Visual system

Abstract

The invention provides a visual system. The visual system comprises a lens cone, a lens group and a spacing element group, the lens group and the spacing element group are arranged in the lens cone, and the lens group is composed of four lenses, a polaroid, a reflective polarizing element, a quarter-wave plate and a reflective element. The four lenses are sequentially a first lens with positive focal power, a second lens with negative focal power, a third lens with negative focal power and a fourth lens with positive focal power from the first side to the second side; f23 / d3s is more than or equal to-9.75 and less than or equal to-8.72; f / (CP1 + EP13) is more than 5.00 and less than 5.40. The problem that stray light is serious due to the fact that a four-piece type visual system in the prior art is provided with a bonding lens and a reflecting part to meet the requirement for structure compactness is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical imaging devices, and more particularly, to a visual system. Background Art

[0002] In the current field of AR / VR optical imaging devices, especially in the design of Head-Mounted Displays (HMDs), four-piece visual systems are favored because of their few lens elements and ability to provide high-quality images. However, as the devices using them are gradually developing towards being thinner, lighter, and more portable, four-piece visual systems are also facing more severe challenges.

[0003] Currently, to meet the requirement of structural compactness, four-piece visual systems compress the interval between adjacent lenses and fold the optical path by reasonably arranging cemented lenses and reflectors, thereby reducing the overall length and ensuring structural compactness. However, in this case, the compact structure leads to an increase in the reflection or refraction of light at the lens edges, and thus an increase in stray light, which seriously interferes with imaging, affects the clarity of imaging, and reduces the imaging quality of the visual system.

[0004] That is to say, the four-piece visual system in the prior art has the problem that the arrangement of cemented lenses and reflectors is used to meet the requirement of structural compactness, resulting in serious stray light. Summary of the Invention

[0005] The main object of the present invention is to provide a visual system to solve the problem that the four-piece visual system in the prior art arranges cemented lenses and reflectors to meet the requirement of structural compactness, resulting in serious stray light.

[0006] To achieve the above object, according to one aspect of the present invention, a visual system is provided, which includes a lens barrel and a lens group and a spacer element group disposed in the lens barrel. The lens group is composed of four lenses, a polarizer, a reflective polarizing element, a quarter-wave plate, and a reflective element. The four lenses are, in order from the first side to the second side, a first lens with a positive optical power, a second lens with a negative optical power, a third lens with a negative optical power, and a fourth lens with a positive optical power. The first side of the first lens is concave, and the second side is convex; the first side of the second lens is concave, and the second side is convex; the first side of the third lens is concave, and the second side is convex; the first side of the fourth lens is concave, and the second side 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 sequentially disposed on the second side of the first lens 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 of the first lens, and a third spacer element located between the third lens and the fourth lens and abutting against the second side of the third lens; wherein, the combined focal length f23 of the second lens and the third lens and the inner diameter d3s of the first side of the third spacer element satisfy: -9.75 ≤ f23 / d3s ≤ -8.72; the effective focal length f of the visual system, the maximum axial thickness CP1 of the first spacer element, and the on-axis interval EP13 from the second side of the first spacer element to the first side of the third spacer element satisfy: 5.00 < f / (CP1 + EP13) < 5.40.

[0007] According to another aspect of the present invention, a visual system is provided, which includes a lens barrel and a lens group and a spacer 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, in order from the first side to the second side, a first lens with a positive optical power, a second lens with a negative optical power, a third lens with a negative optical power, and a fourth lens with a positive optical power. The first side of the first lens is concave, and the second side is convex; the first side of the second lens is concave, and the second side is convex; the first side of the third lens is concave, and the second side is convex; the first side of the fourth lens is concave, and the second side 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 sequentially arranged on the second side of the first lens 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 abutting against the second side of the first lens, and a third spacer element located between the third lens and the fourth lens and abutting against the second side of the third lens; wherein, the combined focal length f23 of the second lens and the third lens and the inner diameter d3s of the first side of the third spacer element satisfy: -9.75 ≤ f23 / d3s ≤ -8.72; the outer diameter D0m of the second side of the lens barrel, the inner diameter d0s of the first side of the lens barrel, and the axial interval EP13 from the second side of the first spacer element to the first side of the third spacer element satisfy: 3.06 ≤ (D0m - d0s) / EP13 ≤ 3.93.

[0008] Further, the effective focal length f1 of the first lens, the inner diameter d1s of the first side of the first spacer element, and the inner diameter d1m of the second side of the first spacer element satisfy: 2.30 ≤ f1 / (d1s + d1m) ≤ 2.54.

[0009] Further, the combined focal length fz of the first lens, the polarizer, the reflective polarizing element, and the quarter-wave plate and the inner diameter d0s of the first side of the lens barrel satisfy: 4.49 ≤ fz / d0s ≤ 5.15.

[0010] Further, the radius of curvature R2 of the second side of the first lens and the axial interval EP01 from the first side of the lens barrel to the first side of the first spacer element satisfy: -8.71 ≤ R2 / EP01 ≤ -6.27.

[0011] Further, the outer diameter D1m of the second side of the first spacer element, the inner diameter d1m of the second side of the first spacer element, and the central thickness CT2 of the second lens on the optical axis of the visual system satisfy: 4.50 ≤ (D1m - d1m) / CT2 ≤ 6.23.

[0012] Furthermore, the following condition is satisfied among the outer diameter D3m of the second side surface of the third spacer element, the inner diameter d3m of the second side surface of the third spacer element, and the on-axis distance T34 from the second side surface of the third lens to the first side surface of the fourth lens: 1.09 ≤ (D3m - d3m) / T34 ≤ 1.56.

[0013] Furthermore, the following condition is satisfied among the maximum axial thickness CP3 of the third spacer element, the effective focal length f3 of the third lens, and the effective focal length f4 of the fourth lens: -0.40 mm ≤ CP3 × (f3 / f4) ≤ -0.11 mm.

[0014] Furthermore, the following condition is satisfied between the inner diameter d0m of the second side surface of the lens barrel and the central thickness CT4 of the fourth lens on the optical axis of the visual system: 18.55 ≤ d0m / CT4 ≤ 19.18.

[0015] Furthermore, the following condition is satisfied among the outer diameter D0m of the second side surface of the lens barrel, the inner diameter d0s of the first side surface of the lens barrel, and the on-axis interval EP13 from the second side surface of the first spacer element to the first side surface of the third spacer element: 3.06 ≤ (D0m - d0s) / EP13 ≤ 3.93.

[0016] Furthermore, the following condition is satisfied among the curvature radius R1 of the first side surface of the first lens, the curvature radius R8 of the second side surface of the fourth lens, and the on-axis distance L from the first side surface of the lens barrel to the second side surface of the lens barrel: -4.27 ≤ (R1 + R8) / L ≤ -3.50.

[0017] Furthermore, the following condition is satisfied among the outer diameter D1s of the first side surface of the first spacer element, the outer diameter D3s of the first side surface of the third spacer element, and the on-axis distance TD from the first side surface of the first lens to the second side surface of the fourth lens: 6.00 ≤ (D1s + D3s) / TD ≤ 6.27.

[0018] Furthermore, the following condition is satisfied between the outer diameter D0s of the first side surface of the lens barrel and the effective focal length f of the visual system: 1.69 ≤ D0s / f ≤ 1.98.

[0019] Furthermore, the following condition is satisfied between the inner diameter d1s of the first side surface of the first spacer element and the central thickness CT1 of the first lens on the optical axis of the visual system: 11.71 ≤ d1s / CT1 ≤ 12.66.

[0020] Furthermore, the following condition is satisfied among the on-axis distance L from the first side surface of the lens barrel to the second side surface of the lens barrel, the central thickness CT2 of the second lens on the optical axis of the visual system, and the central thickness CT3 of the third lens on the optical axis: 4.91 ≤ L / (CT2 + CT3) ≤ 5.69.

[0021] Applying the technical solution of the present invention, the visual system of this application consists of a lens barrel and four lenses, multiple spacer elements, a polarizer, a reflective polarizing element, a quarter-wave plate, and a reflective element arranged in the lens barrel. 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 polarizing element, the quarter-wave plate, and the reflective element, and gluing 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, planning the refraction and reflection of the optical path between the first lens and the fourth lens is beneficial to folding the optical path, thereby reducing the overall length of the visual system and meeting the requirement of structural compactness. However, in this case, the compact structure leads to an increase in the reflection or refraction of light at the edge of the lens, and further leads to an increase in stray light, making the interference of stray light on imaging relatively serious, affecting the clarity of imaging, and reducing the imaging quality of the visual system. Therefore, in this application, by constraining -9.75 ≤ f23 / d3s ≤ -8.72 and 5.00 < f / (CP1 + EP13) < 5.40, while ensuring the overall structural compactness of the visual system, the processability of the first spacer element and the third spacer element is ensured. At the same time, the third spacer element can effectively intercept stray light, reduce the stray light interference at the third spacer element, improve the imaging quality of the visual system, and ensure that users obtain clear imaging and a good experience. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0023] Figure 1 Shows the dimension marking diagram of the visual system of an optional embodiment of the present invention;

[0024] Figure 2 Shows the structural schematic diagram of the visual system of Embodiment 1-1 of the present invention;

[0025] Figure 3 Shows the structural schematic diagram of the visual system of Embodiment 1-2 of the present invention;

[0026] Figure 4 Shows the structural schematic diagram of the visual system of Embodiment 1-3 of the present invention;

[0027] Figure 5 Shows the MTF curve diagram of the visual system of Embodiment 1 of the present invention;

[0028] Figure 6 Shows the structural schematic diagram of the visual system of Embodiment 2-1 of the present invention;

[0029] Figure 7Shows a schematic structural diagram of the visual system of Embodiment 2-2 of the present invention;

[0030] Figure 8 Shows a schematic structural diagram of the visual system of Embodiment 2-3 of the present invention;

[0031] Figure 9 Shows the MTF curve graph of the visual system of Embodiment 2 of the present invention;

[0032] Figure 10 Shows a schematic structural diagram of the visual system of Embodiment 3-1 of the present invention;

[0033] Figure 11 Shows a schematic structural diagram of the visual system of Embodiment 3-2 of the present invention;

[0034] Figure 12 Shows a schematic structural diagram of the visual system of Embodiment 3-3 of the present invention;

[0035] Figure 13 Shows the MTF curve graph of the visual system of Embodiment 3 of the present invention;

[0036] Figure 14 Shows the stray light energy schematic diagram when the visual system of Solution 1 of the present application satisfies f23 / d3s = -8.77 and f / (CP1+EP13) = 5.20;

[0037] Figure 15 Shows the stray light energy schematic diagram when the visual system of Comparative Example 1 satisfies f23 / d3s = -10.20 and f / (CP1+EP13) = 4.20;

[0038] Figure 16 Shows the stray light energy schematic diagram when the visual system of Comparative Example 2 satisfies f23 / d3s = -8.10 and f / (CP1+EP13) = 5.80.

[0039] Among them, the above-mentioned 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 element; P3, third spacer element; LP, polarizer; RP, reflective polarizing element; QWP, quarter-wave plate; BS, reflective element; IMG, image plane. Detailed implementation manners

[0041] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the 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 those of ordinary skill in the technical field to which this application pertains.

[0043] In the present invention, unless otherwise stated, the orientation terms such as "upper, lower, top, bottom" are generally with respect to the direction shown in the drawings, or with respect to the component itself in the vertical, perpendicular or gravitational direction; similarly, for the sake of easy understanding and description, "inner, outer" refer to the inner and outer of the contour of each component itself, but the above orientation terms are not used to limit the present invention.

[0044] It should be noted that in this specification, the expressions such as first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0045] In the drawings, for the sake of convenience of illustration, the thickness, size and shape of the lens have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0046] In this text, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The judgment of the surface shape in the paraxial region can be based on the judgment method of those with ordinary knowledge in this field, and the positive and negative of the R value (R refers to the radius of curvature in the paraxial region, usually the R value on the lens database (lens data) in optical software) are used to judge the convexity and concavity. Taking the first side as an example, when the R value is positive, it is judged to be convex, and when the R value is negative, it is judged to be concave; taking the second side as an example, when the R value is positive, it is judged to be concave, and when the R value is negative, it is judged to be convex. When the R value is infinite, it is judged to be a plane. In this 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.

[0047] In order to solve the problem that the four-piece visual system in the prior art has serious stray light due to the need to set cemented lenses and reflectors to meet the requirement of structural compactness, the present invention provides a visual system.

[0048] Such as Figures 1 to 14As shown, in an alternative embodiment of the present application, a visual system is provided, which includes a lens barrel and a lens group and a spacer element group disposed in the lens barrel. The lens group is composed of four lenses, a polarizer, a reflective polarizing element, a quarter-wave plate, and a reflective element. The four lenses are, in order from the first side to the second side, a first lens with a positive optical power, a second lens with a negative optical power, a third lens with a negative optical power, and a fourth lens with a positive optical power. The first side of the first lens is concave, and the second side is convex; the first side of the second lens is concave, and the second side is convex; the first side of the third lens is concave, and the second side is convex; the first side of the fourth lens is concave, and the second side 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 sequentially disposed on the second side of the first lens in a direction away from the first lens; the reflective element is disposed between the third lens and the fourth lens.

[0049] The spacer element group includes a first spacer element located between the first lens and the second lens and abutting against the second side of the first lens, and a third spacer element located between the third lens and the fourth lens and abutting against the second side of the third lens; wherein, the combined focal length f23 of the second lens and the third lens and the inner diameter d3s of the first side of the third spacer element satisfy: -9.75 ≤ f23 / d3s ≤ -8.72; the effective focal length f of the visual system, the maximum axial thickness CP1 of the first spacer element, and the on-axis spacing EP13 from the second side of the first spacer element to the first side of the third spacer element satisfy: 5.00 < f / (CP1 + EP13) < 5.40.

[0050] The visual system of the present application consists of a lens barrel and four lenses, multiple spacer elements, a polarizer, a reflective polarizing element, a quarter-wave plate, and a reflective element disposed in the lens barrel. By reasonably setting the optical powers and surface profiles of the lenses, the positions of the first spacer element, the third spacer element, the polarizer, the reflective polarizing element, the quarter-wave plate, and the reflective element, and gluing 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, planning the refraction and reflection of the optical path between the first lens and the fourth lens is beneficial to folding the optical path, thereby reducing the overall length of the visual system and meeting the requirements of structural compactness. However, in this case, the compact structure leads to an increase in the reflection or refraction of light at the lens edges, which in turn leads to an increase in stray light, resulting in a more serious interference of stray light on imaging, affecting the clarity of imaging, and reducing the imaging quality of the visual system. Therefore, in the present application, by constraining -9.75 ≤ f23 / d3s ≤ -8.72 and 5.00 < f / (CP1 + EP13) < 5.40, while ensuring the overall structural compactness of the visual system, the processability of the first spacer element and the third spacer element is ensured. At the same time, the third spacer element can effectively intercept stray light, reduce the stray light interference at the third spacer element, improve the imaging quality of the visual system, and ensure that users obtain clear imaging and a good experience.

[0051] In addition, referring to Table 1 below, Figures 14 to 16 as shown, Figure 14 Figure 7 shows the schematic diagram of the stray light energy when the visual system of Solution 1 of the present application satisfies f23 / d3s = -8.77 and f / (CP1 + EP13) = 5.20. Figure 15 Figure 8 shows the schematic diagram of the stray light energy when the visual system of Comparative Example 1 satisfies f23 / d3s = -10.20 and f / (CP1 + EP13) = 4.20. Figure 16 Figure 9 shows the schematic diagram of the stray light energy when the visual system of Comparative Example 2 satisfies f23 / d3s = -8.10 and f / (CP1 + EP13) = 5.80.

[0052] From Figures 14 to 16It can be known that when the visual system satisfies f23 / d3s = -8.77 and f / (CP1 + EP13) = 5.20, there is less stray light, the stray light energy is lower, and the performance is better. When the visual system satisfies f23 / d3s = -10.20, f / (CP1 + EP13) = 4.20 or f23 / d3s = -8.10, f / (CP1 + EP13) = 5.80, there is more stray light, the stray light energy is higher, and the performance is worse. Thus, it can be seen that when -9.75 ≤ f23 / d3s ≤ -8.72 and 5.00 < f / (CP1 + EP13) < 5.40 are satisfied, there is less stray light, the stray light energy is lower, and the performance is better. Therefore, in this application, by restricting -9.75 ≤ f23 / d3s ≤ -8.72 and 5.00 < f / (CP1 + EP13) < 5.40, while ensuring the overall structure of the visual system is compact, the processability of the first spacer element and the third spacer element is ensured. At the same time, the third spacer element can effectively intercept stray light, reduce the stray light interference at the third spacer element, improve the imaging quality of the visual system, and ensure that users obtain clear imaging and a good experience.

[0053] Table 1

[0054] Solution 1 of this application Comparative Example 1 Comparative Example 2 f23 / d3s -8.77 -10.20 -8.10 f / (CP1 + EP13) 5.20 4.20 5.80

[0055] It should be noted that a reflective element can be arranged between the third lens and the fourth lens. In the specific implementation manner of this application, the reflective element is arranged on the first side surface of the fourth lens.

[0056] In this embodiment, the effective focal length f1 of the first lens, the inner diameter d1s of the first side surface of the first spacer element, and the inner diameter d1m of the second side surface of the first spacer element satisfy: 2.30 ≤ f1 / (d1s + d1m) ≤ 2.54. Reasonably controlling the range of this conditional formula can not only ensure that the effective focal length of the first lens is positive to realize the focusing optical path of the visual system, but also control the inner diameters of the first side surface and the second side surface of the first spacer element within a reasonable range, avoid the first spacer element intercepting the transmission of effective light, ensure the light transmission amount on both sides of the first spacer element, and ensure the illuminance of the final image.

[0057] In this embodiment, the combined focal length fz of the first lens, the polarizing plate, the reflective polarizing element, and the quarter-wave plate and the inner diameter d0s of the first side surface of the lens barrel satisfy: 4.49 ≤ fz / d0s ≤ 5.15. Reasonably controlling the range of this conditional formula can not only ensure that the combined focal length of the first lens, the polarizing plate, the reflective polarizing element, and the quarter-wave plate is positive to realize the smooth transition of the optical path, which is beneficial to the appropriate focusing of light before entering the human eye, but also control the inner diameter of the first side surface of the lens barrel within a reasonable range, ensure that there is sufficient contact area between the lens barrel and the first lens, and thus ensure the assembly stability of the visual system.

[0058] In this embodiment, the radius of curvature R2 of the second side surface of the first lens and the on-axis spacing EP01 from the first side surface of the lens barrel to the first side surface of the first spacer element satisfy: -8.71 ≤ R2 / EP01 ≤ -6.27. By reasonably controlling the range of this conditional expression, it is possible to ensure that the radius of curvature of the second side surface of the first lens is negative to achieve stable deflection of the optical path, which is beneficial to ensuring the rationality of the surface shape of the first lens. It can also control the on-axis spacing from the first side surface of the lens barrel to the first side surface of the first spacer element within a reasonable range, ensure the processing feasibility of the lens barrel and the first spacer element, and ensure the stable cooperation of the first lens with the lens barrel and the first spacer element, thereby improving the assembly stability of the visual system.

[0059] In this embodiment, the outer diameter D1m of the second side surface of the first spacer element, the inner diameter d1m of the second side surface of the first spacer element, and the central thickness CT2 of the second lens on the optical axis of the visual system satisfy: 4.50 ≤ (D1m - d1m) / CT2 ≤ 6.23. By reasonably controlling the range of this conditional expression, it is possible to ensure that the second side surface of the first spacer element has sufficient radial width for the nozzle to pick up and rest on, ensure the stable assembly of the first spacer element and the second lens, improve the assembly stability of the visual system, and also control the central thickness of the second lens on the optical axis within a reasonable range to ensure the processing feasibility of the second lens.

[0060] In this embodiment, the outer diameter D3m of the second side surface of the third spacer element, the inner diameter d3m of the second side surface of the third spacer element, and the on-axis distance T34 from the second side surface of the third lens to the first side surface of the fourth lens satisfy: 1.09 ≤ (D3m - d3m) / T34 ≤ 1.56. By reasonably controlling the range of this conditional expression, it is possible to ensure that the second side surface of the third spacer element has sufficient radial width for the nozzle to pick up and rest on, ensure the stable resting of the third spacer element and the fourth lens in the lens barrel, and also control the on-axis distance from the second side surface of the third lens to the first side surface of the fourth lens to ensure the stable transmission of light between the fourth lens and the third lens and guarantee the optical performance of the visual system.

[0061] In this embodiment, the maximum axial thickness CP3 of the third spacer element, the effective focal length f3 of the third lens, and the effective focal length f4 of the fourth lens satisfy: -0.40 mm ≤ CP3×(f3 / f4) ≤ -0.11 mm. By reasonably controlling the range of this conditional expression, it is possible to keep the maximum axial thickness of the third spacer element within a reasonable range to ensure the processing feasibility of the third spacer element, and also control the ratio of the effective focal length of the third lens to the effective focal length of the fourth lens to be negative to ensure that the light can diverge moderately after passing through the fourth lens and the third lens, thereby ensuring the optical path trend of the visual system.

[0062] In this embodiment, the inner diameter d0m of the second side surface of the lens barrel and the central thickness CT4 of the fourth lens on the optical axis of the visual system satisfy: 18.55 ≤ d0m / CT4 ≤ 19.18. Reasonably controlling the range of this conditional expression can not only ensure that the outer shape of the lens barrel is not too large, but also control the central thickness of the fourth lens on the optical axis within a reasonable range, ensure the dimensional rationality of the fourth lens, and ensure the processing feasibility of the fourth lens.

[0063] In this embodiment, the outer diameter D0m of the second side surface of the lens barrel, the inner diameter d0s of the first side surface of the lens barrel, and the on-axis interval EP13 from the second side surface of the first spacer element to the first side surface of the third spacer element satisfy: 3.06 ≤ (D0m - d0s) / EP13 ≤ 3.93. Reasonably controlling the range of this conditional expression can not only ensure the size of the lens barrel and good stability of the lens barrel during test support, but also ensure that the on-axis interval from the second side surface of the first spacer element to the first side surface of the third spacer element is within a reasonable range, avoiding poor assembly stability caused by excessive assembly drop, and ensuring the stable assembly of each structure in the lens barrel.

[0064] In this embodiment, the radius of curvature R1 of the first side surface of the first lens, the radius of curvature R8 of the second side surface of the fourth lens, and the on-axis distance L from the first side surface of the lens barrel to the second side surface of the lens barrel satisfy: -4.27 ≤ (R1 + R8) / L ≤ -3.50. Reasonably controlling the range of this conditional expression reasonably distributes the radii of curvature of the first side surface of the first lens and the second side surface of the fourth lens, and controls the trend of the optical path by controlling the sum of the two to be negative, which is beneficial to controlling the smooth transmission of effective light. At the same time, the on-axis distance from the first side surface of the lens barrel to the second side surface of the lens barrel is limited to ensure that the outer shape of the lens barrel is not too large, thereby ensuring the thinness and lightness of the visual system.

[0065] In this embodiment, the outer diameter D1s of the first side surface of the first spacer element, the outer diameter D3s of the first side surface of the third spacer element, and the on-axis distance TD from the first side surface of the first lens to the second side surface of the fourth lens satisfy: 6.00 ≤ (D1s + D3s) / TD ≤ 6.27. Reasonably controlling the range of this conditional expression limits the on-axis distance from the first side surface of the first lens to the second side surface of the fourth lens, avoiding the situation of too long on-axis length of the lens group, which is beneficial to improving the structural compactness of the visual system. At the same time, the outer diameters of the first side surfaces of the first spacer element and the third spacer element can be controlled to ensure that the outer diameters of the first side surfaces of the first spacer element and the third spacer element are not too large, thereby being beneficial to ensuring that the outer shape of the visual system is not too large and ensuring the miniaturization of the visual system.

[0066] In this embodiment, the outer diameter D0s of the first side surface of the lens barrel and the effective focal length f of the visual system satisfy: 1.69 ≤ D0s / f ≤ 1.98. By reasonably controlling the range of this conditional expression, on the basis of ensuring the overall optical performance of the visual system, the outer diameter of the first side surface of the lens barrel can be controlled within a reasonable range, which is beneficial to ensuring the structural strength of the lens barrel, and then ensuring the stable assembly of each structure in the lens barrel and the assembly stability of the visual system.

[0067] In this embodiment, the inner diameter d1s of the first side surface of the first spacer element and the central thickness CT1 of the first lens on the optical axis of the visual system satisfy: 11.71 ≤ d1s / CT1 ≤ 12.66. By reasonably controlling the range of this conditional expression, both the risk of the first spacer element intercepting effective light rays can be avoided to ensure the light transmittance of the first spacer element, and the central thickness of the first lens on the optical axis can be ensured to be within a reasonable range, which is beneficial to improving the dimensional rationality of the first lens and ensuring the processing feasibility of the first lens.

[0068] In this embodiment, the axial distance L from the first side surface of the lens barrel to the second side surface of the lens barrel, the central thickness CT2 of the second lens on the optical axis of the visual system, and the central thickness CT3 of the third lens on the optical axis satisfy: 4.91 ≤ L / (CT2 + CT3) ≤ 5.69. By reasonably controlling the range of this conditional expression, both the axial distance from the first side surface of the lens barrel to the second side surface of the lens barrel can be ensured to be within a reasonable range to avoid the overall shape of the visual system from being too large, and the central thicknesses of the second lens and the third lens on the optical axis can be controlled to ensure the dimensional rationality of the second lens and the third lens, thereby improving the optical performance and processing feasibility of the second lens and the third lens.

[0069] In addition, in another optional embodiment of the present application, a visual system is further provided, which includes 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 polarizer, a reflective polarizing element, a quarter-wave plate, and a reflective element. The four lenses are, in sequence from the first side to the second side, a first lens with a positive optical power, a second lens with a negative optical power, a third lens with a negative optical power, and a fourth lens with a positive optical power. The first side of the first lens is concave, and the second side is convex; the first side of the second lens is concave, and the second side is convex; the first side of the third lens is concave, and the second side is convex; the first side of the fourth lens is concave, and the second side is convex; the second lens and the third lens are glued together to form a glued lens; the polarizer, the reflective polarizing element, and the quarter-wave plate are arranged on the second side of the first lens 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 abutting against the second side of the first lens and a third spacer element located between the third lens and the fourth lens and abutting against the second side of the third lens; wherein, the combined focal length f23 of the second lens and the third lens and the inner diameter d3s of the first side of the third spacer element satisfy: -9.75 ≤ f23 / d3s ≤ -8.72; the outer diameter D0m of the second side of the lens barrel, the inner diameter d0s of the first side of the lens barrel, and the axial spacing EP13 from the second side of the first spacer element to the first side of the third spacer element satisfy: 3.06 ≤ (D0m - d0s) / EP13 ≤ 3.93.

[0070] 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 optical power 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 refraction and reflection of the light path between the first lens to the fourth lens are planned, which is beneficial to folding the light path, thereby reducing the overall length of the visual system and meeting the requirements of structural compactness. However, in this case, the compact structure leads to an increase in the reflection or refraction of light at the edge of the lens, which in turn leads to an increase in stray light, so that the interference of stray light on imaging is more serious, affecting the clarity of imaging and reducing the imaging quality of the visual system. Therefore, the present application, by constraining -9.75≤f23 / d3s≤-8.72 and 3.06≤(D0m-d0s) / EP13≤3.93, enables the third spacing element to effectively intercept stray light while ensuring the overall structure of the visual system is compact, reduces the stray light interference at the third spacing element, and improves the imaging quality of the visual system; at the same time, the size of the lens barrel is controlled to ensure good stability of the lens barrel during testing, and can ensure that the axial spacing from the second side of the first spacing element to the first side of the third spacing element is within a reasonable range, avoiding the situation of poor assembly stability caused by excessive assembly drop, and ensuring the stable assembly of each structure in the lens barrel.

[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 this 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 described as an example in the embodiment, the visual system is not limited to including four lenses. If necessary, the visual system can also include other numbers of lenses.

[0076] Figure 1 A schematic diagram of the dimensional markings of a visual system of this application is shown, Figure 1 in which parameters such as d1s, d1m, D1s, D1m, d3s, d3m, D3s, D3m, d0s, d0m, D0s, D0m, EP01, CP1, EP13, CP3, and L are marked to clearly and intuitively understand the meaning of these parameters. For the convenience of describing the surface shape of the visual system and specific lenses, these parameters will no longer be shown in the drawings when specific embodiments are described later.

[0077] The following further describes, with reference to the drawings, examples of the specific surface shape and parameters of the visual system applicable to the above embodiments.

[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; in Example 3, there are three examples: Example 3-1, Example 3-2, and Example 3-3. And the parameters of the optical system in the visual systems under the three examples in the same embodiment are the same. Specifically, the parameters such as the radius of curvature and central thickness of the first to fourth lenses of the visual system, as well as the spacing distance and higher-order term coefficients between the lenses, are the same, but 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 of the following Examples 1 to 3 is applicable to all embodiments of this application.

[0080] Example 1

[0081] As Figures 2 to 5 shown, the visual system of Example 1 is described. Figure 2 A schematic structural diagram of the visual system of Example 1-1 is shown, Figure 3 A schematic structural diagram of the visual system of Example 1-2 is shown, Figure 4 A schematic structural diagram of the visual system of Example 1-3 is shown.

[0082] As Figures 2 to 4As shown, the visual system includes a lens barrel P0 and a first lens E1, a first spacer P1, a second lens E2, a third lens E3, a third spacer P3, and a fourth lens E4 that are sequentially arranged in the lens barrel P0 along the optical axis from the first side to the second side. The second lens E2 and the third lens E3 are cemented to form a cemented lens.

[0083] In this embodiment, a polarizer LP, a reflective polarizing element RP, and a 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. A reflective element BS is arranged on the first side surface of the fourth lens.

[0084] In this embodiment, the light rays emitted from the image plane IMG sequentially pass through the fourth lens E4, the third lens E3, the second lens E2, and the quarter-wave plate QWP, and then are incident on the reflective polarizing element RP. After being reflected by the reflective polarizing element RP, the light rays are transmitted toward the display side, and then sequentially pass through the quarter-wave plate QWP, the second lens E2, and the third lens E3, and are incident on the reflective element BS. After being reflected by the reflective element BS, the light rays are transmitted toward the human eye side, and then sequentially pass through the third lens E3, the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, the polarizer LP, and the first lens E1, and are incident on the human eye for imaging.

[0085] As Figure 2 shown, it is a schematic structural diagram of the visual system of Embodiment 1-1. In this example, the first side surface and the second side surface of the first spacer P1 are respectively in contact with 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 spacer P3 are respectively in contact with the second side surface of the third lens and the first side surface of the fourth lens.

[0086] As Figure 3 shown, it is a schematic structural diagram of the visual system of Embodiment 1-2. In this example, the contact and abutment methods of each spacer are the same as those in Embodiment 1-1, and reference can be made to the relevant descriptions in Embodiment 1-1, which will not be elaborated here.

[0087] As Figure 4 shown, it is a schematic structural diagram of the visual system of Embodiment 1-3. In this example, the contact and abutment methods of each spacer are the same as those in Embodiment 1-1, and reference can be made to the relevant descriptions in Embodiment 1-1, which will not be elaborated here.

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

[0089] Table 2

[0090]

[0091]

[0092] In the first embodiment, the first side of the first lens is concave, and the second side of the first lens is convex. The first side of the second lens is concave, and the second side of the second lens is convex. The first side of the third lens is concave, and the second side of the third lens is convex. The first side of the fourth lens is concave, and the second side of the fourth lens is convex.

[0093] In the first embodiment, 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, and the on-axis distance TD from the first side of the first lens to the second side of the fourth lens is 16.86 mm.

[0094] Table 3 shows the basic structural parameter table of the visual system in the first embodiment, where the units of the radius of curvature and the thickness / distance are both millimeters (mm).

[0095] Table 3

[0096]

[0097]

[0098] In the first embodiment, the first side and the second side of the first lens E1 to the fourth lens E4 are both aspherical surfaces, and the surface profiles of the aspherical lenses can be defined by, but not limited to, the following aspherical formula:

[0099]

[0100] where x is the sagitta, the distance from the vertex of the aspherical surface to the position along the optical axis at a height of h; c is the paraxial curvature of the aspherical surface, c = 1 / R, that is, 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 of the i-th order of the aspherical surface. Table 4 below gives the high-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 for each aspherical surface 2 - 24 in the first embodiment.

[0101] Table 4

[0102] Coefficient / Surface 2 3 19 20 A4 -1.9635E-05 -1.1145E-05 -4.8028E-06 -1.7871E-05 A6 2.8520E-08 1.1583E-08 2.4759E-09 9.3402E-09 A8 -3.5163E-11 6.6992E-12 -2.9697E-12 5.9291E-12 A10 8.6685E-15 0.0000E+00 0.0000E+00 -1.1617E-14 A12 1.8834E-17 0.0000E+00 0.0000E+00 0.0000E+00 A14 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A16 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A18 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A20 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 Coefficient / Surface 21 22 23 24 A4 -1.7871E-05 -5.2874E-06 -1.0921E-05 7.8343E-06 A6 9.3402E-09 -7.0810E-09 5.4363E-09 1.2832E-09 A8 5.9291E-12 9.4381E-12 -7.8718E-12 -9.9082E-12 A10 -1.1617E-14 -8.5038E-15 2.5248E-15 -1.0041E-15 A12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A14 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A16 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A18 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A20 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0103] Figure 5 The MTF curve graph of the visual system of Embodiment 1 is shown. It can be seen from the figure that the optical function modulation value at a spatial frequency of 30 line pairs / mm reaches above 0.70, and the MTF curve is relatively high, indicating that the imaging quality at this spatial frequency is good.

[0104] Embodiment 2

[0105] As Figures 6 to 9 shown, the visual system of Embodiment 2 is described. Figure 6 The structural schematic diagram of the visual system of Embodiment 2-1 is shown, Figure 7 The structural schematic diagram of the visual system of Embodiment 2-2 is shown, Figure 8 The structural schematic diagram of the visual system of Embodiment 2-3 is shown.

[0106] As Figures 6 to 8 shown, the visual system includes a lens barrel P0 and 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 that are sequentially arranged in the lens barrel P0 along the optical axis from the first side to the second side. The second lens E2 and the third lens E3 are cemented to form a cemented lens.

[0107] In this embodiment, a polarizer LP, a reflective polarizing element RP, and a quarter-wave plate QWP are sequentially arranged on the second side surface of the first lens along the direction away from the first lens E1. A reflective element BS is arranged on the first side surface of the fourth lens.

[0108] In this embodiment, the light rays emitted from the image plane IMG sequentially pass through the fourth lens E4, the third lens E3, the second lens E2, and the transmission of the quarter-wave plate QWP, and then are incident on the reflective polarizing element RP. After being reflected by the reflective polarizing element RP, they are transmitted toward the display side, and then sequentially pass through the quarter-wave plate QWP, the second lens E2, and the transmission of the third lens E3, and then are incident on the reflective element BS. After being reflected by the reflective element BS, they are transmitted toward the human eye side, and then sequentially pass through the third lens E3, the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, the polarizer LP, and the transmission of the first lens E1, and then are incident on the human eye for imaging.

[0109] As Figure 6 shown, it is the structural schematic diagram of the visual system of Embodiment 2-1. In this example, the first side surface and the second side surface of the first spacer element P1 are respectively in contact with 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 spacer element P3 are respectively in contact with the second side surface of the third lens and the first side surface of the fourth lens.

[0110] As Figure 7As shown, it is a schematic structural diagram of the visual system of Example 2-2. In this example, the bearing and abutting manner of each spacer element is the same as that of Example 2-1. For the relevant description, reference can be made to Example 2-1, and it will not be elaborated here.

[0111] As Figure 8 shown, it is a schematic structural diagram of the visual system of Example 2-3. In this example, the bearing and abutting manner of each spacer element is the same as that of Example 2-1. For the relevant description, reference can be made to Example 2-1, and it will not be elaborated here.

[0112] In summary, the structural parameters of the visual system in Example 2 under Examples 2-1, 2-2, and 2-3 are shown in Table 5 (unit: mm).

[0113] Table 5

[0114]

[0115]

[0116] In Example 2, the first side of the first lens is concave, and the second side of the first lens is convex. The first side of the second lens is concave, and the second side of the second lens is convex. The first side of the third lens is concave, and the second side of the third lens is convex. The first side of the fourth lens is concave, and the second side of the fourth lens is convex.

[0117] In Example 2, the effective focal length f of the visual system is 29.14 mm, the effective focal length f1 of the first lens is 187.71 mm, the effective focal length f2 of the second lens is -2373.39 mm, the effective focal length f3 of the third lens is -621.25 mm, the effective focal length f4 of the fourth lens is 280.59 mm, the combined focal length f23 of the second lens and the third lens is -485.06 mm, the combined focal length fz of the first lens, the polarizer, the reflective polarizing element, and the quarter-wave plate is 187.13 mm, and the axial distance TD from the first side of the first lens to the second side of the fourth lens is 17.16 mm.

[0118] Table 6 shows the basic structural parameter table of the visual system in Example 2, where the unit of the radius of curvature and the thickness / distance is millimeter (mm).

[0119] Table 6

[0120]

[0121] The following Table 7 gives the higher-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 of the aspheres that can be used in Example 2.

[0122] Table 7

[0123] Coefficient / Surface 2 3 19 20 A4 -1.9635E-05 -1.1145E-05 -4.8028E-06 -1.7871E-05 A6 2.8520E-08 1.1583E-08 2.4759E-09 9.3402E-09 A8 -3.5163E-11 6.6992E-12 -2.9697E-12 5.9291E-12 A10 8.6685E-15 0.0000E+00 0.0000E+00 -1.1617E-14 A12 1.8834E-17 0.0000E+00 0.0000E+00 0.0000E+00 A14 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A16 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A18 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A20 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 Coefficient / Surface 21 22 23 24 A4 -1.7871E-05 -5.2874E-06 -1.0921E-05 1.2102E-05 A6 9.3402E-09 -7.0810E-09 5.4363E-09 -3.2166E-10 A8 5.9291E-12 9.4381E-12 -7.8718E-12 -2.4385E-12 A10 -1.1617E-14 -8.5038E-15 2.5248E-15 -2.6416E-15 A12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A14 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A16 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A18 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 A20 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

[0124] Figure 9 The MTF curve graph of the visual system of the second embodiment is shown. As can be seen from the figure, the optical function modulation value at a spatial frequency of 30 line pairs / mm reaches above 0.70, and the MTF curve is relatively high, indicating good imaging quality at this spatial frequency.

[0125] Embodiment 3

[0126] As Figures 10 to 13 shown, the visual system of the third embodiment is described. Figure 10 The structural schematic diagram of the visual system of Embodiment 3-1 is shown, Figure 11 The structural schematic diagram of the visual system of Embodiment 3-2 is shown, Figure 12 The structural schematic diagram of the visual system of Embodiment 3-3 is shown.

[0127] As Figures 10 to 12 shown, the visual system includes a lens barrel P0 and 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 that are sequentially arranged in the lens barrel P0 along the optical axis from the first side to the second side. The second lens E2 and the third lens E3 are cemented to form a cemented lens.

[0128] In this embodiment, a polarizer LP, a reflective polarizing element RP, and a quarter-wave plate QWP are sequentially arranged on the second side surface of the first lens along the direction away from the first lens E1. A reflective element BS is arranged on the first side surface of the fourth lens.

[0129] In this embodiment, the light rays emitted from the image plane IMG sequentially pass through the fourth lens E4, the third lens E3, the second lens E2, and are transmitted through the quarter-wave plate QWP, then are incident on the reflective polarizing element RP. After being reflected by the reflective polarizing element RP, they are transmitted toward the display side, and then sequentially pass through the quarter-wave plate QWP, the second lens E2, and the third lens E3 and are transmitted, and then are incident on the reflective element BS. After being reflected by the reflective element BS, they are transmitted toward the human eye side, and then sequentially pass through the third lens E3, the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, the polarizer LP, and the first lens E1 and are transmitted, and then are incident on the human eye for imaging.

[0130] As Figure 10As shown, it is a schematic structural diagram of the visual system of Example 3-1. In this example, the first side and the second side of the first spacer element P1 are respectively in contact with the second side of the first lens and the first side of the second lens. The first side and the second side of the third spacer element P3 are respectively in contact with the second side of the third lens and the first side of the fourth lens.

[0131] As Figure 11 shown, it is a schematic structural diagram of the visual system of Example 3-2. In this example, the contact and abutment methods of each spacer element are the same as those in Example 3-1. For relevant descriptions, reference can be made to Example 3-1, and details will not be elaborated here.

[0132] As Figure 12 shown, it is a schematic structural diagram of the visual system of Example 3-3. In this example, the contact and abutment methods of each spacer element are the same as those in Example 3-1. For relevant descriptions, reference can be made to Example 3-1, and details will not be elaborated here.

[0133] In summary, the structural parameters of the visual system in Example 3 under Examples 3-1, 3-2, and 3-3 are as shown in Table 8 (unit: mm).

[0134] Table 8

[0135] Parameter / Example 3-1 3-2 3-3 d1s 40.940 40.549 40.350 d1m 40.940 40.549 40.350 D1s 51.102 53.000 52.640 D1m 51.102 53.000 52.640 d3s 50.007 50.148 50.324 d3m 50.007 50.148 50.324 D3s 54.800 54.800 55.053 D3m 54.800 54.800 55.053 d0s 40.481 39.606 42.486 d0m 56.822 57.550 56.486 D0s 58.788 57.503 55.411 D0m 61.000 61.780 60.324 EP01 4.225 5.090 5.561 CP1 0.050 0.050 0.050 EP13 5.647 5.647 5.825 CP3 0.050 0.050 0.050 L 20.600 22.663 23.041

[0136] In Example 3, the first side of the first lens is concave, and the second side of the first lens is convex. The first side of the second lens is concave, and the second side of the second lens is convex. The first side of the third lens is concave, and the second side of the third lens is convex. The first side of the fourth lens is concave, and the second side of the fourth lens is convex.

[0137] In Example 3, the effective focal length f of the visual system is 29.65 mm, the effective focal length f1 of the first lens is 204.66 mm, the effective focal length f2 of the second lens is -522.59 mm, the effective focal length f3 of the third lens is -2570.24 mm, the effective focal length f4 of the fourth lens is 319.39 mm, the combined focal length f23 of the second lens and the third lens is -438.78 mm, the combined focal length fz of the first lens, the polarizer, the reflective polarizing element, and the quarter-wave plate is 203.91 mm, and the axial distance TD from the first side of the first lens to the second side of the fourth lens is 17.20 mm.

[0138] Table 9 shows the basic structural parameter table of the visual system in Example 3, where the unit of the radius of curvature and the thickness / distance is millimeter (mm).

[0139] Table 9

[0140]

[0141] Table 10 below gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 for each aspheric surface in Example 3.

[0142] Table 10

[0143]

[0144]

[0145] Figure 13 The MTF curve graph of the visual system in Example 3 is shown. As can be seen from the figure, the optical function modulation value at a spatial frequency of 30 line pairs / mm reaches above 0.70, and the MTF curve is relatively high, indicating good imaging quality at this spatial frequency.

[0146] In summary, Examples 1 to 3 respectively satisfy the relationships shown in Table 11.

[0147] Table 11

[0148] Conditional formula / Example 1-1 1-2 1-3 2-1 2-2 2-3 3-1 3-2 3-3 f23 / d3s -9.75 -9.74 -9.72 -9.70 -9.70 -9.67 -8.77 -8.75 -8.72 f / (CP1 + EP13) 5.18 5.10 5.01 5.23 5.38 5.27 5.20 5.20 5.05 f1 / (d1s + d1m) 2.32 2.31 2.33 2.31 2.30 2.31 2.50 2.52 2.54 fz / d0s 4.69 4.59 4.83 4.56 4.66 4.49 5.04 5.15 4.80 R2 / EP01 -8.35 -7.32 -8.35 -8.71 -8.71 -7.38 -8.25 -6.85 -6.27 (D1m - d1m) / CT2 5.08 4.99 5.18 4.50 4.51 4.53 5.08 6.23 6.15 (D3m - d3m) / T34 1.56 1.54 1.50 1.10 1.09 1.21 1.49 1.44 1.47 D3s / R6 -1.37 -1.37 -1.37 -1.33 -1.33 -1.34 -1.37 -1.37 -1.37 CP3×(f3 / f4)(mm) -0.20 -0.20 -0.20 -0.17 -0.11 -0.11 -0.40 -0.40 -0.40 d0m / CT4 18.73 18.94 18.59 18.90 19.06 18.55 18.94 19.18 18.83 (D0m - d0s) / EP13 3.57 3.47 3.58 3.60 3.86 3.64 3.63 3.93 3.06 (R1 + R8) / L -4.27 -4.14 -4.12 -4.10 -4.27 -3.99 -3.92 -3.56 -3.50 (D1s + D3s) / TD 6.21 6.21 6.21 6.00 6.02 6.04 6.16 6.27 6.26 D0s / f 1.97 1.93 1.76 1.72 1.78 1.69 1.98 1.94 1.87 d1s / CT1 12.61 12.66 12.59 11.71 11.78 11.73 12.31 12.20 12.14 L / (CT2 + CT3) 4.98 5.13 5.17 5.11 4.91 5.26 5.09 5.60 5.69

[0149] Table 12 shows parameters such as the effective focal length of the visual systems in Examples 1 to 3 and the effective focal lengths of each lens.

[0150] Table 12

[0151] Parameter / Example 1-1 1-2 1-3 2-1 2-2 2-3 3-1 3-2 3-3 f(mm) 29.59 29.59 29.59 29.14 29.14 29.14 29.65 29.65 29.65 f1(mm) 187.43 187.43 187.43 187.71 187.71 187.71 204.66 204.66 204.66 f2(mm) -677.74 -677.74 -677.74 -2373.39 -2373.39 -2373.39 -522.59 -522.59 -522.59 f3(mm) -1634.18 -1634.18 -1634.18 -621.25 -621.25 -621.25 -2570.24 -2570.24 -2570.24 f4(mm) 408.25 408.25 408.25 280.59 280.59 280.59 319.39 319.39 319.39 f23(mm) -481.87 -481.87 -481.87 -485.06 -485.06 -485.06 -438.78 -438.78 -438.78 fz(mm) 186.84 186.84 186.84 187.13 187.13 187.13 203.91 203.91 203.91 TD(mm) 16.86 16.86 16.86 17.16 17.16 17.16 17.20 17.20 17.20

[0152] This application also provides an imaging device, whose electronic photosensitive element can be a charge-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 on a mobile electronic device such as a mobile phone. The imaging device is equipped with the visual system described above.

[0153] Optionally, the imaging device can be a VR device or an AR device.

[0154] Obviously, the above-described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0155] 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 forms are also intended to include the plural forms. In addition, it should also be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0156] It should be noted that the terms "first", "second", etc. in the specification, claims and drawings of the present application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0157] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within 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 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 is glued to the third lens to form a glued lens; The polarizer, the reflective polarizing element and the quarter wave plate are sequentially arranged on the second side surface of the first lens 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 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; Among them, the combined focal length f23 of the second lens and the third lens and the inner diameter d3s of the first side of the third spacing element satisfy: -9.75≤f23 / d3s≤-8.72; the effective focal length f of the visual system, the maximum axial thickness CP1 of the first spacing element and the axial interval EP13 from the second side of the first spacing element to the first side of the third spacing element satisfy: 5.00<f / (CP1+EP13)<5.

40.

2. The visual system according to claim 1, characterized in that: The effective focal length f1 of the first lens, the inner diameter d1s of the first side surface of the first spacing element, and the inner diameter d1m of the second side surface of the first spacing element satisfy: 2.30≤f1 / (d1s+d1m)≤2.

54.

3. The visual system according to claim 1, characterized in that: The combined focal length fz of the first lens, the polarizer, the reflective polarizing element and the quarter-wave plate and the inner diameter d0s of the first side surface of the lens barrel satisfy the following relationship: 4.49≤fz / d0s≤5.

15.

4. The visual system according to claim 1, characterized in that: The curvature radius R2 of the second side surface of the first lens and the on-axis interval EP01 from the first side surface of the lens barrel to the first side surface of the first spacing element satisfy: -8.71≤R2 / EP01≤-6.

27.

5. The visual system according to claim 1, characterized in that: An outer diameter D1m of the second side surface of the first spacer element, an inner diameter d1m of the second side surface of the first spacer element, and a center thickness CT2 of the second lens on the optical axis of the visual system satisfy: 4.50≤(D1m-d1m) / CT2≤6.

23.

6. The visual system according to claim 1, characterized in that: An outer diameter D3m of the second side surface of the third spacing element, an inner diameter d3m of the second side surface of the third spacing element, and an axial distance T34 from the second side surface of the third lens to the first side surface of the fourth lens satisfy: 1.09≤(D3m-d3m) / T34≤1.

56.

7. The visual system according to claim 1, characterized in that: The maximum axial thickness CP3 of the third spacing element, the effective focal length f3 of the third lens and the effective focal length f4 of the fourth lens satisfy the following: -0.40 mm ≤ CP3 × (f3 / f4) ≤ -0.11 mm.

8. 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 center thickness CT4 of the fourth lens on the optical axis of the visual system satisfy the following: 18.55≤d0m / CT4≤19.

18.

9. The visual system according to claim 1, characterized in that: The outer diameter D0m of the second side of the lens barrel, the inner diameter d0s of the first side of the lens barrel, and the axial interval EP13 from the second side of the first spacing element to the first side of the third spacing element satisfy: 3.06≤(D0m-d0s) / EP13≤3.

93.

10. The visual system according to claim 1, characterized in that: The curvature radius R1 of the first side surface of the first lens, the curvature radius R8 of the second side surface of the fourth lens, and the axial distance L from the first side surface of the lens barrel to the second side surface of the lens barrel satisfy: -4.27≤(R1+R8) / L≤-3.

50.

11. The visual system according to claim 1, characterized in that: An outer diameter D1s of the first side surface of the first spacing element, an outer diameter D3s of the first side surface of the third spacing element, and an axial distance TD from the first side surface of the first lens to the second side surface of the fourth lens satisfy: 6.00≤(D1s+D3s) / TD≤6.

27.

12. The visual system according to claim 1, characterized in that: An outer diameter D0s of the first side surface of the lens barrel and an effective focal length f of the visual system satisfy the following relationship: 1.69≤D0s / f≤1.

98.

13. The visual system according to any one of claims 1 to 12, characterized in that: An inner diameter d1s of the first side surface of the first spacing element and a center thickness CT1 of the first lens on the optical axis of the visual system satisfy the following: 11.71≤d1s / CT1≤12.

66.

14. The visual system according to any one of claims 1 to 12, characterized in that: The axial distance L from the first side surface of the lens barrel to the second side surface of the lens barrel, 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: 4.91≤L / (CT2+CT3)≤5.69.

Images