Visual optical system

Abstract

This application discloses a visual optical system, comprising: a first lens, a second lens, a reflective polarizing element, a quarter-wave plate, a third lens, and a display; wherein the first lens to the third lens are arranged sequentially along the optical axis from the human eye side to the display position; the reflective polarizing element and the quarter-wave plate are placed between the second lens and the third lens; the first lens, the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens each have at least one far-light surface away from the display and one near-light surface close to the display; the near-light surface of the third lens has a partially reflective layer. Light first passes through the quarter-wave plate, where circularly polarized light becomes linearly polarized light. Upon passing through the reflective polarizing element, it is reflected again, becoming circularly polarized light once more. After being reflected by the partially reflective layer, the circularly polarized light is reversed and passes through the quarter-wave plate again, becoming orthogonally linearly polarized light, which can then pass through the reflective polarizing element, thus projecting an object on the display onto the human eye.

Description

Technical Field

[0001] This application belongs to the field of optical imaging, and in particular relates to a visual optical system. Background Technology

[0002] In recent years, visual optical systems have developed rapidly, especially folded optical path structures, which have attracted widespread attention in the industry. Folded optical path structures utilize the polarization characteristics of light, combining quarter-wave plates and reflective polarizers to fold and compress the optical path, thereby achieving the goal of thinning visual optical systems.

[0003] In folded optical path structures, the materials used for optical path folding require high stress to ensure the polarization characteristics of light. At the same time, achieving a thinner and lighter visual optical system has always been a design goal for major visual optical system manufacturers. Thinning and lightness means that there are many restrictions on the length of the lens system, resulting in greater restrictions on lens parameters and compressing the design freedom of the lens system. How to maximize the design freedom of the lens within a limited size to facilitate subsequent optimization of image quality and adaptation of image algorithms is the problem that this application aims to solve. Summary of the Invention

[0004] This application aims to provide a visual optical system that improves imaging quality by reversing the light path, ultimately projecting objects on a display onto the human eye, immersing the user in a virtual world, while simultaneously meeting the product requirement of a lightweight and thin optical system structure.

[0005] This application provides a visual optical system, comprising: a first lens, a second lens, a reflective polarizing element, a quarter-wave plate, a third lens, and a display; the first lens to the third lens are arranged sequentially along the optical axis from the human eye side to the display position; the reflective polarizing element and the quarter-wave plate are positioned between the second lens and the third lens; the first lens, the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens each have at least one far-light surface away from the display and one near-light surface close to the display; the near-light surface of the third lens has a partially reflective layer; wherein the combined focal length FG23 of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens satisfies 0.5 with the effective focal length f of the optical system. <FG23 / f<2.0。

[0006] According to one embodiment of this application, the radius of curvature R4 of the near-light surface of the second lens, 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 FG23 of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens satisfy: -10<(R4+R5+R6) / FG23<-3.

[0007] According to one embodiment of this application, the refractive index N1 of the first lens, the refractive index N2 of the second lens, and the refractive index Nr of the reflective polarizing element satisfy: 2 < (N1 + N2) / Nr < 2.5.

[0008] According to one embodiment of this application, the refractive index N1 of the first lens, the refractive index N2 of the second lens, the refractive index N3 of the third lens, and the refractive index Nq of the quarter-wave plate satisfy: 3 < (N1 + N2 + N3) / Nq < 3.5.

[0009] According to one embodiment of this application, the Abbe number V1 of the first lens, the Abbe number V2 of the second lens, the refractive index N1 of the first lens, and the refractive index N2 of the second lens satisfy: -26 <V1 / N1-V2 / N2<25。

[0010] According to one embodiment of this application, the maximum refractive index Nmax of the first lens, the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, the Abbe number V2 of the second lens, and the Abbe number V3 of the third lens satisfy: 5 < |V2 + V3| / 10Nmax < 8.5.

[0011] According to one embodiment of this application, the center thickness CT1 of the first lens on the optical axis and the center thickness CT3 of the third lens on the optical axis satisfy: 1 <CT3 / CT1<8。

[0012] According to one embodiment of this application, the center thickness CT2 of the second lens on the optical axis, and the air gap T23 between the second lens and the third lens on the optical axis, satisfy the following relative F-number Fno: 3 <CT2 / T23×fno<36。

[0013] According to one embodiment of this application, the radius of curvature R4 of the near-light surface of the second lens, the radius of curvature R5 of the far-light surface of the third lens, and the radius of curvature R6 of the near-light surface of the third lens satisfy: 1.5 < (R4 + R5) / R6 < 3.5.

[0014] According to one embodiment of this application, the on-axis distance SAG21 between the intersection of the far-light surface and the optical axis of the second lens and the vertex of the effective radius of the far-light surface of the second lens, and the on-axis distance SAG22 between the intersection of the near-light surface and the optical axis of the second lens and the vertex of the effective radius of the near-light surface of the second lens, satisfy: -10<(SAG21+SAG22) / (SAG21-SAG22)<3.

[0015] According to one embodiment of this application, the radius of curvature R2 of the near-light surface of the first lens and the radius of curvature R4 of the near-light surface of the second lens satisfy: -3 <R2 / R4<5.5。

[0016] According to one embodiment of this application, the axial distance TD between the far-light surface of the first lens and the near-light surface of the third lens, and the center thickness CT3 of the third lens on the optical axis, satisfy: 1 <TD / CT3<3。

[0017] According to one embodiment of this application, the far-light surface of the reflective polarizing element is at least partially in contact with the near-light surface of the second lens.

[0018] According to one embodiment of this application, 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; the near-light surface of the quarter-wave plate is at least partially in contact with the far-light surface of the third lens.

[0019] According to one embodiment of this application, the near-light surface of the quarter-wave plate is in at least partial contact with the far-light surface of the third lens.

[0020] The beneficial effects of this application are:

[0021] The visual optical system provided in this application includes multiple lenses. Through the reflective polarizing element and quarter-wave plate between the second and third lenses, and the partially reflective layer on the near-light surface of the third lens, the polarization state and propagation direction of light can be changed: light first passes through the quarter-wave plate, circularly polarized light becomes linearly polarized light, the linearly polarized light is reflected when it passes through the reflective polarizing element, the light passes through the quarter-wave plate again and becomes circularly polarized light, and then is reflected by the partially reflective layer. The circularly polarized light is reflected back and passes through the quarter-wave plate again, becoming orthogonally linearly polarized light, which can pass through the reflective polarizing element. By controlling the ratio of the focal length of the combination of the second and third lenses to the effective focal length of the optical system, the ratio of the focal length of the first lens to the effective focal length of the optical system is indirectly controlled, the optical power of the system is reasonably allocated, which is beneficial to the selection of optical system architecture, increases design freedom, improves imaging quality and the adaptability of image algorithms, thereby improving the immersive effect of the visual optical system. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of embodiment 1 of the optical system of this application;

[0024] Figures 2a to 2c These are the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system embodiment 1 of this application, respectively.

[0025] Figure 3 This is a schematic diagram of the structure of embodiment 2 of the optical system of this application;

[0026] Figures 4a to 4c These are the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system embodiment 2 of this application, respectively.

[0027] Figure 5 This is a schematic diagram of the structure of the optical system in Embodiment 3 of this application;

[0028] Figures 6a to 6c These are the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system embodiment 3 of this application, respectively.

[0029] Figure 7 This is a schematic diagram of the structure of embodiment 4 of the optical system of this application;

[0030] Figures 8a to 8c These are the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of embodiment 4 of the optical system of this application, respectively.

[0031] Figure 9 This is a schematic diagram of the structure of embodiment 5 of the optical system of this application;

[0032] Figures 10a to 10c These are the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of embodiment 5 of the optical system of this application, respectively.

[0033] Figure 11 This is a schematic diagram of the structure of embodiment 6 of the optical system of this application;

[0034] Figures 12a to 12c These are the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system embodiment 6 of this application, respectively. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0036] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0037] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0038] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0039] In the description of this application, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region. If the lens surface is concave and the location of the concaveness is not defined, 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-light surface of the lens, and the surface of each lens closest to the imaging plane is called the near-light surface of the lens.

[0040] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formalized manner unless expressly so specified herein.

[0041] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments may be combined with each other. The features, principles and other aspects of this application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] Exemplary Embodiment

[0043] The optical system of the exemplary embodiment of this application includes: a first lens, a second lens, a reflective polarizing element, a quarter-wave plate, a third lens, and a display; wherein, the first lens to the third lens are arranged in sequence along the optical axis from the human eye side to the display position; the reflective polarizing element and the quarter-wave plate are disposed between the second lens and the third lens; the first lens, the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens respectively have at least one far-light surface away from the display and a near-light surface close to the display; the near-light surface of the third lens has a partial reflective layer. In the embodiment of this application, the optical system includes three lenses, a reflective polarizing element, a quarter-wave plate, and a display, forming a visual system that can project the object on the display onto the human eye, enabling people to immerse in the virtual world. Among them, the reflective polarizing element and the quarter-wave plate are disposed between the second lens and the third lens, and the near-light surface of the third lens has a partial reflective layer, which can change the polarization state and the propagation direction of light: the light first passes through the quarter-wave plate, and the circularly polarized light becomes linearly polarized light. When the linearly polarized light passes through the reflective polarizing element, reflection occurs. The light passes through the quarter-wave plate again and becomes circularly polarized light, and then is reflected by the partial reflective layer. After the circularly polarized light is reversed, it passes through the quarter-wave plate again and becomes orthogonally linearly polarized light, which can pass through the reflective polarizing element.

[0044] In the exemplary embodiment of this application, the combined focal length FG23 of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, and the effective focal length f of this optical system satisfy: 0.5 < FG23 / f < 2.0. By controlling the ratio of the combined focal length of the second lens to the third lens to the effective focal length of the optical system, the ratio of the focal length of the first lens to the effective focal length of the optical system is indirectly controlled within a reasonable range, and the optical power of the system is reasonably distributed, which is beneficial to the selection of the optical system architecture. More specifically, the combined focal length FG23 of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, and the effective focal length f of this optical system satisfy: 0.51 < FG23 / f < 1.99

[0045] In this exemplary embodiment, the radius of curvature R4 of the near-light surface of the second lens, 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 FG23 of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens satisfy: -10 < (R4 + R5 + R6) / FG23 < -3. By controlling the ratio of the radius of curvature of the second and third lenses to the combined focal length within a reasonable range, the center thickness of the second and third lenses and the air gap between them are constrained, which is beneficial to the assembly stability of the second and third lenses. More specifically, the radius of curvature R4 of the near-light surface of the second lens, 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 FG23 of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens satisfy: -9.99 < (R4 + R5 + R6) / FG23 < -3.01.

[0046] In this exemplary embodiment, the refractive index N1 of the first lens, the refractive index N2 of the second lens, and the refractive index Nr of the reflective polarizing element satisfy: 2 < (N1 + N2) / Nr < 2.5. By controlling the refractive indices of the first lens, the second lens, and the reflective polarizing element, the refractive index of the polarizing element is made close to the refractive indices of the two lenses, which is beneficial for selecting the thickness of the reflective polarizing element. When the thickness of the reflective polarizing element changes, the performance loss of the optical system can be minimized by changing the lens thickness. More specifically, the refractive index N1 of the first lens, the refractive index N2 of the second lens, and the refractive index Nr of the reflective polarizing element satisfy: 2.01 < (N1 + N2) / Nr < 2.49.

[0047] In this exemplary embodiment, the refractive indices N1 of the first lens, N2 of the second lens, N3 of the third lens, and Nq of the quarter-wave plate satisfy the condition: 3 < (N1 + N2 + N3) / Nq < 3.5. By controlling the refractive indices of the three lenses and the quarter-wave plate, making the refractive index of the quarter-wave plate comparable to that of the lenses, it is beneficial to reduce the performance loss caused by changes in the polarization state of light. More specifically, the refractive indices N1 of the first lens, N2 of the second lens, N3 of the third lens, and Nq of the quarter-wave plate satisfy the condition: 3.01 < (N1 + N2 + N3) / Nq < 3.49.

[0048] In the present exemplary embodiment, the Abbe number V1 of the first lens, the Abbe number V2 of the second lens, the refractive index N1 of the first lens, and the refractive index N2 of the second lens satisfy: -26 < V1 / N1 - V2 / N2 < 25. By controlling the ratio of the Abbe numbers and refractive indices of the first lens and the second lens within a reasonable range, the aberration introduced by the third lens can be corrected, which is beneficial to improving the performance of the optical system. More specifically, the Abbe number V1 of the first lens, the Abbe number V2 of the second lens, the refractive index N1 of the first lens, and the refractive index N2 of the second lens satisfy: -26.01 < V1 / N1 - V2 / N2 < 24.99.

[0049] In the present exemplary embodiment, the maximum refractive index Nmax among the first lens, the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, the Abbe number V2 of the second lens, and the Abbe number V3 of the third lens satisfy: 5 < |V2 + V3| / 10Nmax < 8.5. By controlling the ratio of the Abbe numbers of the second lens and the third lens to the maximum refractive index in the polarizing element and the third lens within a reasonable range, it is beneficial to correct the chromatic aberration of the system. More specifically, the maximum refractive index Nmax among the first lens, the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, the Abbe number V2 of the second lens, and the Abbe number V3 of the third lens satisfy: 5.01 < |V2 + V3| / 10Nmax < 8.49.

[0050] In the present exemplary embodiment, 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: 1 < CT3 / CT1 < 8. By controlling the ratio of the central thicknesses of the third lens and the first lens within a reasonable range, the central thickness of the third lens is made larger, so that the optical path folding length can be increased, which is beneficial to reducing the thickness of the visual optical system device. More specifically, 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: 1.01 < CT3 / CT1 < 7.99.

[0051] In the present exemplary embodiment, the central thickness CT2 of the second lens on the optical axis, the air gap T23 between the second lens and the third lens on the optical axis, and the relative F number Fno satisfy: 3 < CT2 / T23 × fno < 36. By controlling the optical system of the central thickness of the second lens, the subsequent air gap, and the F number, under the condition of a certain system focal length, the aperture of the optical system is restricted, and then the strength of the second lens is restricted, which is beneficial to the molding and assembly stability of the second lens. More specifically, the central thickness CT2 of the second lens on the optical axis, the air gap T23 between the second lens and the third lens on the optical axis, and the relative F number Fno satisfy: 3.01 < CT2 / T23 × fno < 35.99.

[0052] In this exemplary embodiment, the radius of curvature R4 of the near-light surface of the second lens, the radius of curvature R5 of the far-light surface of the third lens, and the radius of curvature R6 of the near-light surface of the third lens satisfy: 1.5 < (R4 + R5) / R6 < 3.5. By controlling the radii of curvature of the near-light surface of the second lens and the two surfaces of the third lens, the shape of the lens is constrained, thereby controlling the incident angle of the light on the lens surface when the light is refracted. On the one hand, the reflection efficiency of the near-light surface of the third lens is increased, and on the other hand, the polarization efficiency of the light passing through the quarter-wave plate and the reflective polarizing element is increased. More specifically, the radius of curvature R4 of the near-light surface of the second lens, the radius of curvature R5 of the far-light surface of the third lens, and the radius of curvature R6 of the near-light surface of the third lens satisfy: 1.51 < (R4 + R5) / R6 < 3.49.

[0053] In this exemplary embodiment, the axial distance SAG21 between the intersection of the far-light surface of the second lens and the optical axis and the vertex of the effective radius of the far-light surface of the second lens, and the axial distance SAG22 between the intersection of the near-light surface of the second lens and the optical axis and the vertex of the effective radius of the near-light surface of the second lens satisfy: -10 < (SAG21 + SAG22) / (SAG21 - SAG22) < 3. By controlling the sag heights of the two surfaces of the second lens, the shapes of the two surfaces of the second lens are controlled, which is beneficial to the molding of the second lens. More specifically, the axial distance SAG21 between the intersection of the far-light surface of the second lens and the optical axis and the vertex of the effective radius of the far-light surface of the second lens, and the axial distance SAG22 between the intersection of the near-light surface of the second lens and the optical axis and the vertex of the effective radius of the near-light surface of the second lens satisfy: -9.99 < (SAG21 + SAG22) / (SAG21 - SAG22) < 2.99.

[0054] In this exemplary embodiment, the radius of curvature R2 of the near-light surface of the first lens and the radius of curvature R4 of the near-light surface of the second lens satisfy: -3 < R2 / R4 < 5.5. By controlling the ratio of the radius of curvature of the near-light surface of the first lens to that of the near-light surface of the second lens within a reasonable range, it is beneficial to control the shapes of the first lens and the second lens, enabling the two lenses to be properly matched, which is beneficial to the assembly stability of the two lenses. More specifically, the radius of curvature R2 of the near-light surface of the first lens and the radius of curvature R4 of the near-light surface of the second lens satisfy: -2.99 < R2 / R4 < 5.49.

[0055] In the present exemplary embodiment, the axial distance TD from the far-light surface of the first lens to the near-light surface of the third lens, and the central thickness CT3 of the third lens on the optical axis satisfy: 1 < TD / CT3 < 3. By controlling the ratio of the axial distance from the first lens to the third lens to the central thickness of the third lens within a reasonable range, the third lens is relatively thick, which is beneficial to increasing the length of the light ray refraction in the third lens, thereby reducing the thickness of the visual optical system device. More specifically, the axial distance TD from the far-light surface of the first lens to the near-light surface of the third lens, and the central thickness CT3 of the third lens on the optical axis satisfy: 1.01 < TD / CT3 < 2.99.

[0056] In the present exemplary embodiment, the far-light surface of the reflective polarizing element is at least partially in contact with the near-light surface of the second lens. In the embodiment of the present application, the reflective polarizing element is attached to the near-light surface of the second lens, so that the light ray only refracts in the third lens and the air gap between the second lens and the third lens, which is beneficial to increasing the light ray refraction length.

[0057] In the present exemplary embodiment, 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; the near-light surface of the quarter-wave plate is at least partially in contact with the far-light surface of the third lens. In the embodiment of the present application, the reflective polarizing element and the quarter-wave plate are combined together, reducing the curved surface film pasting process; the quarter-wave plate is attached to the far-light surface of the third lens, so that the light ray only reflects in the third lens, reducing the image quality loss caused by the assembly tolerance between the second lens and the third lens.

[0058] In the present exemplary embodiment, the near-light surface of the quarter-wave plate is at least partially in contact with the far-light surface of the third lens. In the embodiment of the present application, the near-light surface of the quarter-wave plate is attached to the far-light surface of the third lens, so that the light ray only reflects in the third lens. On the one hand, it reduces the image quality loss caused by the assembly tolerance between the second lens and the third lens; on the other hand, it is beneficial to reducing the ghost image risk caused by the light ray reflection between multiple elements.

[0059] In the present 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 shape x of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0060]

[0061] Where x is the sagitta of the 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.

[0062] In this exemplary embodiment, the optical system may further include an aperture stop. The aperture stop may be positioned as needed, for example, it may be positioned between the object side and the first lens. Optionally, the 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 plane.

[0063] The optical system according to the above embodiments of this application can employ multiple lenses, such as the three lenses described above. By rationally allocating the optical power, surface shape, center thickness of each lens, and on-axis spacing between each lens, the optical system has a large imaging plane, resulting in a wide imaging range and high imaging quality, while ensuring the ultra-thin design of the mobile phone.

[0064] In an exemplary embodiment, at least one of the mirror surfaces of each lens is an aspherical mirror surface; that is, at least one mirror surface from the far-light surface of the first lens to the far-light surface of the third lens is an aspherical mirror surface. The characteristic of an aspherical lens is that its curvature changes continuously from the lens center to the lens periphery. Unlike a spherical lens, which has a constant curvature from the lens center to the lens periphery, an aspherical lens has better curvature radius characteristics, offering advantages in improving distortion aberrations and astigmatism. By using an aspherical lens, aberrations occurring during imaging can be eliminated as much as possible, thereby improving image quality. Optionally, at least one of the far-light surface and near-light surface of each of the first, second, and third lenses is an aspherical mirror surface. Optionally, both the far-light surface and near-light surface of each of the first, second, and third lenses are aspherical mirror surfaces.

[0065] However, those skilled in the art will understand that the number of lenses constituting the optical system can be changed without departing from the technical solutions claimed in this application to obtain the various results and advantages described in this specification. For example, although three lenses are described as an example in the embodiments, the optical system is not limited to including three lenses, and may include other numbers of lenses if necessary.

[0066] Specific embodiments of the optical system applicable to the above embodiments are further described below with reference to the accompanying drawings. Specific Implementation Example 1

[0068] Figure 1 This is a schematic diagram of the structure of the optical system embodiment 1 of this application. The optical system includes: aperture stop STO, first lens E1, second lens E2, reflective polarizing element RP, quarter-wave plate QWP, third lens E3, and display.

[0069] The first lens E1 to the third lens E3 are arranged sequentially along the optical axis from the human eye side to the display position. A reflective polarizing element RP and a quarter-wave plate QWP are arranged between the second lens E2 and the third lens E3. The first lens E1, the second lens E2, the reflective polarizing element RP, the quarter-wave plate QWP, and the third lens E3 each have a far-light surface away from the display and a near-light surface closer to the display. The far-light surface of the third lens E3 has a partial reflective layer.

[0070] Table 1 shows the basic parameters of the optical system in Example 1, where the units for radius of curvature, thickness, and focal length are all millimeters (mm).

[0071]

[0072] Table 1

[0073] As shown in Table 2, in Example 1, the total effective focal length of the optical system is f = 26.63 mm, and the distance TTL from the far-light surface S1 of the first lens E1 to the imaging surface of the optical system on the optical axis is 29.99 mm.

[0074]

[0075] Table 2

[0076] The optical system in Example 1 satisfies:

[0077] FG23 / f = 1.08, where FG23 is the combined focal length of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, and f is the effective focal length of the optical system.

[0078] (R4+R5+R6) / FG23=-3.77, where R4 is the radius of curvature of the near-light surface of the second lens, R5 is the radius of curvature of the far-light surface of the third lens, R6 is the radius of curvature of the near-light surface of the third lens, and FG23 is the combined focal length of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens.

[0079] (N1+N2) / Nr=2.05, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, and Nr is the refractive index of the reflective polarizing element.

[0080] (N1+N2+N3) / Nq=3.08, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, N3 is the refractive index of the third lens, and Nq is the refractive index of the quarter-wave plate.

[0081] V1 / N1-V2 / N2=0.00, where V1 is the Abbe number of the first lens, V2 is the Abbe number of the second lens, N1 is the refractive index of the first lens, and N2 is the refractive index of the second lens.

[0082] |V2+V3| / 10Nmax=7.27, where Nmax is the maximum refractive index among the first lens, the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, V2 is the Abbe number of the second lens, and V3 is the Abbe number of the third lens.

[0083] CT3 / CT1 = 2.82, where 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.

[0084] CT2 / T23×fno=8.15, where CT2 is the center thickness of the second lens on the optical axis, T23 is the air gap between the second and third lenses on the optical axis, and Fno is the relative F number.

[0085] (R4+R5) / R6=1.82, where R4 is the radius of curvature of the near-light surface of the second lens, R5 is the radius of curvature of the far-light surface of the third lens, and R6 is the radius of curvature of the near-light surface of the third lens.

[0086] (SAG21+SAG22) / (SAG21-SAG22)=-9.28, where SAG21 is the on-axis distance between the intersection of the far-light surface and the optical axis of the second lens and the vertex of the effective radius of the far-light surface of the second lens, and SAG22 is the on-axis distance between the intersection of the near-light surface and the optical axis of the second lens and the vertex of the effective radius of the near-light surface of the second lens.

[0087] R2 / R4 = 5.02, where R2 is the radius of curvature of the near-light surface of the first lens, and R4 is the radius of curvature of the near-light surface of the second lens.

[0088] TD / CT3 = 2.69, where TD is the axial distance from the far-light surface of the first lens to the near-light surface of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

[0089] In Example 1, the far-light and near-light surfaces of any one of the lenses, from the first lens E1 to the third lens E3, are aspherical. Table 3 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical mirrors S1, S2, S3, S4, S7, and S8 in Example 1. 10 .

[0090] Face number A4 A6 A8 A10 S1 -6.2068E-02 -5.7943E-02 2.2887E-03 2.6299E-02 S2 -1.0750E-01 -2.9584E-01 3.0540E-02 4.5909E-02 S3 1.1798E-01 2.3214E-01 -5.9860E-02 5.3373E-02 S4 -3.8381E-02 3.4172E-01 -4.6661E-02 1.8129E-02 S7 4.1356E-02 3.2488E-02 2.2439E-01 -7.4613E-02 S8 2.3923E-01 4.9481E-02 8.8259E-03 -6.1318E-03

[0091] Table 3

[0092] Figure 2a The on-axis chromatic aberration curve of the optical system of Embodiment 1 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 2b The astigmatism curves of the optical system of Embodiment 1 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 2c The distortion curves of the optical system of Embodiment 1 are shown, representing the magnitude of distortion under different viewing angles. According to... Figures 2a to 2c As shown, the optical system given in Example 1 can achieve good imaging quality. Specific Implementation Example 2

[0094] Figure 3 This is a schematic diagram of the structure of the optical system embodiment 2 of this application. The optical system includes: aperture stop STO, first lens E1, second lens E2, reflective polarizing element RP, quarter-wave plate QWP, third lens E3, and display.

[0095] The first lens E1 to the third lens E3 are arranged sequentially along the optical axis from the human eye side to the display position. A reflective polarizing element RP and a quarter-wave plate QWP are arranged between the second lens E2 and the third lens E3. The first lens E1, the second lens E2, the reflective polarizing element RP, the quarter-wave plate QWP, and the third lens E3 each have a far-light surface away from the display and a near-light surface closer to the display. The far-light surface of the third lens E3 has a partial reflective layer.

[0096] Table 4 shows the basic parameters of the optical system in Example 2, where the units for radius of curvature, thickness, and focal length are all millimeters (mm).

[0097]

[0098] Table 4

[0099] As shown in Table 5, in Example 2, the total effective focal length of the optical system is f = 28.45 mm, and the distance TTL from the far-light surface S1 of the first lens E1 to the imaging surface of the optical system on the optical axis is 29.99 mm.

[0100]

[0101]

[0102] Table 5

[0103] The optical system in Example 2 satisfies:

[0104] FG23 / f = 1.19, where FG23 is the combined focal length of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, and f is the effective focal length of the optical system.

[0105] (R4+R5+R6) / FG23=-6.17, where R4 is the radius of curvature of the near-light surface of the second lens, R5 is the radius of curvature of the far-light surface of the third lens, R6 is the radius of curvature of the near-light surface of the third lens, and FG23 is the combined focal length of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens.

[0106] (N1+N2) / Nr=2.14, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, and Nr is the refractive index of the reflective polarizing element.

[0107] (N1+N2+N3) / Nq=3.17, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, N3 is the refractive index of the third lens, and Nq is the refractive index of the quarter-wave plate.

[0108] V1 / N1-V2 / N2=24.99, where V1 is the Abbe number of the first lens, V2 is the Abbe number of the second lens, N1 is the refractive index of the first lens, and N2 is the refractive index of the second lens.

[0109] |V2+V3| / 10Nmax=4.49, where Nmax is the maximum refractive index among the first lens, the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, V2 is the Abbe number of the second lens, and V3 is the Abbe number of the third lens.

[0110] CT3 / CT1 = 1.90, where 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.

[0111] CT2 / T23×fno=3.92, where CT2 is the center thickness of the second lens on the optical axis, T23 is the air gap between the second and third lenses on the optical axis, and Fno is the relative F number.

[0112] (R4+R5) / R6=2.78, where R4 is the radius of curvature of the near-light surface of the second lens, R5 is the radius of curvature of the far-light surface of the third lens, and R6 is the radius of curvature of the near-light surface of the third lens.

[0113] (SAG21+SAG22) / (SAG21-SAG22)=5.31, where SAG21 is the on-axis distance between the intersection of the far-light surface and the optical axis of the second lens and the vertex of the effective radius of the far-light surface of the second lens, and SAG22 is the on-axis distance between the intersection of the near-light surface and the optical axis of the second lens and the vertex of the effective radius of the near-light surface of the second lens.

[0114] R2 / R4 = 0.89, where R2 is the radius of curvature of the near-light surface of the first lens, and R4 is the radius of curvature of the near-light surface of the second lens.

[0115] TD / CT3 = 2.13, where TD is the axial distance from the far-light surface of the first lens to the near-light surface of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

[0116] In Example 2, the far-light and near-light surfaces of any one of the lenses, from the first lens E1 to the third lens E3, are aspherical. Table 6 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical mirrors S1, S2, S3, S4, S7, and S8 in Example 2. 10 .

[0117] Face number A4 A6 A8 A10 S1 -2.4103E-01 -2.1493E-01 6.9071E-03 -8.5895E-03 S2 1.3770E-01 -2.2978E-01 -7.4459E-02 1.5565E-02 S3 1.2197E-01 3.1781E-01 -8.1798E-02 2.8712E-04 S4 -3.0442E-02 1.0082E-01 9.1627E-02 -2.2374E-02 S7 2.6607E-01 6.6022E-02 3.5223E-02 4.8705E-02 S8 -7.4565E-02 1.0880E-01 7.9410E-03 -3.7533E-04

[0118] Table 6

[0119] Figure 4a The on-axis chromatic aberration curve of the optical system of Embodiment 2 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 4b The astigmatism curves of the optical system of Embodiment 2 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 4c The distortion curves of the optical system of Example 2 are shown, representing the magnitude of distortion under different viewing angles. According to... Figures 4a to 4c As shown, the optical system given in Example 2 can achieve good imaging quality. Specific Implementation Example 3

[0121] Figure 5 This is a schematic diagram of the structure of the optical system embodiment 3 of this application. The optical system includes: aperture stop STO, first lens E1, second lens E2, reflective polarizing element RP, quarter-wave plate QWP, third lens E3, and display.

[0122] The first lens E1 to the third lens E3 are arranged sequentially along the optical axis from the human eye side to the display position. A reflective polarizing element RP and a quarter-wave plate QWP are arranged between the second lens E2 and the third lens E3. The first lens E1, the second lens E2, the reflective polarizing element RP, the quarter-wave plate QWP, and the third lens E3 each have a far-light surface away from the display and a near-light surface closer to the display. The far-light surface of the third lens E3 has a partial reflective layer.

[0123] Table 7 shows the basic parameters of the optical system in Example 3, where the units for radius of curvature, thickness, and focal length are millimeters (mm).

[0124]

[0125]

[0126] Table 7

[0127] As shown in Table 8, in Example 3, the total effective focal length of the optical system is f = 26.63 mm, and the distance TTL from the far-light surface S1 of the first lens E1 to the imaging surface of the optical system on the optical axis is 29.99 mm.

[0128]

[0129] Table 8

[0130] The optical system in Example 3 satisfies:

[0131] FG23 / f = 1.08, where FG23 is the combined focal length of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, and f is the effective focal length of the optical system.

[0132] (R4+R5+R6) / FG23=-3.77, where R4 is the radius of curvature of the near-light surface of the second lens, R5 is the radius of curvature of the far-light surface of the third lens, R6 is the radius of curvature of the near-light surface of the third lens, and FG23 is the combined focal length of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens.

[0133] (N1+N2) / Nr=2.05, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, and Nr is the refractive index of the reflective polarizing element.

[0134] (N1+N2+N3) / Nq=3.08, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, N3 is the refractive index of the third lens, and Nq is the refractive index of the quarter-wave plate.

[0135] V1 / N1-V2 / N2=0.00, where V1 is the Abbe number of the first lens, V2 is the Abbe number of the second lens, N1 is the refractive index of the first lens, and N2 is the refractive index of the second lens.

[0136] |V2+V3| / 10Nmax=7.27, where Nmax is the maximum refractive index among the first lens, the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, V2 is the Abbe number of the second lens, and V3 is the Abbe number of the third lens.

[0137] CT3 / CT1 = 2.83, where 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.

[0138] CT2 / T23×fno=8.17, where CT2 is the center thickness of the second lens on the optical axis, T23 is the air gap between the second and third lenses on the optical axis, and Fno is the relative F number.

[0139] (R4+R5) / R6=1.82, where R4 is the radius of curvature of the near-light surface of the second lens, R5 is the radius of curvature of the far-light surface of the third lens, and R6 is the radius of curvature of the near-light surface of the third lens.

[0140] (SAG21+SAG22) / (SAG21-SAG22)=-9.31, where SAG21 is the on-axis distance between the intersection of the far-light surface and the optical axis of the second lens and the vertex of the effective radius of the far-light surface of the second lens, and SAG22 is the on-axis distance between the intersection of the near-light surface and the optical axis of the second lens and the vertex of the effective radius of the near-light surface of the second lens.

[0141] R2 / R4 = 5.03, where R2 is the radius of curvature of the near-light surface of the first lens, and R4 is the radius of curvature of the near-light surface of the second lens.

[0142] TD / CT3 = 2.69, where TD is the axial distance from the far-light surface of the first lens to the near-light surface of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

[0143] In Example 3, the far-light and near-light surfaces of any one of the lenses, from the first lens E1 to the third lens E3, are aspherical. Table 9 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical mirrors S1, S2, S3, S4, S7, and S8 in Example 3. 10 .

[0144] Face number A4 A6 A8 A10 S1 -5.8364E-02 -5.8442E-02 2.4239E-03 2.6687E-02 S2 -1.0750E-01 -2.9590E-01 3.0991E-02 4.6645E-02 S3 7.6651E-02 2.4256E-01 -6.2274E-02 5.4120E-02 S4 -5.0433E-02 3.4333E-01 -4.7694E-02 1.8296E-02 S7 3.4344E-02 3.0611E-02 2.2525E-01 -7.5393E-02 S8 2.3321E-01 5.0190E-02 8.5167E-03 -6.1455E-03

[0145] Table 9

[0146] Figure 6a The on-axis chromatic aberration curve of the optical system of Embodiment 3 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 6b The astigmatism curves of the optical system of Embodiment 3 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 6c The distortion curves of the optical system in Example 3 are shown, representing the magnitude of distortion under different viewing angles. According to... Figures 6a to 6c As shown, the optical system given in Example 3 can achieve good imaging quality. Specific Implementation Example 4

[0148] Figure 7This is a schematic diagram of the structure of embodiment 4 of the optical system of this application. The optical system includes: aperture stop STO, first lens E1, second lens E2, reflective polarizing element RP, quarter-wave plate QWP, third lens E3, and display.

[0149] The first lens E1 to the third lens E3 are arranged sequentially along the optical axis from the human eye side to the display position. A reflective polarizing element RP and a quarter-wave plate QWP are arranged between the second lens E2 and the third lens E3. The first lens E1, the second lens E2, the reflective polarizing element RP, the quarter-wave plate QWP, and the third lens E3 each have a far-light surface away from the display and a near-light surface closer to the display. The far-light surface of the third lens E3 has a partial reflective layer.

[0150] Table 10 shows the basic parameters of the optical system in Example 4, where the units for radius of curvature, thickness, and focal length are all millimeters (mm).

[0151]

[0152] Table 10

[0153] As shown in Table 11, in Example 4, the total effective focal length of the optical system is f = 29.87 mm, and the distance TTL from the far-light surface S1 of the first lens E1 to the imaging surface of the optical system on the optical axis is 30.98 mm.

[0154]

[0155] Table 11

[0156] The optical system in Example 4 satisfies:

[0157] FG23 / f = 0.96, where FG23 is the combined focal length of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, and f is the effective focal length of the optical system.

[0158] (R4+R5+R6) / FG23=-7.37, where R4 is the radius of curvature of the near-light surface of the second lens, R5 is the radius of curvature of the far-light surface of the third lens, R6 is the radius of curvature of the near-light surface of the third lens, and FG23 is the combined focal length of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens.

[0159] (N1+N2) / Nr=2.15, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, and Nr is the refractive index of the reflective polarizing element.

[0160] (N1+N2+N3) / Nq=3.15, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, N3 is the refractive index of the third lens, and Nq is the refractive index of the quarter-wave plate.

[0161] V1 / N1-V2 / N2=-23.19, where V1 is the Abbe number of the first lens, V2 is the Abbe number of the second lens, N1 is the refractive index of the first lens, and N2 is the refractive index of the second lens.

[0162] |V2+V3| / 10Nmax=8.01, where Nmax is the maximum refractive index among the first lens, the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, V2 is the Abbe number of the second lens, and V3 is the Abbe number of the third lens.

[0163] CT3 / CT1 = 7.87, where 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.

[0164] CT2 / T23×fno=30.98, where CT2 is the center thickness of the second lens on the optical axis, T23 is the air gap between the second and third lenses on the optical axis, and Fno is the relative F number.

[0165] (R4+R5) / R6=2.61, where R4 is the radius of curvature of the near-light surface of the second lens, R5 is the radius of curvature of the far-light surface of the third lens, and R6 is the radius of curvature of the near-light surface of the third lens.

[0166] (SAG21+SAG22) / (SAG21-SAG22)=-0.44, where SAG21 is the on-axis distance between the intersection of the far-light surface and the optical axis of the second lens and the vertex of the effective radius of the far-light surface of the second lens, and SAG22 is the on-axis distance between the intersection of the near-light surface and the optical axis of the second lens and the vertex of the effective radius of the near-light surface of the second lens.

[0167] R2 / R4 = -2.13, where R2 is the radius of curvature of the near-light surface of the first lens, and R4 is the radius of curvature of the near-light surface of the second lens.

[0168] TD / CT3 = 1.72, where TD is the axial distance from the far-light surface of the first lens to the near-light surface of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

[0169] In Example 4, the far-light and near-light surfaces of any one of the lenses, from the first lens E1 to the third lens E3, are aspherical. Table 12 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical mirrors S1, S2, S3, S4, S7, and S8 in Example 4.10 .

[0170] Face number A4 A6 A8 A10 S1 -6.6537E-02 -1.5579E-01 -1.0627E-01 1.3356E-02 S2 -1.0460E-02 -3.4232E-01 -1.7173E-01 -2.0332E-02 S3 -7.9799E-02 -2.7833E-01 -1.0099E-01 -1.9830E-02 S4 -8.1178E-02 -1.1870E-01 4.2704E-04 2.3704E-02 S7 2.8672E-01 -2.9025E-03 2.8759E-03 -8.1075E-04 S8 1.1272E-01 -9.1425E-04 -3.7528E-03 -8.9808E-05

[0171] Table 12

[0172] Figure 8a The on-axis chromatic aberration curve of the optical system of Embodiment 4 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 8b The astigmatism curves of the optical system of Example 4 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 8c The distortion curves of the optical system in Example 4 are shown, representing the magnitude of distortion under different viewing angles. According to... Figures 8a to 8c As shown, the optical system given in Example 4 can achieve good imaging quality. Specific Implementation Example 5

[0174] Figure 9 This is a schematic diagram of the structure of embodiment 5 of the optical system of this application. The optical system includes: aperture stop STO, first lens E1, second lens E2, reflective polarizing element RP, quarter-wave plate QWP, third lens E3, and display.

[0175] The first lens E1 to the third lens E3 are arranged sequentially along the optical axis from the human eye side to the display position. A reflective polarizing element RP and a quarter-wave plate QWP are arranged between the second lens E2 and the third lens E3. The first lens E1, the second lens E2, the reflective polarizing element RP, the quarter-wave plate QWP, and the third lens E3 each have a far-light surface away from the display and a near-light surface closer to the display. The far-light surface of the third lens E3 has a partial reflective layer.

[0176] Table 13 shows the basic parameters of the optical system in Example 5, where the units for radius of curvature, thickness, and focal length are all millimeters (mm).

[0177]

[0178] Table 13

[0179] As shown in Table 14, in Example 5, the total effective focal length of the optical system is f = 29.87 mm, and the distance TTL from the far-light surface S1 of the first lens E1 to the imaging surface of the optical system on the optical axis is 30.98 mm.

[0180]

[0181]

[0182] Table 14

[0183] The optical system in Example 5 satisfies:

[0184] FG23 / f = 0.85, where FG23 is the combined focal length of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, and f is the effective focal length of the optical system.

[0185] (R4+R5+R6) / FG23=-8.99, where R4 is the radius of curvature of the near-light surface of the second lens, R5 is the radius of curvature of the far-light surface of the third lens, R6 is the radius of curvature of the near-light surface of the third lens, and FG23 is the combined focal length of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens.

[0186] (N1+N2) / Nr=2.19, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, and Nr is the refractive index of the reflective polarizing element.

[0187] (N1+N2+N3) / Nq=3.29, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, N3 is the refractive index of the third lens, and Nq is the refractive index of the quarter-wave plate.

[0188] V1 / N1-V2 / N2=-25.84, where V1 is the Abbe number of the first lens, V2 is the Abbe number of the second lens, N1 is the refractive index of the first lens, and N2 is the refractive index of the second lens.

[0189] |V2+V3| / 10Nmax=7.01, where Nmax is the maximum refractive index among the first lens, the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, V2 is the Abbe number of the second lens, and V3 is the Abbe number of the third lens.

[0190] CT3 / CT1 = 3.80, where 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.

[0191] CT2 / T23×fno=35.58, where CT2 is the center thickness of the second lens on the optical axis, T23 is the air gap between the second and third lenses on the optical axis, and Fno is the relative F number.

[0192] (R4+R5) / R6=3.16, where R4 is the radius of curvature of the near-light surface of the second lens, R5 is the radius of curvature of the far-light surface of the third lens, and R6 is the radius of curvature of the near-light surface of the third lens.

[0193] (SAG21+SAG22) / (SAG21-SAG22)=-0.52, where SAG21 is the on-axis distance between the intersection of the far-light surface and the optical axis of the second lens and the vertex of the effective radius of the far-light surface of the second lens, and SAG22 is the on-axis distance between the intersection of the near-light surface and the optical axis of the second lens and the vertex of the effective radius of the near-light surface of the second lens.

[0194] R2 / R4 = -2.53, where R2 is the radius of curvature of the near-light surface of the first lens, and R4 is the radius of curvature of the near-light surface of the second lens.

[0195] TD / CT3 = 2.21, where TD is the axial distance from the far-light surface of the first lens to the near-light surface of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

[0196] In Example 5, the far-light and near-light surfaces of any one of the lenses, from the first lens E1 to the third lens E3, are aspherical. Table 15 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical mirrors S1, S2, S3, S4, S7, and S8 in Example 5. 10 .

[0197]

[0198]

[0199] Table 15

[0200] Figure 10a The on-axis chromatic aberration curve of the optical system of Embodiment 5 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 10b The astigmatism curves of the optical system of Example 5 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 10c The distortion curves of the optical system in Example 5 are shown, representing the magnitude of distortion under different viewing angles. According to... Figures 10a to 10c As shown, the optical system given in Example 5 can achieve good imaging quality. Specific Implementation Example 6

[0202] Figure 11 This is a schematic diagram of the structure of the optical system embodiment 6 of this application. The optical system includes: aperture stop STO, first lens E1, second lens E2, reflective polarizing element RP, quarter-wave plate QWP, third lens E3, and display.

[0203] The first lens E1 to the third lens E3 are arranged sequentially along the optical axis from the human eye side to the display position. A reflective polarizing element RP and a quarter-wave plate QWP are arranged between the second lens E2 and the third lens E3. The first lens E1, the second lens E2, the reflective polarizing element RP, the quarter-wave plate QWP, and the third lens E3 each have a far-light surface away from the display and a near-light surface closer to the display. The far-light surface of the third lens E3 has a partial reflective layer.

[0204] Table 16 shows the basic parameters of the optical system in Example 6, where the units for radius of curvature, thickness, and focal length are all millimeters (mm).

[0205]

[0206] Table 16

[0207] As shown in Table 17, in Example 6, the total effective focal length of the optical system is f = 29.97 mm, and the distance TTL from the far-light surface S1 of the first lens E1 to the imaging surface of the optical system on the optical axis is 31.00 mm.

[0208]

[0209] Table 17

[0210] The optical system in Example 6 satisfies:

[0211] FG23 / f = 1.56, where FG23 is the combined focal length of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, and f is the effective focal length of the optical system.

[0212] (R4+R5+R6) / FG23=-5.82, where R4 is the radius of curvature of the near-light surface of the second lens, R5 is the radius of curvature of the far-light surface of the third lens, R6 is the radius of curvature of the near-light surface of the third lens, and FG23 is the combined focal length of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens.

[0213] (N1+N2) / Nr=2.22, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, and Nr is the refractive index of the reflective polarizing element.

[0214] (N1+N2+N3) / Nq=3.25, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, N3 is the refractive index of the third lens, and Nq is the refractive index of the quarter-wave plate.

[0215] V1 / N1-V2 / N2=24.83, where V1 is the Abbe number of the first lens, V2 is the Abbe number of the second lens, N1 is the refractive index of the first lens, and N2 is the refractive index of the second lens.

[0216] |V2+V3| / 10Nmax=5.23, where Nmax is the maximum refractive index among the first lens, the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, V2 is the Abbe number of the second lens, and V3 is the Abbe number of the third lens.

[0217] CT3 / CT1 = 1.71, where 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.

[0218] CT2 / T23×fno=7.20, where CT2 is the center thickness of the second lens on the optical axis, T23 is the air gap between the second and third lenses on the optical axis, and Fno is the relative F number.

[0219] (R4+R5) / R6=3.05, where R4 is the radius of curvature of the near-light surface of the second lens, R5 is the radius of curvature of the far-light surface of the third lens, and R6 is the radius of curvature of the near-light surface of the third lens.

[0220] (SAG21+SAG22) / (SAG21-SAG22)=2.59, where SAG21 is the on-axis distance between the intersection of the far-light surface of the second lens and the optical axis and the vertex of the effective radius of the far-light surface of the second lens, and SAG22 is the on-axis distance between the intersection of the near-light surface of the second lens and the optical axis and the vertex of the effective radius of the near-light surface of the second lens.

[0221] R2 / R4 = 0.33, where R2 is the radius of curvature of the near-light surface of the first lens, and R4 is the radius of curvature of the near-light surface of the second lens.

[0222] TD / CT3 = 1.65, where TD is the axial distance from the far-light surface of the first lens to the near-light surface of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

[0223] In Example 6, the far-light and near-light surfaces of any one of the lenses, from the first lens E1 to the third lens E3, are aspherical. Table 18 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical mirrors S1, S2, S3, S4, S7, and S8 in Example 6. 10 .

[0224] Face number A4 A6 A8 A10 S1 -2.4442E-01 -8.2261E-02 7.6604E-03 4.3819E-05 S2 -8.6047E-02 1.7941E-01 -9.1849E-03 -1.4291E-02 S3 4.5472E-01 8.6253E-02 -3.7131E-02 -5.4029E-03 S4 -4.2015E-01 -1.5530E-01 3.6077E-02 -1.0629E-04 S7 3.1915E-02 -1.9514E-02 1.7659E-02 4.9350E-03 S8 4.5520E-02 -1.7004E-03 2.1327E-03 6.8725E-04

[0225] Table 18

[0226] Figure 12a The on-axis chromatic aberration curve of the optical system of Embodiment 6 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 12b The astigmatism curves of the optical system of Embodiment 6 are shown, representing the meridional image plane curvature and the sagittal image plane curvature. Figure 12c The distortion curves of the optical system of Example 6 are shown, representing the magnitude of distortion under different viewing angles. According to... Figures 12a to 12c As shown, the optical system given in Example 6 can achieve good imaging quality.

[0227] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, improvements, or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A visual optical system, characterized in that, The optical system has three lenses, and along the optical axis from the human eye side to the display position, the optical system includes, in sequence: a first lens, a second lens, a reflective polarizing element, a quarter-wave plate, a third lens, and the display. The first lens to the third lens are arranged sequentially along the optical axis from the human eye side to the display position; The reflective polarizing element and the quarter-wave plate are positioned between the second lens and the third lens; The first lens, the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens each have at least one far-light surface away from the display and one near-light surface close to the display. The near-light surface of the third lens has a partial reflective layer; Wherein, the combined focal length FG23 of the second lens, the reflective polarizing element, the quarter-wave plate and the third lens, and the effective focal length f of the optical system satisfy: 0.85≤FG23 / f≤1.

56.

2. The visual optical system according to claim 1, characterized in that, The curvature radius R4 of the near-light surface of the second lens, 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 FG23 of the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens satisfy: -8.99≤(R4+R5+R6) / FG23≤-3.

77.

3. The visual optical system according to claim 1, characterized in that, The refractive index N1 of the first lens, the refractive index N2 of the second lens, and the refractive index Nr of the reflective polarizing element satisfy: 2 < (N1 + N2) / Nr ≤ 2.

22.

4. The visual optical system according to claim 1, characterized in that, The refractive index N1 of the first lens, the refractive index N2 of the second lens, the refractive index N3 of the third lens, and the refractive index Nq of the quarter-wave plate satisfy: 3.08≤(N1+N2+N3) / Nq≤3.

29.

5. The visual optical system according to claim 1, characterized in that, The Abbe number V1 of the first lens, the Abbe number V2 of the second lens, the refractive index N1 of the first lens, and the refractive index N2 of the second lens satisfy: -25.84≤V1 / N1-V2 / N2<25.

6. The visual optical system according to claim 1, characterized in that, The maximum refractive index Nmax of the first lens, the second lens, the reflective polarizing element, the quarter-wave plate, and the third lens, the Abbe number V2 of the second lens, and the Abbe number V3 of the third lens satisfy: 4.49≤|V2+V3| / 10Nmax≤8.

01.

7. The visual optical system according to claim 1, characterized in that, The center thickness CT1 of the first lens on the optical axis and the center thickness CT3 of the third lens on the optical axis satisfy: 1.71≤CT3 / CT1≤7.

87.

8. The visual optical system according to claim 1, characterized in that, The center thickness CT2 of the second lens on the optical axis, the air gap T23 between the second lens and the third lens on the optical axis, and the relative F number Fno satisfy: 3.92≤CT2 / T23×fno≤35.

58.

9. The visual optical system according to claim 1, characterized in that, The curvature radius R4 of the near-light surface of the second lens, the curvature radius R5 of the far-light surface of the third lens, and the curvature radius R6 of the near-light surface of the third lens satisfy: 1.82≤(R4+R5) / R6≤3.

16.

10. The visual optical system according to claim 1, characterized in that, The axial distance SAG21 between the intersection of the far-light surface and the optical axis of the second lens and the vertex of the effective radius of the far-light surface of the second lens, and the axial distance SAG22 between the intersection of the near-light surface and the optical axis of the second lens and the vertex of the effective radius of the near-light surface of the second lens, satisfy: -9.31≤(SAG21+SAG22) / (SAG21-SAG22)≤5.

31.

11. The visual optical system according to claim 1, characterized in that, The radius of curvature R2 of the near-light surface of the first lens and the radius of curvature R4 of the near-light surface of the second lens satisfy: -2.53≤R2 / R4≤5.

03.

12. The visual optical system according to claim 1, characterized in that, The axial distance TD between the far-light surface of the first lens and the near-light surface of the third lens, and the center thickness CT3 of the third lens on the optical axis, satisfy: 1.65≤TD / CT3≤2.

69.

13. The visual optical system according to claim 1, characterized in that, The far-light surface of the reflective polarizing element is in at least partial contact with the near-light surface of the second lens.

14. The visual optical system according to claim 1, characterized in that, The near-light surface of the reflective polarizing element is in at least partial contact with the far-light surface of the quarter-wave plate; the near-light surface of the quarter-wave plate is in at least partial contact with the far-light surface of the third lens.

15. The visual optical system according to claim 1, characterized in that, The near-light surface of the quarter-wave plate is in at least partial contact with the far-light surface of the third lens.

Images