Optical system and VR device including the optical system

Abstract

This application discloses an optical system comprising a first element group and a second element group sequentially from a first side to a second side along the optical axis. The first element group has positive optical power and includes a reflective polarizing element, a first lens, a quarter-wave plate, and a second lens. The second element group has either positive or negative optical power and includes a third lens and a partially reflective element. The effective focal length FG1 of the first element group and the effective focal length FG2 of the second element group satisfy the following condition: 0.5 < (FG2 + FG1) / (FG2 - FG1) < 1.6.

Description

Technical Field

[0001] This application relates to the field of optical components, and more specifically, to an optical system and a VR device including the optical system. Background Technology

[0002] In recent years, with the rapid increase in the number of users in VR device-related fields, people have also put forward higher requirements for the hardware upgrade of VR devices. In particular, the need to improve the portability and visual effects of the devices has become urgent, and the "superficial short-throw optical solution of catadioptric optical system" has become a popular choice.

[0003] Catadioptric optical systems are based on the principle of polarized light. They utilize the selective reflection and projection of different polarized light by reflective polarizers, combined with a quarter-phase delay film to adjust the polarization pattern, achieving a folded optical path effect. This significantly reduces the thickness of the optical module, thereby substantially compressing the size of VR devices. However, current catadioptric optical systems on the market generally employ a two-piece design, which suffers from severe ghosting issues and a limited field of view, thus affecting its optical performance and application range. Therefore, improving current catadioptric optical system designs, such as by adjusting the folded optical path structure, to address the ghosting problem and further increase the field of view is one of the technical problems that those skilled in the art need to solve. Summary of the Invention

[0004] This application provides an optical system that may include a first element group and a second element group sequentially from a first side to a second side along the optical axis. The first element group has positive optical power and includes a reflective polarizing element, a first lens, a quarter-wave plate, and a second lens. The second element group has positive or negative optical power and includes a third lens and a partially reflective element. The effective focal length FG1 of the first element group and the effective focal length FG2 of the second element group can satisfy: 0.5 < (FG2 + FG1) / (FG2 - FG1) < 1.6.

[0005] In one embodiment, the radius of curvature R2 of the second side surface of the first lens and the radius of curvature R1 of the first side surface of the first lens can satisfy: 0.4 <R2 / R1<1.7。

[0006] In one embodiment, the radius of curvature R3 of the first side surface of the second lens and the radius of curvature R4 of the second side surface of the second lens can satisfy: -0.9<(R3-R4) / (R3+R4)<0.7.

[0007] In one embodiment, the refractive index N1 of the first lens, the refractive index N2 of the second lens, the center thickness CTR of the reflective polarizing element on the optical axis, and the center thickness CTQ of the quarter-wave plate on the optical axis can satisfy: 1.2mm < (N1+N2)×(CTR+CTQ) < 1.6mm.

[0008] In one embodiment, the effective focal length f of the optical system and the entrance pupil diameter EPD of the optical system can satisfy: 5.3 <f / EPD<6.0。

[0009] In one embodiment, the effective focal length FG1 of the first element group, the center thickness CT1 of the first lens on the optical axis, and the center thickness CT2 of the second lens on the optical axis can satisfy: 2 <FG1 / (CT1+CT2)<8。

[0010] In one embodiment, the optical system further includes an aperture stop and an image surface disposed on the second side, wherein the distance SL from the aperture stop to the image surface on the optical axis and the distance TD from the first side surface of the first lens to the second side surface of the third lens on the optical axis satisfy: 2.5 <SL / TD<3.3。

[0011] In one embodiment, the optical system further includes an aperture stop, wherein the distance SD from the aperture stop to the second side surface of the third lens on the optical axis and the distance ER from the aperture stop to the first side surface of the first lens on the optical axis satisfy: 1.6 <SD / ER<2.0。

[0012] In one embodiment, the radius of curvature R1 of the first side surface of the first lens, the radius of curvature R3 of the first side surface of the second lens, the Abbe number V1 of the first lens, and the Abbe number V2 of the second lens can satisfy: 2.0mm < |R1+R3| / (V1+V2) < 6.9mm.

[0013] In one embodiment, the center thickness CTQ of the quarter-wave plate on the optical axis, the air gap T23 between the second lens and the third lens on the optical axis, the center thickness CT3 of the third lens on the optical axis, and the Abbe number V3 of the third lens can satisfy: 0.05mm < (CTQ + T23 + CT3) / V3 < 0.35mm.

[0014] In one embodiment, the first side surface of the first lens is concave, and the second side surface is convex.

[0015] In one embodiment, the first side surface of the second lens is concave and the second side surface is convex; and the first side surface of the third lens is concave.

[0016] On the other hand, this application also provides a VR device, which includes an optical system provided by at least one of the above embodiments, wherein the first side is the human eye side and the second side is the display side.

[0017] The optical system disclosed in this application includes a first element group and a second element group sequentially from the first side to the second side along the optical axis. The first element group includes a reflective polarizing element, a first lens, a quarter-wave plate, and a second lens, and the first element group has positive optical power. The second element group includes a third lens and a partially reflective element. By controlling the effective focal length of the first element group and the second element group to satisfy the condition 0.5 < (FG2 + FG1) / (FG2 - FG1) < 1.6, it is beneficial to reduce spherical aberration and chromatic aberration; it is beneficial to increase the field of view and improve ghosting; and it is beneficial to the lightweight design of the system while satisfying the optical power distribution of the system. Attached Figure Description

[0018] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments, taken in conjunction with the accompanying drawings. In the drawings:

[0019] Figure 1 A schematic diagram of the structure of the optical system according to Embodiment 1 of this application is shown;

[0020] Figures 2A to 2C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Example 1 are shown respectively.

[0021] Figure 3 A schematic diagram of the structure of the optical system according to Embodiment 2 of this application is shown;

[0022] Figures 4A to 4C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Example 2 are shown respectively.

[0023] Figure 5 A schematic diagram of the structure of the optical system according to Embodiment 3 of this application is shown;

[0024] Figures 6A to 6C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Example 3 are shown respectively.

[0025] Figure 7 A schematic diagram of the structure of the optical system according to Embodiment 4 of this application is shown;

[0026] Figures 8A to 8C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Example 4 are shown respectively.

[0027] Figure 9 A schematic diagram of the structure of the optical system according to Embodiment 5 of this application is shown;

[0028] Figures 10A to 10C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Example 5 are shown respectively.

[0029] Figure 11 A schematic diagram of the structure of the optical system according to Embodiment 6 of this application is shown; and

[0030] Figures 12A to 12C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Example 6 are shown respectively. Detailed Implementation

[0031] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0032] It should be noted that in this specification, the terms "first," "second," 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 optical lens discussed below may also be referred to as the second optical lens, and the second optical lens may also be referred to as the first optical lens.

[0033] 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.

[0034] In this paper, 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.

[0035] 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.

[0036] 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 a meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formalized sense, unless expressly so specified herein.

[0037] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0038] The features, principles and other aspects of this application are described in detail below.

[0039] An optical system according to an exemplary embodiment of this application may include a first element group and a second element group arranged sequentially along the optical axis from a first side to a second side, wherein the first element group may include a reflective polarizing element, a first lens, a quarter-wave plate and a second lens, and the second element group may include a third lens and a partially reflective element.

[0040] In an exemplary embodiment, the first element group may have positive optical power. The second element group may have positive or negative optical power.

[0041] In an exemplary embodiment, the first side may be, for example, the human eye side, and the second side may be, for example, the display side. The optical system may be used in various VR display devices.

[0042] In an exemplary embodiment, the first side surface of the first lens can be the surface of the first lens closest to the human eye, and the second side surface of the first lens can be the surface of the first lens closest to the display. The first side surface of the second lens can be the surface of the second lens closest to the human eye, and the second side surface of the second lens can be the surface of the second lens closest to the display. The first side surface of the third lens can be the surface of the third lens closest to the human eye, and the second side surface of the third lens can be the surface of the third lens closest to the display.

[0043] The following will refer to Figure 1 An exemplary description of the optical system is provided. For example... Figure 1 As shown, an optical system according to an exemplary embodiment of this application may include a reflective polarizing element RP, a first lens E1, a second lens E2, a quarter-wave plate QWP, a partially reflective element BS, and a third lens E3 arranged sequentially from a first side to a second side. The reflective polarizing element RP, the first lens E1, the second lens E2, and the quarter-wave plate QWP constitute a first element group, and the partially reflective element BS and the third lens E3 constitute a second element group. In practical use, the optical system according to an exemplary embodiment of this application can be used as a VR lens, where the first side corresponds to the human eye side, and the second side corresponds to the display side. The optical system may also include an image plane IMG located on the display side. A light beam emitted from the image plane IMG passes sequentially through the third lens E3 and the partial reflective element BS of the second element group, and the quarter-wave plate QWP, the second lens E2, and the first lens E1 of the first element group, reaching the reflective polarizing element RP. At the reflective polarizing element RP, the beam is reflected and passes again through the first lens E1, the second lens E2, and the quarter-wave plate QWP to reach the partial reflective element BS. Then, the beam is reflected again at the partial reflective element BS and passes sequentially through the quarter-wave plate QWP, the second lens E2, the first lens E1, and the reflective polarizing element RP before exiting towards the viewer's eye. In an exemplary embodiment, the partial reflective element BS may be a semi-transparent, semi-reflective film layer coated on the first side of the third lens E3. In an exemplary embodiment, the reflective polarizing element RP may be attached to the first side of the first lens E1. In an exemplary embodiment, the quarter-wave plate QWP may be attached to the second side of the second lens E2.

[0044] In an exemplary embodiment, the optical system of this application can satisfy the condition 0.5 < (FG2 + FG1) / (FG2 - FG1) < 1.6, where FG1 is the effective focal length of the first element group and FG2 is the effective focal length of the second element group.

[0045] An optical system according to an exemplary embodiment of the present application sequentially arranges a first element group and a second element group from the first side to the second side along the optical axis, and includes a total of three lenses. Specifically, the first element group is provided with a reflective polarizing element, a first lens, a quarter-wave plate, and a second lens, and the second element group is provided with a third lens and a partial reflection element; reasonably controlling the surface shapes of the first lens and the third lens can help reduce spherical aberration and chromatic aberration; attaching the reflective polarizing element to the surface of the first lens on the human eye side, reasonably attaching the quarter-wave plate to the surface of the second lens on the human eye side or the display side, and reasonably plating the partial reflection layer on the surface of the third lens on the human eye side or the display side, which is conducive to increasing the viewing angle and improving ghost images; at the same time, controlling the effective focal length of the first element group and the effective focal length of the second element group to satisfy the conditional formula 0.5 < (FG2 + FG1) / (FG2 - FG1) < 1.6 can help with the lightweight design of the system while meeting the optical power distribution of the system.

[0046] In an exemplary embodiment, the optical system of the present application can satisfy the conditional formula 0.4 < R2 / R1 < 1.7, where R2 is the radius of curvature of the second side surface of the first lens, and R1 is the radius of curvature of the first side surface of the first lens. By controlling the ratio of the radius of curvature of the second side surface of the first lens to the radius of curvature of the first side surface of the first lens within this range, the optical power of the first lens can be controlled, and the first lens can have good processing manufacturability.

[0047] In an exemplary embodiment, the optical system of the present application can satisfy the conditional formula -0.9 < (R3 - R4) / (R3 + R4) < 0.7, where R3 is the radius of curvature of the first side surface of the second lens, and R4 is the radius of curvature of the second side surface of the second lens. By controlling the radius of curvature of the first side surface of the second lens and the radius of curvature of the second side surface of the second lens to satisfy -0.9 < (R3 - R4) / (R3 + R4) < 0.7, the optical power of the second lens can be controlled, and the light ray direction can be controlled more optimally, which helps to improve the image quality and relative illumination of the system.

[0048] In an exemplary embodiment, the optical system of the present application can satisfy the conditional formula 1.2 mm < (N1 + N2) × (CTR + CTQ) < 1.6 mm, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, CTR is the central thickness of the reflective polarizing element on the optical axis, and CTQ is the central thickness of the quarter-wave plate on the optical axis. By controlling the refractive index of the first lens, the refractive index of the second lens, the central thickness of the reflective polarizing element on the optical axis, and the central thickness of the quarter-wave plate on the optical axis to satisfy 1.2 mm < (N1 + N2) × (CTR + CTQ) < 1.6 mm, the optical path of the light ray passing through the reflective polarizing element and the quarter-wave plate can be controlled, and the additional system aberration introduced by the two can be reduced.

[0049] In an exemplary embodiment, the optical system of the present application can satisfy the conditional formula 5.3 < f / EPD < 6.0, where f is the effective focal length of the optical system and EPD is the entrance pupil diameter of the optical system. By controlling the ratio of the effective focal length of the optical system to the entrance pupil diameter of the optical system within this range, the system aperture can be controlled, making the system aperture larger, which is beneficial to increasing the light input of the system.

[0050] In an exemplary embodiment, the optical system of the present application can satisfy the conditional formula 2 < FG1 / (CT1 + CT2) < 8, where FG1 is the effective focal length of the first element group, CT1 is the central thickness of the first lens on the optical axis, and CT2 is the central thickness of the second lens on the optical axis. By controlling the effective focal length of the first element group and the central thicknesses of the first and second lenses on the optical axis to satisfy 2 < FG1 / (CT1 + CT2) < 8, it is not only beneficial to the miniaturization of the system but also beneficial to avoiding the risk of ghost images caused by self-reflection of the lens.

[0051] In an exemplary embodiment, the optical system of the present application may further include an aperture and an image plane disposed on the second side, and the optical system of the present application can satisfy the conditional formula 2.5 < SL / TD < 3.3, where SL is the distance from the aperture to the image plane on the optical axis, and TD is the distance from the first side surface of the first lens to the second side surface of the third lens on the optical axis. By controlling the ratio of the distance from the aperture to the image plane on the optical axis to the distance from the first side surface of the first lens to the second side surface of the third lens on the optical axis within this range, the position of the system aperture can be adjusted, which is beneficial to improving the off-axis aberration of the system and can control the overall length of the system, which is beneficial to achieving a light and compact design of the system.

[0052] In an exemplary embodiment, the optical system of the present application may further include an aperture, and the optical system of the present application can satisfy the conditional formula 1.6 < SD / ER < 2.0, where SD is the distance from the aperture to the second side surface of the third lens on the optical axis, and ER is the distance from the aperture to the first side surface of the first lens on the optical axis. By controlling the ratio of the distance from the aperture to the second side surface of the third lens on the optical axis to the distance from the aperture to the first side surface of the first lens on the optical axis within this range, the aperture position of the system can be controlled, which is beneficial to adjusting the exit pupil position of the optical system and controlling the light transmission amount of the system.

[0053] In an exemplary embodiment, the optical system of this application can satisfy the condition 2.0mm < |R1+R3| / (V1+V2) < 6.9mm, where R1 is the radius of curvature of the first side surface of the first lens, R3 is the radius of curvature of the first side surface of the second lens, V1 is the Abbe number of the first lens, and V2 is the Abbe number of the second lens. By controlling the radius of curvature of the first side surface of the first lens, the radius of curvature of the first side surface of the second lens, the Abbe number of the first lens, and the Abbe number of the second lens to satisfy 2.0mm < |R1+R3| / (V1+V2) < 6.9mm, it is beneficial to optimize the light path and further control the system dispersion introduced by the first and second lenses.

[0054] In an exemplary embodiment, the optical system of this application satisfies the condition 0.05mm < (CTQ + T23 + CT3) / V3 < 0.35mm, where CTQ is the center thickness of the quarter-wave plate on the optical axis, T23 is the air gap between the second and third lenses on the optical axis, CT3 is the center thickness of the third lens on the optical axis, and V3 is the Abbe number of the third lens. By controlling the center thickness of the quarter-wave plate on the optical axis, the air gap between the second and third lenses on the optical axis, the center thickness of the third lens on the optical axis, and the Abbe number of the third lens to satisfy 0.05mm < (CTQ + T23 + CT3) / V3 < 0.35mm, the amount of dispersion introduced by the third lens and the quarter-wave plate can be controlled, which is beneficial for optimizing the chromatic aberration of the system.

[0055] In an exemplary embodiment, the first side surface of the first lens can be concave, and the second side surface can be convex. By controlling the surface shape of the first lens, it is beneficial to control the emission angle of light and to improve the field of view.

[0056] In an exemplary embodiment, the first side surface of the second lens can be concave, and the second side surface can be convex. The first side surface of the third lens can be concave. By reasonably controlling the surface shapes of the second and third lenses, the light path can be further optimized, which is beneficial to improving the image quality of the system and constraining the incident angle of edge light rays, which is beneficial to chip matching.

[0057] In an exemplary embodiment, the optical system of this application may include at least one aperture stop. The aperture stop can constrain the optical path and control the light intensity. The aperture stop can be disposed at an appropriate position in the optical system; for example, the aperture stop can be located between the first side (the human eye side) and the first element group.

[0058] In an exemplary embodiment, the optical system may optionally include protective glass for protecting the photosensitive element located on the imaging surface.

[0059] In an exemplary embodiment, the effective focal length f of the optical system may be, for example, in the range of 27.33 mm to 29.05 mm, the effective focal length FG1 of the first element group may be, for example, in the range of 25.58 mm to 29.93 mm, and the effective focal length FG2 of the second element group may be, for example, in the range of -258.94 mm to 1718.66 mm.

[0060] The optical system according to the above-described embodiments of this application comprises three lenses, including a first element group and a second element group arranged sequentially along the optical axis from the first side to the second side. The first element group includes a reflective polarizing element, a first lens, a quarter-wave plate, and a second lens, while the second element group includes a third lens and a partially reflective element. Simultaneously controlling the effective focal length of the first element group and the effective focal length of the second element group to satisfy the condition 0.5 < (FG2 + FG1) / (FG2 - FG1) < 1.6 can help reduce spherical aberration and chromatic aberration; it can also help increase the field of view and improve ghosting; and it can facilitate the lightweight design of the system while satisfying the system's optical power distribution.

[0061] According to some embodiments of this application, by rationally setting parameters such as the radius of curvature, surface shape, refractive index, center thickness, and Abbe number of the lens, as well as the effective focal length and entrance pupil diameter of the optical system, and by rationally setting parameters such as the aperture stop, lens, and distance between the image plane, the lens can have good manufacturability; it can control the light direction more effectively, which helps improve the image quality and relative illumination of the system; it can reduce the additional system aberrations introduced by the components; it can control the amount of system dispersion introduced by the components, which is beneficial to the optimization of system chromatic aberration. It can increase the amount of light entering the system; it is beneficial to the system's lightweight and miniaturization, while also helping to avoid the risk of ghosting caused by lens self-reflection; it also helps to improve the system's off-axis aberration. Furthermore, it helps to improve the system's field of view; and it is beneficial to chip matching, etc.

[0062] Specific embodiments of the optical system applicable to the above-described embodiments are further described below with reference to the accompanying drawings.

[0063] Example 1

[0064] The following is for reference Figures 1 to 2C The optical system according to Embodiment 1 of this application is described. Figure 1 A schematic diagram of the structure of an optical system according to Embodiment 1 of this application is shown.

[0065] like Figure 1As shown, the optical system, along the optical axis from the human eye side to the display side, includes, in sequence: an aperture stop (STO), a reflective polarizing element (RP), a first lens (E1), a second lens (E2), a quarter-wave plate (QWP), a partially reflective element (BS), a third lens (E3), and an image surface (IMG). The reflective polarizing element (RP), the first lens (E1), the second lens (E2), and the quarter-wave plate (QWP) constitute the first element group, while the partially reflective element (BS) and the third lens (E3) constitute the second element group.

[0066] In this embodiment, the first element group has positive optical power, wherein the surface of the first lens E1 near the human eye is concave and the surface near the display is convex; the surface of the second lens E2 near the human eye is concave and the surface near the display is convex. The second element group has positive optical power, wherein the surface of the third lens E3 near the human eye is concave and the surface near the display is convex.

[0067] In this embodiment, the light beam emitted from the image plane IMG passes sequentially through the third lens E3 and the partial reflective element BS of the second element group, and the quarter-wave plate QWP, the second lens E2 and the first lens E1 of the first element group, and reaches the reflective polarizing element RP. It is reflected at the reflective polarizing element RP and passes through the first lens E1, the second lens E2 and the quarter-wave plate QWP again to reach the partial reflective element BS. After that, the light beam is reflected again at the partial reflective element BS and passes through the quarter-wave plate QWP, the second lens E2, the first lens E1 and the reflective polarizing element RP in sequence to exit towards the human eye side.

[0068] In this embodiment, the partial reflective element BS can be a semi-transparent, semi-reflective film layer deposited on the first side (the surface near the human eye) of the third lens E3. The reflective polarizing element RP can be attached to the first side (the surface near the human eye) of the first lens E1. The quarter-wave plate QWP can be attached to the second side (the surface near the display) of the second lens E2.

[0069] Table 1 shows the basic parameters of the optical system of Example 1, where the units for radius of curvature and thickness are millimeters (mm).

[0070]

[0071]

[0072] Table 1

[0073] In Embodiment 1, the surfaces S3 and S4 of the first lens E1 (near the human eye and near the display), S5 and S6 of the second lens E2 (near the human eye and near the display), and S18 and S19 of the third lens E3 (near the human eye and near the display) are all aspherical. The surface shape x of the aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0074]

[0075] Where x is the distance vector from the vertex of the aspherical surface at a height of h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 2 below gives the higher-order coefficients A4, A6, A8, A19 that can be used for the aspherical mirrors S3-S6, S18 and S19 in Example 1. 10 A 12 A 14 A 16 A 18 and A 20 .

[0076] coefficient\surface S3 S4 S5 S6 S18 S19 A4 -2.8936E-01 -1.5113E-01 1.3327E-01 -4.8905E-03 -2.8988E-01 2.6714E-01 A6 1.9843E-01 -2.6197E-01 -2.7377E-01 3.2017E-01 8.8077E-02 -2.4404E-02 A8 -7.2904E-03 3.0361E-02 -4.9264E-03 -1.2643E-01 5.3540E-03 -1.8751E-01 A10 -1.6157E-03 5.3787E-03 -1.1425E-02 2.2082E-02 -7.6645E-03 9.1382E-03 A12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A14 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A16 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A18 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A20 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0077] Table 2

[0078] Figure 2A The on-axis chromatic aberration curve of the optical system of Embodiment 1 is shown, which represents the deviation of light of different wavelengths from the convergence focal point 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 Example 1 are shown, representing the distortion magnitudes corresponding to different field of view angles. According to... Figures 2A to 2C It can be seen that the optical system given in Example 1 can achieve good imaging quality.

[0079] Example 2

[0080] The following is for reference Figures 3 to 4C An optical system according to Embodiment 2 of this application is described. In this embodiment and the following embodiments, for the sake of brevity, descriptions similar to those in Embodiment 1 will be omitted. Figure 3 A schematic diagram of the structure of an optical system according to Embodiment 2 of this application is shown.

[0081] like Figure 3As shown, the optical system, along the optical axis from the human eye side to the display side, includes, in sequence: an aperture stop (STO), a reflective polarizing element (RP), a first lens (E1), a quarter-wave plate (QWP), a second lens (E2), a partial reflective element (BS), a third lens (E3), and an image plane (IMG). The reflective polarizing element (RP), the first lens (E1), the quarter-wave plate (QWP), and the second lens (E2) constitute the first element group, while the partial reflective element (BS) and the third lens (E3) constitute the second element group.

[0082] In this embodiment, the first element group has positive optical power, wherein the surface of the first lens E1 near the human eye is concave and the surface near the display is convex; the surface of the second lens E2 near the human eye is concave and the surface near the display is convex. The second element group has negative optical power, wherein the surface of the third lens E3 near the human eye is concave and the surface near the display is concave.

[0083] In this embodiment, the light beam emitted from the image plane IMG can sequentially pass through the third lens E3 and the partial reflective element BS of the second element group, and the second lens E2, the quarter-wave plate QWP and the first lens E1 of the first element group, to reach the reflective polarizing element RP. It is reflected at the reflective polarizing element RP and passes through the first lens E1, the quarter-wave plate QWP and the second lens E2 again to reach the partial reflective element BS. After that, the light beam is reflected again at the partial reflective element BS and sequentially passes through the second lens E2, the quarter-wave plate QWP, the first lens E1 and the reflective polarizing element RP to exit towards the human eye.

[0084] In this embodiment, the partial reflective element BS can be a semi-transparent, semi-reflective film layer deposited on the first side (the surface near the human eye) of the third lens E3. The reflective polarizing element RP can be attached to the first side (the surface near the human eye) of the first lens E1. The quarter-wave plate QWP can be attached to the first side (the surface near the human eye) of the second lens E2.

[0085] Table 3 shows the basic parameters of the optical system in Embodiment 2, where the units for radius of curvature and thickness are millimeters (mm). In this embodiment, the surfaces S3 and S4 of the first lens E1 (near the human eye), S6 and S7 of the second lens E2 (near the human eye), and S18 and S19 of the third lens E3 (near the human eye and display side) are all aspherical. Table 4 shows the higher-order coefficients A4, A6, A8, and A19 that can be used for each aspherical mirror surface S3, S4, S6, S7, S18, and S19 in Embodiment 2. 10 A 12 A 14 A 16 A 18 and A20 Each aspherical surface shape can be defined by formula (1) given in Example 1 above.

[0086]

[0087]

[0088] Table 3

[0089] coefficient\surface S3 S4 S6 S7 S18 S19 A4 1.9887E-01 -1.9268E-01 2.3843E-01 -5.2062E-02 2.7880E-01 -2.3371E-01 A6 1.4662E-01 -4.2712E-02 -1.4118E-01 2.9558E-01 7.2087E-02 -1.6573E-01 A8 -3.8664E-02 -1.4715E-01 2.1236E-02 9.3743E-02 -2.4548E-02 -7.1272E-02 A10 -6.5591E-03 -3.1046E-03 1.4213E-04 3.0666E-04 -2.9853E-03 7.2500E-03 A12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A14 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A16 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A18 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A20 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0090] Table 4

[0091] Figure 4A The on-axis chromatic aberration curve of the optical system of Embodiment 2 is shown, which represents the deviation of light of different wavelengths from the convergence focal point 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 in Example 2 are shown, representing the distortion magnitudes corresponding to different field of view angles. According to... Figures 4A to 4C It can be seen that the optical system given in Example 2 can achieve good imaging quality.

[0092] Example 3

[0093] The following is for reference Figures 5 to 6C An optical system according to Embodiment 3 of this application is described. Figure 5 A schematic diagram of the structure of an optical system according to Embodiment 3 of this application is shown.

[0094] like Figure 5 As shown, the optical system, along the optical axis from the human eye side to the display side, includes, in sequence: an aperture stop (STO), a reflective polarizing element (RP), a first lens (E1), a quarter-wave plate (QWP), a second lens (E2), a third lens (E3), a partially reflective element (BS), and an image plane (IMG). The reflective polarizing element (RP), the first lens (E1), the quarter-wave plate (QWP), and the second lens (E2) constitute the first element group, while the third lens (E3) and the partially reflective element (BS) constitute the second element group.

[0095] In this embodiment, the first element group has positive optical power, wherein the surface of the first lens E1 near the human eye is concave and the surface near the display is convex; the surface of the second lens E2 near the human eye is concave and the surface near the display is convex. The second element group has negative optical power, wherein the surface of the third lens E3 near the human eye is concave and the surface near the display is convex.

[0096] In this embodiment, the light beam emitted from the image plane IMG can sequentially pass through the partial reflective element BS and the third lens E3 of the second element group, and the second lens E2, the quarter-wave plate QWP and the first lens E1 of the first element group, and reach the reflective polarizing element RP. It is reflected at the reflective polarizing element RP and passes through the first lens E1, the quarter-wave plate QWP, the second lens E2 and the third lens E3 again to reach the partial reflective element BS. After that, the light beam is reflected again at the partial reflective element BS and sequentially passes through the third lens E3, the second lens E2, the quarter-wave plate QWP, the first lens E1 and the reflective polarizing element RP to exit towards the human eye side.

[0097] In this embodiment, the partial reflective element BS can be a semi-transparent, semi-reflective film layer deposited on the second side (the surface near the display side) of the third lens E3. The reflective polarizing element RP can be attached to the first side (the surface near the human eye side) of the first lens E1. The quarter-wave plate QWP can be attached to the first side (the surface near the human eye side) of the second lens E2.

[0098] Table 5 shows the basic parameters of the optical system in Example 3, where the units for radius of curvature and thickness are millimeters (mm). In this example, the surfaces S3 and S4 of the first lens E1 (near the human eye), S6 and S7 of the second lens E2 (near the human eye), and S8 and S9 of the third lens E3 (near the human eye and display side) are all aspherical. Table 6 shows the higher-order coefficients A4, A6, A8, and A9 of the aspherical mirrors S3, S4, S6, S7, S8, and S9 that can be used in Example 3. 10 A 12 A 14 A 16 A 18 and A 20 Each aspherical surface shape can be defined by formula (1) given in Example 1 above.

[0099] surface element Surface type radius of curvature thickness Refractive index Abbe number Refraction / Reflection S0 spherical endless endless refraction S1 Stabilizer (STO) spherical endless 18.5927 refraction S2 Reflective polarizing element (RP) aspherical -71.7746 0.2000 1.50 57.00 refraction S3 First lens (E1) aspherical -71.7746 1.9700 1.60 26.13 refraction S4 aspherical -95.9737 0.1000 refraction S5 Quarter-wave plate (QWP) aspherical -140.7247 0.3000 1.50 57.00 refraction S6 Second lens (E2) aspherical -140.7247 11.2197 1.56 46.39 refraction S7 aspherical -40.0554 0.1000 refraction S8 Third lens (E3) aspherical -42.1444 2.0000 1.64 21.46 refraction S9 Partial reflective element (BS) aspherical -56.3156 -2.0000 1.64 21.46 reflection S10 aspherical -42.1444 -0.1000 refraction S11 Second lens (E2) aspherical -40.0554 -11.2197 1.56 46.39 refraction S12 Quarter-wave plate (QWP) aspherical -140.7247 -0.3000 1.50 57.00 refraction S13 aspherical -140.7247 -0.1000 refraction S14 First lens (E1) aspherical -95.9737 -1.9700 1.60 26.13 refraction S15 Reflective polarizing element (RP) aspherical -71.7746 1.9700 1.60 26.13 reflection S16 aspherical -95.9737 0.1000 refraction S17 Quarter-wave plate (QWP) aspherical -140.7247 0.3000 1.50 57.00 refraction S18 Second lens (E2) aspherical -140.7247 11.2197 1.56 46.39 refraction S19 aspherical -40.0554 0.1000 refraction S20 Third lens (E3) aspherical -42.1444 2.0000 1.64 21.46 refraction S21 aspherical -56.3156 5.3777 refraction S22 Image View (IMG) spherical endless 0.0000 refraction

[0100] Table 5

[0101] coefficient\surface S3 S4 S6 S7 S8 S9 A4 -3.9844E-02 -1.5037E-01 2.5695E-01 5.9157E-02 -1.4120E-01 -2.9627E-02 A6 1.1446E-01 -2.1338E-01 1.3168E-02 2.5578E-01 -2.0257E-01 -1.6513E-03 A8 -2.8323E-02 1.3476E-01 7.5666E-02 -9.2370E-02 1.2953E-01 -1.2735E-02 A10 -4.4345E-03 -2.4579E-03 -3.4733E-02 -5.1424E-03 8.8666E-03 1.4788E-02 A12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A14 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A16 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A18 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A20 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0102] Table 6

[0103] Figure 6A The on-axis chromatic aberration curve of the optical system of Embodiment 3 is shown, which represents the deviation of light of different wavelengths from the convergence focal point 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 6CThe distortion curves of the optical system in Example 3 are shown, representing the distortion magnitudes corresponding to different field of view angles. According to... Figures 6A to 6C It can be seen that the optical system given in Example 3 can achieve good imaging quality.

[0104] Example 4

[0105] The following is for reference Figures 7 to 8C An optical system according to Embodiment 4 of this application is described. Figure 7 A schematic diagram of the structure of an optical system according to Embodiment 4 of this application is shown.

[0106] like Figure 7 As shown, the optical system, along the optical axis from the human eye side to the display side, includes, in sequence: an aperture stop (STO), a reflective polarizing element (RP), a first lens (E1), a quarter-wave plate (QWP), a second lens (E2), a third lens (E3), a partially reflective element (BS), and an image plane (IMG). The reflective polarizing element (RP), the first lens (E1), the quarter-wave plate (QWP), and the second lens (E2) constitute the first element group, while the third lens (E3) and the partially reflective element (BS) constitute the second element group.

[0107] In this embodiment, the first element group has positive optical power, wherein the surface of the first lens E1 near the human eye is concave and the surface near the display is convex; the surface of the second lens E2 near the human eye is concave and the surface near the display is convex. The second element group has positive optical power, wherein the surface of the third lens E3 near the human eye is concave and the surface near the display is convex.

[0108] In this embodiment, the light beam emitted from the image plane IMG can sequentially pass through the partial reflective element BS and the third lens E3 of the second element group, and the second lens E2, the quarter-wave plate QWP and the first lens E1 of the first element group, and reach the reflective polarizing element RP. It is reflected at the reflective polarizing element RP and passes through the first lens E1, the quarter-wave plate QWP, the second lens E2 and the third lens E3 again to reach the partial reflective element BS. After that, the light beam is reflected again at the partial reflective element BS and sequentially passes through the third lens E3, the second lens E2, the quarter-wave plate QWP, the first lens E1 and the reflective polarizing element RP to exit towards the human eye side.

[0109] In this embodiment, the partial reflective element BS can be a semi-transparent, semi-reflective film layer deposited on the second side (the surface near the display side) of the third lens E3. The reflective polarizing element RP can be attached to the first side (the surface near the human eye side) of the first lens E1. The quarter-wave plate QWP can be attached to the first side (the surface near the human eye side) of the second lens E2.

[0110] Table 7 shows the basic parameters of the optical system in Example 4, where the units for radius of curvature and thickness are millimeters (mm). In this example, the surfaces S3 and S4 of the first lens E1 (near the human eye), S6 and S7 of the second lens E2 (near the human eye), and S8 and S9 of the third lens E3 (near the human eye and display side) are all aspherical. Table 8 shows the higher-order coefficients A4, A6, A8, and A9 of the aspherical mirrors S3, S4, S6, S7, S8, and S9 that can be used in Example 4. 10 A 12 A 14 A 16 A 18 and A 20 Each aspherical surface shape can be defined by formula (1) given in Example 1 above.

[0111]

[0112]

[0113] Table 7

[0114] coefficient\surface S3 S4 S6 S7 S8 S9 A4 -8.4010E-02 -7.8546E-02 1.9036E-01 -2.1572E-02 5.2745E-02 -1.3152E-01 A6 2.2228E-01 1.1684E-02 1.6292E-01 2.4958E-01 -2.4073E-01 1.4465E-01 A8 -2.7025E-02 -4.2279E-02 1.1215E-01 3.7177E-02 5.8821E-02 -2.5503E-02 A10 -2.2199E-03 8.6666E-02 6.9469E-02 5.8298E-02 8.0173E-02 -2.5179E-03 A12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A14 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A16 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A18 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A20 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0115] Table 8

[0116] Figure 8A The on-axis chromatic aberration curve of the optical system of Embodiment 4 is shown, which represents the deviation of light of different wavelengths from the convergence focal point 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 distortion magnitudes corresponding to different field of view angles. According to... Figures 8A to 8C It can be seen that the optical system given in Example 4 can achieve good imaging quality.

[0117] Example 5

[0118] The following is for reference Figures 9 to 10C An optical system according to Embodiment 5 of this application is described. Figure 9 A schematic diagram of the structure of an optical system according to Embodiment 5 of this application is shown.

[0119] like Figure 9As shown, the optical system, along the optical axis from the human eye side to the display side, includes, in sequence: an aperture stop (STO), a reflective polarizing element (RP), a first lens (E1), a quarter-wave plate (QWP), a second lens (E2), a third lens (E3), a partially reflective element (BS), and an image plane (IMG). The reflective polarizing element (RP), the first lens (E1), the quarter-wave plate (QWP), and the second lens (E2) constitute the first element group, while the third lens (E3) and the partially reflective element (BS) constitute the second element group.

[0120] In this embodiment, the first element group has positive optical power, wherein the surface of the first lens E1 near the human eye is concave and the surface near the display is convex; the surface of the second lens E2 near the human eye is concave and the surface near the display is convex. The second element group has negative optical power, wherein the surface of the third lens E3 near the human eye is concave and the surface near the display is convex.

[0121] In this embodiment, the light beam emitted from the image plane IMG can sequentially pass through the partial reflective element BS and the third lens E3 of the second element group, and the second lens E2, the quarter-wave plate QWP and the first lens E1 of the first element group, and reach the reflective polarizing element RP. It is reflected at the reflective polarizing element RP and passes through the first lens E1, the quarter-wave plate QWP, the second lens E2 and the third lens E3 again to reach the partial reflective element BS. After that, the light beam is reflected again at the partial reflective element BS and sequentially passes through the third lens E3, the second lens E2, the quarter-wave plate QWP, the first lens E1 and the reflective polarizing element RP to exit towards the human eye side.

[0122] In this embodiment, the partial reflective element BS can be a semi-transparent, semi-reflective film layer deposited on the second side (the surface near the display side) of the third lens E3. The reflective polarizing element RP can be attached to the first side (the surface near the human eye side) of the first lens E1. The quarter-wave plate QWP can be attached to the first side (the surface near the human eye side) of the second lens E2.

[0123] Table 9 shows the basic parameters of the optical system in Embodiment 5, where the units for radius of curvature and thickness are millimeters (mm). In this embodiment, the surfaces S3 and S4 of the first lens E1 (near the human eye), S6 and S7 of the second lens E2 (near the human eye), and S8 and S9 of the third lens E3 (near the human eye and display side) are all aspherical. Table 10 shows the higher-order coefficients A4, A6, A8, and A9 of the aspherical mirrors S3, S4, S6, S7, S8, and S9 that can be used in Embodiment 5. 10 A 12 A 14 A 16 A18 and A 20 Each aspherical surface shape can be defined by formula (1) given in Example 1 above.

[0124] surface element Surface type radius of curvature thickness Refractive index Abbe number Refraction / Reflection S0 spherical endless endless refraction S1 Stabilizer (STO) spherical endless 18.5927 refraction S2 Reflective polarizing element (RP) aspherical -71.7746 0.2000 1.60 26.13 refraction S3 First lens (E1) aspherical -71.7746 1.9700 1.60 26.13 refraction S4 aspherical -95.9737 0.1000 refraction S5 Quarter-wave plate (QWP) aspherical -140.7247 0.2000 1.50 57.00 refraction S6 Second lens (E2) aspherical -140.7247 11.3197 1.56 46.39 refraction S7 aspherical -40.0554 0.1000 refraction S8 Third lens (E3) aspherical -42.1444 2.0000 1.64 21.46 refraction S9 Partial reflective element (BS) aspherical -56.3156 -2.0000 1.64 21.46 reflection S10 aspherical -42.1444 -0.1000 refraction S11 Second lens (E2) aspherical -40.0554 -11.3197 1.56 46.39 refraction S12 Quarter-wave plate (QWP) aspherical -140.7247 -0.2000 1.50 57.00 refraction S13 aspherical -140.7247 -0.1000 refraction S14 First lens (E1) aspherical -95.9737 -1.9700 1.60 26.13 refraction S15 Reflective polarizing element (RP) aspherical -71.7746 1.9700 1.60 26.13 reflection S16 aspherical -95.9737 0.1000 refraction S17 Quarter-wave plate (QWP) aspherical -140.7247 0.2000 1.50 57.00 refraction S18 Second lens (E2) aspherical -140.7247 11.3197 1.56 46.39 refraction S19 aspherical -40.0554 0.1000 refraction S20 Third lens (E3) aspherical -42.1444 2.0000 1.64 21.46 refraction S21 aspherical -56.3156 5.3828 refraction S22 Image View (IMG) spherical endless 0.0000 refraction

[0125] Table 9

[0126] coefficient\surface S3 S4 S6 S7 S8 S9 A4 -3.9844E-02 -1.5037E-01 2.5695E-01 5.9157E-02 -1.4120E-01 -2.9627E-02 A6 1.1446E-01 -2.1338E-01 1.3168E-02 2.5578E-01 -2.0257E-01 -1.6513E-03 A8 -2.8323E-02 1.3476E-01 7.5666E-02 -9.2370E-02 1.2953E-01 -1.2735E-02 A10 -4.4345E-03 -2.4579E-03 -3.4733E-02 -5.1424E-03 8.8666E-03 1.4788E-02 A12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A14 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A16 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A18 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A20 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0127] Table 10

[0128] Figure 10A The on-axis chromatic aberration curve of the optical system of Embodiment 5 is shown, which represents the deviation of light of different wavelengths from the convergence focal point 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 distortion magnitudes corresponding to different field of view angles. According to... Figures 10A to 10C It can be seen that the optical system given in Example 5 can achieve good imaging quality.

[0129] Example 6

[0130] The following is for reference Figures 11 to 12C An optical system according to Embodiment 6 of this application is described. Figure 11 A schematic diagram of the structure of an optical system according to Embodiment 6 of this application is shown.

[0131] like Figure 11 As shown, the optical system, along the optical axis from the human eye side to the display side, includes, in sequence: an aperture stop (STO), a reflective polarizing element (RP), a first lens (E1), a second lens (E2), a quarter-wave plate (QWP), a third lens (E3), a partially reflective element (BS), and an image surface (IMG). The reflective polarizing element (RP), the first lens (E1), the second lens (E2), and the quarter-wave plate (QWP) constitute the first element group, while the third lens (E3) and the partially reflective element (BS) constitute the second element group.

[0132] In this embodiment, the first element group has positive optical power, wherein the surface of the first lens E1 near the human eye is concave and the surface near the display is convex; the surface of the second lens E2 near the human eye is concave and the surface near the display is convex. The second element group has positive optical power, wherein the surface of the third lens E3 near the human eye is concave and the surface near the display is convex.

[0133] In this embodiment, the light beam emitted from the image plane IMG passes sequentially through the partial reflective element BS and the third lens E3 of the second element group, and the quarter-wave plate QWP, the second lens E2 and the first lens E1 of the first element group, and reaches the reflective polarizing element RP. It is reflected at the reflective polarizing element RP and passes through the first lens E1, the second lens E2, the quarter-wave plate QWP and the third lens E3 again to reach the partial reflective element BS. After that, the light beam is reflected again at the partial reflective element BS and passes sequentially through the third lens E3, the quarter-wave plate QWP, the second lens E2, the first lens E1 and the reflective polarizing element RP to exit towards the human eye.

[0134] In this embodiment, the partial reflective element BS can be a semi-transparent, semi-reflective film layer deposited on the second side (the surface near the display side) of the third lens E3. The reflective polarizing element RP can be attached to the first side (the surface near the human eye side) of the first lens E1. The quarter-wave plate QWP can be attached to the second side (the surface near the display side) of the second lens E2.

[0135] Table 11 shows the basic parameters of the optical system of Embodiment 6, where the units for radius of curvature and thickness are millimeters (mm). In this embodiment, the surfaces S3 and S4 of the first lens E1 (near the human eye), S5 and S6 of the second lens E2 (near the human eye), and S8 and S9 of the third lens E3 (near the human eye and display side) are all aspherical. Table 12 shows the higher-order coefficients A4, A6, A8, and A9 that can be used for each aspherical mirror surface S3-S6, S8, and S9 in Embodiment 6. 10 A 12 A 14 A 16 A 18 and A 20 Each aspherical surface shape can be defined by formula (1) given in Example 1 above.

[0136]

[0137]

[0138] Table 11

[0139] coefficient\surface S3 S4 S5 S6 S8 S9 A4 1.0585E-01 -2.5138E-02 -1.5441E-01 -8.0549E-03 2.4021E-01 6.2176E-02 A6 1.6102E-01 -2.9134E-01 6.4997E-03 2.1074E-01 -1.0945E-01 9.0487E-02 A8 -1.1245E-02 -3.0654E-02 1.0340E-01 1.0632E-01 -4.7500E-02 -1.5944E-03 A10 -8.2352E-03 -6.0035E-03 6.4735E-02 4.0456E-02 -1.5822E-02 4.0798E-03 A12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A14 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A16 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A18 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A20 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0140] Table 12

[0141] Figure 12A The on-axis chromatic aberration curve of the optical system of Embodiment 6 is shown, which represents the deviation of light of different wavelengths from the convergence focal point after passing through the lens. Figure 12BThe astigmatism curves of the optical system of Embodiment 6 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 12C The distortion curves of the optical system in Example 6 are shown, representing the distortion magnitudes corresponding to different field of view angles. According to... Figures 12A to 12C It can be seen that the optical system given in Example 6 can achieve good imaging quality.

[0142] Furthermore, in Examples 1 to 6, the effective focal length FG1 of the first element group, the effective focal length FG2 of the second element group, the effective focal length f of the optical system, the entrance pupil diameter EPD of the optical system, the distance SL from the aperture stop to the image surface of the optical system on the optical axis, the distance SD from the aperture stop to the surface of the third lens near the display side on the optical axis, the distance TD from the surface of the first lens near the human eye side to the surface of the third lens near the display side on the optical axis, the distance ER from the aperture stop to the surface of the first lens near the human eye side on the optical axis, the center thickness CTR of the reflective polarizing element on the optical axis, and the center thickness CTQ of the quarter-wave plate on the optical axis are shown in Table 13.

[0143] Parameters / Examples 1 2 3 4 5 6 FG1(mm) 26.83 25.58 27.34 27.92 27.34 29.93 FG2(mm) 1186.53 -98.95 -258.94 1718.66 -258.94 131.04 f(mm) 27.33 29.05 28.43 28.44 28.43 28.40 EPD (mm) 5.00 5.00 5.00 5.00 5.00 5.00 SL(mm) 38.91 41.81 39.86 40.62 39.87 40.34 SD (mm) 35.71 29.26 34.48 32.70 34.48 32.88 TD(mm) 15.31 12.71 15.69 14.27 15.69 14.81 ER(mm) 20.40 16.55 18.79 18.43 18.79 18.07 CTR(mm) 0.20 0.20 0.20 0.20 0.20 0.20 CTQ(mm) 0.20 0.20 0.30 0.20 0.20 0.20

[0144] Examples 1 to 6 respectively satisfy the conditions shown in Table 14.

[0145]

[0146]

[0147] Table 14

[0148] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of protection involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the concept of this application. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An optical system, characterized in that, Along the optical axis, from the first side to the second side, there are sequentially a first element group and a second element group, wherein, The first element group has positive optical power and includes a reflective polarizing element, a first lens, a quarter-wave plate, and a second lens; the first side of the first lens is concave and the second side is convex; the first side of the second lens is concave and the second side is convex. The second element group has positive or negative optical power, including a third lens and a partial reflective element; the first side of the third lens is concave. The quarter-wave plate is attached to the first or second side of the second lens; The partial reflective element is attached to the first or second side of the third lens; The first side is the human eye side, and the second side is the display side; The optical system contains one reflective polarizing element, one-quarter wave plate, and one partially reflective element. The optical system has three lenses with optical power; and The effective focal length FG1 of the first element group and the effective focal length FG2 of the second element group satisfy the following: 0.59≤(FG2+FG1) / (FG2-FG1)<1.

6.

2. The optical system according to claim 1, characterized in that, The radius of curvature R2 of the second side surface of the first lens satisfies the same condition as the radius of curvature R1 of the first side surface of the first lens: 0.45≤R2 / R1<1.

7.

3. The optical system according to claim 1, characterized in that, The radius of curvature R3 of the first side surface of the second lens and the radius of curvature R4 of the second side surface of the second lens satisfy the following: -0.85≤(R3-R4) / (R3+R4)≤0.

65.

4. The 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 center thickness CTR of the reflective polarizing element on the optical axis, and the center thickness CTQ of the quarter-wave plate on the optical axis satisfy the following: 1.2mm<(N1+N2)×(CTR+CTQ)<1.6mm.

5. The optical system according to claim 1, characterized in that, The effective focal length f of the optical system and the entrance pupil diameter EPD of the optical system satisfy the following: 5.47≤f / EPD≤5.

81.

6. The optical system according to claim 1, characterized in that, The effective focal length FG1 of the first element group, the center thickness CT1 of the first lens on the optical axis, and the center thickness CT2 of the second lens on the optical axis satisfy the following: 2.06≤FG1 / (CT1+CT2)≤7.

94.

7. The optical system according to any one of claims 1 to 6, characterized in that, The optical system further includes an aperture stop and an image surface disposed on the second side, wherein the distance SL from the aperture stop to the image surface on the optical axis and the distance TD from the first side surface of the first lens to the second side surface of the third lens on the optical axis satisfy the following: 2.5 <SL / TD<3.3。 8. The optical system according to any one of claims 1 to 6, characterized in that, The optical system further includes an aperture stop, and the distance SD from the aperture stop to the second side surface of the third lens on the optical axis and the distance ER from the aperture stop to the first side surface of the first lens on the optical axis satisfy the following: 1.75≤SD / ER≤1.

83.

9. The optical system according to any one of claims 1 to 6, characterized in that, The radius of curvature R1 of the first side surface of the first lens, the radius of curvature R3 of the first side surface of the second lens, the Abbe number V1 of the first lens, and the Abbe number V2 of the second lens satisfy the following: 2.0mm<|R1+R3| / (V1+V2)≤6.82mm.

10. The optical system according to any one of claims 1 to 6, characterized in that, The center thickness CTQ of the quarter-wave plate on the optical axis, the air gap T23 between the second and third lenses on the optical axis, the center thickness CT3 of the third lens on the optical axis, and the Abbe number V3 of the third lens satisfy the following: 0.05mm<(CTQ+T23+CT3) / V3<0.35mm.

11. A VR device comprising the optical system as described in any one of claims 1 to 10.

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