Optical system and VR device including the same

Abstract

This application discloses an optical system comprising, in order from a first side to a second side along an optical axis: a reflective polarizer; a quarter-wave plate; a first optical lens, the second side of which is convex or flat; a partially reflecting element; and a second optical lens having positive or negative optical power and the second side of which is aspherical. The effective focal length f2 of the second optical lens and the effective focal length f of the optical system satisfy 4<|f2 / f|<7.

Description

Technical Field

[0001] The present application relates to the field of optical elements, and more specifically, to an optical system and a VR device including the optical system. Background Art

[0002] With the increasing demand for online work, the requirements for online interaction are becoming increasingly diverse. To achieve this interaction, the development of mixed reality (MR) has attracted widespread attention. In particular, virtual reality (VR), which was developed earlier, has seen widespread application due to its increasingly mature solutions.

[0003] Currently, VR lenses primarily include aspherical, Fresnel, and Pancake lenses. The Pancake solution applies the principle of refraction to compress the lens length, effectively shortening the length of the headset and making it thinner and lighter. However, when using fewer lenses, the Pancake solution suffers from poor image quality at the edges of the field of view, impacting the consumer experience. Summary of the Invention

[0004] The present application provides an optical system comprising, in order from a first side to a second side along an optical axis, a reflective polarizer; a quarter-wave plate; a first optical lens having a convex or flat second side; a partially reflecting element; and a second optical lens having positive or negative optical power and an aspheric second side. Furthermore, the effective focal length f2 of the second optical lens and the effective focal length f of the optical system satisfy 4<|f2 / f|<7.

[0005] In one embodiment, the optical system further comprises an image surface disposed on the second side, and the image height ImgH presented by the image surface and the entrance pupil diameter EPD of the optical system may satisfy: 4 <ImgH / EPD<5。

[0006] In one embodiment, the optical system further comprises an aperture, and a distance SL from the aperture to the image plane of the optical system on the optical axis and a center thickness CT1 of the first optical lens on the optical axis may satisfy: 2.3 <SL / CT1<3.8。

[0007] In one embodiment, the optical system further comprises an aperture, and the distance SD from the aperture to the second side surface of the second optical lens on the optical axis, the air gap T12 between the first optical lens and the second optical lens on the optical axis, and the center thickness CT2 of the second optical lens on the optical axis may satisfy the following conditions: 2.6 <SD / (T12+CT2)<5.2。

[0008] In one embodiment, the distance TD from the first side surface of the first optical lens to the second side surface of the second optical lens on the optical axis and the image height ImgH presented by the image surface of the optical system may satisfy: 0.95 <TD / ImgH<1.45。

[0009] In one embodiment, the effective focal length f of the optical system and the maximum field of view FOV of the optical system can satisfy: 33mm <f×tan(FOV / 2)<37.5mm。

[0010] In one embodiment, the refractive index N2 of the second optical lens, the refractive index N1 of the first optical lens, and the center thickness CT1 of the first optical lens on the optical axis may satisfy: 13 mm < (N2 / N1)×CT1 < 17 mm.

[0011] In one embodiment, the effective focal length f of the optical system, the Abbe number V2 of the second optical lens, and the Abbe number V1 of the first optical lens may satisfy: 27.5 mm <f×(V2 / V1)<28.5mm。

[0012] In one embodiment, the optical system further includes an aperture, and the optical system further includes an aperture and an image surface provided on the second side, and a distance ER from the aperture to the first side surface of the first optical lens on the optical axis and a distance BFL from the second side surface of the second optical lens to the image surface on the optical axis may satisfy: <ER / BFL<5。

[0013] In one embodiment, the effective focal length f2 of the second optical lens and the curvature radius R4 of the second side surface of the second optical lens may satisfy: |f2 / R4|<3.

[0014] In one embodiment, the center thickness CT2 of the second optical lens on the optical axis and the refractive index N2 of the second optical lens may satisfy: 4.8 mm <CT2 / N2<7.2mm。

[0015] In one embodiment, the distance TD from the first side surface of the first optical lens to the second side surface of the second optical lens on the optical axis and the curvature radius R4 of the second side surface of the second optical lens may satisfy: -0.5 <TD / R4<0.1。

[0016] On the other hand, the present application also provides a VR device, which includes the optical system provided by at least one of the above-mentioned 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 may include, in order from the first side to the second side of the optical axis, a reflective polarizing element, a quarter-wave plate, a first optical lens, a partially reflecting element, and a second optical lens. The reflective polarizing element can reflect light of a certain polarization direction while transmitting light orthogonal to the polarization direction; the quarter-wave plate can change the polarization state of light; and the partially reflecting element can achieve both reflection and transmission. Furthermore, by properly allocating the focal lengths of the first and second optical lenses and properly setting the focal length of the system so that the effective focal length of the second optical lens and the effective focal length of the optical system satisfy 4<|f2 / f|<7, the system's optical path can be refracted, which helps shorten the length of the head-mounted device. Furthermore, by setting the surface of the second optical lens near the second side to be an aspheric surface, the system's aberration correction capability is enhanced, improving the system's imaging performance. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0019] Figure 1 1 shows a schematic structural diagram of an optical system according to Example 1 of the present application;

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

[0021] Figure 3 1 shows a schematic structural diagram of an optical system according to Example 2 of the present application;

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

[0023] Figure 5 1 shows a schematic structural diagram of an optical system according to Example 3 of the present application;

[0024] Figures 6A to 6C axial chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Example 3 are respectively shown;

[0025] Figure 7 1 shows a schematic structural diagram of an optical system according to Example 4 of the present application;

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

[0027] Figure 9 1 shows a schematic structural diagram of an optical system according to Example 5 of the present application;

[0028] 10A to 10C The axial chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Example 5 are shown respectively;

[0029] Figure 11 shows a schematic structural diagram of an optical system according to Example 6 of the present application; and

[0030] 12A to 12C The axial chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Example 6 are respectively shown. DETAILED DESCRIPTION

[0031] For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely descriptions of exemplary embodiments of the present application and are not intended to limit the scope of the present 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 solely to distinguish one feature from another and do not limit the features. Thus, without departing from the teachings of this application, the first optical lens discussed below could also be referred to as the second optical lens, and the second optical lens could also be referred to as the first optical lens.

[0033] In the drawings, the thickness, size, and shape of the lenses are slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical and aspherical surfaces shown in the drawings are provided by way of example. That is, the shapes of the spherical and aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0034] In this article, the paraxial region refers to the region near the optical axis. If a lens surface is convex and the location of the convex surface is undefined, it means that the lens surface is convex at least in the paraxial region; if a lens surface is concave and the location of the concave surface is undefined, it means that the lens surface is concave at least in the paraxial region.

[0035] It should also be understood that the terms "comprises," "including," "having," "includes," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application." And, the term "exemplary" is intended to refer to an example or illustration.

[0036] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and will not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.

[0037] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

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

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

[0040] The following will refer to Figure 1 An example description of the optical system is given below. Figure 1As shown, an optical system according to an exemplary embodiment of the present application may include a reflective polarizer RP, a quarter-wave plate QWP, a first optical lens E1, a partially reflective element BS, and a second optical lens E2, arranged in sequence from a first side to a second side. In actual use, the optical system according to an exemplary embodiment of the present application can be used as a VR lens, in which case 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 surface IMG located on the display side. A light beam emitted from the image surface IMG sequentially passes through the second optical lens E2, the partially reflective element BS, the first optical lens E1, and the quarter-wave plate QWP to reach the reflective polarizer RP. It is reflected at the reflective polarizer RP and passes through the quarter-wave plate QWP and the first optical lens E1 again to reach the partially reflective element BS. Thereafter, the light beam is reflected again at the reflective element BS and sequentially passes through the first optical lens E1, the quarter-wave plate QWP, and the reflective polarizer RP to be emitted toward the human eye side. In an exemplary embodiment, the partially reflective element BS may be a semi-transmissive and semi-reflective film layer coated on the second side surface of the first optical lens E1.

[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, for example, in a head-mounted device. The five optical elements included in the optical system, namely, a reflective polarizer, a quarter-wave plate, a first optical lens, a partially reflective element, and a second optical lens, may be arranged in order along the optical axis from the human eye side to the display side.

[0042] In exemplary embodiments, a surface of the first optical lens close to the display side may be a convex surface or a flat surface.

[0043] In an exemplary embodiment, the second optical lens may have positive or negative optical power. The surface of the second optical lens near the display may be aspherical. Aspherical lenses have a better curvature radius and have the advantages of reducing distortion and astigmatism. Using an aspherical lens can minimize aberrations that occur during imaging, thereby improving image quality.

[0044] In an exemplary embodiment, the optical system of the present application may satisfy the conditional formula 4<|f2 / f|<7, where f2 is the effective focal length of the second optical lens, and f is the effective focal length of the optical system.

[0045] According to the optical system of the exemplary embodiment of the present application, by providing a reflective polarizing element, light with a certain polarization direction can be reflected while light orthogonal to this polarization direction can be transmitted; by providing a quarter-wave plate, the polarization state of light can be changed; by providing a partial reflection element, reflection and transmission can be achieved; and by reasonably distributing the optical powers of the first lens and the second lens and reasonably setting the system focal length so that the effective focal length of the second optical lens and the effective focal length of the optical system satisfy 4 < |f2 / f| < 7, the system optical path can be made to be refractive and reflective, which is beneficial to shortening the length of the head-mounted device; at the same time, by utilizing the aberration correction ability of the aspherical surface of the second lens, it is beneficial to improving the imaging performance of the system.

[0046] In an exemplary embodiment, the optical system of the present application can satisfy the conditional formula 4 < ImgH / EPD < 5, where ImgH is the image height presented on the image plane of the optical system and EPD is the entrance pupil diameter of the optical system. By controlling the ratio of the image height presented on the image plane of the optical system to the entrance pupil diameter of the optical system within this range, on the premise of a certain eye pupil size, the size of the screen can be restricted and the selection direction of the screen can be clarified.

[0047] In an exemplary embodiment, the optical system of the present application may further include an aperture stop, and the optical system of the present application can satisfy the conditional formula 2.3 < SL / CT1 < 3.8, where SL is the distance on the optical axis from the aperture stop to the image plane of the optical system and CT1 is the central thickness on the optical axis of the first optical lens. By controlling the ratio of the distance on the optical axis from the aperture stop to the image plane of the optical system to the central thickness on the optical axis of the first optical lens within this range, on the one hand, it is beneficial to the processing performance of the first optical lens, and on the other hand, it can increase the optical path of light in the first optical lens, which is beneficial to shortening the height of the system.

[0048] In an exemplary embodiment, the optical system of the present application may further include an aperture stop, and the optical system of the present application can satisfy the conditional formula 2.6 < SD / (T12 + CT2) < 5.2, where SD is the distance on the optical axis from the aperture stop to the surface of the second optical lens close to the display side, T12 is the air gap on the optical axis between the first optical lens and the second optical lens, and CT2 is the central thickness on the optical axis of the second optical lens. By controlling the ratio of the distance on the optical axis from the aperture stop to the surface of the second optical lens close to the display side to the sum of the air gap on the optical axis between the first optical lens and the second optical lens and the central thickness on the optical axis of the second optical lens within this range, on the premise of a certain exit pupil distance, the central thickness of the first optical lens is indirectly controlled, which is beneficial to the molding of the first optical lens and the second optical lens.

[0049] In an exemplary embodiment, the optical system of the present application can satisfy the conditional formula 0.95 < TD / ImgH < 1.45, where TD is the distance on the optical axis from the surface of the first optical lens away from the display side to the surface of the second optical lens close to the display side, and ImgH is the image height presented by the image plane of the optical system. By controlling the ratio of the distance on the optical axis from the surface of the first optical lens away from the display side to the surface of the second optical lens close to the display side to the image height presented by the image plane of the optical system within this range, the TTL ratio is controlled, which is beneficial to reducing the size of the head-mounted device while ensuring the performance of the optical system.

[0050] In an exemplary embodiment, the optical system of the present application can satisfy the conditional formula 33 mm < f × tan(FOV / 2) < 37.5 mm, where f is the effective focal length of the optical system and FOV is the maximum field of view angle of the optical system. By controlling the effective focal length of the optical system and the maximum field of view angle of the optical system to satisfy 33 mm < f × tan(FOV / 2) < 37.5 mm, the image height of the system can be controlled and the screen size can be restricted.

[0051] In an exemplary embodiment, the optical system of the present application can satisfy the conditional formula 13 mm < (N2 / N1) × CT1 < 17 mm, where N2 is the refractive index of the second optical lens, N1 is the refractive index of the first optical lens, and CT1 is the central thickness of the first optical lens on the optical axis. By controlling the refractive index of the second optical lens, the refractive index of the first optical lens, and the central thickness of the first optical lens on the optical axis to satisfy 13 mm < (N2 / N1) × CT1 < 17 mm, the optical power of the first lens and the second lens can be controlled, and the focal length of the system can be controlled, thereby restricting the field of view angle of the system and meeting the purpose of a wide angle of the head-mounted device.

[0052] In an exemplary embodiment, the optical system of the present application can satisfy the conditional formula 27.5 mm < f × (V2 / V1) < 28.5 mm, where f is the effective focal length of the optical system, V2 is the Abbe number of the second optical lens, and V1 is the Abbe number of the first optical lens. By controlling the effective focal length of the optical system, the Abbe number of the second optical lens, and the Abbe number of the first optical lens to satisfy 27.5 mm < f × (V2 / V1) < 28.5 mm, it is beneficial to correct the chromatic aberration of the system and improve the imaging quality of the system while meeting the focal length of the system.

[0053] In an exemplary embodiment, the optical system of the present application can satisfy the conditional formula 4 < ER / BFL < 5, where ER is the distance on the optical axis from the aperture stop of the optical system to the surface of the first optical lens on the side away from the display, and BFL is the distance on the optical axis from the surface of the second optical lens on the side close to the display to the image plane of the optical system. By controlling the ratio of the distance on the optical axis from the aperture stop to the surface of the first optical lens on the side away from the display to the distance on the optical axis from the surface of the second optical lens on the side close to the display to the image plane of the optical system within this range, on the one hand, the viewing distance requirements of the head-mounted device are met, and on the other hand, the back focal length of the system is controlled, avoiding the risk of interference between the optical lens assembly and the screen.

[0054] In an exemplary embodiment, the optical system of the present application can satisfy the conditional formula |f2 / R4| < 3, where f2 is the effective focal length of the second optical lens and R4 is the radius of curvature of the surface of the second optical lens on the side close to the display. By controlling the absolute value of the ratio of the effective focal length of the second optical lens to the radius of curvature of the surface of the second optical lens on the side close to the display within this range, the shape of the second optical lens can be restricted, which is beneficial to reducing the sensitivity of the second optical lens, thereby improving the assembly yield.

[0055] In an exemplary embodiment, the optical system of the present application can satisfy the conditional formula 4.8 mm < CT2 / N2 < 7.2 mm, where CT2 is the central thickness of the second optical lens on the optical axis and N2 is the refractive index of the second optical lens. By controlling the ratio of the central thickness of the second optical lens on the optical axis to the refractive index of the second optical lens within this range, on the one hand, it is beneficial to select low-stress materials; on the other hand, considering that the lens aperture is relatively large, appropriately increasing the central thickness is beneficial to lens forming.

[0056] In an exemplary embodiment, the optical system of the present application can satisfy the conditional formula -0.5 < TD / R4 < 0.1, where TD is the distance on the optical axis from the surface of the first optical lens on the side away from the display to the surface of the second optical lens on the side close to the display, and R4 is the radius of curvature of the surface of the second optical lens on the side close to the display. By controlling the ratio of the distance on the optical axis from the surface of the first optical lens on the side away from the display to the surface of the second optical lens on the side close to the display to the radius of curvature of the surface of the second optical lens on the side close to the display within this range, the back focal length of the system can be controlled, thereby controlling the total length of the system and meeting the miniaturization goal of the head-mounted device.

[0057] In an exemplary embodiment, the optical system of the present application can include at least one aperture stop. The aperture stop can restrict the light path and control the light intensity. The aperture stop can be set at an appropriate position in the optical system. For example, the aperture stop can be located between the human eye side and the reflective polarizing element.

[0058] In an exemplary embodiment, optionally, the optical system may further include a 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 28.00 mm to 28.15 mm, and the effective focal length f2 of the second optical lens may be, for example, in the range of -164.96 mm to 178.91 mm.

[0060] According to the optical system of the above-mentioned embodiment of the present application, by setting a reflective polarizing element, light of a certain polarization direction can be reflected, and light orthogonal to the polarization direction can be transmitted; by setting a quarter-wave plate, the polarization state of light can be changed; by setting a partial reflective element, reflection and transmission can be achieved; and, by reasonably allocating the optical focal length of the first lens and the second lens, and reasonably setting the focal length of the system, the effective focal length of the second optical lens and the effective focal length of the optical system satisfy 4<|f2 / f|<7, the system optical path can be refracted, which is beneficial to shortening the length of the head-mounted device; at the same time, the aberration correction capability of the aspheric surface of the second lens is utilized to improve the imaging performance of the system.

[0061] According to some embodiments of the present application, by properly setting parameters such as the optical system's effective focal length, maximum field of view angle, image height presented by the image plane, entrance pupil diameter, and lens center thickness, refractive index, Abbe number, and radius of curvature, and by properly setting parameters such as the aperture, lens, and distance between image planes, the screen size can be constrained and the screen's orientation can be clearly defined. This can satisfy the wide-angle requirements of the head-mounted device, meet the viewing distance requirements of the head-mounted device, and properly control the system's back focus to avoid the risk of interference between the optical lens assembly and the screen. This can also improve the processing and molding performance of the lens, reduce lens sensitivity, and improve assembly yield. It can also facilitate correction of system chromatic aberration, improving system imaging quality, and meet the goal of miniaturization of the head-mounted device while ensuring the performance of the optical system.

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

[0063] Example 1

[0064] The following reference Figures 1 to 2C An optical system according to Example 1 of the present application is described. Figure 1 A structural schematic diagram of an optical system according to Example 1 of the present application is shown.

[0065] like Figure 1As shown, the optical system includes, in order from the human eye side to the display side along the optical axis: a reflective polarizer RP, a quarter-wave plate QWP, a first optical lens E1, a partially reflecting element BS and a second optical lens E2.

[0066] In this embodiment, the surface of the first optical lens E1 close to the human eye is flat, and the surface close to the display is convex. The second optical lens E2 has positive refractive power, and the surface close to the human eye is convex, and the surface close to the display is concave.

[0067] Table 1 shows basic parameters of the optical system of Example 1, wherein the units of the curvature radius and thickness are both millimeters (mm).

[0068] surface element Surface type Radius of curvature thickness Refractive index Abbe number Refraction / Reflection S0 spherical surface endless endless refraction S1 Aperture (STO) spherical surface endless 15.0000 refraction S2 Reflective polarizer (RP) spherical surface endless 0.2000 1.50 57.00 refraction S3 Quarter Wave Plate (QWP) spherical surface endless 0.2000 1.50 57.00 refraction S4 First optical lens (E1) spherical surface endless 16.6406 1.54 56.05 refraction S5 Partially reflective element (BS) Aspheric -101.0049 -16.6406 1.54 56.05 reflection S6 Quarter Wave Plate (QWP) spherical surface endless -0.2000 1.50 57.00 refraction S7 Reflective polarizer (RP) spherical surface endless 0.2000 1.50 57.00 reflection S8 First optical lens (E1) spherical surface endless 16.6406 1.54 56.05 refraction S9 Aspheric -101.0049 0.1000 refraction S10 Second optical lens (E2) Aspheric 66.5304 7.7003 1.54 56.05 refraction S11 Aspheric 11475.8452 0.5018 refraction S12 spherical surface endless 0.0000 refraction S13 spherical surface endless 3.0800 refraction S14 Image surface (IMG) spherical surface endless 0.0000 refraction

[0069] Table 1

[0070] In Example 1, the surface S5 of the first optical lens E1 close to the display side, and the surface S10 and the surface S11 of the second optical lens E2 close to the human eye side are all aspherical surfaces. The surface shape x of each aspherical lens can be defined by, but is not limited to, the following aspherical formula:

[0071]

[0072] Wherein, x is the distance vector height of the aspheric surface from the vertex of the aspheric surface at a height of h along the optical axis; c is the paraxial curvature of the aspheric surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the curvature radius R in Table 1 above); k is the conic coefficient; Ai is the correction coefficient of the i-th order of the aspheric surface. Table 2 below lists the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, A22, A23, A24, A25, A26, A27, A28, A29, A30, A31, A32, A33, A34, A35, A36, A37, A38, A39 10 、A 12 、A 14 、A 16 、A 18 and A 20 .

[0073]

[0074]

[0075] Table 2

[0076] Figure 2A The axial chromatic aberration curve of the optical system of Example 1 is shown, which indicates the deviation of the convergent focus of light of different wavelengths passing through the lens. Figure 2B The astigmatism curve of the optical system of Example 1 is shown, which indicates meridional field curvature and sagittal field curvature. Figure 2CThe distortion curve of the optical system of Example 1 is shown, which represents the distortion value corresponding to different field angles. Figures 2A to 2C It can be seen that the optical system provided in Example 1 can achieve good imaging quality.

[0077] Example 2

[0078] The following reference Figures 3 to 4C The optical system according to Example 2 of the present application is described. In this embodiment and the following embodiments, some descriptions similar to those in Example 1 will be omitted for the sake of brevity. Figure 3 A structural schematic diagram of an optical system according to Example 2 of the present application is shown.

[0079] like Figure 3 As shown, the optical system includes, in order from the human eye side to the display side along the optical axis: a reflective polarizer RP, a quarter-wave plate QWP, a first optical lens E1, a partially reflecting element BS and a second optical lens E2.

[0080] In this embodiment, the surface of the first optical lens E1 close to the human eye is concave, and the surface close to the display is convex. The second optical lens E2 has negative optical power, and the surface close to the human eye is convex, and the surface close to the display is convex.

[0081] Table 3 shows the basic parameters of the optical system of Example 2, where the units of the curvature radius and thickness are both in millimeters (mm). In this embodiment, the surface S4 near the human eye side and the surface S5 near the display side of the first optical lens E1, as well as the surface S10 near the human eye side and the surface S11 near the display side of the second optical lens E2 are all aspherical surfaces. Table 4 shows the high-order coefficients A4, A6, A8, A9, A10, A11 of the aspherical mirror surfaces S4, S5, S10, and S11 that can be used in Example 2. 10 、A 12 、A 14 、A 16 、A 18 and A 20 , wherein each aspheric surface shape can be defined by formula (1) given in the above embodiment 1.

[0082] surface element Surface type Radius of curvature thickness Refractive index Abbe number Refraction / Reflection S0 spherical surface endless endless refraction S1 Aperture (STO) spherical surface endless 15.0000 refraction S2 Reflective polarizer (RP) Aspheric -1270458.6191 0.2000 1.50 57.00 refraction S3 Quarter Wave Plate (QWP) Aspheric -1270458.6191 0.2000 1.50 57.00 refraction S4 First optical lens (E1) Aspheric -1270458.6191 14.8000 1.54 56.05 refraction S5 Partially reflective element (BS) Aspheric -100.6171 -14.8000 1.54 56.05 reflection S6 Quarter Wave Plate (QWP) Aspheric -1270458.6191 -0.2000 1.50 57.00 refraction S7 Reflective polarizer (RP) Aspheric -1270458.6191 0.2000 1.50 57.00 reflection S8 First optical lens (E1) Aspheric -1270458.6191 14.8000 1.50 57.00 refraction S9 Aspheric -100.6171 0.1000 refraction S10 Second optical lens (E2) Aspheric 69.6859 10.5234 1.54 56.05 refraction S11 Aspheric -139.6230 0.2195 refraction S12 spherical surface endless 0.0000 refraction S13 spherical surface endless 2.9420 refraction S14 Image surface (IMG) spherical surface endless 0.0000 refraction

[0083] Table 3

[0084]

[0085]

[0086] Table 4

[0087] Figure 4AThe axial chromatic aberration curve of the optical system of Example 2 is shown, which indicates the deviation of the convergent focus of light of different wavelengths after passing through the lens. Figure 4B The astigmatism curve of the optical system of Example 2 is shown, which indicates meridional field curvature and sagittal field curvature. Figure 4C The distortion curve of the optical system of Example 2 is shown, which represents the distortion value corresponding to different field angles. Figures 4A to 4C It can be seen that the optical system provided in Example 2 can achieve good imaging quality.

[0088] Example 3

[0089] The following reference Figures 5 to 6C An optical system according to Example 3 of the present application is described. Figure 5 A structural schematic diagram of an optical system according to Example 3 of the present application is shown.

[0090] like Figure 5 As shown, the optical system includes, in order from the human eye side to the display side along the optical axis: a reflective polarizer RP, a quarter-wave plate QWP, a first optical lens E1, a partially reflecting element BS and a second optical lens E2.

[0091] In this embodiment, the surface of the first optical lens E1 close to the human eye is concave, and the surface close to the display is convex. The second optical lens E2 has negative optical power, and the surface close to the human eye is concave, and the surface close to the display is convex.

[0092] Table 5 shows the basic parameters of the optical system of Example 3, where the units of the curvature radius and thickness are both in millimeters (mm). In this embodiment, the surface S4 and the surface S5 of the first optical lens E1 close to the human eye side and the surface S10 and the surface S11 of the second optical lens E2 close to the human eye side and the surface S12 close to the display side are all aspherical surfaces. Table 6 shows the high-order coefficients A4, A6, A8, A9, A10, A11 of the aspherical mirror surfaces S4, S5, S10, and S11 that can be used in Example 3. 10 、A 12 、A 14 、A 16 、A 18 and A 20 , wherein each aspheric surface shape can be defined by formula (1) given in the above embodiment 1.

[0093] surface element Surface type Radius of curvature thickness Refractive index Abbe number Refraction / Reflection S0 spherical surface endless endless refraction S1 Aperture (STO) spherical surface endless 15.0000 refraction S2 Reflective polarizer (RP) Aspheric -350.0000 0.2000 1.50 57.00 refraction S3 Quarter Wave Plate (QWP) Aspheric -350.0000 0.2000 1.50 57.00 refraction S4 First optical lens (E1) Aspheric -350.0000 13.7000 1.54 56.05 refraction S5 Partially reflective element (BS) Aspheric -84.5682 -13.7000 1.54 56.05 reflection S6 Quarter Wave Plate (QWP) Aspheric -350.0000 -0.2000 1.50 57.00 refraction S7 Reflective polarizer (RP) Aspheric -350.0000 0.2000 1.50 57.00 reflection S8 First optical lens (E1) Aspheric -350.0000 13.7000 1.50 57.00 refraction S9 Aspheric -84.5682 0.1000 refraction S10 Second optical lens (E2) Aspheric -733.4362 10.9826 1.54 56.05 refraction S11 Aspheric -51.0995 0.1923 refraction S12 spherical surface endless 0.0000 refraction S13 spherical surface endless 3.0000 refraction S14 Image surface (IMG) spherical surface endless 0.0000 refraction

[0094] Table 5

[0095]

[0096]

[0097] Table 6

[0098] Figure 6A The axial chromatic aberration curve of the optical system of Example 3 is shown, which indicates the deviation of the convergent focus of light of different wavelengths passing through the lens. Figure 6B The astigmatism curve of the optical system of Example 3 is shown, which indicates the meridional field curvature and the sagittal field curvature. Figure 6C The distortion curve of the optical system of Example 3 is shown, which represents the distortion value corresponding to different field angles. Figures 6A to 6C It can be seen that the optical system provided in Example 3 can achieve good imaging quality.

[0099] Example 4

[0100] The following reference Figures 7 to 8C An optical system according to Example 4 of the present application is described. Figure 7 A structural schematic diagram of an optical system according to Example 4 of the present application is shown.

[0101] like Figure 7 As shown, the optical system includes, in order from the human eye side to the display side along the optical axis: a reflective polarizer RP, a quarter-wave plate QWP, a first optical lens E1, a partially reflecting element BS and a second optical lens E2.

[0102] In this embodiment, the surface of the first optical lens E1 close to the human eye is convex, and the surface close to the display is also convex. The second optical lens E2 has negative optical power, and the surface close to the human eye is convex, and the surface close to the display is also convex.

[0103] Table 7 shows the basic parameters of the optical system of Example 4, where the units of the curvature radius and thickness are both in millimeters (mm). In this embodiment, the surface S4 and the surface S5 of the first optical lens E1 close to the human eye side and the surface S10 and the surface S11 of the second optical lens E2 close to the human eye side and the surface S12 close to the display side are all aspherical surfaces. Table 8 shows the high-order coefficients A4, A6, A8, A9, A10, A11 of the aspherical mirror surfaces S4, S5, S10, and S11 that can be used in Example 4. 10 、A 12 、A 14 、A 16 、A 18 and A 20 , wherein each aspheric surface shape can be defined by formula (1) given in the above embodiment 1.

[0104] surface element Surface type Radius of curvature thickness Refractive index Abbe number Refraction / Reflection S0 spherical surface endless endless refraction S1 Aperture (STO) spherical surface endless 15.0000 refraction S2 Reflective polarizer (RP) Aspheric 143.4015 0.2000 1.50 57.00 refraction S3 Quarter Wave Plate (QWP) Aspheric 143.4015 0.2000 1.50 57.00 refraction S4 First optical lens (E1) Aspheric 143.4015 15.3000 1.54 56.05 refraction S5 Partially reflective element (BS) Aspheric -250.0000 -15.3000 1.54 56.05 reflection S6 Quarter Wave Plate (QWP) Aspheric 143.4015 -0.2000 1.50 57.00 refraction S7 Reflective polarizer (RP) Aspheric 143.4015 0.2000 1.50 57.00 reflection S8 First optical lens (E1) Aspheric 143.4015 15.3000 1.54 56.05 refraction S9 Aspheric -250.0000 2.6562 refraction S10 Second optical lens (E2) Aspheric 49.2252 10.5446 1.54 56.05 refraction S11 Aspheric -413.7541 0.3805 refraction S12 spherical surface endless 0.0000 refraction S13 spherical surface endless 3.0000 refraction S14 Image surface (IMG) spherical surface endless 0.0000 refraction

[0105] Table 7

[0106] Coefficient\Surface S4 S5 S10 S11 A4 -4.6422E-07 0.0000E+00 0.0000E+00 5.5702E+00 A6 1.9527E-10 0.0000E+00 0.0000E+00 -4.6946E+00 A8 -4.8667E-14 0.0000E+00 0.0000E+00 4.3508E+00 A10 -4.3697E-17 0.0000E+00 0.0000E+00 -1.8064E+00 A12 1.6331E-20 0.0000E+00 0.0000E+00 2.1385E+00 A14 0.0000E+00 0.0000E+00 0.0000E+00 -6.6503E-01 A16 0.0000E+00 0.0000E+00 0.0000E+00 7.7794E-01 A18 0.0000E+00 0.0000E+00 0.0000E+00 -1.5969E-01 A20 0.0000E+00 0.0000E+00 0.0000E+00 1.5426E-01

[0107] Table 8

[0108] Figure 8A The axial chromatic aberration curve of the optical system of Example 4 is shown, which indicates the deviation of the convergent focus of light of different wavelengths passing through the lens. Figure 8B The astigmatism curve of the optical system of Example 4 is shown, which indicates the meridional field curvature and the sagittal field curvature. Figure 8C The distortion curve of the optical system of Example 4 is shown, which represents the distortion value corresponding to different field angles. Figures 8A to 8C It can be seen that the optical system provided in Example 4 can achieve good imaging quality.

[0109] Example 5

[0110] The following reference Figures 9 to 10C An optical system according to Example 5 of the present application is described. Figure 9 A structural schematic diagram of an optical system according to Example 5 of the present application is shown.

[0111] like Figure 9 As shown, the optical system includes, in order from the human eye side to the display side along the optical axis: a reflective polarizer RP, a quarter-wave plate QWP, a first optical lens E1, a partially reflecting element BS and a second optical lens E2.

[0112] In this embodiment, the surface of the first optical lens E1 close to the human eye is convex, and the surface close to the display is flat. The second optical lens E2 has negative optical power, and the surface close to the human eye is convex, and the surface close to the display is concave.

[0113] Table 9 shows the basic parameters of the optical system of Example 5, where the units of the curvature radius and thickness are both in millimeters (mm). In this embodiment, the surface S4 of the first optical lens E1 close to the human eye side and the surface S10 and the surface S11 close to the display side of the second optical lens E2 are all aspherical surfaces. Table 10 shows the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, A22, A23, A24, A25, A26, A27, A28, A29, A30, A31, A32, A33, A34, A35, A36, A37, A38, A39, A40, A41, A42, A43, A44, A45, A46, A47, A48, A49, A50, A51, A52, A53, A54, A55, A56, A57, A58, A59, A60, A61, A71, A72, A73, A74, A75 10 、A 12 、A 14 、A 16 、A 18 and A 20 , wherein each aspheric surface shape can be defined by formula (1) given in the above embodiment 1.

[0114] surface element Surface type Radius of curvature thickness Refractive index Abbe number Refraction / Reflection S0 spherical surface endless endless refraction S1 Aperture (STO) spherical surface endless 15.0000 refraction S2 Reflective polarizer (RP) Aspheric 97.7411 0.2000 1.50 57.00 refraction S3 Quarter Wave Plate (QWP) Aspheric 97.7411 0.2000 1.50 57.00 refraction S4 First optical lens (E1) Aspheric 97.7411 13.6550 1.54 56.05 refraction S5 Partially reflective element (BS) spherical surface endless -13.6550 1.54 56.05 reflection S6 Quarter Wave Plate (QWP) Aspheric 97.7411 -0.2000 1.50 57.00 refraction S7 Reflective polarizer (RP) Aspheric 97.7411 0.2000 1.50 57.00 reflection S8 First optical lens (E1) Aspheric 97.7411 13.6550 1.54 56.05 refraction S9 spherical surface endless 7.2054 refraction S10 Second optical lens (E2) Aspheric 49.2252 9.3914 1.54 56.05 refraction S11 Aspheric 361.7565 0.3179 refraction S12 spherical surface endless 0.0000 refraction S13 spherical surface endless 3.0000 refraction S14 Image surface (IMG) spherical surface endless 0.0000 refraction

[0115] Table 9

[0116] Coefficient\Surface S4 S10 S11 A4 -3.4192E-07 0.0000E+00 -1.0454E+00 A6 2.1221E-10 0.0000E+00 -1.8815E+00 A8 -1.6481E-13 0.0000E+00 2.6627E+00 A10 2.1706E-17 0.0000E+00 -1.3585E+00 A12 1.0446E-20 0.0000E+00 2.1617E+00 A14 0.0000E+00 0.0000E+00 -9.5275E-01 A16 0.0000E+00 0.0000E+00 9.5462E-01 A18 0.0000E+00 0.0000E+00 -2.7688E-01 A20 0.0000E+00 0.0000E+00 1.7237E-01

[0117] Table 10

[0118] Figure 10A The axial chromatic aberration curve of the optical system of Example 5 is shown, which indicates the deviation of the convergent focus of light of different wavelengths passing through the lens. Figure 10B The astigmatism curve of the optical system of Example 5 is shown, which indicates the meridional field curvature and the sagittal field curvature. Figure 10C The distortion curve of the optical system of Example 5 is shown, which represents the distortion value corresponding to different field angles. 10A to 10C It can be seen that the optical system provided in Example 5 can achieve good imaging quality.

[0119] Example 6

[0120] The following reference Figures 11 to 12C An optical system according to Example 6 of the present application is described. Figure 11 A structural schematic diagram of an optical system according to Example 6 of the present application is shown.

[0121] like Figure 11 As shown, the optical system includes, in order from the human eye side to the display side along the optical axis: a reflective polarizer RP, a quarter-wave plate QWP, a first optical lens E1, a partially reflecting element BS and a second optical lens E2.

[0122] In this embodiment, the surface of the first optical lens E1 close to the human eye is convex, and the surface close to the display is flat. The second optical lens E2 has positive refractive power, and the surface close to the human eye is flat, and the surface close to the display is convex.

[0123] Table 11 shows the basic parameters of the optical system of Example 6, where the units of curvature radius and thickness are both in millimeters (mm). In this embodiment, the surface S4 of the first optical lens E1 close to the human eye and the surface S11 of the second optical lens E2 close to the display are both aspherical. Table 12 shows the high-order coefficients A4, A6, A8, A9, A10, A111 of the aspherical mirror surfaces S4 and S11 that can be used in Example 6. 10 、A 12 、A 14 、A 16 、A 18 and A 20 , wherein each aspheric surface shape can be defined by formula (1) given in the above embodiment 1.

[0124] surface element Surface type Radius of curvature thickness Refractive index Abbe number Refraction / Reflection S0 spherical surface endless endless refraction S1 Aperture (STO) spherical surface endless 15.0000 refraction S2 Reflective polarizer (RP) Aspheric 94.3701 0.2000 1.50 57.00 refraction S3 Quarter Wave Plate (QWP) Aspheric 94.3701 0.2000 1.50 57.00 refraction S4 First optical lens (E1) Aspheric 94.3701 13.7200 1.54 56.05 refraction S5 Partially reflective element (BS) spherical surface endless -13.7200 1.54 56.05 reflection S6 Quarter Wave Plate (QWP) Aspheric 94.3701 -0.2000 1.50 57.00 refraction S7 Reflective polarizer (RP) Aspheric 94.3701 0.2000 1.50 57.00 reflection S8 First optical lens (E1) Aspheric 94.3701 13.7200 1.54 56.05 refraction S9 spherical surface endless 7.0476 refraction S10 Second optical lens (E2) spherical surface endless 9.6717 1.54 56.05 refraction S11 Aspheric -65.1340 0.1000 refraction S12 spherical surface endless 0.0000 refraction S13 spherical surface endless 3.0322 refraction S14 Image surface (IMG) spherical surface endless 0.0000 refraction

[0125] Table 11

[0126] Coefficient\Surface S4 S11 A4 -5.4467E-07 -5.0599E-01 A6 1.9270E-10 -2.5871E+00 A8 -1.4347E-13 1.4475E+00 A10 2.9316E-18 -1.0359E+00 A12 1.4951E-20 1.0811E+00 A14 0.0000E+00 -3.9508E-01 A16 0.0000E+00 5.1408E-01 A18 0.0000E+00 -5.2743E-02 A20 0.0000E+00 1.5517E-01

[0127] Table 12

[0128] Figure 12A The axial chromatic aberration curve of the optical system of Example 6 is shown, which indicates the deviation of the convergent focus of light of different wavelengths passing through the lens. Figure 12B The astigmatism curve of the optical system of Example 6 is shown, which indicates the meridional field curvature and the sagittal field curvature. Figure 12C The distortion curve of the optical system of Example 6 is shown, which represents the distortion value corresponding to different field angles. 12A to 12C It can be seen that the optical system provided in Example 6 can achieve good imaging quality.

[0129] In addition, in Examples 1 to 6, the effective focal length value f2 of the second optical lens, the effective focal length f of the optical system, the image height ImgH presented by the image surface of the optical system, the maximum field of view FOV of the optical system, the entrance pupil diameter EPD of the optical system, the distance SL from the aperture to the image surface of the optical system on the optical axis, the distance SD from the aperture to the surface of the second optical lens close to the display side on the optical axis, the distance TD from the surface of the first optical lens away from the display side to the surface of the second optical lens close to the display side on the optical axis, the distance BFL from the surface of the second optical lens close to the display side to the image surface of the optical system on the optical axis, and the distance ER from the aperture to the surface of the first optical lens away from the display side on the optical axis are as shown in Table 13.

[0130] Parameters / Example 1 2 3 4 5 6 f2(mm) 135.84 -128.32 -134.63 -115.76 -164.96 178.91 f(mm) 28.00 28.15 28.14 28.02 28.02 28.00 ImgH(mm) 24.24 22.19 22.24 21.90 22.81 21.67 FOV(°) 106.0 100.0 100.0 100.0 106.0 100.0 EPD(mm) 5.00 5.00 5.00 5.00 5.00 5.00 SL(mm) 43.42 43.98 43.37 47.28 48.97 48.97 SD(mm) 39.84 40.82 40.18 43.90 45.65 45.84 TD(mm) 24.44 25.42 24.78 28.50 30.25 30.44 BFL(mm) 3.58 3.16 3.19 3.38 3.32 3.13 ER(mm) 15.40 15.40 15.40 15.40 15.40 15.40

[0131] Table 13

[0132] Examples 1 to 6 respectively satisfy the conditions shown in Table 14.

[0133]

[0134]

[0135] Table 14

[0136] The above description is merely a preferred embodiment of the present application and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of protection provided in this application is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the concept of this application. For example, a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An optical system, characterized in that The optical axis includes, in order from the first side to the second side: Reflective polarizing element; quarter wave plate; The first optical lens has positive optical power, and the second side surface thereof is convex or flat; a partially reflective element; and The second optical lens has positive or negative optical power, the second side surface of which is aspherical, and the effective focal length f2 of the second optical lens and the effective focal length f of the optical system satisfy 4.13≤ f2 / f ≤6.39; The refractive index N2 of the second optical lens, the refractive index N1 of the first optical lens, and the center thickness CT1 of the first optical lens on the optical axis satisfy: 13.66 mm ≤ (N2 / N1) × CT1 ≤ 16.64 mm; The optical system further includes an image plane disposed on the second side; The number of lenses having optical power in the optical system is two.

2. The optical system according to claim 1, wherein: The image height ImgH presented by the image plane and the entrance pupil diameter EPD of the optical system satisfy: 4.33≤ImgH / EPD≤4.

85.

3. The optical system according to claim 1, wherein: The optical system further includes a stop, and a distance SL from the stop to the image plane of the optical system on the optical axis and a center thickness CT1 of the first optical lens on the optical axis satisfy: 2.61≤SL / CT1≤3.

59.

4. The optical system according to claim 1, wherein The optical system further includes an aperture, wherein a distance SD from the aperture to the second side surface of the second optical lens on the optical axis, an air gap T12 between the first optical lens and the second optical lens on the optical axis, and a center thickness CT2 of the second optical lens on the optical axis satisfy the following conditions: 2.74≤SD / (T12+CT2)≤5.

11.

5. The optical system according to claim 1, wherein: The distance TD from the first side surface of the first optical lens to the second side surface of the second optical lens on the optical axis and the image height ImgH presented by the image surface of the optical system satisfy: 1.01≤TD / ImgH≤1.

40.

6. The optical system according to claim 1, wherein: The effective focal length f of the optical system and the maximum field of view FOV of the optical system satisfy: 33.37mm≤f×tan(FOV / 2)≤37.18mm.

7. The optical system according to claim 1, wherein: The effective focal length f of the optical system, the Abbe number V2 of the second optical lens, and the Abbe number V1 of the first optical lens satisfy: 28.00mm≤f×(V2 / V1)≤28.15mm.

8. The optical system according to claim 1, wherein: The optical system further includes an aperture and an image plane disposed on the second side, wherein a distance ER from the aperture to the first side surface of the first optical lens on the optical axis and a distance BFL from the second side surface of the second optical lens to the image plane on the optical axis satisfy: 4.30≤ER / BFL≤4.

92.

9. The optical system according to claim 1, wherein: The effective focal length f2 of the second optical lens and the curvature radius R4 of the second side surface of the second optical lens satisfy: f2 / R4 ≤2.75。 10. The optical system according to claim 1, wherein: The center thickness CT2 of the second optical lens on the optical axis and the refractive index N2 of the second optical lens satisfy: 5.00mm≤CT2 / N2≤7.13mm.

11. The optical system according to claim 1, wherein: The distance TD from the first side surface of the first optical lens to the second side surface of the second optical lens on the optical axis and the curvature radius R4 of the second side surface of the second optical lens satisfy: -0.5 <TD / R4<0.1。 12. A VR device comprising the optical system according to at least one of claims 1 to 11, wherein: The first side is a human eye side, and the second side is a display side.

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