distance between the intersection of the third lens' near light surface and the optical axis and the vertex of the effective radius of the third lens' near light surface.

[0255] V1 / N1+V3 / N3=94.50, where V1 is the Abbe number of the first lens, N1 is the refractive index of the first lens, V3 is the Abbe number of the third lens, and N3 is the refractive index of the third lens.

[0256] (R5+R6) / f23=3.60, where R5 is the curvature radius of the far beam surface of the third lens, R6 is the curvature radius of the near beam surface of the third lens, and f23 is the combined focal length of the second lens and the third lens.

[0257] FG12 / CT2=4.73, where CT2 is the center thickness of the second lens on the optical axis, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0258] FG12 / (CT1+T12)=10.70, where FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens; CT1 is the center thickness of the first lens on the optical axis; and T12 is the air gap between the first lens and the second lens on the optical axis.

[0259] FG12 / TD=1.29, where TD is the on-axis distance from the far light surface of the first lens to the near light surface of the last lens, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0260] TD / CT1+TD / CT3=27.59, where TD is the on-axis distance from the far beam surface of the first lens to the far beam surface of the last lens, CT1 is the center thickness of the first lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis.

[0261] |R3 / R4|=4.78, where R3 is the curvature radius of the far beam surface of the second lens, and R4 is the curvature radius of the near beam surface of the second lens.

[0262] |f2 / R4|=1.66, where R4 is the curvature radius of the near optical surface of the second lens, and f2 is the effective focal length of the second lens.

[0263] f / CT2=4.14, where f is the effective focal length of the optical system, and CT2 is the center thickness of the second lens on the optical axis.

[0264] i=1, Vi / 10 / Nmax=4.69; i=2, Vi / 10 / Nmax=4.69; i=3, Vi / 10 / Nmax=4.69; where Vi is the Abbe number of the i-th lens, and Nmax is the lens with the largest refractive index among the first lens, reflective polarizer, quarter-wave plate, second lens, and third lens.

[0265] In Example 7, both the outer and inner side surfaces of any one of the first lens E1 to the third lens E3 are aspherical surfaces. Table 21 shows the high-order coefficients A4, A6, A8, A10, and A12 of the aspherical mirror surfaces S4, S5, S6, S7, and S8 that can be used in Example 7.

[0266] Face number A4 A6 A8 A10 A12 A14 S1 3.1774E+01 -8.1760E-01 3.0502E-01 -9.3494E-02 2.1509E-02 1.0358E-05 S5 3.1006E+01 3.9222E-01 2.9142E-03 -7.2416E-02 -6.3797E-03 -2.5606E-07 S6 3.2041E+01 -3.6827E-03 2.9341E-02 -3.7052E-02 2.6859E-03 5.9215E-08 S7 2.7047E+01 -2.7011E+00 1.4694E+00 -3.9962E-01 -7.8395E-04 0.0000E+00 S8 2.8397E+01 -1.6783E+00 -5.4154E-01 1.4832E+00 -7.1158E-01 0.0000E+00

[0267] Table 21

[0268] Figure 14a The axial chromatic aberration curve of the visual optical system of Example 7 is shown, which indicates the deviation of the convergence point of light of different wavelengths after passing through the lens. Figure 14b The astigmatism curve of the visual optical system of Example 7 is shown, which indicates the meridional field curvature and the sagittal field curvature. Figure 14c The distortion curve of the visual optical system of Example 7 is shown, which represents the distortion value under different viewing angles. Figures 14a to 14c As shown, the visual optical system provided in Example 7 can achieve good imaging quality. Specific embodiment 8

[0270] Figure 15 This is a schematic diagram of the structure of Example 8 of the visual optical system of the present application. The visual optical system includes: a first element group, a second lens E2, a third lens E3, and a light source. The first element group, the second lens E2, and the third lens E3 are arranged sequentially along the optical axis from the human eye side to the position of the light source S9. The second lens has positive optical power. The first element group includes a first lens E1, a reflective polarizer RP, and a quarter-wave plate QWP. The first lens E1, the reflective polarizer RP, the quarter-wave plate QWP, the second lens E2, and the third lens E3 have a far light surface away from the light source S9 and a near light surface toward the light source. The far light surface of the reflective polarizer RP is at least partially in contact with the near light surface of the first lens E1, and the near light surface of the reflective polarizer RP is at least partially in contact with the far light surface of the quarter-wave plate QWP. In this embodiment of the present application, the reflective polarizer RP and the quarter-wave plate QWP are combined into a single film, which reduces the number of surfaces to be attached during the assembly process and helps improve attachment efficiency. Attached to the near optical surface of the first lens, it participates in the system's optical path folding process.

[0271] Among them, the light source emits a circularly polarized light, which passes through the third lens, the second lens and the quarter-wave plate and becomes linearly polarized light. It is reflected after passing through the reflective polarization element, and then passes through the quarter-wave plate and the second lens. It is reflected by the partial reflective layer on the second lens, and finally passes through the second lens, the quarter-wave plate, the reflective polarization element, and the first lens and enters the human eye, realizing the folding of the light path and thus shortening the total optical length.

[0272] As shown in Table 22, it is a basic parameter table of the visual optical system of Example 8, wherein the units of the curvature radius, thickness, and focal length are all millimeters (mm).

[0273]

[0274] Table 22

[0275] As shown in Table 23, in Example 8, the total effective focal length f of the visual optical system is 27.89 mm, and half of the maximum field angle of the visual optical system, semi-fov, is 53.00°.

[0276]

[0277] Table 23

[0278] The visual optical system in Example 8 satisfies:

[0279] f2 / (f×tan(Semi-FOV))=5.43, where f is the effective focal length of the optical system, f2 is the effective focal length of the second lens, and Semi-FOV is half of the maximum field of view of the visual optical system.

[0280] (SAG21+SAG22) / (SAG21-SAG22)=-0.70, where SAG21 is the on-axis distance between the intersection of the second lens's far light surface and the optical axis and the vertex of the effective radius of the second lens's far light surface; SAG22 is the on-axis distance between the intersection of the second lens's near light surface and the optical axis and the vertex of the effective radius of the second lens' near light surface.

[0281] (SAG31+SAG32) / (SAG31-SAG32)=2.17, where SAG31 is the on-axis distance between the intersection of the third lens' far light surface and the optical axis and the vertex of the effective radius of the third lens' far light surface; SAG32 is the on-axis distance between the intersection of the third lens' near light surface and the optical axis and the vertex of the effective radius of the third lens' near light surface.

[0282] V1 / N1+V3 / N3=94.50, where V1 is the Abbe number of the first lens, N1 is the refractive index of the first lens, V3 is the Abbe number of the third lens, and N3 is the refractive index of the third lens.

[0283] (R5+R6) / f23=1.66, where R5 is the curvature radius of the far beam surface of the third lens, R6 is the curvature radius of the near beam surface of the third lens, and f23 is the combined focal length of the second lens and the third lens.

[0284] FG12 / CT2=5.96, where CT2 is the center thickness of the second lens on the optical axis, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0285] FG12 / (CT1+T12)=11.47, where FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens; CT1 is the center thickness of the first lens on the optical axis; and T12 is the air gap between the first lens and the second lens on the optical axis.

[0286] FG12 / TD=1.60, where TD is the on-axis distance from the far light surface of the first lens to the near light surface of the last lens, and FG12 is the combined focal length of the first lens, reflective polarizer, quarter-wave plate, and second lens.

[0287] TD / CT1+TD / CT3=21.12, where TD is the on-axis distance from the far beam surface of the first lens to the far beam surface of the last lens, CT1 is the center thickness of the first lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis.

[0288] |R3 / R4|=5.53, where R3 is the curvature radius of the far beam surface of the second lens, and R4 is the curvature radius of the near beam surface of the second lens.

[0289] |f2 / R4|=1.70, where R4 is the curvature radius of the near optical surface of the second lens, and f2 is the effective focal length of the second lens.

[0290] f / CT2=5.13, where f is the effective focal length of the optical system, and CT2 is the center thickness of the second lens on the optical axis.

[0291] i=1, Vi / 10 / Nmax=4.69; i=2, Vi / 10 / Nmax=4.69; i=3, Vi / 10 / Nmax=4.69; where Vi is the Abbe number of the i-th lens, and Nmax is the lens with the largest refractive index among the first lens, reflective polarizer, quarter-wave plate, second lens, and third lens.

[0292] In Example 8, both the outer and inner side surfaces of any one of the first lens E1 to the third lens E3 are aspherical surfaces. Table 24 shows the high-order coefficients A4, A6, A8, A10, and A12 of the aspherical mirror surfaces S4, S5, S6, S7, and S8 that can be used in Example 8.

[0293] Face number A4 A6 A8 A10 A12 S1 3.1541E+01 -5.1643E-02 2.4539E-02 -3.7175E-03 1.5634E-03 S5 2.7326E+01 3.7806E-01 7.6281E-02 -9.9810E-02 -1.2299E-02 S6 2.9845E+01 -5.8125E-02 1.5137E-01 -8.7095E-02 1.0382E-04 S7 2.2869E+01 -1.7395E+00 2.8152E-01 1.0364E-01 2.0176E-02 S8 2.6465E+01 -2.4240E+00 -1.2244E+00 8.8838E-01 1.0974E-01

[0294] Table 24

[0295] Figure 16a The axial chromatic aberration curve of the visual optical system of Example 8 is shown, which indicates the deviation of the convergence point of light of different wavelengths passing through the lens. Figure 16b The astigmatism curve of the visual optical system of Example 8 is shown, which indicates the meridional field curvature and the sagittal field curvature. Figure 16c The distortion curve of the visual optical system of Example 8 is shown, which represents the distortion value under different viewing angles. Figures 16a to 16c As shown, the visual optical system provided in Example 8 can achieve good imaging quality.

[0296] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, improvements, equivalent replacements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A visual optical system, characterized in that: The visual optical system comprises: a first element group, a second lens, a third lens and a light source; Wherein, the first element group, the second lens, and the third lens are arranged in sequence along the optical axis from the human eye side to the light source position; wherein the first element group has positive optical power; The first element group is composed of a reflective polarizing element, a quarter-wave plate and a first lens arranged in sequence from the human eye side to the light source position; Wherein, the first lens, the reflective polarizing element, the quarter-wave plate, the second lens and the third lens have a far light surface away from the light source and a near light surface close to the light source; a first lens having positive optical power, a far optical surface thereof being flat and a near optical surface thereof being convex; a second lens element having positive optical power and a convex far optical surface; a third lens element having optical power, wherein the far optical surface is convex and the near optical surface is concave; Wherein, the near optical surface of the first lens has a partial reflective layer; The combined focal length FG12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens, the center thickness CT1 of the first lens on the optical axis, and the air gap T12 between the first lens and the second lens on the optical axis satisfy the following: 3.34≤FG12 / (CT1+T12)≤7.

82.

2. The visual optical system according to claim 1, wherein: The on-axis distance SAG21 between the intersection of the second lens's far light surface and the optical axis and the vertex of the effective radius of the second lens's far light surface, and the on-axis distance SAG22 between the intersection of the second lens's near light surface and the optical axis and the vertex of the effective radius of the second lens' near light surface, satisfy: 0.65≤(SAG21+SAG22) / (SAG21-SAG22)≤5.

06.

3. The visual optical system according to claim 1, wherein: The on-axis distance SAG31 between the intersection of the far light surface of the third lens and the optical axis and the effective radius vertex of the far light surface of the third lens, and the on-axis distance SAG32 between the intersection of the near light surface of the third lens and the optical axis and the effective radius vertex of the near light surface of the third lens, satisfy: -1.97≤(SAG31+SAG32) / (SAG31-SAG32)≤8.

48.

4. The visual optical system according to claim 1, wherein: The Abbe number V1 of the first lens, the refractive index N1 of the first lens, the Abbe number V3 of the third lens, and the refractive index N3 of the third lens satisfy: 59.76≤V1 / N1+V3 / N3≤94.

50.

5. The visual optical system according to claim 1, wherein: The curvature radius R5 of the far light surface of the third lens, the curvature radius R6 of the near light surface of the third lens, and the combined focal length f23 of the second lens and the third lens satisfy: 0.86≤(R5+R6) / f23≤3.

43.

6. The visual optical system according to claim 1, wherein: The center thickness CT2 of the second lens on the optical axis and the combined focal length FG12 of the first lens, the reflective polarizing element, the quarter-wave plate and the second lens satisfy the following: 2.48≤FG12 / CT2≤5.

55.

7. The visual optical system according to claim 1, wherein: The Abbe number Vi of the i-th lens, and the maximum refractive index Nmax among the first lens, the reflective polarizer, the quarter-wave plate, the second lens, and the third lens, satisfy the following: 3.81≤Vi / 10 / Nmax≤4.69; where i=1, 2, or 3.

8. The visual optical system according to claim 6, wherein: An axial distance TD from the far optical surface of the first lens to the far optical surface of the last lens, and a combined focal length FG12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens satisfy the following conditions: 1.11≤FG12 / TD≤2.

17.

9. The visual optical system according to claim 8, wherein: An axial distance TD between the far light surface of the first lens and the far light surface of the last lens, a center thickness CT1 of the first lens on the optical axis, and a center thickness CT3 of the third lens on the optical axis satisfy the following: 7.22≤TD / CT1+TD / CT3≤17.

32.

10. The visual optical system according to claim 1, wherein: The curvature radius R3 of the far beam surface of the second lens is, and the curvature radius R4 of the near beam surface of the second lens satisfies: 0.23≤|R3 / R4|≤0.

7.

11. The visual optical system according to claim 1, wherein: The curvature radius R4 of the far light surface of the second lens is, and the effective focal length f2 of the second lens satisfies: 0.37≤|f2 / R4|≤2.

79.

12. The visual optical system according to claim 6, wherein: The effective focal length f of the optical system and the center thickness CT2 of the second lens on the optical axis satisfy the following: 2.43≤f / CT2≤5.

30.

13. The visual optical system according to claim 1, wherein: The near optical surface of the quarter wave plate is in at least partial contact with the far optical surface of the first lens.

14. The visual optical system according to claim 1, wherein: The effective focal length f of the optical system, the effective focal length of the second lens is f2 and half of the maximum field of view Semi-FOV of the visual optical system, satisfying: 2.44≤f2 / (f×tan(Semi-FOV))≤3.56.

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