Optical system and optical device including the optical system

Abstract

The application discloses an optical system, which comprises a first lens group, a second lens and a third lens in sequence from a first side to a second side along an optical axis, wherein the first lens group comprises a reflective polarizing element, a quarter-wave plate and a first lens in sequence from the first side to the second side, the second side of the reflective polarizing element is attached to the first side of the quarter-wave plate, the second side of the quarter-wave plate is attached to the first side of the first lens, at least one of the first side and the second side of the first lens, the first side and the second side of the second lens is provided with a partial reflection layer, the first side of the first lens is a concave surface, the second side of the first lens is a convex surface, the second side of the second lens is a convex surface, and the curvature radius R1 of the first side of the first lens and the curvature radius R4 of the second side of the second lens satisfy 0 < R1 / R4 < 2.

Description

Technical Field

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

[0002] The year 2022 was a year of rapid development for AR / VR devices. During this year, many companies entered the AR / VR field and laid out the AR / VR industrial chain in multiple regions. In the AR / VR field, the competition will become increasingly fierce, especially in the VR field.

[0003] Currently, the VR architecture is becoming increasingly mature, and there are more and more devices adopting the catadioptric optical system architectures of one-piece and two-piece types, gradually becoming productized. In order to maintain competitiveness, many enterprises have been laying out the catadioptric optical system architecture of three-piece type. However, from the perspective of user experience, the body of the catadioptric optical system is relatively long. When in use, the center of gravity is forward, and the experience is not good, which urgently needs to be improved. In addition, the imaging quality of the catadioptric optical system also needs to be improved, and there are problems such as the outer field of view picture being relatively blurred, which affects the experience effect of users. Summary of the Invention

[0004] The present application provides an optical system, which sequentially includes, along the optical axis from the first side to the second side: a first lens group, a second lens, and a third lens. Among them, the first lens group sequentially includes, from the first side to the second side: a reflective polarizing element, a quarter-wave plate, and a first lens, and the second side of the reflective polarizing element is adhered to the first side of the quarter-wave plate, and the second side of the quarter-wave plate and the first side of the first lens are adhered to each other; at least one of the second side of the first lens, the first side and the second side of the second lens is provided with a partial reflection layer; the first side of the first lens is concave, and the second side is convex; the second side of the second lens is convex; and the radius of curvature R1 of the first side of the first lens and the radius of curvature R4 of the second side of the second lens satisfy: 0 < R1 / R4 < 2. [[ID=I7]]

[0005] In one embodiment, the central thickness CT1 of the first lens on the optical axis and the distance TD on the optical axis from the first side of the first lens to the second side of the third lens satisfy: 0 < CT1 / TD < 0.6.

[0006] In one embodiment, the dispersion coefficient V1 of the first lens, the dispersion coefficient V2 of the second lens, the dispersion coefficient V3 of the third lens, the dispersion coefficient VRP of the reflective polarizing element, and the dispersion coefficient VQWP of the quarter-wave plate satisfy: 30 < (V1 + V2 + V3) / 3 < VRP and 30 < (V1 + V2 + V3) / 3 < VQWP.

[0007] In one embodiment, the distance Tr1rBS from the first side surface of the first lens to the surface of the lens containing the partial reflective layer on the optical axis and the distance TD from the first side surface of the first lens to the second side surface of the third lens on the optical axis satisfy: 0.3 <Tr1rBS / TD<0.7。

[0008] In one embodiment, the radius of curvature R1 of the first side surface of the first lens, the center thickness CTRP of the reflective polarizing element on the optical axis, and the center thickness CTQWP of the quarter-wave plate on the optical axis satisfy: -310 <R1 / (CTRP+CTQWP)<-40。

[0009] In one embodiment, the sum of the effective focal length f of the optical system, the distance between the first lens group and the second lens on the optical axis, and the distance between the second lens and the third lens on the optical axis, ∑AT, satisfies: 8 <f / ∑AT<150。

[0010] In one embodiment, the effective radius DT11 of the first side surface of the first lens and the distance TD between the first side surface of the first lens and the second side surface of the third lens on the optical axis satisfy: 0.6 <DT11 / TD<1.8。

[0011] In one embodiment, the radius of curvature R1 of the first side surface of the first lens, the radius of curvature RBS of the surface of the lens where the partial reflective layer is located, and the effective focal length f of the optical system satisfy: -7.0 < (R1 + RBS) / f < -1.5.

[0012] In one embodiment, the radius of curvature R1 of the first side surface of the first lens satisfies the following relationship with the effective focal length f of the optical system: -5 <R1 / f<-0.7。

[0013] In one embodiment, the distance SAG11 from the intersection of the first side surface of the first lens on the optical axis to the vertex of the maximum effective radius of the first side surface of the first lens on the optical axis, the center thickness CT1 of the first lens on the optical axis, and the aperture number Fno of the optical system satisfy: -8 <SAG11 / CT1×Fno<-4。

[0014] In one embodiment, the distance SAG22 from the intersection of the second side surface of the second lens on the optical axis to the vertex of the maximum effective radius of the second side surface of the second lens on the optical axis satisfies the following condition with respect to the radius of curvature R4 of the second side surface of the second lens: 0 <SAG22 / R4<40.5。

[0015] In one embodiment, the sum of the effective focal length f of the optical system, the maximum field of view (FOV) of the optical system, the central thicknesses of the reflective polarizing element, the quarter-wave plate, the first lens, the second lens, and the third lens along the optical axis, ∑CT, satisfies: 1.5 <f×tan(FOV / 2) / ∑CT<3.5。

[0016] In one embodiment, the first lens group has a positive optical power, the second lens has a positive optical power, and the third lens has a negative optical power and its first side is concave.

[0017] In one embodiment, the effective focal length F1 of the first lens group and the effective focal length f of the optical system satisfy: 0.8 < F1 / f < 1.2.

[0018] In one embodiment, 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: 5 ≤ (CT1 + CT2) / CT3 < 11.

[0019] In one embodiment, the third lens has a positive optical power and its second side is convex.

[0020] In one embodiment, the central thickness CT3 of the third lens on the optical axis, the effective focal length f of the optical system, and the maximum field angle FOV of the optical system satisfy: 0.2 < CT3 / (f × tan(FOV / 2)) < 0.5.

[0021] In one embodiment, the radius of curvature R6 of the second side of the third lens and the effective focal length f3 of the third lens satisfy: -1.1 < R6 / f3 < -0.1.

[0022] In one embodiment, the dispersion coefficient V1 of the first lens, the dispersion coefficient V2 of the second lens, the effective focal length f of the optical system, and the effective focal length F1 of the first lens group satisfy: 2 < (V1 - V2) × f / F1 < 5.

[0023] On the other hand, the present application also provides an optical device, which includes the optical system provided by at least one of the above embodiments.

[0024] The optical system provided by the present application is a three - lens catadioptric optical system. By utilizing the phase - addition function of the quarter - wave plate for polarized light, the beam - splitting function of the reflective polarizing element, and the reflection function of the partial reflection layer, the folding effect of the imaging light path is achieved, which can better compress the height of the body and improve the imaging quality. At the same time, the surface shape and radius of curvature of the lenses are reasonably set. The first side of the first lens is concave, the second side is convex, the second side of the second lens is convex, and the radius of curvature R1 of the first side of the first lens and the radius of curvature R4 of the second side of the second lens satisfy: 0 < R1 / R4 < 2, which is beneficial to reducing the angle between the light ray and the lens surface and reducing aberration, thereby improving the system performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments, taken in conjunction with the accompanying drawings. In the drawings:

[0026] Figure 1 The diagram shows the structural layout of an optical system according to this application and a schematic diagram of the optical path refracting.

[0027] Figure 2 A schematic diagram of the structure of the optical system according to Embodiment 1 of this application is shown;

[0028] Figures 3A to 3C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 1 of this application are shown respectively.

[0029] Figure 4 A schematic diagram of the structure of the optical system according to Embodiment 2 of this application is shown;

[0030] Figures 5A to 5C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 2 of this application are shown respectively.

[0031] Figure 6 A schematic diagram of the structure of the optical system according to Embodiment 3 of this application is shown;

[0032] Figures 7A to 7C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 3 of this application are shown respectively.

[0033] Figure 8 A schematic diagram of the structure of the optical system according to Embodiment 4 of this application is shown;

[0034] Figures 9A to 9C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 4 of this application are shown respectively.

[0035] Figure 10 A schematic diagram of the structure of the optical system according to Embodiment 5 of this application is shown;

[0036] Figures 11A to 11C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 5 of this application are shown respectively.

[0037] Figure 12 A schematic diagram of the structure of the optical system according to Embodiment 6 of this application is shown; and

[0038] Figures 13A to 13C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 6 of this application are shown respectively. Detailed Implementation

[0039] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0040] It should be noted that in this specification, the terms "first," "second," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens, and the second lens may also be referred to as the first lens.

[0041] 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.

[0042] In this paper, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region.

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

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0046] The features, principles and other aspects of this application will be described in detail below with reference to the accompanying drawings and embodiments.

[0047] An optical system according to an exemplary embodiment of this application includes, sequentially from the first side to the second side along the optical axis: a first lens group, a second lens, and a third lens. The first lens group, from the first side to the second side, includes, in sequence: a reflective polarizing element, a quarter-wave plate, and a first lens. The second side of the reflective polarizing element is attached to the first side of the quarter-wave plate, and the second side of the quarter-wave plate is attached to the first side of the first lens. At least one of the second side of the first lens, the first side of the second lens, and the second side of the second lens has a partially reflective layer. This application, by attaching a reflective polarizing plate and a quarter-wave plate to the first side of the first lens, can change the polarization state of polarized light, so that the light is reflected when it first passes through the first side of the first lens, and transmitted when it passes through the first side of the first lens a second time. The partially reflective layer on at least one of the second side of the first lens, the first side of the second lens, and the second side of the second lens, combined with the polarizing film on the first side of the first lens, allows for folding of the optical path and compression of the length of the optical system.

[0048] The optical system provided in this application is a three-piece catadioptric optical system. It utilizes the phase-adding function of a quarter-wave plate, the beam-splitting function of a reflective polarizing element, and the reflection function of a partial reflective layer to achieve a folding effect in the imaging optical path. This can better compress the height of the body and improve the imaging quality.

[0049] In an exemplary embodiment, the first side surface of the first lens is concave, and the second side surface is convex.

[0050] In an exemplary embodiment, the second side surface of the second lens is a convex surface.

[0051] In an exemplary embodiment, the radius of curvature R1 of the first side surface of the first lens and the radius of curvature R4 of the second side surface of the second lens satisfy: 0 <R1 / R4<2。

[0052] An optical system according to an exemplary embodiment of the present application sequentially includes, along the optical axis, from the first side to the second side: a first lens group, a second lens, and a third lens. Among them, the first lens group sequentially includes, from the first side to the second side: a reflective polarizing element, a quarter-wave plate, and a first lens. The second side surface of the reflective polarizing element is adhered to the first side surface of the quarter-wave plate, and the second side surface of the quarter-wave plate is adhered to the first side surface of the first lens; a partial reflection layer is provided on at least one of the second side surface of the first lens, the first side surface and the second side surface of the second lens; the first side surface of the first lens is concave, and the second side surface is convex; the second side surface of the second lens is convex; and the radius of curvature R1 of the first side surface of the first lens and the radius of curvature R4 of the second side surface of the second lens satisfy: 0 < R1 / R4 < 2. By attaching a reflective polarizer and a quarter-wave plate to the first side surface of the first lens, the polarization state of polarized light can be changed, so that the light is reflected when passing through the first side surface of the first lens for the first time and transmitted when passing through the first side surface of the first lens for the second time; a partial reflection layer is provided on at least one of the second side surface of the first lens, the first side surface and the second side surface of the second lens. Combining with the polarization film on the first side surface of the first lens, the optical path can be folded and the length of the optical system can be compressed. At the same time, the surface types and radii of curvature of the first lens and the second lens are reasonably set. The first side surface of the first lens is concave, the second side surface is convex, and the second side surface of the second lens is convex. With the above lens shapes, the angle between the light and the lens surface is reduced, which is beneficial to reducing aberration and thus improving the system performance.

[0053] In an exemplary embodiment, the radius of curvature R1 of the first side surface of the first lens and the radius of curvature R4 of the second side surface of the second lens may further satisfy: 0.5 < R1 / R4 < 2.

[0054] In an exemplary embodiment, the optical system further includes a display disposed on the second side of the third lens. The optical system can be applied to, for example, a VR device. The first side can be, for example, the human eye side, and the second side can be, for example, the display side. The image light on the display screen finally projects onto the user's eyes after multiple refractions and reflections through the third lens, the second lens, the first lens, the quarter-wave plate, and the reflective polarizing element, etc.

[0055] Reference Figure 1The optical system, along the optical axis from the first side to the second side, consists of 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 a display S9. The reflective polarizing element RP has a first side surface S1 and a second side surface S2; the quarter-wave plate QWP has a first side surface S2 and a second side surface S3; and the first lens E1 has a first side surface S3 and a second side surface S4. Specifically, S2 is the shared surface of the second side surface of the reflective polarizing element RP and the first side surface of the quarter-wave plate QWP, and the second side surface of the reflective polarizing element RP is in contact with the first side surface of the quarter-wave plate QWP; S3 is the shared surface of the second side surface of the quarter-wave plate QWP and the first side surface of the first lens E1, and the second side surface of the quarter-wave plate QWP is in contact with the first side surface of the first lens E1. The second lens E2 has a first side surface S5 and a second side surface S6. The third lens E3 has a first side surface S7 and a second side surface S8.

[0056] In an exemplary embodiment, the optical system further includes a partially reflective layer disposed on at least one of the second side surface of the first lens and the first and second side surfaces of the second lens. The partially reflective layer has a semi-transparent, semi-reflective function. In some embodiments, such as... Figure 2 and Figure 4 As shown, a partially reflective layer is disposed on the second side of the first lens. Light emitted from the display screen passes sequentially through the third lens, the second lens, the first lens, and the quarter-wave plate QWP to reach the reflective polarizing element RP. At the reflective polarizing element RP, the light is reflected and passes again through the quarter-wave plate QWP and the first lens. Subsequently, the light beam is reflected again at the partially reflective layer on the second side of the first lens and passes sequentially through the first lens, the quarter-wave plate QWP, and the reflective polarizing element RP, passing through the aperture STO and finally exiting towards the viewer's eye. In other embodiments, such as... Figure 6 , Figure 8 , Figure 10 and Figure 12 As shown, a partial reflective layer is provided on the second side of the second lens. The light emitted from the display screen passes sequentially through the third lens, the second lens, the first lens, and the quarter-wave plate QWP to reach the reflective polarizing element RP. It is reflected at the reflective polarizing element RP and passes through the quarter-wave plate QWP and the first lens again to reach the second lens. Subsequently, the light beam is reflected again at the partial reflective layer on the second side of the second lens and passes sequentially through the second lens, the first lens, the quarter-wave plate QWP, and the reflective polarizing element RP. It passes through the aperture STO and finally exits towards the human eye.

[0057] In an exemplary embodiment, a reflective polarizing element and a quarter-wave plate are combined, and the required structure can be obtained through a single attaching process operation instead of attaching them in two separate steps, reducing the angular position error caused by attaching and improving the imaging quality.

[0058] According to the optical system of the exemplary embodiment of the present application, by setting a reflective polarizing element, light of a certain polarization direction can be reflected while light orthogonal to this polarization direction can be transmitted; by setting a quarter-wave plate, the polarization state of light can be changed; and by setting a partial reflection layer on at least one of the second side surface of the first lens, the first side surface and the second side surface of the second lens, reflection and transmission can be achieved, enabling the system optical path to be refracted and reflected, which is beneficial for shortening the length of the VR device.

[0059] In an exemplary embodiment, the optical system of the present application can satisfy: 0 < CT1 / TD < 0.6, where CT1 is the central thickness of the first lens on the optical axis, and TD is the distance on the optical axis from the first side surface of the first lens to the second side surface of the third lens. Satisfying 0 < CT1 / TD < 0.6, by controlling the ratio of the central thickness of the first lens to the axial distance from the first lens to the third lens, the structural strength of the first lens is ensured, which is beneficial for the assembly of the optical system.

[0060] In an exemplary embodiment, the optical system of the present application can satisfy: 30 < (V1 + V2 + V3) / 3 < VRP and 30 < (V1 + V2 + V3) / 3 < VQWP, where V1 is the dispersion coefficient of the first lens, V2 is the dispersion coefficient of the second lens, V3 is the dispersion coefficient of the third lens, VRP is the dispersion coefficient of the reflective polarizing element, and VQWP is the dispersion coefficient of the quarter-wave plate. Satisfying 30 < (V1 + V2 + V3) / 3 < VRP and 30 < (V1 + V2 + V3) / 3 < VQWP, by controlling the dispersion coefficients of the three lenses and the dispersion coefficients of the reflective polarizing element and the quarter-wave plate, the dispersion coefficients of the reflective polarizing element and the quarter-wave plate are made larger, and correspondingly, the refractive index is smaller, which is beneficial for reducing the influence of the thickness change of the reflective polarizing element and the quarter-wave plate on the optical system.

[0061] In an exemplary embodiment, the optical system of the present application can satisfy: 0.3 < Tr1rBS / TD < 0.7, where Tr1rBS is the distance on the optical axis from the first side surface of the first lens to the surface of the lens where the partial reflection layer is located, and TD is the distance on the optical axis from the first side surface of the first lens to the second side surface of the third lens. Satisfying 0.3 < Tr1rBS / TD < 0.7, by controlling the axial distance from the first side surface of the first lens to the surface of the lens where the partial reflection layer is located and the axial distance from the first side surface of the first lens to the second side surface of the third lens, and making their ratio larger, the light refraction and reflection are longer, which is beneficial for shortening the length of the optical system.

[0062] In an exemplary embodiment, the optical system of the present application can satisfy the condition -310 < R1 / (CTRP + CTQWP) < -40, where R1 is the radius of curvature of the first surface of the first lens, CTRP is the central thickness of the reflective polarizing element on the optical axis, and CTQWP is the central thickness of the quarter-wave plate on the optical axis. Satisfying -310 < R1 / (CTRP + CTQWP) < -40, by controlling the ratio of the radius of curvature of the first surface of the first lens to the sum of the central thicknesses of the reflective polarizing element and the quarter-wave plate to be relatively large, it is beneficial to control the degree of curvature of the first surface of the first lens, and further beneficial to the degree of surface adhesion of the reflective polarizing element and the quarter-wave plate.

[0063] In an exemplary embodiment, the optical system of the present application can satisfy: 8 < f / ∑AT < 150, where f is the effective focal length of the optical system, and ∑AT is the sum of the axial distances between the first lens group and the second lens and between the second lens and the third lens on the optical axis. Satisfying 8 < f / ∑AT < 150, by controlling the ratio of the effective focal length of the optical system to the axial distance between the three lenses, the lens spacing is made smaller, which is beneficial to reducing the ghost image intensity between the lenses.

[0064] In an exemplary embodiment, the optical system of the present application can satisfy: 0.6 < DT11 / TD < 1.8, where DT11 is the effective radius of the first surface of the first lens, and TD is the axial distance from the first surface of the first lens to the second surface of the third lens. Satisfying 0.6 < DT11 / TD < 1.8, by controlling the ratio of the effective radius of the first surface of the first lens to the axial distance from the first surface of the first lens to the second surface of the third lens, that is, controlling the ratio of the aperture to the thickness of the lens, the strength of the lens is ensured, which is beneficial to the reliability of the optical system.

[0065] In an exemplary embodiment, the optical system of the present application can satisfy: -7.0 < (R1 + RBS) / f < -1.5, where R1 is the radius of curvature of the first surface of the first lens, RBS is the radius of curvature of the surface of the lens where the partial reflection layer is located, and f is the effective focal length of the optical system. Satisfying -7.0 < (R1 + RBS) / f < -1.5, by controlling the ratio of the sum of the radius of curvature of the first surface of the first lens and the radius of curvature of the surface of the lens where the partial reflection layer is located to the effective focal length of the optical system, the angle between the light ray and the surface of the first lens can be reduced at the first surface of the first lens, effectively reducing the possible aberration here and improving the imaging quality of the optical system.

[0066] In an exemplary embodiment, the optical system of the present application can satisfy: -5 < R1 / f < -0.7, where R1 is the radius of curvature of the first side of the first lens, and f is the effective focal length of the optical system. Satisfying -5 < R1 / f < -0.7, by controlling the ratio of the radius of curvature of the first side of the first lens to the effective focal length of the optical system, on the one hand, making the ratio negative is beneficial for controlling the first side of the first lens to be concave, and on the other hand, making the ratio smaller results in a smaller concave curvature, enabling light to be incident perpendicularly on the first side of the first lens, thereby reducing the aberration introduced by the first lens.

[0067] In an exemplary embodiment, the optical system of the present application can satisfy: -8 < SAG11 / CT1×Fno < -4, where SAG11 is the distance on the optical axis from the intersection point of the first side of the first lens on the optical axis to the vertex of the maximum effective radius of the first side of the first lens on the optical axis, CT1 is the central thickness of the first lens on the optical axis, and Fno is the f-number of the optical system. Satisfying -8 < S S SAG11 / CT1×Fno < -4 restricts the ratio of the sagitta of the first side of the first lens to the central thickness of the first lens, which is beneficial for ensuring the molding of the first lens.

[0068] In an exemplary embodiment, the optical system of the present application can satisfy: 0 < SAG22 / R4 < 40.5, where SAG22 is the distance on the optical axis from the intersection point of the second side of the second lens on the optical axis to the vertex of the maximum effective radius of the second side of the second lens on the optical axis, and R4 is the radius of curvature of the second side of the second lens. Satisfying 0 < SAG22 / R4 < 40.5, by controlling the sagitta of the second side of the second lens and the radius of curvature of the second side of the second lens, the effective aperture of the second lens is indirectly controlled, which is beneficial for the miniaturization of the optical system.

[0069] [[ID=**9**]]In an exemplary embodiment, the optical system of the present application can satisfy: 1.5 < f×tan(FOV / 2) / ∑CT < 3.5, where f is the effective focal length of the optical system, FOV is the maximum field of view angle of the optical system, and ∑CT is the sum of the central thicknesses of the reflective polarizing element, quarter-wave plate, first lens, second lens, and third lens on the optical axis. f×tan(FOV / 2) is the screen size. By controlling the screen size and the sum of the central thicknesses of the components in the optical system to make the ratio within a certain range, that is, satisfying 1.5 < f×tan(FOV / 2) / ∑CT < 3.5, on the premise of a certain screen size, the thickness of the optical system is effectively controlled, which is beneficial for reducing the size of the optical system.

[0070] In an exemplary embodiment, the first lens group has a positive optical power, the second lens has a positive optical power, and the third lens has a negative optical power and its first side is concave. Both the first lens group and the second lens have positive optical powers, which is conducive to light convergence and compression of the light height; the third lens has a negative optical power, and combined with the first lens group and the second lens, the positive and negative optical powers are matched, which is conducive to correcting the system aberration.

[0071] In an exemplary embodiment, the third lens has a positive optical power and its second side is convex. Making the optical power of the third lens positive and its second side convex is conducive to further compressing the light height, thereby facilitating the reduction of the screen size.

[0072] In an exemplary embodiment, the optical system of the present application can satisfy: 0.8 < F1 / f < 1.2, where F1 is the effective focal length of the first lens group and f is the effective focal length of the optical system. Satisfying 0.8 < F1 / f < 1.2, by controlling the ratio of the effective focal length of the first lens group to the effective focal length of the optical system, the optical power of the first lens group is positive and its value is close to the system focal length, which is conducive to the first lens group converging light, thereby facilitating the reduction of the size of the subsequent lens group.

[0073] In an exemplary embodiment, the optical system of the present application can satisfy: 5 ≤ (CT1 + CT2) / CT3 < 11, where CT1 is the central thickness of the first lens on the optical axis, CT2 is the central thickness of the second lens on the optical axis, and CT3 is the central thickness of the third lens on the optical axis. Satisfying 5 ≤ (CT1 + CT2) / CT3 < 11, by controlling the ratio of the central thicknesses of the first lens and the second lens on the optical axis to the central thickness of the third lens on the optical axis to be relatively large, the optical path folding length is ensured, which is conducive to reducing the length of the optical system.

[0074] In an exemplary embodiment, the optical system of the present application can satisfy: 0.2 < CT3 / (f × tan(FOV / 2)) < 0.5, where CT3 is the central thickness of the third lens on the optical axis, f is the effective focal length of the optical system, and FOV is the maximum field angle of the optical system. f × tan(FOV / 2) is the screen size. By controlling the ratio of the central thickness of the third lens to the screen size to be relatively small, the distance from the first lens to the third lens is indirectly controlled, thereby restricting the optical path folding length.

[0075] In an exemplary embodiment, the optical system of the present application can satisfy: -1.1 < R6 / f3 < -0.1, where R6 is the radius of curvature of the second side of the third lens and f3 is the effective focal length of the third lens. Satisfying -1.1 < R6 / f3 < -0.1, by controlling the ratio of the radius of curvature of the second side of the third lens to the effective focal length of the third lens, the shape of the third lens is effectively restricted, which is conducive to the shaping of the third lens.

[0076] In an exemplary embodiment, the optical system of this application satisfies: 2 < (V1-V2) × f / F1 < 5, where V1 is the dispersion coefficient of the first lens, V2 is the dispersion coefficient of the second lens, f is the effective focal length of the optical system, and F1 is the effective focal length of the first lens group. Satisfying 2 < (V1-V2) × f / F1 < 5, by controlling the dispersion coefficients of the first and second lenses, the effective focal length of the first lens group, and the effective focal length of the optical system, helps to constrain monochromatic aberration and chromatic aberration of the system, thereby improving the imaging quality of the system.

[0077] In an exemplary embodiment, the optical system of this application may include at least one aperture stop. The aperture stop can constrain the optical path and control the light intensity. The aperture stop can be positioned at an appropriate location within the optical system; for example, the aperture stop can be located on a first side of the first lens.

[0078] In an exemplary embodiment, the effective focal length f of the optical system can be, for example, in the range of 25.5 mm to 33.8 mm, the focal length F1 of the first lens group can be, for example, in the range of -229.0 mm to 9656.0 mm, the effective focal length f2 of the second lens can be, for example, in the range of -940.0 mm to 322.0 mm, and the effective focal length f3 of the third lens can be, for example, in the range of -474.0 mm to 348.0 mm.

[0079] According to some embodiments of this application, the optical system of this application is a small-volume optical system with high-definition imaging quality. In application, the optical system according to exemplary embodiments of this application can be applied to VR devices. By reasonably setting the effective focal length, maximum field of view, entrance pupil diameter, and lens parameters such as center thickness, refractive index, Abbe number, and radius of curvature of the optical system, and by reasonably setting the aperture parameters, the wide-angle purpose of the VR device can be met, as well as the chromatic aberration of the system can be corrected, thereby improving the system's imaging quality. By setting supporting elements between the lenses, the lens processing and forming performance can be improved, the lens sensitivity can be reduced, the assembly yield can be increased, and the miniaturization goal of VR equipment can be met while ensuring the performance of the optical system.

[0080] Specific embodiments of the optical system applicable to the above-described embodiments are further described below with reference to the accompanying drawings.

[0081] Example 1

[0082] The following is for reference Figures 2 to 3C The optical system according to Embodiment 1 of this application is described. Figure 2 A schematic diagram of the structure of an optical system according to Embodiment 1 of this application is shown.

[0083] like Figure 2As shown, the optical system includes, in sequence from the first side to the second side along the optical axis: aperture STO, reflective polarizing element RP, quarter-wave plate QWP, first lens E1, second lens E2, third lens E3, and display S9.

[0084] like Figure 2 As shown, the reflective polarizing element RP has a first side surface S1 and a second side surface S2, the quarter-wave plate QWP has a first side surface S2 and a second side surface S3, and the first lens E1 has a first side surface S3 and a second side surface S4. Specifically, S2 is a shared surface between the second side surface of the reflective polarizing element RP and the first side surface of the quarter-wave plate QWP, and the second side surface of the reflective polarizing element RP is in contact with the first side surface of the quarter-wave plate QWP; S3 is a shared surface between the second side surface of the quarter-wave plate QWP and the first side surface of the first lens E1, and the second side surface of the quarter-wave plate QWP is in contact with the first side surface of the first lens E1. The second lens E2 has a first side surface S5 and a second side surface S6. The third lens E3 has a first side surface S7 and a second side surface S8. The optical system also includes a partial reflective layer BS (not shown) disposed on the second side surface S4 of the first lens E1.

[0085] Table 1 shows the basic parameters of the optical system of Embodiment 1, where the units for radius of curvature and thickness are millimeters (mm). Table 1 only lists the correspondence between surface numbers and some components as an example. Due to the issue of shared surfaces between adjacent components, it is inconvenient to mark all components at the locations of shared surfaces in Table 1.

[0086]

[0087]

[0088] Table 1

[0089] For example, when the optical system is applied to a VR device, the first side can be, for example, the eye side, and the second side can be, for example, the display side. Light from the display S9 sequentially passes through the third lens E3, the second lens E2, the first lens E1, and the quarter-wave plate QWP to reach the reflective polarizing element RP. It is reflected at the reflective polarizing element RP and passes through the quarter-wave plate QWP and the first lens E1 again. Subsequently, the light beam is reflected again at the partial reflective layer BS on the second side surface S4 of the first lens E1 and sequentially passes through the first lens E1, the quarter-wave plate QWP, and the reflective polarizing element RP, passes through the aperture STO, and finally exits towards the eye side. In an exemplary embodiment, the partial reflective layer can be a semi-transparent, semi-reflective film layer deposited on the second side surface S4 of the first lens E1. In this example, the partial reflective layer can be deposited in the region of the second side surface S4 of the first lens E1 that is away from the optical axis.

[0090] In Example 1, the first and second sides of the reflective polarizing element RP, the quarter-wave plate QWP, the first lens E1, the second lens E2, and the third lens E3 are all aspherical. The surface shape x of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0091]

[0092] Where z is the depth of the aspherical surface (the perpendicular distance between a point on the aspherical surface at a distance y from the optical axis and a tangent plane at the vertex on the optical axis of the aspherical surface); c is the curvature of the vertex of the aspherical surface; and K is the cone coefficient. r is the radial distance; n The normalized radius is u; u is r / r n ;a m Q of order m con coefficient; Q m con Q of order m con Polynomials. Table 2 below gives the higher-order coefficients a0, a1, a2 and a3 that can be used for each aspherical mirror S1, S2, S3, S4, S5, S6, S7 and S8 in Example 1.

[0093] Face number <![CDATA[a0]]> <![CDATA[a1]]> <![CDATA[a2]]> <![CDATA[a3]]> S1 -9.6015E-02 -2.8221E-02 3.0950E-02 2.2307E-03 S2 -9.6015E-02 -2.8221E-02 3.0950E-02 2.2307E-03 S3 -9.6015E-02 -2.8221E-02 3.0950E-02 2.2307E-03 S4 -1.7536E-01 2.1371E-02 1.4276E-02 -2.2234E-03 S5 -3.8312E-01 1.7814E-01 -8.7838E-02 -1.2893E-02 S6 -2.1499E-01 4.7951E-01 2.2208E-01 -7.7146E-02 S7 1.6150E-01 1.6404E-01 -3.0321E-02 -7.0093E-02 S8 -3.1354E-02 3.8923E-01 -1.4739E-01 -1.6540E-02

[0094] Table 2

[0095] Table 3 provides the values ​​of parameters such as the maximum field of view (FOV), aperture number (Fno), effective focal length (f) of the optical system in Example 1, effective focal length (F1) of the first lens group (including the reflective polarizing element RP, the quarter-wave plate (QWP), and the first lens (E1), effective focal length (f2) of the second lens (E2), and effective focal length (f3) of the third lens (E3).

[0096]

[0097] Table 3

[0098] Figure 3A The on-axis chromatic aberration curve of the optical system of Embodiment 1 is shown, which represents the deviation of light of different wavelengths from the convergence focal point after passing through the lens. Figure 3B 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 3C The distortion curves of the optical system of Example 1 are shown, representing the distortion magnitude values ​​corresponding to different half-field angles. According to... Figures 3A to 3C It can be seen that the optical system given in Example 1 can achieve good imaging quality.

[0099] Example 2

[0100] The following is for reference Figures 4 to 5C An optical system according to Embodiment 2 of this application is described. In this embodiment and the following embodiments, for the sake of brevity, some descriptions similar to those in Embodiment 1 will be omitted. Figure 4 A schematic diagram of the structure of an optical system according to Embodiment 2 of this application is shown.

[0101] like Figure 4 As shown, the optical system includes, in sequence from the first side to the second side along the optical axis: aperture STO, reflective polarizing element RP, quarter-wave plate QWP, first lens E1, second lens E2, third lens E3, and display S9.

[0102] like Figure 4 As shown, the reflective polarizing element RP has a first side surface S1 and a second side surface S2, the quarter-wave plate QWP has a first side surface S2 and a second side surface S3, and the first lens E1 has a first side surface S3 and a second side surface S4. Specifically, S2 is a shared surface between the second side surface of the reflective polarizing element RP and the first side surface of the quarter-wave plate QWP, and the second side surface of the reflective polarizing element RP is in contact with the first side surface of the quarter-wave plate QWP; S3 is a shared surface between the second side surface of the quarter-wave plate QWP and the first side surface of the first lens E1, and the second side surface of the quarter-wave plate QWP is in contact with the first side surface of the first lens E1. The second lens E2 has a first side surface S5 and a second side surface S6. The third lens E3 has a first side surface S7 and a second side surface S8. The optical system also includes a partial reflective layer BS (not shown) disposed on the second side surface S4 of the first lens E1.

[0103] Table 4 shows the basic parameters of the optical system of Embodiment 2, where the units for radius of curvature and thickness are millimeters (mm). Table 4 only lists the correspondence between surface numbers and some components on a partial basis. Due to the issue of shared surfaces between adjacent components, it is inconvenient to mark all components at the locations of shared surfaces in Table 4. Table 5 shows the higher-order coefficients that can be used for each aspherical mirror in Embodiment 2, where each aspherical surface shape can be defined by formula (1) given in Embodiment 1 above.

[0104]

[0105]

[0106] Table 4

[0107] Face number <![CDATA[a0]]> <![CDATA[a1]]> <![CDATA[a2]]> <![CDATA[a3]]> S1 2.2678E-01 4.8368E-02 -3.8900E-03 -1.4582E-02 S2 2.2678E-01 4.8368E-02 -3.8900E-03 -1.4582E-02 S3 2.2678E-01 4.8368E-02 -3.8900E-03 -1.4582E-02 S4 1.7070E-01 2.8904E-02 -1.8839E-02 -1.5550E-03 S5 1.7934E-01 4.5977E-02 -6.8587E-02 2.6923E-02 S6 -1.9511E-01 6.7312E-02 1.4206E-01 5.0502E-02 S7 -4.3142E-02 8.5068E-03 2.4669E-01 1.2067E-01 S8 -1.1994E-01 2.2683E-01 2.6295E-02 2.7582E-02

[0108] Table 5

[0109] For example, when the optical system is applied to a VR device, the first side can be, for example, the eye side, and the second side can be, for example, the display side. Light from the display S9 sequentially passes through the third lens E3, the second lens E2, the first lens E1, and the quarter-wave plate QWP to reach the reflective polarizing element RP. It is reflected at the reflective polarizing element RP and passes through the quarter-wave plate QWP and the first lens E1 again. Subsequently, the light beam is reflected again at the partial reflective layer BS on the second side surface S4 of the first lens E1 and sequentially passes through the first lens E1, the quarter-wave plate QWP, and the reflective polarizing element RP, passes through the aperture STO, and finally exits towards the eye side. In an exemplary embodiment, the partial reflective layer can be a semi-transparent, semi-reflective film layer deposited on the second side surface S4 of the first lens E1. In this example, the partial reflective layer can be deposited in the region of the second side surface S4 of the first lens E1 that is away from the optical axis.

[0110] Table 6 provides the values ​​of parameters such as the maximum field of view (FOV), aperture number (Fno), effective focal length (f), effective focal length (F1) of the first lens group (including the reflective polarizing element RP, the quarter-wave plate QWP, and the first lens E1), effective focal length (f2) of the second lens E2, and effective focal length (f3) of the third lens E3 in Example 2.

[0111]

[0112] Table 6

[0113] Figure 5A The on-axis chromatic aberration curve of the optical system of Embodiment 2 is shown, which represents the deviation of light of different wavelengths from the convergence focal point after passing through the lens. Figure 5B 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 5C The distortion curves of the optical system in Example 2 are shown, representing the distortion magnitudes corresponding to different half-field angles. According to... Figures 5A to 5C It can be seen that the optical system given in Example 2 can achieve good imaging quality.

[0114] Example 3

[0115] The following is for reference Figures 6 to 7C An optical system according to Embodiment 3 of this application is described. Figure 6 A schematic diagram of the structure of an optical system according to Embodiment 3 of this application is shown.

[0116] like Figure 6 As shown, the optical system includes, in sequence from the first side to the second side along the optical axis: aperture STO, reflective polarizing element RP, quarter-wave plate QWP, first lens E1, second lens E2, third lens E3, and display S9.

[0117] like Figure 6 As shown, the reflective polarizing element RP has a first side surface S1 and a second side surface S2, the quarter-wave plate QWP has a first side surface S2 and a second side surface S3, and the first lens E1 has a first side surface S3 and a second side surface S4. Specifically, S2 is a shared surface between the second side surface of the reflective polarizing element RP and the first side surface of the quarter-wave plate QWP, and the second side surface of the reflective polarizing element RP is in contact with the first side surface of the quarter-wave plate QWP; S3 is a shared surface between the second side surface of the quarter-wave plate QWP and the first side surface of the first lens E1, and the second side surface of the quarter-wave plate QWP is in contact with the first side surface of the first lens E1. The second lens E2 has a first side surface S5 and a second side surface S6. The third lens E3 has a first side surface S7 and a second side surface S8. The optical system also includes a partially reflective layer BS (not shown) disposed on the second side surface S6 of the second lens E2.

[0118] Table 7 shows the basic parameters of the optical system of Embodiment 3, where the units for radius of curvature and thickness are millimeters (mm). Table 7 only lists the correspondence between surface numbers and some components on a partial basis. Due to the issue of shared surfaces between adjacent components, it is inconvenient to mark all components at the locations of shared surfaces in Table 7. Table 8 shows the higher-order coefficients that can be used for each aspherical mirror in Embodiment 3, where each aspherical surface shape can be defined by formula (1) given in Embodiment 1 above.

[0119] surface Component Name Surface type radius of curvature thickness Refractive index Abbe number Refraction / Reflection spherical endless endless STO Stabilizer (STO) spherical endless 22.4497 refraction S1 Reflective polarizing element (RP) aspherical -52.3329 0.2000 1.50 57.00 refraction S2 Quarter-wave plate (QWP) aspherical -52.3329 0.2000 1.50 57.00 refraction S3 First lens (E1) aspherical -52.3329 5.0189 1.48 60.00 refraction S4 aspherical -44.7519 1.5303 refraction S5 Second lens (E2) aspherical -38.8319 1.8496 1.68 19.00 refraction S6 Partial reflective element (BS) aspherical -42.1501 -1.8496 1.68 19.00 reflection S5 aspherical -38.8319 -1.5303 refraction S4 aspherical -44.7519 -5.0189 1.48 60.00 refraction S3 Quarter-wave plate (QWP) aspherical -52.3329 -0.2000 1.50 57.00 refraction S2 aspherical -52.3329 0.2000 1.50 57.00 reflection S3 aspherical -52.3329 5.0189 refraction S4 aspherical -44.7519 1.5303 refraction S5 Second lens (E2) aspherical -38.8319 1.8496 1.68 19.00 refraction S6 aspherical -42.1501 0.1000 refraction S7 Third lens (E3) aspherical 65.3211 19.3368 1.48 59.83 refraction S8 aspherical -81.1681 2.8335 refraction S9 Display (S9) spherical endless

[0120] Table 7

[0121]

[0122]

[0123] Table 8

[0124] For example, when the optical system is applied to a VR device, the first side can be, for example, the eye side, and the second side can be, for example, the display side. Light from the display S9 sequentially passes through the third lens E3, the second lens E2, the first lens E1, and the quarter-wave plate QWP to reach the reflective polarizing element RP. It is reflected at the reflective polarizing element RP and passes again through the quarter-wave plate QWP and the first lens E1 to reach the second lens E2. Subsequently, the light beam is reflected again at the partial reflective layer BS on the second side surface S6 of the second lens E2 and sequentially passes through the second lens E2, the first lens E1, the quarter-wave plate QWP, and the reflective polarizing element RP, passes through the aperture STO, and finally exits towards the eye side. In an exemplary embodiment, the partial reflective layer can be a semi-transparent, semi-reflective film layer deposited on the second side surface S6 of the second lens E2. In this example, the partial reflective layer can be deposited in the region of the second side surface S6 of the second lens E2 that is away from the optical axis.

[0125] Table 9 provides the values ​​of parameters such as the maximum field of view (FOV), aperture number (Fno), effective focal length (f) of the optical system in Example 3, effective focal length (F1) of the first lens group (including the reflective polarizing element RP, the quarter-wave plate QWP, and the first lens E1), effective focal length (f2) of the second lens E2, and effective focal length (f3) of the third lens E3.

[0126]

[0127] Table 9

[0128] Figure 7A The on-axis chromatic aberration curve of the optical system of Embodiment 3 is shown, which represents the deviation of light of different wavelengths from the convergence focal point after passing through the lens. Figure 7B 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 7C The distortion curves of the optical system in Example 3 are shown, representing the distortion magnitudes corresponding to different half-field angles. According to... Figures 7A to 7C It can be seen that the optical system given in Example 3 can achieve good imaging quality.

[0129] Example 4

[0130] The following is for reference Figures 8 to 9C An optical system according to Embodiment 4 of this application is described. Figure 8 A schematic diagram of the structure of an optical system according to Embodiment 4 of this application is shown.

[0131] like Figure 8As shown, the optical system includes, in sequence from the first side to the second side along the optical axis: aperture STO, reflective polarizing element RP, quarter-wave plate QWP, first lens E1, second lens E2, third lens E3, and display S9.

[0132] like Figure 8 As shown, the reflective polarizing element RP has a first side surface S1 and a second side surface S2, the quarter-wave plate QWP has a first side surface S2 and a second side surface S3, and the first lens E1 has a first side surface S3 and a second side surface S4. Specifically, S2 is a shared surface between the second side surface of the reflective polarizing element RP and the first side surface of the quarter-wave plate QWP, and the second side surface of the reflective polarizing element RP is in contact with the first side surface of the quarter-wave plate QWP; S3 is a shared surface between the second side surface of the quarter-wave plate QWP and the first side surface of the first lens E1, and the second side surface of the quarter-wave plate QWP is in contact with the first side surface of the first lens E1. The second lens E2 has a first side surface S5 and a second side surface S6. The third lens E3 has a first side surface S7 and a second side surface S8. The optical system also includes a partially reflective layer BS (not shown) disposed on the second side surface S6 of the second lens E2.

[0133] Table 10 shows the basic parameters of the optical system of Embodiment 4, where the units for radius of curvature and thickness are millimeters (mm). Table 10 only lists the correspondence between surface numbers and some components on a partial basis. Due to the issue of shared surfaces between adjacent components, it is inconvenient to mark all components at the locations of shared surfaces in Table 10. Table 11 shows the higher-order coefficients that can be used for each aspherical mirror in Embodiment 4, where each aspherical surface shape can be defined by formula (1) given in Embodiment 1 above.

[0134] surface Component Name Surface type radius of curvature thickness Refractive index Abbe number Refraction / Reflection spherical endless endless STO Stabilizer (STO) spherical endless 17.9275 refraction S1 Reflective polarizing element (RP) aspherical -87.3615 0.2000 1.50 57.00 refraction S2 Quarter-wave plate (QWP) aspherical -87.3615 0.2000 1.50 57.00 refraction S3 First lens (E1) aspherical -87.3615 2.4764 1.68 19.05 refraction S4 aspherical -226.9014 0.3387 refraction S5 Second lens (E2) aspherical -190.2984 8.2212 1.49 55.39 refraction S6 Partial reflective element (BS) aspherical -52.9129 -8.2212 1.49 55.39 reflection S5 aspherical -190.2984 -0.3387 refraction S4 aspherical -226.9014 -2.4764 1.68 19.05 refraction S3 Quarter-wave plate (QWP) aspherical -87.3615 -0.2000 1.50 57.00 refraction S2 aspherical -87.3615 0.2000 1.50 57.00 reflection S3 aspherical -87.3615 2.4764 refraction S4 aspherical -226.9014 0.3387 refraction S5 Second lens (E2) aspherical -190.2984 8.2212 1.49 55.39 refraction S6 aspherical -52.9129 3.0734 refraction S7 Third lens (E3) aspherical 175.2235 11.3445 1.61 23.11 refraction S8 aspherical -74.4238 1.4766 refraction S9 (S9) spherical endless

[0135] Table 10

[0136] Face number <![CDATA[a0]]> <![CDATA[a1]]> <![CDATA[a2]]> <![CDATA[a3]]> S1 1.7318E-01 9.6863E-02 -4.4572E-02 5.2719E-03 S2 1.7318E-01 9.6863E-02 -4.4572E-02 5.2719E-03 S3 1.7318E-01 9.6863E-02 -4.4572E-02 5.2719E-03 S4 -2.5063E-01 8.8944E-02 1.2895E-02 -1.8220E-02 S5 2.3471E-01 7.6660E-02 -2.4657E-03 -6.3724E-02 S6 2.1155E-01 1.0203E-01 -8.2616E-02 9.2680E-03 S7 -1.0376E+00 -2.1803E-01 2.5416E-02 2.8979E-01 S8 1.2916E+00 -2.7952E-01 -1.2674E-03 6.6774E-02

[0137] Table 11

[0138] For example, when the optical system is applied to a VR device, the first side can be, for example, the eye side, and the second side can be, for example, the display side. Light from the display S9 sequentially passes through the third lens E3, the second lens E2, the first lens E1, and the quarter-wave plate QWP to reach the reflective polarizing element RP. It is reflected at the reflective polarizing element RP and passes again through the quarter-wave plate QWP and the first lens E1 to reach the second lens E2. Subsequently, the light beam is reflected again at the partial reflective layer BS on the second side surface S6 of the second lens E2 and sequentially passes through the second lens E2, the first lens E1, the quarter-wave plate QWP, and the reflective polarizing element RP, passes through the aperture STO, and finally exits towards the eye side. In an exemplary embodiment, the partial reflective layer can be a semi-transparent, semi-reflective film layer deposited on the second side surface S6 of the second lens E2. In this example, the partial reflective layer can be deposited in the region of the second side surface S6 of the second lens E2 that is away from the optical axis.

[0139] Table 12 provides the values ​​of parameters such as the maximum field of view (FOV), aperture number (Fno), effective focal length (f) of the optical system in Example 4, effective focal length (F1) of the first lens group (including the reflective polarizing element RP, the quarter-wave plate (QWP) and the first lens (E1), effective focal length (f2) of the second lens (E2) and effective focal length (f3) of the third lens (E3).

[0140]

[0141] Table 12

[0142] Figure 9A The on-axis chromatic aberration curve of the optical system of Embodiment 4 is shown, which represents the deviation of light of different wavelengths from the convergence focal point after passing through the lens. Figure 9B 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 9C The distortion curves of the optical system in Example 4 are shown, representing the distortion magnitudes corresponding to different half-field angles. According to... Figures 9A to 9C It can be seen that the optical system given in Example 4 can achieve good imaging quality.

[0143] Example 5

[0144] The following is for reference Figures 10 to 11C An optical system according to Embodiment 5 of this application is described. Figure 10 A schematic diagram of the structure of an optical system according to Embodiment 5 of this application is shown.

[0145] like Figure 10As shown, the optical system includes, in sequence from the first side to the second side along the optical axis: aperture STO, reflective polarizing element RP, quarter-wave plate QWP, first lens E1, second lens E2, third lens E3, and display S9.

[0146] like Figure 10 As shown, the reflective polarizing element RP has a first side surface S1 and a second side surface S2, the quarter-wave plate QWP has a first side surface S2 and a second side surface S3, and the first lens E1 has a first side surface S3 and a second side surface S4. Specifically, S2 is a shared surface between the second side surface of the reflective polarizing element RP and the first side surface of the quarter-wave plate QWP, and the second side surface of the reflective polarizing element RP is in contact with the first side surface of the quarter-wave plate QWP; S3 is a shared surface between the second side surface of the quarter-wave plate QWP and the first side surface of the first lens E1, and the second side surface of the quarter-wave plate QWP is in contact with the first side surface of the first lens E1. The second lens E2 has a first side surface S5 and a second side surface S6. The third lens E3 has a first side surface S7 and a second side surface S8. The optical system also includes a partially reflective layer BS (not shown) disposed on the second side surface S6 of the second lens E2.

[0147] Table 13 shows the basic parameters of the optical system of Embodiment 5, where the units for radius of curvature and thickness are millimeters (mm). Table 13 only lists the correspondence between surface numbers and some components on a partial basis. Due to the issue of shared surfaces between adjacent components, it is inconvenient to mark all components at the locations of shared surfaces in Table 13. Table 14 shows the higher-order coefficients that can be used for each aspherical mirror in Embodiment 5, where each aspherical surface shape can be defined by formula (1) given in Embodiment 1 above.

[0148]

[0149]

[0150] Table 13

[0151] Face number <![CDATA[a0]]> <![CDATA[a1]]> <![CDATA[a2]]> <![CDATA[a3 <!-- 15 -->]]> S1 -1.4345E-01 6.8938E-02 1.8020E-02 -1.0906E-06 S2 -1.4345E-01 6.8938E-02 1.8020E-02 -1.0906E-06 S3 -1.4345E-01 6.8938E-02 1.8020E-02 -1.0906E-06 S4 -3.2276E-01 2.8809E-02 -2.9282E-02 -4.3712E-02 S5 3.1209E-01 -4.7400E-02 -1.5831E-01 -6.6148E-03 S6 -2.0127E-02 4.1501E-02 -2.8304E-02 2.2660E-02 S7 -2.0946E-01 1.9303E-01 -3.2473E-02 4.8329E-02 S8 5.9797E-01 7.5649E-02 -3.0103E-01 1.0044E-01

[0152] Table 14

[0153] For example, when the optical system is applied to a VR device, the first side can be, for example, the eye side, and the second side can be, for example, the display side. Light from the display S9 sequentially passes through the third lens E3, the second lens E2, the first lens E1, and the quarter-wave plate QWP to reach the reflective polarizing element RP. It is reflected at the reflective polarizing element RP and passes again through the quarter-wave plate QWP and the first lens E1 to reach the second lens E2. Subsequently, the light beam is reflected again at the partial reflective layer BS on the second side surface S6 of the second lens E2 and sequentially passes through the second lens E2, the first lens E1, the quarter-wave plate QWP, and the reflective polarizing element RP, passes through the aperture STO, and finally exits towards the eye side. In an exemplary embodiment, the partial reflective layer can be a semi-transparent, semi-reflective film layer deposited on the second side surface S6 of the second lens E2. In this example, the partial reflective layer can be deposited in the region of the second side surface S6 of the second lens E2 that is away from the optical axis.

[0154] Table 15 provides the values ​​of parameters such as the maximum field of view (FOV), aperture number (Fno), effective focal length (f) of the optical system in Example 5, effective focal length (F1) of the first lens group (including the reflective polarizing element RP, the quarter-wave plate QWP, and the first lens E1), effective focal length (f2) of the second lens E2, and effective focal length (f3) of the third lens E3.

[0155]

[0156] Table 15

[0157] Figure 11A The on-axis chromatic aberration curve of the optical system of Embodiment 5 is shown, which represents the deviation of light of different wavelengths from the convergence focal point after passing through the lens. Figure 11B 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 11C The distortion curves of the optical system in Example 5 are shown, representing the distortion magnitudes corresponding to different half-field angles. According to... Figures 11A to 11C It can be seen that the optical system given in Example 5 can achieve good imaging quality.

[0158] Example 6

[0159] The following is for reference Figures 12 to 13C An optical system according to Embodiment 6 of this application is described. Figure 12 A schematic diagram of the structure of an optical system according to Embodiment 6 of this application is shown.

[0160] like Figure 12As shown, the optical system includes, in sequence from the first side to the second side along the optical axis: aperture STO, reflective polarizing element RP, quarter-wave plate QWP, first lens E1, second lens E2, third lens E3, and display S9.

[0161] like Figure 12 As shown, the reflective polarizing element RP has a first side surface S1 and a second side surface S2, the quarter-wave plate QWP has a first side surface S2 and a second side surface S3, and the first lens E1 has a first side surface S3 and a second side surface S4. Specifically, S2 is a shared surface between the second side surface of the reflective polarizing element RP and the first side surface of the quarter-wave plate QWP, and the second side surface of the reflective polarizing element RP is in contact with the first side surface of the quarter-wave plate QWP; S3 is a shared surface between the second side surface of the quarter-wave plate QWP and the first side surface of the first lens E1, and the second side surface of the quarter-wave plate QWP is in contact with the first side surface of the first lens E1. The second lens E2 has a first side surface S5 and a second side surface S6. The third lens E3 has a first side surface S7 and a second side surface S8. The optical system also includes a partially reflective layer BS (not shown) disposed on the second side surface S6 of the second lens E2.

[0162] Table 16 shows the basic parameters of the optical system of Embodiment 6, where the units for radius of curvature and thickness are millimeters (mm). Table 16 only lists the correspondence between surface numbers and some components on a partial basis. Due to the issue of shared surfaces between adjacent components, it is inconvenient to mark all components at the locations of shared surfaces in Table 16. Table 17 shows the higher-order coefficients that can be used for each aspherical mirror in Embodiment 6, where each aspherical surface shape can be defined by formula (1) given in Embodiment 1 above.

[0163]

[0164]

[0165] Table 16

[0166] Face number <![CDATA[a0]]> <![CDATA[a1]]> <![CDATA[a2]]> <![CDATA[a3]]> S1 -2.1712E-02 1.3117E-01 -1.0344E-02 -1.7705E-03 S2 -2.1712E-02 1.3117E-01 -1.0344E-02 -1.7705E-03 S3 -2.1712E-02 1.3117E-01 -1.0344E-02 -1.7705E-03 S4 -2.2357E-01 6.8785E-02 5.8637E-03 1.3164E-02 S5 2.9870E-01 5.5230E-02 5.5996E-03 4.1828E-03 S6 -1.7381E-01 1.5302E-01 -3.4292E-02 1.0244E-03 S7 -2.4055E-01 -1.6728E-01 -1.7089E-01 6.1945E-02 S8 -5.6240E-02 -1.0233E-01 -2.2354E-01 3.2467E-02

[0167] Table 17

[0168] For example, when the optical system is applied to a VR device, the first side can be, for example, the eye side, and the second side can be, for example, the display side. Light from the display S9 sequentially passes through the third lens E3, the second lens E2, the first lens E1, and the quarter-wave plate QWP to reach the reflective polarizing element RP. It is reflected at the reflective polarizing element RP and passes again through the quarter-wave plate QWP and the first lens E1 to reach the second lens E2. Subsequently, the light beam is reflected again at the partial reflective layer BS on the second side surface S6 of the second lens E2 and sequentially passes through the second lens E2, the first lens E1, the quarter-wave plate QWP, and the reflective polarizing element RP, passes through the aperture STO, and finally exits towards the eye side. In an exemplary embodiment, the partial reflective layer can be a semi-transparent, semi-reflective film layer deposited on the second side surface S6 of the second lens E2. In this example, the partial reflective layer can be deposited in the region of the second side surface S6 of the second lens E2 that is away from the optical axis.

[0169] Table 18 provides the values ​​of parameters such as the maximum field of view (FOV), aperture number (Fno), effective focal length (f) of the optical system in Example 6, effective focal length (F1) of the first lens group (including the reflective polarizing element RP, the quarter-wave plate QWP, and the first lens E1), effective focal length (f2) of the second lens E2, and effective focal length (f3) of the third lens E3.

[0170]

[0171] Table 18

[0172] Figure 13A The on-axis chromatic aberration curve of the optical system of Embodiment 6 is shown, which represents the deviation of light of different wavelengths from the convergence focal point after passing through the lens. Figure 13B 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 13C The distortion curves of the optical system in Example 6 are shown, representing the distortion magnitudes corresponding to different half-field angles. According to... Figures 13A to 13C It can be seen that the optical system given in Example 6 can achieve good imaging quality.

[0173] In summary, the relationships of the optical systems in Examples 1 to 6 are shown in Table 19.

[0174]

[0175]

[0176] Table 19

[0177] This application also provides an optical device, which can be a stand-alone projection device such as a projector, or a projection module integrated into a mobile electronic device such as a VR device. The optical device is equipped with the optical system described above.

[0178] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of protection involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the concept of this application. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. Optical system, characterized in that In order from the first side to the second side along the optical axis, the optical system comprises: a first lens group, a second lens, a third lens, and a display, wherein The first lens group comprises, in order from the first side to the second side, a reflective polarizing element, a quarter-wave plate, and a first lens, and a second side surface of the reflective polarizing element is attached to a first side surface of the quarter-wave plate, a second side surface of the quarter-wave plate is attached to a first side surface of the first lens; At least one of the first side surface of the first lens, the first side surface and the second side surface of the second lens is provided with a partial reflection layer; The first side surface of the first lens is a concave surface, and the second side surface of the first lens is a convex surface; The second side surface of the second lens is a convex surface; and The number of lenses with optical power in the optical system is three; The radius of curvature R1 of the first side surface of the first lens and the radius of curvature R4 of the second side surface of the second lens satisfy: 0.76≤R1 / R4≤1.89; The radius of curvature R1 of the first side surface of the first lens and the effective focal length f of the optical system satisfy: -4.22≤R1 / f≤-0.

75.

2. The optical system of claim 1, wherein, The central thickness CT1 of the first lens on the optical axis, and the distance TD from the first side surface of the first lens to the second side surface of the third lens on the optical axis satisfy: 0.09≤CT1 / TD≤0.

34.

3. The optical system of claim 1, wherein, The dispersion coefficient V1 of the first lens, the dispersion coefficient V2 of the second lens, the dispersion coefficient V3 of the third lens, the dispersion coefficient VRP of the reflective polarizing element, and the dispersion coefficient VQWP of the quarter-wave plate satisfy: 32.52≤(V1+V2+V3) / 3<VRP and 32.52≤(V1+V2+V3) / 3<VQWP.

4. The optical system of claim 1, wherein, The distance Tr1rBS from the first side surface of the first lens to the surface of the lens where the partial reflection layer is located on the optical axis, and the distance TD from the first side surface of the first lens to the second side surface of the third lens on the optical axis satisfy: 0.30<Tr1rBS / TD≤0.

63.

5. The optical system of claim 1, wherein, The radius of curvature R1 of the first side surface of the first lens, the central thickness CTRP of the reflective polarizing element on the optical axis, and the central thickness CTQWP of the quarter-wave plate on the optical axis satisfy: -304.28≤R1 / (CTRP+CTQWP)≤-48.

64.

6. The optical system of claim 1, wherein, The effective focal length f of the optical system, the sum ∑AT of the interval distance of the first lens group and the second lens on the optical axis and the interval distance of the second lens and the third lens on the optical axis satisfy: 8.23≤f / ∑AT≤136.

32.

7. The optical system of claim 1, wherein, The effective radius DT11 of the first side surface of the first lens, and the distance TD from the first side surface of the first lens to the second side surface of the third lens on the optical axis satisfy: 0.76≤DT11 / TD<1.

8.

8. The optical system of claim 1, wherein, A radius of curvature R1 of a first side surface of the first lens, a radius of curvature RBS of a lens surface on which the partial reflection layer is located, and an effective focal length f of the optical system satisfy: -6.45≤(R1+RBS) / f≤-1.

59.

9. The optical system according to any one of claims 1 to 8, wherein, A distance SAG11 on the optical axis from an intersection of the first side surface of the first lens on the optical axis to a maximum effective radius vertex of the first side surface of the first lens, a central thickness CT1 of the first lens on the optical axis, and an F number Fno of the optical system satisfy: -7.84≤SAG11 / CT1×Fno≤-4.

52.

10. The optical system according to any one of claims 1 to 8, wherein, A distance SAG22 on the optical axis from an intersection of the second side surface of the second lens on the optical axis to a maximum effective radius vertex of the second side surface of the second lens, and a radius of curvature R4 of the second side surface of the second lens satisfy: 0.08≤SAG22 / R4≤0.

43.

11. The optical system according to any one of claims 1 to 8, wherein, An effective focal length f of the optical system, a maximum field angle FOV of the optical system, a sum ∑CT of central thicknesses of the reflective polarizing element, the quarter-wave plate, the first lens, the second lens, and the third lens on the optical axis satisfy: 1.63≤f×tan(FOV / 2) / ∑CT≤3.

44.

12. The optical system of claim 1, wherein, The first lens group has positive refractive power, the second lens has positive refractive power, and the third lens has negative refractive power and its first side surface is concave.

13. The optical system of claim 12, wherein, An effective focal length F1 of the first lens group and an effective focal length f of the optical system satisfy: 0.8<F1 / f≤1.

01.

14. The optical system of claim 12, wherein, A central thickness CT1 of the first lens on the optical axis, a central thickness CT2 of the second lens on the optical axis, and a central thickness CT3 of the third lens on the optical axis satisfy: 5.60≤(CT1+CT2) / CT3≤10.

12.

15. The optical system of claim 1, wherein, The third lens has positive refractive power and its second side surface is convex.

16. The optical system of claim 15, wherein, A central thickness CT3 of the third lens on the optical axis, an effective focal length f of the optical system, and a maximum field angle FOV of the optical system satisfy: 0.27≤CT3 / (f×tan(FOV / 2))≤0.

45.

17. The optical system of claim 15, wherein, A radius of curvature R6 of the second side surface of the third lens and an effective focal length f3 of the third lens satisfy: -1.03≤R6 / f3≤-0.

19.

18. The optical system of claim 15, wherein, A dispersion coefficient V1 of the first lens, a dispersion coefficient V2 of the second lens, an effective focal length f of the optical system, and an effective focal length F1 of the first lens group satisfy: 2.58≤(V1-V2)×f / F1≤4.

83.

19. An optical device, characterized by An optical system as claimed in at least one of claims 1 to 18. An optical system as claimed in at least one of claims 1 to 18.

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