An optical system

Abstract

The present application discloses an optical system, comprising: a first lens, a reflective polarizing element, a quarter-wave plate, a second lens, a third lens, and a display; wherein, the first lens to the third lens are arranged in sequence along the optical axis from a position far from the display to a position close to the display; the reflective polarizing element and the quarter-wave plate are disposed between the first lens and the second lens; each of the first lens to the third lens has at least one far-light surface far from the display and at least one near-light surface close to the display; a partial reflection layer is provided on the far-light surface or the near-light surface of at least one lens; wherein, the effective focal length f of the optical system and the combined focal length F12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens satisfy: 0.5 < f / F12 < 1.5. It reflects light of a certain polarization direction while transmitting light orthogonal to this polarization direction; it adds a phase delay to the polarized light, thereby changing the polarization state of the light; it realizes reflection and transmission; it can achieve a U-turn and shorten the length of the optical system.

Description

Technical Field

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

[0002] Since the concept of the "metaverse" was proposed, AR / VR has ushered in a second opportunity for development. As the entry point for human-computer interaction, VR imaging lenses play a crucial role. Currently, there are three main types of VR imaging lenses: aspherical, Fresnel, and folded optical path. Among them, the folded optical path solution can achieve the thinning and lightening of visual optical system devices and is the main direction for VR lenses.

[0003] The folded optical path solution reduces the length of the visual optics device by folding the optical path. However, the two-piece folded optical path lens devices currently available have poor image quality at the edges of the field of view, which seriously affects the user experience. Therefore, this application designs a three-piece folded optical path solution, which further improves the image quality at the edges of the field of view while reducing the system length. Summary of the Invention

[0004] This application aims to provide an optical system that improves the poor edge field-of-view imaging quality of two-lens systems by employing three lenses.

[0005] This application provides an optical system comprising: a first lens, a reflective polarizing element, a quarter-wave plate, a second lens, a third lens, and a display; wherein the first lens to the third lens are arranged sequentially along the optical axis from the position furthest from the display to the position closest to the display; the reflective polarizing element and the quarter-wave plate are disposed between the first lens and the second lens; each of the first lens to the third lens has at least one far-light surface furthest from the display and one near-light surface close to the display; the far-light surface or the near-light surface of the at least one lens has a partially reflective layer; wherein the effective focal length f of the optical system, and the combined focal length F12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens, satisfy: 0.5 <f / F12<1.5。

[0006] This application also provides an optical system comprising: a first lens, a reflective polarizing element, a quarter-wave plate, a second lens, a third lens, and a display; the first lens to the third lens are arranged sequentially along the optical axis from the position furthest from the display to the position closest to the display; the reflective polarizing element and the quarter-wave plate are positioned between the first lens and the second lens; each of the first lens to the third lens has at least one far-light surface furthest from the display and one near-light surface close to the display; the far-light surface or the near-light surface of the at least one lens has a partially reflective layer; wherein the effective focal length f of the optical system and the focal length f3 of the third lens satisfy: -20.0 <f3 / f<30.0。

[0007] According to one embodiment of this application, the axial distance TD between the far-light surface of the first lens and the near-light surface of the third lens satisfies the following condition: 0.3 <TD / f<1.0。

[0008] According to one embodiment of this application, the refractive index N1 of the first lens, the refractive index N2 of the second lens, and the refractive index N3 of the third lens satisfy: 1.5 < (N1 + N2) / N3 < 2.1.

[0009] According to one embodiment of this application, the reflective polarizing element includes at least one far-light surface away from the display and at least one near-light surface close to the display; the quarter-wave plate includes at least one far-light surface away from the display and at least one near-light surface close to the display.

[0010] The near-light surface of the reflective polarizing element is in at least partial contact with the far-light surface of the quarter-wave plate.

[0011] According to one embodiment of this application, the reflective polarizing element includes at least one far-light surface away from the display and at least one near-light surface close to the display; the far-light surface of the reflective polarizing element is at least partially in contact with the near-light surface of the first lens.

[0012] According to one embodiment of this application, the dispersion coefficient V1 of the first lens, the dispersion coefficient V2 of the second lens, the center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, and the distance T12 between the near-light surface of the first lens and the far-light surface of the second lens on the optical axis satisfy: 30.0 < (V1×CT1 + V2×CT2) / (CT1 + T12 + CT2) < 60.0.

[0013] According to one embodiment of this application, the effective focal length f of the optical system and the distance FL between the near-light surface of the third lens and the display on the optical axis satisfy: 1.0 <f / FL<10.0。

[0014] According to one embodiment of this application, the dispersion coefficient V3 of the third lens and the refractive index N3 of the third lens satisfy: 10.0 <V3 / N3<50.0。

[0015] According to one embodiment of this application, the radius of curvature R5 of the far-light surface of the third lens and the radius of curvature R6 of the near-light surface of the third lens satisfy: -1.0 < (R5-R6) / (R5+R6) < 1.0.

[0016] According to one embodiment of this application, the distance T23 between the near-light surface of the second lens and the far-light surface of the third lens on the optical axis, and the center thickness CT3 of the third lens on the optical axis, satisfy: 0 <T23 / CT3<1.5。

[0017] According to one embodiment of this application, the partial reflective layer is coated on the near-light surface or the far-light surface of the third lens.

[0018] According to one embodiment of this application, the refractive index NRP of the reflective polarizing element, the refractive index NQWP of the quarter-wave plate, the refractive index N1 of the first lens, and the refractive index N2 of the second lens satisfy: 0.8 < (NRP + NQWP) / (N1 + N2) < 1.2.

[0019] According to one embodiment of this application, the radius of curvature R1 of the far-light surface of the first lens and the radius of curvature R4 of the near-light surface of the second lens satisfy: 0.2 < (R1 + R4) / (R1 - R4) < 1.2.

[0020] According to one embodiment of this application, the dispersion coefficient VRP of the reflective polarizing element, the dispersion coefficient VQWP of the quarter-wave plate, the center thickness CTR of the reflective polarizing element on the optical axis, the center thickness CTQWP of the quarter-wave plate on the optical axis, and the combined focal length F12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens satisfy:

[0021] 1.2<(VRP+VQWP)×(CTR+CTQWP) / F12<2.0.

[0022] According to one embodiment of this application, the maximum effective radius DT31 of the far-light surface of the third lens and the maximum effective radius DT32 of the near-light surface of the third lens satisfy: -0.5<(DT31+DT32) / f3<0.5.

[0023] According to one embodiment of this application, the axial distance SAG31 between the intersection of the far-light surface and the optical axis of the third lens and the vertex of the effective radius of the far-light surface of the third lens, and the axial distance SAG32 between the intersection of the near-light surface and the optical axis of the third lens and the vertex of the effective radius of the near-light surface of the third lens, satisfy: 0.1 < |SAG31-SAG32| / CT3 < 1.0.

[0024] According to one embodiment of this application, the axial distance TD between the far-light surface of the first lens and the near-light surface of the third lens, and half of the maximum field of view (Semi-FOV) of the optical system, satisfy: Semi-FOV > 50°; 15.0 mm <TD×tan(Semi-FOV)<40.0mm。

[0025] According to one embodiment of this application, the radius of curvature of the far-light surface of the third lens is less than zero, and the radius of curvature of the near-light surface of the third lens is less than zero.

[0026] The beneficial effects of this application are:

[0027] The optical system provided in this application can reflect light in a certain polarization direction and transmit light orthogonal to that polarization direction using a reflective polarizing element; a quarter-wave plate can add phase delay to polarized light, thereby changing the polarization state of the light; a partial reflective layer can achieve reflection and transmission; combined with the first, second and third lenses, the optical system can achieve folding, shorten the length of the optical system, and improve the poor edge field-of-view imaging quality of the two-lens system by using three lenses. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the optical system of this application;

[0030] Figure 2 This is a partially enlarged schematic diagram of the optical system of this application;

[0031] Figure 3 This is a schematic diagram of the lens group structure of Embodiment 1 of the optical system of this application;

[0032] Figures 4a to 4dThese are the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illumination curve of the optical system embodiment 1 of this application, respectively.

[0033] Figure 5 This is a schematic diagram of the lens group structure of Embodiment 2 of the optical system of this application;

[0034] Figures 6a to 6d These are the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illumination curve of the optical system embodiment 2 of this application, respectively.

[0035] Figure 7 This is a schematic diagram of the lens group structure of embodiment 3 of the optical system of this application;

[0036] Figures 8a to 8d These are the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illumination curve of the optical system embodiment 3 of this application, respectively.

[0037] Figure 9 This is a schematic diagram of the lens group structure of embodiment 4 of the optical system of this application;

[0038] Figures 10a to 10d These are the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illumination curve of the optical system embodiment 4 of this application, respectively.

[0039] Figure 11 This is a schematic diagram of the lens group structure of embodiment 5 of the optical system of this application;

[0040] Figures 12a to 12d These are the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illumination curve of the optical system embodiment 5 of this application, respectively.

[0041] Figure 13 This is a schematic diagram of the lens group structure of embodiment 6 of the optical system of this application;

[0042] Figures 14a to 14d These are the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illumination curve of the optical system embodiment 6 of this application, respectively.

[0043] Figure 15 This is a schematic diagram of the lens group structure of embodiment 7 of the optical system of this application;

[0044] Figures 16a to 16d These are the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illumination curve of the optical system embodiment 7 of this application, respectively. Detailed Implementation

[0045] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0046] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0047] 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.

[0048] 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.

[0049] In the description of this application, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region. If the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens furthest from the display is called the far-light surface of the lens, and the surface of each lens closest to the display is called the near-light surface of the lens. The surface shape in the paraxial region can be determined according to the judgment method commonly known in the art, using the R value (R refers to the radius of curvature of the paraxial region, usually the R value in the lens database of optical software) to determine concavity or convexity. For the far-light side, when the R value is positive, it is determined to be convex, and when the R value is negative, it is determined to be concave; for the near-light side, when the R value is positive, it is determined to be concave, and when the R value is negative, it is determined to be convex.

[0050] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill 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 that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0051] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments may be combined with each other. The features, principles and other aspects of this application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0052] Exemplary embodiments

[0053] Reference Figure 1 and Figure 2 As shown, the optical system of the exemplary embodiment of this application includes: a first lens, a reflective polarizing element, a quarter-wave plate, a second lens, a third lens, and a display; wherein, the first lens to the third lens are arranged in sequence along the optical axis from a position far from the display to a position close to the display; the reflective polarizing element and the quarter-wave plate are arranged between the first lens and the second lens; each of the first lens to the third lens has at least one far-light surface far from the display and at least one near-light surface close to the display; a partial reflection layer is provided on at least one of the far-light surfaces or near-light surfaces of the first lens to the third lens. Among them, the reflective polarizing element can reflect light of a certain polarization direction and transmit light orthogonal to this polarization direction at the same time; the quarter-wave plate can add a phase delay to the polarized light, thereby changing the polarization state of the light; the partial reflection layer can achieve reflection and transmission; combined with the first, second and third lenses, the system optical path can be folded back, shortening the length of the optical system device, and at the same time improving the problem of poor imaging quality of the edge field of view of the two-lens system by using three lenses.

[0054] In the exemplary embodiment of this application, the effective focal length f of the optical system and the combined focal length F12 of the first lens, the reflective polarizing element, the quarter-wave plate and the second lens satisfy: 0.5 < f / F12 < 1.5; by controlling the ratio of the focal length of the optical system to the combined focal length of the first lens, the reflective polarizing element, the quarter-wave plate and the second lens, the optical power of the system is reasonably distributed. More specifically, the effective focal length f of the optical system and the combined focal length F12 of the first lens, the reflective polarizing element, the quarter-wave plate and the second lens satisfy: 0.90 < f / F12 < 1.10.

[0055] In an exemplary embodiment of the present application, the effective focal length f of the optical system and the focal length f3 of the third lens satisfy: -20.0 < f3 / f < 30.0. By controlling the focal length of the optical system and the focal length of the third lens and reasonably distributing and adjusting the proportion of the optical power, it is beneficial to ensure the image quality. More specifically, the effective focal length f of the optical system and the focal length f3 of the third lens satisfy: -11.0 < f3 / f < 28.0.

[0056] In this exemplary embodiment, the on-axis distance TD from the far-light surface of the first lens to the near-light surface of the third lens and the effective focal length f of the optical system satisfy: 0.3 < TD / f < 1.0. By controlling the ratio of the on-axis distance from the far-light surface of the first lens to the near-light surface of the third lens to the effective focal length of the system within a reasonable range, a compact design of the optical system can be achieved. More specifically, the on-axis distance TD from the far-light surface of the first lens to the near-light surface of the third lens and the effective focal length f of the optical system satisfy: 0.4 < TD / f < 0.8.

[0057] In this exemplary embodiment, the refractive index N1 of the first lens, the refractive index N2 of the second lens, and the refractive index N3 of the third lens satisfy: 1.5 < (N1 + N2) / N3 < 2.1. By controlling the ratio of the sum of the refractive indices of the first and second lenses to the refractive index of the third lens within a reasonable range, the distribution of the optical power of the optical system can be controlled, which is beneficial to optimizing the light path of the system.

[0058] In this exemplary embodiment, the reflective polarizing element includes at least one far-light surface away from the display and at least one near-light surface close to the display; the quarter-wave plate includes at least one far-light surface away from the display and at least one near-light surface close to the display; wherein, the near-light surface of the reflective polarizing element is at least partially in contact with the far-light surface of the quarter-wave plate. By using the thin-film composite technology to composite the near-light surface of the reflective polarizing element and the far-light surface of the quarter-wave plate into a whole, the thin-film attachment process can be simplified.

[0059] In this exemplary embodiment, the reflective polarizing element includes at least one far-light surface away from the display and at least one near-light surface close to the display; the far-light surface of the reflective polarizing element is at least partially in contact with the near-light surface of the first lens. By placing the reflective polarizing element and the quarter-wave plate between the first lens and the second lens, and utilizing the phase addition function of the quarter-wave plate for polarized light and the beam-splitting function of the reflective polarizing element, the folding effect of the imaging light path can be achieved; the far-light surface of the reflective polarizing element is attached to the near-light surface of the first lens by an attachment method.

[0060] In the present exemplary embodiment, the quarter-wave plate includes at least one far-light surface away from the display and at least one near-light surface close to the display; the near-light surface of the quarter-wave plate is at least partially in contact with the far-light surface of the second lens. The reflective polarizing element and the quarter-wave plate are disposed between the first lens and the second lens. By utilizing the function of adding a polarization light phase by the quarter-wave plate and the beam splitting function of the reflective polarizing element, the folding effect of the imaging optical path is achieved; the near-light surface of the quarter-wave plate is attached to the far-light surface of the second lens by an attachment method.

[0061] In the present exemplary embodiment, the dispersion coefficient V1 of the first lens, the dispersion coefficient V2 of the second lens, the central thickness CT1 of the first lens on the optical axis, the central thickness CT2 of the second lens on the optical axis, and the spacing distance T12 between the near-light surface of the first lens and the far-light surface of the second lens on the optical axis satisfy: 30.0 < (V1×CT1 + V2×CT2) / (CT1 + T12 + CT2) < 60.0. By controlling the parameter relationship between the dispersion coefficients of the first and second lenses and the central thicknesses of the lenses and the spacing between the lenses within a reasonable range, it is beneficial to reduce the overall chromatic aberration of the system and improve the imaging quality of the system. More specifically, the dispersion coefficient V1 of the first lens, the dispersion coefficient V2 of the second lens, the central thickness CT1 of the first lens on the optical axis, the central thickness CT2 of the second lens on the optical axis, and the spacing distance T12 between the near-light surface of the first lens and the far-light surface of the second lens on the optical axis satisfy: 41.0 < (V1×CT1 + V2×CT2) / (CT1 + T12 + CT2) < 58.0.

[0062] In the present exemplary embodiment, the effective focal length f of the optical system and the spacing distance FL between the near-light surface of the third lens and the display on the optical axis satisfy: 1.0 < f / FL < 10.0. By controlling the ratio of the effective focal length of the optical system to the spacing distance between the near-light surface of the third lens and the display on the optical axis within a reasonable range, the incident height of the light rays to the display surface can be restricted, which is beneficial to reducing the screen size. More specifically, the effective focal length f of the optical system and the spacing distance FL between the near-light surface of the third lens and the display on the optical axis satisfy: 1.7 < f / FL < 4.7.

[0063] In the present exemplary embodiment, the dispersion coefficient V3 of the third lens and the refractive index N3 of the third lens satisfy: 10.0 < V3 / N3 < 50.0. By controlling the ratio of the dispersion coefficient of the third lens to the refractive index within a reasonable range, it is beneficial to select more conventional and more reasonable performance optical materials. More specifically, the dispersion coefficient V3 of the third lens and the refractive index N3 of the third lens satisfy: 11.0 < V3 / N3 < 41.0.

[0064] In the present exemplary embodiment, the radius of curvature R5 of the third lens' far - light surface and the radius of curvature R6 of the third lens' near - light surface satisfy: - 1.0 < (R5 - R6) / (R5 + R6) < 1.0. By controlling the radius of curvature of the third lens, the optical power value of the third lens can be controlled, making the light path more optimal, which helps to improve the image quality of the system and the relative illumination of the system; at the same time, it can keep the third lens with good processing manufacturability and enhance the practicability of the lens group. More specifically, the radius of curvature R5 of the third lens' far - light surface and the radius of curvature R6 of the third lens' near - light surface satisfy: - 0.8 < (R5 - R6) / (R5 + R6) < 0, 0 < (R5 - R6) / (R5 + R6) < 0.5.

[0065] In the present exemplary embodiment, the spacing distance T23 between the second lens' near - light surface and the third lens' far - light surface on the optical axis and the central thickness CT3 of the third lens on the optical axis satisfy: 0 < T23 / CT3 < 1.5. Controlling the air thickness between the second and third lenses and the central thickness of the third lens is beneficial to the compact design of the system; at the same time, it is beneficial to control the layout of the third lens, reasonably allocate the tolerances in the assembly process of the third lens, and effectively improve the manufacturability of the lens. More specifically, the spacing distance T23 between the second lens' near - light surface and the third lens' far - light surface on the optical axis and the central thickness CT3 of the third lens on the optical axis satisfy: 0.3 < T23 / CT3 < 1.2.

[0066] In the present exemplary embodiment, the above - mentioned partial reflection layer is coated on the near - light surface or the far - light surface of the third lens. Coating the partial reflection layer on the near - light surface or the far - light surface of the third lens, and using the transmission and reflection characteristics of the partial reflection layer to achieve the folding effect of the imaging light path.

[0067] In the present exemplary embodiment, the refractive index NRP of the reflective polarizing element, the refractive index NQWP of the quarter - wave plate, the refractive index N1 of the first lens, and the refractive index N2 of the second lens satisfy: 0.8 < (NRP + NQWP) / (N1 + N2) < 1.2. By controlling the ratio of the refractive indices of the reflective polarizing element and the quarter - wave plate to the refractive indices of the first lens and the second lens within a reasonable range, the refractive indices of the reflective polarizing element and the quarter - wave plate are matched with the refractive indices of the lenses, avoiding additional aberrations introduced by the reflective polarizing element and the quarter - wave plate.

[0068] In the present exemplary embodiment, the radius of curvature R1 of the first lens' far - light surface and the radius of curvature R4 of the second lens' near - light surface satisfy: 0.2 < (R1 + R4) / (R1 - R4) < 1.2. By controlling the relationship between the radius of curvature of the first lens' far - light surface and the radius of curvature of the second lens' near - light surface, the CRA of the outer field of view can be effectively controlled, making the CRA within a smaller range.

[0069] In this exemplary embodiment, the dispersion coefficient VRP of the reflective polarizing element, the dispersion coefficient VQWP of the quarter-wave plate, the center thickness CTR of the reflective polarizing element on the optical axis, the center thickness CTQWP of the quarter-wave plate on the optical axis, and the combined focal length F12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens satisfy: 1.2 < (VRP + VQWP) × (CTR + CTQWP) / F12 < 2.0. By controlling the ratio of the dispersion coefficients and center thicknesses of the reflective polarizing element and the quarter-wave plate to the combined focal length within a reasonable range, the amount of dispersion introduced by the reflective polarizing element and the quarter-wave plate can be controlled, which is beneficial for system chromatic aberration correction. More specifically, the dispersion coefficient VRP of the reflective polarizing element, the dispersion coefficient VQWP of the quarter-wave plate, the center thickness CTR of the reflective polarizing element on the optical axis, the center thickness CTQWP of the quarter-wave plate on the optical axis, and the combined focal length F12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens satisfy: 1.4 < (VRP + VQWP) × (CTR + CTQWP) / F12 < 1.7.

[0070] In this exemplary embodiment, the maximum effective radius DT31 of the far-light surface of the third lens and the maximum effective radius DT32 of the near-light surface of the third lens satisfy: -0.5 < (DT31 + DT32) / f3 < 0.5. By controlling the ratio of the effective aperture to the focal length of the third lens within a reasonable range, the third lens has a more reasonable optical power, improving the compactness of the system. More specifically, the maximum effective radius DT31 of the far-light surface of the third lens and the maximum effective radius DT32 of the near-light surface of the third lens satisfy: -0.2 < (DT31 + DT32) / f3 < 0.3.

[0071] In this exemplary embodiment, the axial distance SAG31 between the intersection of the far-light surface and the optical axis of the third lens and the vertex of the effective radius of the far-light surface of the third lens, and the axial distance SAG32 between the intersection of the near-light surface and the optical axis of the third lens and the vertex of the effective radius of the near-light surface of the third lens, satisfy: 0.1 < |SAG31 - SAG32| / CT3 < 1.0. By controlling the relationship between the height of the two surfaces of the third lens and the center thickness, the shape of the third lens is constrained, which helps to reduce the difficulty of the lens forming process, control the light direction, optimize the ghosting produced by the third lens, and improve the imaging quality of the system. More specifically, the axial distance SAG31 between the intersection of the far-light surface and the optical axis of the third lens and the vertex of the effective radius of the far-light surface of the third lens, and the axial distance SAG32 between the intersection of the near-light surface and the optical axis of the third lens and the vertex of the effective radius of the near-light surface of the third lens, satisfy: 0.3 < |SAG31 - SAG32| / CT3 < 0.7.

[0072] In the present exemplary embodiment, the on-axis distance TD from the far-light surface of the first lens to the near-light surface of the third lens and half of the maximum field angle Semi-FOV of the optical system satisfy: Semi-FOV > 50°; 15.0 mm < TD × tan(Semi-FOV) < 40.0 mm. By controlling the parameter relationship between the FOV and the body length, it is possible to further constrain the system length and height while ensuring the viewing angle. More specifically, the on-axis distance TD from the far-light surface of the first lens to the near-light surface of the third lens and half of the maximum field angle Semi-FOV of the optical system satisfy: Semi-FOV > 52.0°; 17.0 mm < TD × tan(Semi-FOV) < 29.0 mm.

[0073] In the present exemplary embodiment, the curvature radius value of the far-light surface of the third lens is less than zero, and the curvature radius value of the near-light surface of the third lens is less than zero. The third lens is in the shape of a meniscus lens with the convex surface facing the display, which can reduce the system focal length and increase the system numerical aperture without introducing significant spherical aberration, thereby enhancing the light collection ability of the system.

[0074] In the present exemplary embodiment, the object side and the image side of any one of the first lens E1 to the third lens E3 are aspherical surfaces. The surface profile x of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0075]

[0076] where x is the sagitta distance from the vertex of the aspherical surface when the aspherical surface is along the optical axis at a position with a height of h; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the curvature radius R in Table 1); k is the conic coefficient; and Ai is the correction coefficient of the i-th order of the aspherical surface.

[0077] In the present exemplary embodiment, the above optical system may further include an aperture stop. The aperture stop can be set at an appropriate position as needed. For example, the aperture stop can be set between the object side and the first lens. Optionally, the above optical system may further include a filter for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging surface.

[0078] The optical system according to the above embodiment of the present application may use multiple lenses, such as the three lenses described above. By reasonably distributing the optical power, surface profile, central thickness of each lens, and on-axis spacing between each lens, etc., the optical system has a larger field of view range and ensures the compactness of the optical system.

[0079] In an exemplary embodiment, at least one of the far-light and near-light surfaces of each lens is aspherical; that is, at least one surface from the far-light surface of the first lens to the near-light surface of the third lens is aspherical. The characteristic of an aspherical lens is that its curvature changes continuously from the lens center to the lens periphery. Unlike a spherical lens, which has a constant curvature from the lens center to the lens periphery, an aspherical lens has better curvature radius characteristics, offering advantages in improving distortion aberrations and astigmatism. By using an aspherical lens, aberrations occurring during imaging can be eliminated as much as possible, thereby improving image quality. Optionally, at least one of the far-light and near-light surfaces of each of the first, second, and third lenses is aspherical. Optionally, both the far-light and near-light surfaces of each of the first, second, and third lenses are aspherical.

[0080] However, those skilled in the art will understand that the number of lenses constituting the optical system can be changed without departing from the technical solutions claimed in this application to obtain the various results and advantages described in this specification. For example, although three lenses are described as an example in the embodiments, the optical system is not limited to including three lenses, and may include other numbers of lenses if necessary.

[0081] Specific embodiments of the optical system applicable to the above embodiments are further described below with reference to the accompanying drawings. Specific Implementation Example 1

[0083] Figure 3 This is a schematic diagram of the lens group structure of embodiment 1 of the optical system of this application. The optical system includes: aperture stop STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, third lens E3, and display.

[0084] The first lens E1 to the third lens E3 are arranged sequentially along the optical axis from the position furthest from the display to the position closest to the display. A reflective polarizing element RP and a quarter-wave plate QWP are sequentially arranged between the first lens E1 and the second lens E2. The near-light surface of the second lens E2 has a partially reflective layer. Each of the first to third lenses has a far-light surface far from the display and a near-light surface close to the display; the far-light surface of the third lens has a partially reflective layer. The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display). After passing through the third lens, the second lens, and the quarter-wave plate, the light becomes linearly polarized. It is reflected after reaching the near-light surface of the reflective polarizing element, then passes through the quarter-wave plate and the second lens before reaching the far-light surface of the third lens. There, it is reflected by the partially reflective layer on the far-light surface of the third lens, and then passes through the second lens, the quarter-wave plate, the reflective polarizing element, and the first lens before entering the human eye.

[0085] Table 1 shows the basic parameters of the optical system in Example 1, where the units for radius of curvature and thickness are millimeters (mm).

[0086]

[0087] Table 1

[0088] As shown in Table 2, in Example 1, the total effective focal length of the optical system is f = 28.44 mm, and the Semi-FOV (half of the maximum field of view) of the optical system is 53.0°.

[0089]

[0090] Table 2

[0091] The optical system in Example 1 satisfies:

[0092] f / F12 = 0.97, where f is the effective focal length of the optical system and F12 is the combined focal length of the reflective polarizing element, the quarter-wave plate, and the second lens.

[0093] f3 / f = 7.85, where f is the effective focal length of the optical system and f3 is the focal length of the third lens.

[0094] TD / f = 0.60, where TD is the on-axis distance from the far-light surface of the first lens to the near-light surface of the third lens, and f is the effective focal length of the optical system.

[0095] (N1+N2) / N3=2.00, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, and N3 is the refractive index of the third lens.

[0096] (V1×CT1+V2×CT2) / (CT1+T12+CT2)=55.56, where V1 is the dispersion coefficient of the first lens, V2 is the dispersion coefficient of the second lens, CT1 is the center thickness of the first lens on the optical axis, CT2 is the center thickness of the second lens on the optical axis, and T12 is the distance between the near-light surface of the first lens and the far-light surface of the second lens on the optical axis.

[0097] f / FL = 2.71, where f is the effective focal length of the optical system and FL is the distance between the near-light surface of the third lens and the display on the optical axis.

[0098] V3 / N3 = 40.54, where V3 is the dispersion coefficient of the third lens and N3 is the refractive index of the third lens.

[0099] (R5-R6) / (R5+R6)=0.26, where R5 is the radius of curvature of the far-light surface of the third lens and R6 is the radius of curvature of the near-light surface of the third lens.

[0100] T23 / CT3=0.51, where T23 is the distance between the near-light surface of the second lens and the far-light surface of the third lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis.

[0101] (NRP+NQWP) / (N1+N2)=1.01, where NRP is the refractive index of the reflective polarizing element, NQWP is the refractive index of the quarter-wave plate, N1 is the refractive index of the first lens, and N2 is the refractive index of the second lens.

[0102] (R1+R4) / (R1-R4)=0.72, where R1 is the radius of curvature of the far-light surface of the first lens and R4 is the radius of curvature of the near-light surface of the second lens.

[0103] (VRP+VQWP)×(CTR+CTQWP) / F12=1.55, where VRP is the dispersion coefficient of the reflective polarizing element, VQWP is the dispersion coefficient of the quarter-wave plate, CTR is the center thickness of the reflective polarizing element on the optical axis, CTQWP is the center thickness of the quarter-wave plate on the optical axis, and F12 is the combined focal length of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens.

[0104] (DT31+DT32) / f3=0.24, where DT31 is the maximum effective radius of the far-light surface of the third lens and DT32 is the maximum effective radius of the near-light surface of the third lens.

[0105] |SAG31-SAG32| / CT3=0.67, where SAG31 is the on-axis distance between the intersection of the far-light surface of the third lens and the optical axis and the vertex of the effective radius of the far-light surface of the third lens, and SAG32 is the on-axis distance between the intersection of the near-light surface of the third lens and the optical axis and the vertex of the effective radius of the near-light surface of the third lens.

[0106] TD×tan(Semi-FOV)=22.60, where TD is the on-axis distance from the far-light surface of the first lens to the near-light surface of the third lens, and Semi-FOV is half of the maximum field of view of the optical system.

[0107] In Example 1, the far-light and near-light surfaces of any one of the lenses, from the first lens E1 to the third lens E3, are aspherical. Table 3 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical surfaces S1, S2, S5, S6, S7, and S8 in Example 1. 10 .

[0108] Face number A4 A6 A8 A10 S1 -1.0994E+00 2.9372E-01 -6.4048E-02 2.5441E-03 S2 -1.2020E+00 1.5756E-01 -5.5852E-03 -3.6347E-03 S5 -2.5936E-01 -5.3050E-02 1.2231E-02 6.8903E-03 S6 5.1420E-01 2.7388E-02 1.2765E-02 -3.0047E-02 S7 -1.0586E+00 1.3264E-01 -2.0090E-02 9.1898E-03 S8 1.7084E+00 -3.4842E-01 9.5043E-03 4.9348E-02

[0109] Table 3

[0110] Figure 4aThe on-axis chromatic aberration curve of the optical system of Embodiment 1 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 4b 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 4c The distortion curves of the optical system of Example 1 are shown, representing the magnitude of distortion under different viewing angles. Figure 4d The relative illumination curves of the optical system of Example 1 are shown, representing the relative illumination corresponding to different field angles on the imaging plane. According to... Figures 4a to 4d As shown, the optical system given in Example 1 can achieve good imaging quality. Specific Implementation Example 2

[0112] Figure 5 This is a schematic diagram of the lens group structure of embodiment 2 of the optical system of this application. The optical system includes: aperture stop STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, third lens E3, and display.

[0113] The first lens E1 to the third lens E3 are arranged sequentially along the optical axis from the position furthest from the display to the position closest to the display. A reflective polarizing element RP and a quarter-wave plate QWP are sequentially arranged between the first lens E1 and the second lens E2. The near-light surface of the second lens E2 has a partially reflective layer. Each of the first to third lenses has a far-light surface far from the display and a near-light surface close to the display; the far-light surface of the third lens has a partially reflective layer. The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display). After passing through the third lens, the second lens, and the quarter-wave plate, the light becomes linearly polarized. It is reflected after reaching the near-light surface of the reflective polarizing element, then passes through the quarter-wave plate and the second lens before reaching the far-light surface of the third lens. There, it is reflected by the partially reflective layer on the far-light surface of the third lens, and then passes through the second lens, the quarter-wave plate, the reflective polarizing element, and the first lens before entering the human eye.

[0114] Table 4 shows the basic parameters of the optical system in Example 2, where the units for radius of curvature and thickness are millimeters (mm).

[0115]

[0116] Table 4

[0117] As shown in Table 5, in Example 2, the total effective focal length of the optical system is f = 26.91 mm, and the Semi-FOV (half of the maximum field of view) of the optical system is 53.0°.

[0118]

[0119]

[0120] Table 5

[0121] The optical system in Example 2 satisfies:

[0122] f / F12 = 0.98, where f is the effective focal length of the optical system and F12 is the combined focal length of the reflective polarizing element, the quarter-wave plate, and the second lens.

[0123] f3 / f = 9.91, where f is the effective focal length of the optical system and f3 is the focal length of the third lens.

[0124] TD / f = 0.67, where TD is the on-axis distance from the far-light surface of the first lens to the near-light surface of the third lens, and f is the effective focal length of the optical system.

[0125] (N1+N2) / N3=2.00, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, and N3 is the refractive index of the third lens.

[0126] (V1×CT1+V2×CT2) / (CT1+T12+CT2)=55.89, where V1 is the dispersion coefficient of the first lens, V2 is the dispersion coefficient of the second lens, CT1 is the center thickness of the first lens on the optical axis, CT2 is the center thickness of the second lens on the optical axis, and T12 is the distance between the near-light surface of the first lens and the far-light surface of the second lens on the optical axis.

[0127] f / FL = 4.06, where f is the effective focal length of the optical system and FL is the distance between the near-light surface of the third lens and the display on the optical axis.

[0128] V3 / N3 = 40.54, where V3 is the dispersion coefficient of the third lens and N3 is the refractive index of the third lens.

[0129] (R5-R6) / (R5+R6)=0.19, where R5 is the radius of curvature of the far-light surface of the third lens and R6 is the radius of curvature of the near-light surface of the third lens.

[0130] T23 / CT3 = 1.07, where T23 is the distance between the near-light surface of the second lens and the far-light surface of the third lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis.

[0131] (NRP+NQWP) / (N1+N2)=1.01, where NRP is the refractive index of the reflective polarizing element, NQWP is the refractive index of the quarter-wave plate, N1 is the refractive index of the first lens, and N2 is the refractive index of the second lens.

[0132] (R1+R4) / (R1-R4)=0.88, where R1 is the radius of curvature of the far-light surface of the first lens and R4 is the radius of curvature of the near-light surface of the second lens.

[0133] (VRP+VQWP)×(CTR+CTQWP) / F12=1.67, where VRP is the dispersion coefficient of the reflective polarizing element, VQWP is the dispersion coefficient of the quarter-wave plate, CTR is the center thickness of the reflective polarizing element on the optical axis, CTQWP is the center thickness of the quarter-wave plate on the optical axis, and F12 is the combined focal length of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens.

[0134] (DT31+DT32) / f3=0.19, where DT31 is the maximum effective radius of the far-light surface of the third lens and DT32 is the maximum effective radius of the near-light surface of the third lens.

[0135] |SAG31-SAG32| / CT3=0.53, where SAG31 is the on-axis distance between the intersection of the far-light surface of the third lens and the optical axis and the vertex of the effective radius of the far-light surface of the third lens, and SAG32 is the on-axis distance between the intersection of the near-light surface of the third lens and the optical axis and the vertex of the effective radius of the near-light surface of the third lens.

[0136] TD×tan(Semi-FOV)=23.97, where TD is the on-axis distance from the far-light surface of the first lens to the near-light surface of the third lens, and Semi-FOV is half of the maximum field of view of the optical system.

[0137] In Example 2, the far-light and near-light surfaces of any one of the lenses, from the first lens E1 to the third lens E3, are aspherical. Table 6 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical surfaces S1, S2, S5, S6, S7, and S8 in Example 2. 10 .

[0138] Face number A4 A6 A8 A10 S1 -9.8248E-01 3.2443E-01 -7.7071E-02 6.6658E-03 S2 -1.2685E+00 1.7097E-01 -1.3451E-02 -1.0580E-03 S5 -1.6244E-01 -1.1017E-01 3.7188E-02 3.3492E-03 S6 1.0063E+00 -4.1803E-02 3.6527E-02 -3.3953E-02 S7 -1.0511E+00 1.0926E-01 -1.9106E-02 1.1287E-02 S8 2.3931E+00 -7.3341E-01 8.2449E-02 6.5034E-02

[0139] Table 6

[0140] Figure 6a The on-axis chromatic aberration curve of the optical system of Embodiment 2 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 6b 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 6c The distortion curves of the optical system of Example 2 are shown, representing the magnitude of distortion under different viewing angles. Figure 6d The relative illumination curves of the optical system in Example 2 are shown, representing the relative illumination corresponding to different field angles on the imaging plane. According to... Figures 6a to 6dAs shown, the optical system given in Example 2 can achieve good imaging quality. Specific Implementation Example 3

[0142] Figure 7 This is a schematic diagram of the lens group structure of embodiment 3 of the optical system of this application. The optical system includes: aperture stop STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, third lens E3, and display.

[0143] The first lens E1 to the third lens E3 are arranged sequentially along the optical axis from the position furthest from the display to the position closest to the display. A reflective polarizing element RP and a quarter-wave plate QWP are sequentially arranged between the first lens E1 and the second lens E2. The near-light surface of the second lens E2 has a partially reflective layer. Each of the first to third lenses has a far-light surface far from the display and a near-light surface close to the display; the far-light surface of the third lens has a partially reflective layer. The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display). After passing through the third lens, the second lens, and the quarter-wave plate, the light becomes linearly polarized. It is reflected after reaching the near-light surface of the reflective polarizing element, then passes through the quarter-wave plate and the second lens before reaching the far-light surface of the third lens. There, it is reflected by the partially reflective layer on the far-light surface of the third lens, and then passes through the second lens, the quarter-wave plate, the reflective polarizing element, and the first lens before entering the human eye.

[0144] Table 7 shows the basic parameters of the optical system in Example 3, where the units for radius of curvature and thickness are millimeters (mm).

[0145]

[0146]

[0147] As shown in Table 8, in Example 3, the total effective focal length of the optical system is f = 27.19 mm, and the Semi-FOV (half of the maximum field of view) of the optical system is 53.0°.

[0148]

[0149] Table 8

[0150] The optical system in Example 3 satisfies:

[0151] f / F12 = 0.99, where f is the effective focal length of the optical system and F12 is the combined focal length of the reflective polarizing element, the quarter-wave plate, and the second lens.

[0152] f3 / f = 10.86, where f is the effective focal length of the optical system and f3 is the focal length of the third lens.

[0153] TD / f = 0.73, where TD is the on-axis distance from the far-light surface of the first lens to the near-light surface of the third lens, and f is the effective focal length of the optical system.

[0154] (N1+N2) / N3=2.00, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, and N3 is the refractive index of the third lens.

[0155] (V1×CT1+V2×CT2) / (CT1+T12+CT2)=56.88, where V1 is the dispersion coefficient of the first lens, V2 is the dispersion coefficient of the second lens, CT1 is the center thickness of the first lens on the optical axis, CT2 is the center thickness of the second lens on the optical axis, and T12 is the distance between the near-light surface of the first lens and the far-light surface of the second lens on the optical axis.

[0156] f / FL = 4.67, where f is the effective focal length of the optical system and FL is the distance between the near-light surface of the third lens and the display on the optical axis.

[0157] V3 / N3 = 40.54, where V3 is the dispersion coefficient of the third lens and N3 is the refractive index of the third lens.

[0158] (R5-R6) / (R5+R6)=0.17, where R5 is the radius of curvature of the far-light surface of the third lens and R6 is the radius of curvature of the near-light surface of the third lens.

[0159] T23 / CT3 = 1.01, where T23 is the distance between the near-light surface of the second lens and the far-light surface of the third lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis.

[0160] (NRP+NQWP) / (N1+N2)=1.01, where NRP is the refractive index of the reflective polarizing element, NQWP is the refractive index of the quarter-wave plate, N1 is the refractive index of the first lens, and N2 is the refractive index of the second lens.

[0161] (R1+R4) / (R1-R4)=0.95, where R1 is the radius of curvature of the far-light surface of the first lens and R4 is the radius of curvature of the near-light surface of the second lens.

[0162] (VRP+VQWP)×(CTR+CTQWP) / F12=1.66, where VRP is the dispersion coefficient of the reflective polarizing element, VQWP is the dispersion coefficient of the quarter-wave plate, CTR is the center thickness of the reflective polarizing element on the optical axis, CTQWP is the center thickness of the quarter-wave plate on the optical axis, and F12 is the combined focal length of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens.

[0163] (DT31+DT32) / f3=0.17, where DT31 is the maximum effective radius of the far-light surface of the third lens and DT32 is the maximum effective radius of the near-light surface of the third lens.

[0164] |SAG31-SAG32| / CT3=0.39, where SAG31 is the on-axis distance between the intersection of the far-light surface of the third lens and the optical axis and the vertex of the effective radius of the far-light surface of the third lens, and SAG32 is the on-axis distance between the intersection of the near-light surface of the third lens and the optical axis and the vertex of the effective radius of the near-light surface of the third lens.

[0165] TD×tan(Semi-FOV)=26.23, where TD is the on-axis distance from the far-light surface of the first lens to the near-light surface of the third lens, and Semi-FOV is half of the maximum field of view of the optical system.

[0166] In Example 3, the far-light and near-light surfaces of any one of the lenses, from the first lens E1 to the third lens E3, are aspherical. Table 9 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical surfaces S1, S2, S5, S6, S7, and S8 in Example 3. 10 .

[0167] Face number A4 A6 A8 A10 S1 -7.4456E-01 2.8602E-01 -7.3443E-02 7.1720E-03 S2 -1.2860E+00 1.6900E-01 -1.2544E-02 -1.0530E-03 S5 -1.3744E-01 -1.1137E-01 4.2719E-02 1.8823E-03 S6 1.2102E+00 -9.4917E-02 5.0514E-02 -3.3141E-02 S7 -1.0035E+00 9.5119E-02 -1.7819E-02 1.1013E-02 S8 2.1938E+00 -5.9126E-01 5.6022E-02 6.4533E-02

[0168] Table 9

[0169] Figure 8a The on-axis chromatic aberration curve of the optical system of Embodiment 3 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 8b 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 8c The distortion curves of the optical system of Example 3 are shown, representing the magnitude of distortion under different viewing angles. Figure 8d The relative illumination curves of the optical system in Example 3 are shown, representing the relative illumination corresponding to different field angles on the imaging plane. According to... Figures 8a to 8d As shown, the optical system given in Example 3 can achieve good imaging quality. Specific Implementation Example 4

[0171] Figure 9 This is a schematic diagram of the lens group structure of embodiment 4 of the optical system of this application. The optical system includes: aperture stop STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, third lens E3, and display.

[0172] The first lens E1 to the third lens E3 are arranged sequentially along the optical axis from the position furthest from the display to the position closest to the display. A reflective polarizing element RP and a quarter-wave plate QWP are sequentially arranged between the first lens E1 and the second lens E2. The near-light surface of the second lens E2 has a partially reflective layer. Each of the first to third lenses has a far-light surface far from the display and a near-light surface close to the display; the far-light surface of the third lens has a partially reflective layer. The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display). After passing through the third lens, the second lens, and the quarter-wave plate, the light becomes linearly polarized. It is reflected after reaching the near-light surface of the reflective polarizing element, then passes through the quarter-wave plate and the second lens before reaching the far-light surface of the third lens. There, it is reflected by the partially reflective layer on the far-light surface of the third lens, and then passes through the second lens, the quarter-wave plate, the reflective polarizing element, and the first lens before entering the human eye.

[0173] Table 10 shows the basic parameters of the optical system in Example 4, where the units for radius of curvature and thickness are millimeters (mm).

[0174]

[0175] As shown in Table 11, in Example 4, the total effective focal length of the optical system is f = 29.38 mm, and the Semi-FOV (half of the maximum field of view) of the optical system is 53.0°.

[0176]

[0177] Table 11

[0178] The optical system in Example 4 satisfies:

[0179] f / F12 = 1.04, where f is the effective focal length of the optical system and F12 is the combined focal length of the reflective polarizing element, the quarter-wave plate, and the second lens.

[0180] f3 / f = -10.62, where f is the effective focal length of the optical system and f3 is the focal length of the third lens.

[0181] TD / f = 0.73, where TD is the on-axis distance from the far-light surface of the first lens to the near-light surface of the third lens, and f is the effective focal length of the optical system.

[0182] (N1+N2) / N3=1.92, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, and N3 is the refractive index of the third lens.

[0183] (V1×CT1+V2×CT2) / (CT1+T12+CT2)=47.62, where V1 is the dispersion coefficient of the first lens, V2 is the dispersion coefficient of the second lens, CT1 is the center thickness of the first lens on the optical axis, CT2 is the center thickness of the second lens on the optical axis, and T12 is the distance between the near-light surface of the first lens and the far-light surface of the second lens on the optical axis.

[0184] f / FL = 3.56, where f is the effective focal length of the optical system and FL is the distance between the near-light surface of the third lens and the display on the optical axis.

[0185] V3 / N3 = 11.38, where V3 is the dispersion coefficient of the third lens and N3 is the refractive index of the third lens.

[0186] (R5-R6) / (R5+R6)=-0.74, where R5 is the radius of curvature of the far-light surface of the third lens and R6 is the radius of curvature of the near-light surface of the third lens.

[0187] T23 / CT3 = 0.46, where T23 is the distance between the near-light surface of the second lens and the far-light surface of the third lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis.

[0188] (NRP+NQWP) / (N1+N2)=0.93, where NRP is the refractive index of the reflective polarizing element, NQWP is the refractive index of the quarter-wave plate, N1 is the refractive index of the first lens, and N2 is the refractive index of the second lens.

[0189] (R1+R4) / (R1-R4)=0.60, where R1 is the radius of curvature of the far-light surface of the first lens and R4 is the radius of curvature of the near-light surface of the second lens.

[0190] (VRP+VQWP)×(CTR+CTQWP) / F12=1.62, where VRP is the dispersion coefficient of the reflective polarizing element, VQWP is the dispersion coefficient of the quarter-wave plate, CTR is the center thickness of the reflective polarizing element on the optical axis, CTQWP is the center thickness of the quarter-wave plate on the optical axis, and F12 is the combined focal length of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens.

[0191] (DT31+DT32) / f3=-0.18, where DT31 is the maximum effective radius of the far-light surface of the third lens and DT32 is the maximum effective radius of the near-light surface of the third lens.

[0192] |SAG31-SAG32| / CT3=0.51, where SAG31 is the on-axis distance between the intersection of the far-light surface of the third lens and the optical axis and the vertex of the effective radius of the far-light surface of the third lens, and SAG32 is the on-axis distance between the intersection of the near-light surface of the third lens and the optical axis and the vertex of the effective radius of the near-light surface of the third lens.

[0193] TD×tan(Semi-FOV)=28.60, where TD is the on-axis distance from the far-light surface of the first lens to the near-light surface of the third lens, and Semi-FOV is half of the maximum field of view of the optical system.

[0194] In Example 4, the far-light and near-light surfaces of any one of the lenses, from the first lens E1 to the third lens E3, are aspherical. Table 12 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical surfaces S1, S2, S5, S6, S7, and S8 in Example 4. 10 .

[0195] Face number A4 A6 A8 A10 S1 -7.4308E-01 8.5690E-02 3.3031E-03 -7.2672E-04 S2 -5.4282E-01 2.7253E-02 5.1401E-04 1.5730E-04 S5 1.9859E-01 -1.3572E-01 4.1814E-02 -1.1816E-02 S6 2.7273E-01 6.4897E-02 -7.1889E-03 -2.0321E-02 S7 -5.9964E-01 -3.0726E-03 2.0777E-02 4.0479E-03 S8 1.9726E+00 -3.5899E-01 5.5090E-02 -2.0262E-02

[0196] Table 12

[0197] Figure 10a The on-axis chromatic aberration curve of the optical system of Embodiment 4 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 10b 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 10c The distortion curves of the optical system of Example 4 are shown, representing the magnitude of distortion under different viewing angles. Figure 10d The relative illumination curves of the optical system in Example 4 are shown, representing the relative illumination corresponding to different field angles on the imaging plane. According to... Figures 10a to 10d As shown, the optical system given in Example 4 can achieve good imaging quality. Specific Implementation Example 5

[0199] Figure 11 This is a schematic diagram of the lens group structure of embodiment 5 of the optical system of this application. The optical system includes: aperture stop STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, third lens E3, and display.

[0200] The first lens E1 to the third lens E3 are arranged sequentially along the optical axis from the position furthest from the display to the position closest to the display. A reflective polarizing element RP and a quarter-wave plate QWP are sequentially arranged between the first lens E1 and the second lens E2. The near-light surface of the second lens E2 has a partially reflective layer. Each of the first to third lenses has a far-light surface far from the display and a near-light surface close to the display; the far-light surface of the third lens has a partially reflective layer. The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display). After passing through the third lens, the second lens, and the quarter-wave plate, the light becomes linearly polarized. It is reflected after reaching the near-light surface of the reflective polarizing element, then passes through the quarter-wave plate and the second lens before reaching the far-light surface of the third lens. There, it is reflected by the partially reflective layer on the far-light surface of the third lens, and then passes through the second lens, the quarter-wave plate, the reflective polarizing element, and the first lens before entering the human eye.

[0201] Table 13 shows the basic parameters of the optical system in Example 5, where the units for radius of curvature and thickness are millimeters (mm).

[0202]

[0203]

[0204] Table 13

[0205] As shown in Table 14, in Example 5, the total effective focal length of the optical system is f = 29.13 mm, and the Semi-FOV (half of the maximum field of view) of the optical system is 53.0°.

[0206]

[0207] Table 14

[0208] The optical system in Example 5 satisfies:

[0209] f / F12 = 0.96, where f is the effective focal length of the optical system and F12 is the combined focal length of the reflective polarizing element, the quarter-wave plate, and the second lens.

[0210] f3 / f = 7.57, where f is the effective focal length of the optical system and f3 is the focal length of the third lens.

[0211] TD / f = 0.61, where TD is the on-axis distance TD from the far-light surface of the first lens to the near-light surface of the third lens, and f is the effective focal length of the optical system.

[0212] (N1+N2) / N3=2.08, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, and N3 is the refractive index of the third lens.

[0213] (V1×CT1+V2×CT2) / (CT1+T12+CT2)=45.02, where V1 is the dispersion coefficient of the first lens, V2 is the dispersion coefficient of the second lens, CT1 is the center thickness of the first lens on the optical axis, CT2 is the center thickness of the second lens on the optical axis, and T12 is the distance between the near-light surface of the first lens and the far-light surface of the second lens on the optical axis.

[0214] f / FL = 2.43, where f is the effective focal length of the optical system and FL is the distance between the near-light surface of the third lens and the display on the optical axis.

[0215] V3 / N3 = 36.36, where V3 is the dispersion coefficient of the third lens and N3 is the refractive index of the third lens.

[0216] (R5-R6) / (R5+R6)=0.41, where R5 is the radius of curvature of the far-light surface of the third lens and R6 is the radius of curvature of the near-light surface of the third lens.

[0217] T23 / CT3 = 0.75, where T23 is the distance between the near-light surface of the second lens and the far-light surface of the third lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis.

[0218] (NRP+NQWP) / (N1+N2)=0.93, where NRP is the refractive index of the reflective polarizing element, NQWP is the refractive index of the quarter-wave plate, N1 is the refractive index of the first lens, and N2 is the refractive index of the second lens.

[0219] (R1+R4) / (R1-R4)=0.41, where R1 is the radius of curvature of the far-light surface of the first lens and R4 is the radius of curvature of the near-light surface of the second lens.

[0220] (VRP+VQWP)×(CTR+CTQWP) / F12=1.50, where VRP is the dispersion coefficient of the reflective polarizing element, VQWP is the dispersion coefficient of the quarter-wave plate, CTR is the center thickness of the reflective polarizing element on the optical axis, CTQWP is the center thickness of the quarter-wave plate on the optical axis, and F12 is the combined focal length of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens.

[0221] (DT31+DT32) / f3=0.28, where DT31 is the maximum effective radius of the far-light surface of the third lens and DT32 is the maximum effective radius of the near-light surface of the third lens.

[0222] |SAG31-SAG32| / CT3=0.52, where SAG31 is the on-axis distance between the intersection of the far-light surface of the third lens and the optical axis and the vertex of the effective radius of the far-light surface of the third lens, and SAG32 is the on-axis distance between the intersection of the near-light surface of the third lens and the optical axis and the vertex of the effective radius of the near-light surface of the third lens.

[0223] TD×tan(Semi-FOV)=23.66, where TD is the on-axis distance from the far-light surface of the first lens to the near-light surface of the third lens, and Semi-FOV is half of the maximum field of view of the optical system.

[0224] In Example 5, the far-light and near-light surfaces of any one of the lenses, from the first lens E1 to the third lens E3, are aspherical. Table 15 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical surfaces S1, S2, S5, S6, S7, and S8 in Example 5. 10 .

[0225] Face number A4 A6 A8 A10 S1 -9.6694E-01 1.2642E-01 -8.2646E-03 -3.4092E-03 S2 -6.3908E-01 5.8109E-02 -9.3837E-03 4.9653E-04 S5 4.5949E-01 -2.2523E-01 7.4824E-02 -1.2923E-02 S6 7.3398E-01 -8.5395E-02 6.7490E-02 -4.0458E-02 S7 -8.2614E-01 4.7639E-02 -7.8928E-03 1.8637E-02 S8 9.7305E-01 -7.7798E-02 -9.3270E-02 4.8793E-02

[0226] Table 15

[0227] Figure 12a The on-axis chromatic aberration curve of the optical system of Embodiment 5 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 12b 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 12c The distortion curves of the optical system of Example 5 are shown, representing the magnitude of distortion under different viewing angles. Figure 12d The relative illumination curves of the optical system in Example 5 are shown, representing the relative illumination corresponding to different field angles on the imaging plane. According to... Figures 12a to 12d As can be seen from the figure, the optical system given in Example 5 can achieve good imaging quality. Specific Implementation Example 6

[0229] Figure 13 This is a schematic diagram of the lens group structure of embodiment 6 of the optical system of this application. The optical system includes: aperture stop STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, third lens E3, and display.

[0230] The first lens E1 to the third lens E3 are arranged sequentially along the optical axis from the position furthest from the display to the position closest to the display. A reflective polarizing element RP and a quarter-wave plate QWP are sequentially arranged between the first lens E1 and the second lens E2. The near-light surface of the second lens E2 has a partially reflective layer. Each of the first to third lenses has a far-light surface far from the display and a near-light surface close to the display; the far-light surface of the third lens has a partially reflective layer. The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display). After passing through the third lens, the second lens, and the quarter-wave plate, the light becomes linearly polarized. It is reflected after reaching the near-light surface of the reflective polarizing element, then passes through the quarter-wave plate and the second lens before reaching the far-light surface of the third lens. There, it is reflected by the partially reflective layer on the far-light surface of the third lens, and then passes through the second lens, the quarter-wave plate, the reflective polarizing element, and the first lens before entering the human eye.

[0231] Table 16 shows the basic parameters of the optical system in Example 6, where the units for radius of curvature and thickness are millimeters (mm).

[0232]

[0233]

[0234] Table 16

[0235] As shown in Table 17, in Example 6, the total effective focal length of the optical system is f = 26.91 mm, and the Semi-FOV (half of the maximum field of view) of the optical system is 53.0°.

[0236]

[0237] Table 17

[0238] The optical system in Example 6 satisfies:

[0239] f / F12 = 0.98, where f is the effective focal length of the optical system and F12 is the combined focal length of the reflective polarizing element, the quarter-wave plate, and the second lens.

[0240] f3 / f = 10.53, where f is the effective focal length of the optical system and f3 is the focal length of the third lens.

[0241] TD / f = 0.68, where TD is the on-axis distance TD from the far-light surface of the first lens to the near-light surface of the third lens, and f is the effective focal length of the optical system.

[0242] (N1+N2) / N3=2.00, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, and N3 is the refractive index of the third lens.

[0243] (V1×CT1+V2×CT2) / (CT1+T12+CT2)=57.39, where V1 is the dispersion coefficient of the first lens, V2 is the dispersion coefficient of the second lens, CT1 is the center thickness of the first lens on the optical axis, CT2 is the center thickness of the second lens on the optical axis, and T12 is the distance between the near-light surface of the first lens and the far-light surface of the second lens on the optical axis.

[0244] f / FL = 4.03, where f is the effective focal length of the optical system and FL is the distance between the near-light surface of the third lens and the display on the optical axis.

[0245] V3 / N3 = 40.54, where V3 is the dispersion coefficient of the third lens and N3 is the refractive index of the third lens.

[0246] (R5-R6) / (R5+R6)=0.18, where R5 is the radius of curvature of the far-light surface of the third lens and R6 is the radius of curvature of the near-light surface of the third lens.

[0247] T23 / CT3 = 1.18, where T23 is the distance between the near-light surface of the second lens and the far-light surface of the third lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis.

[0248] (NRP+NQWP) / (N1+N2)=1.01, where NRP is the refractive index of the reflective polarizing element, NQWP is the refractive index of the quarter-wave plate, N1 is the refractive index of the first lens, and N2 is the refractive index of the second lens.

[0249] (R1+R4) / (R1-R4)=0.90, where R1 is the radius of curvature of the far-light surface of the first lens and R4 is the radius of curvature of the near-light surface of the second lens.

[0250] (VRP+VQWP)×(CTR+CTQWP) / F12=1.67, where VRP is the dispersion coefficient of the reflective polarizing element, VQWP is the dispersion coefficient of the quarter-wave plate, CTR is the center thickness of the reflective polarizing element on the optical axis, CTQWP is the center thickness of the quarter-wave plate on the optical axis, and F12 is the combined focal length of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens.

[0251] (DT31+DT32) / f3=0.18, where DT31 is the maximum effective radius of the far-light surface of the third lens and DT32 is the maximum effective radius of the near-light surface of the third lens.

[0252] |SAG31-SAG32| / CT3=0.49, where SAG31 is the on-axis distance between the intersection of the far-light surface of the third lens and the optical axis and the vertex of the effective radius of the far-light surface of the third lens, and SAG32 is the on-axis distance between the intersection of the near-light surface of the third lens and the optical axis and the vertex of the effective radius of the near-light surface of the third lens.

[0253] TD×tan(Semi-FOV)=24.26, where TD is the on-axis distance from the far-light surface of the first lens to the near-light surface of the third lens, and Semi-FOV is half of the maximum field of view of the optical system.

[0254] In Example 6, the far-light and near-light surfaces of any one of the lenses, from the first lens E1 to the third lens E3, are aspherical. Table 18 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical surfaces S1, S2, S5, S6, S7, and S8 in Example 6. 10 .

[0255] Face number A4 A6 A8 A10 S1 -9.4864E-01 3.2128E-01 -7.8548E-02 6.8255E-03 S2 -1.2506E+00 1.6814E-01 -1.3178E-02 -1.2647E-03 S5 -1.8240E-01 -1.0187E-01 3.4780E-02 2.7311E-03 S6 9.7782E-01 -3.5264E-02 3.3328E-02 -3.3389E-02 S7 -1.0300E+00 1.0420E-01 -1.8189E-02 1.0607E-02 S8 2.2988E+00 -7.2164E-01 8.3724E-02 6.2963E-02

[0256] Table 18

[0257] Figure 14a The on-axis chromatic aberration curve of the optical system of Embodiment 6 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 14b The astigmatism curves of the optical system of Embodiment 6 are shown, representing the meridional image plane curvature and the sagittal image plane curvature. Figure 14c The distortion curves of the optical system of Example 6 are shown, representing the magnitude of distortion under different viewing angles. Figure 14d The relative illumination curves of the optical system in Example 6 are shown, representing the relative illumination corresponding to different field angles on the imaging plane. According to... Figures 14a to 14d As shown, the optical system given in Example 6 can achieve good imaging quality. Specific Implementation Example 7

[0259] Figure 15 This is a schematic diagram of the lens group structure of embodiment 7 of the optical system of this application. The optical system includes: aperture stop STO, first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, third lens E3, and display.

[0260] The first lens E1 to the third lens E3 are arranged sequentially along the optical axis from the position furthest from the display to the position closest to the display. A reflective polarizing element RP and a quarter-wave plate QWP are sequentially arranged between the first lens E1 and the second lens E2. The near-light surface of the second lens E2 has a partially reflective layer. Each of the first to third lenses has a far-light surface far from the display and a near-light surface close to the display; the near-light surface of the third lens has a partially reflective layer. The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display), which passes through the third lens, the second lens, and the quarter-wave plate, becoming linearly polarized light. After being reflected by the near-light surface of the reflective polarizing element, it passes through the quarter-wave plate, the second lens, and the third lens again, reaching the near-light surface of the third lens. After being reflected by the partially reflective layer on the near-light surface of the third lens, it passes through the third lens, the second lens, the quarter-wave plate, the reflective polarizing element, and the first lens before entering the human eye.

[0261] Table 19 shows the basic parameters of the optical system in Example 7, where the units for radius of curvature and thickness are millimeters (mm).

[0262]

[0263] Table 19

[0264] As shown in Table 20, in Example 7, the total effective focal length of the optical system is f = 29.94 mm, and the Semi-FOV (half of the maximum field of view) of the optical system is 53.0°.

[0265]

[0266] Table 20

[0267] The optical system in Example 7 satisfies:

[0268] f / F12 = 0.98, where f is the effective focal length of the optical system and F12 is the combined focal length of the reflective polarizing element, the quarter-wave plate, and the second lens.

[0269] f3 / f = 27.34, where f is the effective focal length of the optical system and f3 is the focal length of the third lens.

[0270] TD / f = 0.43, where TD is the on-axis distance from the far-light surface of the first lens to the near-light surface of the third lens, and f is the effective focal length of the optical system.

[0271] (N1+N2) / N3=2.08, where N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, and N3 is the refractive index of the third lens.

[0272] (V1×CT1+V2×CT2) / (CT1+T12+CT2)=42.79, where V1 is the dispersion coefficient of the first lens, V2 is the dispersion coefficient of the second lens, CT1 is the center thickness of the first lens on the optical axis, CT2 is the center thickness of the second lens on the optical axis, and T12 is the distance between the near-light surface of the first lens and the far-light surface of the second lens on the optical axis.

[0273] f / FL = 1.77, where f is the effective focal length of the optical system and FL is the distance between the near-light surface of the third lens and the display on the optical axis.

[0274] V3 / N3 = 36.36, where V3 is the dispersion coefficient of the third lens and N3 is the refractive index of the third lens.

[0275] (R5-R6) / (R5+R6)=0.28, where R5 is the radius of curvature of the far-light surface of the third lens and R6 is the radius of curvature of the near-light surface of the third lens.

[0276] T23 / CT3 = 0.39, where T23 is the distance between the near-light surface of the second lens and the far-light surface of the third lens on the optical axis, and CT3 is the center thickness of the third lens on the optical axis.

[0277] (NRP+NQWP) / (N1+N2)=0.93, where NRP is the refractive index of the reflective polarizing element, NQWP is the refractive index of the quarter-wave plate, N1 is the refractive index of the first lens, and N2 is the refractive index of the second lens.

[0278] (R1+R4) / (R1-R4)=0.25, where R1 is the radius of curvature of the far-light surface of the first lens and R4 is the radius of curvature of the near-light surface of the second lens.

[0279] (VRP+VQWP)×(CTR+CTQWP) / F12=1.50, where VRP is the dispersion coefficient of the reflective polarizing element, VQWP is the dispersion coefficient of the quarter-wave plate, CTR is the center thickness of the reflective polarizing element on the optical axis, CTQWP is the center thickness of the quarter-wave plate on the optical axis, and F12 is the combined focal length of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens.

[0280] (DT31+DT32) / f3=0.07, where DT31 is the maximum effective radius of the far-light surface of the third lens and DT32 is the maximum effective radius of the near-light surface of the third lens.

[0281] |SAG31-SAG32| / CT3=0.39, where SAG31 is the on-axis distance between the intersection of the far-light surface of the third lens and the optical axis and the vertex of the effective radius of the far-light surface of the third lens, and SAG32 is the on-axis distance between the intersection of the near-light surface of the third lens and the optical axis and the vertex of the effective radius of the near-light surface of the third lens.

[0282] TD×tan(Semi-FOV)=17.13, where TD is the on-axis distance from the far-light surface of the first lens to the near-light surface of the third lens, and Semi-FOV is half of the maximum field of view of the optical system.

[0283] In Example 7, the far-light and near-light surfaces of any one of the lenses, from the first lens E1 to the third lens E3, are aspherical. Table 21 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical surfaces S1, S2, S5, S6, S7, and S8 in Example 7. 10 .

[0284] Face number A4 A6 A8 A10 S1 -1.1770E+00 1.4825E-01 -9.9607E-03 8.1529E-04 S2 -9.2729E-01 1.0426E-01 -1.4971E-03 -8.0794E-04 S5 8.8377E-01 -2.7061E-01 6.5044E-02 -1.5426E-02 S6 1.8454E+00 -3.5830E-01 1.2577E-01 -4.1347E-02 S7 -8.3699E-01 6.3026E-02 3.3448E-02 -3.9771E-03 S8 -1.3684E+00 1.9897E-01 -2.3313E-02 9.0300E-03

[0285] Table 21

[0286] Figure 16a The on-axis chromatic aberration curve of the optical system of Embodiment 7 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 16b The astigmatism curves of the optical system of Embodiment 7 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 16c The distortion curves of the optical system of Example 7 are shown, representing the magnitude of distortion under different viewing angles. Figure 16d The relative illumination curves of the optical system in Example 7 are shown, representing the relative illumination corresponding to different field angles on the imaging plane. According to... Figures 16a to 16d As shown, the optical system given in Example 7 can achieve good imaging quality.

[0287] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, improvements, or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An optical system, characterized in that, The optical system includes: a first lens, a reflective polarizing element, a quarter-wave plate, a second lens, a third lens, and a display; wherein, The first lens to the third lens are arranged sequentially along the optical axis from the position furthest from the display to the position closest to the display; The reflective polarizing element and the quarter-wave plate are disposed between the first lens and the second lens; Each of the first to the third lenses has at least one far-light surface away from the display and at least one near-light surface close to the display; The far-light surface or the near-light surface of the at least one lens has a partial reflective layer; Wherein, the effective focal length f of the optical system and the combined focal length F12 of the first lens, the reflective polarizing element, the quarter-wave plate and the second lens satisfy: 0.96≤f / F12≤1.

04.

2. The optical system according to claim 1, characterized in that, The axial distance TD between the far-light surface of the first lens and the near-light surface of the third lens and the effective focal length f of the optical system satisfy: 0.43≤TD / f≤0.

73.

3. 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, and the refractive index N3 of the third lens satisfy: 1.92≤(N1+N2) / N3<2.

1.

4. The optical system according to claim 1, characterized in that, The reflective polarizing element includes at least one far-light surface away from the display and at least one near-light surface close to the display; the quarter-wave plate includes at least one far-light surface away from the display and at least one near-light surface close to the display. The near-light surface of the reflective polarizing element is in at least partial contact with the far-light surface of the quarter-wave plate.

5. The optical system according to claim 1, characterized in that, The reflective polarizing element includes at least one far-light surface away from the display and at least one near-light surface close to the display. The far-light surface of the reflective polarizing element is in at least partial contact with the near-light surface of the first lens.

6. The optical system according to claim 1, characterized in that, The dispersion coefficient V1 of the first lens, the dispersion coefficient V2 of the second lens, the center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, and the distance T12 between the near-light surface of the first lens and the far-light surface of the second lens on the optical axis satisfy: 42.79≤(V1×CT1+V2×CT2) / (CT1+T12+CT2)≤57.

39.

7. The optical system according to claim 1, characterized in that, The effective focal length f of the optical system and the distance FL between the near-light surface of the third lens and the display on the optical axis satisfy: 1.77≤f / FL≤4.

67.

8. The optical system according to claim 1, characterized in that, The dispersion coefficient V3 and the refractive index N3 of the third lens satisfy: 11.38≤V3 / N3≤40.

54.

9. The optical system according to claim 1, characterized in that, The radius of curvature R5 of the far-light surface of the third lens and the radius of curvature R6 of the near-light surface of the third lens satisfy: -0.74≤(R5-R6) / (R5+R6)≤0.

28.

10. The optical system according to claim 1, characterized in that, The distance T23 between the near-light surface of the second lens and the far-light surface of the third lens on the optical axis, and the center thickness CT3 of the third lens on the optical axis, satisfy: 0.39≤T23 / CT3≤1.

18.

11. The optical system according to claim 1, characterized in that, The reflective layer is coated on the near-light or far-light surface of the third lens.

12. The optical system according to claim 1, characterized in that, The refractive index NRP of the reflective polarizing element, the refractive index NQWP of the quarter-wave plate, the refractive index N1 of the first lens, and the refractive index N2 of the second lens satisfy: 0.93≤(NRP+NQWP) / (N1+N2)≤1.

01.

13. The optical system according to claim 1, characterized in that, The radius of curvature R1 of the far-light surface of the first lens and the radius of curvature R4 of the near-light surface of the second lens satisfy: 0.25≤(R1+R4) / (R1-R4)≤0.

95.

14. The optical system according to claim 1, characterized in that, The dispersion coefficient VRP of the reflective polarizing element, the dispersion coefficient VQWP of the quarter-wave plate, the center thickness CTR of the reflective polarizing element on the optical axis, the center thickness CTQWP of the quarter-wave plate on the optical axis, and the combined focal length F12 of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens satisfy: 1.5≤(VRP+VQWP)×(CTR+CTQWP) / F12≤1.

67.

15. The optical system according to claim 1, characterized in that, The maximum effective radius DT31 of the far-light surface of the third lens and the maximum effective radius DT32 of the near-light surface of the third lens satisfy: -0.18≤(DT31+DT32) / f3≤0.

28.

16. The optical system according to claim 1, characterized in that, The axial distance SAG31 between the intersection of the far-light surface and the optical axis of the third lens and the vertex of the effective radius of the far-light surface of the third lens, and the axial distance SAG32 between the intersection of the near-light surface and the optical axis of the third lens and the vertex of the effective radius of the near-light surface of the third lens, satisfy the following: 0.39≤|SAG31-SAG32| / CT3≤0.

67.

17. The optical system according to claim 1, characterized in that, The axial distance TD between the far-light surface of the first lens and the near-light surface of the third lens, and half of the maximum field of view (Semi-FOV) of the optical system, satisfy: Semi-FOV=53°; 17.13mm≤TD×tan(Semi-FOV)≤28.6mm.

18. The optical system according to claim 1, characterized in that, The radius of curvature of the far-light surface of the third lens is less than zero, and the radius of curvature of the near-light surface of the third lens is less than zero.

19. The optical system according to claim 1, characterized in that, The effective focal length f of the optical system and the focal length f3 of the third lens satisfy: -10.62≤f3 / f≤27.34.

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