visual system

Abstract

The present invention provides a visual system. The visual system includes a lens barrel, a lens assembly, and a spacer element assembly disposed therein. The lens assembly comprises four lenses, a polarizer, a reflective polarizer, a quarter-wave plate, and a reflective element, satisfying the following conditions: 1.72 ≤ fz / (D1s + D1m) ≤ 2.54; and 2.71 ≤ TD / (EP13 + CP3) ≤ 3.17. The present invention addresses the problem of prior art four-lens visual systems, which, due to the rational arrangement of cemented lenses and folding elements to meet the requirements of lightweight and thinness, result in improper lens aperture design and severe stray light.

Description

Technical Field

[0001] The present invention relates to the technical field of optical imaging equipment, and in particular to a visual system. Background Art

[0002] In recent years, VR devices featuring human-computer interaction have become increasingly popular, and market demand continues to grow. As a key component of VR devices, the performance of the visual system directly impacts the user's visual experience and the device's overall performance. Four-lens visual systems are widely used in various VR devices due to their minimal lens count and simple structure.

[0003] Currently, four-element vision systems, to meet the demand for thinness and lightness, utilize a rational arrangement of cemented lenses and folding elements to reduce the overall length of the vision system. However, the design of the lens aperture has certain limitations. Improper lens aperture design, influenced by lens size, can cause the light in the vision system to undergo multiple reflections and scattering, easily generating new stray light. This stray light can create ghost images in the image, seriously affecting the image quality of the vision system.

[0004] That is to say, the four-piece vision system in the prior art has the problem of improper lens aperture design due to the reasonable arrangement of cemented lenses and folding elements to meet the demand for lightness and thinness, resulting in serious stray light problems. Summary of the Invention

[0005] The main purpose of the present invention is to provide a visual system to solve the problem of the four-piece visual system in the prior art that the lens aperture is improperly designed to meet the demand for lightness and thinness by reasonably arranging the glued lens and the return element, resulting in serious stray light.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a visual system is provided, comprising a lens barrel and a lens group and a spacer element group arranged in the lens barrel, wherein the lens group consists of four lenses, a polarizer, a reflective polarizing element, a quarter-wave plate and a reflective element, and the four lenses are, from the first side to the second side, a first lens with positive focal power, a second lens with negative focal power, a third lens with positive focal power or negative focal power and a fourth lens with positive focal power, the first side surface of the first lens is concave, and the second side surface is convex; the first side surface of the second lens is concave, and the second side surface is convex; the first side surface of the third lens is concave, and the second side surface is convex; the first side surface of the fourth lens is concave, and the second side surface is convex; the second lens and the third lens are cemented to form a cemented lens; the polarizer, the reflective polarizing element and the quarter-wave plate are arranged between the first lens and the second lens and along a direction away from the first lens The reflective element is arranged in sequence; the third lens is arranged between the fourth lens; the spacer element group includes a first spacer element located between the first lens and the second lens and supported by the second side surface of the first lens, and a third spacer element located between the third lens and the fourth lens and supported by the second side surface of the third lens; the combined focal length fz of the first lens, the polarizer, the reflective polarizing element and the quarter-wave plate, the outer diameter D1s of the first side surface of the first spacer element and the outer diameter D1m of the second side surface of the first spacer element satisfy: 1.72≤fz / (D1s+D1m)≤2.54; the axial distance TD from the first side surface of the first lens to the second side surface of the fourth lens, the axial spacing EP13 from the second side surface of the first spacer element to the first side surface of the third spacer element and the maximum axial thickness CP3 of the third spacer element satisfy: 2.71≤TD / (EP13+CP3)≤3.17.

[0007] According to another aspect of the present invention, a visual system is provided, comprising a lens barrel and a lens group and a spacer element group arranged in the lens barrel, wherein the lens group is composed of four lenses, a polarizing plate, a reflective polarizing element, a quarter-wave plate and a reflective element, wherein the four lenses are, from the first side to the second side, a first lens with positive focal power, a second lens with negative focal power, a third lens with positive focal power or negative focal power and a fourth lens with positive focal power, wherein the first side surface of the first lens is concave and the second side surface is convex; the first side surface of the second lens is concave and the second side surface is convex; the first side surface of the third lens is concave and the second side surface is convex; the first side surface of the fourth lens is concave and the second side surface is convex; the second lens and the third lens are cemented to form a cemented lens; the polarizing plate, the reflective polarizing element and the quarter-wave plate are arranged The reflective element is arranged in sequence between the first lens and the second lens and in a direction away from the first lens; the reflective element is arranged between the third lens and the fourth lens; the spacer element group includes a first spacer element located between the first lens and the second lens and supporting the second side surface of the first lens, and a third spacer element located between the third lens and the fourth lens and supporting the second side surface of the third lens; the combined focal length fz of the first lens, the polarizer, the reflective polarizing element and the quarter-wave plate, the outer diameter D1s of the first side surface of the first spacer element and the outer diameter D1m of the second side surface of the first spacer element satisfy the following: 1.72≤fz / (D1s+D1m)≤2.54; the effective focal length f4 of the fourth lens and the inner diameter d3m of the second side surface of the third spacer element satisfy the following: 1.81≤f4 / d3m≤8.26.

[0008] Furthermore, the axial spacing EP01 from the first side surface of the lens barrel to the first side surface of the first spacing element, the curvature radius R1 of the first side surface of the first lens, and the curvature radius R2 of the second side surface of the first lens satisfy: 6.03mm≤EP01×(R1 / R2)≤8.88mm.

[0009] Furthermore, the effective focal length f1 of the first lens and the outer diameter D0s of the first side surface of the lens barrel satisfy the following relationship: 3.12≤f1 / D0s≤4.61.

[0010] Furthermore, an inner diameter d1m of the second side surface of the first spacer element 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 the following relationship: 11.23≤d1m / T12≤15.17.

[0011] Furthermore, an inner diameter d3s of the first side surface of the third spacer element and a curvature radius R6 of the second side surface of the third lens satisfy: -1.34≤d3s / R6≤-1.19.

[0012] Furthermore, the combined focal length f23 of the second lens and the third lens, the outer diameter D3s of the first side surface of the third spacer element, and the outer diameter D3m of the second side surface of the third spacer element satisfy: -4.84≤f23 / (D3s+D3m)≤-4.45.

[0013] Furthermore, an inner diameter d0m of the second side surface of the lens barrel and a curvature radius R8 of the second side surface of the fourth lens satisfy the relationship: -2.79≤d0m / R8≤-1.78.

[0014] Furthermore, an effective focal length f4 of the fourth lens and an inner diameter d3m of the second side surface of the third spacer element satisfy the relationship: 1.81≤f4 / d3m≤8.26.

[0015] Furthermore, the inner diameter d0s of the first side surface of the lens barrel and the entrance pupil diameter EPD of the visual system satisfy the following relationship: 9.67≤d0s / EPD≤10.91.

[0016] Furthermore, the on-axis spacing EP13 from the second side surface of the first spacing element to the first side surface of the third spacing element, the effective focal length f2 of the second lens, and the effective focal length f3 of the third lens satisfy: 2.35 mm ≤ EP13 × | f2 / f3 | ≤ 12.56 mm.

[0017] Furthermore, the axial spacing EP01 from the first side surface of the lens barrel to the first side surface of the first spacing element, the maximum axial thickness CP1 of the first spacing element, and the center thickness CT1 of the first lens on the optical axis of the visual system satisfy: 1.22≤(EP01+CP1) / CT1≤1.64.

[0018] Furthermore, an outer diameter D0m of the second side surface of the lens barrel and an effective focal length f of the visual system satisfy the following relationship: 2.02≤D0m / f≤2.45.

[0019] Furthermore, the inner diameter d1s of the first side surface of the first spacing element and the axial distance L from the first side surface to the second side surface of the lens barrel satisfy the following relationship: 1.72≤d1s / L≤2.16.

[0020] Furthermore, the inner diameter d3s of the first side surface of the third spacer element, the inner diameter d1s of the first side surface of the first spacer element, the center thickness CT2 of the second lens on the optical axis of the visual system, and the center thickness CT3 of the third lens on the optical axis satisfy the following relationship: 2.12≤(d3s-d1s) / (CT2+CT3)≤2.96.

[0021] Applying the technical solution of the present invention, the visual system of the present application is composed of a lens barrel and four lenses arranged in the lens barrel, multiple spacer elements, a polarizer, a reflective polarizer, a quarter-wave plate, and a reflective element. By reasonably setting the optical power and surface shape of each lens, the positions of the first spacer element, the third spacer element, the polarizer, the reflective polarizer, the quarter-wave plate, and the reflective element, and arranging the second lens and the third lens to form a cemented lens, it is beneficial to compress the distance between the second lens and the third lens. At the same time, the light path is planned to be refracted and reflected between the first lens and the second lens, and between the third lens and the fourth lens, which is beneficial to folding the light path, achieving compression of the total optical length, and facilitating the realization of lightweight and thinness. However, in this case, due to the influence of the lens size, the light in the visual system is reflected and scattered multiple times, forming new stray light. Therefore, this application further increases the aperture of each lens while ensuring optical performance by constraining 1.72≤fz / (D1s+D1m)≤2.54 and 2.71≤TD / (EP13+CP3)≤3.17, thereby reducing the theoretical vignetting phenomenon and improving the uniformity of light intensity within the visual range; at the same time, it ensures the rationality of the lens aperture design and reduces the risk of stray light ghost images caused by improper lens aperture design. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 A dimensioned diagram illustrating a visual system according to an alternative embodiment of the present invention;

[0024] Figure 2 A schematic structural diagram of a visual system according to embodiment 1-1 of the present invention is shown;

[0025] Figure 3 A schematic structural diagram of a visual system according to Embodiment 1-2 of the present invention is shown;

[0026] Figure 4 Schematic diagrams showing the structures of the visual systems of Examples 1-3 of the present invention;

[0027] Figure 5 FIG2 shows an MTF curve diagram of the visual system according to the first embodiment of the present invention;

[0028] Figure 6 A schematic structural diagram of a visual system according to embodiment 2-1 of the present invention is shown;

[0029] Figure 7 A schematic structural diagram of a visual system according to embodiment 2-2 of the present invention is shown;

[0030] Figure 8 A schematic structural diagram of a visual system according to Embodiment 2-3 of the present invention is shown;

[0031] Figure 9 shows an MTF curve diagram of a visual system according to a second embodiment of the present invention;

[0032] Figure 10 A schematic structural diagram of a visual system according to embodiment 3-1 of the present invention is shown;

[0033] Figure 11 A schematic structural diagram of a visual system according to embodiment 3-2 of the present invention is shown;

[0034] Figure 12 A schematic structural diagram of a visual system according to embodiment 3-3 of the present invention is shown;

[0035] Figure 13 shows an MTF curve diagram of a visual system according to a third embodiment of the present invention;

[0036] Figure 14 A schematic diagram of stray light energy when the visual system of Solution 1 of the present application satisfies fz / (D1s+D1m)=2.44 and TD / (EP13+CP3)=3.04 is shown;

[0037] Figure 15 A schematic diagram of stray light energy when the visual system of Comparative Example 1 satisfies fz / (D1s+D1m)=1.30 and TD / (EP13+CP3)=2.10 is shown;

[0038] Figure 16 A schematic diagram of stray light energy is shown when the visual system of Comparative Example 2 satisfies fz / (D1s+D1m)=3.00 and TD / (EP13+CP3)=3.60.

[0039] The above drawings include the following reference numerals:

[0040] P0, lens barrel; E1, first lens; E2, second lens; E3, third lens; E4, fourth lens; P1, first spacer; P3, third spacer; LP, polarizer; RP, reflective polarizer; QWP, quarter-wave plate; BS, reflective element; IMG, imaging surface. DETAILED DESCRIPTION

[0041] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0043] In the present invention, unless otherwise specified, the directional words used, such as "up, down, top, bottom", usually refer to the directions shown in the drawings, or to the components themselves in the vertical, perpendicular or gravity direction; similarly, for ease of understanding and description, "inside and outside" refer to the inside and outside relative to the outline of each component itself, but the above directional words are not used to limit the present invention.

[0044] In the drawings, the thickness, size, and shape of the lenses are slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical and aspherical surfaces shown in the drawings are provided by way of example. That is, the shapes of the spherical and aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0045] In this document, the paraxial region refers to the area near the optical axis. If the lens surface is convex and the location of the convex surface is undefined, it means that the lens surface is convex at least in the paraxial region. If the lens surface is concave and the location of the concave surface is undefined, it means that the lens surface is concave at least in the paraxial region. The surface shape in the paraxial region can be determined according to the judgment method commonly used by those skilled in the art, using the positive or negative R value (R refers to the radius of curvature of the paraxial region, typically the R value in the lens database in optical software) to determine whether it is convex or concave. For the first side, when the R value is positive, it is determined to be convex, and when the R value is negative, it is determined to be concave. For the second side, when the R value is positive, it is determined to be concave, and when the R value is negative, it is determined to be convex. When the R value is infinite, it is determined to be flat. In this application, the first side can be the human eye side, and the second side can be the display side, where the display has an image surface IMG.

[0046] In order to solve the problem in the prior art of a four-piece visual system that reasonably arranges cemented lenses and folding elements to meet the demand for lightness and thinness, thereby causing improper lens aperture design and severe stray light, the present invention provides a visual system.

[0047] like Figures 1 to 14As shown, in an optional embodiment of the present application, the visual system includes a lens barrel and a lens group and a spacing element group arranged in the lens barrel, the lens group consists of four lenses, a polarizer, a reflective polarizing element, a quarter-wave plate and a reflective element, and the four lenses are, from the first side to the second side, a first lens with positive optical focal length, a second lens with negative optical focal length, a third lens with positive optical focal length or negative optical focal length and a fourth lens with positive optical focal length, the first side surface of the first lens is concave, and the second side surface is convex; the first side surface of the second lens is concave, and the second side surface is convex; the first side surface of the third lens is concave, and the second side surface is convex; the first side surface of the fourth lens is concave, and the second side surface is convex; the second lens and the third lens are cemented to form a cemented lens; the polarizer, the reflective polarizing element and the quarter-wave plate are arranged between the first lens and the second lens and are arranged in sequence in a direction away from the first lens; the reflective element is arranged between the third lens and the fourth lens.

[0048] The spacer element group includes a first spacer element located between the first lens and the second lens and supported by the second side surface of the first lens, and a third spacer element located between the third lens and the fourth lens and supported by the second side surface of the third lens; the combined focal length fz of the first lens, the polarizer, the reflective polarizing element and the quarter-wave plate, the outer diameter D1s of the first side surface of the first spacer element and the outer diameter D1m of the second side surface of the first spacer element satisfy: 1.72≤fz / (D1s+D1m)≤2.54; the axial distance TD from the first side surface of the first lens to the second side surface of the fourth lens, the axial spacing EP13 from the second side surface of the first spacer element to the first side surface of the third spacer element and the maximum axial thickness CP3 of the third spacer element satisfy: 2.71≤TD / (EP13+CP3)≤3.17.

[0049] The visual system of the present application is composed of a lens barrel and four lenses arranged in the lens barrel, multiple spacer elements, a polarizer, a reflective polarizer, a quarter-wave plate, and a reflective element. By reasonably setting the optical power and surface shape of each lens, the positions of the first spacer element, the third spacer element, the polarizer, the reflective polarizer, the quarter-wave plate, and the reflective element, and arranging the second lens and the third lens to form a cemented lens, it is beneficial to compress the distance between the second lens and the third lens. At the same time, the light path is planned to be refracted and reflected between the first lens and the second lens, and between the third lens and the fourth lens, which is beneficial to folding the light path, achieving compression of the total optical length, and facilitating the realization of lightweight and thinness. However, in this case, due to the influence of the lens size, the light in the visual system is reflected and scattered multiple times, forming new stray light. Therefore, this application further increases the aperture of each lens while ensuring optical performance by constraining 1.72≤fz / (D1s+D1m)≤2.54 and 2.71≤TD / (EP13+CP3)≤3.17, thereby reducing the theoretical vignetting phenomenon and improving the uniformity of light intensity within the visual range; at the same time, it ensures the rationality of the lens aperture design and reduces the risk of stray light ghost images caused by improper lens aperture design.

[0050] In addition, refer to Table 1 below. Figures 14 to 16 As shown, Figure 14 A schematic diagram of stray light energy is shown when the visual system of Solution 1 of the present application satisfies fz / (D1s+D1m)=2.44 and TD / (EP13+CP3)=3.04. Figure 15 A schematic diagram of stray light energy is shown when the visual system of Comparative Example 1 satisfies fz / (D1s+D1m)=1.30 and TD / (EP13+CP3)=2.10. Figure 16 A schematic diagram of stray light energy is shown when the visual system of Comparative Example 2 satisfies fz / (D1s+D1m)=3.00 and TD / (EP13+CP3)=3.60.

[0051] Depend on Figures 14 to 16It can be seen that when the visual system meets fz / (D1s+D1m)=2.44 and TD / (EP13+CP3)=3.04, there is less stray light, lower stray light energy, and better performance. When the visual system meets fz / (D1s+D1m)=1.30 and TD / (EP13+CP3)=2.10, there is more stray light, higher stray light energy, and poorer performance. When the visual system meets fz / (D1s+D1m)=3.00 and TD / (EP13+CP3)=3.60, there is more stray light, higher stray light energy, and poorer performance. It can be seen that when 1.72≤fz / (D1s+D1m)≤2.54 and 2.71≤TD / (EP13+CP3)≤3.17 are met, the stray light is the least and the stray light energy is the lowest. Therefore, this application further increases the aperture of each lens while ensuring optical performance by constraining 1.72≤fz / (D1s+D1m)≤2.54 and 2.71≤TD / (EP13+CP3)≤3.17, thereby reducing the theoretical vignetting phenomenon and improving the uniformity of light intensity within the visual range; at the same time, it ensures the rationality of the lens aperture design and reduces the risk of stray light ghost images caused by improper lens aperture design.

[0052] Table 1

[0053]

[0054] It should be noted that a reflective element may be provided between the third lens and the fourth lens. In a specific embodiment of the present application, the reflective element is provided on the first side surface of the fourth lens.

[0055] In this embodiment, the on-axis spacing EP01 between the first side surface of the lens barrel and the first side surface of the first spacing element, the radius of curvature R1 of the first side surface of the first lens, and the radius of curvature R2 of the second side surface of the first lens satisfy the following relationship: 6.03mm≤EP01×(R1 / R2)≤8.88mm. Properly controlling the range of this conditional expression can, on the one hand, improve the structural stability of the visual system and reduce performance fluctuations caused by temperature or stress; on the other hand, it can reduce the difficulty of assembling the first lens and the lens barrel, shorten calibration time, and improve production efficiency. It can also ensure the compatibility of the first lens and the lens barrel and ensure assembly stability.

[0056] In this embodiment, the effective focal length f1 of the first lens element and the outer diameter D0s of the first side surface of the lens barrel satisfy the following condition: 3.12 ≤ f1 / D0s ≤ 4.61. Properly controlling the range of this conditional expression can enhance the resolution of the visual system and produce a more detailed image. This ensures that the first lens can receive wide-angle light from the first side without obstructing the light from the lens barrel, thereby improving image quality in peripheral areas and reducing blur or distortion.

[0057] In this embodiment, the inner diameter d1m of the second side surface of the first spacer element 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 the following condition: 11.23 ≤ d1m / T12 ≤ 15.17. Properly controlling the range of this conditional expression helps to properly control the effective aperture of the first lens within a reasonable range, ensuring efficient light transmission between the first and second lenses, reducing light energy loss, and improving luminous flux. It also reduces deformation of the lenses or spacer element caused by heat accumulation, ensuring stable performance.

[0058] In this embodiment, the inner diameter d3s of the first side surface of the third spacer element and the radius of curvature R6 of the second side surface of the third lens satisfy the following condition: -1.34 ≤ d3s / R6 ≤ -1.19. Properly controlling the range of this conditional expression can improve the compatibility of the third spacer element and the third lens, simplify assembly of the third lens and the third spacer element, and enhance production efficiency and consistency. It can also reduce the surface sensitivity of the third lens and improve processing yield.

[0059] In this embodiment, the combined focal length f23 of the second and third lenses, the outer diameter D3s of the first side of the third spacer element, and the outer diameter D3m of the second side of the third spacer element satisfy the following equation: -4.84 ≤ f23 / (D3s + D3m) ≤ -4.45. By properly controlling this conditional range and adjusting the light path through a lens combination with a negative focal length, the field of view can be expanded while minimizing edge distortion, meeting the wide viewing angle requirements of visual systems. This also ensures the structural strength of the third spacer element, preventing either structural fragility due to undersizing or increased weight due to oversizing.

[0060] In this embodiment, the inner diameter d0m of the second side surface of the lens barrel and the radius of curvature R8 of the second side surface of the fourth lens element satisfy the following relationship: -2.79 ≤ d0m / R8 ≤ -1.78. Properly controlling this conditional expression ensures that light rays passing through the fourth lens element are more accurately focused on the retina, thereby reducing blur and ghosting, improving image clarity, and enhancing wearing comfort by reducing eye strain or discomfort.

[0061] In this embodiment, the effective focal length f4 of the fourth lens element and the inner diameter d3m of the second side surface of the third spacer element satisfy the following condition: 1.81 ≤ f4 / d3m ≤ 8.26. Properly controlling this conditional range can reduce light energy loss, achieve more uniform illumination across the image plane, and particularly improve brightness consistency around edge areas. Furthermore, the third spacer element blocks non-imaging light without blocking imaging light, reducing the impact of stray light on the image, minimizing ghosting and glare, and improving contrast.

[0062] In this embodiment, the inner diameter d0s of the first side of the lens barrel and the entrance pupil diameter (EPD) of the visual system satisfy the following relationship: 9.67 ≤ d0s / EPD ≤ 10.91. Properly controlling the range of this conditional expression facilitates the visual system's support of a wider field of view or a larger incident light beam, allowing for more stable passage of marginal light and reducing obstruction of incident light by the lens barrel, thereby improving imaging quality. It also allows the use of low thermal expansion coefficient materials, provides sufficient deformation margin, or allows for compatibility with active heat dissipation designs, thereby reducing fluctuations in optical performance caused by temperature changes.

[0063] In this embodiment, the on-axis spacing EP13 between the second side surface of the first spacer element and the first side surface of the third spacer element, the effective focal length f2 of the second lens, and the effective focal length f3 of the third lens satisfy the following: 2.35mm ≤ EP13 × |f2 / f3| ≤ 12.56mm. Properly controlling the range of this conditional expression facilitates a more realistic virtual reality experience for the visual system, allowing the wearer to experience a more natural, three-dimensional visual effect. It also ensures that light converges or diverges within the visual system without abrupt changes, minimizing field curvature and facilitating a greater depth of focus.

[0064] In this embodiment, the axial spacing EP01 between the first side surface of the lens barrel and the first side surface of the first spacer element, the maximum axial thickness CP1 of the first spacer element, and the center thickness CT1 of the first lens on the optical axis of the visual system satisfy the following equation: 1.22 ≤ (EP01 + CP1) / CT1 ≤ 1.64. Properly controlling the range of this conditional expression reduces sensitivity to the center and edge thicknesses of the first lens, as well as the structural thickness of the first side end of the lens barrel, thereby improving assembly stability between the first lens and the lens barrel and boosting overall yield. Furthermore, the mechanical strength requirements for the first spacer element are lower, contributing to cost reduction.

[0065] In this embodiment, the outer diameter D0m of the second side surface of the lens barrel and the effective focal length f of the visual system satisfy the following relationship: 2.02 ≤ D0m / f ≤ 2.45. Properly controlling the range of this conditional expression allows each lens in the visual system to have a more gradual curvature, which helps reduce aberrations and facilitates smoother refraction of light passing through the lens, thus reducing aberrations. This also balances the field of view and magnification, ensuring that the image viewed by the user has a sufficiently large field of view without compromising image quality or requiring a higher screen resolution due to excessive magnification.

[0066] In this embodiment, the inner diameter d1s of the first side surface of the first spacer element and the on-axis spacing L between the first side surface and the second side surface of the lens barrel satisfy the following condition: 1.72 ≤ d1s / L ≤ 2.16. Properly controlling this conditional expression ensures that the ratio of the lens barrel's dimensions along the optical axis to the field of view dimensions is within a reasonable range, minimizing the weight and thickness differences along the optical axis and radial directions, thus ergonomically accommodating the visual system. This also reduces the difficulty of visual system assembly and significantly improves process yield.

[0067] In this embodiment, the inner diameter d3s of the first side surface of the third spacer element, the inner diameter d1s of the first side surface of the first spacer element, the center thickness CT2 of the second lens on the optical axis of the visual system, and the center thickness CT3 of the third lens on the optical axis satisfy the following relationship: 2.12 ≤ (d3s - d1s) / (CT2 + CT3) ≤ 2.96. Properly controlling the range of this conditional expression ensures that the apertures of the first through third lenses gradually increase in sequence, while minimizing the overall length of the system and minimizing the weight bearing on the nasal bridge. This improves wearability, reduces sensitivity to eye position, and enhances the user experience.

[0068] In addition, in another optional embodiment of the present application, a visual system is also provided, including a lens barrel and a lens group and a spacer element group arranged in the lens barrel, the lens group consisting of four lenses, a polarizer, a reflective polarizing element, a quarter-wave plate and a reflective element, the four lenses are, from the first side to the second side, a first lens with positive optical focal power, a second lens with negative optical focal power, a third lens with positive optical focal power or negative optical focal power and a fourth lens with positive optical focal power, the first side surface of the first lens is concave, and the second side surface is convex; the first side surface of the second lens is concave, and the second side surface is convex; the first side surface of the third lens is concave, and the second side surface is convex; the first side surface of the fourth lens is concave, and the second side surface is convex; the second lens and the third lens are cemented to form a cemented lens; the polarizer, the reflective polarizing element and the quarter-wave plate are arranged between the first lens and the second lens and are arranged in sequence in a direction away from the first lens; the reflective element is arranged between the third lens and the fourth lens.

[0069] The spacer element group includes a first spacer element located between the first lens and the second lens and supported by the second side surface of the first lens, and a third spacer element located between the third lens and the fourth lens and supported by the second side surface of the third lens; the combined focal length fz of the first lens, the polarizer, the reflective polarizing element and the quarter-wave plate, the outer diameter D1s of the first side surface of the first spacer element and the outer diameter D1m of the second side surface of the first spacer element satisfy the following: 1.72≤fz / (D1s+D1m)≤2.54; the effective focal length f4 of the fourth lens and the inner diameter d3m of the second side surface of the third spacer element satisfy the following: 1.81≤f4 / d3m≤8.26.

[0070] The visual system of the present application comprises a lens barrel and four lenses disposed therein, a plurality of spacer elements, a polarizer, a reflective polarizer, a quarter-wave plate, and a reflective element. By rationally setting the optical power and surface shape of each lens, the positions of the first spacer element, the third spacer element, the polarizer, the reflective polarizer, the quarter-wave plate, and the reflective element, and arranging the second lens and the third lens to form a cemented lens, the distance between the second lens and the third lens is compressed. At the same time, the light path is refracted and reflected between the first lens and the second lens, and between the third lens and the fourth lens, which is conducive to folding the light path, compressing the total optical length, and achieving lightweight and thinness. However, in this case, due to the influence of the lens size, the light in the visual system is reflected and scattered multiple times, forming new stray light. Therefore, this application further increases the aperture of each lens while ensuring optical performance by constraining 1.72≤fz / (D1s+D1m)≤2.54 and 1.81≤f4 / d3m≤8.26, thereby reducing the theoretical vignetting phenomenon and improving the uniformity of light intensity within the visual range; at the same time, it ensures the rationality of the lens aperture design and reduces the risk of stray light and ghost images caused by improper lens aperture design; at the same time, it can reduce light energy loss, make the illumination of the image surface more uniform, and especially improve the brightness consistency of the edge area; at the same time, it ensures that non-imaging light is blocked without blocking the imaging light, reduces the impact of stray light on imaging, reduces ghosting and glare, and improves contrast.

[0071] Of course, this embodiment may also include other parameter formulas in the above embodiment, which will not be described one by one here.

[0072] Optionally, the visual system in the embodiments of the present application can be simulated using software and / or tools such as ZEMAX and CODEV. During the simulation using the above-mentioned software and / or tools, the surface profile of each lens can be appropriately adjusted based on the surface profile provided by the software and / or tool used.

[0073] Optionally, the visual system may further include a protective glass for protecting the photosensitive element located on the image surface.

[0074] The visual system in this application can utilize multiple lenses, such as the four lenses described above. In this application, at least one of the lens surfaces is an aspheric surface. Aspheric lenses are characterized by a continuously changing curvature from the center to the periphery of the lens. Unlike spherical lenses, which have a constant curvature from the center to the periphery, aspheric lenses have a better curvature radius characteristic, with the advantages of improving distortion and astigmatism. The use of aspheric lenses can minimize aberrations that occur during imaging, thereby improving image quality.

[0075] However, those skilled in the art will appreciate that the number of lenses comprising the visual system can be varied to achieve the various results and advantages described herein without departing from the technical solutions claimed herein. For example, while four lenses are described as an example in the embodiments, the visual system is not limited to four lenses. If desired, the visual system can also include other numbers of lenses.

[0076] Figure 1 A schematic diagram of dimension marking of a visual system of the present application is shown. Figure 1 Parameters such as D0s, D3s, D1s, d3s, d1s, d0s, d1m, d3m, D1m, D3m, d0m, D0m, EP01, EP13, L, CP1, and CP3 are labeled to provide a clear and intuitive understanding of their significance. To facilitate the description of the visual system and specific lens surface shapes, these parameters will not be reflected in the accompanying drawings when describing specific embodiments.

[0077] The following further describes examples of specific surface shapes and parameters of the visual system applicable to the above-mentioned embodiment with reference to the accompanying drawings.

[0078] It should be noted that in the following Example 1, there are three examples: Example 1-1, Example 1-2, and Example 1-3; in Example 2, there are three examples: Example 2-1, Example 2-2, and Example 2-3; and in Example 3, there are three examples: Example 3-1, Example 3-2, and Example 3-3. The optical system parameters of the three examples in the same embodiment are the same. Specifically, the parameters such as the curvature radius and center thickness of the first to fourth lenses of the visual system, as well as the spacing between the lenses and the higher-order coefficients are the same. However, the parameters such as the thickness, inner diameter, and outer diameter of the lens barrel, the first spacer element, and the third spacer element are different.

[0079] It should be noted that any one of the following examples 1 to 3 is applicable to all implementation methods of the present application.

[0080] Example 1

[0081] like Figures 2 to 5 As shown, the visual system of embodiment 1 is described. Figure 2 1-1 shows a schematic structural diagram of the visual system of Example 1-1. Figure 3 shows a schematic structural diagram of the visual system of Example 1-2, Figure 4 Schematic diagrams of the structures of the visual systems of Examples 1-3 are shown.

[0082] like Figures 2 to 4As shown, the visual system includes a lens barrel P0 and, arranged in sequence from the first side to the second side of the optical axis within lens barrel P0, a first lens E1, a first spacer element P1, a second lens E2, a third lens E3, a third spacer element P3, and a fourth lens E4. A polarizer LP, a reflective polarizer RP, and a quarter-wave plate QWP are also arranged in sequence from the first side to the second side between the first lens E1 and the second lens E2. A reflective element BS is also positioned between the third lens E3 and the fourth lens E4. The second lens E2 and the third lens E3 are cemented together to form a cemented lens.

[0083] In this embodiment, the polarizer LP, the reflective polarizer RP, and the quarter-wave plate QWP are sequentially arranged on the second side surface of the first lens E1 in a direction away from the first lens E1 , and the reflective element BS is arranged on the first side surface of the fourth lens.

[0084] In this embodiment, light emitted from the image surface IMG is sequentially transmitted through the fourth lens E4, the third lens E3, the second lens E2, and the quarter-wave plate QWP before entering the reflective polarizer RP. After being reflected by the reflective polarizer RP, the light is transmitted toward the display. The light is then sequentially transmitted through the quarter-wave plate QWP, the second lens E2, and the third lens E3 before entering the reflective element BS. After being reflected by the reflective element BS, the light is transmitted toward the human eye. The light is then sequentially transmitted through the third lens E3, the second lens E2, the quarter-wave plate QWP, the reflective polarizer RP, the polarizer LP, and the first lens E1 before entering the human eye to form an image.

[0085] like Figure 2 Figure 2 is a schematic diagram of the structure of the visual system of Example 1-1. In this example, the first and second side surfaces of the first spacer element P1 respectively abut the second side surface of the first lens and the first side surface of the second lens. The first and second side surfaces of the third spacer element P3 respectively abut the second side surface of the third lens and the first side surface of the fourth lens.

[0086] like Figure 3 FIG. 1 is a schematic diagram of the structure of the visual system of Example 1-2. In this example, the supporting and abutting manner of each spacer element is the same as that of Example 1-1, and reference may be made to the relevant description in Example 1-1, which will not be repeated here.

[0087] like Figure 4 FIG. 3 is a schematic diagram of the structure of the visual system of Example 1-3. In this example, the supporting and abutting manner of each spacer element is the same as that of Example 1-1, and reference may be made to the relevant description in Example 1-1, which will not be repeated here.

[0088] In summary, the structural parameters of the visual system of Example 1 in Example 1-1, Example 1-2, and Example 1-3 are shown in Table 2 (unit: mm).

[0089] Table 2

[0090]

[0091] In Example 1, the first side surface of the first lens is concave, and the second side surface of the first lens is convex. The first side surface of the second lens is concave, and the second side surface of the second lens is convex. The first side surface of the third lens is concave, and the second side surface of the third lens is convex. The first side surface of the fourth lens is concave, and the second side surface of the fourth lens is convex.

[0092] In Example 1, the effective focal length f of the visual system is 28.26 mm, the effective focal length f1 of the first lens is 193.71 mm, the effective focal length f2 of the second lens is -2364.65 mm, the effective focal length f3 of the third lens is -712.47 mm, the effective focal length f4 of the fourth lens is 190.43 mm, the combined focal length f23 of the second lens and the third lens is -539.89 mm, the combined focal length fz of the first lens, the polarizer, the reflective polarizing element and the quarter-wave plate is 193.12 mm, the axial distance TD from the first side surface of the first lens to the second side surface of the fourth lens is 16.70 mm, and the entrance pupil diameter EPD of the visual system is 4.00 mm.

[0093] Table 3 shows the basic structural parameters of the visual system of Example 1, wherein the units of curvature radius and thickness / distance are all millimeters.

[0094] Table 3

[0095]

[0096] In Example 1, the first side surfaces and the second side surfaces of the first lens E1 to the fourth lens E4 are all aspherical surfaces. The surface shape of each aspherical lens can be defined by, but not limited to, the following aspherical surface formula:

[0097] Formula (1).

[0098] Where x is the distance vector from the vertex of the aspheric surface 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 radius of curvature R in Table 3 above; k is the conic coefficient; Ai is the correction coefficient for the i-th order of the aspheric surface. Table 4 below lists the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for each of the aspheric surfaces 2-24 in Example 1.

[0099] Table 4

[0100]

[0101] Figure 5 The MTF curve of the visual system of Example 1 is shown. As can be seen from the figure, the higher the MTF curve is, the better the imaging quality is at this spatial frequency.

[0102] Example 2

[0103] like Figures 6 to 9 As shown, the visual system of embodiment 2 is described. Figure 6 Schematic diagram of the structure of the visual system of Example 2-1 is shown. Figure 7 2-2 shows a schematic structural diagram of the visual system of Example 2-2. Figure 8 A schematic structural diagram of the visual system of Example 2-3 is shown.

[0104] like Figures 6 to 8 As shown, the visual system includes a lens barrel P0 and, arranged in sequence from the first side to the second side of the optical axis within lens barrel P0, a first lens E1, a first spacer element P1, a second lens E2, a third lens E3, a third spacer element P3, and a fourth lens E4. A polarizer LP, a reflective polarizer RP, and a quarter-wave plate QWP are also arranged in sequence from the first side to the second side between the first lens E1 and the second lens E2. A reflective element BS is also positioned between the third lens E3 and the fourth lens E4. The second lens E2 and the third lens E3 are cemented together to form a cemented lens.

[0105] In this embodiment, the polarizer LP, the reflective polarizer RP, and the quarter-wave plate QWP are sequentially arranged on the second side surface of the first lens E1 in a direction away from the first lens E1 , and the reflective element BS is arranged on the first side surface of the fourth lens.

[0106] In this embodiment, light emitted from the image surface IMG is sequentially transmitted through the fourth lens E4, the third lens E3, the second lens E2, and the quarter-wave plate QWP before entering the reflective polarizer RP. After being reflected by the reflective polarizer RP, the light is transmitted toward the display. The light is then sequentially transmitted through the quarter-wave plate QWP, the second lens E2, and the third lens E3 before entering the reflective element BS. After being reflected by the reflective element BS, the light is transmitted toward the human eye. The light is then sequentially transmitted through the third lens E3, the second lens E2, the quarter-wave plate QWP, the reflective polarizer RP, the polarizer LP, and the first lens E1 before entering the human eye to form an image.

[0107] like Figure 6Figure 2 shows a schematic diagram of the visual system structure of Example 2-1. In this example, the first and second side surfaces of the first spacer element P1 respectively abut the second side surface of the first lens and the first side surface of the second lens. The first and second side surfaces of the third spacer element P3 respectively abut the second side surface of the third lens and the first side surface of the fourth lens.

[0108] like Figure 7 FIG2 is a schematic diagram of the structure of the visual system of Example 2-2. In this example, the supporting and abutting manner of each spacer element is the same as that of Example 2-1. Please refer to the relevant description in Example 2-1 and will not be repeated here.

[0109] like Figure 8 FIG2 is a schematic diagram of the structure of the visual system of Example 2-3. In this example, the supporting and abutting manner of each spacer element is the same as that of Example 2-1. Please refer to the relevant description of Example 2-1 and will not be repeated here.

[0110] In summary, the structural parameters of the visual system of Example 2 in Example 2-1, Example 2-2, and Example 2-3 are shown in Table 5 (unit: mm).

[0111] Table 5

[0112]

[0113] In Example 2, the first side surface of the first lens is concave, and the second side surface of the first lens is convex. The first side surface of the second lens is concave, and the second side surface of the second lens is convex. The first side surface of the third lens is concave, and the second side surface of the third lens is convex. The first side surface of the fourth lens is concave, and the second side surface of the fourth lens is convex.

[0114] In Example 2, the effective focal length f of the visual system is 29.59 mm, the effective focal length f1 of the first lens is 187.43 mm, the effective focal length f2 of the second lens is -677.74 mm, the effective focal length f3 of the third lens is -1634.18 mm, the effective focal length f4 of the fourth lens is 408.25 mm, the combined focal length f23 of the second lens and the third lens is -481.87 mm, the combined focal length fz of the first lens, the polarizer, the reflective polarizing element, and the quarter-wave plate is 186.84 mm, the on-axis distance TD from the first side surface of the first lens to the second side surface of the fourth lens is 16.86 mm, and the entrance pupil diameter EPD of the visual system is 4.00 mm.

[0115] Table 6 shows the basic structural parameters of the visual system of Example 2, wherein the units of curvature radius and thickness / distance are all millimeters.

[0116] Table 6

[0117]

[0118] Table 7 below lists the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for each aspheric surface in Example 2.

[0119] Table 7

[0120]

[0121] Figure 9 The MTF curve of the visual system of Example 2 is shown. As can be seen from the figure, a higher MTF curve indicates better imaging quality at this spatial frequency.

[0122] Example 3

[0123] like Figures 10 to 13 As shown, the visual system of embodiment 3 is described. Figure 10 The schematic diagram of the structure of the visual system of Example 3-1 is shown. Figure 11 Schematic diagram of the structure of the visual system of Example 3-2 is shown. Figure 12 A schematic structural diagram of the visual system of Example 3-3 is shown.

[0124] like Figures 10 to 12 As shown, the visual system includes a lens barrel P0 and, arranged in sequence from the first side to the second side of the optical axis within lens barrel P0, a first lens E1, a first spacer element P1, a second lens E2, a third lens E3, a third spacer element P3, and a fourth lens E4. A polarizer LP, a reflective polarizer RP, and a quarter-wave plate QWP are also arranged in sequence from the first side to the second side between the first lens E1 and the second lens E2. A reflective element BS is also positioned between the third lens E3 and the fourth lens E4. The second lens E2 and the third lens E3 are cemented together to form a cemented lens.

[0125] In this embodiment, the polarizer LP, the reflective polarizer RP, and the quarter-wave plate QWP are sequentially arranged on the second side surface of the first lens E1 in a direction away from the first lens E1 , and the reflective element BS is arranged on the first side surface of the fourth lens.

[0126] In this embodiment, light emitted from the image surface IMG is sequentially transmitted through the fourth lens E4, the third lens E3, the second lens E2, and the quarter-wave plate QWP before entering the reflective polarizer RP. After being reflected by the reflective polarizer RP, the light is transmitted toward the display. The light is then sequentially transmitted through the quarter-wave plate QWP, the second lens E2, and the third lens E3 before entering the reflective element BS. After being reflected by the reflective element BS, the light is transmitted toward the human eye. The light is then sequentially transmitted through the third lens E3, the second lens E2, the quarter-wave plate QWP, the reflective polarizer RP, the polarizer LP, and the first lens E1 before entering the human eye to form an image.

[0127] like Figure 10 Figure 3-1 shows a schematic diagram of the visual system structure of Example 3-1. In this example, the first and second side surfaces of the first spacer element P1 respectively abut the second side surface of the first lens and the first side surface of the second lens. The first and second side surfaces of the third spacer element P3 respectively abut the second side surface of the third lens and the first side surface of the fourth lens.

[0128] like Figure 11 FIG3 is a schematic diagram of the structure of the visual system of Example 3-2. In this example, the supporting and abutting manner of each spacer element is the same as that of Example 3-1. Please refer to the relevant description in Example 3-1 and will not be repeated here.

[0129] like Figure 12 FIG3 is a schematic diagram of the structure of the visual system of Example 3-3. In this example, the supporting and abutting manner of each spacer element is the same as that of Example 3-1. Please refer to the relevant description of Example 3-1 and will not be repeated here.

[0130] In summary, the structural parameters of the visual system of Example 3 in Example 3-1, Example 3-2, and Example 3-3 are shown in Table 8 (unit: mm).

[0131] Table 8

[0132]

[0133] In Example 3, the first side surface of the first lens is concave, and the second side surface of the first lens is convex. The first side surface of the second lens is concave, and the second side surface of the second lens is convex. The first side surface of the third lens is concave, and the second side surface of the third lens is convex. The first side surface of the fourth lens is concave, and the second side surface of the fourth lens is convex.

[0134] In Example 3, the effective focal length f of the visual system is 28.17 mm, the effective focal length f1 of the first lens is 257.04 mm, the effective focal length f2 of the second lens is -230.14 mm, the effective focal length f3 of the third lens is 442.03 mm, the effective focal length f4 of the fourth lens is 90.73 mm, the combined focal length f23 of the second lens and the third lens is -510.58 mm, the combined focal length fz of the first lens, the polarizer, the reflective polarizing element and the quarter-wave plate is 255.95 mm, the axial distance TD from the first side surface of the first lens to the second side surface of the fourth lens is 17.20 mm, and the entrance pupil diameter EPD of the visual system is 4.00 mm.

[0135] Table 9 shows the basic structural parameters of the visual system of Example 3, where the units of curvature radius and thickness / distance are all millimeters.

[0136] Table 9

[0137]

[0138] Table 10 below lists the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 that can be used for each aspherical surface in Example 3.

[0139] Table 10

[0140]

[0141] Figure 13 The MTF curve of the visual system of Example 3 is shown. As can be seen from the figure, the higher the MTF curve is, the better the imaging quality is at this spatial frequency.

[0142] In summary, Examples 1 to 3 respectively satisfy the relationships shown in Table 11.

[0143] Table 11

[0144]

[0145] Table 12 shows the effective focal length of the visual system and the effective focal length of each lens in Examples 1 to 3.

[0146] Table 12

[0147]

[0148] This application also provides an imaging device, whose electronic photosensitive element can be a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). The imaging device can be a standalone imaging device such as a digital camera, or an imaging module integrated into a mobile electronic device such as a mobile phone. The imaging device is equipped with the visual system described above.

[0149] Optionally, the imaging device may be a VR device or an AR device.

[0150] Obviously, the embodiments described above are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0151] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, tasks, devices, components and / or combinations thereof.

[0152] It should be noted that the terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0153] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A visual system, characterized in that: comprising a lens barrel and a lens group and a spacer element group arranged in the lens barrel, The lens assembly is composed of four lenses, a polarizer, a reflective polarizing element, a quarter-wave plate, and a reflective element. The four lenses are, from the first side to the second side, a first lens with positive optical power, a second lens with negative optical power, a third lens with positive optical power or negative optical power, and a fourth lens with positive optical power. The first side surface of the first lens is concave, and the second side surface is convex; the first side surface of the second lens is concave, and the second side surface is convex; the first side surface of the third lens is concave, and the second side surface is convex; the first side surface of the fourth lens is concave, and the second side surface is convex; the second lens is cemented with the third lens to form a cemented lens; The polarizer, the reflective polarizing element, and the quarter-wave plate are disposed between the first lens and the second lens and are arranged in sequence in a direction away from the first lens; the reflective element is disposed between the third lens and the fourth lens; The spacer element group includes a first spacer element located between the first lens and the second lens and abutting against the second side surface of the first lens, and a third spacer element located between the third lens and the fourth lens and abutting against the second side surface of the third lens; The combined focal length fz of the first lens, the polarizer, the reflective polarizer, and the quarter-wave plate, the outer diameter D1s of the first side surface of the first spacer element, and the outer diameter D1m of the second side surface of the first spacer element satisfy the following relationship: 1.72≤fz / (D1s+D1m)≤2.54; The on-axis distance TD from the first side surface of the first lens to the second side surface of the fourth lens, the on-axis spacing EP13 from the second side surface of the first spacer element to the first side surface of the third spacer element, and the maximum axial thickness CP3 of the third spacer element satisfy the following: 2.71≤TD / (EP13+CP3)≤3.

17.

2. The visual system according to claim 1, characterized in that: The axial spacing EP01 from the first side surface of the lens barrel to the first side surface of the first spacing element, the curvature radius R1 of the first side surface of the first lens, and the curvature radius R2 of the second side surface of the first lens satisfy: 6.03mm≤EP01×(R1 / R2)≤8.88mm.

3. The visual system according to claim 1, wherein: The effective focal length f1 of the first lens and the outer diameter D0s of the first side surface of the lens barrel satisfy the following: 3.12≤f1 / D0s≤4.

61.

4. The visual system according to claim 1, wherein: An inner diameter d1m of the second side surface of the first spacer element and an axial distance T12 from the second side surface of the first lens to the first side surface of the second lens satisfy the following: 11.23≤d1m / T12≤15.

17.

5. The visual system according to claim 1, wherein: An inner diameter d3s of the first side surface of the third spacer element and a curvature radius R6 of the second side surface of the third lens satisfy the following relationship: -1.34≤d3s / R6≤-1.

19.

6. The visual system according to claim 1, wherein: The combined focal length f23 of the second lens and the third lens, the outer diameter D3s of the first side surface of the third spacing element, and the outer diameter D3m of the second side surface of the third spacing element satisfy the following: -4.84≤f23 / (D3s+D3m)≤-4.

45.

7. The visual system according to claim 1, wherein: An inner diameter d0m of the second side surface of the lens barrel and a curvature radius R8 of the second side surface of the fourth lens satisfy the following relationship: -2.79≤d0m / R8≤-1.

78.

8. The visual system according to claim 1, wherein: The effective focal length f4 of the fourth lens and the inner diameter d3m of the second side surface of the third spacer element satisfy the following: 1.81≤f4 / d3m≤8.

26.

9. The visual system according to claim 1, wherein: The inner diameter d0s of the first side surface of the lens barrel and the entrance pupil diameter EPD of the visual system satisfy the following: 9.67≤d0s / EPD≤10.

91.

10. The visual system according to claim 1, wherein: The on-axis spacing EP13 from the second side surface of the first spacing element to the first side surface of the third spacing element, the effective focal length f2 of the second lens, and the effective focal length f3 of the third lens satisfy the following: 2.35mm≤EP13×|f2 / f3|≤12.56mm.

11. The visual system according to claim 1, wherein: The axial distance EP01 from the first side surface of the lens barrel to the first side surface of the first spacer element, the maximum axial thickness CP1 of the first spacer element and the center thickness CT1 of the first lens on the optical axis of the visual system satisfy: 1.22≤(EP01+CP1) / CT1≤1.

64.

12. The visual system according to claim 1, wherein: The outer diameter D0m of the second side surface of the lens barrel and the effective focal length f of the visual system satisfy the following: 2.02≤D0m / f≤2.

45.

13. The visual system according to any one of claims 1 to 12, characterized in that: The inner diameter d1s of the first side surface of the first spacing element and the axial distance L from the first side surface to the second side surface of the lens barrel satisfy the following: 1.72≤d1s / L≤2.

16.

14. The visual system according to any one of claims 1 to 12, characterized in that: The inner diameter d3s of the first side surface of the third spacer element, the inner diameter d1s of the first side surface of the first spacer element, the center thickness CT2 of the second lens on the optical axis of the visual system, and the center thickness CT3 of the third lens on the optical axis satisfy the following: 2.12≤(d3s-d1s) / (CT2+CT3)≤2.96.

Images