Visual system

Abstract

The invention provides a visual system. The visual system comprises a lens barrel, a lens group and a spacing element group, the lens group and the spacing element group are arranged in the lens barrel, the lens group is composed of four lenses, a polarizing film, a reflective polarizing element, a quarter-wave plate and a reflecting element, and fz / (D1s + D1m) is larger than or equal to 1.72 and smaller than or equal to 2.54; tD / (EP13 + CP3) is greater than or equal to 2.71 and less than or equal to 3.17. According to the invention, the problem of serious stray light caused by improper lens aperture design due to the fact that a four-piece visual system in the prior art meets the light and thin requirements by reasonably arranging a bonding lens and a turn-back element is solved.

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 with human-computer interaction have been sought after and loved by more and more people, and their market demand is also growing. As a key component of VR devices, the performance of the visual system directly affects the user's visual experience and the overall performance of the device. The four-piece visual system is widely used in various VR devices due to its small number of lenses and simple structure.

[0003] At present, in order to meet the development needs of thinness and lightness, the four-piece visual system is conducive to compressing the total length of the visual system by reasonably setting the cemented lens and the return element. In this case, the design of the lens aperture has certain limitations. If the lens aperture is not designed properly, the light in the visual system is easily reflected and scattered multiple times due to the size of the lens, which will form new stray light. These stray lights will form ghost images in the imaging picture, seriously affecting the image quality of the visual system.

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

[0005] The main purpose of the present invention is to provide a visual system to solve the problem that the four-piece visual system in the prior art meets the demand for lightness and thinness by reasonably arranging the glued lenses and the folding elements, thereby improperly designing the lens aperture and causing 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 spacing element group arranged in the lens barrel, wherein the lens group consists of four lenses, a polarizing plate, a reflective polarizing element, a quarter wave plate and a reflecting 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 a concave surface and the second side surface is a convex surface; the first side surface of the second lens is a concave 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 concave surface and the second side surface is a convex surface; the second lens and the third lens are glued together to form a glued lens; the polarizing plate, 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 spacing 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 a concave surface and the second side surface is a convex surface; the first side surface of the second lens is a concave 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 concave surface and the second side surface is a convex surface; the second lens and the third lens are glued together to form a glued lens; the polarizing plate, the reflective polarizing element and the quarter wave plate are arranged The first lens and the second lens are arranged in sequence along the 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 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 effective focal length f4 of the fourth lens and the inner diameter d3m of the second side surface of the third spacer element satisfy: 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: 3.12≤f1 / D0s≤4.61.

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

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

[0012] Further, 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: -4.84≤f23 / (D3s+D3m)≤-4.45.

[0013] Further, 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: -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 spacing element satisfy: 1.81≤f4 / d3m≤8.26.

[0015] Further, 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: 2.35mm≤EP13×|f2 / f3|≤12.56mm.

[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] Further, 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: 1.72≤d1s / L≤2.16.

[0020] Furthermore, the inner diameter d3s of the first side of the third spacer element, the inner diameter d1s of the first side 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: 2.12≤(d3s-d1s) / (CT2+CT3)≤2.96.

[0021] By applying the technical solution of the present invention, the visual system of the present application is composed of a lens barrel and four lenses, a plurality of spacing elements, a polarizer, a reflective polarizing element, a quarter wave plate and a reflective element arranged in the lens barrel. By reasonably setting the focal length and surface shape of each lens, the positions of the first spacing element, the third spacing element, the polarizer, the reflective polarizing element, the quarter wave plate and the reflective element, and setting the second lens and the third lens to be glued to form a glued 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, realizing the compression of the total optical length, and realizing the light-weighting. However, in this case, affected by the size of the lens, the light in the visual system is reflected and scattered multiple times, forming new stray light. Therefore, in this application, by constraining 1.72≤fz / (D1s+D1m)≤2.54 and 2.71≤TD / (EP13+CP3)≤3.17, the aperture of each lens is further increased while ensuring the optical performance, thereby reducing the theoretical vignetting phenomenon and improving the uniformity of light intensity within the visual range; at the same time, the rationality of the lens aperture design is ensured, reducing the risk of stray light ghost images caused by improper lens aperture design. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

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

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

[0025] Figure 3 A schematic diagram showing the structure of the visual system of Embodiment 1-2 of the present invention is shown;

[0026] Figure 4 A schematic diagram showing the structure of the visual system of Embodiments 1-3 of the present invention is shown;

[0027] Figure 5 The MTF curve diagram of the visual system of the first embodiment of the present invention is shown;

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

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

[0030] Figure 8 A schematic diagram showing the structure of the visual system of Embodiment 2-3 of the present invention is shown;

[0031] Fig. 9 The MTF curve diagram of the visual system of the second embodiment of the present invention is shown;

[0032] Fig.10 A schematic diagram showing the structure of a visual system according to Embodiment 3-1 of the present invention is shown;

[0033] Fig.11 A schematic diagram showing the structure of the visual system of Example 3-2 of the present invention is shown;

[0034] Fig.12 A schematic diagram showing the structure of a visual system according to Embodiment 3-3 of the present invention is shown;

[0035] Fig.13 The MTF curve diagram of the visual system of the third embodiment of the present invention is shown;

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

[0037] Fig.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] Fig.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 spacing element; P3, third spacing element; LP, polarizer; RP, reflective polarizing element; QWP, quarter wave plate; BS, reflective element; IMG, image plane. DETAILED DESCRIPTION

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present 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 meanings 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 directions; 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-mentioned directional words are not used to limit the present invention.

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

[0045] In this article, the paraxial area refers to the area 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 area; 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 area. The judgment of the surface type in the paraxial area can be based on the judgment method of the general knowledge in this field, and the positive and negative R value (R refers to the radius of curvature of the paraxial area, usually refers to the R value on the lens database (lens data) in the optical software) is used to judge the concave and convex. For the first side, when the R value is positive, it is judged as a convex surface, and when the R value is negative, it is judged as a concave surface; for the second side, when the R value is positive, it is judged as a concave surface, and when the R value is negative, it is judged as a convex surface. When the R value is infinite, it is judged as a plane. In the present application, the first side can be the human eye side, and the second side can be the display side, and the display has an image surface IMG.

[0046] In order to solve the problem that the four-piece visual system in the prior art reasonably arranges the glued lens and the folding element to meet the demand of lightness and thinness, thereby improperly designing the lens aperture and causing serious 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, 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 glued to form a glued 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, a plurality of spacing elements, a polarizer, a reflective polarizing element, a quarter wave plate and a reflective element. By reasonably setting the focal length and surface shape of each lens, the positions of the first spacing element, the third spacing element, the polarizer, the reflective polarizing element, the quarter wave plate and the reflective element, and setting the second lens and the third lens to be glued to form a glued 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, realizing the compression of the total optical length, and realizing the light-weighting. However, in this case, affected by the size of the lens, the light in the visual system is reflected and scattered multiple times, forming new stray light. Therefore, in this application, by constraining 1.72≤fz / (D1s+D1m)≤2.54 and 2.71≤TD / (EP13+CP3)≤3.17, the aperture of each lens is further increased while ensuring the optical performance, thereby reducing the theoretical vignetting phenomenon and improving the uniformity of light intensity within the visual range; at the same time, the rationality of the lens aperture design is ensured, reducing the risk of stray light ghost images caused by improper lens aperture design.

[0050] In addition, refer to the following table 1, Figures 14 to 16 As shown, Fig.14 A schematic diagram of stray light energy is shown when the visual system of Scheme 1 of the present application satisfies fz / (D1s+D1m)=2.44 and TD / (EP13+CP3)=3.04. Fig.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. Fig.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, the stray light energy is lower, and the performance is better. When the visual system meets fz / (D1s+D1m)=1.30 and TD / (EP13+CP3)=2.10, there is more stray light, the stray light energy is higher, and the performance is poor. When the visual system meets fz / (D1s+D1m)=3.00 and TD / (EP13+CP3)=3.60, there is more stray light, the stray light energy is higher, and the performance is poor. 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, in this application, by constraining 1.72≤fz / (D1s+D1m)≤2.54 and 2.71≤TD / (EP13+CP3)≤3.17, the aperture of each lens is further increased while ensuring the optical performance, thereby reducing the theoretical vignetting phenomenon and improving the uniformity of light intensity within the visual range; at the same time, the rationality of the lens aperture design is ensured, reducing 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 disposed between the third lens and the fourth lens. In a specific embodiment of the present application, the reflective element is disposed on the first side surface of the fourth lens.

[0055] In this embodiment, the axial interval 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. Reasonable control of 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, reduce calibration time, improve production efficiency, and at the same time 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 and the outer diameter D0s of the first side surface of the lens barrel satisfy: 3.12≤f1 / D0s≤4.61. Reasonable control of the range of this conditional expression can enhance the resolution of the visual system and make the image more delicate. At the same time, it is ensured that the first lens can receive the large-angle light from the first side and the lens barrel will not block the light, which is conducive to improving the imaging quality of the edge area and reducing blur or distortion.

[0057] In this embodiment, the inner diameter d1m of the second side surface of the first spacing element and the axial distance T12 from the second side surface of the first lens to the first side surface of the second lens satisfy: 11.23≤d1m / T12≤15.17. Reasonable control of the range of this conditional expression is conducive to reasonable control of the effective aperture of the first lens within a reasonable range, which can ensure the transmission efficiency of light between the first lens and the second lens, reduce light energy loss, and increase light flux; at the same time, it can reduce the deformation of the lens or spacing element caused by heat accumulation and ensure performance stability.

[0058] In this embodiment, the inner diameter d3s of the first side surface of the third spacer element and the curvature radius R6 of the second side surface of the third lens satisfy: -1.34≤d3s / R6≤-1.19. Reasonable control of the range of this conditional expression can, on the one hand, improve the compatibility of the third spacer element and the third lens, simplify the assembly of the third lens and the third spacer element, and improve production efficiency and consistency; on the other hand, it can reduce the surface sensitivity of the third lens and improve the processing yield.

[0059] In this embodiment, 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: -4.84≤f23 / (D3s+D3m)≤-4.45. By properly controlling the range of this conditional expression and adjusting the light path through the lens combination with a negative focal length, the edge distortion can be suppressed while the field of view angle is expanded, which is suitable for the visual system's requirement for a wide viewing angle; at the same time, the structural strength of the third spacing element can be ensured to prevent the structure from being fragile due to being too small or the weight from being increased due to being too large.

[0060] In this embodiment, the inner diameter d0m of the second side surface of the lens barrel and the curvature radius R8 of the second side surface of the fourth lens satisfy: -2.79≤d0m / R8≤-1.78. Reasonable control of the range of this conditional expression can ensure that the light can be more accurately focused on the retina when passing through the fourth lens, thereby reducing blur and ghosting phenomena and improving the clarity of the image; at the same time, it improves wearing comfort and reduces eye pressure or discomfort.

[0061] In this embodiment, the effective focal length f4 of the fourth lens and the inner diameter d3m of the second side surface of the third spacing element satisfy: 1.81≤f4 / d3m≤8.26. Reasonable control of the range of this conditional expression 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, the third spacing element blocks non-imaging light without blocking the imaging light, reduces the influence of stray light on imaging, reduces ghosting and glare, and improves 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: 9.67≤d0s / EPD≤10.91. Reasonable control of the range of this conditional expression is conducive to the visual system supporting a wider field of view or a larger incident light beam, better allowing the edge light to pass stably, reducing the shielding of the incident light by the lens barrel, thereby improving the imaging quality; at the same time, it allows the use of low thermal expansion coefficient materials, leaving sufficient deformation redundancy or compatible with active heat dissipation design, and reducing the fluctuation of optical performance caused by temperature changes.

[0063] In this embodiment, the axial 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: 2.35mm≤EP13×|f2 / f3|≤12.56mm. Reasonable control of the range of this conditional expression is conducive to the visual system providing a more realistic virtual reality experience, allowing the wearer to experience a more natural and three-dimensional visual effect; at the same time, it ensures that there is no sudden change in the convergence or divergence transmission of light in the visual system, ensuring that the field curvature is relatively small and easy to have a large depth of focus.

[0064] In this embodiment, the axial interval 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. Reasonable control of the range of this conditional expression reduces the sensitivity of the center thickness and edge thickness of the first lens and the structural thickness of the first side end of the lens barrel, improves the assembly stability of the first lens and the lens barrel, and improves the overall yield; at the same time, the mechanical strength requirements of the first spacing element are relatively low, which is conducive to reducing costs.

[0065] In this embodiment, the outer diameter D0m of the second side surface of the lens barrel satisfies the effective focal length f of the visual system: 2.02≤D0m / f≤2.45. Reasonable control of the range of this conditional expression allows each lens in the visual system to have a gentler curvature, which is conducive to reducing the generation of aberrations and helps the light passing through the lens to be refracted more smoothly, reducing aberrations; at the same time, the field of view angle and magnification are balanced, ensuring that the image seen by the user has a sufficiently large field of view, and does not reduce the image quality or require a higher screen resolution due to excessive magnification.

[0066] In this embodiment, the inner diameter d1s of the first side of the first spacing element and the axial spacing L from the first side of the lens barrel to the second side of the lens barrel satisfy: 1.72≤d1s / L≤2.16. The range of this conditional expression is reasonably controlled so that the ratio of the size of the lens barrel along the optical axis to the size of the scene is within a reasonable range, ensuring that the weight difference and thickness difference along the optical axis and radial direction are relatively small, which is ergonomic; at the same time, the assembly difficulty of the visual system is reduced, and the process yield is significantly improved.

[0067] In this embodiment, the inner diameter d3s of the first side of the third spacer element, the inner diameter d1s of the first side 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: 2.12≤(d3s-d1s) / (CT2+CT3)≤2.96. The range of this conditional expression is reasonably controlled, so that the apertures of the first lens to the third lens increase slowly in sequence, and the total length of the system is relatively small, which minimizes the load on the bridge of the nose; it is convenient for users to wear, reduces the sensitivity to the position of the eyeball, and improves 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 spacing 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 glued to form a glued 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: 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: 1.81≤f4 / d3m≤8.26.

[0070] The visual system of the present application is composed of a lens barrel and four lenses arranged in the lens barrel, multiple spacing elements, a polarizer, a reflective polarizing element, a quarter wave plate and a reflective element. By reasonably setting the focal length and surface shape of each lens, the positions of the first spacing element, the third spacing element, the polarizer, the reflective polarizing element, the quarter wave plate and the reflective element, and setting the second lens and the third lens to be glued to form a glued 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, realizing the compression of the total optical length, and realizing lightness and thinness. However, in this case, affected by the size of the lens, the light in the visual system is reflected and scattered multiple times, forming new stray light. Therefore, in the present application, by constraining 1.72≤fz / (D1s+D1m)≤2.54 and 1.81≤f4 / d3m≤8.26, the aperture of each lens is further increased while ensuring the optical performance, thereby reducing the theoretical vignetting phenomenon and improving the uniformity of light intensity within the visual range; at the same time, the rationality of the lens aperture design is ensured, and the risk of stray light and ghost images caused by improper lens aperture design is reduced; at the same time, the loss of light energy can be reduced, making the illumination of the image surface more uniform, especially improving the brightness consistency of the edge area; at the same time, it is ensured that the non-imaging light is blocked without blocking the imaging light, thereby reducing the influence of stray light on imaging, reducing ghost images and glare, and improving 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 by software and / or tools such as ZEMAX, CODEV, etc. In the process of simulation using the above software and / or tools, the surface profile of each lens can be simulated and appropriately adjusted according to the surface profile of 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 the present application may use multiple lenses, such as the four lenses mentioned above. In the present application, at least one of the mirror surfaces of each lens is an aspherical mirror surface. The characteristics of an aspherical lens are: the curvature changes continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens with a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has a better curvature radius characteristic, and has the advantages of improving distortion aberration and improving astigmatism aberration. After using an aspherical lens, the aberration that occurs during imaging can be eliminated as much as possible, thereby improving the imaging quality.

[0075] However, those skilled in the art should understand that, without departing from the technical solution claimed in the present application, the number of lenses constituting the visual system can be changed to obtain the various results and advantages described in this specification. For example, although four lenses are used as an example in the embodiment, the visual system is not limited to including four lenses. If necessary, the visual system may 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 indicated in the figure to clearly and intuitively understand the meaning of the parameters. In order to facilitate the description of the visual system and the surface shape of the specific lens, these parameters will no longer be reflected in the drawings when describing the specific embodiments later.

[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 embodiment 1, there are three examples of embodiment 1-1, embodiment 1-2, and embodiment 1-3, in embodiment 2, there are three examples of embodiment 2-1, embodiment 2-2, and embodiment 2-3, and in embodiment 3, there are three examples of embodiment 3-1, embodiment 3-2, and embodiment 3-3. The parameters of the optical system in the visual system in the three examples of 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, the spacing distance between the lenses, and the coefficients of high-order terms are the same, but the parameters such as the thickness, inner diameter, and outer diameter of the lens barrel, the first spacing element, and the third spacing 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] Embodiment 1

[0081] like Figures 2 to 5 As shown, the visual system of embodiment 1 is described. Figure 2 The schematic diagram of the structure of the visual system of Example 1-1 is shown. Figure 3 The schematic diagram of the structure of the visual system of Embodiment 1-2 is shown, Figure 4 The schematic diagram of the structure of the visual system of Examples 1-3 is shown.

[0082] like Figures 2 to 4As shown, the visual system includes a lens barrel P0 and a first lens E1, a first spacing element P1, a second lens E2, a third lens E3, a third spacing element P3, and a fourth lens E4 which are sequentially arranged in the lens barrel P0 from the first side to the second side along the optical axis. A polarizing plate LP, a reflective polarizing element RP, and a quarter wave plate QWP are also sequentially arranged between the first lens E1 and the second lens E2 from the first side to the second side, and a reflecting element BS is also arranged between the third lens E3 and the fourth lens E4. The second lens E2 and the third lens E3 are cemented to form a cemented lens.

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

[0084] In this embodiment, the 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, and then is incident on the reflective polarizing element RP. After being reflected by the reflective polarizing element RP, it is transmitted toward the display side. Then, the light is sequentially transmitted through the quarter-wave plate QWP, the second lens E2, and the third lens E3, and then is incident on the reflective element BS. After being reflected by the reflective element BS, it is transmitted toward the human eye side. Then, the light is sequentially transmitted through the third lens E3, the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, the polarizing plate LP, and the first lens E1, and then is incident on the human eye for imaging.

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

[0086] like Figure 3 , which 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 spacing element is the same as that of Example 1-1, and the relevant description in Example 1-1 may be referred to, and will not be repeated here.

[0087] like Figure 4 , which 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 spacing element is the same as that of Example 1-1, and the relevant description in Example 1-1 may be referred to, and 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 Embodiment 1, the first side surface of the first lens is a concave surface, and the second side surface of the first lens is a convex surface. The first side surface of the second lens is a concave surface, and the second side surface of the second lens is a convex surface. The first side surface of the third lens is a concave surface, and the second side surface of the third lens is a convex surface. The first side surface of the fourth lens is a concave surface, and the second side surface of the fourth lens is a convex surface.

[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 parameter table of the visual system of Example 1, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm).

[0094] Table 3

[0095]

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

[0097] Formula (1).

[0098] Wherein, x is the distance vector height of the aspheric surface 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, that is, the paraxial curvature c is the reciprocal of the curvature radius R in the above Table 3; k is the cone coefficient; Ai is the correction coefficient of the i-th order of the aspheric surface. The following Table 4 gives the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 that can be used for each aspheric surface 2-24 in Example 1.

[0099] Table 4

[0100]

[0101] Figure 5 The MTF curve diagram of the visual system of the first embodiment is shown. As can be seen from the figure, the MTF curve is relatively high, indicating that the imaging quality at this spatial frequency is relatively good.

[0102] Embodiment 2

[0103] like Figures 6 to 9 As shown, the visual system of embodiment 2 is described. Figure 6 The schematic diagram of the structure of the visual system of Example 2-1 is shown. Figure 7 The schematic diagram of the structure of the visual system of Example 2-2 is shown. Figure 8 A schematic diagram of the structure 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 a first lens E1, a first spacing element P1, a second lens E2, a third lens E3, a third spacing element P3, and a fourth lens E4 which are sequentially arranged in the lens barrel P0 from the first side to the second side along the optical axis. A polarizing plate LP, a reflective polarizing element RP, and a quarter wave plate QWP are also sequentially arranged between the first lens E1 and the second lens E2 from the first side to the second side, and a reflecting element BS is also arranged between the third lens E3 and the fourth lens E4. The second lens E2 and the third lens E3 are cemented to form a cemented lens.

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

[0106] In this embodiment, the 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, and then is incident on the reflective polarizing element RP. After being reflected by the reflective polarizing element RP, it is transmitted toward the display side. Then, the light is sequentially transmitted through the quarter-wave plate QWP, the second lens E2, and the third lens E3, and then is incident on the reflective element BS. After being reflected by the reflective element BS, it is transmitted toward the human eye side. Then, the light is sequentially transmitted through the third lens E3, the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, the polarizing plate LP, and the first lens E1, and then is incident on the human eye for imaging.

[0107] like Figure 6, which is a schematic diagram of the structure of the visual system of Example 2-1. In this example, the first side surface and the second side surface of the first spacing element P1 are respectively supported by the second side surface of the first lens and the first side surface of the second lens. The first side surface and the second side surface of the third spacing element P3 are respectively supported by the second side surface of the third lens and the first side surface of the fourth lens.

[0108] like Figure 7 , which 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 spacing element is the same as that of Example 2-1, and the relevant description in Example 2-1 may be referred to, and will not be repeated here.

[0109] like Figure 8 , which 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 spacing element is the same as that of Example 2-1, and the relevant description in Example 2-1 may be referred to, 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 the second embodiment, the first side surface of the first lens is a concave surface, and the second side surface of the first lens is a convex surface. The first side surface of the second lens is a concave surface, and the second side surface of the second lens is a convex surface. The first side surface of the third lens is a concave surface, and the second side surface of the third lens is a convex surface. The first side surface of the fourth lens is a concave surface, and the second side surface of the fourth lens is a convex surface.

[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 axial 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 parameter table of the visual system of Example 2, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm).

[0116] Table 6

[0117]

[0118] Table 7 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 2.

[0119] Table 7

[0120]

[0121] Fig. 9 The MTF curve diagram of the visual system of the second embodiment is shown. As can be seen from the figure, the MTF curve is relatively high, indicating that the imaging quality at this spatial frequency is relatively good.

[0122] Embodiment 3

[0123] like Figures 10 to 13 As shown, the visual system of embodiment 3 is described. Fig.10 The schematic diagram of the structure of the visual system of Example 3-1 is shown. Fig.11 The schematic diagram of the structure of the visual system of Example 3-2 is shown. Fig.12 A schematic diagram of the structure 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 a first lens E1, a first spacing element P1, a second lens E2, a third lens E3, a third spacing element P3, and a fourth lens E4 which are sequentially arranged in the lens barrel P0 from the first side to the second side along the optical axis. A polarizing plate LP, a reflective polarizing element RP, and a quarter wave plate QWP are also sequentially arranged between the first lens E1 and the second lens E2 from the first side to the second side, and a reflecting element BS is also arranged between the third lens E3 and the fourth lens E4. The second lens E2 and the third lens E3 are cemented to form a cemented lens.

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

[0126] In this embodiment, the 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, and then is incident on the reflective polarizing element RP. After being reflected by the reflective polarizing element RP, it is transmitted toward the display side. Then, the light is sequentially transmitted through the quarter-wave plate QWP, the second lens E2, and the third lens E3, and then is incident on the reflective element BS. After being reflected by the reflective element BS, it is transmitted toward the human eye side. Then, the light is sequentially transmitted through the third lens E3, the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, the polarizing plate LP, and the first lens E1, and then is incident on the human eye for imaging.

[0127] like Fig.10 , which is a schematic diagram of the structure of the visual system of Example 3-1. In this example, the first side surface and the second side surface of the first spacing element P1 are respectively supported by the second side surface of the first lens and the first side surface of the second lens. The first side surface and the second side surface of the third spacing element P3 are respectively supported by the second side surface of the third lens and the first side surface of the fourth lens.

[0128] like Fig.11 , which 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 spacing element is the same as that of Example 3-1, and the relevant description in Example 3-1 may be referred to, and will not be repeated here.

[0129] like Fig.12 , which 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 spacing element is the same as that of Example 3-1, and the relevant description in Example 3-1 may be referred to, 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 the third embodiment, the first side surface of the first lens is a concave surface, and the second side surface of the first lens is a convex surface. The first side surface of the second lens is a concave surface, and the second side surface of the second lens is a convex surface. The first side surface of the third lens is a concave surface, and the second side surface of the third lens is a convex surface. The first side surface of the fourth lens is a concave surface, and the second side surface of the fourth lens is a convex surface.

[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 parameter table of the visual system of Example 3, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm).

[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] Fig.13 The MTF curve diagram of the visual system of the third embodiment is shown. As can be seen from the figure, the MTF curve is relatively high, indicating that the imaging quality at this spatial frequency is relatively good.

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

[0143] Table 11

[0144]

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

[0146] Table 12

[0147]

[0148] The present application also provides an imaging device, whose electronic photosensitive element can be a photosensitive coupled device (CCD) or a complementary metal oxide semiconductor element (CMOS). The imaging device can be an independent imaging device such as a digital camera, or an imaging module integrated in 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 above-described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work 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, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0152] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0153] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A visual system, characterized in that: The invention comprises a lens barrel and a lens group and a spacer element group arranged in the lens barrel, The lens group is composed of four lenses, a polarizing plate, 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 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 a concave surface, and the second side surface is a convex surface; the first side surface of the second lens is a concave 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 concave surface, and the second side surface is a convex surface; the second lens is glued to the third lens to form a glued 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 a second side surface of the first lens, and a third spacer element located between the third lens and the fourth lens and abutting against a 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 spacing element and the outer diameter D1m of the second side surface of the first spacing element satisfy the following: 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 spacing element to the first side surface of the third spacing element, and the maximum axial thickness CP3 of the third spacing 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, characterized in that: 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, characterized in that: An inner diameter d1m of the second side surface of the first spacing 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, characterized in that: An inner diameter d3s of the first side surface of the third spacing element and a curvature radius R6 of the second side surface of the third lens satisfy: -1.34≤d3s / R6≤-1.

19.

6. The visual system according to claim 1, characterized in that: 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: -4.84≤f23 / (D3s+D3m)≤-4.

45.

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

26.

9. The visual system according to claim 1, characterized in that: 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, characterized in that: 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: 2.35mm≤EP13×|f2 / f3|≤12.56mm.

11. 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 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.

12. The visual system according to claim 1, characterized in that: 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.

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 of the lens barrel 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 of the third spacing element, the inner diameter d1s of the first side of the first spacing 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: 2.12≤(d3s-d1s) / (CT2+CT3)≤2.96.

Images