Visual system

Abstract

The utility model discloses a visual system which 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 lens with positive focal power, a reflective polarization element, a first quarter-wave plate, a second lens with positive focal power, a third lens with negative focal power, a partial reflection element and a second quarter-wave plate which are sequentially arranged from the first side to the second side along the optical axis; a polarizer and a fourth lens having positive focal power; the spacer group includes a first spacer in contact with the second side surface of the first lens, and a second spacer in contact with the second side surface of the second lens; wherein a distance EP12 between the first spacer and the second spacer along the optical axis and an on-axis distance T12 from the second side surface of the first lens to the first side surface of the second lens satisfy: 1.3 lt; eP12 / T12lt; 3.8); the distance EP01 between the first side end face of the lens barrel and the first spacer along the optical axis, the maximum thickness CP1 of the first spacer and the center thickness CT1 of the first lens on the optical axis satisfy 1.3 lt; (EP01 + CP1) / CT1lt; and 1.75.

Description

Technical Field

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

[0002] With the introduction of the concept of the metaverse, virtual reality and augmented reality technologies for human-computer interaction have ushered in a second opportunity for development. As an important entrance to human-computer interaction, the visual system plays a key role in it. The visual system is 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 of the visual system itself, and it reserves space for the overall design of virtual reality equipment or augmented reality equipment, and has become the mainstream trend of research and development.

[0003] The catadioptric optical system can shorten the length of the visual system by bending the optical path, thereby moving the center of gravity of the virtual reality device or augmented reality device backward and improving the user experience. However, the existing catadioptric optical system usually uses two lenses, which will cause the picture of the catadioptric optical system to be blurred and the image quality to be poor. Utility Model Content

[0004] One aspect of the present application provides a visual system that includes a lens barrel and an optical element group and a spacer group placed in the lens barrel. The optical element group includes a first lens with positive focal power, a reflective polarizing element, a first quarter-wave plate, a second lens with positive focal power, a third lens with negative focal power, a partial reflection element, a second quarter-wave plate, a polarizer, and a fourth lens with positive focal power, which are arranged in sequence from the first side to the second side along the optical axis. The spacer group includes a first spacer and a second spacer, the first spacer is placed on the second side of the first lens and contacts the second side of the first lens, and the second spacer is placed on the second side of the second lens and contacts the second side of the second lens. Wherein, the distance EP12 between the first spacer and the second spacer along the optical axis and the on-axis distance T12 from the second side of the first lens to the first side of the second lens satisfy: 1.3 <EP12 / T12<3.8;镜筒的第一侧端面和第一间隔件沿光轴的距离EP01、第一间隔件的最大厚度CP1与第一透镜在光轴上的中心厚度CT1满足:1.3<(EP01+CP1) / CT1<1.75。

[0005] According to an exemplary embodiment of the present application, the effective focal length f1 of the first lens and the outer diameter D1s of the first side surface of the first spacer satisfy: 1.2 <f1 / D1s<1.7。

[0006] According to an exemplary embodiment of the present application, the combined focal length fz1 of the reflective polarizing element, the first quarter-wave plate, and the second lens, the inner diameter d1m of the second side surface of the first spacer, and the outer diameter D1m of the second side surface of the first spacer satisfy: 1.6 < fz1 / (d1m + D1m) < 2.6.

[0007] According to an exemplary embodiment of the present application, the radius of curvature R2 of the second side surface of the first lens and the inner diameter d1s of the first side surface of the first spacer satisfy: 2.15 < R2 / d1s < 3.4.

[0008] According to an exemplary embodiment of the present application, the central thickness CTR of the reflective polarizing element on the optical axis, the central thickness CTQ1 of the first quarter-wave plate on the optical axis, the central thickness CT2 of the second lens on the optical axis, and the inner diameter d2s of the first side surface of the second spacer satisfy: 4.1 < d2s / (CTR + CTQ1 + CT2) < 7.2.

[0009] According to an exemplary embodiment of the present application, the inner diameter d0m of the second side end surface of the lens barrel, the outer diameter D0m of the second side end surface of the lens barrel, and the length L of the lens barrel in the direction of the optical axis satisfy: 0.3 < (D0m - d0m) / L < 0.75.

[0010] According to an exemplary embodiment of the present application, the outer diameter D0s of the first side end surface of the lens barrel and the entrance pupil diameter EPD of the visual system satisfy: 1.7 ≤ D0s / EPD < 1.95.

[0011] According to an exemplary embodiment of the present application, the outer diameter D2s of the first side surface of the second spacer, the outer diameter D2m of the second side surface of the second spacer, and the total effective focal length f of the visual system satisfy: 1.35 < (D2s + D2m) / f < 1.75.

[0012] 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 on-axis distance TD from the first side surface of the first lens to the second side surface of the fourth lens satisfy: 1.4 < d0s / TD < 1.7.

[0013] According to an exemplary embodiment of the present application, the length L of the lens barrel in the direction of the optical axis and the radius of curvature R1 of the first side surface of the first lens satisfy: 1.4 < L / R1 < 1.6.

[0014] According to an exemplary embodiment of the present application, the spacer group further includes a third spacer, which is placed on the second side surface of the third lens and in contact with the second side surface of the third lens. Among them, the distance EP23 between the second spacer and the third spacer along the optical axis, the maximum thickness CP2 of the second spacer, and the central thickness CT3 of the third lens on the optical axis satisfy: 1.65 < (CP2 + EP23) / CT3 < 2.1.

[0015] According to an exemplary embodiment of the present application, the spacer group further includes a third spacer, which is placed on the second side surface of the third lens and in contact with the second side surface of the third lens. Among them, the effective focal length f3 of the third lens, the inner diameter d3s of the first side surface of the third spacer, and the outer diameter D3s of the first side surface of the third spacer satisfy: -2.6 ≤ f3 / (d3s + D3s) < -1.7.

[0016] According to an exemplary embodiment of the present application, the spacer group further includes a third spacer, which is placed on the second side surface of the third lens and in contact with the second side surface of the third lens. Among them, the inner diameter d2m of the second side surface of the second spacer and the inner diameter d3m of the second side surface of the third spacer satisfy: 1.5 < d2m / d3m < 1.85.

[0017] According to an exemplary embodiment of the present application, the spacer group further includes a third spacer, which is placed on the second side surface of the third lens and in contact with the second side surface of the third lens. Among them, the outer diameter D3m of the second side surface of the third spacer, the Abbe number V3 of the third lens, and the refractive index N3 of the third lens satisfy: 1.5 mm < D3m / (V3 / N3) < 1.9 mm.

[0018] According to an exemplary embodiment of the present application, the spacer group further includes a third spacer, which is placed on the second side surface of the third lens and in contact with the second side surface of the third lens. The maximum thickness CP3 of the third spacer, the central thickness CTQ2 of the second quarter-wave plate on the optical axis, and the central thickness CTL of the polarizer on the optical axis satisfy: 0.15 < CP3 / (CTQ2 + CTL) < 0.6.

[0019] The visual system provided by this application uses four lenses. By controlling the relationship between the distance of the first spacer and the second spacer along the optical axis and the on-axis distance from the second side of the first lens to the first side of the second lens, as well as the relationship between the distance of the first side end face of the lens barrel and the first spacer along the optical axis, and the relationship between the maximum thickness of the first spacer and the central thickness of the first lens on the optical axis, the shapes of the first lens and the second lens can be constrained. While ensuring the optical performance of the visual system, the processability of the first lens and the second lens can be improved; at the same time, the length of the lens barrel along the direction of the optical axis can also be limited, which is beneficial to the miniaturization of the visual system, and ensures an appropriate on-axis distance from the first side of the first lens to the first side end face of the lens barrel, avoiding problems such as the first lens being easily scratched due to the outward protrusion of the first lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Other features, objects, and advantages of this application will become more apparent by reading the detailed description of the non-limiting embodiments with reference to the following drawings. Among them:

[0021] Figure 1 FIG. shows a schematic diagram of parameter labeling of the visual system according to this application;

[0022] Figure 2 FIG. shows a schematic structural diagram of the visual system according to Embodiment 1 of this application;

[0023] Figure 3 FIG. shows a schematic structural diagram of the visual system according to Embodiment 2 of this application;

[0024] Figure 4 FIG. shows a schematic structural diagram of the visual system according to Embodiment 3 of this application;

[0025] Figure 5A , Figure 5B , Figure 5C , Figure 5D respectively show the axial chromatic aberration curve, astigmatism curve, distortion curve, and modulation transfer function (MTF) curve of the visual system according to Embodiment 1, 2, or 3 of this application;

[0026] Figure 6 FIG. shows a schematic structural diagram of the visual system according to Embodiment 4 of this application;

[0027] Figure 7 FIG. shows a schematic structural diagram of the visual system according to Embodiment 5 of this application;

[0028] Figure 8 FIG. shows a schematic structural diagram of the visual system according to Embodiment 6 of this application;

[0029] Figure 9A , Figure 9B , Figure 9C , Figure 9D respectively show the axial chromatic aberration curve, astigmatism curve, distortion curve, and modulation transfer function curve of the visual system according to Embodiment 4, 5, or 6 of the present application;

[0030] Figure 10 shows a schematic structural diagram of the visual system according to Embodiment 7 of the present application;

[0031] Figure 11 shows a schematic structural diagram of the visual system according to Embodiment 8 of the present application;

[0032] Figure 12 shows a schematic structural diagram of the visual system according to Embodiment 9 of the present application; and

[0033] Figure 13A , Figure 13B , Figure 13C , Figure 13D respectively show the axial chromatic aberration curve, astigmatism curve, distortion curve, and modulation transfer function curve of the visual system according to Embodiment 7, 8, or 9 of the present application. Detailed Embodiments

[0034] To better understand the present application, more detailed descriptions of various aspects of the present application will be made 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 reference numerals refer to the same elements.

[0035] It should be noted that in this specification, the expressions such as first, second, and third are only used to distinguish one feature from another feature and do not represent any limitation on the feature. Therefore, without departing from the teachings of the present application, the first lens discussed below may also be referred to as the second lens or the third lens.

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

[0037] In this text, 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 (such as the side close to the human eye) is called the first side surface of the lens, and the surface of each lens closest to the second side (such as the side close to the display screen) is called the second side surface of the lens.

[0038] It should also be understood that the terms "comprise", "comprising", "have", "including" and / or "containing", when used in this specification, denote the presence of the stated features, elements and / or components, but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when describing the embodiments of the present application, the use of "may" means "one or more embodiments of the present application". And the term "exemplary" is intended to refer to an example or illustration.

[0039] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms (such as those defined in a common dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0040] It should be noted that, without conflict, the embodiments and features in the embodiments of the present application may be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0041] The features, principles and other aspects of the present application will be described in detail below.

[0042] Referring to Figures 2 to 4 、 Figures 6 to 8 and Figures 10 to 12 , a first aspect of the present application provides a visual system that may include an optical element group, and the optical element group may include a first lens, a reflective polarizing element, a first quarter-wave plate, a second lens, a third lens, a partially reflective element, a second quarter-wave plate, a polarizer and a fourth lens arranged in sequence along the optical axis from the first side to the second side.

[0043] In an exemplary embodiment, the first lens may have a positive optical power. The second lens may have a positive optical power. The third lens may have a negative optical power. The fourth lens may have a positive optical power. Reasonably configuring the optical powers of the respective lenses is beneficial to improving the imaging quality of the visual system.

[0044] In an exemplary embodiment, the first side surface of the first lens may be convex, and the second side surface may be concave.

[0045] In an exemplary embodiment, the first side surface of the second lens may be planar, and the second side surface may be convex.

[0046] In an exemplary embodiment, the first side surface of the third lens may be concave, and the second side surface may be convex.

[0047] In an exemplary embodiment, the first side surface of the fourth lens may be planar, and the second side surface may be convex.

[0048] In an exemplary embodiment, the first quarter-wave plate may be disposed on the first side surface of the second lens and at least partially adhered to the first side surface of the second lens. The first quarter-wave plate is used to change the polarization state of light. For example, it can convert circularly polarized light into linearly polarized light, or convert linearly polarized light into circularly polarized light. The circularly polarized light may include right-handed circularly polarized light or left-handed circularly polarized light. The linearly polarized light may include S linearly polarized light or P linearly polarized light.

[0049] In an exemplary embodiment, the reflective polarizing element may be disposed on the first side surface of the first quarter-wave plate and at least partially adhered to the first side surface of the first quarter-wave plate. The reflective polarizing element is used to reflect linearly polarized light in a predetermined direction and transmit linearly polarized light orthogonal to the predetermined direction. For example, the reflective polarizing element can reflect S linearly polarized light and transmit P linearly polarized light, or the reflective polarizing element can reflect P linearly polarized light and transmit S linearly polarized light.

[0050] In an exemplary embodiment, the partial reflection element may be disposed on the second side surface of the third lens and at least partially adhered to the second side surface of the third lens. The partial reflection element has a semi-transmissive and semi-reflective effect on light. By disposing the partial reflection element on the second side surface of the third lens and combining it with the reflective polarizing element and the first quarter-wave plate, the light can be refracted and reflected multiple times, effectively reducing the body length of the visual system.

[0051] In an exemplary embodiment, the polarizer may be disposed on the first side surface of the fourth lens and at least partially adhered to the first side surface of the fourth lens. The second quarter-wave plate may be disposed on the first side surface of the polarizer and at least partially adhered to the first side surface of the polarizer.

[0052] In an exemplary embodiment, the visual system may further include a diaphragm, which may be disposed on the first side of the first lens. As an example, the diaphragm may be, for example, the pupil of the user. The image light from the second side passes through the fourth lens, the polarizer, the second quarter-wave plate, the partial reflection element, the third lens, the second lens, the first quarter-wave plate, the reflective polarizing element, the first lens, etc., and is finally projected onto the user's eye on the first side after multiple refractions and reflections.

[0053] In an exemplary embodiment, the first side may be the side of the human eye, and the second side may be the side of the display screen. Accordingly, the first side surfaces of the respective elements (the first lens, the reflective polarizing element, the first quarter-wave plate, the second lens, the third lens, the second quarter-wave plate, the polarizer, the fourth lens) may be referred to as the side surfaces near the human eye, and the second side surfaces may be referred to as the side surfaces near the screen.

[0054] In an exemplary embodiment, an image plane may be provided on the second side of the visual system. A display screen may be provided on the image plane. The image light from the display screen may sequentially pass through the fourth lens, the polarizer, the second quarter-wave plate, the third lens, the second lens, the first quarter-wave plate, reach the reflective polarizing element, and then be reflected at the reflective polarizing element to form the first reflected image light. The first reflected image light passes through the first quarter-wave plate, the second lens, the third lens and reaches the partial reflection element on the second side surface of the third lens, and then is reflected at the partial reflection element to form the second reflected image light. The second reflected image light sequentially passes through the third lens, the second lens, the first quarter-wave plate, the reflective polarizing element, the first lens and is finally projected onto the user's eye. The visual system provided in the present application folds the required optical path in a manner of combining light reflection and refraction without affecting the projection quality, effectively shortening the body length of the visual system.

[0055] 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. Reasonable use of the spacers can effectively avoid the risk of stray light, reduce the interference to the image quality, and thus improve the imaging quality of the visual system.

[0056] In an exemplary embodiment, the visual system may further include a lens barrel. The optical element group and the spacer group may be disposed inside the lens barrel. The lens barrel may include a first side end face, a second side end face, an outer ring face, and an inner ring face. Among them, the end face of the lens barrel closest to the first side is the first side end face of the lens barrel, and the end face of the lens barrel closest to the second side is the second side end face of the lens barrel; in the direction perpendicular to the optical axis, the surface of the lens barrel farthest from the optical axis is the outer ring face, and the surface of the lens barrel closest to the optical axis is the inner ring face.

[0057] In an exemplary embodiment, the spacer group may include a first spacer and a second spacer. The first spacer may be disposed on the second side surface of the first lens and at least partially in contact with the second side surface of the first lens. The second spacer may be disposed on the second side surface of the second lens and at least partially in contact with the second side surface of the second lens. The distance EP12 between the first spacer and the second spacer along the optical axis and the axial distance T12 from the second side surface of the first lens to the first side surface of the second lens may satisfy: 1.3 < EP12 / T12 < 3.8; the distance EP01 between the first side end surface of the lens barrel and the first spacer along the optical axis, the maximum thickness CP1 of the first spacer, and the central thickness CT1 of the first lens on the optical axis may satisfy: 1.3 < (EP01 + CP1) / CT1 < 1.75. By controlling the above conditional expressions, the shapes of the first lens and the second lens can be constrained. While ensuring the optical performance of the visual system, the processability of the first lens and the second lens can be improved; at the same time, the length of the lens barrel in the direction along the optical axis can also be restricted, which is beneficial to the miniaturization of the visual system and ensures an appropriate axial distance from the first side surface of the first lens to the first side end surface of the lens barrel, avoiding problems such as the first lens being easily scratched due to the outward protrusion of the first lens.

[0058] In an exemplary embodiment, the spacer group may include a first spacer. The first spacer may be disposed on the second side surface of the first lens and at least partially in contact with the second side surface of the first lens. The effective focal length f1 of the first lens and the outer diameter D1s of the first side surface of the first spacer may satisfy: 1.2 < f1 / D1s < 1.7. Reasonably configuring the ratio of the effective focal length of the first lens to the outer diameter of the first side surface of the first spacer can enable the first lens to have an appropriate converging ability for light, adjust the focusing position of the light, and constrain the overall shape of the first lens, improving the processability of the first lens; at the same time, the outer diameter of the first side surface of the first spacer can also be restricted to meet the assembly requirements at the module end.

[0059] In an exemplary embodiment, the spacer group may include a first spacer, and the first spacer may be disposed on the second side surface of the first lens and at least partially in contact with the second side surface of the first lens. The combined focal length fz1 of the reflective polarizing element, the first quarter-wave plate, and the second lens, the inner diameter d1m of the second side surface of the first spacer, and the outer diameter D1m of the second side surface of the first spacer may satisfy: 1.6 < fz1 / (d1m + D1m) < 2.6. Reasonably configuring the ratio of the combined focal length of the reflective polarizing element, the first quarter-wave plate, and the second lens to the sum of the inner and outer diameters of the second side surface of the first spacer is beneficial to restricting the light transmittance of the visual system and ensuring that the field of view angle of the visual system is within an appropriate range; at the same time, the buffering characteristics of the first spacer material can be utilized to avoid direct contact between the reflective polarizing element and the first lens, reduce the assembly stress, improve the assembly yield of the visual system, and improve the drop reliability of the visual system.

[0060] In an exemplary embodiment, the spacer group may include a first spacer, and the first spacer may be disposed on the second side surface of the first lens and at least partially in contact with the second side surface of the first lens. The radius of curvature R2 of the second side surface of the first lens and the inner diameter d1s of the first side surface of the first spacer may satisfy: 2.15 < R2 / d1s < 3.4. Reasonably configuring the ratio of the radius of curvature of the second side surface of the first lens to the inner diameter of the first side surface of the first spacer can restrict the shape of the second side surface of the first lens, ensure that the first lens has sufficient converging ability for light, and avoid the problem of poor overall imaging quality of the visual system caused by too large a curvature of the second side surface of the first lens; at the same time, it can also make the inner diameter of the first side surface of the first spacer appropriate, ensure that the first spacer effectively blocks excess light, reduce the stray light risk of the visual system, and improve the imaging quality of the visual system.

[0061] In an exemplary embodiment, the spacer group may include a second spacer, and the second spacer may be disposed on the second side surface of the second lens and at least partially in contact with the second side surface of the second lens. The central thickness CTR of the reflective polarizing element on the optical axis, the central thickness CTQ1 of the first quarter-wave plate on the optical axis, the central thickness CT2 of the second lens on the optical axis, and the inner diameter d2s of the first side surface of the second spacer may satisfy: 4.1 < d2s / (CTR + CTQ1 + CT2) < 7.2. By controlling the above conditional expression, the body length of the visual system can be restricted, the compact design of the visual system can be achieved, the volume and weight of the device including the visual system can be reduced, and the wearing convenience of the device including the visual system can be improved; at the same time, it can also make the inner diameter of the first side surface of the second spacer within a reasonable range, ensure that the second spacer and the second lens have sufficient bearing width, and avoid the generation of stray light due to the direct incidence of light on the inner diameter surface of the second spacer caused by too small an inner diameter of the first side surface of the second spacer, and improve the imaging quality of the visual system.

[0062] In an exemplary embodiment, the inner diameter d0m of the second side end face of the lens barrel, the outer diameter D0m of the second side end face of the lens barrel, and the length L of the lens barrel in the direction of the optical axis may satisfy: 0.3 < (D0m - d0m) / L < 0.75. By reasonably configuring the ratio of the difference between the outer and inner diameters of the second side end face of the lens barrel to the length of the lens barrel in the direction of the optical axis, it is possible to ensure that the second side end face of the lens barrel has sufficient bearing width during the assembly process, improve the assembly stability of the visual system, and ensure that the second side end face of the lens barrel has an appropriate inner diameter without affecting the assembly stability of the visual system, thereby avoiding the generation of sharp corner stray light on the second side end face of the lens barrel; at the same time, it is also possible to limit the length of the lens barrel in the direction of the optical axis, constrain the overall shape of the lens barrel, and achieve miniaturization of the visual system.

[0063] In an exemplary embodiment, the outer diameter D0s of the first side end face of the lens barrel and the entrance pupil diameter EPD of the visual system may satisfy: 1.7 ≤ D0s / EPD < 1.95. By reasonably configuring the ratio of the outer diameter of the first side end face of the lens barrel to the entrance pupil diameter of the visual system, it is possible to ensure sufficient light input for the effective light beam of the visual system, constrain the maximum outer diameter of the visual system, and achieve miniaturization of the visual system; at the same time, it is also possible to limit the entrance pupil diameter of the visual system within an appropriate range to meet the ergonomic design and improve the immersive experience of the visual system and the device including the visual system.

[0064] In an exemplary embodiment, the spacer group may include a second spacer, and the second spacer may be placed on the second side face of the second lens and at least partially in contact with the second side face of the second lens. The outer diameter D2s of the first side face of the second spacer, the outer diameter D2m of the second side face of the second spacer, and the total effective focal length f of the visual system may satisfy: 1.35 < (D2s + D2m) / f < 1.75. By reasonably configuring the ratio of the sum of the outer diameters of the first side face and the second side face of the second spacer to the total effective focal length of the visual system, it is possible to keep the aberration of the visual system at an appropriate level, which is beneficial to the imaging of the visual system; at the same time, it is also beneficial to constrain the outer diameters of the second lens and the third lens, thereby improving the processability of the second lens and the third lens.

[0065] In an exemplary embodiment, the inner diameter d0s of the first side end face of the lens barrel and the on-axis distance TD from the first side face of the first lens to the second side face of the fourth lens may satisfy: 1.4 < d0s / TD < 1.7. Reasonably configuring the ratio of the inner diameter of the first side end face of the lens barrel to the on-axis distance from the first side face of the first lens to the second side face of the fourth lens is beneficial to improving the clarity and accuracy of imaging of the visual system, providing higher-quality image output, reducing the fluctuations and instabilities of the visual system, ensuring the long-term stable operation of the visual system; at the same time, it can also control the overall size of the visual system to meet the requirements of the module end, and achieve miniaturization of the visual system while ensuring the optical performance of the visual system.

[0066] In an exemplary embodiment, the length L of the lens barrel in the direction of the optical axis and the curvature radius R1 of the first side face of the first lens may satisfy: 1.4 < L / R1 < 1.6. Reasonably configuring the ratio of the length of the lens barrel in the direction of the optical axis to the curvature radius of the first side face of the first lens is beneficial to ensuring the performance of the first lens in reducing aberration, improving image quality and overall optical characteristics, etc., and at the same time, it can also constrain the body length of the visual system to achieve miniaturization of the visual system.

[0067] In an exemplary embodiment, the spacer group may further include a third spacer, and the third spacer may be placed on the second side face of the third lens and at least partially in contact with the second side face of the third lens. The distance EP23 between the second spacer and the third spacer along the optical axis, the maximum thickness CP2 of the second spacer, and the central thickness CT3 of the third lens on the optical axis may satisfy: 1.65 < (CP2 + EP23) / CT3 < 2.1. By controlling the above conditional formula, the edge thicknesses of the second lens and the third lens can be constrained, improving the processability of the second lens and the third lens; at the same time, it is also beneficial to limit the ratio of the edge thickness to the central thickness of the third lens, thereby restricting the shape of the third lens and improving the processability of the third lens.

[0068] In an exemplary embodiment, the spacer group may further include a third spacer, and the third spacer may be placed on the second side face of the third lens and at least partially in contact with the second side face of the third lens. The effective focal length f3 of the third lens, the inner diameter d3s of the first side face of the third spacer, and the outer diameter D3s of the first side face of the third spacer may satisfy: -2.6 ≤ f3 / (d3s + D3s) < -1.7. Reasonably configuring the ratio of the effective focal length of the third lens to the sum of the inner and outer diameters of the first side face of the third spacer can constrain the effective focal length of the third lens, ensure that the aberration of the visual system is at an appropriate level, and is beneficial to the imaging of the visual system; at the same time, it can also limit the inner and outer diameters of the first side face of the third spacer, so that the third spacer effectively blocks the internal stray light generated by a part of the third lens, improving the imaging quality of the visual system.

[0069] In an exemplary embodiment, the spacer group may further include a third spacer, which may be disposed on the second side surface of the third lens and at least partially in contact with the second side surface of the third lens. The inner diameter d2m of the second side surface of the second spacer and the inner diameter d3m of the second side surface of the third spacer may satisfy: 1.5 < d2m / d3m < 1.85. Reasonably configuring the ratio of the inner diameter of the second side surface of the second spacer to the inner diameter of the second side surface of the third spacer is beneficial to restricting the assembly step difference between the second spacer and the second lens and the third lens, improving the assembly stability of the visual system, and making the distance from the inner diameter surface of the second spacer to the chief ray appropriate to avoid the primary stray light generated by the chief ray incident on the inner diameter surface of the second spacer; at the same time, it can also limit the inner diameter of the second side surface of the third spacer to ensure that the third spacer effectively intercepts part of the stray light generated at the positions of the first lens and the second lens, improving the imaging quality of the visual system.

[0070] In an exemplary embodiment, the spacer group may further include a third spacer, which may be disposed on the second side surface of the third lens and at least partially in contact with the second side surface of the third lens. The outer diameter D3m of the second side surface of the third spacer, the Abbe number V3 of the third lens, and the refractive index N3 of the third lens may satisfy: 1.5 mm < D3m / (V3 / N3) < 1.9 mm. By controlling the above conditional expression, the ratio of the Abbe number to the refractive index of the third lens can be restricted within a reasonable range, optimizing the dispersion characteristics of the visual system, improving the color reproduction ability and imaging quality of the visual system, and reducing the possible aberration in the visual system, reducing the distortion and blurring of the visual system; at the same time, it is also beneficial to limit the outer diameter of the third lens and improve the processability of the third lens.

[0071] In an exemplary embodiment, the spacer group may further include a third spacer, which may be disposed on the second side surface of the third lens and at least partially in contact with the second side surface of the third lens. The maximum thickness CP3 of the third spacer, the central thickness CTQ2 of the second quarter-wave plate on the optical axis, and the central thickness CTL of the polarizer on the optical axis satisfy: 0.15 < CP3 / (CTQ2 + CTL) < 0.6. By controlling the above conditional expression, it is beneficial to ensure that the central thicknesses of the second quarter-wave plate and the polarizer meet the requirements of forming and assembly attachment, reducing the assembly difficulty of the visual system; at the same time, it can also limit the edge thicknesses of the third lens and the fourth lens within a reasonable range, improving the processability of the third lens and the fourth lens.

[0072] The visual system according to the above embodiments 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 first quarter-wave plate, the second quarter-wave plate, the polarizer, 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 described above has characteristics such as miniaturization 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.

[0073] In the embodiments 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 astigmatism aberration. After using an aspherical lens, it is possible to eliminate as much as possible the aberration that appears during imaging, thereby improving the imaging quality.

[0074] However, those skilled in the art should understand that without departing from the technical solutions 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.

[0075] The second 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 disposed in the lens barrel. The optical element group includes a first lens with a positive optical power, a reflective polarizing element, a first quarter-wave plate, a second lens with a positive optical power, a third lens with a negative optical power, a partial reflection element, a second quarter-wave plate, a polarizer, and a fourth lens with a positive optical power arranged in sequence along the optical axis from the first side to the second side. The spacer group includes a first spacer and a second spacer. 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, and the second spacer is disposed on the second side surface of the second lens and is in contact with the second side surface of the second lens.

[0076] The distance EP12 between the first spacer and the second spacer along the optical axis and the on-axis distance T12 from the second side surface of the first lens to the first side surface of the second lens satisfy: 1.3 < EP12 / T12 < 3.8; the central thickness CTR of the reflective polarizing element on the optical axis, the central thickness CTQ1 of the first quarter-wave plate on the optical axis, the central thickness CT2 of the second lens on the optical axis, and the inner diameter d2s of the first side surface of the second spacer satisfy: 4.1 < d2s / (CTR + CTQ1 + CT2) < 7.2. The visual system provided in this application uses four lenses. By controlling the visual system to satisfy "1.3 < EP12 / T12 < 3.8" and "4.1 < d2s / (CTR + CTQ1 + CT2) < 7.2", the shapes of the first lens and the second lens can be restricted. While ensuring the optical performance of the visual system, the processability of the first lens and the second lens can be improved; at the same time, the body length of the visual system can also be restricted, realizing the compact design of the visual system, reducing the volume and weight of the device including the visual system, improving the wearing convenience of the device including the visual system, and making the inner diameter of the first side surface of the second spacer within a reasonable range, ensuring that there is sufficient bearing width between the second spacer and the second lens, avoiding stray light generated by the direct incidence of light on the inner diameter surface of the second spacer due to the too small inner diameter of the first side surface of the second spacer, and improving the imaging quality of the visual system.

[0077] The following further describes specific embodiments of the visual system applicable to the above embodiments with reference to the accompanying drawings.

[0078] Example 1

[0079] The following refers to Figure 2 Describe the visual system according to Embodiment 1 of the present application.

[0080] As Figure 2 shown, the visual system may include a lens barrel P0 and an optical element group and a spacer group disposed in the lens barrel P0.

[0081] The optical element group may include a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partial reflection element BS (not shown), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4 arranged in sequence along the optical axis from the first side to the second side. A diaphragm STO (not shown) may also be provided on the first side of the first lens E1. The spacer group may include a first spacer P1, a second spacer P2, and a third spacer P3. The first side surface of each element (for example, the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the first spacer P1, the second spacer P2, and the third spacer P3) is referred to as the near-eye side surface, and the second side surface is referred to as the near-screen side surface.

[0082] The first lens E1 has a positive focal power. Its side S1 close to the human eye is convex, and its side S2 close to the screen is concave. The second lens E2 has a positive focal power. Its side S3 close to the human eye is flat, and its side S4 close to the screen is convex. The third lens E3 has a negative focal power. Its side S5 close to the human eye is concave, and its side S6 close to the screen is convex. The fourth lens E4 has a positive focal power. Its side S7 close to the human eye is flat, and its side S8 close to the screen is convex. The reflective polarizing element RP and the first quarter-wave plate QWP1 are attached to the side S3 of the second lens E2 close to the human eye. The partial reflection element BS is attached to the side S6 of the third lens E3 close to the screen. The second quarter-wave plate QWP2 and the polarizer LP are attached to the side S7 of the fourth lens E4 close to the human eye. It should be noted that the surfaces S1 - S8 are not shown in Figure 2 this figure.

[0083] In this example, an image plane IMG (not shown) can be provided on the second side of the visual system. The image plane IMG can be provided with a display screen, for example. The image light from the image plane IMG sequentially passes through the fourth lens E4, the polarizer LP, the second quarter-wave plate QWP2, the third lens E3, the second lens E2, the first quarter-wave plate QWP1 and reaches the reflective polarizing element RP, where the first reflection occurs. The light after the first reflection passes through the first quarter-wave plate QWP1, the second lens E2, the third lens E3 and reaches the partial reflection element BS located on the side S6 of the third lens E3 close to the screen, where the second reflection occurs. The light after the second reflection sequentially passes through the third lens E3, the second lens E2, the first quarter-wave plate QWP1, the reflective polarizing element RP, the first lens E1 to the aperture stop and finally projects onto the user's eye. For example, the light after two reflections of this visual system finally projects onto the user's eye. A protective glass E5 can also be provided between the image plane IMG and the fourth lens E4.

[0084] Table 1 shows the basic parameter table of the visual system in Embodiment 1. Among them, the unit of the radius of curvature and the thickness / distance is millimeter (mm). The image light from the image plane IMG passes through each element in the order from No. 23 to No. 1 and finally projects onto the user's eye.

[0085]

[0086] Table 1

[0087] In this embodiment, the side S5 of the third lens E3 close to the human eye, the side S6 close to the screen, and the side S8 of the fourth lens E4 close to the screen are all aspherical surfaces. The surface profile x of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0088]

[0089] Wherein, x is the sagitta, the distance from the vertex of the aspheric surface to the aspheric surface at a position with 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 radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the correction coefficient of the i-th order of the aspheric surface. Table 2 gives the higher-order term coefficients A4, A6, A8, A 10 , A 12 , A 14 , A 16 , A 18 and A 20 .

[0090] Surface number A4 A6 A8 A10 A12 A14 A16 A18 A20 S5 -4.3410E-01 1.1114E-01 -4.1613E-02 -2.5404E-04 3.3580E-03 1.8738E-03 4.9089E-04 0.0000E+00 0.0000E+00 S6 3.8184E-01 1.5502E-01 1.8114E-02 4.7055E-03 4.4412E-04 -3.0054E-05 1.8337E-06 0.0000E+00 0.0000E+00 S8 -1.2977E-01 2.3621E-02 -1.3190E-03 -1.4779E-04 1.3903E-04 -1.7295E-04 -7.2783E-05 0.0000E+00 0.0000E+00

[0091] Table 2

[0092] Example 2

[0093] The following refers to Figure 3 Describe the visual system according to Embodiment 2 of the present application.

[0094] As Figure 3 shown, the visual system may include a lens barrel P0 and an optical element group and a spacer group disposed within the lens barrel P0.

[0095] The optical element group may include a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partially reflective element BS (not shown), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4 arranged in sequence along the optical axis from the first side to the second side. A stop STO (not shown) may also be provided on the first side of the first lens E1. An image plane IMG (not shown) may be provided on the second side of the visual system, and a protective glass E5 may also be provided between the image plane IMG and the fourth lens E4. The spacer group may include a first spacer P1, a second spacer P2, and a third spacer P3.

[0096] The structure of the optical element group in this embodiment is the same as that of the optical element group in Embodiment 1, that is, the basic parameter table of the visual system in 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 of the elements in the lens barrel P0 and the spacer group are different.

[0097] Example 3

[0098] The following refers to Figure 4 Describe the visual system according to Embodiment 3 of the present application.

[0099] AsFigure 4 As shown, the visual system may include a lens barrel P0, and an optical element group and a spacer group disposed within the lens barrel P0.

[0100] The optical element group may include a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partial reflection element BS (not shown), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4 arranged in sequence along the optical axis from the first side to the second side. A stop STO (not shown) may also be provided on the first side of the first lens E1. An image plane IMG (not shown) may be provided on the second side of the visual system, and a protective glass E5 may also be provided between the image plane IMG and the fourth lens E4. The spacer group may include a first spacer P1, a second spacer P2, and a third spacer P3.

[0101] The structure of the optical element group in this embodiment is the same as that of the optical element group in Embodiment 1, that is, the basic parameter table of the visual system in 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 of the elements in the lens barrel P0 and the spacer group are different.

[0102] Figure 5A The axial chromatic aberration curve of the visual system of Embodiment 1, 2, or 3 is shown, which represents the deviation of the convergence points of light rays of different wavelengths after passing through the visual system. Figure 5B The astigmatism curve of the visual system of Embodiment 1, 2, or 3 is shown, which represents 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 represents the distortion magnitude values corresponding to different field angles. Figure 5D The modulation transfer function curve of the visual system of Embodiment 1, 2, or 3 is shown. According to Figures 5A to 5D It can be known that the visual systems given in Embodiment 1, 2, or 3 can achieve good imaging quality.

[0103] Example 4

[0104] The following refers to Figure 6 Describe the visual system according to Embodiment 4 of the present application.

[0105] As Figure 6 shown, the visual system may include a lens barrel P0, and an optical element group and a spacer group disposed within the lens barrel P0.

[0106] The optical element group may include a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partial reflection element BS (not shown), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4 arranged in sequence along the optical axis from the first side to the second side. An aperture STO (not shown) may also be provided on the first side of the first lens E1. The spacer group may include a first spacer P1, a second spacer P2, and a third spacer P3. The first side surfaces of each element (e.g., the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the first spacer P1, the second spacer P2, and the third spacer P3) are all referred to as the near-eye side surfaces, and the second side surfaces are all referred to as the near-screen side surfaces.

[0107] The first lens E1 has a positive optical power, its near-eye side surface S1 is convex, and its near-screen side surface S2 is concave. The second lens E2 has a positive optical power, its near-eye side surface S3 is flat, and its near-screen side surface S4 is convex. The third lens E3 has a negative optical power, its near-eye side surface S5 is concave, and its near-screen side surface S6 is convex. The fourth lens E4 has a positive optical power, its near-eye side surface S7 is flat, and its near-screen side surface S8 is convex. The reflective polarizing element RP and the first quarter-wave plate QWP1 are attached to the near-eye side surface S3 of the second lens E2. The partial reflection element BS is attached to the near-screen side surface S6 of the third lens E3. The second quarter-wave plate QWP2 and the polarizer LP are attached to the near-eye side surface S7 of the fourth lens E4. It should be noted that the surfaces S1 - S8 are not shown in Figure 6 this figure.

[0108] In this example, an image plane IMG (not shown) may be provided on the second side of the visual system, and the image plane IMG may be provided with a display screen, for example. The image light from the image plane IMG sequentially passes through the fourth lens E4, the polarizer LP, the second quarter-wave plate QWP2, the third lens E3, the second lens E2, the first quarter-wave plate QWP1 and reaches the reflective polarizing element RP, where the first reflection occurs. The light after the first reflection passes through the first quarter-wave plate QWP1, the second lens E2, the third lens E3 and reaches the partial reflection element BS located on the near-screen side surface of the third lens E3, where the second reflection occurs. The light after the second reflection sequentially passes through the third lens E3, the second lens E2, the first quarter-wave plate QWP1, the reflective polarizing element RP, the first lens E1 to the aperture and finally projects onto the user's eyes. For example, the light of the visual system after two reflections finally projects onto the user's eyes. A protective glass E5 may also be provided between the image plane IMG and the fourth lens E4.

[0109] Table 3 shows the basic parameter table of the visual system of Example 4. Among them, the units of the radius of curvature and the thickness / distance are both millimeters (mm). The image light from the image plane IMG passes through each element in the order from No. 23 to No. 1 and is finally projected onto the user's eyes.

[0110]

[0111] Table 3

[0112] In this embodiment, the near-screen side S4 of the second lens E2, the near-eye side S5 and the near-screen side S6 of the third lens E3, and the near-screen side S8 of the fourth lens E4 are all aspherical surfaces. Table 4 gives the higher-order coefficients A4, A6, A8, A 10 、A 12 、A 14 、A 16 、A 18 and A 20 .

[0113]

[0114]

[0115] Table 4

[0116] Example 5

[0117] The following refers to Figure 7 to describe the visual system according to Embodiment 5 of the present application.

[0118] As Figure 7 shown, the visual system may include a lens barrel P0 and an optical element group and a spacer group disposed within the lens barrel P0.

[0119] The optical element group may include a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partially reflective element BS (not shown), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4 arranged in sequence along the optical axis from the first side to the second side. A diaphragm STO (not shown) may also be provided on the first side of the first lens E1. An image plane IMG (not shown) may be provided on the second side of the visual system, and a protective glass E5 may also be provided between the image plane IMG and the fourth lens E4. The spacer group may include a first spacer P1, a second spacer P2, and a third spacer P3.

[0120] The structure of the optical element group in this embodiment is the same as that of the optical element group in Embodiment 4, that is, the basic parameter table of the visual system in this embodiment is the same as Table 3, and the aspherical coefficient table is the same as Table 4. The difference between this embodiment and Embodiment 4 lies in that the structural dimensions of at least some elements in the lens barrel P0 and the spacer group are different.

[0121] Example 6

[0122] The following refers to Figure 8 Describe the visual system according to Embodiment 6 of the present application.

[0123] As Figure 8 shown, the visual system may include a lens barrel P0 and an optical element group and a spacer group disposed within the lens barrel P0.

[0124] The optical element group may include a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partially reflective element BS (not shown), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4 arranged in sequence along the optical axis from the first side to the second side. A stop STO (not shown) may also be provided on the first side of the first lens E1. An image plane IMG (not shown) may be provided on the second side of the visual system, and a protective glass E5 may also be provided between the image plane IMG and the fourth lens E4. The spacer group may include a first spacer P1, a second spacer P2, and a third spacer P3.

[0125] The structure of the optical element group in this embodiment is the same as that of the optical element group in Embodiment 4, that is, the basic parameter table of the visual system in this embodiment is the same as Table 3, and the aspherical coefficient table is the same as Table 4. The difference between this embodiment and Embodiment 4 lies in that the structural dimensions of at least some elements in the lens barrel P0 and the spacer group are different.

[0126] Figure 9A shows the axial chromatic aberration curve of the visual system of Embodiment 4, 5 or 6, which represents the deviation of the convergence points of light rays of different wavelengths after passing through the visual system. Figure 9B shows the astigmatism curve of the visual system of Embodiment 4, 5 or 6, which represents the meridional image plane curvature and sagittal image plane curvature corresponding to different field angles. Figure 9C shows the distortion curve of the visual system of Embodiment 4, 5 or 6, which represents the distortion magnitude values corresponding to different field angles. Figure 9D shows the modulation transfer function curve of the visual system of Embodiment 4, 5 or 6. According to Figures 9A to 9D it can be known that the visual systems given in Embodiment 4, 5 or 6 can achieve good imaging quality.

[0127] Example 7

[0128] The following refers to Figure 10 a visual system according to Embodiment 7 of the present application.

[0129] As Figure 10 shown, the visual system may include a lens barrel P0 and an optical element group and a spacer group disposed within the lens barrel P0.

[0130] The optical element group may include a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partial reflection element BS (not shown), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4 arranged in sequence along the optical axis from the first side to the second side. A stop STO (not shown) may also be provided on the first side of the first lens E1. The spacer group may include a first spacer P1, a second spacer P2, and a third spacer P3. The first side surface of each element (for example, the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the first spacer P1, the second spacer P2, and the third spacer P3) is referred to as the near-eye side surface, and the second side surface is referred to as the near-screen side surface.

[0131] The first lens E1 has a positive optical power, its near-eye side surface S1 is convex, and its near-screen side surface S2 is concave. The second lens E2 has a positive optical power, its near-eye side surface S3 is flat, and its near-screen side surface S4 is convex. The third lens E3 has a negative optical power, its near-eye side surface S5 is concave, and its near-screen side surface S6 is convex. The fourth lens E4 has a positive optical power, its near-eye side surface S7 is flat, and its near-screen side surface S8 is convex. The reflective polarizing element RP and the first quarter-wave plate QWP1 are attached to the near-eye side surface S3 of the second lens E2. The partial reflection element BS is attached to the near-screen side surface S6 of the third lens E3. The second quarter-wave plate QWP2 and the polarizer LP are attached to the near-eye side surface S7 of the fourth lens E4. It should be noted that the surfaces S1 - S8 are not shown in Figure 10 this figure.

[0132] In this example, the second side of the visual system may be provided with an image surface IMG (not shown), and the image surface IMG may be provided with a display screen, for example. The image light from the image surface IMG sequentially passes through the fourth lens E4, the polarizer LP, the second quarter-wave plate QWP2, the third lens E3, the second lens E2, the first quarter-wave plate QWP1 and reaches the reflective polarizing element RP, where the first reflection occurs. The light reflected for the first time passes through the first quarter-wave plate QWP1, the second lens E2, the third lens E3 and reaches the partial reflection element BS on the near-screen side of the third lens E3, where the second reflection occurs. The light reflected for the second time sequentially passes through the third lens E3, the second lens E2, the first quarter-wave plate QWP1, the reflective polarizing element RP, the first lens E1 to the aperture stop and finally projects onto the user's eyes. For example, the light of the visual system after two reflections finally projects onto the user's eyes. A protective glass E5 may also be provided between the image surface IMG and the fourth lens E4.

[0133] Table 5 shows the basic parameter table of the visual system of Embodiment 7, where the unit of the radius of curvature and the thickness / distance is millimeter (mm). The image light from the image surface IMG passes through each element in the order from No. 23 to No. 1 and finally projects onto the user's eyes.

[0134]

[0135]

[0136] Table 5

[0137] In this embodiment, the near-eye side S5 and the near-screen side S6 of the third lens E3, and the near-screen side S8 of the fourth lens E4 are all aspherical surfaces. Table 6 gives the higher-order term coefficients A4, A6, A8, A 10 、A 12 、A 14 、A 16 、A 18 and A 20 .

[0138] Surface number A4 A6 A8 A10 A12 A14 A16 A18 A20 S5 -1.2655E+00 -6.7949E-01 -5.3222E-01 -2.6516E-01 -1.0177E-01 -2.6735E-02 -3.6799E-03 0.0000E+00 0.0000E+00 S6 -3.7357E-01 -5.0463E-01 -3.8787E-01 -1.9594E-01 -7.2611E-02 -1.8009E-02 -2.3212E-03 0.0000E+00 0.0000E+00 S8 -6.1539E-02 1.5299E-02 1.8727E-03 -6.5188E-04 4.1568E-04 -1.2510E-04 1.3397E-04 0.0000E+00 0.0000E+00

[0139] Table 6

[0140] Example 8

[0141] The following refers to Figure 11 to describe the visual system according to Embodiment 8 of the present application.

[0142] As Figure 11As shown, the visual system may include a barrel P0, and an optical element group and a spacer group disposed within the barrel P0.

[0143] The optical element group may include a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partially reflective element BS (not shown), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4 arranged in sequence along the optical axis from the first side to the second side. An aperture STO (not shown) may also be provided on the first side of the first lens E1. An image plane IMG (not shown) may be provided on the second side of the visual system, and a protective glass E5 may also be provided between the image plane IMG and the fourth lens E4. 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 in this embodiment is the same as that of the optical element group in Embodiment 7, that is, the basic parameter table of the visual system in this embodiment is the same as Table 5, and the aspherical coefficient table is the same as Table 6. The difference between this embodiment and Embodiment 7 lies in that the structural dimensions of at least some of the elements in the barrel P0 and the spacer group are different.

[0145] Example 9

[0146] The following refers to Figure 12 Describe the visual system according to Embodiment 9 of the present application.

[0147] As Figure 12 As shown, the visual system may include a barrel P0, and an optical element group and a spacer group disposed within the barrel P0.

[0148] The optical element group may include a first lens E1, a reflective polarizing element RP, a first quarter-wave plate QWP1, a second lens E2, a third lens E3, a partially reflective element BS (not shown), a second quarter-wave plate QWP2, a polarizer LP, and a fourth lens E4 arranged in sequence along the optical axis from the first side to the second side. An aperture STO (not shown) may also be provided on the first side of the first lens E1. An image plane IMG (not shown) may be provided on the second side of the visual system, and a protective glass E5 may also be provided between the image plane IMG and the fourth lens E4. The spacer group may include a first spacer P1, a second spacer P2, and a third spacer P3.

[0149] The structure of the optical element group in this embodiment is the same as that of the optical element group in Embodiment 7, that is, the basic parameter table of the visual system in this embodiment is the same as Table 5, and the aspherical coefficient table is the same as Table 6. The difference between this embodiment and Embodiment 7 lies in that the structural dimensions of at least some of the elements in the barrel P0 and the spacer group are different.

[0150] Figure 13A The axial chromatic aberration curve of the visual system of Embodiment 7, 8 or 9 is shown, which represents the deviation of the convergence points of light rays of different wavelengths after passing through the visual system. Figure 13B The astigmatism curve of the visual system of Embodiment 7, 8 or 9 is shown, which represents the meridional image plane curvature and sagittal image plane curvature corresponding to different field angles of view. Figure 13C The distortion curve of the visual system of Embodiment 7, 8 or 9 is shown, which represents the distortion magnitude values corresponding to different field angles of view. Figure 13D The modulation transfer function curve of the visual system of Embodiment 7, 8 or 9 is shown. According to Figures 13A to 13D it can be known that the visual system given in Embodiment 7, 8 or 9 can achieve good imaging quality.

[0151] Table 7 gives the values of parameters such as f, f1, f2, f3, f4, fz1, EPD, TD, etc. for each of the embodiments in Embodiments 1-9. Among them, the units of f, f1, f2, f3, f4, fz1, EPD, TD in Table 7 are all millimeters (mm).

[0152] Parameter / Example 1 2 3 4 5 6 7 8 9 f 42.00 42.00 42.00 42.00 42.00 42.00 42.00 42.00 42.00 f1 51.92 51.92 51.92 60.00 60.00 60.00 48.81 48.81 48.81 f2 157.39 157.39 157.39 132.00 132.00 132.00 107.94 107.94 107.94 f3 -105.99 -105.99 -105.99 -119.99 -119.99 -119.99 -84.16 -84.16 -84.16 f4 151.27 151.27 151.27 1087.86 1087.86 1087.86 699419.05 699419.05 699419.05 fz1 157.39 157.39 157.39 132.00 132.00 132.00 107.94 107.94 107.94 EPD 23.00 23.00 23.00 23.00 23.00 23.00 23.00 23.00 23.00 TD 25.39 25.39 25.39 25.39 25.39 25.39 25.39 25.39 25.39

[0153] Table 7

[0154] Table 8 gives the values of parameters such as d1s, d1m, D1s, D1m, d2s, d2m, D2s, D2m, d3s, d3m, D3s, D3m, d0s, d0m, D0s, D0m, EP01, CP1, EP12, CP2, EP23, CP3 and L for each of the embodiments in Embodiments 1-9. Among them, at least some of the above parameters can be measured according to Figure 1 the marking method shown, and the units of the parameters listed in Table 8 are all millimeters (mm).

[0155] Parameter / Example 1 2 3 4 5 6 7 8 9 d1s 27.059 27.812 27.361 27.137 27.137 27.137 26.557 26.742 27.613 d1m 27.059 27.812 27.361 27.137 27.137 27.137 26.557 26.742 27.613 D1s 38.599 35.599 33.599 38.599 36.045 36.045 38.599 35.199 33.962 D1m 38.599 35.599 33.599 38.599 36.045 36.045 38.599 35.199 33.962 d2s 27.034 26.445 26.445 27.613 26.564 26.564 26.668 25.012 25.012 d2m 25.236 23.651 23.332 26.106 24.283 24.283 24.420 25.798 25.012 D2s 32.872 30.872 29.494 35.444 30.896 30.896 35.444 32.044 33.152 D2m 31.075 31.194 27.826 34.908 29.864 29.864 36.277 32.235 33.152 d3s 14.133 15.471 14.076 14.509 14.509 15.926 14.509 14.509 16.414 d3m 14.133 15.471 14.076 14.509 14.509 15.926 14.509 14.509 16.414 D3s 33.706 31.706 28.978 33.706 31.706 30.553 33.706 31.306 30.687 D3m 33.706 31.706 28.978 33.706 31.706 30.553 33.706 31.306 30.687 d0s 41.682 38.682 36.682 41.682 38.814 38.814 41.682 38.282 37.045 d0m 17.364 16.835 16.835 18.816 18.816 16.949 18.816 18.816 16.963 D0s 44.162 41.162 39.162 44.162 41.294 41.294 44.162 40.362 39.125 D0m 37.803 34.803 28.832 37.656 33.656 33.656 37.656 32.730 27.079 EP01 8.434 7.934 9.934 7.833 8.843 8.843 7.964 7.784 9.555 CP1 0.068 0.068 0.068 0.068 0.058 0.058 0.068 0.048 0.048 EP12 3.537 3.737 3.737 2.559 2.659 2.659 4.604 4.900 4.900 CP2 4.621 4.621 4.648 5.625 5.575 5.575 3.191 3.410 0.105 EP23 7.730 7.580 7.653 8.552 8.552 8.547 8.851 8.437 11.642 CP3 0.150 0.100 0.100 0.150 0.100 0.105 0.150 0.050 0.100 L 29.014 28.114 30.114 29.261 30.261 30.261 29.261 29.061 30.632

[0156] Table 8 Table 9 shows the values of the conditional expressions for each of the embodiments in Embodiments 1-9.

[0157]

[0158]

[0159] Table 9

[0160] This application also provides an optical device, which can be an independent projection device such as a projector, or a projection module integrated on 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 applied. 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 the 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 technical solution formed by mutually replacing the above features with (but not limited to) the technical features with similar functions disclosed in the present application.

Claims

1. A visual system, characterized in that: include: An optical element group, comprising a first lens with positive power, a reflective polarizing element, a first quarter wave plate, a second lens with positive power, a third lens with negative power, a partial reflective element, a second quarter wave plate, a polarizing plate, and a fourth lens with positive power, which are arranged in sequence from a first side to a second side along an optical axis; a spacer set, comprising a first spacer and a second spacer, wherein the first spacer is disposed on the second side of the first lens and contacts the second side of the first lens, and the second spacer is disposed on the second side of the second lens and contacts the second side of the second lens; as well as A lens barrel, wherein the optical element group and the spacer group are placed in the lens barrel; Wherein, the number of lenses with optical power in the visual system is four; A distance EP12 between the first spacer and the second spacer along the optical axis and an axial distance T12 from the second side surface of the first lens to the first side surface of the second lens satisfy: 1.36≤EP12 / T12<3.8; A distance EP01 between the first side end surface of the lens barrel and the first spacer along the optical axis, a maximum thickness CP1 of the first spacer, and a center thickness CT1 of the first lens on the optical axis satisfy: 1.3<(EP01+CP1) / CT1<1.

75.

2. The visual system according to claim 1, characterized in that: The effective focal length f1 of the first lens and the outer diameter D1s of the first side surface of the first spacer satisfy the following: 1.26≤f1 / D1s<1.

7.

3. The visual system according to claim 1, characterized in that: The combined focal length fz1 of the reflective polarizing element, the first quarter-wave plate and the second lens, the inner diameter d1m of the second side of the first spacer and the outer diameter D1m of the second side of the first spacer satisfy: 1.66≤fz1 / (d1m+D1m)<2.

6.

4. The visual system according to claim 1, characterized in that: The curvature radius R2 of the second side surface of the first lens and the inner diameter d1s of the first side surface of the first spacer satisfy: 2.15 <R2 / d1s<3.4。 5. The visual system according to claim 1, characterized in that: The center thickness CTR of the reflective polarizing element on the optical axis, the center thickness CTQ1 of the first quarter wave plate on the optical axis, the center thickness CT2 of the second lens on the optical axis and the inner diameter d2s of the first side surface of the second spacer satisfy: 4.1 <d2s / (CTR+CTQ1+CT2)<7.2。 6. The visual system according to claim 1, characterized in that: An inner diameter d0m of the second side end surface of the lens barrel, an outer diameter D0m of the second side end surface of the lens barrel, and a length L of the lens barrel along the direction of the optical axis satisfy the following: 0.3<(D0m-d0m) / L<0.

75.

7. The visual system according to claim 1, characterized in that: An outer diameter D0s of the first side end surface of the lens barrel and an entrance pupil diameter EPD of the visual system satisfy the following: 1.7≤D0s / EPD<1.

95.

8. The visual system according to claim 1, characterized in that: An outer diameter D2s of the first side surface of the second spacer, an outer diameter D2m of the second side surface of the second spacer, and a total effective focal length f of the visual system satisfy the following: 1.35<(D2s+D2m) / f<1.

75.

9. 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 axial distance TD from the first side surface of the first lens to the second side surface of the fourth lens satisfy: 1.4 <d0s / TD≤1.64。 10. The visual system according to claim 1, characterized in that: The length L of the lens barrel along the direction of the optical axis and the curvature radius R1 of the first side surface of the first lens satisfy: 1.4 <L / R1<1.6。 11. The visual system according to any one of claims 1 to 10, characterized in that: The spacer set further includes a third spacer, the third spacer being disposed on the second side surface of the third lens and in contact with the second side surface of the third lens; The distance EP23 between the second spacer and the third spacer along the optical axis, the maximum thickness CP2 of the second spacer, and the center thickness CT3 of the third lens on the optical axis satisfy: 1.65<(CP2+EP23) / CT3≤2.

03.

12. The visual system according to any one of claims 1 to 10, characterized in that: The spacer set further includes a third spacer, the third spacer being disposed on the second side surface of the third lens and in contact with the second side surface of the third lens; The effective focal length f3 of the third lens, the inner diameter d3s of the first side surface of the third spacer, and the outer diameter D3s of the first side surface of the third spacer satisfy: -2.6≤f3 / (d3s+D3s)<-1.

7.

13. The visual system according to any one of claims 1 to 10, characterized in that: The spacer set further includes a third spacer, the third spacer being disposed on the second side surface of the third lens and in contact with the second side surface of the third lens; The inner diameter d2m of the second side surface of the second spacer and the inner diameter d3m of the second side surface of the third spacer satisfy: 1.5 <d2m / d3m<1.85。 14. The visual system according to any one of claims 1 to 10, characterized in that: The spacer set further includes a third spacer, the third spacer being disposed on the second side surface of the third lens and in contact with the second side surface of the third lens; The outer diameter D3m of the second side surface of the third spacer, the Abbe number V3 of the third lens and the refractive index N3 of the third lens satisfy: 1.5 mm <D3m / (V3 / N3)≤1.84mm。 15. The visual system according to any one of claims 1 to 10, characterized in that: The spacer set further includes a third spacer, the third spacer being disposed on the second side surface of the third lens and in contact with the second side surface of the third lens; Wherein, the maximum thickness CP3 of the third spacer, the center thickness CTQ2 of the second quarter wave plate on the optical axis and the center thickness CTL of the polarizer on the optical axis satisfy: 0.15 <CP3 / (CTQ2+CTL)<0.6。 16. The visual system according to any one of claims 1 to 10, characterized in that: The first side surface of the first lens is a convex surface, and the second side surface is a concave surface; The first side surface of the second lens is a plane surface, and the second side surface is a convex surface; The first side surface of the third lens is a concave surface, and the second side surface is a convex surface; The first side surface of the fourth lens is a plane, and the second side surface is a convex surface.

Images