Optical system and optical device including the same

Abstract

The present application discloses an optical system and an optical device including the optical system. The optical system includes a lens barrel, a lens group and a spacer element group disposed in the lens barrel. The lens group includes a first lens, a reflective polarizing element, a first quarter wave plate and a second lens in sequence from the first side to the second side along the optical axis, wherein the first lens has positive optical power and the second lens has positive optical power; the optical element group consisting of the reflective polarizing element, the first quarter wave plate and the second lens has positive optical power. The spacer element group includes a first spacer element disposed between the first lens and the second lens and abutting against the second side surface of the first lens. The optical system satisfies: 0.05<|d1s‑d0s| / CT1<2.15, wherein d1s is the maximum inner diameter of the first side surface of the first spacer element in a direction perpendicular to the optical axis, d0s is the maximum inner diameter of the first side end surface of the lens barrel in a direction perpendicular to the optical axis, and CT1 is the center thickness of the first lens on the optical axis.

Description

Technical Field

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

[0002] In recent years, Virtual Reality (VR) technology has received widespread attention and application. It provides users with an immersive experience, making users feel as if they are in a virtual world in a three-dimensional space. In order to provide a more immersive visual experience, in existing virtual reality systems, such as glasses and helmets, head-mounted displays (HMD), precision optical components are usually required to ensure image clarity and width of field of view. As key components of VR devices such as head-mounted displays (HMD), the design of the lens barrel and lens group is crucial to reducing aberrations, improving image quality and comfort.

[0003] Common lens group designs usually require a combination of multiple lenses to correct various aberrations and optimize system performance. However, the lens group design of existing VR devices still has some shortcomings. First, the lens groups of existing VR devices usually use a large number of lenses or thick lenses, which will increase the volume and weight of the system, thereby affecting the user's wearing comfort. Secondly, the spacing and arrangement between the lens groups have an important impact on the overall performance of the system. Existing designs often find it difficult to achieve a compact structure and lightweight design while ensuring image quality.

[0004] Therefore, it is one of the important research topics for technicians in this field to reasonably design the arrangement of lenses, reflective elements and spacer elements to obtain a catadioptric optical system with good imaging quality and compact structure. Summary of the invention

[0005] A first aspect of the present application provides an optical system, which includes a lens barrel, a lens group and a spacer element group disposed in the lens barrel. The lens group sequentially includes a first lens, a reflective polarizing element, a first quarter-wave plate and a second lens along the optical axis from the first side to the second side. Among them, the first lens has a positive optical power, and the second lens has a positive optical power; the optical element group composed of the reflective polarizing element, the first quarter-wave plate and the second lens has a positive optical power. The spacer element group includes a first spacer element disposed between the first lens and the second lens and abutted against the second side surface of the first lens. The optical system satisfies: 0.05 < |d1s - d0s| / CT1 < 2.15, where d1s is the maximum inner diameter of the first side surface of the first spacer element in the direction perpendicular to the optical axis, d0s is the maximum inner diameter of the first side end surface of the lens barrel in the direction perpendicular to the optical axis, and CT1 is the central thickness of the first lens on the optical axis.

[0006] In one embodiment, the optical system satisfies: 0.65 < f / L < 1.05, where f is the effective focal length of the optical system, and L is the maximum distance along the optical axis from the first side end surface of the lens barrel to the second side end surface.

[0007] In one embodiment, the optical system further includes a second spacer element abutted against the second side surface of the second lens. The optical system satisfies: 0.35 < EP12 / CT2 ≤ 0.50, where EP12 is the distance along the optical axis between the second side surface of the first spacer element and the first side surface of the second spacer element, and CT2 is the central thickness of the second lens on the optical axis.

[0008] In one embodiment, the optical system satisfies: 0.70 < d0s / 2 / DT11 < 0.90, where d0s is the maximum inner diameter of the first side end surface of the lens barrel in the direction perpendicular to the optical axis, and DT11 is the maximum effective radius of the first side surface of the first lens.

[0009] In one embodiment, the optical system satisfies: 0.30 < |SAG11| / |SAG22| ≤ 0.90, where SAG11 is the axial distance between the intersection of the first side surface of the first lens and the optical axis and the vertex of the effective radius of the first side surface of the first lens, and SAG22 is the axial distance between the intersection of the second side surface of the second lens and the optical axis and the vertex of the effective radius of the second side surface of the second lens.

[0010] In one embodiment, the optical system further includes a second spacer element abutted against the second side surface of the second lens. The optical system satisfies: 1.10 ≤ CP2 / CT2 < 1.50, where CP2 is the maximum thickness of the second spacer element along the optical axis, and CT2 is the central thickness of the second lens on the optical axis.

[0011] In one embodiment, the optical system satisfies: 1.25 < f1 / R1 ≤ 1.50, where f1 is the effective focal length of the first lens and R1 is the radius of curvature of the first side surface of the first lens.

[0012] In one embodiment, the optical system further includes a second spacer element abutting against the second side surface of the second lens, and the optical system satisfies: 1.05 < D2s / DT21 < 2.65, where D2s is the maximum outer diameter of the first side surface of the second spacer element in a direction perpendicular to the optical axis, and DT21 is the maximum effective radius of the first side surface of the second lens.

[0013] In one embodiment, the optical system further includes a second spacer element abutting against the second side surface of the second lens, and the optical system satisfies: 1.05 < D0m / D2m ≤ 1.15, where D0m is the maximum outer diameter of the second side surface of the lens barrel in a direction perpendicular to the optical axis, and D2m is the maximum outer diameter of the second side surface of the second spacer element in a direction perpendicular to the optical axis.

[0014] In one embodiment, the optical system satisfies: 1.50 < L / (CT1 + CT2) < 2.30, where L is the maximum distance along the optical axis from the first side end face of the lens barrel to the second side end face, CT1 is the central thickness of the first lens on the optical axis, and CT2 is the central thickness of the second lens on the optical axis.

[0015] In one embodiment, the optical system satisfies: -5.00 < R4 / F2 < -4.40, where R4 is the radius of curvature of the second side surface of the second lens and F2 is the optical power of the optical element group.

[0016] In one embodiment, the optical system further includes a second spacer element abutting against the second side surface of the second lens, and the optical system satisfies: 2.80 < d1s / f1 + d2s / F2 < 3.10, where d1s is the maximum inner diameter of the first side surface of the first spacer element in a direction perpendicular to the optical axis, f1 is the effective focal length of the first lens, d2s is the maximum inner diameter of the first side surface of the second spacer element in a direction perpendicular to the optical axis, and F2 is the optical power of the optical element group.

[0017] In one embodiment, the optical system further includes a second spacer element abutting against the second side surface of the second lens, and the optical system satisfies: 0.15 < |d2s - d2m| / CT2 < 1.55, where d2s is the maximum inner diameter of the first side surface of the second spacer element in a direction perpendicular to the optical axis, d2m is the maximum inner diameter of the second side surface of the second spacer element in a direction perpendicular to the optical axis, and CT2 is the central thickness of the second lens on the optical axis.

[0018] In one embodiment, the optical system satisfies: 1.25 ≤ CT2 / CT1 < 1.80, where CT2 is the central thickness of the second lens on the optical axis, and CT1 is the central thickness of the first lens on the optical axis.

[0019] In one embodiment, the optical system satisfies: -6.20 < R4 / f < -5.60, where R4 is the radius of curvature of the second surface of the second lens, and f is the effective focal length of the optical system.

[0020] A second aspect of the present application provides an optical system, which includes a lens barrel, a lens group and a spacer element group disposed in the lens barrel. The lens group sequentially includes a first lens, a reflective polarizing element, a first quarter-wave plate and a second lens along the optical axis from the first side to the second side. The first lens has a positive optical power, and the second lens has a positive optical power; the optical element group composed of the reflective polarizing element, the first quarter-wave plate and the second lens has a positive optical power. The spacer element group includes a first spacer element and a second spacer element. The first spacer element is disposed between the first lens and the second lens and abuts against the first side surface of the second side surface of the first lens. The second spacer element abuts against the second side surface of the second lens. The optical system satisfies: 2.80 < d1s / f1 + d2s / F2 < 3.10, where d1s is the maximum inner diameter of the first side surface of the first spacer element in the direction perpendicular to the optical axis, f1 is the effective focal length of the first lens, d2s is the maximum inner diameter of the first side surface of the second spacer element in the direction perpendicular to the optical axis, and F2 is the optical power of the optical element group.

[0021] A third aspect of the present application further provides an optical device, which includes the optical system provided by at least one of the above embodiments.

[0022] The optical system provided by the present application is a catadioptric optical system. By reasonably arranging the structures of two lenses, a reflective polarizing element, a first quarter-wave plate, a partial reflection layer, spacer elements and a lens barrel, the first lens has a positive optical power, and the optical element group composed of the reflective polarizing element, the first quarter-wave plate and the second lens has a positive optical power. This means that the optical element group can converge light, so that the light emitted from the display screen can be more accurately focused on the user's retina after passing through the optical element group, thereby improving the clarity of the image. The optical system provided by the present application also satisfies 0.05 < |d1s - d0s| / CT1 < 2.15. By controlling the inner diameter sizes of the first spacer element and the lens barrel and the central thickness of the first lens, it is beneficial to make the structure of the entire lens group more compact. This design helps to reduce the volume and weight of the virtual reality system and improve the wearing comfort of the user. The optical system provided by the present application has characteristics such as good projection quality and a small total length. Description of the Drawings

[0023] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings. In the drawings:

[0024] Figure 1 A schematic diagram showing a structural arrangement diagram of an optical system according to the present application and some parameters;

[0025] Figure 2 A schematic structural diagram of an optical system according to Embodiment 1 of the present application is shown;

[0026] Figure 3 A schematic structural diagram of an optical system according to Embodiment 2 of the present application is shown;

[0027] Figure 4 A schematic structural diagram of an optical system according to Embodiment 3 of the present application is shown;

[0028] Figure 5 A schematic structural diagram of an optical system according to Embodiment 4 of the present application is shown;

[0029] Figure 6 A schematic structural diagram of an optical system according to Embodiment 5 of the present application is shown;

[0030] Figure 7 A schematic structural diagram of an optical system according to Embodiment 6 of the present application is shown;

[0031] Figure 8 A schematic structural diagram of an optical system according to Embodiment 7 of the present application is shown;

[0032] Fig. 9 A schematic structural diagram of an optical system according to Embodiment 8 of the present application is shown;

[0033] Fig.10 A schematic structural diagram of an optical system according to Example 9 of the present application is shown. DETAILED DESCRIPTION

[0034] In order to better understand the present application, a more detailed description will be made of various aspects of the present application with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application, and are not intended to limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0035] It should be noted that in this specification, the expressions of first, second, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teaching of the present 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.

[0036] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0037] In this article, the paraxial area refers to the area near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial area; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial area. The judgment of the surface type in the paraxial area can be judged according to the general method in this field, for example, judging the concave and convex by the positive and negative R value (R refers to the radius of curvature of the paraxial area). In this article, the surface of each lens closest to the subject is called the object side of the lens, and the surface of each lens closest to the imaging side is called the image side of the lens. For the object side, when the R value is positive, it is judged as a convex surface, and when the R value is negative, it is judged as a concave surface; for the image side, when the R value is positive, it is judged as a concave surface, and when the R value is negative, it is judged as a convex surface.

[0038] It should be understood that the optical lens provided in the present application can be used for both video recording and projection. When the optical lens provided in the present application is used for a video recording lens, the "first side" referred to in this article may refer to the object side, and the "second side" may refer to the image side. The light from the object side may be imaged on the image side, for example, wherein the video recording lens may be, for example, a vehicle-mounted camera, an infrared camera, a drone camera, a night vision camera, a security monitoring camera, etc.; when the optical lens provided in the present application is used for a projection lens, the "first side" referred to in this article may refer to the object side, and the "second side" may refer to the light source side. The light from the light source side is projected to the first side after passing through the optical lens, for example, an image may be formed on the first side or an illuminated area may be illuminated.

[0039] It should also be understood that the terms "comprises", "including", "having", "includes" and / or "comprising", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire listed features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0040] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] The optical system according to the exemplary embodiment of the present application includes a lens barrel, a lens group and a spacer element group disposed in the lens barrel, and the lens group may include: a first lens, a reflective polarizing element, a first quarter wave plate, and a second lens in sequence from the first side to the second side along the optical axis. Exemplarily, the second side surface of the reflective polarizing element is bonded to the first side surface of the first quarter wave plate, and the second side surface of the first quarter wave plate is bonded to the first side surface of the second lens.

[0043] Those skilled in the art should understand that the reflective polarizing element can reflect polarized light in a certain direction and can also transmit polarized light orthogonal to the polarization direction, and the quarter wave plate can change the state of polarized light. The combination of light reflection and refraction using the reflective polarizing element and the quarter wave plate can fold the required optical path, which can effectively shorten the length of the optical system.

[0044] According to the optical system of the exemplary embodiment of the present application, it may also include a spacer element group. For example, the spacer element group may include a first spacer element disposed between the first lens and the second lens and against the second side of the first lens. For example, the spacer element group may include a second spacer element against the second side of the second lens. It should be understood that the present application does not specifically limit the number of spacer elements, and the entire optical system may include any number of spacer elements. The spacer element helps the optical system intercept excess refractive and reflective light paths and reduce the generation of stray light and ghosting. Auxiliary support can be added between the spacer element and the lens barrel, which is conducive to improving the poor assembly stability between the lenses and the low performance yield. By reasonably setting the number, thickness, inner diameter and outer diameter of the spacer elements, it is conducive to improving the assembly stability of the optical system and blocking stray light, thereby improving the projection quality of the optical system.

[0045] Figure 1 The structure arrangement diagram of an optical system according to the present application and a schematic diagram of some parameters are shown. Those skilled in the art should understand that some parameters of lenses commonly used in the art, such as the center thickness CT1 of the first lens on the optical axis, are not shown in FIG. Figure 1 Shown in. Figure 1 Only some parameters of the lens barrel and the spacer element of an optical system of the present application are shown as examples to facilitate a better understanding of the present invention. Figure 1 As shown, d1s is the maximum inner diameter of the first side surface of the first spacing element in the direction perpendicular to the optical axis, d0s is the maximum inner diameter of the first side end surface of the lens barrel in the direction perpendicular to the optical axis, L is the maximum distance from the first side end surface to the second side end surface of the lens barrel along the optical axis, EP12 is the distance between the second side surface of the first spacing element and the first side surface of the second spacing element in the direction of the optical axis, CP2 is the maximum thickness of the second spacing element in the direction of the optical axis, DT11 is the maximum effective radius of the first side surface of the first lens, DT21 is the maximum effective radius of the first side surface of the second lens, d2s is the maximum effective radius of the first side surface of the second spacing element in the direction perpendicular to the optical axis , d2m is the maximum inner diameter of the second side of the second spacing element in the direction perpendicular to the optical axis, D2s is the maximum outer diameter of the first side of the second spacing element in the direction perpendicular to the optical axis, D0m is the maximum outer diameter of the second side of the lens barrel in the direction perpendicular to the optical axis, D2m is the maximum outer diameter of the second side of the second spacing element in the direction perpendicular to the optical axis, SAG11 is the axial distance between the intersection of the first side of the first lens and the optical axis to the effective radius vertex of the first side of the first lens, and SAG22 is the axial distance between the intersection of the second side of the second lens and the optical axis to the effective radius vertex of the second side of the second lens.

[0046] In an exemplary embodiment, the optical system can be applied to, for example, a VR device, and the optical system also includes an image surface (or display screen) disposed on the second side of the second lens. The first side can be, for example, a human eye side, and the second side can be, for example, an image surface side. The image light on the image surface screen can be finally projected to the user's eyes after multiple refractions and reflections, for example, through the second lens, the reflective polarizing element, the first quarter-wave plate, and the first lens.

[0047] In an exemplary embodiment, the optical system further includes a partial reflective layer disposed on the second side surface of the second lens. The partial reflective layer has a semi-transmissive and semi-reflective function.

[0048] In an exemplary embodiment, the optical system further includes other elements disposed between the second lens and the image plane, such as an antireflection film, a second quarter wave plate, a linear polarizer, a protective glass, etc.

[0049] In some embodiments, Figures 2 to 10 As shown, the optical system may include a lens barrel P0 and a lens group and a spacer element group disposed in the lens barrel P0. The lens group includes an aperture STO (not shown), a first lens E1, a reflective polarizing element RP, a first quarter wave plate QWP1, a second lens E2, a partial reflection layer BS, an anti-reflection film AR, a second quarter wave plate QWP2, a linear polarizing plate LP, a protective glass GL and an image surface (not shown) in order from the side close to the human eye to the side close to the screen along the optical axis. Among them, the anti-reflection film AR, the second quarter wave plate QWP2, the linear polarizing plate LP and the protective glass GL are attached together in order from the side close to the human eye to the side close to the screen. The light emitted from the image surface screen passes through the protective glass GL, the linear polarizer LP, the second quarter-wave plate QWP2, the anti-reflection film AR, the second lens E2, the first quarter-wave plate QWP1 to reach the reflective polarizer RP, is reflected at the reflective polarizer RP and passes through the first quarter-wave plate QWP1 and the second lens E2 again to reach the second side surface of the second lens E2, and then the light beam is reflected again at the partial reflection layer BS on the second side surface of the second lens E2 and passes through the second lens E2, the first quarter-wave plate QWP1, the reflective polarizer RP, the first lens E1 in sequence, passes through the aperture STO and is finally emitted toward the human eye side.

[0050] In an exemplary embodiment, the reflective polarizing element and the first quarter-wave plate are compounded, and the desired structure can be obtained through a single attaching process operation, rather than two attaching operations, thereby reducing the angular position error caused by attaching and improving the imaging quality.

[0051] In an exemplary embodiment, the optical system of the present application may satisfy: 0.05<|d1s-d0s| / CT1<2.15, wherein d1s is the maximum inner diameter of the first side surface of the first spacing element in a direction perpendicular to the optical axis, d0s is the maximum inner diameter of the first side end surface of the lens barrel in a direction perpendicular to the optical axis, and CT1 is the center thickness of the first lens on the optical axis. Satisfying 0.05<|d1s-d0s| / CT1<2.15, by controlling the inner diameter size of the first spacing element, the lens barrel, and the center thickness of the first lens, it is helpful to make the structure of the entire lens group more compact. When the optical system is applied to, for example, VR equipment, this design helps to reduce the volume and weight of the virtual reality system and improve the wearing comfort of the user.

[0052] On one hand, the present application provides an optical system, which includes a lens barrel, a lens group and a spacer element group disposed in the lens barrel, wherein the lens group includes a first lens, a reflective polarizing element, a first quarter wave plate and a second lens in sequence from the first side to the second side along the optical axis, wherein the first lens has positive optical power, and the second lens has positive optical power; the optical element group consisting of the reflective polarizing element, the first quarter wave plate and the second lens has positive optical power. The spacer element group includes a first spacer element disposed between the first lens and the second lens and against the second side surface of the first lens. The optical system also satisfies: 0.05<|d1s-d0s| / CT1<2.15, wherein d1s is the maximum inner diameter of the first side surface of the first spacer element in a direction perpendicular to the optical axis, d0s is the maximum inner diameter of the first side end surface of the lens barrel in a direction perpendicular to the optical axis, and CT1 is the center thickness of the first lens on the optical axis. The present application reasonably arranges the structure of two lenses, a reflective polarizing element, a first quarter wave plate, a partial reflective layer, a spacer element, and a lens barrel, wherein the first lens has a positive focal length, and the optical element group consisting of the reflective polarizing element, the first quarter wave plate, and the second lens has a positive focal length, which means that the optical element group can converge light, so that the light emitted from the display screen can be more accurately focused on the user's retina after passing through the optical element group, thereby improving the clarity of the image. The present application also controls the inner diameter size of the first spacer element, the lens barrel, and the center thickness of the first lens to meet 0.05<|d1s-d0s| / CT1<2.15, which is conducive to making the structure of the entire lens group more compact. This design helps to reduce the volume and weight of the virtual reality system, improve the wearing comfort of the user, and enable the optical system provided by the present application to have the characteristics of good projection quality and a small total length.

[0053] In an exemplary embodiment, the optical system of the present application may satisfy: 0.65 < f / L < 1.05, where f is the effective focal length of the optical system and L is the maximum distance along the optical axis from the first side end face of the lens barrel to the second side end face. By satisfying 0.65 < f / L < 1.05, by controlling the ratio of the effective focal length f of the optical system to the lens barrel length L, key imaging quality indicators such as the resolution, distortion, and chromatic aberration of the optical system can be optimized. A suitable f / L ratio helps to reduce aberrations and improve the clarity and accuracy of the image. At the same time, on the premise of ensuring the imaging quality, by adjusting the ratio of the focal length f to the lens barrel length L, a more compact optical system can be designed, which is particularly important for optical devices that require miniaturization and lightweight (such as mobile phone cameras, endoscopes, etc.). The ratio of the focal length f to the lens barrel length L also affects the light collection efficiency of the optical system. A suitable f / L ratio helps to maximize the clear aperture of the system and improve the utilization rate of light, so as to obtain better imaging effects in low-light environments. By optimizing the ratio relationship between the focal length f and the lens barrel length L, the complexity and manufacturing cost of the system can be reduced while ensuring the imaging quality, which has important economic significance for enterprises that mass-produce optical devices.

[0054] In an exemplary embodiment, the optical system of the present application may satisfy: 0.35 < EP12 / CT2 ≤ 0.50, where EP12 is the distance along the optical axis between the second side face of the first spacer element and the first side face of the second spacer element, and CT2 is the central thickness of the second lens on the optical axis. By satisfying 0.35 < EP12 / CT2 ≤ 0.50, by controlling the ratio of the spacing distance EP12 between the first spacer element and the second spacer element to the thickness CT2 of the second lens, the optical system can be made more compact. A smaller EP12 / CT2 ratio helps to reduce the overall length of the optical system and make it more suitable for miniaturized and lightweight application scenarios. A suitable ratio relationship between EP12 and CT2 helps to reduce aberrations such as spherical aberration and coma, and obtain a clearer image, thereby improving the imaging quality. An appropriate ratio of EP12 to CT2 helps to enhance the mechanical stability of the system. This is particularly important for optical devices that need to withstand external disturbances such as vibration and shock. The ratio of EP12 to CT2 also affects the light transmission efficiency. A suitable ratio of EP12 to CT2 helps to reduce the loss of light in the system and improve the utilization rate of light.

[0055] In an exemplary embodiment, the optical system of the present application may satisfy: 0.70 < d0s / 2 / DT11 < 0.90, where d0s is the maximum inner diameter of the first side end face of the lens barrel in the direction perpendicular to the optical axis, and DT11 is the maximum effective radius of the first side face of the first lens. Satisfying 0.70 < d0s / 2 / DT11 < 0.90 helps to ensure that sufficient light can enter the optical system and reduce the loss of light at the entrance of the lens barrel, which is crucial for improving the light transmission efficiency and imaging brightness of the system. By controlling the ratio of the inner diameter d0s of the first side end face of the lens barrel to the maximum effective radius DT11 of the first side face of the first lens, a more compact optical system can be designed. A smaller d0s / 2 / DT11 ratio helps to reduce the volume and weight of the entire system, making it more suitable for miniaturized and lightweight application scenarios. An appropriate d0s / 2 / DT11 ratio relationship helps to reduce aberrations such as vignetting, thereby improving the imaging quality.

[0056] In an exemplary embodiment, the optical system of the present application may satisfy: 0.30 < |SAG11| / |SAG22| ≤ 0.90, where SAG11 is the axial distance between the intersection point of the first side face of the first lens and the optical axis and the vertex of the effective radius of the first side face of the first lens, and SAG22 is the axial distance between the intersection point of the second side face of the second lens and the optical axis and the vertex of the effective radius of the second side face of the second lens. Satisfying 0.30 < |SAG11| / |SAG22| ≤ 0.90, the ratio relationship between SAG11 and SAG22 has various effects on the efficacy of the optical system. A suitable SAG11 and SAG22 ratio helps to reduce the length of the entire system, making it more suitable for miniaturized and lightweight application scenarios. An appropriate SAG11 and SAG22 ratio helps to reduce aberrations such as spherical aberration and coma, thereby improving the imaging quality. The SAG11 and SAG22 ratio also affects the light transmission efficiency. A suitable SAG11 and SAG22 ratio helps to reduce the reflection and scattering of light on the lens surface and improve the utilization rate of light. An appropriate SAG11 and SAG22 ratio also provides more flexibility for the design and adjustment of the system. Designers can optimize the performance of the system by adjusting these parameters according to specific application requirements, which has important economic significance for enterprises that mass-produce optical devices.

[0057] In an exemplary embodiment, the optical system of the present application may satisfy: 1.10 ≤ CP2 / CT2 < 1.50, where CP2 is the maximum thickness of the second spacer element along the optical axis direction, and CT2 is the central thickness of the second lens on the optical axis. Satisfying 1.10 ≤ CP2 / CT2 < 1.50, by controlling the ratio of the thickness of the second spacer element to the central thickness of the second lens, a more compact optical system can be designed while ensuring the imaging quality. An appropriate ratio of CP2 to CT2 helps to reduce the length and volume of the entire system, making it more suitable for miniaturized and lightweight application scenarios. The ratio relationship between CP2 and CT2 affects the aberration correction of the system. By optimizing the ratio of CP2 to CT2, aberrations such as spherical aberration and coma of the system can be balanced, thereby obtaining a clearer image and higher imaging quality. The thickness of the spacer element also affects the light transmission efficiency. An appropriate thickness of the spacer element can reduce the reflection and scattering of light on the surface of the spacer element, thereby improving the utilization rate of light and the light transmission efficiency of the system.

[0058] In an exemplary embodiment, the optical system of the present application may satisfy: 1.25 < f1 / R1 ≤ 1.50, where f1 is the effective focal length of the first lens, and R1 is the radius of curvature of the first surface of the first lens. Satisfying 1.25 < f1 / R1 ≤ 1.50, by controlling the ratio of the effective focal length of the first lens to the radius of curvature of its first surface, the aberration correction of the system, such as spherical aberration and coma, can be optimized. A suitable ratio of f1 to R1 helps to obtain a clearer image and improve the imaging quality. The ratio of the effective focal length of the first lens to the radius of curvature of its first surface also affects the focal length adjustment range of the system. By optimizing the ratio of f1 to R1, a larger zoom ability or a wider focal length range can be provided while maintaining the compactness of the system. The radius of curvature and focal length of the lens also affect the light transmission efficiency. A suitable ratio of f1 to R1 helps to reduce the reflection and scattering of light on the lens surface, improve the utilization rate of light, and thus obtain better imaging effects in low-light environments.

[0059] In an exemplary embodiment, the optical system of the present application may satisfy: 1.05 < D2s / DT21 < 2.65, where D2s is the maximum outer diameter of the first side surface of the second spacer element in a direction perpendicular to the optical axis, and DT21 is the maximum effective radius of the first side surface of the second lens. Satisfying 1.05 < D2s / DT21 < 2.65 allows for the design of a more compact optical system while ensuring imaging quality. An appropriate ratio of D2s to DT21 helps reduce the volume and weight of the entire system, making it more suitable for miniaturized and lightweight application scenarios. The ratio between the outer diameter of the first side surface of the second spacer element and the effective radius of the first side surface of the second lens affects the incident and exit angles of light. A suitable ratio helps reduce light blockage at the edges of the spacer element and the lens, thereby improving light utilization and imaging quality. The effective radius of the lens and the outer diameter of the spacer element also affect the aberration correction of the system. By optimizing this ratio, aberrations such as spherical aberration and coma of the system can be balanced, resulting in a clearer image.

[0060] In an exemplary embodiment, the optical system of the present application may satisfy: 1.05 < D0m / D2m ≤ 1.15, where D0m is the maximum outer diameter of the second side surface of the lens barrel in a direction perpendicular to the optical axis, and D2m is the maximum outer diameter of the second side surface of the second spacer element in a direction perpendicular to the optical axis. The ratio between D0m and D2m has various effects on the design and performance of the optical system. Briefly, its effects are mainly reflected in the following aspects. 1) By controlling the ratio of the outer diameter of the second side surface of the lens barrel to the outer diameter of the second side surface of the second spacer element, the compactness of the optical system can be further optimized, which helps reduce the volume of the entire system and makes it more suitable for application scenarios with limited space. 2) The ratio between the outer diameter of the second side surface of the lens barrel and the outer diameter of the second side surface of the second spacer element affects the light transmission and blockage conditions. A suitable ratio helps reduce light blockage at the edges of the lens barrel and the spacer element, thereby improving light utilization and imaging quality. 3) By optimizing the ratio of the outer diameter of the second side surface of the lens barrel to the outer diameter of the second side surface of the second spacer element, a better heat dissipation structure can be designed to improve the thermal stability and reliability of the system. 4) The ratio between the outer diameter of the second side surface of the lens barrel and the outer diameter of the second side surface of the second spacer element provides more flexibility for the design and adjustment of the system. By adjusting these parameters, the performance of the system, such as focal length, field of view, and depth of field, can be optimized while maintaining the compactness and stability of the system. 5) By optimizing the ratio of the outer diameter of the second side surface of the lens barrel to the outer diameter of the second side surface of the second spacer element, the complexity and manufacturing cost of the system can be reduced while ensuring imaging quality and system stability.

[0061] In an exemplary embodiment, the optical system of the present application may satisfy: 1.50 < L / (CT1 + CT2) < 2.30, where L is the maximum distance from the first side end face to the second side end face of the lens barrel along the optical axis direction, CT1 is the central thickness of the first lens on the optical axis, and CT2 is the central thickness of the second lens on the optical axis. By satisfying 1.50 < L / (CT1 + CT2) < 2.30, a more compact optical system can be designed by controlling the ratio of the sum of the central thicknesses of the first lens and the second lens to the system length. A larger ratio (i.e., L is larger relative to CT1 + CT2) means that the system may have a longer optical path, but the lens itself is thinner, which helps to reduce the volume and weight of the entire system. Appropriate lens thickness helps to enhance the mechanical stability of the system. Thicker lenses may be more resistant to vibration and shock, thus ensuring the long-term stable operation of the system. By optimizing the ratio relationship between L and CT1 + CT2, while ensuring the imaging quality and system stability, the processing difficulty of the lens and the overall manufacturing cost of the system can be reduced. During the design process, it is necessary to balance the thickness of the lens and the overall performance of the system. Thinner lenses may help to reduce the volume and weight of the system, but may also lead to an increase in aberration or a decrease in light transmission efficiency. Therefore, by optimizing this ratio relationship, while maintaining the compactness of the system, it can be ensured that the lens has sufficient thickness to provide good optical performance.

[0062] In an exemplary embodiment, the optical system of the present application may satisfy: -5.00 < R4 / F2 < -4.40, where R4 is the radius of curvature of the second side face of the second lens, and F2 is the optical power of the optical element group. The optical power is the reciprocal of the focal length and represents the ability of the system to converge or diverge light. The ratio relationship between the radius of curvature and the optical power directly affects the aberration correction of the system, including spherical aberration, coma aberration, etc. By satisfying -5.00 < R4 / F2 < -4.40, by optimizing the ratio relationship between the radius of curvature R4 of the second side face of the second lens and the optical power F2 of the optical element group, better imaging quality can be obtained while maintaining the compactness of the system. The ratio of the radius of curvature of the second side face of the second lens to the optical power of the optical element group also affects the focal length adjustment range of the system. By adjusting this ratio, a larger zooming ability or a wider focal length range can be provided while maintaining the compactness of the system. The radius of curvature of the second side face of the second lens affects the light transmission path and focusing effect. A suitable ratio of R4 to F2 helps to reduce the reflection and scattering of light on the lens surface, improving the light utilization rate and imaging quality.

[0063] In an exemplary embodiment, the optical system of the present application may satisfy: 2.80 < d1s / f1 + d2s / F2 < 3.10, where d1s is the maximum inner diameter of the first side surface of the first spacer element in the direction perpendicular to the optical axis, f1 is the effective focal length of the first lens, d2s is the maximum inner diameter of the first side surface of the second spacer element in the direction perpendicular to the optical axis, and F2 is the optical power of the optical element group. Satisfying 2.80 < d1s / f1 + d2s / F2 < 3.10, by controlling the ratio of the inner diameter of the first spacer element to the optical power of the first lens and the ratio of the inner diameter of the second spacer element to the optical power of the second lens, a more compact optical system can be designed while maintaining the system performance. A larger ratio (i.e., d1s is larger relative to |f1|, and d2s is larger relative to |F2|) may mean a longer optical path or a larger spacer element, but compactness may also be achieved by optimizing the layout. The inner diameter of the spacer element and the optical power of the lens jointly affect the aberration correction of the system. By optimizing this ratio relationship, better imaging quality can be obtained while maintaining the system compactness. The inner diameter of the spacer element affects the light transmission path and the occlusion situation. A suitable ratio helps to reduce the occlusion of light at the edge of the spacer element, improving the light utilization rate and imaging quality. An appropriate ratio of the inner diameter of the spacer element to the optical power of the lens helps to enhance the mechanical stability of the system, which is particularly important for optical devices that need to withstand external disturbances such as vibration and shock. The inner diameter of the spacer element and the optical power of the lens also affect the manufacturing cost. By optimizing this ratio relationship, the complexity and manufacturing cost of the system can be reduced while ensuring the imaging quality and system stability. It should be noted that this ratio relationship is not isolated and needs to be coordinated with other optical parameters (such as the effective focal length of the lens, the total length of the system, the aberration correction requirements, etc.) to achieve the best overall performance. In addition, f1 represents the effective focal length of the first lens, F2 represents the optical power of the optical element group composed of the reflective polarizing element, the first quarter-wave plate, and the second lens. The optical power is the reciprocal of the focal length and has a positive or negative sign. In actual design, it is necessary to ensure that the positive or negative signs of parameters such as f1 and F2 match the actual ability of the lens to converge or diverge light.

[0064] On the other hand, the present application also provides an optical system, which includes a lens barrel and a lens group and a spacer element group disposed in the lens barrel. The lens group sequentially includes a first lens, a reflective polarizing element, a first quarter-wave plate, and a second lens along the optical axis from the first side to the second side. Among them, the first lens has a positive optical power, and the second lens has a positive optical power; the optical element group composed of the reflective polarizing element, the first quarter-wave plate, and the second lens has a positive optical power. The spacer element group includes a first spacer element and a second spacer element. The first spacer element is disposed between the first lens and the second lens and abuts against the second side surface of the first lens, and the second spacer element abuts against the second side surface of the second lens. The optical system satisfies: 2.80 < d1s / f1 + d2s / F2 < 3.10, where d1s is the maximum inner diameter of the first side surface of the first spacer element in the direction perpendicular to the optical axis, f1 is the effective focal length of the first lens, d2s is the maximum inner diameter of the first side surface of the second spacer element in the direction perpendicular to the optical axis, and F2 is the optical power of the optical element group. By reasonably arranging the structures of the two lenses, the reflective polarizing element, the first quarter-wave plate, the partial reflection layer, the spacer elements, and the lens barrel, the first lens has a positive optical power, and the optical element group composed of the reflective polarizing element, the first quarter-wave plate, and the second lens has a positive optical power, which means that the optical element group can converge light, so that the light emitted from the display screen can be more accurately focused on the user's retina after passing through the optical element group, thereby improving the clarity of the image. At the same time, by controlling the ratio of the inner diameter of the first spacer element to the optical power of the first lens and the ratio of the inner diameter of the second spacer element to the optical power of the second lens, a more compact optical system can be designed while maintaining the system performance.

[0065] In an exemplary embodiment, the optical system of the present application may satisfy: 0.15<|d2s-d2m| / CT2<1.55, wherein d2s is the maximum inner diameter of the first side surface of the second spacer element in a direction perpendicular to the optical axis, d2m is the maximum inner diameter of the second side surface of the second spacer element in a direction perpendicular to the optical axis, and CT2 is the center thickness of the second lens on the optical axis. The conditional expression 0.15<|d2s-d2m| / CT2<1.55 describes the proportional relationship between the difference between the inner diameter d2s of the first side surface and the inner diameter d2m of the second side surface of the second spacer element in the optical system and the center thickness CT2 of the second lens on the optical axis. This proportional relationship has many effects on the design and performance of the optical system. The following is a brief analysis of its effectiveness: By controlling the ratio between the difference between the inner diameters of the two sides of the second spacer element and the center thickness of the second lens, a more compact optical system can be designed while maintaining system performance. A smaller ratio (i.e., |d2s-d2m| is smaller relative to CT2) may mean a more compact layout, which helps to reduce the overall volume of the system. The difference in the inner diameters of the two sides of the second spacing element will affect the transmission path and shading of the light. The appropriate ratio helps to reduce the shading of the light at the edge of the second spacing element, improve the utilization of light and the imaging quality. By optimizing this ratio, the complexity and manufacturing cost of the system can be reduced while ensuring the imaging quality and system stability.

[0066] In an exemplary embodiment, the optical system of the present application may satisfy: 1.25≤CT2 / CT1<1.80, wherein CT2 is the center thickness of the second lens on the optical axis, and CT1 is the center thickness of the first lens on the optical axis. Satisfying 1.25≤CT2 / CT1<1.80, by controlling the ratio of the center thickness of the first lens and the second lens, a more compact optical system can be designed while maintaining the system performance. When CT2 and CT1 are within this ratio range, the thickness of the second lens will not be too thick or too thin relative to the first lens, which helps to maintain the overall compactness of the system. The thickness of the lens will affect its optical performance, including aberration correction and light transmission efficiency. An appropriate lens thickness ratio helps to obtain better imaging quality while maintaining the compactness of the system. A lens that is too thick or too thin may cause increased aberrations or reduced light transmission efficiency. The thickness of the lens also affects its mechanical stability. When CT2 and CT1 are within this ratio range, the thickness of the two lenses is relatively balanced, which helps to enhance the mechanical stability of the system and reduce performance degradation caused by vibration or impact. The thickness of the lens will also affect its manufacturing cost. Within this ratio range of CT2 and CT1, the thickness of the two lenses is relatively moderate, which helps to reduce manufacturing costs while maintaining the performance of the system.

[0067] In an exemplary embodiment, the optical system of the present application may satisfy: -6.20 < R4 / f < -5.60, where R4 is the radius of curvature of the second side of the second lens, and f is the effective focal length of the optical system. Satisfying -6.20 < R4 / f < -5.60, the ratio of the radius of curvature of the second side of the second lens to the focal length of the optical system directly affects the aberration correction of the system, including spherical aberration, coma aberration, etc. When R4 and f are within this ratio range, the system may have better aberration correction ability, thereby obtaining higher-quality imaging. A larger absolute value of the ratio of R4 to f may mean a shorter focal length and a more compact lens layout, which is particularly important for optical devices that require miniaturization or lightweight. The ratio of the radius of curvature of the second side of the second lens to the focal length of the optical system also affects the focal length adjustment range of the system. By adjusting the ratio of R4 to f, it is possible to provide a larger zoom ability or a wider focal length range while maintaining the compactness of the system. The radius of curvature of the lens affects the light transmission path and focusing effect. When the radius of curvature of the second side of the second lens is within this ratio range, the system may have higher light transmission efficiency, thereby reducing the reflection and scattering losses of light on the lens surface, which helps to improve the imaging brightness and contrast of the system.

[0068] In an exemplary embodiment, the optical system of the present 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 set at an appropriate position in the optical system. For example, the aperture stop can be located on the first side of the first lens.

[0069] In an exemplary embodiment, the effective focal length f of the optical system can be, for example, in the range of 16.9 mm to 18.2 mm, the effective focal length f1 of the first lens group can be, for example, in the range of 49.6 mm to 58.8 mm, and the optical power F2 of the optical element group composed of the reflective polarizing element, the first quarter-wave plate, and the second lens can be, for example, in the range of 21.5 mm to 23.1 mm.

[0070] According to some embodiments of the present application, the optical system of the present application is a small-volume optical system with high-definition imaging quality. In applications, the optical system according to the exemplary embodiment of the present application can be applied to VR devices. By reasonably designing the structural arrangement of the lens, the reflective polarizing element, the quarter-wave plate, the partial reflection layer, and the lens barrel, and reasonably setting the spacer elements between the lenses, it is possible to reduce the volume and weight of the system while ensuring the image quality, improve the light energy utilization efficiency, and thus provide a more comfortable and high-quality virtual reality experience for users.

[0071] The following takes the optical system applied to, for example, a VR device, with the first side being the human eye side and the second side being the screen side, and further describes specific embodiments of the optical system applicable to the above embodiments with reference to the accompanying drawings. Embodiment 1

[0072] The following reference Figure 2 An optical system according to Embodiment 1 of the present application is described. Figure 2 It is a schematic diagram of the structure of the optical system according to Example 1 of the present application.

[0073] like Figure 2 As shown, the optical system of Example 1 includes a lens barrel P0 and a lens group and a spacer element group disposed in the lens barrel P0. The lens group includes an aperture STO (not shown), a first lens E1, a reflective polarizing element RP, a first quarter wave plate QWP1, a second lens E2, a partial reflection layer BS, an anti-reflection film AR, a second quarter wave plate QWP2, a linear polarizing plate LP, a protective glass GL and an image surface (not shown) in order from the side close to the human eye to the side close to the screen along the optical axis. Among them, the anti-reflection film AR, the second quarter wave plate QWP2, the linear polarizing plate LP and the protective glass GL are attached together in order from the side close to the human eye to the side close to the screen.

[0074] The first lens E1 has positive focal power, and its side near the human eye is convex, and its side near the screen is flat. The second lens E2 has positive focal power, and its side near the human eye is flat, and its side near the screen is convex. Among them, the reflective polarizing element RP is attached to the side near the human eye of the first quarter wave plate QWP1, and the first quarter wave plate QWP1 is attached to the side near the human eye of the second lens E2. The partial reflection element BS can have a semi-transmissive and semi-reflective function and is attached to the side near the screen of the second lens E2.

[0075] In this example, the light emitted from the image plane passes through the protective glass GL, the linear polarizer LP, the second quarter-wave plate QWP2, the anti-reflection film AR, the second lens E2, the first quarter-wave plate QWP1 in sequence to reach the reflective polarizer RP, is reflected at the reflective polarizer RP and passes through the first quarter-wave plate QWP1 and the second lens E2 again to reach the near-screen side of the second lens E2, and then the light beam is reflected again at the partial reflection layer BS on the near-screen side of the second lens E2 and passes through the second lens E2, the first quarter-wave plate QWP1, the reflective polarizer RP, the first lens E1 in sequence, passes through the aperture STO and is finally emitted toward the human eye side.

[0076] Table 1 shows the basic parameters of the optical system of Example 1, where the units of the radius of curvature and thickness / distance are both in millimeters (mm). Table 1 only lists the correspondence between the surface numbers of some surfaces and some components. Due to the problem of common surfaces between adjacent components, it is not convenient to mark all components in Table 1 with common surfaces.

[0077] Table 1

[0078]

[0079] In Example 1, the side of the first lens E1 near the human eye is an even-order polynomial aspheric surface, and the side of the second lens E2 near the screen is an odd-order polynomial aspheric surface. The surface shapes of the even-order polynomial aspheric surface and the odd-order polynomial aspheric surface can be defined by, but not limited to, the following aspheric formula:

[0080] (1)

[0081] Wherein, x is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of h along the optical axis; c is the paraxial curvature of the aspheric surface, c=1 / R (i.e., the paraxial curvature c is the reciprocal of the curvature radius R in Table 1 above); k is the cone coefficient; Ai is the correction coefficient of the i-th order of the aspheric surface, when formula (1) limits the aspheric surface of an even-order polynomial, i can be, for example, an even number between 4 and 20. When formula (1) limits the aspheric surface of an odd-order polynomial, i can be, for example, a natural number between 1 and 27.

[0082] The following Table 2-1 gives the cone coefficient k and high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 that can be used for the even-order polynomial aspheric mirror surface in Example 1.

[0083] Table 2-1

[0084]

[0085] Table 2-2 below gives the coefficients of higher order terms A1 to A27 that can be used for the odd-order polynomial aspheric surface in Example 1.

[0086] Table 2-2

[0087]

[0088] Table 3 shows some basic parameters of the optical system of Example 1, such as f, f1, F2, DT11, DT21, SAG11 and SAG22. The units of each parameter in Table 3 are millimeters (mm).

[0089] Table 3

[0090]

[0091] like Figure 2 As shown, the optical system of Example 1 further includes two spacer elements, namely a first spacer element P1 and a second spacer element P2. The first spacer element P1 is placed between the first lens and the second lens and is disposed against the side of the first lens near the screen, and the second spacer element P2 is disposed against the side of the second lens near the screen. Table 4 shows a basic parameter table of the spacer elements of the optical system, and the units of each parameter in Table 4 are millimeters (mm).

[0092] Table 4

[0093] Example 2

[0094] The following reference Figure 3 An optical system according to Embodiment 2 of the present application is described. Figure 3 It is a schematic diagram of the structure of the optical system according to Example 2 of the present application.

[0095] In this embodiment and Embodiment 3, for the sake of brevity, some descriptions similar to Embodiment 1 will be omitted.

[0096] like Figure 3 As shown, the optical system includes a lens barrel P0 and a lens group and a spacer element group placed in the lens barrel P0. The lens group includes an aperture STO (not shown), a first lens E1, a reflective polarizing element RP, a first quarter wave plate QWP1, a second lens E2, a partial reflection layer BS, an anti-reflection film AR, a second quarter wave plate QWP2, a linear polarizer LP, a protective glass GL and an image surface in sequence from the side close to the human eye to the side close to the screen along the optical axis. Among them, the anti-reflection film AR, the second quarter wave plate QWP2, the linear polarizer LP and the protective glass GL are attached together in sequence from the side close to the human eye to the side close to the screen. The lens group of Example 2 is exactly the same as the lens group of Example 1, and will not be repeated. The basic parameters of the optical system of Example 2 are detailed in Tables 1 to 3, and will not be repeated.

[0097] like Figure 3 As shown, the optical system of Example 2 further includes two spacing elements, namely a first spacing element P1 and a second spacing element P2. The first spacing element P1 is placed between the first lens and the second lens and is disposed against the side of the first lens near the screen, and the second spacing element P2 is disposed against the side of the second lens near the screen. Table 5 shows a basic parameter table of the spacing elements of the optical system, and the units of each parameter in Table 5 are millimeters (mm).

[0098] Table 5

[0099] Example 3

[0100] The following reference Figure 4 An optical system according to Example 3 of the present application is described. Figure 4 It is a schematic diagram of the structure of the optical system according to Example 3 of the present application.

[0101] like Figure 4As shown, the optical system of Example 3 includes a lens barrel P0 and a lens group and a spacer element group placed in the lens barrel P0. The lens group includes an aperture STO (not shown), a first lens E1, a reflective polarizing element RP, a first quarter wave plate QWP1, a second lens E2, a partial reflection layer BS, an anti-reflection film AR, a second quarter wave plate QWP2, a linear polarizer LP, a protective glass GL and an image surface in sequence from the side close to the human eye to the side close to the screen along the optical axis. Among them, the anti-reflection film AR, the second quarter wave plate QWP2, the linear polarizer LP and the protective glass GL are attached together in sequence from the side close to the human eye to the side close to the screen. The lens group of Example 3 is exactly the same as the lens group of Example 1, and will not be repeated. The basic parameters of the optical system of Example 3 are detailed in Tables 1 to 3, and will not be repeated.

[0102] like Figure 4 As shown, the optical system of Example 3 further includes two spacing elements, namely a first spacing element P1 and a second spacing element P2. The first spacing element P1 is placed between the first lens and the second lens and is disposed against the side of the first lens near the screen, and the second spacing element P2 is disposed against the side of the second lens near the screen. Table 6 shows a basic parameter table of the spacing elements of the optical system, and the units of each parameter in Table 6 are millimeters (mm).

[0103] Table 6

[0104] Example 4

[0105] The following reference Figure 5 An optical system according to Example 4 of the present application is described. Figure 5 It is a schematic diagram of the structure of the optical system according to Example 1 of the present application.

[0106] like Figure 5 As shown, the optical system includes a lens barrel P0 and a lens group and a spacer element group disposed in the lens barrel P0. The lens group includes an aperture STO (not shown), a first lens E1, a reflective polarizing element RP, a first quarter wave plate QWP1, a second lens E2, a partial reflection layer BS, an anti-reflection film AR, a second quarter wave plate QWP2, a linear polarizing plate LP, a protective glass GL and an image surface in order from the side close to the human eye to the side close to the screen along the optical axis. Among them, the anti-reflection film AR, the second quarter wave plate QWP2, the linear polarizing plate LP and the protective glass GL are attached together in order from the side close to the human eye to the side close to the screen.

[0107] The first lens E1 has positive focal power, and its side near the human eye is convex, and its side near the screen is convex. The second lens E2 has positive focal power, and its side near the human eye is concave, and its side near the screen is convex. Among them, the reflective polarizing element RP is attached to the side near the human eye of the first quarter wave plate QWP1, and the first quarter wave plate QWP1 is attached to the side near the human eye of the second lens E2. The partial reflection element BS can have a semi-transmissive and semi-reflective function and is attached to the side near the screen of the second lens E2.

[0108] In this example, the light emitted from the image plane passes through the protective glass GL, the linear polarizer LP, the second quarter-wave plate QWP2, the anti-reflection film AR, the second lens E2, the first quarter-wave plate QWP1 in sequence to reach the reflective polarizer RP, is reflected at the reflective polarizer RP and passes through the first quarter-wave plate QWP1 and the second lens E2 again to reach the near-screen side of the second lens E2, and then the light beam is reflected again at the partial reflection layer BS on the near-screen side of the second lens E2 and passes through the second lens E2, the first quarter-wave plate QWP1, the reflective polarizer RP, the first lens E1 in sequence, passes through the aperture STO and is finally emitted toward the human eye side.

[0109] Table 7 shows the basic parameters of the optical system of Example 4, where the units of the radius of curvature and thickness / distance are both in millimeters (mm). Table 7 only lists the correspondence between the surface numbers of some surfaces and some components. Since there are common surfaces between adjacent components, it is not convenient to mark all components in Table 7 with common surfaces.

[0110] Table 7

[0111]

[0112] In Example 4, the side surface near the human eye and the side surface near the screen of the first lens E1 and the side surface near the human eye of the second lens E2 are even-order polynomial aspheric surfaces. Table 8-1 shows the conic coefficient k and high-order coefficients of each even-order polynomial aspheric mirror surface that can be used in Example 4, wherein the surface shape of each even-order polynomial aspheric surface can be defined by the formula (1) given in the above Example 1, and i can be an even number between 4 and 20, for example.

[0113] Table 8-1

[0114]

[0115] In Example 4, the side surface of the second lens E2 near the screen is an odd-order polynomial aspheric surface. The surface shape of the odd-order polynomial aspheric lens can be defined by, but not limited to, the above-mentioned aspheric formula (1), and i can be, for example, a natural number between 1 and 27. The following Table 8-2 lists the high-order coefficients A1 to A27 of the odd-order polynomial aspheric surface that can be used in Example 4.

[0116] Table 8-2

[0117]

[0118] Table 9 shows some basic parameters of the optical system of Example 4, such as f, f1, F2, DT11, DT21, SAG11 and SAG22. The units of each parameter in Table 9 are millimeters (mm).

[0119] Table 9

[0120]

[0121] like Figure 5 As shown, the optical system of Example 4 further includes two spacing elements, namely a first spacing element P1 and a second spacing element P2. The first spacing element P1 is placed between the first lens and the second lens and is disposed against the side of the first lens near the screen, and the second spacing element P2 is disposed against the side of the second lens near the screen. Table 10 shows a basic parameter table of the spacing elements of the optical system, and the units of each parameter in Table 10 are millimeters (mm).

[0122] Table 10

[0123] Example 5

[0124] The following reference Figure 6 An optical system according to Example 5 of the present application is described. Figure 6 It is a schematic diagram of the structure of the optical system according to Example 5 of the present application.

[0125] In this embodiment and Embodiment 6, for the sake of brevity, some descriptions similar to Embodiment 4 will be omitted.

[0126] like Figure 6 As shown, the optical system of Example 5 includes a lens barrel P0 and a lens group and a spacer element group placed in the lens barrel P0. The lens group includes an aperture STO (not shown), a first lens E1, a reflective polarizing element RP, a first quarter wave plate QWP1, a second lens E2, a partial reflection layer BS, an anti-reflection film AR, a second quarter wave plate QWP2, a linear polarizer LP, a protective glass GL and an image surface in sequence from the side close to the human eye to the side close to the screen along the optical axis. Among them, the anti-reflection film AR, the second quarter wave plate QWP2, the linear polarizer LP and the protective glass GL are attached together in sequence from the side close to the human eye to the side close to the screen. The lens group of Example 5 is exactly the same as the lens group of Example 4, and will not be repeated. The basic parameters of the optical system of Example 5 are detailed in Tables 7 to 9, and will not be repeated.

[0127] like Figure 6As shown, the optical system of Example 5 further includes two spacing elements, namely a first spacing element P1 and a second spacing element P2. The first spacing element P1 is placed between the first lens and the second lens and is disposed against the side of the first lens near the screen, and the second spacing element P2 is disposed against the side of the second lens near the screen. Table 11 shows a basic parameter table of the spacing elements of the optical system, and the units of each parameter in Table 11 are millimeters (mm).

[0128] Table 11

[0129] Example 6

[0130] The following reference Figure 7 An optical system according to Example 6 of the present application is described. Figure 7 It is a schematic diagram of the structure of the optical system according to Example 6 of the present application.

[0131] like Figure 7 As shown, the optical system of Example 6 includes a lens barrel P0 and a lens group and a spacer element group placed in the lens barrel P0. The lens group includes an aperture STO (not shown), a first lens E1, a reflective polarizing element RP, a first quarter wave plate QWP1, a second lens E2, a partial reflection layer BS, an anti-reflection film AR, a second quarter wave plate QWP2, a linear polarizer LP, a protective glass GL and an image surface in sequence from the side close to the human eye to the side close to the screen along the optical axis. Among them, the anti-reflection film AR, the second quarter wave plate QWP2, the linear polarizer LP and the protective glass GL are attached together in sequence from the side close to the human eye to the side close to the screen. The lens group of Example 6 is exactly the same as the lens group of Example 4, and will not be repeated. The basic parameters of the optical system of Example 6 are detailed in Tables 7 to 9, and will not be repeated.

[0132] like Figure 7 As shown, the optical system of Example 6 further includes two spacing elements, namely a first spacing element P1 and a second spacing element P2. The first spacing element P1 is placed between the first lens and the second lens and is disposed against the side of the first lens near the screen, and the second spacing element P2 is disposed against the side of the second lens near the screen. Table 12 shows a basic parameter table of the spacing elements of the optical system, and the units of each parameter in Table 12 are millimeters (mm).

[0133] Table 12

[0134] Example 7

[0135] The following reference Figure 8 An optical system according to Example 7 of the present application is described. Figure 8 It is a schematic diagram of the structure of the optical system according to Example 1 of the present application.

[0136] like Figure 8 As shown, the optical system includes a lens barrel P0 and a lens group and a spacer element group disposed in the lens barrel P0. The lens group includes an aperture STO (not shown), a first lens E1, a reflective polarizing element RP, a first quarter wave plate QWP1, a second lens E2, a partial reflection layer BS, an anti-reflection film AR, a second quarter wave plate QWP2, a linear polarizing plate LP, a protective glass GL and an image surface in order from the side close to the human eye to the side close to the screen along the optical axis. Among them, the anti-reflection film AR, the second quarter wave plate QWP2, the linear polarizing plate LP and the protective glass GL are attached together in order from the side close to the human eye to the side close to the screen.

[0137] The first lens E1 has positive focal power, and its side near the human eye is convex, and its side near the screen is convex. The second lens E2 has positive focal power, and its side near the human eye is concave, and its side near the screen is convex. Among them, the reflective polarizing element RP is attached to the side near the human eye of the first quarter wave plate QWP1, and the first quarter wave plate QWP1 is attached to the side near the human eye of the second lens E2. The partial reflection element BS can have a semi-transmissive and semi-reflective function and is attached to the side near the screen of the second lens E2.

[0138] In this example, the light emitted from the image plane passes through the protective glass GL, the linear polarizer LP, the second quarter-wave plate QWP2, the anti-reflection film AR, the second lens E2, the first quarter-wave plate QWP1 in sequence to reach the reflective polarizer RP, is reflected at the reflective polarizer RP and passes through the first quarter-wave plate QWP1 and the second lens E2 again to reach the near-screen side of the second lens E2, and then the light beam is reflected again at the partial reflection layer BS on the near-screen side of the second lens E2 and passes through the second lens E2, the first quarter-wave plate QWP1, the reflective polarizer RP, the first lens E1 in sequence, passes through the aperture STO and is finally emitted toward the human eye side.

[0139] Table 13 shows the basic parameters of the optical system of Example 7, where the units of the radius of curvature and thickness / distance are both in millimeters (mm). Table 13 only lists the correspondence between the surface numbers of some surfaces and some components. Since there are common surfaces between adjacent components, it is not convenient to mark all components in Table 13.

[0140] Table 13

[0141]

[0142] In Example 7, the side surface near the human eye and the side surface near the screen of the first lens E1 are even-order polynomial aspheric surfaces. Table 14-1 shows the conic coefficient k and high-order coefficients of each even-order polynomial aspheric mirror surface that can be used in Example 7, wherein the surface shape of each even-order polynomial aspheric surface can be defined by the formula (1) given in the above Example 1, and i can be an even number in the range of 4 to 20, for example.

[0143] Table 14-1

[0144]

[0145] In Example 7, the side surface of the second lens E2 near the screen is an odd-order polynomial aspheric surface. The surface shape of the odd-order polynomial aspheric lens can be defined by, but not limited to, the above-mentioned aspheric formula (1). i can be, for example, a natural number between 1 and 27. The following Table 14-2 lists the high-order coefficients A1 to A27 of the odd-order polynomial aspheric surface that can be used in Example 7.

[0146] Table 14-2

[0147]

[0148] Table 15 shows some basic parameters of the optical system of Example 7, such as f, f1, F2, DT11, DT21, SAG11 and SAG22. The units of each parameter in Table 15 are millimeters (mm).

[0149] Table 15

[0150]

[0151] like Figure 8 As shown, the optical system of Example 7 further includes two spacing elements, namely a first spacing element P1 and a second spacing element P2. The first spacing element P1 is placed between the first lens and the second lens and is disposed against the side of the first lens near the screen, and the second spacing element P2 is disposed against the side of the second lens near the screen. Table 16 shows a basic parameter table of the spacing elements of the optical system, and the units of each parameter in Table 16 are millimeters (mm).

[0152] Table 16

[0153] Example 8

[0154] The following reference Fig. 9 An optical system according to Example 8 of the present application is described. Fig. 9 It is a schematic diagram of the structure of the optical system according to Example 8 of the present application.

[0155] In this embodiment and Embodiment 9, for the sake of brevity, some descriptions similar to Embodiment 4 will be omitted.

[0156] like Fig. 9 As shown, the optical system of Example 8 includes a lens barrel P0 and a lens group and a spacer element group placed in the lens barrel P0. The lens group includes an aperture STO (not shown), a first lens E1, a reflective polarizing element RP, a first quarter wave plate QWP1, a second lens E2, a partial reflection layer BS, an anti-reflection film AR, a second quarter wave plate QWP2, a linear polarizer LP, a protective glass GL and an image surface in sequence from the side close to the human eye to the side close to the screen along the optical axis. Among them, the anti-reflection film AR, the second quarter wave plate QWP2, the linear polarizer LP and the protective glass GL are attached together in sequence from the side close to the human eye to the side close to the screen. The lens group of Example 8 is exactly the same as the lens group of Example 4, and will not be repeated here. The basic parameters of the optical system of Example 8 are detailed in Tables 13 to 15, and will not be repeated here.

[0157] like Fig. 9 As shown, the optical system of Example 8 further includes two spacing elements, namely a first spacing element P1 and a second spacing element P2. The first spacing element P1 is placed between the first lens and the second lens and is disposed against the side of the first lens near the screen, and the second spacing element P2 is disposed against the side of the second lens near the screen. Table 17 shows a basic parameter table of the spacing elements of the optical system, and the units of each parameter in Table 17 are millimeters (mm).

[0158] Table 17

[0159] Example 9

[0160] The following reference Fig.10 An optical system according to Example 9 of the present application is described. Fig.10 It is a schematic diagram of the structure of the optical system according to Example 9 of the present application.

[0161] like Fig.10 As shown, the optical system of Example 9 includes a lens barrel P0 and a lens group and a spacer element group placed in the lens barrel P0. The lens group includes an aperture STO (not shown), a first lens E1, a reflective polarizing element RP, a first quarter wave plate QWP1, a second lens E2, a partial reflection layer BS, an anti-reflection film AR, a second quarter wave plate QWP2, a linear polarizer LP, a protective glass GL and an image surface in sequence from the side close to the human eye to the side close to the screen along the optical axis. Among them, the anti-reflection film AR, the second quarter wave plate QWP2, the linear polarizer LP and the protective glass GL are attached together in sequence from the side close to the human eye to the side close to the screen. The lens group of Example 9 is exactly the same as the lens group of Example 4, and will not be repeated. The basic parameters of the optical system of Example 9 are detailed in Tables 13 to 15, and will not be repeated.

[0162] like Fig.10As shown, the optical system of Example 9 further includes two spacing elements, namely a first spacing element P1 and a second spacing element P2. The first spacing element P1 is placed between the first lens and the second lens and is disposed against the side of the first lens near the screen, and the second spacing element P2 is disposed against the side of the second lens near the screen. Table 18 shows a basic parameter table of the spacing elements of the optical system, and the units of each parameter in Table 18 are millimeters (mm).

[0163] Table 18

[0164]

[0165] In summary, the optical systems of Examples 1 to 9 satisfy the relationship shown in Table 19.

[0166] Table 19

[0167]

[0168] The present application also provides an optical device, which may be an independent projection device such as a projector, or a projection module integrated in a mobile electronic device such as a VR. The optical device is equipped with the optical system described above.

[0169] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of protection involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the concept of the present application. For example, the above features are replaced with the technical features with similar functions disclosed in the present application (but not limited to) to form a technical solution.

Claims

1. An optical system, characterized in that Comprising: A lens group, which sequentially includes, from the first side to the second side along the optical axis: a first lens, a reflective polarizing element, a first quarter-wave plate, and a second lens, wherein the first lens has a positive optical power, and the second lens has a positive optical power; the optical element group composed of the reflective polarizing element, the first quarter-wave plate, and the second lens has a positive optical power; A spacer element group, including a first spacer element disposed between the first lens and the second lens and abutting against the second side surface of the first lens; and A lens barrel for accommodating the lens group and the spacer element group; wherein, The optical system satisfies: 0.05 < |d1s - d0s| / CT1 < 2.15, where d1s is the maximum inner diameter of the first side surface of the first spacer element in the direction perpendicular to the optical axis, d0s is the maximum inner diameter of the first side end surface of the lens barrel in the direction perpendicular to the optical axis, and CT1 is the central thickness of the first lens on the optical axis; The optical system satisfies: 1.25 < f1 / R1 ≤ 1.50, where f1 is the effective focal length of the first lens, and R1 is the curvature radius of the first side surface of the first lens.

2. The optical system according to claim 1, characterized in that The optical system satisfies: 0.65 < f / L < 1.05, where f is the effective focal length of the optical system, and L is the maximum distance along the optical axis from the first side end surface to the second side end surface of the lens barrel.

3. The optical system according to claim 1, characterized in that The optical system further includes a second spacer element abutting against the second side surface of the second lens, The optical system satisfies: 0.35 < EP12 / CT2 ≤ 0.50, where EP12 is the distance along the optical axis between the second side surface of the first spacer element and the first side surface of the second spacer element, and CT2 is the central thickness of the second lens on the optical axis.

4. The optical system according to claim 1, characterized in that The optical system satisfies: 0.70 < d0s / 2 / DT11 < 0.90, where DT11 is the maximum effective radius of the first side surface of the first lens.

5. The optical system according to claim 1, characterized in that The optical system satisfies: 0.30 < |SAG11| / |SAG22| ≤ 0.90, where SAG11 is the axial distance between the intersection of the first side surface of the first lens and the optical axis and the vertex of the effective radius of the first side surface of the first lens, and SAG22 is the axial distance between the intersection of the second side surface of the second lens and the optical axis and the vertex of the effective radius of the second side surface of the second lens.

6. The optical system according to claim 1, characterized in that The optical system further includes a second spacer element abutting against the second side surface of the second lens, The optical system satisfies: 1.10 ≤ CP2 / CT2 < 1.50, where CP2 is the maximum thickness of the second spacer element along the optical axis, and CT2 is the central thickness of the second lens on the optical axis.

7. The optical system according to claim 1, characterized in that The optical system further includes a second spacer element abutting against the second side surface of the second lens, The optical system satisfies: 1.05 < D2s / DT21 < 2.65, where D2s is the maximum outer diameter of the first side surface of the second spacer element in a direction perpendicular to the optical axis, and DT21 is the maximum effective radius of the first side surface of the second lens.

8. The optical system according to any one of claims 1 to 7, characterized in that: The optical system further includes a second spacer element disposed against the second side surface of the second lens. The optical system satisfies: 1.05 < D0m / D2m ≤ 1.15, where D0m is the maximum outer diameter of the second side surface of the lens barrel in a direction perpendicular to the optical axis, and D2m is the maximum outer diameter of the second side surface of the second spacer element in a direction perpendicular to the optical axis.

9. The optical system according to any one of claims 1 to 7, characterized in that: The optical system satisfies: 1.50 < L / (CT1 + CT2) < 2.30, where L is the maximum distance from the first side end surface to the second side end surface of the lens barrel along the optical axis, and CT2 is the central thickness of the second lens on the optical axis.

10. The optical system according to any one of claims 1 to 7, wherein The optical system satisfies: -5.00 < R4 / F2 < -4.40, where R4 is the radius of curvature of the second side surface of the second lens, and F2 is the optical power of the optical element group.

11. The optical system according to any one of claims 1 to 7, characterized in that: The optical system further includes a second spacer element disposed against the second side surface of the second lens. The optical system satisfies: 2.80 < d1s / f1 + d2s / F2 < 3.10, where f1 is the effective focal length of the first lens, d2s is the maximum inner diameter of the first side surface of the second spacer element in a direction perpendicular to the optical axis, and F2 is the optical power of the optical element group.

12. The optical system according to any one of claims 1 to 7, characterized in that: The optical system further includes a second spacer element disposed against the second side surface of the second lens. The optical system satisfies: 0.15 < |d2s - d2m| / CT2 < 1.55, where d2s is the maximum inner diameter of the first side surface of the second spacer element in a direction perpendicular to the optical axis, d2m is the maximum inner diameter of the second side surface of the second spacer element in a direction perpendicular to the optical axis, and CT2 is the central thickness of the second lens on the optical axis.

13. The optical system according to any one of claims 1 to 7, characterized in that: The optical system satisfies: 1.25 ≤ CT2 / CT1 < 1.80, where CT2 is the central thickness of the second lens on the optical axis.

14. The optical system according to any one of claims 1 to 7, characterized in that: The optical system satisfies: -6.20 < R4 / f < -5.60, where R4 is the radius of curvature of the second side surface of the second lens, and f is the effective focal length of the optical system.

15. An optical device, characterized in that: An optical system including any one of claims 1 to 14.

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