Visual system

Abstract

The utility model discloses a visual system. The visual system comprises a lens cone, an optical element group and a spacer group, wherein the optical element group and the spacer group are arranged in the lens cone; the optical element group comprises a first element group with negative focal power, a second element group with positive focal power, a third element group and a fourth element group with positive focal power which are sequentially arranged from the first side to the second side along the optical axis; the first element group comprises a reflective polarizing element, a quarter-wave plate and a first lens; the second element group comprises a second lens; the third element group comprises a third lens; the fourth element group comprises a fourth lens; the spacer group includes a first spacer disposed on the second side of the first lens and in contact with the second side of the first lens; wherein the effective focal length FG1 of the first element group and the total effective focal length f of the visual system meet the following formula:-41lt; fG1 / flt; 18); and a center thickness CT1 of the first lens on the optical axis, a spacing distance T12 of the first lens and the second lens on the optical axis, and a maximum thickness CP1 of the first spacer satisfy: 1.5 lt; cT1 / (CP1 + T12) lt; and 4.5.

Description

Technical Field

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

[0002] With the proposal of the concept of the metaverse, the virtual reality technology and augmented reality technology of human-computer interaction have迎来了第二次发展的契机。目视系统作为人机交互的重要入口,在其中发挥着关键作用。目视系统主要分为采用非球面透镜的光学系统、采用菲涅尔透镜的光学系统、折反式光学系统三种,其中,折反式光学系统是目视系统自身的重大创新,并且为虚拟现实设备或增强现实设备的整机设计预留空间,已经成为研发的主流趋势。

[0003] The catadioptric optical system shortens the body length of the visual system by refracting the optical path, thereby shifting the center of gravity of the virtual reality device or augmented reality device backward and improving the user experience. However, the existing catadioptric optical systems usually use two lenses, which results in a relatively blurred image and poor imaging quality of the catadioptric optical system. Utility Model Content

[0004] This application provides a visual system that can at least solve or partially solve at least one problem or other problems existing in the prior art.

[0005] On the one hand, this application provides such a visual system, which includes a lens barrel and an optical element group and a spacer group disposed in the lens barrel. The optical element group includes a first element group with a negative optical power, a second element group with a positive optical power, a third element group, and a fourth element group with a positive optical power arranged in sequence along the optical axis from the first side to the second side. The first element group includes a reflective polarizing element, a quarter-wave plate, and a first lens. The second element group includes a second lens. The third element group includes a third lens. The fourth element group includes a fourth lens. The spacer group includes a first spacer, and the first spacer is disposed on the second side surface of the first lens and is in contact with the second side surface of the first lens. Wherein, the effective focal length FG1 of the first element group and the total effective focal length f of the visual system satisfy: -41 < FG1 / f < -18; the central thickness CT1 of the first lens on the optical axis, the spacing distance T12 between the first lens and the second lens on the optical axis, and the maximum thickness CP1 of the first spacer satisfy: 1.5 < CT1 / (CP1 + T12) < 4.5.

[0006] It should be noted that there is an unclear expression in the original text "迎来了第二次发展的契机" which is translated as "has ushered in an opportunity for a second development" tentatively. You may need to check and correct it according to the actual situation.According to an exemplary embodiment of the present application, the radius of curvature R3 of the first side surface of the second lens and the radius of curvature R4 of the second side surface of the second lens satisfy: -0.5 < R3 / R4 < 0; and the radius of curvature R3 of the first side surface of the second lens, the refractive index N2 of the second lens, and the outer diameter D1m of the second side surface of the first spacer satisfy: 1.8 < R3×N2 / D1m < 5.3.

[0007] According to an exemplary embodiment of the present application, the total effective focal length f of the visual system, the on-axis distance TD from the first side surface of the first lens to the second side surface of the fourth lens, and the maximum length L of the lens barrel along the optical axis direction satisfy: -26 < f / (L - TD) < -5.

[0008] According to an exemplary embodiment of the present application, 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: 0.5 < d0s / d0m < 1.

[0009] According to an exemplary embodiment of the present application, the spacer distance EP01 along the optical axis between the first side end surface of the lens barrel and the first side surface of the first spacer, 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 central thickness CT1 of the first lens on the optical axis satisfy: 1 < EP01 / (CTR + CTQ + CT1) < 3.5.

[0010] According to an exemplary embodiment of the present application, the inner diameter d0s of the first side end surface of the lens barrel, the inner diameter d0m of the second side end surface of the lens barrel, the effective full aperture DT11 of the first side surface of the first lens, and the effective full aperture DT42 of the second side surface of the fourth lens satisfy: 0.5 < (d0m - DT42) / (d0s - DT11) < 1.5.

[0011] According to an exemplary embodiment of the present application, the spacer group further includes a second spacer, and the second spacer is placed on the second side surface of the second lens and is in contact with the second side surface of the second lens. Among them, the effective focal length FG2 of the second lens group, the refractive index N2 of the second lens, and the inner diameter d2s of the first side surface of the second spacer satisfy: 3 < FG2 / d2s×N2 < 6.

[0012] According to an exemplary embodiment of the present application, the spacer group further includes a second spacer, and the second spacer is placed on the second side surface of the second lens and is in contact with the second side surface of the second lens. Among them, the central thickness CT2 of the second lens on the optical axis, the spacer distance EP12 along the optical axis between the second side surface of the first spacer and the first side surface of the second spacer, and the maximum thickness CP2 of the second spacer satisfy: 1 < CT2 / (EP12 + CP2) < 2.

[0013] According to an exemplary embodiment of the present application, the spacer group further includes a second spacer, and the second spacer is placed on the second side surface of the second lens and contacts the second side surface of the second lens. Wherein, the inner diameter d1m of the second side surface of the first spacer, the outer diameter D1m of the second side surface of the first spacer, the inner diameter d2m of the second side surface of the second spacer, and the outer diameter D2m of the second side surface of the second spacer satisfy: 0 < (D2m - d2m) / (D1m - d1m) < 1.

[0014] According to an exemplary embodiment of the present application, the spacer group further includes a second spacer and a third spacer. The second spacer is placed on the second side surface of the second lens and contacts the second side surface of the second lens. The third spacer is placed on the second side surface of the third lens and contacts the second side surface of the third lens. Wherein, the central thickness CT3 of the third lens on the optical axis and the interval distance EP23 along the optical axis between the second side surface of the second spacer and the first side surface of the third spacer satisfy: 0 < EP23 / CT3 < 3; and the maximum thickness CP3 of the third spacer and the interval distance T34 between the third lens and the fourth lens on the optical axis satisfy: 0 < CP3 / T34 < 2.

[0015] According to an exemplary embodiment of the present application, the spacer group further includes a third spacer, and the third spacer is placed on the second side surface of the third lens and contacts the second side surface of the third lens. Wherein, the central thickness CT4 of the fourth lens on the optical axis, the inner diameter d3s of the first side surface of the third spacer, and the outer diameter D3m of the second side surface of the third spacer satisfy: 1 < CT4 / (D3m - d3s) < 2.5.

[0016] According to an exemplary embodiment of the present application, the Abbe number of any one of the first lens to the fourth lens is less than 25.

[0017] According to an exemplary embodiment of the present application, the quarter-wave plate is arranged on the first side surface of the first lens, and the reflective polarizing element is arranged on the first side surface of the quarter-wave plate.

[0018] The visual system provided by the present application is configured as a catadioptric optical system with four lenses. Reasonably configuring the optical power of each lens is beneficial to improving the imaging quality of the visual system. And by making the visual system satisfy "-41 < FG1 / f < -18", the exit angle of the light rays exiting from the first element group can be restricted; at the same time, by coordinating and controlling the relationship between the central thickness of the first lens on the optical axis, the interval distance between the first lens and the second lens on the optical axis, and the maximum thickness of the first spacer, the maximum thickness of the first spacer and the interval distance between the first lens and the second lens can be restricted within a certain range, thereby restricting the overall size of the visual system, improving the portability of the visual system, and also ensuring an appropriate thickness ratio between the center and the edge of the first lens, and improving the processing formability of the first lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings, in which:

[0020] Figure 1 A schematic diagram of parameter annotation of a visual system according to the present application is shown;

[0021] Figure 2 A schematic diagram of the structure of a visual system according to Example 1 of the present application is shown;

[0022] Figure 3 A schematic diagram of the structure of a visual system according to Embodiment 2 of the present application is shown;

[0023] Figure 4 A schematic structural diagram of a visual system according to Embodiment 3 of the present application is shown;

[0024] FIG. 5A to FIG. 5C The axial chromatic aberration curve, the astigmatism curve and the distortion curve of the visual system according to Embodiment 1, 2 or 3 of the present application are respectively shown;

[0025] Figure 6 A schematic diagram of the structure of a visual system according to Embodiment 4 of the present application is shown;

[0026] Figure 7 A schematic diagram of the structure of a visual system according to Embodiment 5 of the present application is shown;

[0027] Figure 8 A schematic diagram of the structure of a visual system according to Example 6 of the present application is shown;

[0028] 9A to 9C The axial chromatic aberration curve, the astigmatism curve and the distortion curve of the visual system according to Embodiment 4, 5 or 6 of the present application are respectively shown;

[0029] Fig.10 A schematic diagram of the structure of a visual system according to Embodiment 7 of the present application is shown;

[0030] Fig.11 A schematic diagram of the structure of a visual system according to Example 8 of the present application is shown;

[0031] Fig.12 A schematic diagram of the structure of a visual system according to Embodiment 9 of the present application is shown; and

[0032] FIG. 13A to FIG. 13C The axial chromatic aberration curve, the astigmatism curve and the distortion curve of the visual system according to Embodiment 7, 8 or 9 of the present application are respectively shown;

[0033] Fig.14 The Modulation Transfer Function (MTF) curve is shown when the visual system satisfies FG1 / f=-25.4, CT1 / (CP1+T12)=1.82;

[0034] Fig.15 The modulation transfer function curve when the visual system satisfies FG1 / f=-19.1, CT1 / (CP1+T12)=3.68 is shown;

[0035] Fig.16 The modulation transfer function curve when the visual system satisfies FG1 / f=-60, CT1 / (CP1+T12)=0.02 is shown; and

[0036] Fig.17 The modulation transfer function curve is shown when the visual system satisfies FG1 / f=2, CT1 / (CP1+T12)=14. DETAILED DESCRIPTION

[0037] In order to better understand the present application, a more detailed description will be made of various aspects of the present application with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application, and do not limit the scope of the present application in any way. Throughout the specification, the same figure numerals refer to the same elements.

[0038] It should be noted that in this specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teaching of the present application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0039] In the 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 shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0040] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial 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.

[0041] It should also be understood that the terms "include", "comprising", "having", "including" and / or "comprising", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when describing embodiments of the present application, the term "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0042] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as those commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having the same meaning as their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0043] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0044] The features, principles and other aspects of the present application are described in detail below.

[0045] refer to Figures 2 to 4 , Figures 6 to 8 as well as Figures 10 to 12 In a first aspect of the present application, a visual system is provided, which may include an optical element group, and the optical element group may include a first element group, a second element group, a third element group, and a fourth element group arranged in sequence from a first side to a second side along an optical axis. Among the first element group to the fourth element group, any two adjacent element groups may have a spacing distance.

[0046] In an exemplary embodiment, the first element group may have a negative optical power. The second element group may have a positive optical power. The fourth element group may have a positive optical power. Reasonable configuration of the optical power of each element group is conducive to improving the imaging quality of the visual system.

[0047] In an exemplary embodiment, the third element group may have no optical power. Alternatively, the third element group may have positive optical power.

[0048] In an exemplary embodiment, the first element group may include a reflective polarizing element, a quarter wave plate, and a first lens, and the reflective polarizing element, the quarter wave plate, and the first lens are sequentially arranged from the first side to the second side along the optical axis.

[0049] In example embodiments, the second element group may include a second lens.

[0050] In example embodiments, the third element group may include a third lens.

[0051] In example embodiments, the fourth element group may include a fourth lens.

[0052] In an exemplary embodiment, the Abbe number of any one of the first to fourth lenses may be less than 25. Reasonable configuration of the Abbe numbers of the first, second, third and fourth lenses is conducive to correcting the chromatic aberration of the visual system and improving the performance of the visual system.

[0053] In an exemplary embodiment, the visual system may further include a spacer group. The spacer group may include one or more of a first spacer, a second spacer, and a third spacer. The first spacer may be placed on the second side of the first lens and at least partially contact the second side of the first lens. The second spacer may be placed on the second side of the second lens and at least partially contact the second side of the second lens. The third spacer may be placed on the second side of the third lens and at least partially contact the second side of the third lens. Reasonable use of spacers can effectively avoid stray light risks, reduce interference with image quality, and thereby improve the imaging quality of the visual system.

[0054] In an exemplary embodiment, the visual system may further include a lens barrel. The optical element group and the spacer group may be placed in the lens barrel. The lens barrel may include a first side end surface, a second side end surface, an outer annular surface, and an inner annular surface, wherein the end surface of the lens barrel closest to the first side is the first side end surface of the lens barrel, and the end surface of the lens barrel closest to the second side is the second side end surface of the lens barrel; in a direction perpendicular to the optical axis, the surface of the lens barrel farthest from the optical axis is the outer annular surface, and the surface of the lens barrel closest to the optical axis is the inner annular surface.

[0055] In an exemplary embodiment, the first side may be the human eye side, and the second side may be the display screen side. Accordingly, the first side of each element (reflective polarizing element, quarter wave plate, first lens, second lens, third lens, fourth lens) may be referred to as the side near the human eye, and the second side may be referred to as the side near the screen.

[0056] In an exemplary embodiment, a quarter wave plate may be disposed on the first side of the first lens. A reflective polarizing element may be disposed on the first side of the quarter wave plate. By providing the reflective polarizing element and the quarter wave plate, it is beneficial to increase the total length of the light path refraction of the visual system, so that the visual system has a larger field of view as much as possible while its total effective focal length meets the requirements, thereby improving the visual experience of the user, and shortening the length of the body of the visual system, which is beneficial to miniaturization of the visual system and the electronic device including the visual system.

[0057] In an exemplary embodiment, the reflective polarizing element and the quarter wave plate are laminated to form a film layer, and the laminated film layer is attached to the first side surface of the first lens. By laminating the reflective polarizing element and the quarter wave plate together to form a film layer, the number of attached surfaces of the film layer can be reduced, and the attachment yield of the film layer can be improved.

[0058] In an exemplary embodiment, the first side surface of the first lens can be configured as a plane, and a film layer formed by laminating a reflective polarizing element and a quarter wave plate is attached to the first side surface of the first lens. Adopting a planar laminating method to attach the composite film layer to a plane is conducive to improving the stability of the film layer after attachment, thereby improving the edge field performance of the visual system.

[0059] In an exemplary embodiment, the visual system may further include a partial reflective layer, which may be attached to the second side surface of the fourth lens. The partial reflective layer has a semi-transmissive and semi-reflective effect on light. By providing a partial reflective layer on the second side surface of the fourth lens, and combining a reflective polarizing element and a quarter wave plate, the light can be refracted multiple times, effectively reducing the length of the main body of the visual system.

[0060] In an exemplary embodiment, the visual system may further include an aperture, which may be disposed between the first side and the first lens. The image light on the display screen is refracted and reflected multiple times by the fourth lens, the third lens, the second lens, the first lens, the quarter wave plate, the reflective polarizing element, the partial reflective layer, etc., and is finally projected to the user's eyes.

[0061] In an exemplary embodiment, an image surface may be provided on the second side of the visual system, and a display screen may be provided on the image surface. The image light from the display screen sequentially passes through the fourth lens, the third lens, the second lens, the first lens, and the quarter wave plate to reach the reflective polarizing element, and then reflects at the reflective polarizing element to form a first reflected image light. The first reflected image light passes through the quarter wave plate, the first lens, the second lens, the third lens, the fourth lens and reaches the partial reflective layer located on the second side of the fourth lens, and then reflects at the partial reflective layer to form a second reflected image light. The second reflected image light sequentially passes through the fourth lens, the third lens, the second lens, the first lens, the quarter wave plate, the reflective polarizing element to the aperture and is finally projected into the user's eyes. The visual 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 visual system.

[0062] In an exemplary embodiment, the effective focal length FG1 of the first element group and the total effective focal length f of the visual system may satisfy: -41 < FG1 / f < -18; and the central thickness CT1 of the first lens on the optical axis, the spacing distance T12 between the first lens and the second lens on the optical axis, and the maximum thickness CP1 of the first spacer may satisfy: 1.5 < CT1 / (CP1 + T12) < 4.5. By controlling the visual system to satisfy "-41 < FG1 / f < -18", the exit angle of the light rays exiting from the first element group can be restricted; at the same time, by coordinating the control of the relationship between the central thickness of the first lens on the optical axis, the spacing distance between the first lens and the second lens on the optical axis, and the maximum thickness of the first spacer, the maximum thickness of the first spacer and the spacing distance between the first lens and the second lens can be restricted within a certain range, thereby limiting the overall size of the visual system, improving the portability of the visual system, and ensuring an appropriate thickness ratio between the center and the edge of the first lens, improving the processability of the first lens during processing, and avoiding extreme forming processes.

[0063] The following will describe the imaging quality of the visual system in conjunction with Fig.14 , Fig.15 , Fig.16 and Fig.17 . Fig.14 is the modulation transfer function curve when the visual system satisfies FG1 / f = -25.4 and CT1 / (CP1 + T12) = 1.82; Fig.15 is the modulation transfer function curve when the visual system satisfies FG1 / f = -19.1 and CT1 / (CP1 + T12) = 3.68; Fig.16 is the modulation transfer function curve when the visual system satisfies FG1 / f = -60 and CT1 / (CP1 + T12) = 0.02; Fig.17 is the modulation transfer function curve when the visual system satisfies FG1 / f = 2 and CT1 / (CP1 + T12) = 14.

[0064] From Fig.14 and Fig.15 , it can be seen that at the same defocus position, the coincidence degree of the optical modulation function values of different fields of view is relatively good. From Fig.16 and Fig.17 , it can be seen that at the same defocus position, the optical modulation function values of different fields of view will have a large deviation and the coincidence degree is poor. It can be seen that by making the visual system satisfy "-41 < FG1 / f < -18, 1.5 < CT1 / (CP1 + T12) < 4.5", it helps to improve the imaging quality of the visual system.

[0065] In an exemplary embodiment, the radius of curvature R3 of the first side surface of the second lens and the radius of curvature R4 of the second side surface of the second lens may satisfy: -0.5 < R3 / R4 < 0; and the radius of curvature R3 of the first side surface of the second lens, the refractive index N2 of the second lens, and the outer diameter D1m of the second side surface of the first spacer may satisfy: 1.8 < R3×N2 / D1m < 5.3. By controlling the ratio of the radius of curvature of the first side surface and the second side surface of the second lens, the field curvature contribution of the second lens can be constrained within a reasonable range, reducing the optical sensitivity of the first side surface and the second side surface of the second lens, and helping to improve the spherical aberration and astigmatism of the visual system; at the same time, by coordinating the relationship between the radius of curvature of the first side surface of the second lens, the refractive index of the second lens, and the outer diameter of the second side surface of the first spacer, the reflected stray light of the visual system can be reduced, and the imaging quality of the visual system can be improved.

[0066] In an exemplary embodiment, the total effective focal length f of the visual system, the on-axis distance TD from the first side surface of the first lens to the second side surface of the fourth lens, and the maximum length L of the lens barrel along the optical axis direction may satisfy: -26 < f / (L - TD) < -5. By reasonably configuring the relationship between the total effective focal length of the visual system, the on-axis distance from the first side surface of the first lens to the second side surface of the fourth lens, and the maximum length of the lens barrel along the optical axis direction, the total effective focal length of the visual system can be constrained within an appropriate range, thereby constraining the field of view angle of the visual system and ensuring that the visual system meets the characteristics of a large field of view angle of an electronic device (such as a virtual reality (VR) lens); at the same time, the on-axis distance from the first side surface of the first lens to the second side surface of the fourth lens and the maximum length of the lens barrel along the optical axis direction can also be restricted. Under the condition of ensuring the machinability of the lens barrel, the outer dimension of the lens barrel can be made as small as possible, thereby reducing the overall dimension of the visual system.

[0067] In an exemplary embodiment, 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 may satisfy: 0.5 < d0s / d0m < 1. By controlling the ratio of the inner diameters of the first side end surface and the second side end surface of the lens barrel, the overall dimension of the visual system can be effectively constrained, facilitating the later matching of the visual system with the module; at the same time, under the condition of ensuring the machinability of the lens barrel, the dimension of the lens barrel can be made as small as possible, thereby reducing the overall dimension of the visual system.

[0068] In an exemplary embodiment, the spacing distance EP01 along the optical axis between the first side end face of the lens barrel and the first side face of the first spacer, 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 central thickness CT1 of the first lens on the optical axis may satisfy: 1 < EP01 / (CTR + CTQ + CT1) < 3.5. By controlling the ratio of the spacing distance along the optical axis between the first side end face of the lens barrel and the first side face of the first spacer to the sum of the central thicknesses of the reflective polarizing element, the quarter-wave plate, and the first lens, a reasonable thickness ratio between the edge and the center of the first lens can be ensured, improving the processing formability of the first lens and avoiding extreme forming processes.

[0069] In an exemplary embodiment, the inner diameter d0s of the first side end face of the lens barrel, the inner diameter d0m of the second side end face of the lens barrel, the effective full aperture DT11 of the first side face of the first lens, and the effective full aperture DT42 of the second side face of the fourth lens may satisfy: 0.5 < (d0m - DT42) / (d0s - DT11) < 1.5. By reasonably configuring the relationship between the inner diameter of the first side end face of the lens barrel, the inner diameter of the second side end face of the lens barrel, the effective full aperture of the first side face of the first lens, and the effective full aperture of the second side face of the fourth lens, the inner diameters of the first side end face and the second side end face of the lens barrel can be constrained within an appropriate range, thereby effectively constraining the overall size of the visual system and facilitating the later matching of the visual system with the module; at the same time, the effective full apertures of the first side face of the first lens and the second side face of the fourth lens can also be restricted. Under the condition of ensuring that the first lens and the fourth lens meet the requirements of the visual system and the processability of the lenses, the size of the lens barrel can be made as small as possible, thereby reducing the overall size of the visual system.

[0070] In an exemplary embodiment, the effective focal length FG2 of the second lens group, the refractive index N2 of the second lens, and the inner diameter d2s of the first side face of the second spacer may satisfy: 3 < FG2 / d2s × N2 < 6. By reasonably configuring the relationship between the effective focal length of the second lens group, the refractive index of the second lens, and the inner diameter of the first side face of the second spacer, the second lens group can have an appropriate optical power, which is beneficial to optimizing the light path of the visual system; at the same time, the inner diameter of the first side face of the second spacer can also be restricted to ensure that the second spacer can block non-imaging light, effectively improving the stray light phenomenon of the visual system and enhancing the imaging quality of the visual system.

[0071] In an exemplary embodiment, the central thickness CT2 of the second lens on the optical axis, the spacing distance EP12 along the optical axis between the second side surface of the first spacer and the first side surface of the second spacer, and the maximum thickness CP2 of the second spacer may satisfy: 1 < CT2 / (EP12 + CP2) < 2. By reasonably configuring the relationship among the central thickness of the second lens on the optical axis, the spacing distance along the optical axis between the second side surface of the first spacer and the first side surface of the second spacer, and the maximum thickness of the second spacer, the central thickness of the second lens and the maximum thickness of the second spacer can be constrained within an appropriate range, which is beneficial to the processing and forming of the second lens and the second spacer. At the same time, the spacing distance along the optical axis between the second side surface of the first spacer and the first side surface of the second spacer can also be restricted, which is beneficial to realizing the thinness and lightness of the visual system.

[0072] In an exemplary embodiment, the inner diameter d1m of the second side surface of the first spacer, the outer diameter D1m of the second side surface of the first spacer, the inner diameter d2m of the second side surface of the second spacer, and the outer diameter D2m of the second side surface of the second spacer may satisfy: 0 < (D2m - d2m) / (D1m - d1m) < 1. By reasonably configuring the inner and outer diameters of the second side surface of the first spacer and the inner and outer diameters of the second side surface of the second spacer, the light input amount of the visual system can be constrained, and the light can be utilized to participate in imaging with the highest efficiency. At the same time, the first spacer and the second spacer can be used to better change the reflection route of the redundant light, reduce the generation of stray light, and improve the imaging clarity of the visual system.

[0073] In an exemplary embodiment, the central thickness CT3 of the third lens on the optical axis and the spacing distance EP23 along the optical axis between the second side surface of the second spacer and the first side surface of the third spacer may satisfy: 0 < EP23 / CT3 < 3; and the maximum thickness CP3 of the third spacer and the spacing distance T34 between the third lens and the fourth lens on the optical axis may satisfy: 0 < CP3 / T34 < 2. By controlling the above conditional expressions, the thicknesses of the components inside the lens barrel can be reasonably distributed, which is beneficial to the assembly of the visual system. At the same time, the spacing distance along the optical axis between the second side surface of the second spacer and the first side surface of the third spacer can be constrained within a certain range, so that the third lens has an appropriate edge thickness, reducing the processing and assembly difficulty of the third lens and improving the assembly stability of the visual system.

[0074] In an exemplary embodiment, the central thickness CT4 of the fourth lens on the optical axis, the inner diameter d3s of the first side surface of the third spacer, and the outer diameter D3m of the second side surface of the third spacer may satisfy: 1 < CT4 / (D3m - d3s) < 2.5. By reasonably configuring the relationship among the central thickness of the fourth lens on the optical axis, the inner diameter of the first side surface of the third spacer, and the outer diameter of the second side surface of the third spacer, the fourth lens can have a relatively large central thickness, increasing the optical path turning length of the visual system, thereby reducing the size of the electronic device including the visual system; at the same time, the inner diameter of the first side surface of the third spacer and the outer diameter of the second side surface of the third spacer can be restricted, effectively controlling the light input amount of the visual system and reducing the overall size of the visual system, which is beneficial to achieving the portability of the visual system.

[0075] The visual system according to the above embodiment of the present application may employ multiple lenses, such as the four lenses described above. By reasonably allocating the parameters of the reflective polarizing element, the quarter-wave plate, each lens, the lens barrel, and each spacer, the body length of the visual system can be reduced, and the processability, assembly stability, and imaging quality of the visual system can be improved. The visual system configured as above has the characteristics of miniaturization, a large field of view angle, and good imaging quality, and can well meet the usage requirements of various portable electronic products in the projection scenario. Moreover, the center of gravity of the visual system and the electronic device including the visual system moves backward, improving the user's wearing experience.

[0076] In an embodiment of the present application, at least one of the surfaces of each of the first lens to the fourth 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 curvature radius characteristics and has the advantages of improving distortion aberration and improving astigmatism aberration. After using an aspherical lens, the aberration that appears during imaging can be eliminated as much as possible, thereby improving the imaging quality.

[0077] 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 visual system can be changed to obtain the various results and advantages described in this specification.

[0078] The second aspect of the present application provides such a visual system, which may include a lens barrel and an optical element group placed in the lens barrel. The optical element group may include a first element group with negative optical power, a second element group with positive optical power, a third element group and a fourth element group with positive optical power arranged in sequence from the first side to the second side along the optical axis. The first element group may include a reflective polarizing element, a quarter wave plate and a first lens. The second element group may include a second lens. The third element group may include a third lens. The fourth element group may include a fourth lens.

[0079] Among them, the inner diameter d0s of the first side end surface of the lens barrel, the inner diameter d0m of the second side end surface of the lens barrel, the effective full aperture DT11 of the first side surface of the first lens, and the effective full aperture DT42 of the second side surface of the fourth lens can satisfy: 0.5<(d0m-DT42) / (d0s-DT11)<1.5. The visual system provided in the present application is configured as a catadioptric optical system with four lenses, and the optical focal length of each lens is reasonably configured, which is conducive to improving the imaging quality of the visual system. Furthermore, by controlling the relationship between the inner diameter of the first side end face of the lens barrel, the inner diameter of the second side end face of the lens barrel, the effective full aperture of the first side face of the first lens, and the effective full aperture of the second side face of the fourth lens, the inner diameters of the first side end face and the second side end face of the lens barrel can be constrained within an appropriate range, thereby effectively constraining the overall size of the visual system and facilitating the later matching of the visual system with the module; at the same time, the effective full apertures of the first side face of the first lens and the second side face of the fourth lens can also be restricted, so that the size of the lens barrel can be as small as possible while ensuring that the first lens and the fourth lens meet the requirements of the visual system and the processability of the lenses, thereby reducing the overall size of the visual system.

[0080] The third aspect of the present application provides such a visual system, which may include a lens barrel and an optical element group and a spacer group placed in the lens barrel. The optical element group may include a first element group with negative optical power, a second element group with positive optical power, a third element group and a fourth element group with positive optical power arranged in sequence from the first side to the second side along the optical axis. The first element group may include a reflective polarizing element, a quarter wave plate and a first lens. The second element group may include a second lens. The third element group may include a third lens. The fourth element group may include a fourth lens. The spacer group may include a first spacer, and the first spacer is placed on the second side of the first lens and contacts the second side of the first lens.

[0081] Among them, the radius of curvature R3 of the first side of the second lens and the radius of curvature R4 of the second side of the second lens may satisfy: -0.5 < R3 / R4 < 0; and the radius of curvature R3 of the first side of the second lens, the refractive index N2 of the second lens, and the outer diameter D1m of the second side of the first spacer may satisfy: 1.8 < R3×N2 / D1m < 5.3. The visual system provided in this application is configured as a catadioptric optical system with four lenses. Reasonably configuring the optical power of each lens is beneficial to improving the imaging quality of the visual system. And by controlling the ratio of the radius of curvature of the first side and the second side of the second lens, the field curvature contribution of the second lens can be constrained within a reasonable range, reducing the optical sensitivity of the first side and the second side of the second lens, and improving the spherical aberration and astigmatism of the visual system; at the same time, by coordinating and restricting the relationship between the radius of curvature of the first side of the second lens, the refractive index of the second lens, and the outer diameter of the second side of the first spacer, the reflected stray light of the visual system can be reduced, and the imaging quality of the visual system can be improved.

[0082] Specific embodiments of the visual system applicable to the above embodiments will be further described below with reference to the accompanying drawings.

[0083] Example 1

[0084] The following refers to Figure 2 Describe the visual system according to Embodiment 1 of this application.

[0085] As Figure 2 shown, the visual system may include a lens barrel and an optical element group and a spacer group disposed in the lens barrel.

[0086] The optical element group may include a first element group, a second element group, a third element group, and a fourth element group arranged in sequence along the optical axis from the first side to the second side. The first element group may include a reflective polarizing element RP, a quarter-wave plate QWP, and a first lens E1. The second element group may include a second lens E2. The third element group may include a third lens E3. The fourth element group may include a fourth lens E4. A diaphragm STO (not shown) may also be provided between the first side and the first lens E1. A partial reflection layer BS (not shown) may also be provided on the second side of the fourth lens E4. The spacer group may include a first spacer P1 and a second spacer P2. The first side of each element (the first lens E1, the second lens E2, the third lens E3, the fourth lens E4) is referred to as the side close to the human eye, and the second side is referred to as the side close to the screen.

[0087] The first lens E1 has negative focal power, and its side S1 near the human eye is a plane, and its side S2 near the screen is a concave surface. The second lens E2 has positive focal power, and its side S3 near the human eye is a convex surface, and its side S4 near the screen is a convex surface. The side S5 near the human eye of the third lens E3 is a plane, and the side S6 near the screen is a plane. The fourth lens E4 has positive focal power, and its side S7 near the human eye is a convex surface, and the side S8 near the screen is a convex surface. The quarter-wave plate QWP is attached to the side S1 near the human eye of the first lens E1. The reflective polarizing element RP is attached to the side surface of the quarter-wave plate QWP away from the first lens E1. The partial reflection layer BS is attached to the side S8 near the screen of the fourth lens E4.

[0088] In this example, an image surface IMG may be provided on the second side of the visual system, and the image surface IMG may be provided with a display screen, for example. After the image light from the image surface IMG passes through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter wave plate QWP in sequence and reaches the reflective polarizing element RP, a first reflection occurs at the reflective polarizing element RP. After the light reflected for the first time passes through the quarter wave plate QWP, the first lens E1, the second lens E2, the third lens E3, the fourth lens E4 and reaches the partial reflection layer BS located on the near-screen side S8 of the fourth lens E4, a second reflection occurs at the partial reflection layer BS. The light reflected for the second time passes through the fourth lens E4, 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 STO in sequence and is finally projected into the eyes of the user. For example, the light of the visual system after two reflections is finally projected into the eyes of the user.

[0089] Table 1 shows the basic parameters of the visual system of Example 1, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm). The image light from the image surface IMG passes through the components in the order of sequence number 27 to sequence number 1 and is finally projected into the human eye.

[0090]

[0091] Table 1

[0092] In this embodiment, the screen-side surface S2 of the first lens E1, the eye-side surface S3 and the screen-side surface S4 of the second lens E2, and the eye-side surface S7 and the screen-side surface S8 of the fourth lens E4 are all aspherical surfaces, and the surface shape x of each aspherical lens can be defined by, but not limited to, the following aspherical surface formula:

[0093]

[0094] Wherein, x is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of h along the optical axis; c is the paraxial curvature of the aspheric surface, c=1 / R (i.e., the paraxial curvature c is the reciprocal of the curvature radius R in Table 1 above); k is the cone coefficient; Ai is the correction coefficient of the i-th order of the aspheric surface. Table 2 shows the high-order coefficients A4, A6, A8 and A10 that can be used for each aspheric surface S2-S4, S7-S8 in Example 1.

[0095] Face number A4 A6 A8 A10 S2 3.2582E-06 1.1300E-08 3.2929E-14 -6.3588E-14 S3 -2.0792E-06 2.5741E-09 -5.0939E-13 0.0000E+00 S4 -2.7709E-06 -7.0294E-10 1.4658E-12 3.4280E-14 S7 -3.3756E-06 9.3362E-10 -5.0484E-13 0.0000E+00 S8 -3.6178E-07 -1.1542E-09 -2.2313E-12 -6.5574E-16

[0096] Table 2

[0097] Example 2

[0098] The following reference Figure 3 Describe the visual system according to Example 2 of the present application.

[0099] like Figure 3 As shown, the visual system may include a lens barrel and an optical element group and a spacer group placed in the lens barrel. The optical element group may include a first element group, a second element group, a third element group and a fourth element group arranged in sequence from the first side to the second side along the optical axis. The first element group may include a reflective polarizing element RP, a quarter wave plate QWP and a first lens E1. The second element group may include a second lens E2. The third element group may include a third lens E3. The fourth element group may include a fourth lens E4. A stop STO (not shown) may also be provided between the first side and the first lens E1. The second side of the fourth lens E4 may also be provided with a partial reflection layer BS (not shown). The spacer group may include a first spacer P1 and a second spacer P2.

[0100] The structure of the optical element group of this embodiment is the same as that of the optical element group of Embodiment 1, that is, the basic parameter table of the visual system of this embodiment is the same as Table 1, and the aspheric coefficient table is the same as Table 2. The difference between this embodiment and Embodiment 1 is that the structural dimensions of at least some components in the lens barrel and the spacer group are different.

[0101] Example 3

[0102] The following reference Figure 4 Describe the visual system according to Example 3 of the present application.

[0103] like Figure 4As shown, the visual system may include a lens barrel and an optical element group and a spacer group placed in the lens barrel. The optical element group may include a first element group, a second element group, a third element group and a fourth element group arranged in sequence from the first side to the second side along the optical axis. The first element group may include a reflective polarizing element RP, a quarter wave plate QWP and a first lens E1. The second element group may include a second lens E2. The third element group may include a third lens E3. The fourth element group may include a fourth lens E4. A stop STO (not shown) may also be provided between the first side and the first lens E1. The second side of the fourth lens E4 may also be provided with a partial reflection layer BS (not shown). The spacer group may include a first spacer P1 and a second spacer P2.

[0104] The structure of the optical element group of this embodiment is the same as that of the optical element group of Embodiment 1, that is, the basic parameter table of the visual system of this embodiment is the same as Table 1, and the aspheric coefficient table is the same as Table 2. The difference between this embodiment and Embodiment 1 is that the structural dimensions of at least some components in the lens barrel and the spacer group are different.

[0105] Figure 5A The axial chromatic aberration curve of the visual system of Example 1, 2 or 3 is shown, which indicates the deviation of the focal point of light of different wavelengths after passing through the visual system. Figure 5B The astigmatism curves of the visual systems of Examples 1, 2 or 3 are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field angles. Figure 5C The distortion curve of the visual system of Embodiment 1, 2 or 3 is shown, which indicates the distortion magnitude value corresponding to different field angles. FIG. 5A to FIG. 5C It can be seen that the visual system provided in Example 1, 2 or 3 can achieve good imaging quality.

[0106] Example 4

[0107] The following reference Figure 6 Describe the visual system according to Example 4 of the present application.

[0108] like Figure 6 As shown, the visual system may include a lens barrel and an optical element group and a spacer group placed in the lens barrel.

[0109] The optical element group may include a first element group, a second element group, a third element group and a fourth element group arranged in sequence from the first side to the second side along the optical axis. The first element group may include a reflective polarizing element RP, a quarter wave plate QWP and a first lens E1. The second element group may include a second lens E2. The third element group may include a third lens E3. The fourth element group may include a fourth lens E4. A stop STO (not shown) may also be provided between the first side and the first lens E1. A partial reflection layer BS (not shown) may also be provided on the second side of the fourth lens E4. The spacer group may include a first spacer P1, a second spacer P2 and a third spacer P3. The first side of each element (the first lens E1, the second lens E2, the third lens E3, the fourth lens E4) is referred to as a side near the human eye, and the second side is referred to as a side near the screen.

[0110] The first lens E1 has negative focal power, and its side S1 near the human eye is a plane, and its side S2 near the screen is a concave surface. The second lens E2 has positive focal power, and its side S3 near the human eye is a convex surface, and its side S4 near the screen is a convex surface. The side S5 near the human eye of the third lens E3 is a plane, and the side S6 near the screen is a plane. The fourth lens E4 has positive focal power, and its side S7 near the human eye is a convex surface, and the side S8 near the screen is a convex surface. The quarter-wave plate QWP is attached to the side S1 near the human eye of the first lens E1. The reflective polarizing element RP is attached to the side surface of the quarter-wave plate QWP away from the first lens E1. The partial reflection layer BS is attached to the side S8 near the screen of the fourth lens E4.

[0111] In this example, an image surface IMG may be provided on the second side of the visual system, and the image surface IMG may be provided with a display screen, for example. After the image light from the image surface IMG passes through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter wave plate QWP in sequence and reaches the reflective polarizing element RP, a first reflection occurs at the reflective polarizing element RP. After the light reflected for the first time passes through the quarter wave plate QWP, the first lens E1, the second lens E2, the third lens E3, the fourth lens E4 and reaches the partial reflection layer BS located on the near-screen side S8 of the fourth lens E4, a second reflection occurs at the partial reflection layer BS. The light reflected for the second time passes through the fourth lens E4, 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 STO in sequence and is finally projected into the eyes of the user. For example, the light of the visual system after two reflections is finally projected into the eyes of the user.

[0112] Table 3 shows the basic parameters of the visual system of Example 4, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm). The image light from the image surface IMG passes through the components in the order of sequence number 27 to sequence number 1 and is finally projected into the human eye.

[0113]

[0114]

[0115] Table 3

[0116] In this embodiment, the screen-side surface S2 of the first lens E1, the eye-side surface S3 and the screen-side surface S4 of the second lens E2, and the eye-side surface S7 and the screen-side surface S8 of the fourth lens E4 are all aspherical surfaces. Table 4 lists the high-order coefficients A4, A6, A8 and A10 of the aspherical surfaces S2-S4, S7-S8 that can be used in Embodiment 4.

[0117] Face number A4 A6 A8 A10 S2 2.7214E-06 1.2492E-08 2.5851E-12 -4.9085E-14 S3 -2.0395E-06 2.0695E-09 -1.3406E-12 0.0000E+00 S4 -2.9720E-06 -5.6253E-10 1.2213E-12 3.5077E-14 S7 -3.1924E-06 9.7281E-10 -4.3907E-13 0.0000E+00 S8 2.0437E-07 -8.7821E-10 -2.7061E-12 -2.1980E-15

[0118] Table 4

[0119] Example 5

[0120] The following reference Figure 7 Describe the visual system according to Example 5 of the present application.

[0121] like Figure 7 As shown, the visual system may include a lens barrel and an optical element group and a spacer group placed in the lens barrel. The optical element group may include a first element group, a second element group, a third element group and a fourth element group arranged in sequence from the first side to the second side along the optical axis. The first element group may include a reflective polarizing element RP, a quarter wave plate QWP and a first lens E1. The second element group may include a second lens E2. The third element group may include a third lens E3. The fourth element group may include a fourth lens E4. A stop STO (not shown) may also be provided between the first side and the first lens E1. The second side of the fourth lens E4 may also be provided with a partial reflection layer BS (not shown). The spacer group may include a first spacer P1, a second spacer P2 and a third spacer P3.

[0122] The structure of the optical element group of this embodiment is the same as that of the optical element group of Embodiment 4, that is, the basic parameter table of the visual system of this embodiment is the same as Table 3, and the aspheric coefficient table is the same as Table 4. The difference between this embodiment and Embodiment 4 is that the structural dimensions of at least some components in the lens barrel and the spacer group are different.

[0123] Example 6

[0124] The following reference Figure 8 Describe the visual system according to Example 6 of the present application.

[0125] like Figure 8 As shown, the visual system may include a lens barrel and an optical element group and a spacer group placed in the lens barrel. The optical element group may include a first element group, a second element group, a third element group and a fourth element group arranged in sequence from the first side to the second side along the optical axis. The first element group may include a reflective polarizing element RP, a quarter wave plate QWP and a first lens E1. The second element group may include a second lens E2. The third element group may include a third lens E3. The fourth element group may include a fourth lens E4. A stop STO (not shown) may also be provided between the first side and the first lens E1. The second side of the fourth lens E4 may also be provided with a partial reflection layer BS (not shown). The spacer group may include a first spacer P1, a second spacer P2 and a third spacer P3.

[0126] The structure of the optical element group of this embodiment is the same as that of the optical element group of Embodiment 4, that is, the basic parameter table of the visual system of this embodiment is the same as Table 3, and the aspheric coefficient table is the same as Table 4. The difference between this embodiment and Embodiment 4 is that the structural dimensions of at least some components in the lens barrel and the spacer group are different.

[0127] Fig.9A The axial chromatic aberration curve of the visual system of Example 4, 5 or 6 is shown, which indicates the deviation of the focal point of light of different wavelengths after passing through the visual system. Fig. 9B The astigmatism curve of the visual system of Example 4, 5 or 6 is shown, which represents the meridional image plane curvature and sagittal image plane curvature corresponding to different field angles. Fig. 9C The distortion curves of the visual systems of Embodiments 4, 5 or 6 are shown, which represent the distortion magnitude values ​​corresponding to different field angles. 9A to 9C It can be seen that the visual system provided in Example 4, 5 or 6 can achieve good imaging quality.

[0128] Example 7

[0129] The following reference Fig.10 Describe the visual system according to Example 7 of the present application.

[0130] like Fig.10 As shown, the visual system may include a lens barrel and an optical element group and a spacer group placed in the lens barrel.

[0131] The optical element group may include a first element group, a second element group, a third element group and a fourth element group arranged in sequence from the first side to the second side along the optical axis. The first element group may include a reflective polarizing element RP, a quarter wave plate QWP and a first lens E1. The second element group may include a second lens E2. The third element group may include a third lens E3. The fourth element group may include a fourth lens E4. A stop STO (not shown) may also be provided between the first side and the first lens E1. A partial reflection layer BS (not shown) may also be provided on the second side of the fourth lens E4. The spacer group may include a first spacer P1, a second spacer P2 and a third spacer P3. The first side of each element (the first lens E1, the second lens E2, the third lens E3, the fourth lens E4) is referred to as a side near the human eye, and the second side is referred to as a side near the screen.

[0132] The first lens E1 has negative focal power, and its side S1 near the human eye is convex, and its side S2 near the screen is concave. The second lens E2 has positive focal power, and its side S3 near the human eye is convex, and its side S4 near the screen is convex. The third lens E3 has positive focal power, and its side S5 near the human eye is concave, and its side S6 near the screen is convex. The fourth lens E4 has positive focal power, and its side S7 near the human eye is concave, and its side S8 near the screen is convex. The quarter-wave plate QWP is attached to the side S1 near the human eye of the first lens E1. The reflective polarizing element RP is attached to the side surface of the quarter-wave plate QWP away from the first lens E1. The partial reflection layer BS is attached to the side S8 near the screen of the fourth lens E4.

[0133] In this example, an image surface IMG may be provided on the second side of the visual system, and the image surface IMG may be provided with a display screen, for example. After the image light from the image surface IMG passes through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter wave plate QWP in sequence and reaches the reflective polarizing element RP, a first reflection occurs at the reflective polarizing element RP. After the light reflected for the first time passes through the quarter wave plate QWP, the first lens E1, the second lens E2, the third lens E3, the fourth lens E4 and reaches the partial reflection layer BS located on the near-screen side S8 of the fourth lens E4, a second reflection occurs at the partial reflection layer BS. The light reflected for the second time passes through the fourth lens E4, 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 STO in sequence and is finally projected into the eyes of the user. For example, the light of the visual system after two reflections is finally projected into the eyes of the user.

[0134] Table 5 shows the basic parameters of the visual system of Example 7, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm). The image light from the image surface IMG passes through the components in the order of sequence number 27 to sequence number 1 and is finally projected into the human eye.

[0135]

[0136]

[0137] Table 5

[0138] In this embodiment, the side surfaces near the human eye and the side surfaces near the screen of the first lens E1 to the fourth lens E4 are all aspherical surfaces. Table 6 shows the high-order coefficients A4, A6, A8, A10, A12 and A14 of the aspherical surfaces S1-S8 that can be used in Embodiment 7.

[0139] Face number A4 A6 A8 A10 A12 S14 S1 -7.1107E-07 -4.2208E-10 3.8974E-13 3.1985E-15 5.3051E-18 -3.7477E-21 S2 -1.7576E-06 1.1155E-08 5.8581E-12 1.6095E-14 0.0000E+00 0.0000E+00 S3 -6.8915E-06 -1.4179E-09 -8.3455E-12 0.0000E+00 0.0000E+00 0.0000E+00 S4 -1.7975E-06 -3.2839E-09 -8.2407E-12 3.2358E-14 0.0000E+00 0.0000E+00 S5 2.7638E-09 1.7342E-10 2.5928E-14 -1.3534E-15 -1.0255E-17 0.0000E+00 S6 1.0474E-08 -2.0065E-10 -2.1802E-13 1.8373E-16 4.0935E-18 0.0000E+00 S7 -1.3542E-06 2.6511E-09 -2.2902E-13 0.0000E+00 0.0000E+00 0.0000E+00 S8 1.0141E-07 -2.5262E-10 -2.3053E-12 -8.9827E-15 0.0000E+00 0.0000E+00

[0140] Table 6

[0141] Example 8

[0142] The following reference Fig.11 Describe the visual system according to Example 8 of the present application.

[0143] like Fig.11 As shown, the visual system may include a lens barrel and an optical element group and a spacer group placed in the lens barrel. The optical element group may include a first element group, a second element group, a third element group and a fourth element group arranged in sequence from the first side to the second side along the optical axis. The first element group may include a reflective polarizing element RP, a quarter wave plate QWP and a first lens E1. The second element group may include a second lens E2. The third element group may include a third lens E3. The fourth element group may include a fourth lens E4. A stop STO (not shown) may also be provided between the first side and the first lens E1. The second side of the fourth lens E4 may also be provided with a partial reflection layer BS (not shown). The spacer group may include a first spacer P1, a second spacer P2 and a third spacer P3.

[0144] The structure of the optical element group of this embodiment is the same as that of the optical element group of Embodiment 7, that is, the basic parameter table of the visual system of this embodiment is the same as Table 5, and the aspheric coefficient table is the same as Table 6. The difference between this embodiment and Embodiment 7 is that the structural dimensions of at least some components in the lens barrel and the spacer group are different.

[0145] Example 9

[0146] The following reference Fig.12 Describe the visual system according to Example 9 of the present application.

[0147] like Fig.12 As shown, the visual system may include a lens barrel and an optical element group and a spacer group placed in the lens barrel. The optical element group may include a first element group, a second element group, a third element group and a fourth element group arranged in sequence from the first side to the second side along the optical axis. The first element group may include a reflective polarizing element RP, a quarter wave plate QWP and a first lens E1. The second element group may include a second lens E2. The third element group may include a third lens E3. The fourth element group may include a fourth lens E4. A stop STO (not shown) may also be provided between the first side and the first lens E1. The second side of the fourth lens E4 may also be provided with a partial reflection layer BS (not shown). The spacer group may include a first spacer P1, a second spacer P2 and a third spacer P3.

[0148] The structure of the optical element group of this embodiment is the same as that of the optical element group of Embodiment 7, that is, the basic parameter table of the visual system of this embodiment is the same as Table 5, and the aspheric coefficient table is the same as Table 6. The difference between this embodiment and Embodiment 7 is that the structural dimensions of at least some components in the lens barrel and the spacer group are different.

[0149] Fig.13A The axial chromatic aberration curve of the visual system of Example 7, 8 or 9 is shown, which indicates the deviation of the focal point of light of different wavelengths after passing through the visual system. Fig. 13B The astigmatism curve of the visual system of Example 7, 8 or 9 is shown, which represents the meridional image plane curvature and sagittal image plane curvature corresponding to different field angles. Fig. 13C The distortion curves of the visual systems of Embodiments 7, 8 or 9 are shown, which represent the distortion magnitude values ​​corresponding to different field angles. FIG. 13A to FIG. 13C It can be seen that the visual system provided in Example 7, 8 or 9 can achieve good imaging quality.

[0150] Table 7 shows the values ​​of parameters such as f, Fno, FG1, FG2, FG3, FG4, TD, etc. in each embodiment of Examples 1 to 9. Among them, the units of f, FG1, FG2, FG3, FG4, TD in Table 7 are all millimeters (mm).

[0151] Parameters / Examples 1, 2 and 3 4, 5 and 6 7, 8 and 9 f 15.9385 15.8832 15.7304 Fno 3.7369 3.5047 3.9329 FG1 -628.5496 -302.8558 -399.5329 FG2 146.8356 123.7133 90.3003 FG3 infinity infinity 497.4454 FG4 88.8213 91.1180 149.3686 TD 11.4393 11.7253 11.8490

[0152] Table 7

[0153] Table 8 gives the values ​​of parameters such as d1m, D1m, d2s, d2m, D2m, d3s, D3m, d0s, d0m, EP01, CP1, EP12, CP2, EP23, CP3 and L in each embodiment 1-9. The above parameters can be calculated according to Figure 1The parameters listed in Table 8 are measured using the marking method shown in the figure, and the units of the parameters listed in Table 8 are all millimeters (mm).

[0154]

[0155]

[0156] Table 8

[0157] In summary, Table 9 shows the values ​​of the conditional expressions of each of Examples 1 to 9.

[0158] Conditional / Example 1 2 3 4 5 6 7 8 9 FG1 / f -39.44 -39.44 -39.44 -19.07 -19.07 -19.07 -25.40 -25.40 -25.40 CT1 / (CP1+T12) 3.76 3.76 3.76 3.68 3.68 3.68 1.82 1.82 1.82 R3 / R4 -0.36 -0.36 -0.36 -0.21 -0.21 -0.21 -0.03 -0.03 -0.03 R3×N2 / D1m 4.81 4.81 4.87 3.73 3.73 3.75 2.40 2.40 2.41 f / (L-TD) -24.32 -20.56 -24.32 -16.87 -16.87 -12.80 -8.17 -6.91 -6.48 d0s / d0m 0.88 0.88 0.89 0.96 0.96 0.95 0.90 0.89 0.89 EP01 / (CTR+CTQ+CT1) 1.70 1.70 1.70 2.87 2.87 2.87 3.01 2.76 2.65 FG2 / d2s×N2 5.81 5.87 5.92 5.23 5.14 5.15 3.70 3.74 3.71 (d0m-DT42) / (d0s-DT11) 1.28 1.27 1.25 1.09 1.09 1.10 1.11 1.14 1.14 CT2 / (EP12+CP2) 1.35 1.35 1.35 1.56 1.56 1.56 1.77 1.77 1.31 (D2m-d2m) / (D1m-d1m) 0.62 0.65 0.62 0.83 0.66 0.67 0.69 0.88 0.80 EP23 / CT3 / / / 1.00 1.00 1.00 0.67 0.67 2.67 CP3 / T34 / / / 0.08 0.08 0.08 1.65 1.65 1.65 CT4 / (D3m-d3s) / / / 1.15 1.30 1.51 1.86 1.86 2.10

[0159] Table 9

[0160] The present application also provides an optical device, which may be an independent projection device such as a projector, or a projection module integrated in a mobile electronic device such as a virtual reality device. The optical device is equipped with the visual system described above.

[0161] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the utility model involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present application (but not limited to) by each other.

Claims

1. A visual system, characterized in that: Comprising: An optical element group, including a first element group with negative optical power, a second element group with positive optical power, a third element group, and a fourth element group with positive optical power, which are arranged in sequence from the first side to the second side along the optical axis; the first element group includes a reflective polarizing element, a quarter-wave plate, and a first lens; the second element group includes a second lens; the third element group includes a third lens; the fourth element group includes a fourth lens; A spacer group, including a first spacer, which is placed on the second side surface of the first lens and is in contact with the second side surface of the first lens; And A lens barrel, in which the optical element group and the spacer group are placed; Wherein, the effective focal length FG1 of the first element group and the total effective focal length f of the visual system satisfy: -41 < FG1 / f < -18; The central thickness CT1 of the first lens on the optical axis, the interval distance T12 between the first lens and the second lens on the optical axis, and the maximum thickness CP1 of the first spacer satisfy: 1.5 < CT1 / (CP1 + T12) < 4.

5.

2. The visual system according to claim 1, characterized in that: The curvature radius R3 of the first side surface of the second lens and the curvature radius R4 of the second side surface of the second lens satisfy: -0.5 < R3 / R4 < 0; and the curvature radius R3 of the first side surface of the second lens, the refractive index N2 of the second lens, and the outer diameter D1m of the second side surface of the first spacer satisfy: 1.8 < R3×N2 / D1m < 5.

3.

3. The visual system according to claim 1, characterized in that: The total effective focal length f of the visual system, the axial distance TD from the first side surface of the first lens to the second side surface of the fourth lens, and the maximum length L of the lens barrel along the direction of the optical axis satisfy: -26 < f / (L - TD) < -5.

4. The visual system according to claim 1, characterized in that: 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: 0.5 < d0s / d0m < 1.

5. The visual system according to claim 1, characterized in that: The interval distance EP01 between the first side end surface of the lens barrel and the first side surface of the first spacer along 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 central thickness CT1 of the first lens on the optical axis satisfy: 1 < EP01 / (CTR + CTQ + CT1) < 3.

5.

6. The visual system according to claim 1, characterized in that: The inner diameter d0s of the first side end surface of the lens barrel, the inner diameter d0m of the second side end surface of the lens barrel, the effective full aperture DT11 of the first side surface of the first lens, and the effective full aperture DT42 of the second side surface of the fourth lens satisfy: 0.5 < (d0m - DT42) / (d0s - DT11) < 1.

5.

7. The visual system according to any one of claims 1 to 6, characterized in that: The spacer group further includes a second spacer, which is placed on the second side surface of the second lens and is in contact with the second side surface of the second lens; Wherein, the effective focal length FG2 of the second lens group, the refractive index N2 of the second lens, and the inner diameter d2s of the first side surface of the second spacer satisfy: 3 < FG2 / d2s×N2 < 6.

8. The visual system according to any one of claims 1 to 6, characterized in that: The spacer group further includes a second spacer, which is disposed on the second side surface of the second lens and in contact with the second side surface of the second lens; Wherein, the central thickness CT2 of the second lens on the optical axis, the spacing distance EP12 along the optical axis between the second side surface of the first spacer and the first side surface of the second spacer, and the maximum thickness CP2 of the second spacer satisfy: 1 < CT2 / (EP12 + CP2) < 2.

9. The visual system according to any one of claims 1 to 6, characterized in that: The spacer group further includes a second spacer, which is disposed on the second side surface of the second lens and in contact with the second side surface of the second lens; Wherein, the inner diameter d1m of the second side surface of the first spacer, the outer diameter D1m of the second side surface of the first spacer, the inner diameter d2m of the second side surface of the second spacer, and the outer diameter D2m of the second side surface of the second spacer satisfy: 0 < (D2m - d2m) / (D1m - d1m) < 1.

10. The visual system according to any one of claims 1 to 6, characterized in that: The spacer group further includes a second spacer and a third spacer. The second spacer is disposed on the second side surface of the second lens and in contact with the second side surface of the second lens. The third spacer is disposed on the second side surface of the third lens and in contact with the second side surface of the third lens; Wherein, the central thickness CT3 of the third lens on the optical axis and the spacing distance EP23 along the optical axis between the second side surface of the second spacer and the first side surface of the third spacer satisfy: 0 < EP23 / CT3 < 3; and the maximum thickness CP3 of the third spacer and the spacing distance T34 between the third lens and the fourth lens on the optical axis satisfy: 0 < CP3 / T34 < 2.

11. The visual system according to any one of claims 1 to 6, characterized in that: The spacer group further includes a third spacer, which is disposed on the second side surface of the third lens and in contact with the second side surface of the third lens; Wherein, the central thickness CT4 of the fourth lens on the optical axis, the inner diameter d3s of the first side surface of the third spacer, and the outer diameter D3m of the second side surface of the third spacer satisfy: 1 < CT4 / (D3m - d3s) < 2.

5.

12. The visual system according to any one of claims 1 to 6, characterized in that: The Abbe number of any one of the first lens to the fourth lens is less than 25.

13. The visual system according to any one of claims 1 to 6, characterized in that: The quarter-wave plate is disposed on the first side surface of the first lens, and the reflective polarizing element is disposed on the first side surface of the quarter-wave plate.

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