Optical system

Abstract

The present application discloses an optical system, which sequentially includes, along the optical axis, from the first side to the second side: a first lens with a positive optical power; a second lens with a positive optical power, the second side surface of which is convex; and a third lens with a positive optical power, the first side surface of which is concave and the second side surface of which is convex; wherein, the optical system further includes a reflective polarizing element and a quarter-wave plate, and the reflective polarizing element and the quarter-wave plate are attached to the first side surface or the second side surface of the first lens; the total effective focal length f of the optical system and the radius of curvature R4 of the second side surface of the second lens satisfy: -0.6 < f / R4 < 0; and the total effective focal length f of the optical system, the effective focal length f2 of the second lens, the effective semi-aperture T2a2 from the optical center of the second side surface of the second lens to the upper edge of the effective diameter profile and the effective semi-aperture T2c2 from the optical center of the second side surface of the second lens to the lower edge of the effective diameter profile satisfy: 0 < (f / f2) × (T2c2 / T2a2) < 0.6.

Description

Technical Field

[0001] This application relates to the field of optical devices, and particularly to a catadioptric optical system. Background Art

[0002] The optical systems of virtual reality devices are mainly divided into three types: optical systems using aspherical lenses, optical systems using Fresnel lenses, and catadioptric optical systems. Among them, the catadioptric optical system is a major innovation in the optical system itself and reserves space for the overall design of virtual reality devices, and has become the mainstream trend of research and development.

[0003] The catadioptric optical system shortens the body length of the optical system by refracting the optical path, thereby shifting the center of gravity of the virtual reality device backward and improving the user's wearing experience. However, the existing catadioptric optical systems usually use two lenses, which results in a relatively blurred outer field of view of the catadioptric optical system, thereby affecting the imaging quality of the catadioptric optical system. Summary of the Invention

[0004] 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.

[0005] In a first aspect of this application, there is provided such an optical system, which sequentially includes, along the optical axis from the first side to the second side: a first lens with positive optical power; a second lens with positive optical power, whose second side is convex; and a third lens with positive optical power, whose first side is concave and second side is convex; wherein, the optical system further includes a reflective polarizing element and a quarter-wave plate, and the reflective polarizing element and the quarter-wave plate are attached to the first side or the second side of the first lens; the total effective focal length f of the optical system and the radius of curvature R4 of the second side of the second lens satisfy: -0.6 < f / R4 < 0; and the total effective focal length f of the optical system, the effective focal length f2 of the second lens, the effective semi-aperture T2a2 from the optical center of the second side of the second lens to the upper edge of the effective diameter contour and the effective semi-aperture T2c2 from the optical center of the second side of the second lens to the lower edge of the effective diameter contour satisfy: 0 < (f / f2)×(T2c2 / T2a2) < 0.6.

[0006] According to an exemplary embodiment of this application, the radius of curvature R3 of the first side of the second lens, the radius of curvature R4 of the second side of the second lens, the effective semi-aperture T2b1 from the optical center of the first side of the second lens to the left edge of the effective diameter contour and the effective semi-aperture T2b2 from the optical center of the second side of the second lens to the left edge of the effective diameter contour satisfy: 0.2 < |R4 / R3|×(T2b2 / T2b1) < 1.0.

[0007] According to an exemplary embodiment of this application, the effective half-aperture T2a1 from the optical center of the first side of the second lens to the upper edge of the effective diameter profile satisfies the same condition as the effective half-aperture T1a1 from the optical center of the first side of the first lens to the upper edge of the effective diameter profile: 0.8 <T2a1 / T1a1<1.3。

[0008] According to an exemplary embodiment of this application, the effective half-aperture T2c1 from the optical center of the first side of the second lens to the lower edge of the effective diameter profile and the effective half-aperture T1c2 from the optical center of the second side of the first lens to the lower edge of the effective diameter profile satisfy: 0.9 <T2c1 / T1c2<1.3。

[0009] According to an exemplary embodiment of this application, the effective half-aperture T2d1 from the optical center of the first side of the second lens to the right edge of the effective diameter profile and the center thickness CT2 of the second lens on the optical axis satisfy: 2.3 <T2d1 / CT2<6.0。

[0010] According to an exemplary embodiment of this application, the axial distance T12 between the second side surface of the first lens and the first side surface of the second lens, the effective half-aperture T2b1 from the optical center of the first side surface of the second lens to the left edge of the effective diameter profile, and the effective half-aperture T1b2 from the optical center of the second side surface of the first lens to the left edge of the effective diameter profile satisfy: 0.7mm <T12×(T2b1 / T1b2)<1.3mm。

[0011] According to an exemplary embodiment of this application, the center thickness CT1 of the first lens on the optical axis, the center thickness CTR of the reflective polarizing element on the optical axis, the center thickness CTQ of the quarter-wave plate on the optical axis, and the combined focal length F1 of the first lens, the reflective polarizing element, and the quarter-wave plate satisfy: 0 < (CT1 + CTR + CTQ) / F1 < 0.06.

[0012] According to an exemplary embodiment of this application, the axial distance TD between the first side surface of the first lens and the second side surface of the third lens, the entrance pupil diameter EPD of the optical system, the effective half-aperture T2a2 from the optical center of the second side surface of the second lens to the upper edge of the effective diameter profile, and the effective half-aperture T2d2 from the optical center of the second side surface of the second lens to the right edge of the effective diameter profile satisfy: 2.2 < (TD / EPD) × (T2a2 / T2d2) < 3.5.

[0013] According to an exemplary embodiment of this application, the effective focal length f1 of the first lens and the effective focal length f3 of the third lens satisfy: -0.3<(f1-f3) / (f1+f3)<0.2.

[0014] According to an exemplary embodiment of the present application, the Abbe number V2 of the second lens, the effective semi-aperture T2d1 from the optical center of the first side of the second lens to the right edge of the effective diameter profile, and the effective semi-aperture T2a1 from the optical center of the first side of the second lens to the upper edge of the effective diameter profile satisfy: 42.9 < V2 / (T2d1 / T2a1) < 47.

[0015] According to an exemplary embodiment of the present application, the radius of curvature R6 of the second side of the third lens, the total effective focal length f of the optical system, and the maximum semi-field angle Semi-FOV of the optical system satisfy: -3.6 < R6 / (f×tan(Semi-FOV)) < -3.1.

[0016] The second aspect of the present application provides an optical system that sequentially includes, along the optical axis from the first side to the second side: a first lens with positive optical power; a second lens with positive optical power, the second side of which is convex; and a third lens with positive optical power, the first side of which is concave and the second side is convex; wherein the optical system further includes a reflective polarizing element and a quarter-wave plate, and the reflective polarizing element and the quarter-wave plate are attached to the first side or the second side of the first lens; the total effective focal length f of the optical system and the radius of curvature R4 of the second side of the second lens satisfy: -0.6 < f / R4 < 0; and the on-axis distance TD from the first side of the first lens to the second side of the third lens, the entrance pupil diameter EPD of the optical system, the effective semi-aperture T2a2 from the optical center of the second side of the second lens to the upper edge of the effective diameter profile, and the effective semi-aperture T2d from the optical center of the second side of the second lens to the right edge of the effective diameter profile satisfy: 2.2 < (TD / EPD)×(T2a2 / T2d2) < 3.5.

[0017] The optical system provided by the present application uses three lenses. By reasonably configuring the optical powers of the three lenses and making the optical system satisfy "0.6 < f / R4 < 0", the imaging quality of the optical system can be improved. At the same time, by controlling the ratio of the total effective focal length of the optical system to the effective focal length of the second lens and the ratio of the effective semi-apertures from the optical center of the second side of the second lens to the lower and upper edges of the effective diameter profile, and controlling the product of these two ratios within a reasonable range, it is beneficial to constrain the shape of the second lens to ensure the molding of the second lens; it is also beneficial to constrain the field angle of the optical system, enabling the optical system to achieve the characteristic of a large field angle, effectively constraining the light input of the system, and making more efficient use of light, thereby improving the imaging quality of the optical system. Description of the Drawings

[0018] Other features, objects, and advantages of the present application will become more apparent by reading the detailed description of the non-limiting embodiments made with reference to the following drawings. Among them:

[0019] Figure 1 A schematic diagram of the structure of an optical system according to Embodiment 1, 2 or 3 of this application is shown;

[0020] Figures 2A to 2C The on-axis chromatic aberration curves, astigmatism curves, and distortion curves of the optical systems according to Embodiments 1, 2, or 3 of this application are shown respectively.

[0021] Figure 3 A schematic diagram of the structure of an optical system according to Embodiments 4, 5, or 6 of this application is shown;

[0022] Figures 4A to 4C The on-axis chromatic aberration curves, astigmatism curves, and distortion curves of the optical systems according to embodiments 4, 5, or 6 of this application are shown respectively.

[0023] Figure 5 A schematic diagram of the structure of an optical system according to Embodiments 7, 8, or 9 of this application is shown;

[0024] Figures 6A to 6C The on-axis chromatic aberration curves, astigmatism curves, and distortion curves of the optical systems according to embodiments 7, 8, or 9 of this application are shown respectively.

[0025] Figure 7A A schematic diagram of the structure of the first side of the first lens according to this application is shown;

[0026] Figure 7B A schematic diagram of the structure of the second side of the first lens according to this application is shown;

[0027] Figure 8A A schematic diagram of the structure of the first side of the second lens according to this application is shown; and

[0028] Figure 8B A schematic diagram of the structure of the second side of the second lens according to this application is shown. Detailed Implementation

[0029] 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.

[0030] It should be noted that in this specification, the terms "first," "second," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens.

[0031] 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.

[0032] 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 screen side) is called the second side surface of the lens.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] The features, principles and other aspects of this application are described in detail below.

[0037] refer to Figure 1 , Figure 3 and Figure 5The first aspect of this application provides an optical system comprising a first lens, a second lens, and a third lens arranged sequentially along an optical axis from a first side to a second side. The first lens may have positive optical power. The second lens may have positive optical power, and its second side may be convex. The third lens may have positive optical power, and its first side may be concave, and its second side may be convex. Properly configuring the optical powers of each lens is beneficial for improving the imaging quality of the optical system.

[0038] In an exemplary embodiment, the optical system may further include a reflective polarizing element and a quarter-wave plate, which are attached to a first side or a second side of the first lens.

[0039] In an exemplary embodiment, the first side may be, for example, the human eye side, and the second side may be, for example, the display screen side. Accordingly, the first side of each element (first lens, second lens, third lens, reflective polarizing element, and quarter-wave plate) may be referred to as the near-human eye side, and the second side may be referred to as the near-screen side.

[0040] In an exemplary embodiment, the second side surface of the first lens may be a plane. A reflective polarizing element and a quarter-wave plate are bonded and attached to the second side surface of the first lens, wherein the reflective polarizing element is closer to the first lens than the quarter-wave plate. By combining the reflective polarizing element and the quarter-wave plate together and then attaching them to the second side plane of the first lens, one lamination process can be reduced, the lamination process difficulty can be lowered, the lamination quality can be improved, and thus the external field-of-view performance of the optical system can be improved.

[0041] In an exemplary embodiment, the first side surface of the first lens may be a plane. A reflective polarizing element and a quarter-wave plate are bonded and attached to the first side surface of the first lens, wherein the quarter-wave plate is closer to the first lens than the reflective polarizing element. By combining the reflective polarizing element and the quarter-wave plate together and then attaching them to the first side surface of the first lens, one lamination process can be reduced, the lamination process difficulty can be lowered, the lamination quality can be improved, and thus the external field-of-view performance of the optical system can be improved.

[0042] In an exemplary implementation, reference Figure 1 , Figure 3 and Figure 5 The optical system may also include a partial reflective layer, which can be attached to the first or second side of the third lens. The partial reflective layer has a semi-transmissive and semi-reflective effect on light. By setting a partial reflective layer on the first or second side of the third lens, and combining it with a reflective polarizing element and a quarter-wave plate, light can be refracted multiple times, effectively reducing the overall length of the optical system.

[0043] In an exemplary implementation, reference Figure 1 , Figure 3 and Figure 5 The optical system may also include an aperture stop, which is positioned between the first side and the first lens. The image light on the display screen is refracted and reflected multiple times by the third lens, the second lens, the quarter-wave plate, the reflective polarizing element, and the first lens before finally being projected onto the user's eyes.

[0044] In an exemplary embodiment, an image surface may be provided on the second side of the optical system, and a display screen may be provided on the image surface. Image light from the display screen sequentially passes through a third lens, a second lens, and a quarter-wave plate, reaching a reflective polarizing element on the second side of the first lens, and is then reflected at the reflective polarizing element to form a first reflected image light. The first reflected image light passes through the quarter-wave plate, the second lens, and the third lens, reaching a partial reflective layer on the second side of the third lens, and is then reflected at the partial reflective layer to form a second reflected image light. The second reflected image light sequentially passes through the third lens, the second lens, the quarter-wave plate, the reflective polarizing element, and the first lens to the aperture stop and is finally projected into the user's eye. In one example, the first reflected image light passes through the quarter-wave plate and the second lens, reaching a partial reflective layer on the first side of the third lens, and is then reflected at the partial reflective layer to form the second reflected image light. In another example, image light from the display screen sequentially passes through a third lens, a second lens, a first lens, and a quarter-wave plate to reach a reflective polarizing element, where it is reflected to form the first reflected image light. The first reflected image light then passes through the quarter-wave plate, the first lens, the second lens, and the third lens, reaching a partial reflective layer on the second side of the third lens, where it is reflected again to form the second reflected image light. The optical system provided in this application folds the required optical path length without affecting projection quality through a combination of light reflection and refraction, effectively shortening the overall length of the optical system.

[0045] In an exemplary embodiment, the total effective focal length f of the optical system and the radius of curvature R4 of the second side surface of the second lens may satisfy: -0.6 < f / R4 < 0; and the total effective focal length f of the optical system, the effective focal length f2 of the second lens, the effective semi-aperture T2a2 from the optical center of the second side surface of the second lens to the upper edge of the effective diameter profile, and the effective semi-aperture T2c2 from the optical center of the second side surface of the second lens to the lower edge of the effective diameter profile may satisfy: 0 < (f / f2)×(T2c2 / T2a2) < 0.6. By making the optical system satisfy "0.6 < f / R4 < 0", the imaging quality of the optical system can be improved. At the same time, by controlling the ratio of the total effective focal length of the optical system to the effective focal length of the second lens and the ratio of the effective semi-apertures from the optical center of the second side surface of the second lens to the lower and upper edges of the effective diameter profile, and controlling the product of these two ratios within a reasonable range, it is beneficial to constrain the shape of the second lens to ensure the molding of the second lens; it is also beneficial to constrain the field angle of the optical system, enabling the optical system to achieve the characteristic of a large field angle, effectively constraining the light input amount of the system, and making more efficient use of light, thereby improving the imaging quality of the optical system.

[0046] In an exemplary embodiment, the radius of curvature R3 of the first side surface of the second lens, the radius of curvature R4 of the second side surface of the second lens, the effective semi-aperture T2b1 from the optical center of the first side surface of the second lens to the left edge of the effective diameter profile, and the effective semi-aperture T2b2 from the optical center of the second side surface of the second lens to the left edge of the effective diameter profile may satisfy: 0.2 < |R4 / R3|×(T2b2 / T2b1) < 1.0. By controlling the ratio of the radius of curvature of the second side surface and the first side surface of the second lens and the ratio of the effective semi-apertures from the optical centers of the second side surface and the first side surface of the second lens to the left edge of the effective diameter profile, and constraining the product of these two ratios within a reasonable range, it is beneficial to correct off-axis aberration and improve the overall image quality of the optical system; at the same time, it is also beneficial to constrain the maximum outer shape of the second lens, achieve the compactness of the lens structure, and ensure the machinability of the second lens.

[0047] In an exemplary embodiment, the effective semi-aperture T2a1 from the optical center of the first side surface of the second lens to the upper edge of the effective diameter profile and the effective semi-aperture T1a1 from the optical center of the first side surface of the first lens to the upper edge of the effective diameter profile may satisfy: 0.8 < T2a1 / T1a1 < 1.3. By controlling the ratio of the effective semi-apertures from the optical centers of the first side surfaces of the second lens and the first lens to the upper edge of the effective diameter profile, it is beneficial to constrain the field angle of the upper edge of the optical system, and further enable the optical system to achieve the characteristic of a large field angle.

[0048] In an exemplary embodiment, the effective semi-aperture T2c1 from the optical center of the first side of the second lens to the lower edge of the effective diameter profile and the effective semi-aperture T1c2 from the optical center of the second side of the first lens to the lower edge of the effective diameter profile may satisfy: 0.9 < T2c1 / T1c2 < 1.3. By controlling the ratio of the effective semi-aperture from the optical center of the first side of the second lens to the lower edge of the effective diameter profile to the effective semi-aperture from the optical center of the second side of the first lens to the lower edge of the effective diameter profile, it is beneficial to reduce the step difference in the radial direction of the optical system and improve the assembly yield of the optical system.

[0049] In an exemplary embodiment, the effective semi-aperture T2d1 from the optical center of the first side of the second lens to the right edge of the effective diameter profile and the central thickness CT2 of the second lens on the optical axis may satisfy: 2.3 < T2d1 / CT2 < 6.0. By controlling the ratio of the effective semi-aperture from the optical center of the first side of the second lens to the right edge of the effective diameter profile to the central thickness of the second lens on the optical axis, it is beneficial to improve the machinability of the second lens, increase the optical path of light in the second lens, and shorten the body length of the optical system; at the same time, it is also beneficial to constrain the effective focal length of the second lens and limit the shape of the second lens.

[0050] In an exemplary embodiment, the axial distance T12 from the second side of the first lens to the first side of the second lens, the effective semi-aperture T2b1 from the optical center of the first side of the second lens to the left edge of the effective diameter profile, and the effective semi-aperture T1b2 from the optical center of the second side of the first lens to the left edge of the effective diameter profile may satisfy: 0.7 mm < T12 × (T2b1 / T1b2) < 1.3 mm. By controlling the above conditional formula, it is beneficial to control the contribution of the aberrations of the first lens and the second lens and balance the aberrations generated by other optical elements, ensuring that the aberrations of the optical system are within a reasonable range; at the same time, it is also beneficial to control the apertures of the first lens and the second lens and make the apertures of both within a certain range to achieve the best forming structure, thereby improving the assembly stability of the optical system.

[0051] In an exemplary embodiment, the central thickness CT1 of the first lens on the optical axis, the central thickness CTR of the reflective polarizing element on the optical axis, the central thickness CTQ of the quarter-wave plate on the optical axis, and the combined focal length F1 of the first lens, the reflective polarizing element, and the quarter-wave plate satisfy: 0 < (CT1 + CTR + CTQ) / F1 < 0.06. By controlling the ratio of the sum of the central thicknesses of the first lens, the reflective polarizing element, and the quarter-wave plate to the combined focal length of the first lens, the reflective polarizing element, and the quarter-wave plate, the optical power of the first lens can be constrained. Coupled with a reasonable central thickness of the first lens on the optical axis, it is beneficial to constrain the focal length of the optical system, thereby constraining the field angle of the optical system, enabling the optical system to achieve the characteristic of a wide angle; at the same time, it can also balance the aberrations generated by other optical elements, ensuring that the aberrations of the optical system are within a reasonable range.

[0052] In an exemplary embodiment, the axial distance TD from the first side of the first lens to the second side of the third lens, the entrance pupil diameter EPD of the optical system, the effective semi-aperture T2a2 from the optical center of the second side of the second lens to the upper edge of the effective diameter profile, and the effective semi-aperture T2d2 from the optical center of the second side of the second lens to the right edge of the effective diameter profile satisfy: 2.2 < (TD / EPD)×(T2a2 / T2d2) < 3.5. By controlling the above conditional expression, it is beneficial to constrain the overall size of the optical system for later matching with the module; at the same time, it is also beneficial to balance the aberrations of the optical system, especially the lateral aberrations, and to constrain the angle of the light rays to avoid the generation of stray light at the end of the optical system.

[0053] In an exemplary embodiment, the effective focal length f1 of the first lens and the effective focal length f3 of the third lens satisfy: -0.3 < (f1 - f3) / (f1 + f3) < 0.2. By controlling the above conditional expression, the effective focal lengths of the first lens and the third lens can be respectively constrained within a certain range, and positive spherical aberration is generated. The generated positive spherical aberration can be balanced with the negative spherical aberration generated by other lenses, so that the imaging quality of the optical system on the axis is good.

[0054] In an exemplary embodiment, the Abbe number V2 of the second lens, the effective semi-aperture T2d1 from the optical center of the first side of the second lens to the right edge of the effective diameter profile, and the effective semi-aperture T2a1 from the optical center of the first side of the second lens to the upper edge of the effective diameter profile satisfy: 42.9 < V2 / (T2d1 / T2a1) < 47. By controlling the above conditional expression, the shape of the second lens can be effectively constrained, which is beneficial to filtering out the redundant light generated at the edge after the light passes through the second lens by refraction and reflection, only ensuring that the effective light passes through the second lens, improving the overall image quality of the optical system; at the same time, it can also correct the chromatic aberration of the optical system and improve the user's wearing experience.

[0055] In an exemplary embodiment, the radius of curvature R6 of the second side surface of the third lens, the total effective focal length f of the optical system, and the maximum semi-field angle Semi-FOV of the optical system may satisfy: -3.6 < R6 / (f × tan(Semi-FOV)) < -3.1. By controlling the above conditional formula, it is beneficial to restrict the field angle of the optical system, enabling the optical system to achieve the characteristic of a large field angle, and further restricting the body length and radial height of the optical system while ensuring the viewing angle of the optical system.

[0056] The optical system according to the above embodiment of the present application may employ multiple lenses, such as the three lenses described above. By reasonably allocating the parameters of the reflective polarizing element, quarter-wave plate, and each lens, the body length of the optical system can be reduced, the large field angle of the optical system can be achieved, and the imaging quality, assembly stability, assembly yield, and wearing experience of the optical system can be improved. The optical system configured as above has characteristics such as miniaturization, large field angle, and good imaging quality, and can well meet the usage requirements of various portable electronic products in the projection scenario.

[0057] In an embodiment of the present application, at least one of the surfaces of the first lens, the second lens, and the third lens is an aspherical surface. The characteristic of an aspherical lens is that the curvature continuously changes from the center of the lens to the periphery of the lens. Different from a spherical lens with a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has better radius-of-curvature characteristics and has the advantages of improving distortion aberration and astigmatism aberration. After using an aspherical lens, it is possible to eliminate the aberration that appears during imaging as much as possible, thereby improving the imaging quality.

[0058] However, those skilled in the art should understand that without departing from the technical solution claimed in the present application, the number of lenses constituting the optical system can be changed to obtain the various results and advantages described in this specification.

[0059] Reference Figure 1 、 Figure 3 and Figure 5 , a second aspect of the present application provides such an optical system, which includes a first lens, a second lens, and a third lens arranged in sequence along the optical axis from the first side to the second side. The first lens has a positive optical power. The second lens has a positive optical power, and its second side surface may be convex. The third lens has a positive optical power, its first side surface may be concave, and its second side surface may be convex. The optical system further includes a reflective polarizing element and a quarter-wave plate, and the reflective polarizing element and the quarter-wave plate are attached to the first side surface or the second side surface of the first lens.

[0060] Among them, the total effective focal length f of the optical system and the radius of curvature R4 of the second side of the second lens satisfy: -0.6 < f / R4 < 0; and the on-axis distance TD from the first side of the first lens to the second side of the third lens, the entrance pupil diameter EPD of the optical system, the effective semi-aperture T2a2 from the optical center of the second side of the second lens to the upper edge of the effective diameter profile, and the effective semi-aperture T2d2 from the optical center of the second side of the second lens to the right edge of the effective diameter profile satisfy: 2.2 < (TD / EPD)×(T2a2 / T2d2) < 3.5. The optical system provided in this application uses three lenses. By reasonably configuring the optical powers of the three lenses and making the optical system satisfy "0.6 < f / R4 < 0", the imaging quality of the optical system can be improved. At the same time, controlling the ratio of the on-axis distance from the first side of the first lens to the second side of the third lens to the entrance pupil diameter of the optical system and the ratio of the effective semi-apertures from the optical center of the second side of the second lens to the upper edge and the right edge of the effective diameter profile, and controlling the product of these two ratios within a reasonable range is beneficial to restricting the overall size of the optical system for later matching with the module; it is also beneficial to balance the aberrations of the optical system, especially the lateral aberration, and to restrict the angle of light rays to avoid the generation of tail-end stray light.

[0061] The specific embodiments of the optical system applicable to the above embodiments will be further described below with reference to the drawings.

[0062] Example 1

[0063] The following refers to Figures 1 to 2C Describe the optical system according to Embodiment 1 of the present application.

[0064] As Figure 1 shown, the optical system includes a first lens E1, a second lens E2, and a third lens E3 arranged in sequence along the optical axis from the first side to the second side. A reflective polarizing element RP and a quarter-wave plate QWP are attached to the second side of the first lens E1. A partial reflection layer BS is attached to the second side of the third lens E3. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side. The first sides of each element (the first lens E1, the reflective polarizing element RP, the quarter-wave plate QWP, the second lens E2, and the third lens E3) are all referred to as the near-human-eye sides, and the second sides are all referred to as the near-screen sides.

[0065] The first lens E1 has positive optical power, with its near-eye side S1 being convex and its near-screen side S2 being flat. The reflective polarizing element RP has a near-eye side and a near-screen side, with its near-eye side attached to the near-screen side S2 of the first lens E1. The quarter-wave plate QWP has a near-eye side and a near-screen side, with its near-eye side attached to the near-screen side of the reflective polarizing element RP. The second lens E2 has positive optical power, with its near-eye side S3 being convex and its near-screen side S4 being convex. The third lens E3 has positive optical power, with its near-eye side S5 being concave and its near-screen side S6 being convex. A partial reflective layer BS is attached to the near-screen side S6 of the third lens E3.

[0066] In this example, an image plane (IMG) may be provided on the second side of the optical system, and the image plane (IMG) may, for example, be a display screen. Image light from the image plane (IMG) sequentially passes through the third lens (E3), the second lens (E2), and the quarter-wave plate (QWP), and reaches the reflective polarizing element (RP) located near the screen side (S2) of the first lens (E1), where it undergoes a first reflection. The light after the first reflection passes through the quarter-wave plate (QWP), the second lens (E2), and the third lens (E3), and reaches the partial reflective layer (BS) located near the screen side (S6) of the third lens (E3), 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), and the first lens (E1) to the aperture stop and is finally projected into the user's eye. For example, the light from this optical system after two reflections is finally projected into the user's eye.

[0067] Table 1 shows the basic parameters of the optical system of Embodiment 1, where the units for radius of curvature and thickness / distance are millimeters (mm). Image light from the image plane IMG passes through each element in the order of number 19 to number 1 and is finally projected into the human eye.

[0068]

[0069] Table 1

[0070] In Example 1, the near-eye side S1 of the first lens E1, the near-eye side S3 and the near-screen side S4 of the second lens E2, and the near-eye side S5 and the near-screen side S6 of the third lens E3 are all aspherical. The surface shape x of each aspherical lens can be limited by, but is not limited to, the following aspherical formula:

[0071]

[0072] Where x is the distance vector from the vertex of the aspherical surface at a height 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, A9, and A1 that can be used for the aspherical surfaces S1, S3-S6 in Example 1. 10 A 12 A 14 A 16 A 18 and A 20 .

[0073] Face number A4 A6 A8 A10 A12 A14 A16 A18 A20 S1 5.4237E-06 -2.3989E-09 3.6552E-12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S3 -1.5885E-06 -2.0729E-09 -2.6708E-12 -8.1094E-15 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S4 1.0446E-06 1.1980E-09 8.8833E-13 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S5 -9.2231E-07 -1.5926E-09 -1.6433E-12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S6 2.8132E-07 -2.8440E-10 -1.4642E-12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0074] Table 2

[0075] Example 2

[0076] Continue to refer to Figure 1 The optical system includes a first lens E1, a second lens E2, and a third lens E3 arranged sequentially along the optical axis from the first side to the second side. A reflective polarizing element RP and a quarter-wave plate QWP are attached to the second side of the first lens E1. A partially reflective layer BS is attached to the second side of the third lens E3. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side. The first side of each element (first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, and third lens E3) is referred to as the near-human eye side, and the second side is referred to as the near-screen side.

[0077] The structure of the optical system in this embodiment is basically the same as that of the optical system in Embodiment 1. That is, the basic parameter table of the optical system in this embodiment is the same as Table 1, and the aspherical coefficient table is the same as Table 2. The difference between this embodiment and Embodiment 1 is that the effective half-aperture of the first lens and the second lens are different. For example, the effective half-aperture T1a1 from the optical center of the first side of the first lens to the upper edge of the effective diameter profile, the effective half-aperture T1b2 from the optical center of the second side of the first lens to the left edge of the effective diameter profile, the effective half-aperture T1c2 from the optical center of the second side of the first lens to the lower edge of the effective diameter profile, the effective half-aperture T2a1 from the optical center of the first side of the second lens to the upper edge of the effective diameter profile, the effective half-aperture T2b1 from the optical center of the first side of the second lens to the left edge of the effective diameter profile, and the effective half-aperture T2a1 from the optical center of the first side of the second lens to the left edge of the effective diameter profile, and the effective half-aperture T2b1 from the optical center of the first side of the second lens to the lower edge of the effective diameter profile. The parameters T2c1 (effective half-aperture at the lower edge of the profile), T2d1 (effective half-aperture from the optical center of the first side of the second lens to the right edge of the effective diameter profile), T2a2 (effective half-aperture from the optical center of the second side of the second lens to the upper edge of the effective diameter profile), T2b2 (effective half-aperture from the optical center of the second side of the second lens to the left edge of the effective diameter profile), T2c2 (effective half-aperture from the optical center of the second side of the second lens to the lower edge of the effective diameter profile), and T2d2 (effective half-aperture from the optical center of the second side of the second lens to the right edge of the effective diameter profile) are different.

[0078] Example 3

[0079] Continue to refer to Figure 1 The optical system includes a first lens E1, a second lens E2, and a third lens E3 arranged sequentially along the optical axis from the first side to the second side. A reflective polarizing element RP and a quarter-wave plate QWP are attached to the second side of the first lens E1. A partially reflective layer BS is attached to the second side of the third lens E3. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side. The first side of each element (first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, and third lens E3) is referred to as the near-human eye side, and the second side is referred to as the near-screen side.

[0080] The structure of the optical system in this embodiment is basically the same as that of the optical system in Embodiment 1. That is, the basic parameter table of the optical system in this embodiment is the same as Table 1, and the aspherical coefficient table is the same as Table 2. The difference between this embodiment and Embodiment 1 is that the effective half-apertures of the first and second side surfaces of the first and second lenses are different. For example, parameters such as T1a1, T1b2, T1c2, T2a1, T2b1, T2c1, T2d1, T2a2, T2b2, T2c2, and T2d2 are different.

[0081] Figure 2A The on-axis chromatic aberration curves of the optical systems of Embodiments 1, 2, or 3 are shown, which represent the deflection of the focal point of light of different wavelengths after passing through the optical system. Figure 2B Astigmatism curves for the optical systems of Embodiments 1, 2, or 3 are shown, representing the meridional and sagittal image plane curvatures corresponding to different field of view angles. Figure 2C The distortion curves of the optical systems of Embodiments 1, 2, or 3 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 2A to 2C It can be seen that the optical systems given in Examples 1, 2 or 3 can achieve good imaging quality.

[0082] Example 4

[0083] The following is for reference Figures 3 to 4C The optical system according to Embodiment 4 of this application is described.

[0084] like Figure 3 As shown, the optical system includes a first lens E1, a second lens E2, and a third lens E3 arranged sequentially along the optical axis from the first side to the second side. A reflective polarizing element RP and a quarter-wave plate QWP are attached to the first side of the first lens E1. A partially reflective layer BS is attached to the second side of the third lens E3. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side. The first side of each element (reflective polarizing element RP, quarter-wave plate QWP, first lens E1, second lens E2, and third lens E3) is referred to as the near-human eye side, and the second side is referred to as the near-screen side.

[0085] The first lens E1 has positive optical power, with its near-eye side S1 being flat and its near-screen side S2 being convex. Both the reflective polarizing element RP and the quarter-wave plate QWP have near-eye and near-screen sides. The near-screen side of the reflective polarizing element RP is attached to the near-eye side of the quarter-wave plate QWP, and the near-screen side of the quarter-wave plate QWP is attached to the near-eye side S1 of the first lens E1. The second lens E2 has positive optical power, with its near-eye side S3 being concave and its near-screen side S4 being convex. The third lens E3 has positive optical power, with its near-eye side S5 being concave and its near-screen side S6 being convex. A partial reflective layer BS is attached to the near-screen side S6 of the third lens E3.

[0086] In this example, an image surface IMG can be provided on the second side of the optical system, and the image surface IMG can, for example, be a display screen. Image light from the image surface IMG passes sequentially through the third lens E3, the second lens E2, the first lens E1, 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 first lens E1, the second lens E2, the third lens E3, and reaches the partial reflective layer BS located near the screen side S6 of the third lens E3, where it undergoes a second reflection. The light after the second reflection passes sequentially through the third lens E3, the second lens E2, the first lens E1, the quarter-wave plate QWP, the reflective polarizing element RP, to the aperture, and is finally projected into the user's eye. For example, the light from this optical system after two reflections is finally projected into the user's eye.

[0087] Table 3 shows the basic parameters of the optical system in Example 4, where the units for radius of curvature and thickness / distance are millimeters (mm). Image light from the image plane IMG passes through each element in the order of number 21 to number 1 and is finally projected into the human eye.

[0088]

[0089] Table 3

[0090] In Example 4, the near-screen side S2 of the first lens E1, the near-eye side S3 and near-screen side S4 of the second lens E2, and the near-eye side S5 and near-screen side S6 of the third lens E3 are all aspherical surfaces. Table 4 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical surfaces S2-S6 in Example 4. 10 A 12 A 14 A 16 A 18 and A 20 .

[0091] Face number A4 A6 A8 A10 A12 A14 A16 A18 A20 S2 -9.3366E-07 8.7462E-10 -7.0427E-12 -4.0004E-17 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S3 8.0702E-07 4.0909E-09 1.4193E-13 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S4 -6.3265E-06 -1.7551E-09 1.8243E-12 2.9923E-14 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S5 -4.7111E-06 -5.3134E-10 -5.2505E-12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S6 -4.9338E-07 3.2606E-10 -6.5003E-13 -1.0413E-15 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0092] Table 4

[0093] Example 5

[0094] Continue to refer to Figure 3The optical system includes a first lens E1, a second lens E2, and a third lens E3 arranged sequentially along the optical axis from the first side to the second side. A reflective polarizing element RP and a quarter-wave plate QWP are attached to the first side of the first lens E1. A partially reflective layer BS is attached to the second side of the third lens E3. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side. The first side of each element (reflective polarizing element RP, quarter-wave plate QWP, first lens E1, second lens E2, and third lens E3) is referred to as the near-human eye side, and the second side is referred to as the near-screen side.

[0095] The structure of the optical system in this embodiment is basically the same as that of the optical system in Embodiment 4. That is, the basic parameter table of the optical system in this embodiment is the same as that in Table 3, and the aspherical coefficient table is the same as that in Table 4. The difference between this embodiment and Embodiment 4 is that the effective half-apertures of the first and second side surfaces of the first and second lenses are different. For example, the parameters T1a1, T1b2, T1c2, T2a1, T2b1, T2c1, T2d1, T2a2, T2b2, T2c2, and T2d2 are different.

[0096] Example 6

[0097] Continue to refer to Figure 3 The optical system includes a first lens E1, a second lens E2, and a third lens E3 arranged sequentially along the optical axis from the first side to the second side. A reflective polarizing element RP and a quarter-wave plate QWP are attached to the first side of the first lens E1. A partially reflective layer BS is attached to the second side of the third lens E3. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side. The first side of each element (reflective polarizing element RP, quarter-wave plate QWP, first lens E1, second lens E2, and third lens E3) is referred to as the near-human eye side, and the second side is referred to as the near-screen side.

[0098] The structure of the optical system in this embodiment is basically the same as that of the optical system in Embodiment 4. That is, the basic parameter table of the optical system in this embodiment is the same as that in Table 3, and the aspherical coefficient table is the same as that in Table 4. The difference between this embodiment and Embodiment 4 is that the effective half-apertures of the first and second side surfaces of the first and second lenses are different. For example, the parameters T1a1, T1b2, T1c2, T2a1, T2b1, T2c1, T2d1, T2a2, T2b2, T2c2, and T2d2 are different.

[0099] Figure 4A The on-axis chromatic aberration curves of the optical systems of Embodiments 4, 5, or 6 are shown, which represent the deflection of the focal point of light of different wavelengths after passing through the optical system. Figure 4BAstigmatism curves for the optical systems of Examples 4, 5, or 6 are shown, representing the meridional and sagittal image plane curvatures corresponding to different field of view angles. Figure 4C The distortion curves of the optical systems in Examples 4, 5, or 6 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 4A to 4C It can be seen that the optical systems given in Examples 4, 5 or 6 can achieve good imaging quality.

[0100] Example 7

[0101] The following is for reference Figures 5 to 6C The optical system according to Embodiment 7 of this application is described.

[0102] like Figure 5 As shown, the optical system includes a first lens E1, a second lens E2, and a third lens E3 arranged sequentially along the optical axis from the first side to the second side. A reflective polarizing element RP and a quarter-wave plate QWP are attached to the second side of the first lens E1. A partially reflective layer BS is attached to the first side of the third lens E3. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side. The first side of each element (first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, and third lens E3) is referred to as the near-human eye side, and the second side is referred to as the near-screen side.

[0103] The first lens E1 has positive optical power, with its near-eye side S1 being convex and its near-screen side S2 being flat. The reflective polarizing element RP has a near-eye side and a near-screen side, with its near-eye side attached to the near-screen side S2 of the first lens E1. The quarter-wave plate QWP has a near-eye side and a near-screen side, with its near-eye side attached to the near-screen side of the reflective polarizing element RP. The second lens E2 has positive optical power, with its near-eye side S3 being convex and its near-screen side S4 being convex. The third lens E3 has positive optical power, with its near-eye side S5 being concave and its near-screen side S6 being convex. A partial reflective layer BS is attached to the near-eye side S5 of the third lens E3.

[0104] In this example, an image plane (IMG) may be provided on the second side of the optical system, and the image plane (IMG) may, for example, be a display screen. Image light from the image plane (IMG) sequentially passes through the third lens (E3), the second lens (E2), and the quarter-wave plate (QWP), and reaches the reflective polarizing element (RP) located on the near-screen side (S2) of the first lens (E1), where it undergoes a first reflection. The light after the first reflection passes through the quarter-wave plate (QWP), the second lens (E2), and reaches the partial reflective layer (BS) located on the near-eye side (S5) of the third lens (E3), where it undergoes a second reflection. The light after the second reflection sequentially passes through the second lens (E2), the quarter-wave plate (QWP), the reflective polarizing element (RP), the first lens (E1), to the aperture stop, and is finally projected into the user's eye. For example, the light from this optical system, after two reflections, is finally projected into the user's eye.

[0105] Table 5 shows the basic parameters of the optical system of Embodiment 7, where the units for radius of curvature and thickness / distance are millimeters (mm). Image light from the image plane IMG passes through each element in the order of number 17 to number 1 and is finally projected into the human eye.

[0106] Table 5

[0107] In Example 7, the near-eye side S1 of the first lens E1, the near-eye side S3 and the near-screen side S4 of the second lens E2, and the near-eye side S5 and the near-screen side S6 of the third lens E3 are all aspherical surfaces. Table 6 shows the higher-order coefficients A4, A6, A8, and A6 of the aspherical surfaces S1, S3-S6 that can be used in Example 7. 10 A 12 A 14 A 16 A 18 and A 20 .

[0108] Face number A4 A6 A8 A10 A12 A14 A16 A18 A20 S1 7.2366E-06 -5.2882E-09 -7.8065E-12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S3 6.0313E-07 -3.5877E-09 -9.0413E-12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S4 9.2076E-06 -2.5261E-09 1.0453E-11 -1.4568E-14 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S5 -7.1202E-07 3.0802E-09 -4.9956E-12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 S6 3.0692E-06 -2.0769E-08 -4.2219E-11 1.2862E-13 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0109] Table 6

[0110] Example 8

[0111] Continue to refer to Figure 5The optical system includes a first lens E1, a second lens E2, and a third lens E3 arranged sequentially along the optical axis from the first side to the second side. A reflective polarizing element RP and a quarter-wave plate QWP are attached to the second side of the first lens E1. A partially reflective layer BS is attached to the first side of the third lens E3. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side. The first side of each element (first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, and third lens E3) is referred to as the near-human eye side, and the second side is referred to as the near-screen side.

[0112] The structure of the optical system in this embodiment is basically the same as that of the optical system in Embodiment 7. That is, the basic parameter table of the optical system in this embodiment is the same as that in Table 5, and the aspherical coefficient table is the same as that in Table 6. The difference between this embodiment and Embodiment 7 is that the effective half-apertures of the first and second side surfaces of the first and second lenses are different. For example, the parameters T1a1, T1b2, T1c2, T2a1, T2b1, T2c1, T2d1, T2a2, T2b2, T2c2, and T2d2 are different.

[0113] Example 9

[0114] Continue to refer to Figure 5 The optical system includes a first lens E1, a second lens E2, and a third lens E3 arranged sequentially along the optical axis from the first side to the second side. A reflective polarizing element RP and a quarter-wave plate QWP are attached to the second side of the first lens E1. A partially reflective layer BS is attached to the first side of the third lens E3. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side. The first side of each element (first lens E1, reflective polarizing element RP, quarter-wave plate QWP, second lens E2, and third lens E3) is referred to as the near-human eye side, and the second side is referred to as the near-screen side.

[0115] The structure of the optical system in this embodiment is basically the same as that of the optical system in Embodiment 7. That is, the basic parameter table of the optical system in this embodiment is the same as that in Table 5, and the aspherical coefficient table is the same as that in Table 6. The difference between this embodiment and Embodiment 7 is that the effective half-apertures of the first and second side surfaces of the first and second lenses are different. For example, the parameters T1a1, T1b2, T1c2, T2a1, T2b1, T2c1, T2d1, T2a2, T2b2, T2c2, and T2d2 are different.

[0116] Figure 6A The on-axis chromatic aberration curves of the optical systems of Embodiments 7, 8, or 9 are shown, which represent the deflection of the focal point of light of different wavelengths after passing through the optical system. Figure 6BAstigmatism curves for the optical systems of Embodiments 7, 8, or 9 are shown, representing the meridional and sagittal image plane curvatures corresponding to different field of view angles. Figure 6C The distortion curves of the optical systems of Embodiments 7, 8, or 9 are shown, representing the distortion magnitude values ​​corresponding to different field of view angles. According to... Figures 6A to 6C It can be seen that the optical systems given in Examples 7, 8 or 9 can achieve good imaging quality.

[0117] Table 7 lists the basic parameters for each embodiment in Examples 1 to 9, such as the values ​​of F1, f1, f2, f3, f, EPD, TD, CTR, CTQ, Semi-FOV, T1a1, T1b2, T1c2, T2a1, T2b1, T2c1, T2d1, T2a2, T2b2, T2c2, and T2d2. The data for T1a1, T1b2, T1c2, T2a1, T2b1, T2c1, T2d1, T2a2, T2b2, T2c2, and T2d2 can be found by referring to... Figures 7A to 8B The annotation method is used to measure it.

[0118] Parameters / Examples 1 2 3 4 5 6 7 8 9 F1 (mm) 137.14 137.14 137.14 216.06 216.06 216.06 429.75 429.75 429.75 f1(mm) 137.14 137.14 137.14 216.06 216.06 216.06 429.75 429.75 429.75 f2 (mm) 119.98 119.98 119.98 593.04 593.04 593.04 54.66 54.66 54.66 f3 (mm) 233.28 233.28 233.28 176.89 176.89 176.89 672.87 672.87 672.87 f(mm) 20.64 20.64 20.64 22.96 22.96 22.96 20.47 20.47 20.47 EPD (mm) 4.50 4.50 4.50 5.00 5.00 5.00 4.50 4.50 4.50 TD(mm) 16.67 16.67 16.67 14.87 14.87 14.87 18.58 18.58 18.58 CTR(mm) 0.09 0.09 0.09 0.10 0.10 0.10 0.09 0.09 0.09 CTQ(mm) 0.09 0.09 0.09 0.10 0.10 0.10 0.09 0.09 0.09 Semi-FOV (°) 48.0 48.0 48.0 48.0 48.0 48.0 45.0 45.0 45.0 T1a1(mm) 16.79 14.10 18.24 16.32 19.44 21.12 19.01 17.50 14.69 T1b2(mm) 20.65 18.73 20.22 21.12 23.28 22.80 19.76 20.17 18.30 T1c2(mm) 21.29 21.07 22.35 23.76 24.00 25.20 21.84 20.80 20.59 T2a1(mm) 17.17 15.39 19.62 16.56 18.48 21.12 19.80 17.33 15.53 T2b1(mm) 20.96 20.07 23.42 21.60 22.56 25.20 23.63 21.15 20.25 T2c1(mm) 22.30 22.30 25.65 24.00 24.00 27.60 25.88 22.50 22.50 T2d1(mm) 20.96 20.07 23.42 21.60 22.56 25.20 23.63 21.15 20.25 T2a2(mm) 17.17 15.39 19.62 16.56 18.48 21.12 19.80 17.33 15.53 T2b2(mm) 20.96 20.07 23.42 21.60 22.56 25.20 23.63 21.15 20.25 T2c2(mm) 22.30 22.30 25.65 24.00 24.00 27.60 25.88 22.50 22.50 T2d2(mm) 20.96 20.07 23.42 21.60 22.56 25.20 23.63 21.15 20.25

[0119] Table 7 summarizes the above, and Table 8 shows the values ​​of the conditional expressions for each of the embodiments in Examples 1 to 9.

[0120] Conditional / Example 1 2 3 4 5 6 7 8 9 f / R4 -0.16 -0.16 -0.16 -0.21 -0.21 -0.21 -0.57 -0.57 -0.57 (f / f2)×(T2c2 / T2a2) 0.22 0.25 0.22 0.06 0.05 0.05 0.49 0.49 0.54 |R4 / R3|×(T2b2 / T2b1) 0.93 0.93 0.93 0.67 0.67 0.67 0.22 0.22 0.22 T2a1 / T1a1 1.02 1.09 1.08 1.01 0.95 1.00 1.04 0.99 1.06 T2c1 / T1c2 1.05 1.06 1.15 1.01 1.00 1.10 1.18 1.08 1.09 T2d1 / CT2 4.72 4.52 5.28 5.07 5.29 5.91 2.76 2.47 2.37 T12×(T2b1 / T1b2) 0.77 0.81 0.88 0.78 0.74 0.84 1.29 1.13 1.20 (CT1+CTR+CTQ) / F1 0.05 0.05 0.05 0.02 0.02 0.02 0.01 0.01 0.01 (TD / EPD)×(T2a2 / T2d2) 3.03 2.84 3.10 2.28 2.44 2.49 3.46 3.38 3.17 (f1-f3) / (f1+f3) -0.26 -0.26 -0.26 0.10 0.10 0.10 -0.22 -0.22 -0.22 V2 / (T2d1 / T2a1) 45.86 42.93 46.92 42.93 45.86 46.92 46.92 45.86 42.93 R6 / (f×tan(Semi-FOV)) -3.50 -3.50 -3.50 -3.56 -3.56 -3.56 -3.16 -3.16 -3.16

[0121] Table 8

[0122] 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 a virtual reality device. The optical device is equipped with the optical system described above.

[0123] 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, In order from the first side to the second side along the optical axis, it includes: A first lens with a positive optical power; A second lens with a positive optical power, the second side surface of which is convex; and A third lens with a positive optical power, the first side surface of which is concave and the second side surface of which is convex; Wherein, the optical system further includes a reflective polarizing element and a quarter-wave plate, and the reflective polarizing element and the quarter-wave plate are attached to the first side surface or the second side surface of the first lens; The optical system further includes: a partial reflection element, and the partial reflection element is disposed on the first side surface or the second side surface of the third lens; The total effective focal length f of the optical system and the radius of curvature R4 of the second side surface of the second lens satisfy: -0.6 < f / R4 ≤ -0.16; and The total effective focal length f of the optical system, the effective focal length f2 of the second lens, the effective semi-aperture T2a2 from the optical center of the second side surface of the second lens to the upper edge of the effective diameter profile and the effective semi-aperture T2c2 from the optical center of the second side surface of the second lens to the lower edge of the effective diameter profile satisfy: 0.05 ≤ (f / f2) × (T2c2 / T2a2) ≤ 0.54; The on-axis distance TD from the first side surface of the first lens to the second side surface of the third lens, the entrance pupil diameter EPD of the optical system, the effective semi-aperture T2a2 from the optical center of the second side surface of the second lens to the upper edge of the effective diameter profile and the effective semi-aperture T2d2 from the optical center of the second side surface of the second lens to the right edge of the effective diameter profile satisfy: 2.28 ≤ (TD / EPD) × (T2a2 / T2d2) < 3.5; The first side is the human eye side, and the second side is the display side; The number of lenses with optical power in the optical system is three.

2. The optical system according to claim 1, characterized in that, The radius of curvature R3 of the first side surface of the second lens, the radius of curvature R4 of the second side surface of the second lens, the effective semi-aperture T2b1 from the optical center of the first side surface of the second lens to the left edge of the effective diameter profile and the effective semi-aperture T2b2 from the optical center of the second side surface of the second lens to the left edge of the effective diameter profile satisfy: 0.2 < |R4 / R3| × (T2b2 / T2b1) ≤ 0.

93.

3. The optical system according to claim 1, characterized in that, The effective semi-aperture T2a1 from the optical center of the first side surface of the second lens to the upper edge of the effective diameter profile and the effective semi-aperture T1a1 from the optical center of the first side surface of the first lens to the upper edge of the effective diameter profile satisfy: 0.95 ≤ T2a1 / T1a1 ≤ 1.

09.

4. The optical system according to claim 1, characterized in that, The effective semi-aperture T2c1 from the optical center of the first side surface of the second lens to the lower edge of the effective diameter profile and the effective semi-aperture T1c2 from the optical center of the second side surface of the first lens to the lower edge of the effective diameter profile satisfy: 1.00 ≤ T2c1 / T1c2 ≤ 1.

18.

5. The optical system according to claim 1, characterized in that, The effective semi-aperture T2d1 from the optical center of the first side surface of the second lens to the right edge of the effective diameter profile and the central thickness CT2 of the second lens on the optical axis satisfy: 2.37 ≤ T2d1 / CT2 ≤ 5.

91.

6. The optical system according to any one of claims 1 to 5, characterized in that, The axial distance T12 from the second side surface of the first lens to the first side surface of the second lens, the effective semi-aperture T2b1 from the optical center of the first side surface of the second lens to the left edge of the effective diameter profile, and the effective semi-aperture T1b2 from the optical center of the second side surface of the first lens to the left edge of the effective diameter profile satisfy: 0.7 mm < T12×(T2b1 / T1b2) < 1.3 mm.

7. The optical system according to any one of claims 1 to 5, characterized in that, The central thickness CT1 of the first lens on the optical axis, the central thickness CTR of the reflective polarizing element on the optical axis, the central thickness CTQ of the quarter-wave plate on the optical axis, and the combined focal length F1 of the first lens, the reflective polarizing element, and the quarter-wave plate satisfy: 0 < (CT1 + CTR + CTQ) / F1 < 0.

06.

8. The optical system according to any one of claims 1 to 5, characterized in that, The effective focal length f1 of the first lens and the effective focal length f3 of the third lens satisfy: -0.3 < (f1 - f3) / (f1 + f3) ≤ 0.

10.

9. The optical system according to any one of claims 1 to 5, characterized in that, The Abbe number V2 of the second lens, the effective semi-aperture T2d1 from the optical center of the first side surface of the second lens to the right edge of the effective diameter profile, and the effective semi-aperture T2a1 from the optical center of the first side surface of the second lens to the upper edge of the effective diameter profile satisfy: 42.9 < V2 / (T2d1 / T2a1) ≤ 46.

92.

10. The optical system according to any one of claims 1 to 5, characterized in that, The radius of curvature R6 of the second side surface of the third lens, the total effective focal length f of the optical system, and the maximum semi-field angle Semi-FOV of the optical system satisfy: -3.6 < R6 / (f×tan(Semi-FOV)) ≤ -3.

16.

11. An optical system, characterized in that, In sequence along the optical axis from the first side to the second side, it includes: A first lens with a positive optical power; A second lens with a positive optical power, whose second side surface is convex; and A third lens with a positive optical power, whose first side surface is concave and the second side surface is convex; Wherein, the optical system further includes a reflective polarizing element and a quarter-wave plate, and the reflective polarizing element and the quarter-wave plate are attached to the first side surface or the second side surface of the first lens; The optical system further includes: a partial reflection element, and the partial reflection element is disposed on the first side surface or the second side surface of the third lens; The total effective focal length f of the optical system and the radius of curvature R4 of the second side surface of the second lens satisfy: -0.6 < f / R4 ≤ -0.16; and The axial distance TD from the first side surface of the first lens to the second side surface of the third lens, the entrance pupil diameter EPD of the optical system, the effective semi-aperture T2a2 from the optical center of the second side surface of the second lens to the upper edge of the effective diameter profile, and the effective semi-aperture T2d2 from the optical center of the second side surface of the second lens to the right edge of the effective diameter profile satisfy: 2.28 ≤ (TD / EPD)×(T2a2 / T2d2) < 3.5; The first side is the human eye side, and the second side is the display side; The number of lenses with optical power in the optical system is three.

12. The optical system according to claim 11, characterized in that, The radius of curvature R3 of the first side surface of the second lens, the radius of curvature R4 of the second side surface of the second lens, the effective half-aperture T2b1 from the optical center of the first side surface of the second lens to the left edge of the effective diameter profile, and the effective half-aperture T2b2 from the optical center of the second side surface of the second lens to the left edge of the effective diameter profile satisfy: 0.2 < |R4 / R3|×(T2b2 / T2b1)≤0.

93.

13. The optical system according to claim 11, characterized in that, The effective half-aperture T2a1 from the optical center of the first side of the second lens to the upper edge of the effective diameter profile satisfies the condition T1a1 from the optical center of the first side of the first lens to the upper edge of the effective diameter profile: 0.95≤T2a1 / T1a1≤1.

09.

14. The optical system according to claim 11, characterized in that, The effective half-aperture T2c1 from the optical center of the first side of the second lens to the lower edge of the effective diameter profile and the effective half-aperture T1c2 from the optical center of the second side of the first lens to the lower edge of the effective diameter profile satisfy: 1.00≤T2c1 / T1c2≤1.

18.

15. The optical system according to claim 11, characterized in that, The effective half-aperture T2d1 from the optical center of the first side of the second lens to the right edge of the effective diameter profile and the center thickness CT2 of the second lens on the optical axis satisfy: 2.37≤T2d1 / CT2≤5.

91.

16. The optical system according to any one of claims 11 to 15, characterized in that, The axial distance T12 between the second side surface of the first lens and the first side surface of the second lens, the effective half-aperture T2b1 between the optical center of the first side surface of the second lens and the left edge of the effective diameter profile, and the effective half-aperture T1b2 between the optical center of the second side surface of the first lens and the left edge of the effective diameter profile satisfy: 0.7mm <T12×(T2b1 / T1b2)<1.3mm。 17. The optical system according to any one of claims 11 to 15, characterized in that, The center thickness CT1 of the first lens on the optical axis, the center thickness CTR of the reflective polarizing element on the optical axis, the center thickness CTQ of the quarter-wave plate on the optical axis, and the combined focal length F1 of the first lens, the reflective polarizing element, and the quarter-wave plate satisfy: 0 < (CT1 + CTR + CTQ) / F1 < 0.

06.

18. The optical system according to any one of claims 11 to 15, characterized in that, The effective focal length f1 of the first lens and the effective focal length f3 of the third lens satisfy: -0.3 < (f1-f3) / (f1+f3) ≤ 0.

10.

19. The optical system according to any one of claims 11 to 15, characterized in that, The Abbe number V2 of the second lens, the effective half-aperture T2d1 from the optical center of the first side of the second lens to the right edge of the effective diameter profile, and the effective half-aperture T2a1 from the optical center of the first side of the second lens to the upper edge of the effective diameter profile satisfy: 42.9 <V2 / (T2d1 / T2a1)≤46.92。 20. The optical system according to any one of claims 11 to 15, characterized in that, The radius of curvature R6 of the second side surface of the third lens, the total effective focal length f of the optical system, and the maximum semi-FOV of the optical system satisfy: -3.

6. <R6 / (f×tan(Semi-FOV))≤-3.16。

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