An optical system

Abstract

The application discloses an optical system, comprising: a reflective polarizing element, a quarter-wave plate, a first lens, a second lens, a third lens and a display; the first lens to the third lens are sequentially arranged from the outside to the inside along the optical axis; the reflective polarizing element and the quarter-wave plate are arranged outside the first lens; each of the first lens to the third lens has at least one outer side surface away from the display and one inner side surface close to the display; the outer side surface or the inner side surface of at least one of the first lens to the third lens has a partial reflection layer; wherein the curvature radius R5 of the outer side surface of the third lens and the curvature radius R4 of the inner side surface of the second lens satisfy: 0 < R4 / R5. By controlling the ratio of the outer side curvature radius of the third lens and the inner side curvature radius of the second lens, on the one hand, the height of the light can be effectively controlled, thereby reducing the size of the display; on the other hand, the optical power of the system is reasonably distributed, which is beneficial to improving the aberration of the system.

Description

Technical Field

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

[0002] The folded optical path scheme is a major development direction for VR lenses. The optical path folding shortens the device's length, making the visual optics thinner and lighter. Currently, single-lens folded optical path systems have poor imaging at the edges of the field of view, easily causing dizziness and significantly reducing the user experience. This patent uses a three-piece folded optical path scheme to reduce the thickness of the VR system.

[0003] The preceding description is intended to provide general background information and does not necessarily constitute prior art. Summary of the Invention

[0004] This application aims to provide an optical system that adopts a three-piece folded optical path scheme, reducing the thickness of the VR system, solving the problem of poor imaging at the edge of the field of view, reducing dizziness, and enhancing the consumer experience.

[0005] This application provides an optical system comprising: a reflective polarizing element, a quarter-wave plate, a first lens, a second lens, a third lens, and a display; the first lens to the third lens are arranged sequentially from the outer side to the inner side along the optical axis; the reflective polarizing element and the quarter-wave plate are located outside the first lens; each of the first lens to the third lens has at least one outer surface away from the display and one inner surface close to the display; at least one of the first lens to the third lens has a partially reflective layer on its outer or inner surface; wherein the radius of curvature R5 of the outer surface of the third lens and the radius of curvature R4 of the inner surface of the second lens satisfy: 0 <R4 / R5。

[0006] This application provides an optical system, including: a reflective polarizing element, a quarter-wave plate, a first lens, a second lens, a third lens, and a display; the first lens to the third lens are arranged sequentially from the outer side to the inner side along the optical axis; the reflective polarizing element and the quarter-wave plate are located outside the first lens; each of the first to third lenses has at least one outer surface away from the display and one inner surface close to the display; the outer surface or inner surface of the at least one lens has a partially reflective layer; wherein, the effective focal length f of the imaging system, and the combined focal length f23 of the second lens and the third lens, satisfy: 1 <f23 / f<23。

[0007] According to one embodiment of this application, half of the maximum field of view of the optical system (semi-fov) and the axial distance TD from the outer surface of the first lens to the inner surface of the third lens satisfy: 12 <TD / tan(semi-fov)<18。

[0008] According to one embodiment of this application, the back focal length BL of the optical system and the axial distance TD from the outer surface of the first lens to the inner surface of the third lens satisfy: 1.6 <TD / BL<3。

[0009] According to one embodiment of this application, the dispersion coefficient VRP of the reflective polarizing element, the dispersion coefficient V1 of the first lens, and the dispersion coefficient V2 of the second lens satisfy: 0 <VRP / (V1+V2)<1。

[0010] According to one embodiment of this application, a portion of the reflective layer of the third lens is coated on the outer or inner surface of the third lens.

[0011] According to one embodiment of this application, the dispersion coefficient VQWP of the quarter-wave plate, the dispersion coefficient V3 of the third lens, and the dispersion coefficient V2 of the second lens satisfy: 0.5 <VQWP / (V2+V3)<2。

[0012] According to one embodiment of this application, the effective focal length f2 of the second lens and the effective focal length f of the optical system satisfy: 1 ​​< |f2 / f| < 18.

[0013] According to one embodiment of this application, the effective focal length f of the optical system, the effective focal length f1 of the first lens, and the effective focal length f3 of the third lens satisfy: -0.2 <f / f3-f / f1<0.4。

[0014] According to one embodiment of this application, the radius of curvature R5 of the outer surface of the third lens and the center thickness CT3 of the third lens on the optical axis satisfy: 18 < |R5 / CT3| < 40.

[0015] According to one embodiment of this application, the center thickness CT1 of the first lens on the optical axis and the refractive index N1 of the first lens satisfy: 0 <CT1 / CT2 / N1<5。

[0016] According to one embodiment of this application, the axial distance TTL from the outer surface of the first lens to the display, 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 center thickness CT3 of the third lens on the optical axis satisfy: 0.6 < (CT1 + CT2 + CT3) / TTL < 0.8.

[0017] According to one embodiment of this application, the radius of curvature of the inner surface of the third lens is less than zero.

[0018] The beneficial effects of this application are:

[0019] The optical system provided in this application includes multiple lenses, such as a first lens to a third lens. By controlling the ratio of the outer radius of curvature of the third lens to the inner radius of curvature of the second lens, the height of the light can be effectively controlled, thereby reducing the size of the display; on the other hand, the optical power of the system is reasonably allocated, which is beneficial to improving the aberrations of the system. Attached Figure Description

[0020] 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.

[0021] Figure 1 This is a schematic diagram of the optical system of this application;

[0022] Figure 2 This is a partially enlarged schematic diagram of the optical system of this application;

[0023] Figure 3 This is a schematic diagram of the optical system of this application;

[0024] Figures 4a to 4d These 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.

[0025] Figure 5 This is a schematic diagram of the optical system of this application;

[0026] 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.

[0027] Figure 7 This is a schematic diagram of the optical system of this application;

[0028] 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.

[0029] Figure 9 This is a schematic diagram of the optical system of this application;

[0030] Figures 10a to 10dThese 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.

[0031] Figure 11 This is a schematic diagram of the optical system of this application;

[0032] 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.

[0033] Figure 13 This is a schematic diagram of the optical system of this application;

[0034] 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.

[0035] Figure 15 This is a schematic diagram of the optical system of this application;

[0036] 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.

[0037] Figure 17 This is a schematic diagram of the optical system of this application;

[0038] Figures 18a to 18d These are the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illumination curve of the optical system embodiment 8 of this application, respectively.

[0039] Figure 19 This is a schematic diagram of the optical system of this application;

[0040] Figures 20a to 20d These are the on-axis chromatic aberration curve, astigmatism curve, distortion curve, and relative illuminance curve of embodiment 9 of the optical system of this application, respectively. Detailed Implementation

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] In the description of this application, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region. If the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane is called the image-side surface of the lens.

[0046] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formalized manner unless expressly so specified herein.

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The features, principles, and other aspects of this application will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] Exemplary Implementation

[0049] refer to Figure 1 and Figure 2 As shown, an exemplary optical system of the present application includes: a reflective polarizing element, a quarter-wave plate, a first lens, 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 the outside to the inside; the reflective polarizing element and the quarter-wave plate are placed outside the first lens; wherein, each of the first lens to the third lens has at least one outer side facing away from the display and one inner side facing close to the display, and wherein, a partial reflection layer is provided on the outer side or the inner side of at least one of the first lens to the third lens. In an embodiment of the present application, the reflective polarizing element can reflect light of a certain polarization direction and can transmit polarized light perpendicular to the reflected polarized light; the quarter-wave plate can convert linearly polarized light and circularly polarized light to each other, thereby changing the state of polarized light; the partial reflection element can reflect and transmit; the aspherical surface of the side of the first lens close to the display can be coated with a film and can achieve light path reflection.

[0050] In an exemplary embodiment of the present application, the radius of curvature R5 of the outer side of the third lens and the radius of curvature R4 of the inner side of the second lens satisfy: 0 < R4 / R5. By controlling the ratio of the outer curvature radius of the third lens and the inner curvature radius of the second lens, on the one hand, the height of light can be effectively controlled, thereby reducing the size of the display; on the other hand, the optical power of the system is reasonably distributed, which is beneficial to improving the aberration of the system. More specifically, the radius of curvature R5 of the outer side of the third lens and the radius of curvature R4 of the inner side of the second lens satisfy: 0.01 < R4 / R5.

[0051] In an exemplary embodiment of the present application, the effective focal length f of the imaging system and the combined focal length f23 of the second lens and the third lens satisfy: 1 < f23 / f < 23. In an embodiment of the present application, by controlling the effective focal length of the system and the combined focal length of the second lens and the third lens, the optical power of the system can be made reasonable, thereby improving the imaging quality of the system. More specifically, the effective focal length f of the imaging system and the combined focal length f23 of the second lens and the third lens satisfy: 1.01 < f23 / f < 22.99.

[0052] In an exemplary embodiment of the present application, the half of the maximum field angle of the optical system, semi-fov, and the on-axis distance TD from the outer side surface of the first lens to the inner side surface of the third lens satisfy: 12 < TD / tan(semi-fov) < 18. By controlling the ratio of the total length of the lens to the tangent of the maximum half field angle, the length of the entire optical system is shortened, the VR system is miniaturized, the weight of the VR product is reduced, and at the same time, the field angle of the system can be increased. More specifically, the half of the maximum field angle of the optical system, semi-fov, and the on-axis distance TD from the outer side surface of the first lens to the inner side surface of the third lens satisfy: 12.01 < TD / tan(semi-fov) < 17.99.

[0053] In an exemplary embodiment of the present application, the back focal length BL of the optical system and the on-axis distance TD from the outer side surface of the first lens to the inner side surface of the third lens satisfy: 1.6 < TD / BL < 3. In the embodiment of the present application, by controlling the on-axis distance from the outer side surface of the first lens to the inner side surface of the third lens and the back focal length of the imaging system, the system is made more compact, and at the same time, the light can be converged to improve the imaging quality. More specifically, the back focal length BL of the optical system and the on-axis distance TD from the outer side surface of the first lens to the inner side surface of the third lens satisfy: 1.61 < TD / BL < 2.99.

[0054] In an exemplary embodiment of the present application, the dispersion coefficient VRP of the reflective polarizing element, the dispersion coefficient V1 of the first lens, and the dispersion coefficient V2 of the second lens satisfy: 0 < VRP / (V1 + V2) < 1. In the embodiment of the present application, by controlling the dispersion coefficients of the first and second lenses, it is beneficial to select more conventional and more reasonable optical materials, and at the same time, the chromatic aberration of the system can be reduced. More specifically, the dispersion coefficient VRP of the reflective polarizing element, the dispersion coefficient V1 of the first lens, and the dispersion coefficient V2 of the second lens satisfy: 0.01 < VRP / (V1 + V2) < 0.99.

[0055] In an exemplary embodiment of the present application, a partial reflective layer of the third lens is plated on the outer side surface or the inner side surface of the third lens. By plating a reflective layer on the outer side surface or the inner side surface of the third lens, the reflective and transmissive properties of the reflective layer can be utilized to achieve a folded optical path, and at the same time, the reflective layer can be prevented from being frequently rubbed during use, thereby damaging the reflective layer.

[0056] In an exemplary embodiment of the present application, the dispersion coefficient VQWP of the quarter-wave plate, the dispersion coefficient V3 of the third lens, and the dispersion coefficient V2 of the second lens satisfy: 0.5 < VQWP / (V2 + V3) < 2. By controlling the ratio of the dispersion coefficient of the quarter-wave plate to the dispersion coefficients of the second and third lenses, the chromatic aberration introduced by the quarter-wave plate is reduced, which is beneficial to correcting the chromatic aberration of the system, improving the imaging quality, and enhancing the user experience. More specifically, the dispersion coefficient VQWP of the quarter-wave plate, the dispersion coefficient V3 of the third lens, and the dispersion coefficient V2 of the second lens satisfy: 0.51 < VQWP / (V2 + V3) < 1.99.

[0057] In an exemplary embodiment of the present application, the effective focal length f2 of the second lens and the effective focal length f of the optical system satisfy: 1 < |f2 / f| < 18. By controlling the ratio of the effective focal length of the second lens to the effective focal length of the imaging system, not only the optical power is reasonably distributed, but also the light rays can be converged, improving the performance of the system. More specifically, the effective focal length f2 of the second lens and the effective focal length f of the optical system satisfy: 1.01 < |f2 / f| < 17.99.

[0058] In an exemplary embodiment of the present application, the effective focal length f of the optical system, the effective focal length f1 of the first lens, and the effective focal length f3 of the third lens satisfy: -0.2 < f / f3 - f / f1 < 0.4. By controlling the effective focal length of the system and the effective focal lengths of the first and third lenses, the optical power can be reasonably distributed, and at the same time, the effective focal length can be reduced to shorten the optical system. Combining with coating a reflective layer on the lens and using a quarter-wave plate, the light path can be folded and reversed, making the visual optical device thinner and lighter. More specifically, the effective focal length f of the optical system, the effective focal length f1 of the first lens, and the effective focal length f3 of the third lens satisfy: -0.21 < f / f3 - f / f1 < 0.39.

[0059] In an exemplary embodiment of the present application, the radius of curvature R5 of the outer side surface of the third lens and the central thickness CT3 of the third lens on the optical axis satisfy: 18 < |R5 / CT3| < 40. By controlling the ratio of the radius of curvature of the outer side surface of the third lens to the central thickness of the lens, the optical path is effectively shortened, making the system more compact. At the same time, the bending degree of the lens is effectively controlled, expanding the field of view angle; in addition, it is also beneficial to the shaping of the third lens. More specifically, the radius of curvature R5 of the outer side surface of the third lens and the central thickness CT3 of the third lens on the optical axis satisfy: 18.01 < |R5 / CT3| < 39.99.

[0060] In an exemplary embodiment of the present application, the central thickness CT1 of the first lens on the optical axis and the refractive index N1 of the first lens satisfy: 0 < CT1 / CT2 / N1 < 5. By controlling the central thicknesses of the first lens and the second lens and the refractive index of the first lens, on the one hand, it is beneficial to reduce the processability of lens forming, and on the other hand, it helps to select reasonable and low-stress optical materials to avoid affecting the polarization state of the system, thereby improving the performance of the system. More specifically, the central thickness CT1 of the first lens on the optical axis and the refractive index N1 of the first lens satisfy: 0.01 < CT1 / CT2 / N1 < 4.99.

[0061] In an exemplary embodiment of the present application, the on-axis distance TTL from the outer side surface of the first lens to the display, 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 central thickness CT3 of the third lens on the optical axis satisfy: 0.6 < (CT1 + CT2 + CT3) / TTL < 0.8. By controlling the total length of the optical system and the central thicknesses of the first lens, the second lens, and the third lens, not only can the thickness of the lens be limited, but also the length of the optical system can be shortened, making the VR product lighter and more comfortable to wear. More specifically, the on-axis distance TTL from the outer side surface of the first lens to the display, 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 central thickness CT3 of the third lens on the optical axis satisfy: 0.61 < (CT1 + CT2 + CT3) / TTL < 0.79.

[0062] In an exemplary embodiment of the present application, the radius of curvature R6 of the inner side surface of the third lens satisfies: R6 < 0. By controlling the radius of curvature of the inner side surface of the third lens, the bending degree of the third lens can be effectively limited, thereby focusing the optical path and increasing the imaging effect. On the other hand, it can reduce the ghost image of the Display and the side surface of the display. More specifically, the radius of curvature R6 of the inner side surface of the third lens satisfies: R6 < -0.01.

[0063] In this exemplary embodiment, the outer side surface and the inner side surface of any one of the first lens E1 to the third lens E3 are aspherical surfaces, and the surface shape x of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0064]

[0065] where x is the sagitta of the 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 (that is, the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1); k is the conic coefficient; and Ai is the correction coefficient of the i-th order of the aspherical surface.

[0066] In this exemplary embodiment, the optical system may further include an aperture stop. The aperture stop may be positioned as needed, for example, it may be positioned between the object side and the first lens. Optionally, the optical system may further include a filter for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging plane.

[0067] The optical system according to the above embodiments of this application can employ multiple lenses, such as the three lenses described above. By rationally allocating the optical power, surface shape, center thickness of each lens, and on-axis spacing between each lens, the optical system achieves a small size and volume, a wide imaging range, and high imaging quality, while ensuring the ultra-thin design of the mobile phone.

[0068] In an exemplary embodiment, at least one of the mirror surfaces of each lens is an aspherical mirror surface; that is, at least one mirror surface from the outer surface of the first lens to the inner surface of the third lens is an aspherical mirror surface. The characteristic of an aspherical lens is that its curvature changes continuously from the lens center to the lens periphery. Unlike a spherical lens, which has a constant curvature from the lens center to the lens periphery, an aspherical lens has better curvature radius characteristics, offering advantages in improving distortion aberrations and astigmatism. By using an aspherical lens, aberrations occurring during imaging can be eliminated as much as possible, thereby improving image quality. Optionally, at least one of the outer and inner surfaces of each of the first, second, and third lenses is an aspherical mirror surface. Optionally, both the outer and inner surfaces of each of the first, second, and third lenses are aspherical mirror surfaces.

[0069] 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.

[0070] 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

[0072] Figure 3 This is a schematic diagram of the structure of the optical system of Embodiment 1 of this application. The optical system includes, in sequence along the optical axis from the object side to the image side: an aperture stop STO, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, and an imaging surface S9. Each of the first to third lenses has at least one outer surface away from the display and one inner surface close to the display; at least one of the first to third lenses has a partially reflective layer on its outer or inner surface.

[0073] The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display), which passes through a third lens, a second lens, a first lens, and a quarter-wave plate to become linearly polarized light. After being reflected by a reflective polarizing element, it passes through a quarter-wave plate, a first lens, and a second lens, and is partially reflected by a reflective layer on the third lens. Finally, it passes through a second lens, a first lens, a quarter-wave plate, and a reflective polarizing element before entering the human eye.

[0074] Table 1 shows the basic parameters of the optical system in Example 1, where the units for radius of curvature, thickness, and focal length are all millimeters (mm).

[0075]

[0076] Table 1

[0077] As shown in Table 2, in Example 1, the total effective focal length of the optical system is f = 30.12 mm, the back focal length of the optical system is BL = 8.47 mm, and half of the maximum field of view of the optical system is semi-fov = 53.0°.

[0078]

[0079] Table 2

[0080] The optical imaging lens in Example 1 satisfies:

[0081] R4 / R5 = 0.57, where R5 is the radius of curvature of the outer surface of the third lens and R4 is the radius of curvature of the inner surface of the second lens.

[0082] f23 / f = 2.13, where f is the effective focal length of the optical system and f23 is the combined focal length of the second and third lenses.

[0083] TD / tan(semi-fov) = 16.05, where semi-fov is half of the maximum field of view of the optical system, and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0084] TD / BL = 2.52, where BL is the back focal length of the optical system and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0085] VRP / (V1+V2)=0.76, where VRP is the dispersion coefficient of the reflective polarizing element, V1 is the dispersion coefficient of the first lens, and V2 is the dispersion coefficient of the second lens.

[0086] VQWP / (V2+V3)=0.76, where VQWP is the dispersion coefficient of the quarter-wave plate, V3 is the dispersion coefficient of the third lens, and V2 is the dispersion coefficient of the second lens.

[0087] |f2 / f|=2.93, where f2 is the effective focal length of the second lens and f is the effective focal length of the optical system.

[0088] f / f3-f / f1=0.28, where f is the effective focal length of the optical system, f1 is the effective focal length of the first lens, and f3 is the effective focal length of the third lens.

[0089] |R5 / CT3|=27.70, where R5 is the radius of curvature of the outer surface of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

[0090] CT1 / CT2 / N1 = 0.38, where CT1 is the center thickness of the first lens on the optical axis and N1 is the refractive index of the first lens.

[0091] (CT1+CT2+CT3) / TTL=0.71, where TTL is the axial distance from the outer surface of the first lens to the display, 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 CT3 is the center thickness of the third lens on the optical axis.

[0092] In Example 1, the outer and inner surfaces of any one of the first lens E1 to the third lens E3 are aspherical. Table 3 shows the higher-order coefficients A4, A6, A8, and A10 that can be used for each aspherical mirror S4, S5, S6, S7, and S8 in Example 1.

[0093] Face number A4 A6 A8 A10 S4 -6.6432E-02 1.8077E-01 -2.3484E-02 8.3382E-02 S5 2.6555E-01 2.5411E-02 -1.4336E-01 5.3124E-02 S6 -1.6482E-01 -3.0792E-01 6.8021E-03 -9.2293E-03 S7 1.3559E-01 2.0474E-04 -3.9216E-02 -4.7567E-03 S8 -2.4170E-02 -2.7007E-01 -1.9162E-01 -2.1132E-01

[0094] Table 3

[0095] Figure 4a The on-axis chromatic aberration curve of the optical system of Embodiment 1 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 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

[0097] Figure 5 This is a schematic diagram of the structure of embodiment 2 of the optical system of this application. The optical system includes, in sequence along the optical axis from the object side to the image side: aperture stop STO, reflective polarizing element RP, quarter-wave plate QWP, first lens E1, second lens E2, third lens E3, and imaging surface S9. Each of the first to third lenses has at least one outer surface away from the display and one inner surface close to the display; at least one of the first to third lenses has a partially reflective layer on its outer or inner surface.

[0098] The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display), which passes through a third lens, a second lens, a first lens, and a quarter-wave plate to become linearly polarized light. After being reflected by a reflective polarizing element, it passes through a quarter-wave plate, a first lens, and a second lens, and is partially reflected by a reflective layer on the third lens. Finally, it passes through a second lens, a first lens, a quarter-wave plate, and a reflective polarizing element before entering the human eye.

[0099] Table 4 shows the basic parameters of the optical system in Example 2, where the units for radius of curvature, thickness, and focal length are all millimeters (mm).

[0100]

[0101]

[0102] Table 4

[0103] As shown in Table 5, in Example 2, the total effective focal length of the optical system is f = 30.11 mm, the back focal length of the optical system is BL = 8.61 mm, and half of the maximum field of view of the optical system is semi-fov = 53.0°.

[0104]

[0105] Table 5

[0106] The optical imaging lens in Example 2 satisfies:

[0107] R4 / R5 = 0.57, where R5 is the radius of curvature of the outer surface of the third lens and R4 is the radius of curvature of the inner surface of the second lens.

[0108] f23 / f = 2.15, where f is the effective focal length of the optical system and f23 is the combined focal length of the second and third lenses.

[0109] TD / tan(semi-fov) = 15.96, where semi-fov is half of the maximum field of view of the optical system, and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0110] TD / BL = 2.46, where BL is the back focal length of the optical system and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0111] VRP / (V1+V2)=0.76, where VRP is the dispersion coefficient of the reflective polarizing element, V1 is the dispersion coefficient of the first lens, and V2 is the dispersion coefficient of the second lens.

[0112] VQWP / (V2+V3)=0.76, where VQWP is the dispersion coefficient of the quarter-wave plate, V3 is the dispersion coefficient of the third lens, and V2 is the dispersion coefficient of the second lens.

[0113] |f2 / f|=2.95, where f2 is the effective focal length of the second lens and f is the effective focal length of the optical system.

[0114] f / f3-f / f1=0.27, where f is the effective focal length of the optical system, f1 is the effective focal length of the first lens, and f3 is the effective focal length of the third lens.

[0115] |R5 / CT3|=27.82, where R5 is the radius of curvature of the outer surface of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

[0116] CT1 / CT2 / N1 = 0.37, where CT1 is the center thickness of the first lens on the optical axis and N1 is the refractive index of the first lens.

[0117] (CT1+CT2+CT3) / TTL=0.70, where TTL is the axial distance from the outer surface of the first lens to the display, 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 CT3 is the center thickness of the third lens on the optical axis.

[0118] In Example 2, the outer and inner surfaces of any one of the first lens E1 to the third lens E3 are aspherical. Table 6 shows the higher-order coefficients A4, A6, A8, and A10 that can be used for each aspherical mirror S4, S5, S6, S7, and S8 in Example 2.

[0119] Face number A4 A6 A8 A10 S4 -6.1614E-02 1.7339E-01 -2.4843E-02 7.8343E-02 S5 2.6900E-01 1.7790E-02 -1.4264E-01 4.7371E-02 S6 -1.6866E-01 -3.0515E-01 9.9349E-03 -9.4345E-03 S7 1.3929E-01 -4.9698E-04 -3.9605E-02 -4.7729E-03 S8 -3.2983E-02 -2.7075E-01 -1.9221E-01 -2.0574E-01

[0120] Table 6

[0121] 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 6cThe 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 6d As shown, the optical system given in Example 2 can achieve good imaging quality. Specific Implementation Example 3

[0123] Figure 7 This is a schematic diagram of the structure of the optical system embodiment 3 of this application. The optical system includes, in sequence along the optical axis from the object side to the image side: an aperture stop STO, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, and an imaging surface S9. Each of the first to third lenses has at least one outer surface away from the display and one inner surface close to the display; at least one of the first to third lenses has a partially reflective layer on its outer or inner surface.

[0124] The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display), which passes through a third lens, a second lens, a first lens, and a quarter-wave plate to become linearly polarized light. After being reflected by a reflective polarizing element, it passes through a quarter-wave plate, a first lens, and a second lens, and is partially reflected by a reflective layer on the third lens. Finally, it passes through a second lens, a first lens, a quarter-wave plate, and a reflective polarizing element before entering the human eye.

[0125] Table 7 shows the basic parameters of the optical system in Example 3, where the units for radius of curvature, thickness, and focal length are millimeters (mm).

[0126]

[0127]

[0128] Table 7

[0129] As shown in Table 8, in Example 3, the total effective focal length of the optical system is f = 30.11 mm, the back focal length of the optical system is BL = 8.61 mm, and half of the maximum field of view of the optical system is semi-fov = 53.0°.

[0130]

[0131] Table 8

[0132] The optical imaging lens in Example 3 satisfies:

[0133] R4 / R5 = 0.57, where R5 is the radius of curvature of the outer surface of the third lens and R4 is the radius of curvature of the inner surface of the second lens.

[0134] f23 / f = 2.14, where f is the effective focal length of the optical system and f23 is the combined focal length of the second and third lenses.

[0135] TD / tan(semi-fov) = 16.07, where semi-fov is half of the maximum field of view of the optical system, and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0136] TD / BL = 2.53, where BL is the back focal length of the optical system and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0137] VRP / (V1+V2)=0.76, where VRP is the dispersion coefficient of the reflective polarizing element, V1 is the dispersion coefficient of the first lens, and V2 is the dispersion coefficient of the second lens.

[0138] VQWP / (V2+V3)=0.76, where VQWP is the dispersion coefficient of the quarter-wave plate, V3 is the dispersion coefficient of the third lens, and V2 is the dispersion coefficient of the second lens.

[0139] |f2 / f|=2.93, where f2 is the effective focal length of the second lens and f is the effective focal length of the optical system.

[0140] f / f3-f / f1=0.28, where f is the effective focal length of the optical system, f1 is the effective focal length of the first lens, and f3 is the effective focal length of the third lens.

[0141] |R5 / CT3|=27.62, where R5 is the radius of curvature of the outer surface of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

[0142] CT1 / CT2 / N1 = 0.38, where CT1 is the center thickness of the first lens on the optical axis and N1 is the refractive index of the first lens.

[0143] (CT1+CT2+CT3) / TTL=0.71, where TTL is the axial distance from the outer surface of the first lens to the display, 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 CT3 is the center thickness of the third lens on the optical axis.

[0144] In Example 3, the outer and inner surfaces of any one of the first lens E1 to the third lens E3 are aspherical. Table 9 shows the higher-order coefficients A4, A6, A8, and A10 that can be used for each aspherical mirror S4, S5, S6, S7, and S8 in Example 3.

[0145] Face number A4 A6 A8 A10 S4 -6.6527E-02 1.8159E-01 -2.4477E-02 8.0683E-02 S5 2.6579E-01 2.6581E-02 -1.4476E-01 4.9900E-02 S6 -1.6607E-01 -3.0752E-01 5.8513E-03 -9.0554E-03 S7 1.3990E-01 -1.1824E-03 -3.8568E-02 -4.6415E-03 S8 -2.9602E-02 -2.6835E-01 -1.9086E-01 -2.1205E-01

[0146] Table 9

[0147] 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

[0149] Figure 9 This is a schematic diagram of the structure of embodiment 4 of the optical system of this application. The optical system includes, in sequence along the optical axis from the object side to the image side: an aperture stop STO, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, and an imaging surface S9. Each of the first to third lenses has at least one outer surface away from the display and one inner surface close to the display; at least one of the first to third lenses has a partially reflective layer on its outer or inner surface.

[0150] The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display), which passes through a third lens, a second lens, a first lens, and a quarter-wave plate to become linearly polarized light. After being reflected by a reflective polarizing element, it passes through a quarter-wave plate, a first lens, and a second lens, and is partially reflected by a reflective layer on the third lens. Finally, it passes through a second lens, a first lens, a quarter-wave plate, and a reflective polarizing element before entering the human eye.

[0151] Table 10 shows the basic parameters of the optical system in Example 4, where the units for radius of curvature, thickness, and focal length are all millimeters (mm).

[0152]

[0153] Table 10

[0154] As shown in Table 11, in Example 4, the total effective focal length of the optical system is f = 30.07 mm, the back focal length of the optical system is BL = 10.11 mm, and half of the maximum field of view of the optical system is semi-fov = 53.0°.

[0155]

[0156]

[0157] Table 11

[0158] The optical imaging lens in Example 4 satisfies:

[0159] R4 / R5 = 0.56, where R5 is the radius of curvature of the outer surface of the third lens and R4 is the radius of curvature of the inner surface of the second lens.

[0160] f23 / f = 21.61, where f is the effective focal length of the optical system and f23 is the combined focal length of the second and third lenses.

[0161] TD / tan(semi-fov) = 14.45, where semi-fov is half of the maximum field of view of the optical system, and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0162] TD / BL = 1.90, where BL is the back focal length of the optical system and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0163] VRP / (V1+V2)=0.76, where VRP is the dispersion coefficient of the reflective polarizing element, V1 is the dispersion coefficient of the first lens, and V2 is the dispersion coefficient of the second lens.

[0164] VQWP / (V2+V3)=1.50, where VQWP is the dispersion coefficient of the quarter-wave plate, V3 is the dispersion coefficient of the third lens, and V2 is the dispersion coefficient of the second lens.

[0165] |f2 / f|=9.50, where f2 is the effective focal length of the second lens and f is the effective focal length of the optical system.

[0166] f / f3-f / f1=-0.16, where f is the effective focal length of the optical system, f1 is the effective focal length of the first lens, and f3 is the effective focal length of the third lens.

[0167] |R5 / CT3|=37.82, where R5 is the radius of curvature of the outer surface of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

[0168] CT1 / CT2 / N1 = 4.39, where CT1 is the center thickness of the first lens on the optical axis and N1 is the refractive index of the first lens.

[0169] (CT1+CT2+CT3) / TTL=0.65, where TTL is the axial distance from the outer surface of the first lens to the display, 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 CT3 is the center thickness of the third lens on the optical axis.

[0170] In Example 4, the outer and inner surfaces of any one of the first lens E1 to the third lens E3 are aspherical. Table 12 shows the higher-order coefficients A4, A6, A8, and A10 that can be used for each aspherical mirror S4, S5, S6, S7, and S8 in Example 4.

[0171]

[0172]

[0173] Table 12

[0174] 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

[0176] Figure 11 This is a schematic diagram of the structure of embodiment 5 of the optical system of this application. The optical system includes, in sequence along the optical axis from the object side to the image side: an aperture stop STO, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, and an imaging surface S9. Each of the first to third lenses has at least one outer surface away from the display and one inner surface close to the display; at least one of the first to third lenses has a partially reflective layer on its outer or inner surface.

[0177] The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display), which passes through a third lens, a second lens, a first lens, and a quarter-wave plate to become linearly polarized light. After being reflected by a reflective polarizing element, it passes through a quarter-wave plate, a first lens, and a second lens, and is partially reflected by a reflective layer on the third lens. Finally, it passes through a second lens, a first lens, a quarter-wave plate, and a reflective polarizing element before entering the human eye.

[0178] Table 13 shows the basic parameters of the optical system in Example 5, where the units for radius of curvature, thickness, and focal length are all millimeters (mm).

[0179]

[0180]

[0181] Table 13

[0182] As shown in Table 14, in Example 5, the total effective focal length of the optical system is f = 30.07 mm, the back focal length of the optical system is BL = 10.09 mm, and half of the maximum field of view of the optical system is semi-fov = 53.0°.

[0183]

[0184] Table 14

[0185] The optical imaging lens in Example 5 satisfies:

[0186] R4 / R5 = 0.55, where R5 is the radius of curvature of the outer surface of the third lens and R4 is the radius of curvature of the inner surface of the second lens.

[0187] f23 / f = 21.22, where f is the effective focal length of the optical system and f23 is the combined focal length of the second and third lenses.

[0188] TD / tan(semi-fov) = 14.49, where semi-fov is half of the maximum field of view of the optical system, and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0189] TD / BL = 1.91, where BL is the back focal length of the optical system and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0190] VRP / (V1+V2)=0.76, where VRP is the dispersion coefficient of the reflective polarizing element, V1 is the dispersion coefficient of the first lens, and V2 is the dispersion coefficient of the second lens.

[0191] VQWP / (V2+V3)=1.50, where VQWP is the dispersion coefficient of the quarter-wave plate, V3 is the dispersion coefficient of the third lens, and V2 is the dispersion coefficient of the second lens.

[0192] |f2 / f|=9.38, where f2 is the effective focal length of the second lens and f is the effective focal length of the optical system.

[0193] f / f3-f / f1=-0.16, where f is the effective focal length of the optical system, f1 is the effective focal length of the first lens, and f3 is the effective focal length of the third lens.

[0194] |R5 / CT3|=37.21, where R5 is the radius of curvature of the outer surface of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

[0195] CT1 / CT2 / N1 = 4.39, where CT1 is the center thickness of the first lens on the optical axis and N1 is the refractive index of the first lens.

[0196] (CT1+CT2+CT3) / TTL=0.65, where TTL is the axial distance from the outer surface of the first lens to the display, 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 CT3 is the center thickness of the third lens on the optical axis.

[0197] In Example 5, the outer and inner surfaces of any one of the first lens E1 to the third lens E3 are aspherical. Table 15 shows the higher-order coefficients A4, A6, A8, and A10 that can be used for each aspherical mirror S4, S5, S6, S7, and S8 in Example 5.

[0198] Face number A4 A6 A8 A10 S4 -2.6881E-01 -1.2922E-01 1.0970E-01 2.5525E-02 S5 2.2770E-01 1.6278E-01 7.1019E-02 6.6719E-03 S6 1.6235E-01 2.2419E-01 9.8899E-02 -3.1348E-02 S7 -1.5901E-01 1.0397E-01 -8.0840E-02 5.8104E-03 S8 2.7500E-02 -2.5505E-01 -3.6861E-01 3.3742E-02

[0199] Table 15

[0200] 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 shown, the optical system given in Example 5 can achieve good imaging quality. Specific Implementation Example 6

[0202] Figure 13This is a schematic diagram of the structure of embodiment 6 of the optical system of this application. The optical system includes, in sequence along the optical axis from the object side to the image side: an aperture stop STO, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, and an imaging surface S9. Each of the first to third lenses has at least one outer surface away from the display and one inner surface close to the display; at least one of the first to third lenses has a partially reflective layer on its outer or inner surface.

[0203] The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display), which passes through a third lens, a second lens, a first lens, and a quarter-wave plate to become linearly polarized light. After being reflected by a reflective polarizing element, it passes through a quarter-wave plate, a first lens, and a second lens, and is partially reflected by a reflective layer on the third lens. Finally, it passes through a second lens, a first lens, a quarter-wave plate, and a reflective polarizing element before entering the human eye.

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

[0205]

[0206] Table 16

[0207] As shown in Table 17, in Example 6, the total effective focal length of the optical system is f = 34.87 mm, the back focal length of the optical system is BL = 6.70 mm, and half of the maximum field of view of the optical system is semi-fov = 53.0°.

[0208]

[0209] Table 17

[0210] The optical imaging lens in Example 6 satisfies:

[0211] R4 / R5 = 1.18, where R5 is the radius of curvature of the outer surface of the third lens and R4 is the radius of curvature of the inner surface of the second lens.

[0212] f23 / f = 7.51, where f is the effective focal length of the optical system and f23 is the combined focal length of the second and third lenses.

[0213] TD / tan(semi-fov) = 14.65, where semi-fov is half of the maximum field of view of the optical system, and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0214] TD / BL = 2.90, where BL is the back focal length of the optical system and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0215] VRP / (V1+V2)=0.89, where VRP is the dispersion coefficient of the reflective polarizing element, V1 is the dispersion coefficient of the first lens, and V2 is the dispersion coefficient of the second lens.

[0216] VQWP / (V2+V3)=1.03, where VQWP is the dispersion coefficient of the quarter-wave plate, V3 is the dispersion coefficient of the third lens, and V2 is the dispersion coefficient of the second lens.

[0217] |f2 / f|=8.99, where f2 is the effective focal length of the second lens and f is the effective focal length of the optical system.

[0218] f / f3-f / f1=0.11, where f is the effective focal length of the optical system, f1 is the effective focal length of the first lens, and f3 is the effective focal length of the third lens.

[0219] |R5 / CT3|=19.55, where R5 is the radius of curvature of the outer surface of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

[0220] CT1 / CT2 / N1 = 2.84, where CT1 is the center thickness of the first lens on the optical axis and N1 is the refractive index of the first lens.

[0221] (CT1+CT2+CT3) / TTL=0.73, where TTL is the axial distance from the outer surface of the first lens to the display, 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 CT3 is the center thickness of the third lens on the optical axis.

[0222] In Example 6, the outer and inner surfaces of any one of the first lens E1 to the third lens E3 are aspherical. Table 18 shows the higher-order coefficients A4, A6, A8, and A10 that can be used for each aspherical mirror S4, S5, S6, S7, and S8 in Example 6.

[0223] Face number A4 A6 A8 A10 S4 -3.7153E-01 -4.4802E-02 -5.8708E-02 -7.3130E-02 S5 2.3781E-01 7.4424E-02 -1.3454E-01 -6.6143E-02 S6 5.3256E-02 1.5066E-01 -1.5517E-01 -1.3284E-02 S7 2.8881E-01 -1.6154E-02 -8.8647E-02 -6.4073E-03 S8 1.2345E-01 -2.7763E-02 -5.1112E-03 -6.6015E-03

[0224] Table 18

[0225] 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 14cThe 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

[0227] Figure 15 This is a schematic diagram of the structure of embodiment 7 of the optical system of this application. The optical system includes, in sequence along the optical axis from the object side to the image side: an aperture stop STO, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, and an imaging surface S9. Each of the first to third lenses has at least one outer surface away from the display and one inner surface close to the display; at least one of the first to third lenses has a partially reflective layer on its outer or inner surface.

[0228] The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display), which passes through a third lens, a second lens, a first lens, and a quarter-wave plate to become linearly polarized light. After being reflected by a reflective polarizing element, it passes through a quarter-wave plate, a first lens, and a second lens, and is partially reflected by a reflective layer on the third lens. Finally, it passes through a second lens, a first lens, a quarter-wave plate, and a reflective polarizing element before entering the human eye.

[0229] Table 19 shows the basic parameters of the optical system in Example 7, where the units for radius of curvature, thickness, and focal length are all millimeters (mm).

[0230]

[0231]

[0232] Table 19

[0233] As shown in Table 20, in Example 7, the total effective focal length of the optical system is f = 30.36 mm, the back focal length of the optical system is BL = 9.18 mm, and half of the maximum field of view of the optical system is semi-fov = 53.0°.

[0234]

[0235] Table 20

[0236] The optical imaging lens in Example 7 satisfies:

[0237] R4 / R5 = 1.02, where R5 is the radius of curvature of the outer surface of the third lens and R4 is the radius of curvature of the inner surface of the second lens.

[0238] f23 / f = 4.92, where f is the effective focal length of the optical system and f23 is the combined focal length of the second and third lenses.

[0239] TD / tan(semi-fov) = 13.17, where semi-fov is half of the maximum field of view of the optical system, and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0240] TD / BL = 1.90, where BL is the back focal length of the optical system and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0241] VRP / (V1+V2)=0.51, where VRP is the dispersion coefficient of the reflective polarizing element, V1 is the dispersion coefficient of the first lens, and V2 is the dispersion coefficient of the second lens.

[0242] VQWP / (V2+V3)=0.76, where VQWP is the dispersion coefficient of the quarter-wave plate, V3 is the dispersion coefficient of the third lens, and V2 is the dispersion coefficient of the second lens.

[0243] |f2 / f|=3.33, where f2 is the effective focal length of the second lens and f is the effective focal length of the optical system.

[0244] f / f3-f / f1=-0.13, where f is the effective focal length of the optical system, f1 is the effective focal length of the first lens, and f3 is the effective focal length of the third lens.

[0245] |R5 / CT3|=38.46, where R5 is the radius of curvature of the outer surface of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

[0246] CT1 / CT2 / N1 = 0.45, where CT1 is the center thickness of the first lens on the optical axis and N1 is the refractive index of the first lens.

[0247] (CT1+CT2+CT3) / TTL=0.65, where TTL is the axial distance from the outer surface of the first lens to the display, 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 CT3 is the center thickness of the third lens on the optical axis.

[0248] In Example 7, the outer and inner surfaces of any one of the first lens E1 to the third lens E3 are aspherical. Table 21 shows the higher-order coefficients A4, A6, A8, and A10 that can be used for each aspherical mirror S4, S5, S6, S7, and S8 in Example 7.

[0249] Face number A4 A6 A8 A10 S4 -2.5894E-01 6.2046E-02 1.1381E-01 3.0973E-02 S5 2.8157E-01 -7.9651E-03 1.8648E-02 2.2692E-02 S6 -2.6424E-01 -7.5703E-02 3.2181E-02 -6.5222E-02 S7 7.3736E-02 -4.4217E-02 5.3652E-02 2.1837E-02 S8 1.3903E-01 -3.7049E-02 -5.1200E-03 2.1125E-02

[0250] Table 21

[0251] 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. Specific Implementation Example 8

[0253] Figure 17 This is a schematic diagram of the structure of embodiment 8 of the optical system of this application. The optical system includes, in sequence along the optical axis from the object side to the image side: an aperture stop STO, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, and an imaging surface S9. Each of the first to third lenses has at least one outer surface away from the display and one inner surface close to the display; at least one of the first to third lenses has a partially reflective layer on its outer or inner surface.

[0254] The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display), which passes through a third lens, a second lens, a first lens, and a quarter-wave plate to become linearly polarized light. After being reflected by a reflective polarizing element, it passes through a quarter-wave plate, a first lens, and a second lens, and is partially reflected by a reflective layer on the third lens. Finally, it passes through a second lens, a first lens, a quarter-wave plate, and a reflective polarizing element before entering the human eye.

[0255] Table 22 shows the basic parameters of the optical system in Example 8, where the units for radius of curvature, thickness, and focal length are all millimeters (mm).

[0256]

[0257] Table 22

[0258] As shown in Table 23, in Example 8, the total effective focal length of the optical system is f = 30.40 mm, the back focal length of the optical system is BL = 8.48 mm, and half of the maximum field of view of the optical system is semi-fov = 53.0°.

[0259]

[0260] Table 23

[0261] The optical imaging lens in Example 8 satisfies:

[0262] R4 / R5 = 1.01, where R5 is the radius of curvature of the outer surface of the third lens and R4 is the radius of curvature of the inner surface of the second lens.

[0263] f23 / f = 4.87, where f is the effective focal length of the optical system and f23 is the combined focal length of the second and third lenses.

[0264] TD / tan(semi-fov) = 13.58, where semi-fov is half of the maximum field of view of the optical system, and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0265] TD / BL = 2.12, where BL is the back focal length of the optical system and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0266] VRP / (V1+V2)=0.51, where VRP is the dispersion coefficient of the reflective polarizing element, V1 is the dispersion coefficient of the first lens, and V2 is the dispersion coefficient of the second lens.

[0267] VQWP / (V2+V3)==0.76, where VQWP is the dispersion coefficient of the quarter-wave plate, V3 is the dispersion coefficient of the third lens, and V2 is the dispersion coefficient of the second lens.

[0268] |f2 / f|=3.18, where f2 is the effective focal length of the second lens and f is the effective focal length of the optical system.

[0269] f / f3-f / f1=-0.14, where f is the effective focal length of the optical system, f1 is the effective focal length of the first lens, and f3 is the effective focal length of the third lens.

[0270] |R5 / CT3|=38.13, where R5 is the radius of curvature of the outer surface of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

[0271] CT1 / CT2 / N1 = 0.49, where CT1 is the center thickness of the first lens on the optical axis and N1 is the refractive index of the first lens.

[0272] (CT1+CT2+CT3) / TTL=0.67, where TTL is the axial distance from the outer surface of the first lens to the display, 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 CT3 is the center thickness of the third lens on the optical axis.

[0273] In Example 8, the outer and inner surfaces of any one of the first lens E1 to the third lens E3 are aspherical. Table 24 shows the higher-order coefficients A4, A6, A8, and A10 that can be used for each aspherical mirror S4, S5, S6, S7, and S8 in Example 8.

[0274] Face number A4 A6 A8 A10 S4 -2.3487E-01 1.1152E-01 1.3048E-01 3.3202E-02 S5 2.6863E-01 9.0567E-02 1.9499E-03 2.1137E-02 S6 -2.4497E-01 -1.1461E-01 -3.5037E-03 -7.7335E-02 S7 5.8905E-03 -7.1838E-02 3.1575E-02 1.9942E-02 S8 1.0094E-01 -2.3879E-02 -1.3684E-02 2.3331E-02

[0275] Table 24

[0276] Figure 18a The on-axis chromatic aberration curve of the optical system of Embodiment 8 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 18b The astigmatism curves of the optical system of Example 8 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 18c The distortion curves of the optical system of Example 8 are shown, representing the magnitude of distortion under different viewing angles. Figure 18d The relative illumination curves of the optical system in Example 8 are shown, representing the relative illumination corresponding to different field angles on the imaging plane. According to... Figures 18a to 18d As can be seen from the figure, the optical system given in Example 8 can achieve good imaging quality. Specific Implementation Example 9

[0278] Figure 19 This is a schematic diagram of the structure of embodiment 9 of the optical system of this application. The optical system includes, in sequence along the optical axis from the object side to the image side: an aperture stop STO, a reflective polarizing element RP, a quarter-wave plate QWP, a first lens E1, a second lens E2, a third lens E3, and an imaging surface S9. Each of the first to third lenses has at least one outer surface away from the display and one inner surface close to the display; at least one of the first to third lenses has a partially reflective layer on its outer or inner surface.

[0279] The display emits circularly polarized light (a quarter-wave plate is attached to the front of the display), which passes through a third lens, a second lens, a first lens, and a quarter-wave plate to become linearly polarized light. After being reflected by a reflective polarizing element, it passes through a quarter-wave plate, a first lens, and a second lens, and is partially reflected by a reflective layer on the third lens. Finally, it passes through a second lens, a first lens, a quarter-wave plate, and a reflective polarizing element before entering the human eye.

[0280] Table 25 shows the basic parameters of the optical system in Example 9, where the units for radius of curvature, thickness, and focal length are all millimeters (mm).

[0281]

[0282]

[0283] Table 25

[0284] As shown in Table 26, in Example 9, the total effective focal length of the optical system is f = 30.70 mm, the back focal length of the optical system is BL = 30.70 mm, and half of the maximum field of view of the optical system is semi-fov = 53.0°.

[0285]

[0286] Table 26

[0287] The optical imaging lens in Example 9 satisfies:

[0288] R4 / R5 = 2.93, where R5 is the radius of curvature of the outer surface of the third lens and R4 is the radius of curvature of the inner surface of the second lens.

[0289] f23 / f = 6.12, where f is the effective focal length of the optical system and f23 is the combined focal length of the second and third lenses.

[0290] TD / tan(semi-fov) = 13.93, where semi-fov is half of the maximum field of view of the optical system, and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0291] TD / BL = 2.28, where BL is the back focal length of the optical system and TD is the on-axis distance from the outer surface of the first lens to the inner surface of the third lens.

[0292] VRP / (V1+V2)=0.76, where VRP is the dispersion coefficient of the reflective polarizing element, V1 is the dispersion coefficient of the first lens, and V2 is the dispersion coefficient of the second lens.

[0293] VQWP / (V2+V3)=0.76, where VQWP is the dispersion coefficient of the quarter-wave plate, V3 is the dispersion coefficient of the third lens, and V2 is the dispersion coefficient of the second lens.

[0294] |f2 / f|=16.82, where f2 is the effective focal length of the second lens and f is the effective focal length of the optical system.

[0295] f / f3-f / f1=0.15, where f is the effective focal length of the optical system, f1 is the effective focal length of the first lens, and f3 is the effective focal length of the third lens.

[0296] |R5 / CT3|=20.90, where R5 is the radius of curvature of the outer surface of the third lens, and CT3 is the center thickness of the third lens on the optical axis.

[0297] CT1 / CT2 / N1 = 2.35, where CT1 is the center thickness of the first lens on the optical axis and N1 is the refractive index of the first lens.

[0298] (CT1+CT2+CT3) / TTL=0.69, where TTL is the axial distance from the outer surface of the first lens to the display, 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 CT3 is the center thickness of the third lens on the optical axis.

[0299] In Example 9, the outer and inner surfaces of any one of the first lens E1 to the third lens E3 are aspherical. Table 27 shows the higher-order coefficients A4, A6, A8, and A10 that can be used for each aspherical mirror S4, S5, S6, S7, and S8 in Example 9.

[0300] Face number A4 A6 A8 A10 S4 -3.2811E-01 1.0474E-01 8.3547E-02 3.2334E-02 S5 3.3830E-01 -2.3729E-02 -1.1123E-01 4.9376E-02 S6 -2.4618E-01 1.2666E-02 -2.3290E-01 5.9330E-02 S7 3.4149E-01 2.1810E-02 -9.0164E-02 -7.2288E-03 S8 1.9815E-01 -3.4108E-02 -1.9761E-02 -1.2540E-02

[0301] Table 27

[0302] Figure 20a The on-axis chromatic aberration curve of the optical system of Embodiment 9 is shown, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 20b The astigmatism curves of the optical system of Embodiment 9 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 20c The distortion curves of the optical system of Example 9 are shown, representing the magnitude of distortion under different viewing angles. Figure 20d The relative illumination curves of the optical system of Example 9 are shown, representing the relative illumination corresponding to different field angles on the imaging plane. According to... Figures 20a to 20d As can be seen from the figure, the optical system given in Example 9 can achieve good imaging quality.

[0303] 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 by comprising: The optical system comprises a reflective polarizer, a quarter wave plate, a first lens, a second lens, a third lens, and a display; The first lens to the third lens are arranged in order from outside to inside along the optical axis; The reflective polarizer and the quarter wave plate are arranged outside the first lens; Each of the first lens to the third lens has at least one outer side surface away from the display and one inner side surface close to the display; At least one of the outer side surface or the inner side surface of the first lens to the third lens has a partial reflection layer; The number of lenses with optical power in the optical system is three; only one of the first lens to the third lens is negative; The outer side surface of the first lens is a plane; The inner side surface of the third lens is a convex surface; The radius of curvature R6 of the inner side surface of the third lens satisfies R6 < 0; Wherein, the radius of curvature R5 of the outer side surface of the third lens, the radius of curvature R4 of the inner side surface of the second lens satisfy 0.55≤R4 / R5≤2.93; The radius of curvature R5 of the outer side surface of the third lens, and the central thickness CT3 of the third lens on the optical axis satisfy 19.55≤|R5 / CT3|≤38.46; 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 refractive index N1 of the first lens satisfy 0.37≤CT1 / CT2 / N1≤4.

39.

2. The optical system of claim 1, wherein Half of the maximum field angle semi-fov of the optical system and the axial distance TD from the outer side surface of the first lens to the inner side surface of the third lens satisfy 13.17≤TD / tan(semi-fov)≤16.

07.

3. The optical system of claim 1, wherein The back focal length BL of the optical system and the axial distance TD from the outer side surface of the first lens to the inner side surface of the third lens satisfy 1.9≤TD / BL≤2.

9.

4. The optical system of claim 1, wherein The dispersion coefficient VRP of the reflective polarizer, the dispersion coefficient V1 of the first lens, and the dispersion coefficient V2 of the second lens satisfy 0.51≤VRP / (V1+V2)≤0.

89.

5. The optical system of claim 1, wherein The partial reflection layer of the third lens is plated on the outer side surface or the inner side surface of the third lens.

6. The optical system of claim 1, wherein The dispersion coefficient VQWP of the quarter wave plate, the dispersion coefficient V3 of the third lens, and the dispersion coefficient V2 of the second lens satisfy 0.76≤VQWP / (V2+V3)≤1.

5.

7. The optical system of claim 1, wherein The effective focal length f2 of the second lens and the effective focal length f of the optical system satisfy 2.93≤|f2 / f|≤16.

82.

8. The optical system of claim 1, wherein, The effective focal length f of the optical system, the effective focal length f1 of the first lens, and the effective focal length f3 of the third lens satisfy -0.16≤f / f3-f / f1≤0.

28.

9. The optical system of claim 1, wherein, An on-axis distance TTL from the first lens outer side surface to the display, a center thickness CT1 of the first lens on the optical axis, a center thickness CT2 of the second lens on the optical axis, and a center thickness CT3 of the third lens on the optical axis satisfy: 0.65 ≤ (CT1 + CT2 + CT3) / TTL ≤ 0.

73.

10. The optical system of claim 1, wherein, An effective focal length f of the optical system, and a combined focal length f23 of the second lens and the third lens satisfy: 2.13 ≤ f23 / f ≤ 21.61.

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