Optical system

Abstract

The present application discloses an optical system, which includes a lens barrel and a lens group, a reflective assembly, and a spacer group disposed within the lens barrel, wherein the lens group includes a first lens, a second lens, and a third lens arranged in sequence from a first side to a second side along an optical axis; the reflective assembly includes a reflective polarizing element, a quarter-wave plate, and a partially reflective layer; the spacer group includes a second spacer disposed between the second lens and the third lens and in contact with a second side surface of the second lens; wherein a curvature radius R4 of the second side surface of the second lens, a center thickness CT2 of the second lens on the optical axis, an outer diameter D2m of the second side surface of the second spacer, and a maximum thickness CP2 of the second spacer satisfy the following: 0.5<|R4×CT2| / (D2m×CP2)<60.0.

Description

Technical Field

[0001] The present application relates to the field of optical devices, and in particular to a three-piece optical system. Background Art

[0002] With the advent of the "metaverse," users are increasingly finding entertainment options. Human-computer interaction technologies like virtual reality (VR) and augmented reality (AR) are gaining popularity. The optical systems used in VR / AR devices typically use aspherical or Fresnel lenses, which have long body lengths. This can cause the user's center of gravity to shift forward, severely impacting the user experience.

[0003] To reduce the length of the optical system, a two-piece folding system was designed. This folds the optical path to compress the system, reducing its length to half that of a conventional optical system. This shifts the user's center of gravity backward, enhancing the user experience. However, the two-piece folding system produces blurry, low-quality images of the external field of view. Summary of the Invention

[0004] The present 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.

[0005] One aspect of the present application provides an optical system, which includes a lens barrel and a lens group, a reflective assembly and a spacer group disposed in the lens barrel, wherein the lens group includes a first lens, a second lens and a third lens arranged in sequence from a first side to a second side along an optical axis; the reflective assembly includes a reflective polarizing element, a quarter-wave plate and a partially reflective layer; the spacer group includes a second spacer disposed between the second lens and the third lens and in contact with a second side surface of the second lens; wherein a curvature radius R4 of the second side surface of the second lens, a center thickness CT2 of the second lens on the optical axis, an outer diameter D2m of the second side surface of the second spacer and a maximum thickness CP2 of the second spacer satisfy the following conditions: 0.5<|R4×CT2| / (D2m×CP2)<60.0.

[0006] According to an exemplary embodiment of the present application, the reflective polarizing element is disposed between the first side and the second lens.

[0007] According to an exemplary embodiment of the present application, the partial reflective layer is disposed between the second lens and the third lens or between the third lens and the second side.

[0008] According to an exemplary embodiment of the present application, the first side surface of the first lens is configured to be one of a convex surface, a concave surface, or a flat surface at the paraxial region, and the second side surface of the first lens is configured to be a convex surface or a flat surface at the paraxial region.

[0009] According to an exemplary embodiment of the present application, the effective focal length f1 of the first lens and the total effective focal length f of the optical system satisfy: 4.0 < f1 / f < 30.0, the effective focal length f2 of the second lens and the total effective focal length f of the optical system satisfy: -57.0 < f2 / f < 14.0, and the effective focal length f3 of the third lens and the total effective focal length f of the optical system satisfy: 6.0 < f3 / f < 29.0.

[0010] According to an exemplary embodiment of the present application, the total effective focal length f of the optical system, half of the maximum field angle of the optical system Semi-FOV, the inner diameter d0s of the first side end surface of the lens barrel, and the inner diameter d0m of the second side end surface of the lens barrel satisfy: 0.2 < TAN(Semi-FOV)×(d0m - d0s) / f < 1.0.

[0011] According to an exemplary embodiment of the present application, the spacer group further includes a first spacer disposed between the first lens and the second lens and in contact with the second side surface of the first lens. The effective focal length f1 of the first lens, the outer diameter D1s of the first side surface of the first spacer, and the outer diameter D1m of the second side surface of the first spacer satisfy: 0.5 < f1 / (D1s + D1m) < 4.5.

[0012] According to an exemplary embodiment of the present application, the spacer group further includes a first spacer disposed between the first lens and the second lens and in contact with the second side surface of the first lens. Among them, the total effective focal length f of the optical system, the inner diameter d1s of the first side surface of the first spacer, and the inner diameter d1m of the second side surface of the first spacer satisfy: 5.0 < (d1s + d1m) / f < 7.0.

[0013] According to an exemplary embodiment of the present application, the spacer group further includes a first spacer disposed between the first lens and the second lens and in contact with the second side surface of the first lens. Among them, the interval EP01 between the first side end surface of the lens barrel and the first spacer along the optical axis, the maximum thickness CP1 of the first spacer, the central thickness CT1 of the first lens on the optical axis, the air interval T12 between the first lens and the second lens on the optical axis, and the central thickness d of the reflective polarizing element on the optical axis RP satisfy: 0.5 < (EP01 + CP1) / (CT + T12 + d RP ) < 2.0.

[0014] According to an exemplary embodiment of the present application, the spacer group also includes a first spacer placed between the first lens and the second lens and in contact with the second side surface of the first lens, wherein the effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the outer diameter D1m of the second side surface of the first spacer, and the outer diameter D2s of the first side surface of the second spacer satisfy: 3.0<|f1+f2| / (D1m+D2s)<10.0.

[0015] According to an exemplary embodiment of the present application, the curvature radius R3 of the first side surface of the second lens, the air gap T12 between the first lens and the second lens on the optical axis, the inner diameter d2s of the first side surface of the second spacer and the maximum thickness CP2 of the second spacer satisfy: 0<|R3×T12| / (d2s×CP2)<32.0.

[0016] According to an exemplary embodiment of the present application, the spacer group also includes a first spacer placed between the first lens and the second lens and in contact with the second side surface of the first lens, wherein the effective focal length f2 of the second lens, the air gap T23 between the second lens and the third lens on the optical axis, the interval EP12 between the first spacer and the second spacer along the optical axis, and the on-axis distance SAG22 from the intersection of the second side surface of the second lens and the optical axis to the effective semi-aperture vertex of the second side surface of the second lens satisfy: 2.0<|f2×T23| / |EP12×SAG22|<67.0.

[0017] According to an exemplary embodiment of the present application, the spacer set further includes a first spacer disposed between the first lens and the second lens and in contact with the second side surface of the first lens, wherein the effective focal length f3 of the third lens, the center thickness CT3 of the third lens on the optical axis, and the center thickness d of the quarter-wave plate on the optical axis are QWP , the interval EP12 between the first spacer and the second spacer along the optical axis and the maximum thickness CP2 of the second spacer satisfy: 10.0 <f3 / (d QWP +CT3+CP2+EP12)<80.0.

[0018] According to an exemplary embodiment of the present application, the curvature radius R5 of the first side surface of the third lens, the curvature radius R6 of the second side surface of the third lens, the outer diameter D0s of the first side end surface of the lens barrel, and the outer diameter D0m of the second side end surface of the lens barrel satisfy: -2.5<(R5+R6) / (D0s+D0m)<-1.0.

[0019] The optical system provided in the present application is configured as a three-piece folding system, which can effectively reduce the incident light with poor edge quality on the second side of the second lens and the useless light generated by reflection from the third lens by controlling the relationship between the curvature radius of the second side of the second lens, the center thickness of the second lens on the optical axis, the outer diameter of the second side of the second spacer and the maximum thickness of the second spacer, increase the uniformity of the all-directional distribution of light on the projection surface of the first side, and at the same time constrain the field curvature of the optical system within a reasonable range, so that the optical system obtains more light input, ensures that the external field imaging of the optical system is clear, and improves the imaging quality of the optical system. In addition, the shape of the second spacer can also be controlled to improve the machinability of the second spacer. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Other features, objects and advantages of the present application will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0021] Figure 1 shows a parameter diagram of an optical system according to the present application;

[0022] Figure 2 shows a schematic structural diagram of an optical system according to the present application;

[0023] Figure 3 1. A schematic diagram of an optical path of an optical system according to a first embodiment of the present application is shown;

[0024] Figure 4 1 shows a schematic structural diagram of an optical system according to Example 1 of the first embodiment of the present application;

[0025] Figure 5 1 shows a schematic structural diagram of an optical system according to Example 2 of the first embodiment of the present application;

[0026] Figures 6A to 6C axial chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to the first embodiment of the present application are respectively shown;

[0027] Figure 7 1. A schematic diagram of an optical path of an optical system according to a second embodiment of the present application is shown;

[0028] Figure 8 1 shows a schematic structural diagram of an optical system according to Example 1 of the second embodiment of the present application;

[0029] Figure 9 FIG2 shows a schematic structural diagram of an optical system according to Example 2 of the second embodiment of the present application;

[0030] Figures 10A to 10Caxial chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to the second embodiment of the present application are respectively shown;

[0031] Figure 11 FIG2 shows a light path schematic diagram of an optical system according to a third embodiment of the present application;

[0032] Figure 12 1 shows a schematic structural diagram of an optical system according to Example 1 of the third embodiment of the present application;

[0033] Figure 13 FIG2 shows a schematic structural diagram of an optical system according to Example 2 of the third embodiment of the present application;

[0034] 14A to 14C axial chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to the third embodiment of the present application are respectively shown;

[0035] Figure 15 FIG4 shows a light path schematic diagram of an optical system according to a fourth embodiment of the present application;

[0036] Figure 16 1 shows a schematic structural diagram of an optical system according to Example 1 of the fourth embodiment of the present application;

[0037] Figure 17 shows a schematic structural diagram of an optical system according to Example 2 of the fourth embodiment of the present application; and

[0038] 18A to 18C The axial chromatic aberration curve, the astigmatism curve, and the distortion curve of the optical system according to the fourth embodiment of the present application are respectively shown. DETAILED DESCRIPTION

[0039] In order to better understand the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely 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.

[0040] It should be noted that in this specification, the terms "first," "second," "third," etc., are used solely to distinguish one feature from another and do not limit the features. Thus, the first lens discussed below could also be referred to as the second lens or the third lens without departing from the teachings of this application.

[0041] In the drawings, the thickness, size, and shape of the lenses are slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical and aspherical surfaces shown in the drawings are provided by way of example. That is, the shapes of the spherical and aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0042] In this document, the paraxial region refers to the region near the optical axis. If a lens surface is convex and the position of the convex surface is undefined, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the position of the concave surface is undefined, 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 receiving side) is called the first side surface of the lens, and the surface of each lens closest to the second side (e.g., the transmitting side) is called the second side surface of the lens.

[0043] It should also be understood that the terms "comprise," "including," "having," "include," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when describing embodiments of the present application, the term "may" is used to mean "one or more embodiments of the present application." Furthermore, the term "exemplary" is intended to refer to an example or illustration.

[0044] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and will not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.

[0045] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this 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.

[0046] The features, principles and other aspects of the present application are described in detail below.

[0047] like Figures 3 to 5 、 Figures 7 to 9 、 Figures 11 to 13 as well as Figures 15 to 17 As shown, an optical system according to an exemplary embodiment of the present application may include a lens barrel and a lens group disposed within the lens barrel. The lens group may include a first lens, a second lens, and a third lens arranged in sequence from a first side to a second side along an optical axis. Among the first lens to the third lens, any two adjacent lenses may have an air gap between them.

[0048] In an exemplary embodiment, the optical system may further include a reflective assembly disposed within the lens barrel. The reflective assembly may include a reflective polarizing element, a quarter-wave plate, and a partially reflective layer, wherein the partially reflective layer has a semi-transmissive and semi-reflective effect on light. The reflective assembly reflects light entering the optical system, but this does not necessarily mean that every element in the reflective assembly reflects light.

[0049] In an exemplary embodiment, the first side may be, for example, the receiving unit side, and the second side may be, for example, the transmitting unit side. Accordingly, the first side of each element (the first lens, the second lens, the third lens, the reflective polarizer, the quarter-wave plate, and the partially reflective layer) may be referred to as the side proximal to the receiving unit, and the second side may be referred to as the side proximal to the transmitting unit. The receiving unit may be, for example, a human eye, and the transmitting unit may be, for example, a display screen.

[0050] In an exemplary embodiment, the reflective polarizing element can be arranged between the first side and the second lens. As an example, the reflective polarizing element can be arranged between the first side and the first lens or between the first lens and the second lens. As an example, the reflective polarizing element can be attached to the first side surface or the second side surface of the first lens. By setting the reflective polarizing element in the above-mentioned position, it can be ensured that the light must pass through the second lens and the third lens before passing through the reflective polarizing element for refracting, effectively extending the optical path and folding the optical path. While ensuring that the optical system has the same imaging magnification, the main body length of the optical system is effectively reduced, thereby improving the user experience.

[0051] In exemplary embodiments, a partially reflective layer can be positioned between the second lens and the third lens, or between the third lens and the second side. For example, the partially reflective layer can be attached to the first or second side of the third lens. Placing the partially reflective layer in these locations ensures that light reflected by the reflective polarizing element must pass through the second lens, or between the second and third lenses, before being reflected again. This effectively extends the optical path and folds the optical path. While maintaining the same imaging magnification, the optical system's overall length can be reduced, enhancing the user experience.

[0052] In an exemplary embodiment, the quarter-wave plate may be disposed between the second lens and the third lens. As an example, the quarter-wave plate may be attached to a first side surface of the third lens.

[0053] In an exemplary embodiment, the optical system may further include a spacer assembly disposed within the lens barrel. The spacer assembly may include a first spacer, wherein the first spacer is disposed between the first lens and the second lens and at least partially contacts the second side surface of the first lens. Proper use of spacers can effectively mitigate stray light risks, reduce interference with image quality, and thereby improve the imaging quality of the optical system.

[0054] In other examples, the spacer assembly may further include a second spacer, wherein the second spacer may be disposed between the second lens and the third lens and at least partially contact the second side surface of the second lens. The first spacer and the second spacer may be independent spacers. Alternatively, the first spacer and the second spacer may be spanning spacers, i.e., the sides of the first spacer and the second spacer that are adjacent to the lens barrel may be connected together.

[0055] In other examples, a first auxiliary spacer at least partially in contact with the second side of the first spacer may be included between the first spacer and the second lens. A second auxiliary spacer at least partially in contact with the second side of the second spacer may be included between the second spacer and the third lens.

[0056] In an exemplary embodiment, the optical system may further include an aperture, which may be disposed between the first side and the first lens. The receiving portion on the first side can view the image projected by the emitting portion on the second side at the location of the aperture. Specifically, the image light from the emitting portion is refracted and reflected multiple times by the third lens, the quarter-wave plate, the second lens, the reflective polarizer, and the first lens before being projected onto the receiving portion.

[0057] In an exemplary embodiment, a light source may be provided on the emitting portion. Image light from the light source may be emitted from the emitting portion and sequentially pass through the third lens, the quarter-wave plate, and the second lens to reach the reflective polarizing element, and then be reflected at the reflective polarizing element to form a first reflection of the image light. The first reflection of the image light passes through the second lens, the quarter-wave plate, and reaches the partially reflective layer on the second side surface of the third lens, and then is reflected at the partially reflective layer to form a second reflection of the image light. The second reflection of the 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 receiving portion views the image). In other examples, the first reflection of the image light may also pass through the second lens and reach the partially reflective layer on the side of the quarter-wave plate near the emitting portion, and then be reflected at the partially reflective layer to form a second reflection of the image light, and the second reflection of the image light does not need to pass through the third lens. In other examples, the image light from the light source needs to pass through the first lens and be reflected by the reflective polarizing element on the first side surface of the first lens to form the first reflection of the image light, and the first reflection of the image light needs to pass through the first lens to be reflected by the partially reflective layer to form the second reflection of the image light. The optical system provided in the present application folds the required optical path without affecting the projection quality by combining light reflection and refraction, thereby effectively shortening the main body length of the optical system.

[0058] In an exemplary embodiment, the first side surface of the first lens is configured to be one of a convex surface, a concave surface, or a flat surface at the paraxial region, and the second side surface of the first lens is configured to be a convex surface or a flat surface at the paraxial region. By setting the first side surface and the second side surface of the first lens in the above forms, the direction of light can be effectively controlled, which is more conducive to light convergence. Moreover, when the first side surface or the second side surface of the first lens is set as a flat surface, it is beneficial for the attachment of the reflective polarizing element.

[0059] In an exemplary embodiment, the radius of curvature R4 of the second side surface of the second lens, the central thickness CT2 of the second lens on the optical axis, the outer diameter D2m of the second side surface of the second spacer, and the maximum thickness CP2 of the second spacer may satisfy: 0.5 < |R4 × CT2| / (D2m × CP2) < 60.0. By controlling the above conditional formula, the incident light with poor edge quality on the second side surface of the second lens and the useless light generated by the reflection of the third lens can be effectively reduced, the uniformity of the light distribution in the projection plane on the first side can be increased, and at the same time, the field curvature of the optical system can be constrained within a reasonable range, enabling the optical system to obtain more light input, ensuring the clarity of the imaging picture of the outer field of view of the optical system, and improving the imaging quality of the optical system. In addition, the shape of the second spacer can be controlled, and the machinability of the second spacer can be improved.

[0060] In an exemplary embodiment, the effective focal length f1 of the first lens and the total effective focal length f of the optical system may satisfy: 4.0 < f1 / f < 30.0, the effective focal length f2 of the second lens and the total effective focal length f of the optical system may satisfy: -57.0 < f2 / f < 14.0, and the effective focal length f3 of the third lens and the total effective focal length f of the optical system may satisfy: 6.0 < f3 / f < 29.0. By constraining the ratios of the effective focal lengths of the first lens, the second lens, and the third lens to the total effective focal length of the optical system within reasonable ranges respectively, while enabling the optical system to meet the characteristics of a large field of view, the optical power of each lens can be reasonably distributed. On the premise of meeting the total effective focal length of the optical system, the aberration of the optical system can be effectively corrected, and the imaging quality of the optical system can be improved.

[0061] In an exemplary embodiment, the total effective focal length f of the optical system, half of the maximum field of view angle Semi - FOV of the optical system, the inner diameter d0s of the first side end face of the lens barrel, and the inner diameter d0m of the second side end face of the lens barrel may satisfy: 0.2 < TAN(Semi - FOV) × (d0m - d0s) / f < 1.0. By controlling the above conditional formula, the field of view angle of the optical system can be effectively constrained, enabling the optical system to meet the characteristics of a large field of view. At the same time, the inner diameter of the second side end face of the lens barrel can be restricted within a reasonable range, ensuring that the lens barrel can block the excessive light from entering the interior of the lens barrel, and effectively avoiding stray light.

[0062] In an exemplary embodiment, the effective focal length f1 of the first lens, the outer diameter D1s of the first side surface of the first spacer, and the outer diameter D1m of the second side surface of the first spacer may satisfy: 0.5 < f1 / (D1s + D1m) < 4.5. By controlling the above conditional expression, the first lens can be made a positive lens, which is beneficial to light convergence. At the same time, the outer diameters of the first side surface and the second side surface of the first spacer can be constrained within a reasonable range, ensuring stable abutment of the first spacer with the first lens and the second lens respectively, and improving the assembly stability of the optical system.

[0063] In an exemplary embodiment, the total effective focal length f of the optical system, the inner diameter d1s of the first side surface of the first spacer, and the inner diameter d1m of the second side surface of the first spacer may satisfy: 5.0 < (d1s + d1m) / f < 7.0. By controlling the above conditional expression, the total effective focal length of the optical system can be limited within a reasonable range, which is beneficial to limiting the body length of the optical system and improving the user experience. At the same time, the inner diameters of the first side surface and the second side surface of the first spacer can be constrained within a reasonable range, effectively reducing stray light in the optical system, ensuring stable abutment of the first spacer with the first lens and the second lens respectively, and improving the assembly stability of the optical system.

[0064] In an exemplary embodiment, the interval EP01 along the optical axis between the first side end face of the lens barrel and the first spacer, the maximum thickness CP1 of the first spacer, the central thickness CT1 of the first lens on the optical axis, the air interval T12 between the first lens and the second lens on the optical axis, and the central thickness d of the reflective polarizing element on the optical axis RP may satisfy: 0.5 < (EP01 + CP1) / (CT1 + T12 + d RP ) < 2.0. By controlling the above conditional expression, the central thickness of the first lens on the optical axis and the air interval between the first lens and the second lens on the optical axis can be reasonably allocated, thereby constraining the field curvature of the optical system within a reasonable range, ensuring good imaging performance of the optical system. At the same time, the central thickness of the reflective polarizing element on the optical axis can be limited within a reasonable range, reducing the haze of the reflective polarizing element, improving the transmittance and processability of the reflective polarizing element, and further ensuring good imaging performance of the optical system.

[0065] In an exemplary embodiment, the effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the outer diameter D1m of the second side surface of the first spacer, and the outer diameter D2s of the first side surface of the second spacer can satisfy the following equation: 3.0 < |f1+f2| / (D1m+D2s) < 10.0. By controlling this conditional expression, the optical power of the optical system can be limited, thereby facilitating adjustment of the beam focus position and shortening the main length of the optical system. Furthermore, the outer diameter of the second lens and the inner diameter of the corresponding portion of the lens barrel can be constrained within a reasonable range, improving the manufacturability of the second lens and the lens barrel.

[0066] In an exemplary embodiment, the radius of curvature R3 of the first side surface of the second lens, the air gap T12 between the first lens and the second lens on the optical axis, the inner diameter d2s of the first side surface of the second spacer, and the maximum thickness CP2 of the second spacer can satisfy the following: 0 < |R3×T12| / (d2s×CP2) < 32.0. By controlling the above conditional expression, the inner diameter of the first side surface of the second spacer and the maximum thickness of the second spacer can be limited to a reasonable range, thereby constraining the structural shape of the second spacer. While meeting the assembly requirements of the optical system, the machinability of the second spacer is improved. At the same time, the radius of curvature of the first side surface of the second lens and the air gap between the first lens and the second lens on the optical axis can be limited to a reasonable range. While ensuring the structural compactness of the optical system, it is beneficial to correct the off-axis aberrations of the optical system and improve the overall image quality of the optical system.

[0067] In an exemplary embodiment, the effective focal length f2 of the second lens, the air gap T23 on the optical axis between the second lens and the third lens, and the on-axis distance SAG22 from the intersection of the interval EP12 between the first and second spacers along the optical axis and the second side surface of the second lens and the optical axis to the effective semi-aperture vertex of the second side surface of the second lens can satisfy the following: 2.0 < |f2 × T23| / |EP12 × SAG22| < 67.0. By controlling the above conditional expressions, the effective focal length, edge thickness, and sag height of the second side surface of the second lens can be limited, thereby effectively constraining the shape of the second lens, reducing the difficulty of manufacturing the second lens, controlling the direction of light, optimizing the ghost images produced by the second lens, and improving the imaging quality of the optical system. Furthermore, the air gap between the second and third lenses on the optical axis can be limited to a reasonable range, which facilitates correction of off-axis aberrations of the optical system and ensures good imaging performance.

[0068] In an exemplary embodiment, the effective focal length f3 of the third lens, the center thickness CT3 of the third lens on the optical axis, and the center thickness d of the quarter-wave plate on the optical axis are QWPThe interval EP12 between the first spacer and the second spacer along the optical axis and the maximum thickness CP2 of the second spacer can satisfy: 10.0 <f3 / (d QWP +CT3+CP2+EP12)<80.0. By controlling the above conditional expression, the center thickness of the quarter-wave plate on the optical axis can be limited to a reasonable range, reducing the haze of the quarter-wave plate, improving the transmittance and machinability of the quarter-wave plate, thereby ensuring good imaging results for the optical system. At the same time, the center thickness of the third lens on the optical axis, the spacing between the first and second spacers along the optical axis, and the maximum thickness of the second spacer can be reasonably allocated. This ensures that the machinability of the third lens, first spacer, and second spacer is met while ensuring that the main length of the optical system meets the requirements of miniaturized equipment.

[0069] 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 D0s of the first side end surface of the lens barrel, and the outer diameter D0m of the second side end surface of the lens barrel can satisfy the following relationship: -2.5 < (R5 + R6) / (D0s + D0m) < -1.0. By controlling the above conditional expression, the optical power of the third lens can be limited, the deflection angle of the marginal light of the optical system can be reasonably constrained, the sensitivity of the optical system can be effectively reduced, and the image quality and relative illumination of the optical system can be improved. At the same time, the outer diameters of the first and second side end surfaces of the lens barrel can be limited to within a reasonable range, making the angular direction of the lens barrel appearance smoother and reducing the difficulty of lens barrel processing.

[0070] The optical system according to the above-described embodiment of the present application can utilize multiple lenses, a reflective assembly, and at least one spacer, such as the three lenses, reflective assembly, and two spacers described above. By rationally allocating the parameters of each lens, reflective assembly, and spacer, the main length of the optical system can be reduced, the stray light phenomenon of the optical system can be improved, and the workability, assembly stability, and imaging quality of the optical system can be improved. The optical system configured in this manner features miniaturization, good assembly stability, low stray light, a compact structure, and excellent imaging quality, and can well meet the usage requirements of various portable electronic products in projection scenarios.

[0071] In an embodiment of the present application, at least one of the mirror surfaces of each of the first through third lenses is an aspheric surface. Aspheric lenses are characterized by a continuously varying curvature from the center to the periphery. Unlike spherical lenses, which have a constant curvature from the center to the periphery, aspheric lenses have a better curvature radius characteristic, with the advantages of reducing distortion and astigmatism. The use of aspheric lenses can minimize aberrations that occur during imaging, thereby improving image quality.

[0072] However, those skilled in the art will appreciate that, without departing from the technical solution claimed in the present application, the number of lenses and spacers constituting the optical system may be changed to obtain the various results and advantages described in this specification.

[0073] Specific embodiments of the optical system applicable to the above-mentioned embodiments will be further described below with reference to the accompanying drawings.

[0074] First embodiment

[0075] The following reference Figures 3 to 6C An optical system according to a first embodiment of the present application is described. Figure 3 1. A schematic diagram of an optical path of an optical system according to a first embodiment of the present application is shown; Figure 4 1 shows a schematic structural diagram of an optical system 110 according to Example 1 of the first embodiment of the present application; Figure 5 FIG2 shows a schematic structural diagram of an optical system 120 according to Example 2 of the first embodiment of the present application.

[0076] like Figures 3 to 5 As shown, optical systems 110 and 120 each include a lens barrel P0, a lens assembly, a reflective assembly, and a spacer assembly disposed within the lens barrel P0. The lens assembly includes, from the first side to the second side, a first lens E1, a second lens E2, and a third lens E3. In this embodiment, the first side refers to the receiving portion side, and the second side refers to the transmitting portion side. An aperture STO may be disposed between the receiving portion and the first lens E1. The reflective assembly includes a reflective polarizer RP, a quarter-wave plate QWP, and a partially reflective layer BS. The reflective polarizer RP is disposed between the first lens E1 and the second lens E2, and the quarter-wave plate QWP is disposed between the second lens E2 and the third lens E3. The spacer assembly includes a first spacer P1 and a second spacer P2. In this embodiment, the first side of each element (the first lens E1, the second lens E2, the third lens E3, the reflective polarizer RP, the quarter-wave plate QWP, and the partially reflective layer BS) is referred to as the near-receiving portion side, and the second side is referred to as the near-transmitting portion side.

[0077] The first lens E1 has positive optical power, with its near-receiving side S1 being convex and its near-emitting side S2 being flat. The second lens E2 has positive optical power, with its near-receiving side S3 being convex and its near-emitting side S4 being convex. The third lens E3 has positive optical power, with its near-receiving side S5 being concave and its near-emitting side S6 being convex. A reflective polarizer RP can be attached to the near-emitting side S2 of the first lens E1. A quarter-wave plate QWP can be attached to the near-receiving side S5 of the third lens E3. A partially reflective layer BS can be attached to the near-emitting side S6 of the third lens E3.

[0078] In this example, the emitting unit may be provided with a light source. Image light from the emitting unit sequentially passes through the third lens E3, the quarter-wave plate QWP, and the second lens E2, reaching the reflective polarizer RP, where it undergoes a first reflection. The light that has undergone the first reflection passes through the second lens E2, the quarter-wave plate QWP, and reaches the partially reflective layer BS on the near-emitting side of the third lens E3, where it undergoes a second reflection. The light that has undergone the second reflection sequentially passes through the third lens E3, the quarter-wave plate QWP, the second lens E2, the reflective polarizer RP, and the first lens E1, ultimately projecting onto a receiving unit in space. For example, the light from this optical system, after being reflected twice, is ultimately projected into the user's eyes.

[0079] Table 1 shows the basic parameters of the optical system of the first embodiment, where the units of curvature radius and thickness / distance are all in millimeters (mm). Image light from the transmitting unit passes through each element in the order of sequence numbers 19 to 1 and is ultimately projected onto a receiving unit in space, such as the human eye.

[0080]

[0081]

[0082] Table 1

[0083] In this embodiment, the total effective focal length f of the optical system is 15.94 mm, the effective focal length f1 of the first lens is 473 mm, the effective focal length f2 of the second lens is 84.33 mm, the effective focal length f3 of the third lens is 325.02 mm, the half of the maximum field of view angle Semi-FOV of the optical system is 45.0°, and the on-axis distance SAG22 from the intersection of the second side surface of the second lens and the optical axis to the effective semi-aperture vertex of the second side surface of the second lens is -2.87 mm.

[0084] In the first embodiment, the near receiving portion side surface S1 of the first lens E1, the near receiving portion side surface S3 and the near emitting portion side surface S4 of the second lens E2, and the near receiving portion side surface S5 and the near emitting portion side surface S6 of the third lens E3 are all aspherical surfaces. The surface shape z of each aspherical lens can be defined by, but is not limited to, the following aspherical surface formula:

[0085]

[0086] Where z is the depth of the aspheric surface (the vertical distance between the point y away from the optical axis on the aspheric surface and the tangent plane tangent to the vertex on the optical axis of the aspheric surface); c is the curvature of the vertex of the aspheric surface; K is the conic coefficient, is the radial distance; u is r / r n ; r nis the normalized radius; a m is the mth order Q con Coefficient; Q m con is the mth order Q con Polynomial. Table 2 shows the cone coefficient K and the polynomial coefficients a0, a1, a2, and a3 of the aspherical mirror surfaces S1, S3-S6 that can be used in the first embodiment.

[0087] Face number K a0 a1 a2 a3 S1 0.0000 1.10E+00 -8.97E-01 2.06E-01 0.00E+00 S3 0.0000 -7.46E+00 1.21E+00 -1.37E-01 -6.09E-02 S4 0.0000 -2.34E+00 1.17E+00 -1.66E-01 0.00E+00 S5 0.0000 1.65E+00 4.67E-01 -6.10E-02 0.00E+00 S6 0.0000 4.85E-01 1.11E-01 1.00E-01 0.00E+00

[0088] Table 2

[0089] Figure 6A The axial chromatic aberration curves of the optical systems 110 and 120 of the first embodiment are shown, which indicate the deviation of the convergence point of light rays of different wavelengths after passing through the optical systems 110 and 120 . Figure 6B Astigmatism curves of the optical systems 110 and 120 according to the first embodiment are shown, which represent meridional field curvature and sagittal field curvature corresponding to different half field angles. Figure 6C The distortion curves of the optical systems 110 and 120 of the first embodiment are shown, which represent the distortion values ​​corresponding to different half-field angles. Figures 6A to 6C It can be seen that the optical systems 110 and 120 provided in the first embodiment can achieve good imaging quality.

[0090] Second embodiment

[0091] The following reference Figures 7 to 10C An optical system according to a second embodiment of the present application will be described. Figure 7 1. A schematic diagram of an optical path of an optical system according to a second embodiment of the present application is shown; Figure 8 1 shows a schematic structural diagram of an optical system 210 according to Example 1 of the second embodiment of the present application; Figure 9 FIG2 shows a schematic structural diagram of an optical system 220 according to Example 2 of the second embodiment of the present application.

[0092] like Figures 7 to 9As shown, optical systems 210 and 220 each include a lens barrel P0, a lens assembly, a reflective assembly, and a spacer assembly disposed within the lens barrel P0. The lens assembly includes, from the first side to the second side, a first lens E1, a second lens E2, and a third lens E3. In this embodiment, the first side refers to the receiving portion side, and the second side refers to the transmitting portion side. An aperture STO may be disposed between the receiving portion and the first lens E1. The reflective assembly includes a reflective polarizer RP, a quarter-wave plate QWP, and a partially reflective layer BS. The reflective polarizer RP is disposed between the first lens E1 and the second lens E2, and the quarter-wave plate QWP is disposed between the second lens E2 and the third lens E3. The spacer assembly includes a first spacer P1 and a second spacer P2. In this embodiment, the first side of each element (the first lens E1, the second lens E2, the third lens E3, the reflective polarizer RP, the quarter-wave plate QWP, and the partially reflective layer BS) is referred to as the near-receiving portion side, and the second side is referred to as the near-transmitting portion side.

[0093] The first lens E1 has positive optical power, with its near-receiving side S1 being convex and its near-emitting side S2 being flat. The second lens E2 has positive optical power, with its near-receiving side S3 being convex and its near-emitting side S4 being convex. The third lens E3 has positive optical power, with its near-receiving side S5 being concave and its near-emitting side S6 being convex. A reflective polarizer RP can be attached to the near-emitting side S2 of the first lens E1. A quarter-wave plate QWP and a partially reflecting layer BS can both be attached to the near-receiving side S5 of the third lens E3, with the partially reflecting layer BS being closer to the third lens E3 than the quarter-wave plate QWP.

[0094] In this example, the emitting unit may be provided with a light source. Image light from the emitting unit sequentially passes through the third lens E3, the quarter-wave plate QWP, and the second lens E2, reaching the reflective polarizer RP. It then undergoes a first reflection at the reflective polarizer RP. The first-reflected light then passes through the second lens E2 and reaches the partially reflective layer BS on the near-emitting side of the quarter-wave plate QWP. It then undergoes a second reflection at the partially reflective layer BS. The second-reflected light then sequentially passes through the quarter-wave plate QWP, the second lens E2, the reflective polarizer RP, and the first lens E1, ultimately projecting onto a receiving unit in space. For example, the light from this optical system, after two reflections, is ultimately projected into the user's eyes.

[0095] Table 3 shows the basic parameters of the optical system of the second embodiment, where the units of curvature radius and thickness / distance are all in millimeters (mm). Image light from the transmitting unit passes through each element in the order of sequence numbers 17 to 1 and is ultimately projected onto a receiving unit in space, such as the human eye.

[0096]

[0097]

[0098] Table 3

[0099] In this embodiment, the total effective focal length f of the optical system is 15.63 mm, the effective focal length f1 of the first lens is 370.34 mm, the effective focal length f2 of the second lens is 62.19 mm, the effective focal length f3 of the third lens is 448.13 mm, the value of Semi-FOV, which is half of the maximum field of view angle of the optical system, is 50.0°, and the value of the on-axis distance SAG22 from the intersection of the second side surface of the second lens and the optical axis to the effective semi-aperture vertex of the second side surface of the second lens is -4.87 mm.

[0100] In the second embodiment, the near-receiving side surface S1 of the first lens E1, the near-receiving side surface S3 and the near-emitting side surface S4 of the second lens E2, and the near-receiving side surface S5 and the near-emitting side surface S6 of the third lens E3 are all aspherical surfaces. Table 4 lists the conic coefficient K and the polynomial coefficients a0, a1, a2, and a3 of the aspherical mirror surfaces S1, S3-S6 that can be used in the second embodiment.

[0101] Face number K a0 a1 a2 a3 S1 0.0000 4.66E-01 -5.59E-02 -1.42E-03 0.00E+00 S3 0.0000 -3.96E-01 -7.15E-02 1.20E-02 0.00E+00 S4 0.0000 2.28E+00 -3.62E-01 8.30E-02 -4.95E-03 S5 0.0000 -3.91E-01 7.29E-02 -8.55E-03 5.69E-04 S6 0.0000 6.93E-01 -2.08E-01 3.15E-02 -1.34E-03

[0102] Table 4

[0103] Figure 10A The axial chromatic aberration curves of the optical systems 210 and 220 of the second embodiment are shown, which represent the deviation of the convergence point of light rays of different wavelengths after passing through the optical systems 210 and 220. Figure 10B Astigmatism curves of the optical systems 210 and 220 according to the second embodiment are shown, which represent meridional field curvature and sagittal field curvature corresponding to different half field angles. Figure 10C The distortion curves of the optical systems 210 and 220 of the second embodiment are shown, which represent the distortion values ​​corresponding to different half-field angles. Figures 10A to 10C It can be seen that the optical systems 210 and 220 provided in the second embodiment can achieve good imaging quality.

[0104] Third embodiment

[0105] The following reference Figures 11 to 14C An optical system according to a third embodiment of the present application will be described. Figure 11 FIG2 shows a light path schematic diagram of an optical system according to a third embodiment of the present application; Figure 12 1 shows a schematic structural diagram of an optical system 310 according to Example 1 of the third embodiment of the present application; Figure 13FIG. 3 is a schematic structural diagram of an optical system 320 according to Example 2 of the third embodiment of the present application.

[0106] like Figures 11 to 13 As shown, optical systems 310 and 320 each include a lens barrel P0, a lens assembly, a reflective assembly, and a spacer assembly disposed within the lens barrel P0. The lens assembly includes, from the first side to the second side, a first lens E1, a second lens E2, and a third lens E3. In this embodiment, the first side refers to the receiving portion side, and the second side refers to the emitting portion side. An aperture STO may be disposed between the receiving portion and the first lens E1. The reflective assembly includes a reflective polarizer RP, a quarter-wave plate QWP, and a partially reflective layer BS. The reflective polarizer RP is disposed between the receiving portion and the first lens E1, and the quarter-wave plate QWP is disposed between the second lens E2 and the third lens E3. The spacer assembly includes a first spacer P1 and a second spacer P2. In this embodiment, the first side of each element (the first lens E1, the second lens E2, the third lens E3, the reflective polarizer RP, the quarter-wave plate QWP, and the partially reflective layer BS) is referred to as the near-receiving portion side, and the second side is referred to as the near-emitting portion side.

[0107] The first lens E1 has positive optical power, with its near-receiving side S1 being concave and its near-emitting side S2 being convex. The second lens E2 has negative optical power, with its near-receiving side S3 being concave and its near-emitting side S4 being convex. The third lens E3 has positive optical power, with its near-receiving side S5 being concave and its near-emitting side S6 being convex. A reflective polarizer RP can be attached to the near-receiving side S1 of the first lens E1. A quarter-wave plate QWP can be attached to the near-receiving side S5 of the third lens E3. A partially reflective layer BS can be attached to the near-emitting side S6 of the third lens E3.

[0108] In this example, the emitting unit may be provided with a light source. Image light from the emitting unit sequentially passes through the third lens E3, the quarter-wave plate QWP, and the second lens E2, and reaches the reflective polarizer RP on the near-receiving portion side of the first lens E1. It then undergoes a first reflection at the reflective polarizer RP. The light that has undergone the first reflection passes through the first lens E1, the second lens E2, the quarter-wave plate QWP, and reaches the partially reflective layer BS on the near-emitting portion side of the third lens E3. It then undergoes a second reflection at the partially reflective layer BS. The light that has undergone the second reflection sequentially passes through the third lens E3, the quarter-wave plate QWP, the second lens E2, the first lens E1, and the reflective polarizer RP, and is ultimately projected onto the receiving portion in space. For example, the light from this optical system, after being reflected twice, is ultimately projected into the user's eyes.

[0109] Table 5 shows the basic parameters of the optical system of the third embodiment, where the units of curvature radius and thickness / distance are all in millimeters (mm). Image light from the transmitting unit passes through each element in the order of sequence numbers 21 to 1 and is ultimately projected onto a receiving unit in space, such as the human eye.

[0110]

[0111]

[0112] Table 5

[0113] In this embodiment, the total effective focal length f of the optical system is 16.93 mm, the effective focal length f1 of the first lens is 68.97 mm, the effective focal length f2 of the second lens is -959.16 mm, the effective focal length f3 of the third lens is 108.59 mm, the value of Semi-FOV, which is half of the maximum field of view angle of the optical system, is 50.0°, and the on-axis distance SAG22 from the intersection of the second side surface of the second lens and the optical axis to the effective semi-aperture vertex of the second side surface of the second lens is -2.31 mm.

[0114] In the third embodiment, the near-receiving side surface S1 and near-emitting side surface S2 of the first lens E1, the near-receiving side surface S3 and near-emitting side surface S4 of the second lens E2, and the near-receiving side surface S5 and near-emitting side surface S6 of the third lens E3 are all aspherical surfaces. Table 6 lists the conic coefficient K and the polynomial coefficients a0, a1, a2, and a3 of the aspherical mirror surfaces S1-S6 that can be used in the third embodiment.

[0115] Face number K a0 a1 a2 a3 S1 0.0000 3.54E-01 1.05E-02 0.00E+00 0.00E+00 S2 0.0000 8.96E+00 -2.52E-01 2.36E-01 -1.79E-01 S3 0.0000 1.43E+00 7.52E-02 8.56E-02 -2.73E-02 S4 -1.0000 2.75E+01 -1.18E+01 3.54E+00 8.80E-02 S5 0.0000 4.57E+00 -1.41E+00 1.16E-01 -1.06E-01 S6 0.0000 4.00E+00 9.13E-01 1.01E-01 -1.18E-01

[0116] Table 6

[0117] Figure 14A The axial chromatic aberration curves of the optical systems 310 and 320 of the third embodiment are shown, which indicate the deviation of the convergence point of light rays of different wavelengths after passing through the optical systems 310 and 320 . Figure 14B Astigmatism curves of the optical systems 310 and 320 according to the third embodiment are shown, which represent meridional field curvature and sagittal field curvature corresponding to different half field angles. Figure 14C The distortion curves of the optical systems 310 and 320 of the third embodiment are shown, which represent the distortion values ​​corresponding to different half-field angles. 14A to 14C It can be seen that the optical systems 310 and 320 provided in the third embodiment can achieve good imaging quality.

[0118] Fourth embodiment

[0119] The following reference Figures 15 to 18CAn optical system according to a fourth embodiment of the present application is described. Figure 15 FIG4 shows a light path schematic diagram of an optical system according to a fourth embodiment of the present application; Figure 16 1 shows a schematic structural diagram of an optical system 410 according to Example 1 of the fourth embodiment of the present application; Figure 17 A schematic structural diagram of an optical system 420 according to Example 2 of the fourth embodiment of the present application is shown.

[0120] like Figures 15 to 17 As shown, optical systems 410 and 420 each include a lens barrel P0, a lens assembly, a reflective assembly, and a spacer assembly disposed within the lens barrel P0. The lens assembly includes, from the first side to the second side, a first lens E1, a second lens E2, and a third lens E3. An aperture STO may be disposed between the receiving portion and the first lens E1. In this embodiment, the first side refers to the receiving portion side, and the second side refers to the transmitting portion side. The reflective assembly includes a reflective polarizer RP, a quarter-wave plate QWP, and a partially reflective layer BS. The reflective polarizer RP is disposed between the receiving portion and the first lens E1, and the quarter-wave plate QWP is disposed between the second lens E2 and the third lens E3. The spacer assembly includes a first spacer P1 and a second spacer P2. In this embodiment, the first side of each element (the first lens E1, the second lens E2, the third lens E3, the reflective polarizer RP, the quarter-wave plate QWP, and the partially reflective layer BS) is referred to as the near-receiving portion side, and the second side is referred to as the near-transmitting portion side.

[0121] The first lens E1 has positive optical power, with its near-receiving side S1 being flat and its near-emitting side S2 being convex. The second lens E2 has positive optical power, with its near-receiving side S3 being concave and its near-emitting side S4 being convex. The third lens E3 has positive optical power, with its near-receiving side S5 being concave and its near-emitting side S6 being convex. A reflective polarizer RP can be attached to the near-receiving side S1 of the first lens E1. A quarter-wave plate QWP can be attached to the near-receiving side S5 of the third lens E3. A partially reflective layer BS can be attached to the near-emitting side S6 of the third lens E3.

[0122] In this example, the emitting unit may be provided with a light source. Image light from the emitting unit sequentially passes through the third lens E3, the quarter-wave plate QWP, and the second lens E2, and reaches the reflective polarizer RP on the near-receiving portion side of the first lens E1. It then undergoes a first reflection at the reflective polarizer RP. The light that has undergone the first reflection passes through the first lens E1, the second lens E2, the quarter-wave plate QWP, and reaches the partially reflective layer BS on the near-emitting portion side of the third lens E3. It then undergoes a second reflection at the partially reflective layer BS. The light that has undergone the second reflection sequentially passes through the third lens E3, the quarter-wave plate QWP, the second lens E2, the first lens E1, and the reflective polarizer RP, and is ultimately projected onto the receiving portion in space. For example, the light from this optical system, after being reflected twice, is ultimately projected into the user's eyes.

[0123] Table 7 shows the basic parameters of the optical system of the fourth embodiment, where the units of curvature radius and thickness / distance are all in millimeters (mm). Image light from the transmitting unit passes through each element in the order of sequence numbers 21 to 1 and is ultimately projected onto a receiving unit in space, such as the human eye.

[0124]

[0125]

[0126] Table 7

[0127] In this embodiment, the total effective focal length f of the optical system is 16.60 mm, the effective focal length f1 of the first lens is 126.67 mm, the effective focal length f2 of the second lens is 216.92 mm, the effective focal length f3 of the third lens is 136.93 mm, the value of Semi-FOV, which is half of the maximum field of view angle of the optical system, is 50.0°, and the value of the on-axis distance SAG22 from the intersection of the second side surface of the second lens and the optical axis to the effective semi-aperture vertex of the second side surface of the second lens is -1.89 mm.

[0128] In the third embodiment, the near-emitting side surface S2 of the first lens E1, the near-receiving side surface S3 and near-emitting side surface S4 of the second lens E2, and the near-receiving side surface S5 and near-receiving side surface S6 of the third lens E3 are all aspherical surfaces. Table 8 lists the conic coefficient K and the polynomial coefficients a0, a1, a2, and a3 of the aspherical mirror surfaces S2-S6 that can be used in the third embodiment.

[0129] Face number K a0 a1 a2 a3 S2 5.8844 4.47E+00 -7.11E-01 1.43E-01 6.94E-02 S3 0.0000 2.26E-01 2.34E-01 6.41E-02 0.00E+00 S4 0.0000 -1.14E-01 5.43E-01 -1.77E-02 -3.50E-02 S5 0.0000 3.45E-01 2.04E-01 -3.55E-02 0.00E+00 S6 0.0000 -4.69E-01 2.00E-01 4.70E-02 1.29E-02

[0130] Table 8

[0131] Figure 18AThe axial chromatic aberration curves of the optical systems 410 and 420 according to the fourth embodiment are shown, which indicate the deviation of the convergence point of light rays of different wavelengths after passing through the optical systems 410 and 420 . Figure 18B Astigmatism curves of the optical systems 410 and 420 according to the fourth embodiment are shown, which represent meridional field curvature and sagittal field curvature corresponding to different half field angles. Figure 18C The distortion curves of the optical systems 410 and 420 of the fourth embodiment are shown, which represent the distortion values ​​corresponding to different half-field angles. 18A to 18C It can be seen that the optical systems 410 and 420 provided in the fourth embodiment can achieve good imaging quality.

[0132] Table 9 shows some basic parameters of the lens barrel P0 and spacers in various embodiments from the first to the fourth embodiments, such as d1s, d1m, D1s, D1m, d2s, D2s, D2m, d0s, d0m, D0s, D0m, EP01, CP1, EP12 and CP2. The basic parameters listed in Table 9 are as follows: Figure 1 The units of the basic parameters listed in Table 9 are all millimeters (mm).

[0133] Parameters / Example 1-1 1-2 2-1 2-2 3-1 3-2 4-1 4-2 d1s 50.410 52.443 45.154 44.952 45.471 45.471 46.259 46.259 d1m 51.550 52.443 46.122 45.598 45.471 45.471 46.780 46.780 D1s 53.087 55.369 47.830 47.474 49.160 48.860 48.935 48.935 D1m 53.952 55.369 49.024 48.300 49.160 48.860 49.532 49.532 d2s 52.675 52.675 47.506 49.718 46.671 46.671 46.481 46.481 D2s 55.351 55.351 50.183 53.410 49.347 49.047 49.772 50.072 D2m 56.936 56.536 50.695 53.410 50.157 50.157 50.369 50.669 d0s 45.912 48.274 44.490 44.270 45.564 45.564 46.272 46.272 d0m 59.580 58.680 53.278 54.473 52.473 52.307 52.502 52.502 D0s 54.281 54.281 49.381 49.161 50.456 50.456 51.163 51.163 D0m 61.990 60.880 55.478 56.673 54.673 54.507 54.702 54.532 EP01 3.119 3.885 3.219 2.968 2.576 2.419 2.988 2.699 CP1 1.004 0.100 1.561 1.561 0.100 0.100 2.554 2.354 EP12 1.015 1.252 1.740 2.698 2.696 2.496 1.585 1.785 CP2 1.331 1.281 1.330 0.100 2.630 2.730 1.401 1.401

[0134] Table 9 In summary, Table 10 shows the values ​​of the conditional expressions of the respective examples in the first to fourth embodiments.

[0135] Conditional formula / Example 1-1 1-2 2-1 2-2 3-1 3-2 4-1 4-2 |R4×CT2| / (D2m×CP2) 14.80 15.48 4.69 59.25 0.61 0.59 6.20 6.16 f1 / f 29.68 29.68 23.70 23.70 4.07 4.07 7.63 7.63 f2 / f 5.29 5.29 3.98 3.98 -56.66 -56.66 13.07 13.07 f3 / f 20.39 20.39 28.67 28.67 6.41 6.41 8.25 8.25 TAN(Semi-FOV)×(d0m-d0s) / f 0.86 0.65 0.67 0.78 0.49 0.47 0.45 0.45 f1 / (D1s+D1m) 4.42 4.27 3.82 3.87 0.70 0.71 1.29 1.29 (d1s+d1m) / f 6.40 6.58 5.84 5.79 5.37 5.37 5.60 5.60 <![CDATA[(EP01+CP1) / (CT1+T12+d RP )]]> 0.98 0.95 1.21 1.14 0.57 0.54 1.73 1.57 |f1+f2| / (D1m+D2s) 5.10 5.03 4.36 4.25 9.04 9.09 3.46 3.45 |R3×T12| / (d2s×CP2) 0.57 0.60 2.49 31.61 0.16 0.15 13.96 13.96 |f2×T23| / |EP12×SAG22| 28.96 23.46 4.55 2.93 61.54 66.47 39.05 34.67 <![CDATA[f3 / (d QWP +CT3+CP2+EP12)]]> 50.82 49.37 75.83 79.48 10.54 10.64 19.24 18.72 (R5+R6) / (D0s+D0m) -1.26 -1.27 -1.19 -1.18 -1.23 -1.23 -2.28 -2.29

[0136] Table 10

[0137] The present application also provides an optical device, which can be an independent 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.

[0138] The above description is merely a preferred embodiment of the present application and an illustration 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 the technical solutions formed by the specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the inventive concept. For example, a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An optical system, characterized in that include: A lens assembly comprising a first lens having positive refractive power, a second lens, and a third lens having positive refractive power, arranged in sequence from a first side to a second side along an optical axis; the second side surface of the second lens is convex; the first side surface of the third lens is concave, and the second side surface is convex; a reflective assembly comprising a reflective polarizing element, a quarter-wave plate, and a partially reflective layer; the reflective polarizing element is disposed on the first side surface or the second side surface of the first lens, the quarter-wave plate is disposed on the first side surface of the third lens, and the partially reflective layer is disposed on the first side surface or the second side surface of the third lens; a spacer set comprising a second spacer disposed between the second lens and the third lens and in contact with a second side surface of the second lens; as well as a lens barrel, wherein the lens group, the reflective assembly and the spacer group are placed in the lens barrel, wherein the number of lenses having optical power in the optical system is three; a curvature radius R4 of the second side surface of the second lens, a center thickness CT2 of the second lens on the optical axis, an outer diameter D2m of the second side surface of the second spacer, and a maximum thickness CP2 of the second spacer satisfy the following conditions: 0.59≤|R4×CT2| / (D2m×CP2)≤59.25; The effective focal length f1 of the first lens and the total effective focal length f of the optical system satisfy the following conditions: 4.07≤f1 / f≤29.68; The effective focal length f3 of the third lens and the total effective focal length f of the optical system satisfy the following: 6.41≤f3 / f≤28.

67.

2. The optical system according to claim 1, wherein: The first side surface of the first lens is configured as one of a convex surface, a concave surface, or a flat surface at the paraxial position, and the second side surface of the first lens is configured as a convex surface or a flat surface at the paraxial position.

3. The optical system according to claim 1, wherein: The effective focal length f2 of the second lens and the total effective focal length f of the optical system satisfy the following: -56.66≤f2 / f≤13.

07.

4. The optical system according to claim 1, wherein: The total effective focal length f of the optical system, half of the maximum field of view Semi-FOV of the optical system, the inner diameter d0s of the first side end surface of the lens barrel and the inner diameter d0m of the second side end surface of the lens barrel satisfy: 0.45≤TAN(Semi-FOV)×(d0m-d0s) / f≤0.

86.

5. The optical system according to any one of claims 1 to 4, characterized in that The spacer set further includes a first spacer disposed between the first lens and the second lens and in contact with the second side surface of the first lens. The effective focal length f1 of the first lens, the outer diameter D1s of the first side surface of the first spacer, and the outer diameter D1m of the second side surface of the first spacer satisfy the following conditions: 0.70≤f1 / (D1s+D1m)≤4.

42.

6. The optical system according to any one of claims 1 to 4, characterized in that The spacer set further includes a first spacer disposed between the first lens and the second lens and in contact with the second side surface of the first lens. The total effective focal length f of the optical system, the inner diameter d1s of the first side surface of the first spacer, and the inner diameter d1m of the second side surface of the first spacer satisfy the following relationship: 5.37≤(d1s+d1m) / f≤6.

58.

7. The optical system according to any one of claims 1 to 4, characterized in that The spacer set further includes a first spacer disposed between the first lens and the second lens and in contact with the second side surface of the first lens. wherein the interval EP01 between the first side end surface of the lens barrel and the first spacer along the optical axis, the maximum thickness CP1 of the first spacer, the center thickness CT1 of the first lens on the optical axis, the air interval T12 between the first lens and the second lens on the optical axis, and the center thickness d12 of the reflective polarizing element on the optical axis are the same as ... RP Satisfies: 0.5<(EP01+CP1) / (CT1+T12+d RP )≤1.

73.

8. The optical system according to any one of claims 1 to 4, characterized in that The spacer set further includes a first spacer disposed between the first lens and the second lens and in contact with the second side surface of the first lens. The effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the outer diameter D1m of the second side surface of the first spacer, and the outer diameter D2s of the first side surface of the second spacer satisfy: 3.45≤|f1+f2| / (D1m+D2s)≤9.

09.

9. The optical system according to any one of claims 1 to 4, characterized in that The curvature radius R3 of the first side surface of the second lens, the air gap T12 between the first lens and the second lens on the optical axis, the inner diameter d2s of the first side surface of the second spacer and the maximum thickness CP2 of the second spacer satisfy: 0.15≤|R3×T12| / (d2s×CP2)≤31.

61.

10. The optical system according to any one of claims 1 to 4, characterized in that The spacer set further includes a first spacer disposed between the first lens and the second lens and in contact with the second side surface of the first lens. Among them, the effective focal length f2 of the second lens, the air gap T23 between the second lens and the third lens on the optical axis, the interval EP12 between the first spacer and the second spacer along the optical axis, and the on-axis distance SAG22 from the intersection of the second side surface of the second lens and the optical axis to the effective semi-aperture vertex of the second side surface of the second lens satisfy: 2.93≤|f2×T23| / |EP12×SAG22|≤66.

47.

11. The optical system according to any one of claims 1 to 4, characterized in that The spacer set further includes a first spacer disposed between the first lens and the second lens and in contact with the second side surface of the first lens. Among them, the effective focal length f3 of the third lens, the center thickness CT3 of the third lens on the optical axis, and the center thickness d of the quarter-wave plate on the optical axis are QWP The interval EP12 between the first spacer and the second spacer along the optical axis and the maximum thickness CP2 of the second spacer satisfy the following conditions: 10.54≤f3 / (d QWP +CT3+CP2+EP12)≤79.

48.

12. The optical system according to any one of claims 1 to 4, characterized in that The curvature radius R5 of the first side surface of the third lens, the curvature radius R6 of the second side surface of the third lens, the outer diameter D0s of the first side end surface of the lens barrel and the outer diameter D0m of the second side end surface of the lens barrel satisfy: -2.29≤(R5+R6) / (D0s+D0m)≤-1.18.

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