Optical system

Abstract

The application discloses an optical system, which comprises a lens barrel, a first element group, a second element group and a third element group arranged in sequence along an optical axis from a first side to a second side in the lens barrel, the first element group comprises a first lens, the second element group comprises a second lens, and the third element group comprises a third lens with negative optical power; the optical system further comprises a reflective polarizing element and a quarter-wave plate, wherein the reflective polarizing element is arranged in any one of the first element group to the third element group, and the quarter-wave plate is arranged in any one of the first element group to the third element group; an outer diameter of a second side end surface of the lens barrel is less than 60.0 mm, and a curvature radius R6 of a second side surface of the third lens and an outer diameter D0m of the second side end surface of the lens barrel satisfy R6 / D0m<‑1.0.

Description

Technical Field

[0001] This application relates to the field of optical devices, specifically to a three-piece optical system. Background Technology

[0002] Virtual Reality (VR) technology plays a vital role in the entertainment market, primarily gaming, as well as in education and training, arts and culture, remote work collaboration, and healthcare. VR devices are consequently gaining popularity among users. The miniaturization and high image quality of VR devices are key factors influencing the user experience.

[0003] In the actual design process of the optical system of VR devices, the parameters and their matching relationship of the lens and the end face of the lens barrel near the display are easily overlooked. When the above parameters and their matching relationship are not designed properly, the optical system will have a large size and poor image quality. For example, the image of the optical system is prone to blurring or distortion when magnified due to the limitation of resolution and clarity. It is also easy to cause dizziness and nausea in users when used for a long time. In addition, the large size can also increase the burden on users and seriously affect the user's experience.

[0004] Therefore, how to provide a miniaturized optical system with high imaging quality to improve the user experience has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This application provides an optical system that can at least solve or partially solve at least one problem or other problems existing in the prior art.

[0006] One aspect of this application provides an optical system comprising a lens barrel and a first element group, a second element group, and a third element group arranged sequentially along the optical axis from a first side to a second side within the lens barrel. The first element group includes a first lens, the second element group includes a second lens, and the third element group includes a third lens with negative optical power. The optical system further includes a reflective polarizing element and a quarter-wave plate, wherein the reflective polarizing element is placed in any of the first to third element groups, and the quarter-wave plate is placed in any of the first to third element groups. The outer diameter of the second side end face of the lens barrel is less than 60.0 mm, and the radius of curvature R6 of the second side face of the third lens satisfies R6 / D0m < -1.0 with respect to the outer diameter D0m of the second side end face of the lens barrel.

[0007] According to an exemplary embodiment of this application, at least one of the first lens, the second lens, and the third lens has its first or second side surface configured as a plane.

[0008] According to an exemplary embodiment of this application, a reflective polarizing element is placed in a first element group or a second element group, and a quarter-wave plate is placed in the first element group or the second element group.

[0009] According to an exemplary embodiment of this application, the radius of curvature R5 of the first side surface of the third lens, the radius of curvature R6 of the second side surface of the third lens, the inner diameter d0m of the second side end face of the lens barrel and the outer diameter D0m of the second side end face of the lens barrel satisfy: 10.0<(R5-R6) / (D0m-d0m)<50.0.

[0010] According to an exemplary embodiment of this application, the optical system further includes an image surface disposed on the second side, and the distance TL from the first side of the first element group to the image surface on the optical axis satisfies the following condition: TL / f < 1.0.

[0011] According to an exemplary embodiment of this application, the optical system further includes a second spacer element disposed on and in contact with the second side surface of the second lens, wherein the effective focal length f3 of the third element group and the distance EP02 along the optical axis between the first side end face of the lens barrel and the second spacer element satisfy: -20.0 <f3 / EP02<-5.0。

[0012] According to an exemplary embodiment of this application, the optical system further includes a second spacer element disposed on and in contact with the second side surface of the second lens, wherein the radius of curvature R5 of the first side surface of the third lens, the radius of curvature R6 of the second side surface of the third lens, the outer diameter D2s of the first side surface of the second spacer element, and the outer diameter D2m of the second side surface of the second spacer element satisfy: -5.0 <R5 / D2s+R6 / D2m<0。

[0013] According to an exemplary embodiment of this application, the optical system further includes an image surface disposed on the second side. The inner diameter d0m of the second side end face of the lens barrel, the outer diameter D0m of the second side end face of the lens barrel, the distance BL from the second side surface of the third lens to the image surface on the optical axis and half of the maximum field of view of the optical system, Semi-FOV, satisfy: 1.0 < (D0m - d0m) / (BL × tan(Semi-FOV)) < 20.0.

[0014] According to an exemplary embodiment of this application, the optical system further includes a second spacer element disposed on and in contact with the second side surface of the second lens, wherein the refractive index N1 of the first lens, the refractive index N2 of the second lens, and the refractive index N of the reflective polarizing element are... R The refractive index N of a quarter-wave plate QThe center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, and the distance EP02 between the first side end face of the lens barrel and the second spacer element along the optical axis satisfy: 2.0 < (N1 + N2 + N R +N Q )×(CT1+CT2) / EP02<10.0.

[0015] According to an exemplary embodiment of this application, the optical system further includes a second spacer element disposed on and in contact with the second side surface of the second lens, wherein the center thickness CT3 of the third lens on the optical axis, the length L of the lens barrel in the direction of the optical axis, and the distance EP02 between the first side end face of the lens barrel and the second spacer element along the optical axis satisfy: 3.0 < (L-EP02) / CT3 < 8.0.

[0016] According to an exemplary embodiment of this application, the optical system further includes a second spacer element disposed on and in contact with the second side of the second lens. The axial distance SAG31 between the intersection of the first side of the third lens and the optical axis and the effective half-aperture vertex of the first side of the third lens, the air gap T23 between the second element group and the third element group on the optical axis and the maximum thickness CP2 of the second spacer element satisfy: -20.0 < (SAG31 + T23) / CP2 < 5.0.

[0017] According to an exemplary embodiment of this application, the optical system further includes a second spacer element disposed on and in contact with the second side surface of the second lens, wherein the inner diameter d2m of the second side surface of the second spacer element, the maximum effective half-aperture DT22 of the second side surface of the second lens, and the maximum effective half-aperture DT31 of the first side surface of the third lens satisfy: 0.5 <d2m / (DT22+DT31)<1.5。

[0018] According to an exemplary embodiment of this application, the optical system further includes a first spacer element disposed between the first lens and the second lens, wherein the inner diameter d1m of the second side of the first spacer element and the effective focal length f2 of the second element group satisfy: 0 <d1m / f2<5.0。

[0019] According to an exemplary embodiment of this application, the optical system further includes a first spacer element disposed between the first lens and the second lens, wherein the maximum effective half-aperture DT12 of the second side of the first lens, the maximum effective half-aperture DT21 of the first side of the second lens, the inner diameter d1m of the second side of the first spacer element and the outer diameter D1m of the second side of the first spacer element satisfy: 1.0 < (DT12 + DT21) / (D1m - d1m) < 5.0.

[0020] The optical system provided in this application is configured as a three-piece folding system. By ensuring that the ratio between the radius of curvature of the second side surface of the third lens and the outer diameter of the second side end face of the lens barrel is less than -1.0, the second side surface of the third lens is constrained to be convex, preventing the convex shape from protruding excessively. This effectively controls the refraction angle of light at the third lens, avoiding excessive refraction angle and reducing the impact of the third lens on the overall imaging quality of the optical system. Simultaneously, it constrains the external dimensions of the second side end face of the lens barrel, ensuring that its outer diameter is less than 60.0 mm. This minimizes the external dimensions of the second side end face of the lens barrel while maintaining its manufacturability. This design helps to rationally control the fit between the third lens and the second side end face of the lens barrel, reducing the size of the optical system and facilitating miniaturization. It also reduces imaging quality problems such as poor resolution and sharpness caused by improper design at this location, lowers the risk of user dizziness and nausea, reduces user burden, and improves the user experience. Attached Figure Description

[0021] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0022] Figure 1 A schematic diagram of the parameters of the optical system according to this application is shown;

[0023] Figure 2 A schematic diagram of the structure of an optical system according to Embodiment 1 of the first embodiment of this application is shown;

[0024] Figure 3 A schematic diagram of the structure of an optical system according to Embodiment 2 of the first embodiment of this application is shown;

[0025] Figure 4 A schematic diagram of the structure of an optical system according to Embodiment 3 of the first embodiment of this application is shown;

[0026] Figures 5A to 5C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to the first embodiment of this application are shown respectively.

[0027] Figure 6 A schematic diagram of the structure of an optical system according to Embodiment 1 of the second embodiment of this application is shown;

[0028] Figure 7 A schematic diagram of the structure of an optical system according to Embodiment 2 of the second embodiment of this application is shown;

[0029] Figure 8A schematic diagram of the structure of an optical system according to Embodiment 3 of the second embodiment of this application is shown;

[0030] Figures 9A to 9C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to the second embodiment of this application are shown respectively.

[0031] Figure 10 A schematic diagram of the structure of an optical system according to Embodiment 1 of the third embodiment of this application is shown;

[0032] Figure 11 A schematic diagram of the structure of an optical system according to Embodiment 2 of the third embodiment of this application is shown;

[0033] Figure 12 A schematic diagram of the structure of an optical system according to Embodiment 3 of the third embodiment of this application is shown; and

[0034] Figures 13A to 13C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to the third embodiment of this application are shown respectively. Detailed Implementation

[0035] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements.

[0036] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0037] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not drawn strictly to scale.

[0038] In this paper, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the first side (e.g., the human eye side) is called the first side surface of the lens, and the surface of each lens closest to the second side (e.g., the display side) is called the second side surface of the lens.

[0039] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising" as used in this specification indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0040] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formalized sense, unless expressly so specified herein.

[0041] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] The features, principles and other aspects of this application are described in detail below.

[0043] like Figures 2 to 4 , Figures 6 to 8 as well as Figures 10 to 12 As shown, an optical system according to an exemplary embodiment of this application may include a lens barrel and a first element group, a second element group, and a third element group arranged sequentially along the optical axis from a first side to a second side within the lens barrel. The first element group may include, for example, a first lens, the second element group may include, for example, a second lens, and the third element group may include, for example, a third lens with negative optical power.

[0044] In an exemplary embodiment, the optical system may further include a reflective polarizing element and a quarter-wave plate. The reflective polarizing element may be placed in any of the first to third element groups. The quarter-wave plate may be placed in any of the first to third element groups. As an example, the reflective polarizing element may be placed in either the first or second element group, and the quarter-wave plate may be placed in either the first or second element group. The quarter-wave plate can change the polarization state of light, and in conjunction with the reflective polarizing element, it can achieve optical path refraction, which is beneficial for reducing the overall length and volume of the optical system.

[0045] In an exemplary embodiment, the optical system may further include a partially reflective layer, which may, for example, be attached to a second side surface of the third lens. The partially reflective layer has a semi-transmissive and semi-reflective effect on light.

[0046] In an exemplary embodiment, the first side may be, for example, the eye side, and the second side may be, for example, the display side. Accordingly, the first side of each element (first lens, second lens, third lens, reflective polarizing element, quarter-wave plate or partial reflective layer) may be referred to as the eye-side side, and the second side may be referred to as the display-side side.

[0047] In an exemplary embodiment, at least one of the first, second, and third lenses has its first or second side surface configured as a plane. As an example, the second side surface of the first lens and / or the first side surface of the second lens is configured as a plane. By constraining the shapes of the first to third lenses, the assembly and attachment difficulty of at least one of the reflective polarizing element and quarter-wave plate can be reduced, thereby facilitating optical path reflection, reducing the overall length of the optical system, and contributing to the miniaturization of the optical system.

[0048] In an exemplary embodiment, the optical system may further include a second spacer element disposed within the lens barrel, wherein the second spacer element is positioned on a second side surface of the second lens and at least partially contacts the second side surface of the second lens. Proper use of the spacer element can effectively mitigate stray light risks, reduce interference with image quality, and thereby improve the imaging quality of the optical system.

[0049] In other examples, the optical system may further include a first spacer element disposed within the lens barrel, wherein the first spacer element is positioned between a first lens and a second lens. In one example, the first spacer element may at least partially contact a second side surface of the first lens. In another example, the first spacer element may at least partially contact a first side end of the lens barrel. By controlling the relative position of the first spacer element within the lens barrel, the luminous flux of the optical system can be constrained, ensuring that the brightness of the optical system remains within a reasonable range.

[0050] In an exemplary embodiment, the optical system may further include an aperture stop, which may be disposed, for example, between the first side and the first lens. The user's eye can view the image projected by the display on the second side at the location of the aperture stop, that is, the image light on the display is finally projected to the user's eye after multiple refractions and reflections through the third lens, quarter-wave plate, second lens, reflective polarizing element and first lens.

[0051] In an exemplary embodiment, an image plane may be provided on the second side of the optical system, and a display may be provided on the image plane, for example. Image light from the display may sequentially pass through the third lens, the quarter-wave plate, the second lens, reach the reflective polarizing element, and then be reflected at the reflective polarizing element to form first reflected image light. The first reflected image light passes through the second lens, the quarter-wave plate, the third lens and reaches the partial reflection layer, and then is reflected at the partial reflection layer to form second reflected image light. The second reflected image light sequentially passes through the third lens, the quarter-wave plate, the second lens, the reflective polarizing element, the first lens to the aperture (i.e., the position where the user's eye views the image). In other examples, the order in which the image light and / or the first reflected image light and / or the second reflected image light pass through the second lens and the quarter-wave plate may be interchanged. The optical system provided in this application folds the required optical path in a manner that combines light reflection and refraction without affecting the projection quality, effectively shortening the body length of the optical system.

[0052] In an exemplary embodiment, the outer diameter of the second-side end face of the lens barrel is less than 60.0 mm, and the radius of curvature R6 of the second side face of the third lens and the outer diameter D0m of the second-side end face of the lens barrel may satisfy: R6 / D0m < -1.0. In an example, R6 / D0m < -1.3, or, -2.0 < R6 / D0m < -1.0. By controlling the above conditional expression, the second side face of the third lens can be limited to a convex surface and the convex surface shape is not overly protruding, effectively controlling the deflection angle of the light at the third lens, avoiding an overly large deflection angle of the light at the third lens, reducing the influence of the third lens on the imaging quality of the overall optical system, and at the same time, the outer shape size of the second-side end face of the lens barrel can be restricted and the outer diameter of the second-side end face of the lens barrel is less than 60.0 mm. While ensuring the processability of the lens barrel, the outer shape size of the second-side end face of the lens barrel is made as small as possible. Through the above design, it helps to reasonably control the mating relationship between the third lens and the second-side end face of the lens barrel, reduce the volume of the optical system, facilitate the miniaturization of the optical system, and at the same time reduce imaging quality problems such as poor resolution and clarity caused by unreasonable design at this position, reduce the risks such as dizziness and nausea of the user, relieve the burden of the user, and improve the user experience.

[0053] In an exemplary embodiment, the radius of curvature R5 of the first side surface of the third lens, the radius of curvature R6 of the second side surface of the third lens, the inner diameter d0m of the second side end surface of the lens barrel, and the outer diameter D0m of the second side end surface of the lens barrel may satisfy: 10.0 < (R5 - R6) / (D0m - d0m) < 50.0. In an example, 11.0 < (R5 - R6) / (D0m - d0m) < 40.0. By controlling the above conditional expression, the radii of curvature of the first side surface and the second side surface of the third lens can be restricted, so that the light can be deflected within a certain range when passing through the third lens, which is beneficial to reducing the sensitivity of the third lens and improving the assembly yield of the third lens; at the same time, the inner and outer diameters of the second side end surface of the lens barrel can be constrained within a reasonable range, improving the machinability of the lens barrel.

[0054] In an exemplary embodiment, the optical system further includes an image plane disposed on the second side. The distance TL from the first side surface of the first element group to the image plane on the optical axis and the total effective focal length f of the optical system may satisfy: TL / f < 1.0. In an example, 0.6 < TL / f < 0.95. By restricting the ratio of the distance from the first side surface of the first element group to the image plane on the optical axis to the total effective focal length of the optical system within a reasonable range, it is beneficial to improve the perspective effect of the optical system and the imaging quality of the optical system.

[0055] In an exemplary embodiment, the effective focal length f3 of the third element group and the interval EP02 between the first side end surface of the lens barrel and the second spacer element along the optical axis may satisfy: -20.0 < f3 / EP02 < -5.0. In an example, -15.0 < f3 / EP02 < -9.0. By controlling the above conditional expression, the ratio of the effective focal length of the third element group to the interval between the first side end surface of the lens barrel and the second spacer element along the optical axis can be restricted within a reasonable range, while ensuring that the optical power of the optical system is within a reasonable range, the amount of dispersion introduced by the reflective polarizing element and the quarter-wave plate is constrained, which is beneficial to correcting the chromatic aberration of the optical system.

[0056] In an exemplary embodiment, the radius of curvature R5 of the first side surface of the third lens, the radius of curvature R6 of the second side surface of the third lens, the outer diameter D2s of the first side surface of the second spacer element, and the outer diameter D2m of the second side surface of the second spacer element may satisfy: -5.0 < R5 / D2s + R6 / D2m < 0. In an example, -3.5 < R5 / D2s + R6 / D2m < -2.0. By controlling the above conditional expression, the radii of curvature of the first side surface and the second side surface of the third lens can be restricted, so that light can be deflected within a certain range when passing through the third lens, which is beneficial to reducing the sensitivity of the third lens and improving the assembly yield rate of the third lens; at the same time, the outer diameters of the first side surface and the second side surface of the second spacer element can be constrained within a reasonable range, improving the machinability of the second spacer element and being beneficial to the forming of the second spacer element.

[0057] In an exemplary embodiment, the optical system further includes an image plane disposed on the second side. The inner diameter d0m of the second side end surface of the lens barrel, the outer diameter D0m of the second side end surface of the lens barrel, the distance BL on the optical axis from the second side surface of the third lens to the image plane, and half of the maximum field angle Semi-FOV of the optical system satisfy: 1.0 < (D0m - d0m) / (BL × tan(Semi-FOV)) < 20.0. In an example, 1.2 < (D0m - d0m) / (BL × tan(Semi-FOV)) < 12.0. By controlling the above conditional expression, the luminous flux and the field angle of the optical system can be restricted, so that the brightness of the optical system is within a reasonable range, which is beneficial to improving the comfort of the device using the above optical system; at the same time, the inner and outer diameters of the second side end surface of the lens barrel can be restricted, so that the wall thickness of the second side end surface of the lens barrel is within a reasonable range, improving the machinability of the lens barrel and being beneficial to the forming of the lens barrel; in addition, the distance on the optical axis from the second side surface of the third lens to the image plane can be restricted, which is beneficial to constraining the optical power of the third element group within a reasonable range and improving the imaging quality of the optical system.

[0058] In an exemplary embodiment, the refractive index N1 of the first lens, the refractive index N2 of the second lens, the refractive index N of the reflective polarizing element R , the refractive index N of the quarter-wave plate Q , the central thickness CT1 of the first lens on the optical axis, the central thickness CT2 of the second lens on the optical axis, and the interval EP02 between the first side end surface of the lens barrel and the second spacer element along the optical axis may satisfy: 2.0 < (N1 + N2 + N R + N Q ) × (CT1 + CT2) / EP02 < 10.0. In an example, 6.0 < (N1 + N2 + N R + N Q)×(CT1+CT2) / EP02<9.0. By limiting the refractive index of the first lens, the second lens, the reflective polarizing element, and the quarter-wave plate, the optical power of the first lens, the second lens, the reflective polarizing element, and the quarter-wave plate can be controlled. Combined with the center thickness of the first lens and the second lens on the optical axis, the total effective focal length of the optical system can be controlled, thereby constraining the field of view of the optical system. At the same time, by limiting the spacing of the first side end face of the lens barrel and the second spacer element along the optical axis, the edge thickness of the first lens, the second lens, and the first spacer element can be controlled, which is beneficial to the shaping of the first lens, the second lens, and the first spacer element.

[0059] In an exemplary embodiment, the center thickness CT3 of the third lens on the optical axis, the length L of the lens barrel in the direction of the optical axis, and the distance EP02 between the first side end face of the lens barrel and the second spacer element along the optical axis can satisfy: 3.0 < (L - EP02) / CT3 < 8.0. In the example, 4.5 < (L - EP02) / CT3 < 6.0. By controlling the above conditional expressions, the center thickness of the third lens on the optical axis and the relative position of the second spacer element within the lens barrel can be adjusted, which helps to limit the effective focal length of the third element group within a certain range, so that the third element group produces positive spherical aberration, and the positive spherical aberration produced can be balanced with the negative spherical aberration produced by other element groups in the optical system, thereby ensuring that the optical system has good imaging quality.

[0060] In an exemplary embodiment, the axial distance SAG31 between the intersection of the first side surface of the third lens and the optical axis and the vertex of the effective half-aperture of the first side surface of the third lens, the air gap T23 between the second and third element groups on the optical axis, and the maximum thickness CP2 of the second spacer element can satisfy: -20.0 < (SAG31 + T23) / CP2 < 5.0. By limiting the axial distance between the intersection of the first side surface of the third lens and the optical axis and the vertex of the effective half-aperture of the first side surface of the third lens, it is helpful to constrain the optical power of the third element group. Combined with the air gap between the second and third element groups on the optical axis, the optical power of the optical system can be kept within a reasonable range. At the same time, limiting the maximum thickness of the second spacer element can improve the manufacturability of the second spacer element, which is beneficial to the molding of the second spacer element.

[0061] In an exemplary embodiment, the inner diameter d2m of the second side surface of the second spacer element, the maximum effective semi-aperture DT22 of the second side surface of the second lens, and the maximum effective semi-aperture DT31 of the first side surface of the third lens may satisfy: 0.5 < d2m / (DT22 + DT31) < 1.5. In an example, 0.8 < d2m / (DT22 + DT31) < 1.2. By controlling the above conditional expression, it is possible to limit the light flux at the positions of the second lens and the third lens of the optical system, so that the field angle of the optical system is within a reasonable range. At the same time, it is also possible to limit the outer shape dimensions of the second lens and the third lens, reduce the volume of the optical system, and facilitate the miniaturization of the optical system.

[0062] In an exemplary embodiment, the inner diameter d1m of the second side surface of the first spacer element and the effective focal length f2 of the second element group may satisfy: 0 < d1m / f2 < 5.0. In an example, 0.5 < d1m / f2 < 2.0. By controlling the above conditional expression, it is possible to limit the effective focal length of the second element group, so that the aberration of the optical system is within a reasonable range, which is beneficial to the imaging of the optical system; at the same time, it is also possible to limit the inner diameter of the second side surface of the first spacer element, improve the machinability of the first spacer element, and facilitate the shaping of the first spacer element.

[0063] In an exemplary embodiment, the maximum effective semi-aperture DT12 of the second side surface of the first lens, the maximum effective semi-aperture DT21 of the first side surface of the second lens, the inner diameter d1m of the second side surface of the first spacer element, and the outer diameter D1m of the second side surface of the first spacer element may satisfy: 1.0 < (DT12 + DT21) / (D1m - d1m) < 5.0. By controlling the above conditional expression, it is possible to limit the maximum effective semi-aperture of the second side surface of the first lens and the maximum effective semi-aperture of the first side surface of the second lens, so that the light transmission apertures of the first lens and the second lens are within a reasonable range, thereby ensuring that the contribution amounts of the coma of the first lens and the second lens are within a reasonable range and ensuring good imaging quality of the optical system; at the same time, it is also possible to limit the inner and outer diameters of the second side surface of the first spacer element, improve the machinability of the first spacer element, and facilitate the shaping of the first spacer element.

[0064] The optical system according to the above embodiments of this application can employ multiple lenses and at least one spacer element, such as the three lenses and one or two spacer elements described above. By rationally allocating the parameters of the lens barrel, reflective polarizing element, quarter-wave plate, each lens, and each spacer element, the overall length of the optical system can be reduced, stray light phenomena can be improved, and the manufacturability and imaging quality of the optical system can be enhanced. The optical system configured as described above features miniaturization, low stray light, compact structure, and good imaging quality, which can well meet the usage requirements of various portable electronic products in projection scenarios.

[0065] In the embodiments of this application, at least one of the mirror surfaces of the first to third lenses is an aspherical mirror surface. An aspherical lens is characterized by a continuously changing curvature from the lens center to the lens periphery. Unlike a spherical lens, which has a constant curvature from the lens center to the lens periphery, an aspherical lens has better curvature radius characteristics, offering advantages in improving distortion aberrations and astigmatism. By using an aspherical lens, aberrations occurring during imaging can be eliminated as much as possible, thereby improving image quality.

[0066] However, those skilled in the art should understand that, without departing from the technical solutions claimed in this application, the number of lenses and spacers constituting the optical system can be changed to obtain the various results and advantages described in this specification.

[0067] Specific embodiments of the optical system applicable to the above-described embodiments are further described below with reference to the accompanying drawings.

[0068] First Implementation Method

[0069] The following is for reference Figures 2 to 5C An optical system according to a first embodiment of this application is described. Figure 2 A schematic diagram of the structure of the optical system 110 according to Embodiment 1 of the first embodiment of this application is shown; Figure 3 A schematic diagram of the structure of the optical system 120 according to Embodiment 2 of the first embodiment of this application is shown; Figure 4 A schematic diagram of the structure of an optical system 130 according to Embodiment 3 of the first embodiment of this application is shown.

[0070] like Figures 2 to 4As shown, optical systems 110, 120, and 130 include a lens barrel P0 and a first element group, a second element group, and a third element group arranged sequentially along the optical axis from a first side to a second side within the lens barrel P0. The first element group includes a first lens E1 and a reflective polarizing element RP. The second element group includes a second lens E2 and a quarter-wave plate QWP. The third element group includes a third lens E3; in other examples, the third element group may also include a partial reflective layer BS (not shown). The optical system may also include a second spacer element P2; in other examples, the optical system may further include a first spacer element P1. In this embodiment, the first side refers to the human eye side, and the second side refers to the display side. The first side of each element (first lens E1, second lens E2, third lens E3, reflective polarizing element RP, and quarter-wave plate QWP) is referred to as the near-human eye side, and the second side is referred to as the near-display side.

[0071] The first lens E1 has two planar surfaces: the eye-side S1 and the display-side S2. The second lens E2 has positive optical power; its eye-side S4 and display-side S5 are convex. The third lens E3 has negative optical power; its eye-side S7 is concave and its display-side S8 is convex. The reflective polarizing element RP has two surfaces: the eye-side and the display-side S3. Its eye-side surface can be attached to the display-side S2 of the first lens E1. The quarter-wave plate QWP has two surfaces: the eye-side and the display-side S6. Its eye-side surface can be attached to the display-side S5 of the second lens E2. The partial reflective layer BS can be attached to the display-side S8 of the third lens E3.

[0072] In this example, an image surface S9 may be provided on the second side of the optical system, and the image surface S9 may, for example, be a display. Image light from the display sequentially passes through the third lens E3, the quarter-wave plate QWP, the second lens E2, and reaches the reflective polarizing element RP, where it undergoes a first reflection. The light after the first reflection passes through the second lens E2, the quarter-wave plate QWP, the third lens E3, and reaches the partial reflective layer BS, where it undergoes a second reflection. The light after the second reflection sequentially passes through the third lens E3, the quarter-wave plate QWP, the second lens E2, the reflective polarizing element RP, the first lens E1, and is finally projected onto a target object (not shown) in space. For example, the light from this optical system, after two reflections, is finally projected into the user's eye.

[0073] Table 1 shows the basic parameters of the optical system of the first embodiment, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0074]

[0075]

[0076] Table 1

[0077] In this embodiment, the total effective focal length f of the optical system is 20.65 mm, the effective focal length f2 of the second element group is 19.92 mm, the effective focal length f3 of the third element group is -102.65 mm, the distance TL between the first side of the first lens and the image plane of the optical system on the optical axis is 15.94 mm, and the value of half of the maximum field of view (Semi-FOV) of the optical system is 35.0°.

[0078] In the first embodiment, the near-eye side S4 and near-display side S5 of the second lens E2, and the near-eye side S7 and near-display side S8 of the third lens E3 are both aspherical. The surface shape x of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0079]

[0080] Where x is the distance vector from the vertex of the aspherical surface at a height of h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 2 gives the higher-order coefficients A4, A6, A8, A1, A2, A3, A4, A5, S7, S8 that can be used for each aspherical mirror S4, S5, S7, S8 in the first embodiment. 10 A 12 A 14 A 16 A 20 A 22 and A 24 .

[0081] Face number A4 A6 A8 A10 A12 S4 -1.0569E-01 -9.6538E-02 5.2086E-02 1.6699E-02 -2.4703E-03 S5 5.5013E-01 -3.3369E-02 5.0349E-02 -2.2553E-02 -6.7106E-03 S7 2.1011E-01 8.9911E-02 -3.0933E-02 -7.2067E-03 -9.4479E-04 S8 2.1804E-01 2.3352E-02 -3.4194E-02 4.2531E-03 1.0758E-03 Face number A14 A16 A20 A22 A24 S4 -3.0280E-03 -3.5484E-03 -1.3760E-04 -7.9909E-06 -4.9484E-07 S5 -4.3760E-04 2.8014E-04 1.3314E-06 0.0000E+00 0.0000E+00 S7 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S8 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0082] Table 2

[0083] The optical systems 110, 120, and 130 in embodiments 1, 2, and 3 of the first embodiment differ in the structural dimensions of the included lens barrel P0 and spacer element. Table 3 lists some basic parameters of the lens barrel P0, spacer element, and lens in each embodiment of the first embodiment, such as DT12, DT21, DT22, DT31, SAG31, d1m, D1m, d2m, D2s, D2m, d0m, D0m, L, EP02, and CP2. The basic parameters listed in Table 3 are... Figure 1 The annotation method shown is used for measurement, and the units of the basic parameters listed in Table 3 are all millimeters (mm).

[0084]

[0085]

[0086] Table 3

[0087] Figure 5A The on-axis chromatic aberration curves of the optical systems 110, 120 and 130 of the first embodiment are shown, which represent the deflection of the focal point of light of different wavelengths after passing through the optical systems 110, 120 and 130. Figure 5B Astigmatism curves of the optical systems 110, 120, and 130 of the first embodiment are shown, representing the meridional and sagittal image plane curvatures corresponding to different field angles. Figure 5C The distortion curves of the optical systems 110, 120, and 130 of the first embodiment are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 5A to 5C It can be seen that the optical systems 110, 120 and 130 given in the first embodiment can achieve good imaging quality.

[0088] Second Implementation Method

[0089] The following is for reference Figures 6 to 9C An optical system according to a second embodiment of this application is described. Figure 6 A schematic diagram of the structure of the optical system 210 according to Embodiment 1 of the second embodiment of this application is shown; Figure 7 A schematic diagram of the structure of the optical system 220 according to Embodiment 2 of the second embodiment of this application is shown; Figure 8 A schematic diagram of the structure of an optical system 230 according to Embodiment 3 of the second embodiment of this application is shown.

[0090] like Figures 6 to 8 As shown, optical systems 210, 220, and 230 include a lens barrel P0 and a first element group, a second element group, and a third element group arranged sequentially along the optical axis from the first side to the second side within the lens barrel P0. The first element group includes a first lens E1 and a reflective polarizing element RP. The second element group includes a second lens E2 and a quarter-wave plate QWP. The third element group includes a third lens E3; in other examples, the third element group may also include a partial reflective layer BS (not shown). The optical system may also include a first spacer element P1 and a second spacer element P2. In this embodiment, the first side refers to the human eye side, and the second side refers to the display side. The first side of each element (first lens E1, second lens E2, third lens E3, reflective polarizing element RP, and quarter-wave plate QWP) is referred to as the near-human eye side, and the second side is referred to as the near-display side.

[0091] The first lens E1 has positive optical power, with its eye-side S1 being convex and its display-side S2 being planar. The second lens E2 has positive optical power, with its eye-side S5 being planar and its display-side S6 being convex. The third lens E3 has negative optical power, with its eye-side S7 being concave and its display-side S8 being convex. The reflective polarizing element RP has an eye-side and a display-side S3, and its eye-side can be attached to the display-side S2 of the first lens E1. The quarter-wave plate QWP has an eye-side S4 and a display-side, and its display-side can be attached to the eye-side S5 of the second lens E2. The partial reflective layer BS can be attached to the display-side S8 of the third lens E3.

[0092] In this example, an image surface S9 may be provided on the second side of the optical system, and the image surface S9 may, for example, be a display. Image light from the display sequentially passes through the third lens E3, the second lens E2, the quarter-wave plate QWP, and reaches the reflective polarizing element RP, where it undergoes a first reflection. The light after the first reflection passes through the quarter-wave plate QWP, the second lens E2, the third lens E3, and reaches the partial reflective layer BS, where it undergoes a second reflection. The light after the second reflection sequentially passes through the third lens E3, the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, the first lens E1, and is finally projected onto a target object (not shown) in space. For example, the light from this optical system after two reflections is finally projected into the user's eye.

[0093] Table 4 shows the basic parameters of the optical system in the second embodiment, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0094]

[0095] Table 4

[0096] In this embodiment, the total effective focal length f of the optical system is 19.16 mm, the effective focal length f1 of the first element group is 198.27 mm, the effective focal length f2 of the second element group is 18.83 mm, the effective focal length f3 of the third element group is -98.33 mm, the distance TL between the first side of the first lens and the image plane of the optical system on the optical axis is 16.42 mm, and the value of half of the maximum field of view (Semi-FOV) of the optical system is 35.0°.

[0097] In the second embodiment, the near-eye side S1 of the first lens E1, the near-display side S6 of the second lens E2, and the near-eye side S7 and near-display side S8 of the third lens E3 are all aspherical. Table 5 lists the higher-order coefficients A4, A6, A8, and A6 of each aspherical mirror S1, S6, S7, and S8 that can be used in the second embodiment. 10 A 12 A 14 A 16 and A 20 .

[0098] Face number A4 A6 A8 A10 A12 A14 A16 A20 S1 1.8841E-01 1.0304E-01 6.1197E-02 3.0031E-02 3.8576E-03 0.0000E+00 0.0000E+00 0.0000E+00 S6 7.4923E+00 1.1024E+00 2.6722E-02 -3.2536E-01 2.1616E-01 -6.1317E-02 -1.0252E-02 -1.0301E-03 S7 -1.8149E-02 -1.7984E-01 -6.4372E-02 -9.1437E-03 -9.2328E-04 0.0000E+00 0.0000E+00 0.0000E+00 S8 -3.3645E-01 7.0532E-03 -3.7067E-02 5.1223E-03 1.2630E-03 0.0000E+00 0.0000E+00 0.0000E+00

[0099] Table 5

[0100] The optical systems 210, 220, and 230 in embodiments 1, 2, and 3 of the second embodiment differ in the structural dimensions of the included lens barrel P0 and spacer element. Table 6 lists some basic parameters of the lens barrel P0, spacer element, and lens in each embodiment of the second embodiment, such as DT12, DT21, DT22, DT31, SAG31, d1m, D1m, d2m, D2s, D2m, d0m, D0m, L, EP02, and CP2. The basic parameters listed in Table 6 are... Figure 1 The annotation method shown is used for measurement, and the units of the basic parameters listed in Table 6 are all millimeters (mm).

[0101]

[0102]

[0103] Table 6

[0104] Figure 9A The on-axis chromatic aberration curves of the optical systems 210, 220 and 230 of the second embodiment are shown, which represent the deflection of the focal point of light of different wavelengths after passing through the optical systems 210, 220 and 230. Figure 9B Astigmatism curves of optical systems 210, 220, and 230 of the second embodiment are shown, representing the meridional and sagittal image plane curvatures corresponding to different field angles. Figure 9C The distortion curves of the optical systems 210, 220, and 230 of the second embodiment are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 9A to 9C It can be seen that the optical systems 210, 220 and 230 given in the second embodiment can achieve good imaging quality.

[0105] Third Implementation Method

[0106] The following is for reference Figures 10 to 13CAn optical system according to a third embodiment of this application is described. Figure 10 A schematic diagram of the structure of the optical system 310 according to Embodiment 1 of the third embodiment of this application is shown; Figure 11 A schematic diagram of the structure of the optical system 320 according to Embodiment 2 of the third embodiment of this application is shown; Figure 12 A schematic diagram of the structure of an optical system 330 according to Embodiment 3 of the third embodiment of this application is shown.

[0107] like Figures 10 to 12 As shown, optical systems 310, 320, and 330 include a lens barrel P0 and a first element group, a second element group, and a third element group arranged sequentially along the optical axis from the first side to the second side within the lens barrel P0. The first element group includes a first lens E1. The second element group includes a second lens E2, a reflective polarizing element RP, and a quarter-wave plate QWP. The third element group includes a third lens E3; in other examples, the third element group may also include a partial reflective layer BS (not shown). The optical system may also include a first spacer element P1 and a second spacer element P2. In this embodiment, the first side refers to the human eye side, and the second side refers to the display side. The first side of each element (first lens E1, second lens E2, third lens E3, reflective polarizing element RP, and quarter-wave plate QWP) is referred to as the near-human eye side, and the second side is referred to as the near-display side.

[0108] The first lens E1 has positive optical power, with its eye-side S1 being convex and its display-side S2 being concave. The second lens E2 has positive optical power, with its eye-side S5 being planar and its display-side S6 being convex. The third lens E3 has negative optical power, with its eye-side S7 being concave and its display-side S8 being convex. The reflective polarizing element RP has an eye-side S3 and a display-side, and the quarter-wave plate QWP has an eye-side S4 and a display-side. The display-side of the reflective polarizing element RP is attached to the eye-side S4 of the quarter-wave plate QWP, and the display-side of the quarter-wave plate QWP can be attached to the eye-side S5 of the second lens E2. A partial reflective layer BS can be attached to the display-side S8 of the third lens E3.

[0109] In this example, an image surface S9 may be provided on the second side of the optical system, and the image surface S9 may, for example, be a display. Image light from the display sequentially passes through the third lens E3, the second lens E2, the quarter-wave plate QWP, and reaches the reflective polarizing element RP, where it undergoes a first reflection. The light after the first reflection passes through the quarter-wave plate QWP, the second lens E2, the third lens E3, and reaches the partial reflective layer BS, where it undergoes a second reflection. The light after the second reflection sequentially passes through the third lens E3, the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, the first lens E1, and is finally projected onto a target object (not shown) in space. For example, the light from this optical system after two reflections is finally projected into the user's eye.

[0110] Table 7 shows the basic parameters of the optical system of the third embodiment, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0111]

[0112] Table 7

[0113] In this embodiment, the total effective focal length f of the optical system is 17.93 mm, the effective focal length f1 of the first element group is 112.03 mm, the effective focal length f2 of the second element group is 43.50 mm, the effective focal length f3 of the third element group is -96.26 mm, the distance TL between the first side of the first lens and the image plane of the optical system on the optical axis is 16.69 mm, and the value of half of the maximum field of view (Semi-FOV) of the optical system is 35.0°.

[0114] In the third embodiment, the near-eye side S1 and near-display side S2 of the first lens E1, the near-display side S6 of the second lens E2, and the near-eye side S7 and near-display side S8 of the third lens E3 are all aspherical. Table 8 shows the higher-order coefficients A4, A6, A8, and A6 of each aspherical mirror S1, S2, S6, S7, and S8 that can be used in the second embodiment. 10 A 12 A 14 A 16 and A 20 .

[0115] Face number A4 A6 A8 A10 A12 A14 A16 A20 S1 -9.2106E-02 6.3380E-02 9.8208E-02 5.6060E-02 6.9993E-03 0.0000E+00 0.0000E+00 0.0000E+00 S2 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S6 1.0388E+01 1.2049E+00 -3.6827E-01 -2.0137E-01 2.2039E-01 -3.5048E-02 -4.1628E-02 -6.7157E-04 S7 -9.4526E-02 -4.8801E-02 -1.6424E-02 5.6001E-04 -7.6752E-05 0.0000E+00 0.0000E+00 0.0000E+00 S8 -2.9897E-01 4.5156E-02 -3.1657E-02 3.6835E-03 9.9031E-04 0.0000E+00 0.0000E+00 0.0000E+00

[0116] Table 8

[0117] The optical systems 310, 320, and 330 in embodiments 1, 2, and 3 of the third embodiment differ in the structural dimensions of the included lens barrel P0 and spacer element. Table 9 lists some basic parameters of the lens barrel P0, spacer element, and lens in each embodiment of the third embodiment, such as DT12, DT21, DT22, DT31, SAG31, d1m, D1m, d2m, D2s, D2m, d0m, D0m, L, EP02, and CP2. The basic parameters listed in Table 9 are... Figure 1 The annotation method shown is used for measurement, and the units of the basic parameters listed in Table 9 are all millimeters (mm).

[0118]

[0119] Table 9

[0120] Figure 13A The on-axis chromatic aberration curves of the optical systems 310, 320 and 330 of the third embodiment are shown, which represent the deflection of the focal point of light of different wavelengths after passing through the optical systems 310, 320 and 330. Figure 13B Astigmatism curves of optical systems 310, 320, and 330 of the third embodiment are shown, representing the meridional and sagittal image plane curvatures corresponding to different field of view angles. Figure 13C The distortion curves of the optical systems 310, 320, and 330 of the third embodiment are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 13A to 13C It can be seen that the optical systems 310, 320 and 330 given in the third embodiment can achieve good imaging quality.

[0121] In summary, Table 10 shows the values ​​of the conditional expressions for each embodiment in the first to third embodiments.

[0122] Conditional / Example 1-1 1-2 1-3 2-1 2-2 2-3 3-1 3-2 3-3 R6 / D0m -1.60 -1.72 -1.73 -1.58 -1.59 -1.68 -1.48 -1.53 -1.61 (R5-R6) / (D0m-d0m) 16.84 21.18 25.58 25.56 11.33 38.68 23.71 23.71 26.73 TL / f 0.77 0.77 0.77 0.86 0.86 0.86 0.93 0.93 0.93 d1m / f2 / / 1.81 1.79 1.94 1.92 0.69 0.71 0.70 (DT12+DT21) / (D1m-d1m) / / 4.11 2.64 3.94 4.90 2.00 2.49 2.81 f3 / EP02 -13.82 -13.29 -14.28 -9.21 -9.86 -11.08 -10.34 -12.09 -12.09 R5 / D2s+R6 / D2m -2.55 -2.70 -2.78 -2.49 -2.46 -2.66 -2.35 -2.50 -2.62 (D0m-d0m) / (BL×tan(Semi-FOV)) 1.95 1.55 1.28 5.27 11.89 3.48 2.56 2.56 2.27 <![CDATA[(N1+N2+N R +N Q )×(CT1+CT2) / EP02]]> 6.67 6.41 6.89 7.13 7.63 8.57 7.52 8.79 8.79 (L-EP02) / CT3 4.98 5.18 4.87 5.10 5.10 5.43 5.14 5.77 5.57 (SAG31+T23) / CP2 2.34 4.67 0.43 -16.47 -8.23 -1.14 -12.41 -0.74 -0.84 d2m / (DT22+DT31) 1.05 1.00 1.11 1.01 1.02 1.09 0.99 1.08 1.08

[0123] Table 10

[0124] This application also provides an optical device, which can be a standalone projection device such as a projector, or a projection module integrated into a mobile electronic device such as VR / AR. The optical device is equipped with the optical system described above.

[0125] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An optical system, characterized in that, The system includes a lens barrel and a first element group, a second element group, and a third element group arranged sequentially along the optical axis from a first side to a second side within the lens barrel. The first element group includes a first lens, the second element group includes a second lens with positive optical power, and the third element group includes a third lens with negative optical power. The second side of the second lens is convex, and the first side of the third lens is concave and the second side is convex. The optical system contains three lenses. The optical system further includes a reflective polarizing element, a quarter-wave plate, a partial reflective layer, and an image surface. The reflective polarizing element is located on the second side of the first lens or the first side of the second lens. The quarter-wave plate is located on the first side or the second side of the second lens. The partial reflective layer is located on the second side of the third lens. The image surface is located on the side of the third element group away from the second element group. The optical system further includes a first spacer element disposed between the first lens and the second lens, and a second spacer element disposed on the second side of the second lens and in contact with the second side of the second lens; The outer diameter of the second side end face of the lens barrel is less than 60.0 mm, and the radius of curvature R6 of the second side face of the third lens and the outer diameter D0m of the second side end face of the lens barrel satisfy: -1.73≤R6 / D0m≤-1.48; The effective focal length f3 of the third element group and the spacing EP02 of the first side end face of the lens barrel and the second spacer element along the optical axis satisfy: -14.28≤f3 / EP02≤-9.21; The inner diameter d1m of the second side of the first spacer element and the effective focal length f2 of the second element group satisfy: 0.69≤d1m / f2≤1.

94.

2. The optical system according to claim 1, characterized in that, The first or second side surface of at least one of the first lens, the second lens, and the third lens is configured as a plane.

3. The optical system according to claim 1, characterized in that, The radius of curvature R5 of the first side surface of the third lens, the radius of curvature R6 of the second side surface of the third lens, the inner diameter d0m of the second side end face of the lens barrel and the outer diameter D0m of the second side end face of the lens barrel satisfy: 11.33≤(R5-R6) / (D0m-d0m)≤38.

68.

4. The optical system according to claim 1, characterized in that, The distance TL from the first side of the first element group to the image plane on the optical axis satisfies the following condition: 0.77≤TL / f<0.

95.

5. The optical system according to any one of claims 1 to 4, characterized in that, The radius of curvature R5 of the first side of the third lens, the radius of curvature R6 of the second side of the third lens, the outer diameter D2s of the first side of the second spacer element, and the outer diameter D2m of the second side of the second spacer element satisfy: -2.78≤R5 / D2s+R6 / D2m≤-2.

35.

6. The optical system according to any one of claims 1 to 4, characterized in that, The inner diameter d0m of the second side end face of the lens barrel, the outer diameter D0m of the second side end face of the lens barrel, and the distance BL from the second side face of the third lens to the image surface on the optical axis satisfy the following condition: 1.28≤(D0m-d0m) / (BL×tan(Semi-FOV))≤11.

89.

7. The optical system according to any one of claims 1 to 4, characterized in that, The refractive index N1 of the first lens, the refractive index N2 of the second lens, and the refractive index N of the reflective polarizing element. R The refractive index N of the quarter-wave plate Q The center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, and the spacing EP02 of the first side end face of the lens barrel and the second spacer element along the optical axis satisfy: 6.41≤(N1+N2+N R +N Q )×(CT1+CT2) / EP02≤8.

79.

8. The optical system according to any one of claims 1 to 4, characterized in that, The center thickness CT3 of the third lens on the optical axis, the length L of the lens barrel in the direction of the optical axis, and the spacing EP02 of the first side end face of the lens barrel and the second spacer element along the optical axis satisfy: 4.87≤(L-EP02) / CT3≤5.

77.

9. The optical system according to any one of claims 1 to 4, characterized in that, The axial distance SAG31 between the intersection of the first side surface of the third lens and the optical axis and the effective half-aperture vertex of the first side surface of the third lens, the air gap T23 between the second element group and the third element group on the optical axis and the maximum thickness CP2 of the second spacer element satisfy: -16.47≤(SAG31+T23) / CP2≤4.

67.

10. The optical system according to any one of claims 1 to 4, characterized in that, The inner diameter d2m of the second side of the second spacer element, the maximum effective half-aperture DT22 of the second side of the second lens, and the maximum effective half-aperture DT31 of the first side of the third lens satisfy: 0.99≤d2m / (DT22+DT31)≤1.

11.

11. The optical system according to any one of claims 1 to 4, characterized in that, The maximum effective half-aperture DT12 of the second side of the first lens, the maximum effective half-aperture DT21 of the first side of the second lens, the inner diameter d1m of the second side of the first spacer element and the outer diameter D1m of the second side of the first spacer element satisfy: 2.00≤(DT12+DT21) / (D1m-d1m)≤4.90.

Images