Visual system

Abstract

The application provides a visual system. The visual system comprises a lens barrel, 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 and a quarter-wave plate, and satisfies: 3.94<=fz / d1s<=4.51; and satisfies: 0.98<=EP13 / (CT2+CT3)<=1.45. The application solves the problem that the four-lens visual system in the prior art needs to arrange a cemented lens and a reflective element to meet the requirement of compact structure, thereby increasing the deformation amount of the lens group assembly and causing the assembly stability to be poor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical imaging devices, in particular to a visual system. BACKGROUND

[0002] With the continuous development of optical technology, visual systems have been widely used in many fields, such as virtual reality, augmented reality, microscopes, telescopes, etc. Among them, the four-piece visual system has become one of the more common designs due to its fewer lens pieces, simple structure, lower cost, etc.

[0003] However, in the process of pursuing compact structure, the four-piece visual system in the prior art usually needs to set a cemented lens and a reflective element, but such design also brings some problems in actual application, for example, the cemented lens is easily affected by stress and temperature changes during assembly, which increases the deformation of the lens assembly and reduces the assembly stability of the lens, and further causes the field curvature of the lens surface to change, affecting the imaging quality.

[0004] That is, the four-piece visual system in the prior art has the problem of setting a cemented lens and a reflective element to meet the requirement of compact structure, which further causes the deformation of the lens assembly to increase and the assembly stability to deteriorate. SUMMARY

[0005] The main purpose of the present application is to provide a visual system to solve the problem of the four-piece visual system in the prior art, which sets a cemented lens and a reflective element to meet the requirement of compact structure, which further causes the deformation of the lens assembly to increase and the assembly stability to deteriorate.

[0006] In order to achieve the above object, according to one aspect of the present application, there is provided a visual system, comprising a lens barrel and a lens group and a spacer element group arranged in the lens barrel, the lens group being composed of four lenses, a polarizer, a reflective polarizing element and a quarter-wave plate, the four lenses being, in order from a first side to a second side, a first lens having positive refractive power, a second lens having negative refractive power, a third lens having negative refractive power and a fourth lens having positive or negative refractive power, the first side of the first lens being concave and the second side being convex, the first side of the second lens being concave and the second side being convex, the first side of the third lens being concave and the second side being convex, and the first side of the fourth lens being concave and the second side being convex, the second lens and the third lens being cemented to form a cemented lens, the polarizer, the reflective polarizing element and the quarter-wave plate being arranged in order on the first side of the first lens in a direction close to the first lens, the spacer element group comprising 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, the combination focal length fz of the polarizer, the reflective polarizing element, the quarter-wave plate and the first lens and the inner diameter d1s of the first side of the first spacer element satisfying: 3.94≤fz / d1s≤4.51, and the interval distance EP13 on the optical axis of the visual system from the second side of the first spacer element to the first side of the third spacer element, the central thickness CT2 of the second lens on the optical axis and the central thickness CT3 of the third lens on the optical axis satisfying: 0.98≤EP13 / (CT2+CT3)≤1.45.

[0007] According to another aspect of the present application, there is provided an optical system comprising a lens barrel and a lens group and a spacer group arranged in the lens barrel, the lens group consisting of four lenses, a polarizer, a reflective polarizing element and a quarter-wave plate, the four lenses being, in order from a first side to a second side, a first lens having positive refractive power, a second lens having negative refractive power, a third lens having negative refractive power, and a fourth lens having positive refractive power or negative refractive power, the first side of the first lens being concave and the second side being convex; the first side of the second lens being concave and the second side being convex; the first side of the third lens being concave and the second side being convex; the first side of the fourth lens being concave and the second side being convex; the second lens and the third lens being cemented to form a cemented lens; the polarizer, the reflective polarizing element and the quarter-wave plate being arranged in order on the first side of the first lens in a direction close to the first lens; the spacer group comprising 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; the combination focal length fz of the polarizer, the reflective polarizing element, the quarter-wave plate and the first lens and the inner diameter d1s of the first side of the first spacer element satisfying: 3.94≤fz / d1s≤4.51; the interval distance EP13 on the optical axis from the second side of the first spacer element to the first side of the third spacer element, the radius of curvature R3 of the first side of the second lens and the radius of curvature R6 of the second side of the third lens satisfying: 2.22mm≤EP13×(R3 / R6)≤4.20mm.

[0008] Further, the interval distance EP01 on the optical axis from the first side of the lens barrel to the first side of the first spacer element, the central thickness CTL of the polarizer on the optical axis, the central thickness CTR of the reflective polarizing element on the optical axis and the central thickness CTQ of the quarter-wave plate on the optical axis satisfying: 24.03≤EP01 / (CTL+CTR+CTQ)≤36.94.

[0009] Further, the radius of curvature R1 of the first side of the first lens and the inner diameter d0s of the first side of the lens barrel satisfying: -1.34≤R1 / d0s≤-0.97.

[0010] Further, the inner diameter d1m of the second side of the first spacer element and the radius of curvature R2 of the second side of the first lens satisfying: -1.59≤d1m / R2≤-1.19.

[0011] Further, the combination focal length f23 of the second lens and the third lens, the outer diameter D1s of the first side of the first spacer element and the outer diameter D3s of the first side of the third spacer element satisfying: -2.42≤f23 / (D1s+D3s)≤-1.50.

[0012] Further, a distance EP13 on the optical axis between the second side surface of the first spacer element and the first side surface of the third spacer element, a curvature radius R3 of the first side surface of the second lens, and a curvature radius R6 of the second side surface of the third lens satisfy: 2.22 mm ≤ EP13 x (R3 / R6) ≤ 4.20 mm.

[0013] Further, an effective focal length f1 of the first lens and an outer diameter D1m of the second side surface of the first spacer element satisfy: 2.98 ≤ f1 / D1m ≤ 3.49.

[0014] Further, an effective focal length f of the visual system and an on-axis distance L from the first side surface of the barrel to the second side surface of the barrel satisfy: 1.28 ≤ f / L ≤ 1.66.

[0015] Further, an on-axis distance TD from the first side surface of the first lens to the second side surface of the fourth lens, a maximum axial thickness CP1 of the first spacer element, a distance EP13 on the optical axis between the second side surface of the first spacer element and the first side surface of the third spacer element, and a maximum axial thickness CP3 of the third spacer element satisfy: 1.60 ≤ TD / (CP1+EP13+CP3) ≤ 2.66.

[0016] Further, an outer diameter D0m of the second side surface of the barrel, an inner diameter d0m of the second side surface of the barrel, and a central thickness CT4 of the fourth lens on the optical axis satisfy: 0.70 ≤ (D0m-d0m) / CT4 ≤ 2.47.

[0017] Further, an effective focal length f3 of the third lens, an inner diameter d3s of the first side surface of the third spacer element, and an inner diameter d3m of the second side surface of the third spacer element satisfy: -3.98 ≤ f3 / (d3s+d3m) ≤ -2.26.

[0018] Further, a curvature radius R7 of the first side surface of the fourth lens, a curvature radius R8 of the second side surface of the fourth lens, and an outer diameter D3m of the second side surface of the third spacer element satisfy: -2.01 ≤ (R7+R8) / D3m ≤ -1.22.

[0019] Further, an outer diameter D0s of the first side surface of the barrel and an on-axis distance TD from the first side surface of the first lens to the second side surface of the fourth lens satisfy: 3.22 ≤ D0s / TD ≤ 4.07.

[0020] Further, an inner diameter d0s of the first side surface of the barrel and a central thickness CT1 of the first lens on the optical axis satisfy: 13.56 ≤ d0s / CT1 ≤ 15.04.

[0021] Further, the effective focal length f of the visual system, the outer diameter D0m of the second side of the lens barrel and the outer diameter D0s of the first side of the lens barrel satisfy: 2.80≤f / (D0m-D0s)≤5.43.

[0022] Further, the visual system further comprises a reflecting element, which is located between the third lens and the image plane of the visual system.

[0023] By applying the technical scheme of the present application, the visual system of the present application is composed of a lens barrel and four lenses, a polarizer, a reflecting polarizing element, a quarter-wave plate and two spacer elements arranged in the lens barrel, the axial length of the visual system is compressed by reasonably setting the focal power and surface shape of the four lenses, the positions of the polarizer, the reflecting polarizing element, the quarter-wave plate and the two spacer elements, and by gluing the second lens and the third lens to form a glued lens, and the structure design is compact by setting the reflecting polarizing element to change the direction of light path transmission and realize the folding of the light path, and further compress the axial length of the visual system. However, in this case, the glued lens is easily affected by stress and temperature change during assembly, which increases the deformation amount of the lens assembly and reduces the assembly stability of the lens. Therefore, by limiting 3.94≤fz / d1s≤4.51 and 0.98≤EP13 / (CT2+CT3)≤1.45, the central thickness of the second lens and the third lens is reasonably distributed, the shape of the second lens and the third lens is optimized, the shape rationality is ensured, the processability of the second lens and the third lens is ensured, the deformation amount of the second lens and the third lens during assembly is reduced, the field curvature is optimized, the assembly stability is improved, and the imaging quality is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0024] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the present application, and together with the description of the present application, serve to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0025] Figure 1 A size annotation diagram of the visual system of an optional embodiment of the present application is shown;

[0026] Figure 2 A structure schematic diagram of the visual system of embodiment 1-1 of the present application is shown;

[0027] Figure 3 A structure schematic diagram of the visual system of embodiment 1-2 of the present application is shown;

[0028] Figure 4 A structure schematic diagram of the visual system of embodiment 1-3 of the present application is shown;

[0029] Figure 5A MTF graph of the visual system of Embodiment One of the present application is shown.

[0030] Figure 6 A structural schematic diagram of the visual system of Embodiment 2-1 of the present application is shown.

[0031] Figure 7 A structural schematic diagram of the visual system of Embodiment 2-2 of the present application is shown.

[0032] Figure 8 A structural schematic diagram of the visual system of Embodiment 2-3 of the present application is shown.

[0033] Figure 9 A MTF graph of the visual system of Embodiment Two of the present application is shown.

[0034] Figure 10 A structural schematic diagram of the visual system of Embodiment 3-1 of the present application is shown.

[0035] Figure 11 A structural schematic diagram of the visual system of Embodiment 3-2 of the present application is shown.

[0036] Figure 12 A structural schematic diagram of the visual system of Embodiment 3-3 of the present application is shown.

[0037] Figure 13 A MTF graph of the visual system of Embodiment Three of the present application is shown.

[0038] Wherein, the above-mentioned drawings include the following reference signs:

[0039] 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, reflecting element; IMG, image plane. DETAILED DESCRIPTION

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

[0041] It should be noted that, unless otherwise specified, all the technical and scientific terms used in the present application have the same meaning as that generally understood by the ordinary skilled in the art to which the present application belongs.

[0042] In the present application, the orientation words such as "upper", "lower", "top", "bottom" used herein are generally directed to the directions shown in the drawings or the vertical, perpendicular or gravity directions of the components themselves, unless otherwise specified. Similarly, for the convenience of understanding and description, "inner" and "outer" refer to the inner and outer relative to the contour of the components themselves, but the orientation words are not used to limit the present application.

[0043] In the drawings, the thickness, size and shape of the lens have been slightly exaggerated for the convenience of explanation. Specifically, the shape of the spherical or aspherical surface shown in the drawings is shown by way of example. That is, the shape of the spherical or aspherical surface is not limited to the shape of the spherical or aspherical surface shown in the drawings. The drawings are merely examples and are not strictly drawn to scale.

[0044] In this context, 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 skilled in the art, with the R value (R refers to the radius of curvature in the paraxial region, usually refers to the R value on the lens data in the optical software) to judge the convexity and concavity. With respect to the first side, when the R value is positive, it is determined to be convex, and when the R value is negative, it is determined to be concave; with respect to the second side, when the R value is positive, it is determined to be concave, and when the R value is negative, it is determined to be convex. When the R value is infinite, it is determined to be 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.

[0045] In order to solve the problem that the four-piece visual system in the prior art sets a cemented lens and a reflecting element to meet the requirement of compact structure, thereby increasing the deformation amount of the lens group and causing poor stability of the group, the present application provides a visual system.

[0046] As Figures 1 to 13In an optional embodiment of the present application, the visual system 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 and a quarter-wave plate, the four lenses are in order from the first side to the second side a first lens with positive refractive power, a second lens with negative refractive power, a third lens with negative refractive power and a fourth lens with positive or negative refractive 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 arranged in order on the first side of the first lens in the direction close to the first 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; the combination focal length fz of the polarizer, the reflective polarizing element, the quarter-wave plate and the first lens and the inner diameter d1s of the first side of the first spacer element satisfy: 3.94≤fz / d1s≤4.51; the interval distance EP13 of the second side of the first spacer element to the first side of the third spacer element on the optical axis of the visual system, the central thickness CT2 of the second lens on the optical axis and the central thickness CT3 of the third lens on the optical axis satisfy: 0.98≤EP13 / (CT2+CT3)≤1.45.

[0047] The visual system of the present application is composed of a lens barrel and four lenses, a polarizer, a reflective polarizing element, a quarter-wave plate and two spacer elements arranged in the lens barrel. By reasonably setting the refractive power and surface shape of the four lenses, the positions of the polarizer, the reflective polarizing element, the quarter-wave plate and the two spacer elements, and cementing the second lens and the third lens to form a cemented lens, the axial length of the visual system is compressed. At the same time, the reflective polarizing element is arranged to change the direction of light path transmission, realize the folding of the light path, and further compress the axial length of the visual system, which is conducive to realizing the compact structure design. However, in this case, the cemented lens during assembly is easily affected by stress and temperature changes, resulting in an increase in the deformation amount of the lens assembly, and the assembly stability of the lens becomes poor. Therefore, by constraining 3.94≤fz / d1s≤4.51 and 0.98≤EP13 / (CT2+CT3)≤1.45, the central thickness of the second lens and the third lens is reasonably distributed, the shape of the second lens and the third lens is optimized, the shape rationality is ensured, the processability of the second lens and the third lens is ensured, the deformation amount of the second lens and the third lens during assembly is reduced, the field curvature is optimized, the assembly stability is improved, and the imaging quality is ensured.

[0048] In addition, referring to Table 1 below, the face type field curvature offset amounts of the first side surface of the second lens and the second side surface of the third lens in each field of view are respectively shown in the table below when the visual system satisfies EP13 / (CT2+CT3) = 1.19, 1.70, 0.50 under the premise that the visual system satisfies 3.94≤fz / d1s≤4.51.

[0049] It can be seen from Table 1 that when the visual system satisfies EP13 / (CT2+CT3) = 1.19, the face type field curvature offset amounts of the first side surface of the second lens and the second side surface of the third lens in each field of view are smaller, the sensitivity is smaller, and the performance is better. When the visual system satisfies EP13 / (CT2+CT3) = 1.70, the face type field curvature offset amounts of the first side surface of the second lens and the second side surface of the third lens in each field of view are larger, the sensitivity is larger, and the performance is poorer. When the visual system satisfies EP13 / (CT2+CT3) = 0.50, the face type field curvature offset amounts of the first side surface of the second lens and the second side surface of the third lens in each field of view are larger, the sensitivity is larger, and the performance is poorer. It can be seen that when 3.94≤fz / d1s≤4.51 is satisfied and EP13 / (CT2+CT3) is controlled in the range of 0.98 to 1.45, the face type field curvature offset amounts of the first side surface of the second lens and the second side surface of the third lens in each field of view are the smallest, the sensitivity is the smallest, the deformation amount under the assembly stress is smaller, and the assembly stability is the best. Therefore, by restricting 3.94≤fz / d1s≤4.51 and 0.98≤EP13 / (CT2+CT3)≤1.45, the performance requirements and the compact structure are guaranteed, the center thickness of the second lens and the third lens is reasonably distributed, the shape of the second lens and the third lens is optimized, the shape rationality is guaranteed, the processability of the second lens and the third lens is guaranteed, the deformation amount of the second lens and the third lens during assembly is reduced, the field curvature is optimized, the assembly stability is improved, and the imaging quality is guaranteed.

[0050] Table 1

[0051]

[0052] In the embodiment, the interval distance EP01 on the optical axis between the first side surface of the lens barrel and the first side surface of the first spacer element, the central thickness CTL of the polarizer on the optical axis, the central thickness CTR of the reflective polarizing element on the optical axis, and the central thickness CTQ of the quarter-wave plate on the optical axis satisfy: 24.03≤EP01 / (CTL+CTR+CTQ)≤36.94. Through the above relationship, the central thicknesses of the polarizer, the reflective polarizing element, and the quarter-wave plate on the optical axis are favorably distributed, the processability of the polarizer, the reflective polarizing element, and the quarter-wave plate is ensured in the case of ensuring the compactness of the overall structure and the rationality of the thickness, so as to facilitate the integration of the polarizer, the reflective polarizing element, and the quarter-wave plate with the first lens.

[0053] In the embodiment, the radius of curvature R1 of the first side surface of the first lens and the inner diameter d0s of the first side surface of the lens barrel satisfy: -1.34≤R1 / d0s≤-0.97. Through the above relationship, the control of the light path trend is realized by limiting the radius of curvature of the first side surface of the first lens to be negative, and the inner diameter of the first side surface of the lens barrel is also controlled to ensure the etendue of the visual system.

[0054] In the embodiment, the inner diameter d1m of the second side surface of the first spacer element and the radius of curvature R2 of the second side surface of the first lens satisfy: -1.59≤d1m / R2≤-1.19. Through the above relationship, the control of the light path trend is realized by limiting the radius of curvature of the second side surface of the first lens to be negative, and the inner diameter of the second side surface of the first spacer element is also controlled to ensure that the first spacer element does not block the imaging light, and the etendue of the visual system is ensured.

[0055] In the embodiment, the combined focal length f23 of the second lens and the third lens, the outer diameter D1s of the first side surface of the first spacer element, and the outer diameter D3s of the first side surface of the third spacer element satisfy: -2.42≤f23 / (D1s+D3s)≤-1.50. Through the above relationship, the reasonable control of the light path trend is realized by limiting the combined focal length of the second lens and the third lens to be negative, and at the same time, sufficient bearing area is ensured between the second lens and the third lens, the first spacer element, and the third spacer element, to ensure the stability of the assembly.

[0056] In the embodiment, the interval distance EP13 of the second side surface of the first spacer element to the first side surface of the third spacer element on the optical axis, the radius of curvature R3 of the first side surface of the second lens, and the radius of curvature R6 of the second side surface of the third lens satisfy: 2.22mm≤EP13×(R3 / R6)≤4.20mm. Through the above relationship, the ratio of the radius of curvature of the first side surface of the second lens to the second side surface of the third lens is limited, so as to ensure that the performance of the visual system meets the requirements; at the same time, the interval size of the second side surface of the first spacer element to the first side surface of the third spacer element can be controlled, so as to indirectly control the edge thickness of the second lens and the third lens within a reasonable range, optimize the shape of the second lens and the third lens, ensure the shape rationality, ensure the processing feasibility of the second lens and the third lens, reduce the deformation amount during assembly, optimize the field curvature, improve the assembly stability, and further ensure the imaging quality.

[0057] In the embodiment, the effective focal length f1 of the first lens and the outer diameter D1m of the second side surface of the first spacer element satisfy: 2.98≤f1 / D1m≤3.49. Through the above relationship, the effective focal length of the first lens is limited to be positive to realize reasonable control of the light path trend, and at the same time the outer diameter of the second side surface of the first spacer element can be controlled to ensure that the shape and outer diameter of the first lens are not too large, and the processing feasibility of the first lens is ensured.

[0058] In the embodiment, the effective focal length f of the visual system and the axial distance L of the first side surface of the lens barrel to the second side surface of the lens barrel satisfy: 1.28≤f / L≤1.66. Through the above relationship, the effective focal length of the visual system is limited to realize reasonable control of the light path trend, and at the same time the total axial height of the lens barrel can be controlled, which is beneficial to ensure the miniaturization of the visual system and is beneficial to the molding of the lens barrel.

[0059] In the embodiment, the axial distance TD of the first side surface of the first lens to the second side surface of the fourth lens, the maximum axial thickness CP1 of the first spacer element, the interval distance EP13 of the second side surface of the first spacer element to the first side surface of the third spacer element on the optical axis, and the maximum axial thickness CP3 of the third spacer element satisfy: 1.60≤TD / (CP1+EP13+CP3)≤2.66. Through the above relationship, the axial distance of the first side surface of the first lens to the second side surface of the fourth lens is limited within a reasonable range, which can prevent the increase of the size of the visual system caused by the too large axial distance, and can prevent the thickness design of each lens from being limited caused by the too small axial distance, thereby affecting the processing feasibility of each lens.

[0060] In the embodiment, the outer diameter D0m of the second side surface of the lens barrel, the inner diameter d0m of the second side surface of the lens barrel, and the center thickness CT4 of the fourth lens on the optical axis satisfy: 0.70≤(D0m-d0m) / CT4≤2.47. Through the above relationship, the wall thickness of the second side end of the lens barrel is constrained, which can prevent the insufficient wall thickness of the lens barrel from affecting the structural strength, and can control the thickness of the fourth lens within a reasonable range, thereby ensuring the machining feasibility of the fourth lens and the lens barrel, and ensuring the stable abutment of the fourth lens and the lens barrel.

[0061] In the embodiment, the effective focal length f3 of the third lens, the inner diameter d3s of the first side surface of the third spacer element, and the inner diameter d3m of the second side surface of the third spacer element satisfy: -3.98≤f3 / (d3s+d3m)≤-2.26. Through the above relationship, the effective focal length of the third lens is limited to be negative, which can effectively control the light path and the reasonable control, and can also control the inner diameters of the first side surface and the second side surface of the third spacer element, thereby ensuring that the third spacer element does not block the imaging light path, and ensuring the light flux.

[0062] In the embodiment, the radius of curvature R7 of the first side surface of the fourth lens, the radius of curvature R8 of the second side surface of the fourth lens, and the outer diameter D3m of the second side surface of the third spacer element satisfy: -2.01≤(R7+R8) / D3m≤-1.22. Through the above relationship, the sum of the radii of curvature of the first side surface and the second side surface of the fourth lens is limited to be negative, which can effectively control the deflection of the light path, and can also control the outer diameter of the second side surface of the third spacer element, thereby ensuring the machinability of the third spacer element, and facilitating the stable abutment of the third spacer element and the fourth lens.

[0063] In the embodiment, the outer diameter D0s of the first side surface of the lens barrel and the on-axis distance TD from the first side surface of the first lens to the second side surface of the fourth lens satisfy: 3.22≤D0s / TD≤4.07. Through the above relationship, the outer diameter of the first side surface of the lens barrel is limited within a reasonable range, which can prevent the insufficient support area caused by the too small outer diameter from affecting the stability of lens assembly, and can prevent the too large inner diameter from causing the excessive size of the visual system, thereby ensuring the miniaturization, compactness, and assembly stability of the lens.

[0064] In the embodiment, the inner diameter d0s of the first side surface of the lens barrel and the center thickness CT1 of the first lens on the optical axis satisfy: 13.56≤d0s / CT1≤15.04. Through the above relationship, the inner diameter of the first side surface of the lens barrel is prevented from being too large to affect the stability of lens assembly, and the thickness of the first lens is controlled within a reasonable range, thereby ensuring the machining feasibility of the first lens, and ensuring the assembly reliability of the first lens and the lens barrel.

[0065] In the embodiment, the effective focal length f of the visual system, the outer diameter D0m of the second side of the lens barrel, and the outer diameter D0s of the first side of the lens barrel satisfy the relationship: 2.80≤f / (D0m-D0s)≤5.43. Through the above relationship, the light flux of the visual system and the size of the lens barrel are controlled within a reasonable range, which can ensure sufficient light flux and limit the size of the lens barrel, and is conducive to realizing small size.

[0066] In the embodiment, the visual system further includes a reflecting element located between the third lens and the image plane of the visual system. In an optional embodiment of the present application, the reflecting element can be arranged on the second side of the fourth lens, or on the first side of the fourth lens, or on the second side of the third lens. By reasonably arranging the position of the reflecting element, the reflection timing of the light is controlled, and the folding of the optical path is realized, which is conducive to reducing the total optical length and ensuring the miniaturization of the visual system.

[0067] In addition, in another optional embodiment of the present application, a visual system is provided, which includes a lens barrel and a lens group and a spacer group arranged in the lens barrel, the lens group is composed of four lenses, a polarizer, a reflecting polarizing element, and a quarter-wave plate, the four lenses are sequentially arranged from the first side to the second side as 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 or negative focal power, the first side of the first lens is a concave surface, and the second side is a convex surface; the first side of the second lens is a concave surface, and the second side is a convex surface; the first side of the third lens is a concave surface, and the second side is a convex surface; the first side of the fourth lens is a concave surface, and the second side is a convex surface; the second lens and the third lens are cemented to form a cemented lens; the polarizer, the reflecting polarizing element, and the quarter-wave plate are sequentially arranged on the first side of the first lens in a direction close to the first lens; the spacer 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; the combined focal length fz of the polarizer, the reflecting polarizing element, the quarter-wave plate, and the first lens satisfies the relationship: 3.94≤fz / d1s≤4.51, where d1s is the inner diameter of the first side of the first spacer element; the interval distance EP13 of the second side of the first spacer element to the first side of the third spacer element on the optical axis, the curvature radius R3 of the first side of the second lens, and the curvature radius R6 of the second side of the third lens satisfy the relationship: 2.22mm≤EP13×(R3 / R6)≤4.20mm.

[0068] The visual system of the present application is composed of a lens barrel and four lenses, a polarizer, a reflective polarizing element, a quarter-wave plate and two spacer elements arranged in the lens barrel. By reasonably arranging the focal power and surface shape of the four lenses, the positions of the polarizer, the reflective polarizing element, the quarter-wave plate and the two spacer elements, and gluing the second lens and the third lens to form a glued lens, the axial length of the visual system can be compressed. At the same time, the reflective polarizing element can change the direction of light transmission and realize the folding of the light path, further compressing the axial length of the visual system and facilitating the compact structure design. However, in this case, the glued lens during assembly is easily affected by stress and temperature changes, resulting in an increase in the deformation amount of the lens assembly and a decrease in the assembly stability of the lens. Therefore, by restricting 3.94≤fz / d1s≤4.51 and 2.22mm≤EP13×(R3 / R6)≤4.20mm, the edge thickness of the second lens and the third lens is indirectly controlled within a reasonable range on the basis of ensuring performance requirements and compact structure, the shape of the second lens and the third lens is optimized, the shape rationality is ensured, the processing feasibility of the second lens and the third lens is ensured, the deformation amount thereof during assembly is reduced, the field curvature is optimized, the assembly stability is improved, and the imaging quality is ensured.

[0069] Of course, the present embodiment can also include other parameter formulas in the above embodiments, which will not be described here.

[0070] 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 software and / or tools such as the above, the surface shape of each lens can be simulated according to the surface shape provided by the software and / or tools used and appropriately adjusted.

[0071] Optionally, the visual system described above can also include a protective glass for protecting the photosensitive elements located on the image plane.

[0072] The visual system in the present application can use multiple lenses, for example, four lenses as described above. In the present application, at least one of the mirror surfaces of each lens is an aspherical mirror surface. The characteristic of the aspherical lens is that the curvature is continuously changed from the center of the lens to the periphery of the lens. Unlike the spherical lens which has a constant curvature from the center of the lens to the periphery of the lens, the aspherical lens has better curvature radius characteristics and has the advantages of improving the distortion aberration and improving the astigmatism aberration. After using the aspherical lens, the aberration that occurs during imaging can be eliminated as much as possible, thereby improving the imaging quality.

[0073] However, those skilled in the art will appreciate that the number of lenses making up the visual system can be varied without departing from the technical solutions claimed in the present application, to obtain the various results and advantages described in the present specification. For example, although described in the embodiments by way of example with four lenses, the visual system is not limited to including four lenses. If necessary, the visual system can also include other numbers of lenses.

[0074] Figure 1 The size annotation diagram of one visual system of the present application is shown, Figure 1 The parameters D0s, D3s, D1s, d3s, d1s, d0s, d1m, d3m, D1m, D3m, d0m, D0m, EP01, EP13, L, CP1 and CP3 are marked 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, the parameters are no longer embodied in the figure when the specific embodiments are described below.

[0075] The specific surface shape and parameters of the visual system applicable to the above embodiments are further described below with reference to the drawings.

[0076] It should be noted that there are three examples of embodiment 1-1, embodiment 1-2 and embodiment 1-3 in the following embodiment one, there are three examples of embodiment 2-1, embodiment 2-2 and embodiment 2-3 in the following embodiment two, and there are three examples of embodiment 3-1, embodiment 3-2 and embodiment 3-3 in the following embodiment three. The parameters of the optical system in the visual system in the three examples in the same embodiment are the same, specifically, the curvature radius, central thickness and other parameters of the first lens to the fourth lens of the visual system and the interval distance and high-order coefficient between the lenses are the same, but the thickness, inner diameter and outer diameter of the lens barrel, the first spacing element and the third spacing element are different.

[0077] It should be noted that any one of the following embodiments one to three is applicable to all embodiments of the present application.

[0078] Embodiment one

[0079] As shown in the following figure, Figures 2 to 5 the visual system of embodiment one is described. Figure 2 The structure diagram of the visual system of embodiment 1-1 is shown, Figure 3 The structure diagram of the visual system of embodiment 1-2 is shown, Figure 4 The structure diagram of the visual system of embodiment 1-3 is shown.

[0080] As shown in the following figure, 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, arranged sequentially along the optical axis from the first side to the second side within the lens barrel P0. A polarizer LP, a reflective polarizing element RP, and a quarter-wave plate QWP are arranged sequentially on the first side of the first lens, close to the first lens E1. A reflective element BS is also provided on the second side of the fourth lens. The second lens E2 and the third lens E3 are cemented together to form a cemented lens.

[0081] In this embodiment, the light emitted from the image plane IMG is transmitted sequentially through the fourth lens E4, the third lens E3, the second lens E2, and the first lens E1, and then incident on the reflective polarizing element RP. After being reflected by the reflective polarizing element RP, it is transmitted toward the display side. Then, after being transmitted sequentially through the first lens E1, the second lens E2, the third lens E3, and the fourth lens E4, it is incident on the reflective element BS. After being reflected by the reflective element BS, it is transmitted toward the human eye side. Then, after being transmitted sequentially through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter-wave plate QWP, the reflective polarizing element RP, and the polarizer LP, it is incident on the human eye to form an image.

[0082] like Figure 2 The diagram shown is a schematic representation of the visual system in Embodiment 1-1. In this example, the first and second sides of the first spacer element P1 abut against the second side of the first lens and the first side of the second lens, respectively. The first and second sides of the third spacer element P3 abut against the second side of the third lens and the first side of the fourth lens, respectively.

[0083] like Figure 3 The diagram shown is a structural schematic of the visual system in Embodiment 1-2. In this example, the contact method of each spacer element is the same as in Embodiment 1-1, and can be referred to the relevant description in Embodiment 1-1, which will not be repeated here.

[0084] like Figure 4 The diagram shown is a structural schematic of the visual system in Embodiments 1-3. In this example, the bearing and contact method of each spacer element is the same as in Embodiment 1-1, and can be referred to the relevant description in Embodiment 1-1, which will not be repeated here.

[0085] In summary, the structural parameters of the visual system of Embodiment 1 under Embodiments 1-1, 1-2, and 1-3 are shown in Table 2 (unit: mm).

[0086] Table 2

[0087] Parameter / Embodiment 1-1 1-2 1-3 d1s 42.475 42.401 42.609 d1m 42.475 42.401 42.609 D1s 54.986 55.101 55.351 D1m 54.986 55.101 55.351 d3s 50.500 51.176 50.626 d3m 50.500 51.176 50.626 D3s 59.913 59.313 59.313 D3m 59.913 59.313 59.313 d0s 42.194 41.186 43.494 d0m 65.547 63.209 62.635 D0s 60.501 63.026 62.105 D0m 70.000 68.800 70.031 EP01 4.688 4.688 5.338 CP1 0.050 0.050 0.050 EP13 5.732 5.732 5.815 CP3 0.050 0.050 0.050 L 23.000 20.500 21.150

[0088] In the embodiment one, the first side surface of the first lens is concave, and the second side surface of the first lens is convex. The first side surface of the second lens is concave, and the second side surface of the second lens is convex. The first side surface of the third lens is concave, and the second side surface of the third lens is convex. The first side surface of the fourth lens is concave, and the second side surface of the fourth lens is convex.

[0089] In the embodiment one, the effective focal length f of the visual system is 31.33 mm, the effective focal length f1 of the first lens is 191.67 mm, the effective focal length f2 of the second lens is -703.39 mm, the effective focal length f3 of the third lens is -712.47 mm, the effective focal length f4 of the fourth lens is 329.13 mm, the combined focal length f23 of the second lens and the third lens is -172.25 mm, the combined focal length fz of the reflective polarizing element, the quarter-wave plate and the first lens is 191.13 mm, and the on-axis distance TD from the first side surface of the first lens to the second side surface of the fourth lens is 15.47 mm.

[0090] Table 3 shows the basic structural parameter table of the visual system of the embodiment one, wherein the units of the curvature radius and the thickness / distance are millimeters (mm).

[0091] Table 3

[0092]

[0093]

[0094] In the embodiment one, the first side surface and the second side surface of the first lens E1 to the fourth lens E4 are all aspheric surfaces, and the surface type of each aspheric lens can be defined by, but not limited to, the following aspheric formula:

[0095]

[0096] wherein x is the distance sag of the aspheric surface at a height of h along the optical axis direction from the vertex of the aspheric surface; c is the paraxial curvature of the aspheric surface, c = 1 / R, i.e. the paraxial curvature c is the inverse of the curvature radius R in Table 3 above; k is the conic coefficient; and Ai is the correction coefficient of the i-th order of the aspheric surface. Table 4 below shows the high-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the aspheric surfaces S21-S28 which can be used in the embodiment one.

[0097] Table 4

[0098]

[0099]

[0100] Figure 5The MTF curve of the visual system of embodiment one is shown. As can be seen from the figure, the MTF curve is high, indicating that the imaging quality at this spatial frequency is good.

[0101] Embodiment two

[0102] As Figures 6 to 9 shown, the visual system of embodiment two is described. Figure 6 A structural schematic diagram of the visual system of embodiment 2-1 is shown, Figure 7 A structural schematic diagram of the visual system of embodiment 2-2 is shown, Figure 8 A structural schematic diagram of the visual system of embodiment 2-3 is shown.

[0103] 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 arranged in the lens barrel P0 in sequence from a first side to a second side along an optical axis. A polarizer LP, a reflective polarizing element RP, and a quarter-wave plate QWP are arranged in sequence on a first side of the first lens E1 in a direction close to the first lens E1. A reflective element BS is also arranged on a first side of the fourth lens. The second lens E2 and the third lens E3 are cemented to form a cemented lens.

[0104] In this embodiment, the light rays emitted from the image plane IMG pass through the fourth lens E4, the third lens E3, the second lens E2, and the first lens E1 in sequence, are incident on the reflective polarizing element RP, are transmitted toward the display side after being reflected by the reflective polarizing element RP, pass through the first lens E1, the second lens E2, and the third lens E3 in sequence, are incident on the reflective element BS, are transmitted toward the human eye side after being reflected by the reflective element BS, and pass through the third lens E3, the second lens E2, the first lens E1, the quarter-wave plate QWP, the reflective polarizing element RP, and the polarizer LP in sequence, are incident on the human eye to form an image.

[0105] As Figure 6 shown, a structural schematic diagram of the visual system of embodiment 2-1 is shown. In this example, the first side and the second side of the first spacer element P1 abut against the second side of the first lens and the first side of the second lens, respectively. The first side and the second side of the third spacer element P3 abut against the second side of the third lens and the first side of the fourth lens, respectively.

[0106] As Figure 7 shown, a structural schematic diagram of the visual system of embodiment 2-2 is shown. In this example, the abutting modes of the spacer elements are the same as those of embodiment 2-1, and reference can be made to the related description in embodiment 2-1, which will not be described herein.

[0107] AsFigure 8 Fig. 2-3 is a structural schematic diagram of the visual system of Example 2-3. In this example, the abutting mode of each spacer element is the same as that of Example 2-1, and the relevant description in Example 2-1 can be referred to, which will not be repeated here.

[0108] In summary, the structural parameters of the visual system of Example 2 under Examples 2-1, 2-2 and 2-3 are shown in Table 5 (unit: mm).

[0109] Table 5

[0110]

[0111]

[0112] In Example 2, 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.

[0113] In Example 2, the effective focal length f of the visual system is 29.43 mm, the effective focal length f1 of the first lens is 163.66 mm, the effective focal length f2 of the second lens is -881.34 mm, the effective focal length f3 of the third lens is -400.60 mm, the effective focal length f4 of the fourth lens is 206.91 mm, the combined focal length f23 of the second lens and the third lens is -272.63 mm, the combined focal length fz of the reflective polarizing element, the quarter-wave plate and the first lens is 163.11 mm, and the on-axis distance TD from the first side surface of the first lens to the second side surface of the fourth lens is 15.54 mm.

[0114] Table 6 shows the basic structural parameter table of the visual system of Example 2, wherein the units of the curvature radius and the thickness / distance are millimeters (mm).

[0115] Table 6

[0116]

[0117]

[0118] The following Table 7 shows the high-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of each aspheric surface that can be used in Example 2.

[0119] Table 7

[0120] Coefficient / Surface 19 20 21 22 23 24 25 26 A4 -1.6055E-05 7.6675E-06 -3.8963E-06 -8.3290E-06 -8.3290E-06 -5.7565E-06 -8.3290E-06 7.6675E-06 A6 3.0907E-08 -1.2880E-09 6.2957E-10 7.9998E-09 7.9998E-09 -6.1651E-09 7.9998E-09 -1.2880E-09 A8 -2.5572E-11 9.3303E-12 -1.0038E-12 -8.6608E-12 -8.6608E-12 9.2025E-12 -8.6608E-12 9.3303E-12 A10 0.0000E+00 0.0000E+00 0.0000E+00 2.9829E-15 2.9829E-15 -4.5013E-15 2.9829E-15 0.0000E+00 A12 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 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 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 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 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 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

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

[0122] Embodiment three

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

[0124] As shown in Figures 10 to 12 , 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 arranged in the lens barrel P0 in sequence from the first side to the second side along the optical axis. A polarizer LP, a reflective polarizing element RP, and a quarter-wave plate QWP are arranged in sequence on the first side of the first lens E1 in a direction close to the first lens E1. A reflective element BS is also arranged on the second side of the third lens. The second lens E2 and the third lens E3 are cemented to form a cemented lens.

[0125] In this embodiment, the light rays emitted from the image plane IMG pass through the fourth lens E4, the third lens E3, the second lens E2, and the first lens E1 in sequence, are incident on the reflective polarizing element RP, are transmitted toward the display side after being reflected by the reflective polarizing element RP, pass through the first lens E1, the second lens E2, and the third lens E3 in sequence, are incident on the reflective element BS, are transmitted toward the human eye side after being reflected by the reflective element BS, and pass through the third lens E3, the second lens E2, the first lens E1, the quarter-wave plate QWP, the reflective polarizing element RP, and the polarizer LP in sequence, are incident on the human eye to form an image.

[0126] As shown in Figure 10 , a structural schematic diagram of the visual system of embodiment 3-1 is shown. In this example, the first side and the second side of the first spacer element P1 abut against the second side of the first lens and the first side of the second lens, respectively. The first side and the second side of the third spacer element P3 abut against the second side of the third lens and the first side of the fourth lens, respectively.

[0127] As shown in Figure 11 , a structural schematic diagram of the visual system of embodiment 3-2 is shown. In this example, the abutting modes of the spacer elements are the same as those of embodiment 3-1, and reference can be made to the related descriptions in embodiment 3-1, which will not be described herein.

[0128] As Figure 12 shown, it is a structural schematic diagram of the visual system of Example 3-3. In this example, the abutting mode of each spacer element is the same as that of Example 3-1, and the relevant description in Example 3-1 can be referred to, which will not be repeated here.

[0129] In summary, the structural parameters of the visual system of Example Three under Example 3-1, Example 3-2, and Example 3-3 are shown in Table 8 (unit: mm).

[0130] Table 8

[0131] Parameter / Embodiment 3-1 3-2 3-3 d1s 44.020 45.393 43.876 d1m 43.727 47.301 43.580 D1s 50.963 52.361 52.387 D1m 52.392 54.455 52.626 d3s 53.861 53.112 52.256 d3m 54.614 53.805 49.689 D3s 56.964 57.429 56.661 D3m 57.542 56.998 57.542 d0s 41.281 44.638 43.097 d0m 64.634 63.096 64.634 D0s 59.588 55.832 57.748 D0m 68.614 65.197 67.249 EP01 3.752 4.686 3.605 CP1 2.212 3.121 2.411 EP13 4.454 3.910 4.753 CP3 4.158 3.794 3.362 L 23.100 19.914 20.140

[0132] In Example Three, 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.

[0133] In Example Three, the effective focal length f of the visual system is 33.05 mm, the effective focal length f1 of the first lens is 182.70 mm, the effective focal length f2 of the second lens is -932.72 mm, the effective focal length f3 of the third lens is -333.28 mm, the effective focal length f4 of the fourth lens is -3388.33 mm, the combined focal length f23 of the second lens and the third lens is -241.97 mm, the combined focal length fz of the reflective polarizing element, the quarter-wave plate, and the first lens is 181.95 mm, and the on-axis distance TD from the first side surface of the first lens to the second side surface of the fourth lens is 17.31 mm.

[0134] Table 9 shows the basic structural parameter table of the visual system of Example Three, wherein the units of the curvature radius and the thickness / distance are millimeters (mm).

[0135] Table 9

[0136]

[0137] The following Table 10 gives the high-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 of each aspheric surface that can be used in Example Three.

[0138] Table 10

[0139]

[0140]

[0141] Figure 13The MTF curve of the visual system of Example Three is shown in the figure. It can be seen that the MTF curve is high, indicating that the imaging quality at this spatial frequency is good.

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

[0143] Table 11

[0144] Conditional / Embodiment 1-1 1-2 1-3 2-1 2-2 2-3 3-1 3-2 3-3 fz / d1s 4.50 4.51 4.49 3.95 3.96 3.94 4.13 4.01 4.15 EP13 / (CT2+CT3) 1.43 1.43 1.45 1.44 1.44 1.35 1.11 0.98 1.19 EP01 / (CTL+CTR+CTQ) 31.25 31.25 35.59 29.61 36.94 31.55 25.01 31.24 24.03 R1 / d0s -1.31 -1.34 -1.27 -1.13 -1.07 -1.15 -1.04 -0.97 -1.00 d1m / R2 -1.20 -1.19 -1.20 -1.37 -1.36 -1.37 -1.47 -1.59 -1.46 f23 / (D1s+D3s) -1.50 -1.51 -1.50 -2.42 -2.39 -2.42 -2.24 -2.20 -2.22 EP13x(R3 / R6)(mm) 2.22 2.22 2.25 4.20 4.20 3.94 3.31 2.90 3.53 f1 / D1m 3.49 3.48 3.46 3.04 2.98 2.98 3.49 3.36 3.47 f / L 1.36 1.53 1.48 1.28 1.33 1.32 1.43 1.66 1.64 TD / (CP1+EP13+CP3) 2.65 2.65 2.62 2.66 2.66 2.35 1.60 1.60 1.64 (D0m-d0m) / CT4 1.48 1.86 2.47 1.32 1.49 1.78 1.33 0.70 0.87 f3 / (d3s+d3m) -2.29 -2.26 -2.28 -3.97 -3.98 -3.77 -3.07 -3.12 -3.27 (R7+R8) / D3m -1.99 -2.01 -2.01 -1.22 -1.22 -1.25 -1.47 -1.49 -1.47 D0s / TD 3.91 4.07 4.01 3.84 3.95 3.74 3.44 3.22 3.34 d0s / CT1 14.06 13.73 14.50 13.76 14.58 13.56 13.90 15.04 14.52 f / (D0m-D0s) 3.30 5.43 3.95 3.27 4.98 2.80 3.66 3.53 3.48

[0145] Table 12 shows the effective focal length of the visual system of Examples One to Three and the effective focal length of each lens and other parameters.

[0146] Table 12

[0147] Parameter / Embodiment 1-1 1-2 1-3 2-1 2-2 2-3 3-1 3-2 3-3 f (mm) 31.33 31.33 31.33 29.43 29.43 29.43 33.05 33.05 33.05 f1 (mm) 191.67 191.67 191.67 163.66 163.66 163.66 182.70 182.70 182.70 f2 (mm) -703.39 -703.39 -703.39 -881.34 -881.34 -881.34 -932.72 -932.72 -932.72 f3 (mm) -230.84 -230.84 -230.84 -400.60 -400.60 -400.60 -333.28 -333.28 -333.28 f4 (mm) 329.13 329.13 329.13 206.91 206.91 206.91 -3388.33 -3388.33 -3388.33 f23 (mm) -172.25 -172.25 -172.25 -272.63 -272.63 -272.63 -241.97 -241.97 -241.97 fz (mm) 191.13 191.13 191.13 163.11 163.11 163.11 181.95 181.95 181.95 TD (mm) 15.47 15.47 15.47 15.54 15.54 15.54 17.31 17.31 17.31

[0148] The present application also provides an imaging device, the electronic photosensitive element of which can be a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor device (CMOS). The imaging device can be a stand-alone imaging apparatus 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.

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

[0150] Obviously, the above-described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work should fall within the protection scope of the present application.

[0151] It should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise, and it should be understood that, when the terms "comprise" and / or "include" are used in the specification, there is a presence of a feature, step, work, device, component and / or combination thereof.

[0152] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data used in this way 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.

[0153] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A visual system, characterized in that, It includes a lens barrel and a lens assembly and a spacer assembly disposed within the lens barrel. The lens group consists of four lenses, a polarizer, a reflective polarizing element, and a quarter-wave plate. The four lenses, from the first side to the second side, are sequentially arranged as a first lens with positive optical power, a second lens with negative optical power, a third lens with negative optical power, and a fourth lens with either positive or negative optical power. The first lens has a concave first side and a convex second side; the second lens has a concave first side and a convex second side; the third lens has a concave first side and a convex second side; and the fourth lens has a concave first side and a convex second side. The second lens and the third lens are cemented together to form a cemented lens. The polarizer, the reflective polarizing element, and the quarter-wave plate are sequentially arranged on the first side of the first lens along the direction close to the first 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 of the first lens, and a third spacer element located between the third lens and the fourth lens and abutting against a second side of the third lens; The combined focal length fz of the polarizer, the reflective polarizing element, the quarter-wave plate, and the first lens satisfies the following relationship with the inner diameter d1s of the first side of the first spacer: 3.94 ≤ fz / d1s ≤ 4.51; the spacing distance EP13 between the second side of the first spacer and the first side of the third spacer on the optical axis of the visual system, the center thickness CT2 of the second lens on the optical axis, and the center thickness CT3 of the third lens on the optical axis satisfy the following relationship: 0.98 ≤ EP13 / (CT2+CT3) ≤ 1.

45.

2. The visual system according to claim 1, characterized in that, The distance EP01 between the first side of the lens barrel and the first side of the first spacer element on the optical axis, the center thickness CTL of the polarizer on the optical axis, the center thickness CTR of the reflective polarizing element on the optical axis, and the center thickness CTQ of the quarter-wave plate on the optical axis satisfy the following: 24.03≤EP01 / (CTL+CTR+CTQ)≤36.

94.

3. The visual system according to claim 1, characterized in that, The radius of curvature R1 of the first side surface of the first lens and the inner diameter d0s of the first side surface of the lens barrel satisfy the following condition: -1.34≤R1 / d0s≤-0.

97.

4. The visual system according to claim 1, characterized in that, The inner diameter d1m of the second side of the first spacer element and the radius of curvature R2 of the second side of the first lens satisfy the following condition: -1.59≤d1m / R2≤-1.

19.

5. 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 D1s of the first side of the first spacer element and the outer diameter D3s of the first side of the third spacer element satisfy the following: -2.42≤f23 / (D1s+D3s)≤-1.

50.

6. The visual system according to claim 1, characterized in that, The distance EP13 between the second side of the first spacer element and the first side of the third spacer element on the optical axis, the radius of curvature R3 of the first side of the second lens and the radius of curvature R6 of the second side of the third lens satisfy the following: 2.22mm≤EP13×(R3 / R6)≤4.20mm.

7. The visual system according to claim 1, characterized in that, The effective focal length f1 of the first lens and the outer diameter D1m of the second side of the first spacer element satisfy the following condition: 2.98≤f1 / D1m≤3.

49.

8. The visual system according to claim 1, characterized in that, The effective focal length f of the visual system 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 the following condition: 1.28 ≤ f / L ≤ 1.

66.

9. The visual system according to claim 1, characterized in that, The axial distance TD between the first side surface of the first lens and the second side surface of the fourth lens, the maximum axial thickness CP1 of the first spacer element, the spacing distance EP13 between the second side surface of the first spacer element and the first side surface of the third spacer element on the optical axis, and the maximum axial thickness CP3 of the third spacer element satisfy the following condition: 1.60≤TD / (CP1+EP13+CP3)≤2.

66.

10. 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 d0m of the second side of the lens barrel, and the center thickness CT4 of the fourth lens on the optical axis satisfy the following condition: 0.70≤(D0m-d0m) / CT4≤2.

47.

11. The visual system according to claim 1, characterized in that, The effective focal length f3 of the third lens, the inner diameter d3s of the first side of the third spacer element, and the inner diameter d3m of the second side of the third spacer element satisfy the following: -3.98≤f3 / (d3s+d3m)≤-2.

26.

12. The visual system according to claim 1, characterized in that, The radius of curvature R7 of the first side of the fourth lens, the radius of curvature R8 of the second side of the fourth lens, and the outer diameter D3m of the second side of the third spacer element satisfy the following condition: -2.01≤(R7+R8) / D3m≤-1.

22.

13. The visual system according to any one of claims 1 to 12, characterized in that, The outer diameter D0s of the first side of the lens barrel and the axial distance TD from the first side of the first lens to the second side of the fourth lens satisfy the following condition: 3.22≤D0s / TD≤4.

07.

14. The visual system according to any one of claims 1 to 12, characterized in that, The inner diameter d0s of the first side of the lens barrel and the center thickness CT1 of the first lens on the optical axis satisfy the following condition: 13.56≤d0s / CT1≤15.

04.

15. The visual system according to any one of claims 1 to 12, characterized in that, The effective focal length f of the visual system, the outer diameter D0m of the second side of the lens barrel and the outer diameter D0s of the first side of the lens barrel satisfy the following condition: 2.80≤f / (D0m-D0s)≤5.

43.

16. The visual system according to any one of claims 1 to 12, characterized in that, The visual system also includes a reflective element located between the third lens and the image surface of the visual system.

Images