Large-aperture athermalization wide-angle monitoring lens and imaging method thereof

Abstract

The invention relates to a large-aperture athermalization wide-angle monitoring lens and an imaging method thereof, an optical system of the lens has five lenses with focal power, and the five lenses are sequentially a first lens, a second lens, a third lens, a fourth lens and a fifth lens along the incident direction of an optical path; a diaphragm is arranged between the second lens and the third lens; the first lens is a meniscus negative lens, the object side surface is a convex surface, and the image side surface is a concave surface; the second lens is a meniscus positive lens or a meniscus negative lens, the object side surface is a concave surface, and the image side surface is a convex surface; the third lens is a biconvex positive lens; the fourth lens is a biconcave negative lens or a meniscus negative lens of which the object side surface is a convex surface and the image side surface is a concave surface; the fifth lens is a biconvex positive lens; wherein the first lens and the third lens are glass spherical lenses, and the second lens, the fourth lens and the fifth lens are plastic aspheric lenses.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to a large-aperture, calorimetric, wide-angle surveillance lens and its imaging method. Background Technology

[0002] With the development of science and technology and the improvement of living standards, security monitoring systems are becoming increasingly popular worldwide, with a wider range of applications. The global security monitoring industry is developing rapidly, and the market size is constantly expanding. Wide-angle monitoring lenses, due to their large field of view and wide viewing range, have attracted much market attention. However, most wide-angle lenses currently on the market generally suffer from problems such as small aperture, large temperature drift, poor stability at high and low temperatures, and poor night vision capabilities. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a large-aperture, athermalized wide-angle surveillance lens and its imaging method, which has the advantages of large aperture, large field of view, high resolution, and day and night confocality, while having low temperature drift and being able to achieve athermalization function in the range of -30℃ to 80℃.

[0004] This invention is achieved using the following scheme: a large-aperture, heat-free wide-angle surveillance lens, wherein the optical system of the lens has five lenses with optical power, arranged sequentially along the incident direction of the light path as a first lens, a second lens, a third lens, a fourth lens, and a fifth lens; an aperture stop is provided between the second and third lenses; the first lens is a meniscus negative lens with a convex object side and a concave image side; the second lens is a meniscus positive lens with a concave object side and a convex image side; the third lens is a biconvex positive lens; the fourth lens is a meniscus negative lens with a convex object side and a concave image side; and the fifth lens is a biconvex positive lens; wherein the first and third lenses are glass spherical lenses, and the second, fourth, and fifth lenses are plastic aspherical lenses.

[0005] Furthermore, the focal length of the optical system is f, and the focal lengths of the first lens, second lens, third lens, fourth lens, and fifth lens are f1, f2, f3, f4, and f5, respectively, wherein f1, f2, f3, f4, and f5 satisfy the following ratio with f: -2.0 <f1 / f<-1.0,27.0<f2 / f<28.0,1.0<f3 / f<2.0,-2.0<f4 / f<1.0,1.0<f5 / f<2.0。

[0006] Furthermore, the first lens satisfies the following relationship: N d ≤1.5, V d ≥50.0; The second lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The third lens satisfies the relationship: 1.5≤N d≤1.8, V d ≥50.0; The fourth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The fifth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; where N d V is the refractive index. d Let be Abbe's constant.

[0007] Furthermore, the air gap between the first lens and the second lens is 2.5~3.0mm; the air gap between the second lens and the aperture stop is 0~0.5mm; the air gap between the aperture stop and the third lens is -0.5~0mm; the air gap between the third lens and the fourth lens is 0~0.5mm; and the air gap between the fourth lens and the fifth lens is 0~0.5mm.

[0008] Furthermore, the total optical length (TTL) of the optical system and the focal length (f) of the optical system satisfy the following conditions: 3.0 ≤ TTL / f ≤ 4.0; the F-number of the optical system ≤ 1.6; and the image height (H) of the optical system and the focal length (f) of the optical system satisfy the following condition: H / f ≥ 1.5.

[0009] Furthermore, a filter is provided on the rear side of the fifth lens.

[0010] An imaging method for a large-aperture, heat-free wide-angle surveillance lens as described above, wherein light passes sequentially through a first lens, a second lens, an aperture stop, a third lens, a fourth lens, a fifth lens, and a filter before forming an image.

[0011] Another technical solution of the present invention: a large-aperture, heat-free wide-angle surveillance lens, wherein the optical system of the lens has five lenses with optical power, arranged sequentially along the incident direction of the light path as a first lens, a second lens, a third lens, a fourth lens, and a fifth lens; an aperture stop is provided between the second and third lenses; the first lens is a meniscus negative lens with a convex object side and a concave image side; the second lens is a meniscus negative lens with a concave object side and a convex image side; the third lens is a biconvex positive lens; the fourth lens is a biconcave negative lens; and the fifth lens is a biconvex positive lens; wherein the first and third lenses are glass spherical lenses, and the second, fourth, and fifth lenses are plastic aspherical lenses.

[0012] Furthermore, the focal length of the optical system is f, and the focal lengths of the first, second, third, fourth, and fifth lenses are f1, f2, f3, f4, and f5, respectively, where f1, f2, f3, f4, and f5 satisfy the following ratio with f: -2.0 <f1 / f<-1.0,-15.0<f2 / f<-14.0,1.0<f3 / f<2.0,-3.0<f4 / f<-2.0,1.0<f5 / f<2.0。

[0013] Furthermore, the first lens satisfies the following relationship: N d ≤1.5, V d ≥50.0; The second lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The third lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The fourth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The fifth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; where N d V is the refractive index. d Let be Abbe's constant.

[0014] Furthermore, the air gap between the first lens and the second lens is 2.0~2.5mm; the air gap between the second lens and the aperture stop is -0.5~0mm; the air gap between the aperture stop and the third lens is 0~0.5mm; the air gap between the third lens and the fourth lens is 2.0~2.5mm; and the air gap between the fourth lens and the fifth lens is 0~0.5mm.

[0015] Furthermore, the total optical length (TTL) of the optical system and the focal length (f) of the optical system satisfy the following conditions: 3.0 ≤ TTL / f ≤ 4.0; the F-number of the optical system ≤ 2.0; and the image height (H) of the optical system and the focal length (f) of the optical system satisfy the following condition: H / f ≥ 1.5.

[0016] Furthermore, a filter is provided on the rear side of the fifth lens.

[0017] An imaging method for a large-aperture, heat-free wide-angle surveillance lens as described above, wherein light passes sequentially through a first lens, a second lens, an aperture stop, a third lens, a fourth lens, a fifth lens, and a filter before forming an image.

[0018] Compared with existing technologies, the present invention has the following advantages: The large-aperture, pyrolysis-free wide-angle surveillance lens of the present invention uses five lenses, consisting of two glass spherical lenses and three plastic aspherical lenses to form an optical imaging system. By optimizing the surface shape of the lenses, rationally allocating the optical power of each lens and the position of the aperture stop, the lens has a large field of view and high resolution, a wide monitoring range, and good image quality; at the same time, it has a large aperture and high edge illumination, ensuring the brightness and clarity of the monitoring image under different lighting conditions; it also takes into account the defocus of infrared light, enabling the lens to achieve day and night confocal performance; all five lenses are made of materials with negative refractive index temperature coefficient, minimizing the defocus caused by temperature changes, achieving pyrolysis function, and ensuring high-definition imaging in environments from -30℃ to 80℃.

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through specific embodiments and related drawings. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the optical system structure of Embodiment 1 of the present invention; Figure 2 This is the MTF curve of Embodiment 1 of the present invention at room temperature; Figure 3 This is the MTF curve of Embodiment 1 of the present invention at a low temperature of -30°C; Figure 4 This is the MTF curve of Embodiment 1 of the present invention at a high temperature of 80°C; Figure 5 This is a schematic diagram of the optical system structure of Embodiment 2 of the present invention; Figure 6 This is the MTF curve of Embodiment 2 of the present invention at room temperature; Figure 7 This is the MTF curve of Embodiment 2 of the present invention at a low temperature of -30°C; Figure 8 This is the MTF curve of Embodiment 2 of the present invention at a high temperature of 80°C; In the diagram: STO - aperture stop; L1 - first lens; L2 - second lens; L3 - third lens; L4 - fourth lens; L5 - fifth lens; L6 - equivalent glass plate; IMA - imaging plane. Detailed Implementation

[0021] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] Example 1: like Figure 1 As shown, a large-aperture, heat-free wide-angle surveillance lens is disclosed. The optical system of the lens comprises five lenses with optical power, arranged sequentially along the incident light path as a first lens, a second lens, a third lens, a fourth lens, and a fifth lens. An aperture stop is provided between the second and third lenses. The first lens is a meniscus negative lens with a convex object side and a concave image side. The second lens is a meniscus positive lens with a concave object side and a convex image side. The third lens is a biconvex positive lens. The fourth lens is a meniscus negative lens with a convex object side and a concave image side. The fifth lens is a biconvex positive lens. The positive and negative signs of the lenses refer to their optical power. The first and third lenses are glass spherical lenses, while the second, fourth, and fifth lenses are plastic aspherical lenses.

[0024] The first lens has negative optical power, with its object-side surface convex and its image-side surface concave. This facilitates the adjustment of large-angle light and allows for a smaller front aperture. Furthermore, the first lens uses glass, improving its environmental reliability and making it more suitable for outdoor use. The second lens has either positive or negative optical power, with its object-side surface concave and its image-side surface convex. This helps correct system aberrations and improves the imaging performance of the optical system. The third lens has positive optical power, with both its object-side and image-side surfaces convex, which promotes a smoother light transition.

[0025] The second, fourth, and fifth lenses are all plastic aspherical lenses, which are beneficial for optimizing on-axis and off-axis aberrations and further improving imaging quality. The first and third lenses are both glass lenses with negative refractive index temperature coefficients, which gives the optical lens a small temperature drift and ensures high-definition imaging in the range of -30℃ to 80℃.

[0026] The second, fourth, and fifth lenses are all aspherical lenses. The equation for an aspherical curve is:

[0027] Where Z is the distance from the vertex of the aspherical surface to the optical axis at a height of h; c is the paraxial curvature of the aspherical surface; and k is the conic constant. , , , , , , , All are coefficients of higher-order terms.

[0028] The aspherical coefficients of the aspherical lenses in the optical system of this embodiment are shown in the table below:

[0029] In this embodiment, the focal length of the optical system is f, and the focal lengths of the first lens, second lens, third lens, fourth lens, and fifth lens are f1, f2, f3, f4, and f5, respectively, wherein f1, f2, f3, f4, and f5 satisfy the following ratio with f: -2.0 <f1 / f<-1.0,27.0<f2 / f<28.0,1.0<f3 / f<2.0,-2.0<f4 / f<1.0,1.0<f5 / f<2.0。

[0030] In this embodiment, the first lens satisfies the following relationship: N d ≤1.5, V d ≥50.0; The second lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The third lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The fourth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The fifth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; where N d V is the refractive index. d Let be Abbe's constant.

[0031] In this embodiment, the air gap between the first and second lenses is 2.5~3.0mm; the air gap between the second lens and the aperture stop is 0~0.5mm; the air gap between the aperture stop and the third lens is -0.5~0mm; the air gap between the third and fourth lenses is 0~0.5mm; and the air gap between the fourth and fifth lenses is 0~0.5mm. By rationally matching the optical power, surface shape, air gap, and aperture stop position of each lens, the aberrations and defocusing caused by temperature changes in the optical system are fully corrected, giving the lens high resolution and pyrolysis capability. Figures 2 to 4 As shown.

[0032] In this embodiment, the total optical length (TTL) of the optical system and the focal length (f) of the optical system satisfy the following conditions: 3.0 ≤ TTL / f ≤ 4.0; the F-number of the optical system ≤ 1.6; and the image height (H) of the optical system and the focal length (f) of the optical system satisfy the following condition: H / f ≥ 1.5.

[0033] In this embodiment, a filter is provided on the rear side of the fifth lens.

[0034] The technical specifications achieved by the optical system in this embodiment are as follows: (1) Focal length: 3.5≤EFFL≤4.0mm; (2) Aperture F≤1.6; (3) Field of view: 2w ≥ 110°; (4) Relative illumination: RI ≥ 70%; (5) Operating bands: visible light band and short-wave infrared light band; (6) Operating temperature: -30℃~80℃.

[0035] To achieve the above design parameters, the specific design of the optical system adopted in this embodiment is shown in the table below:

[0036] An imaging method for a large-aperture, heat-free wide-angle surveillance lens as described above, wherein light passes sequentially through a first lens, a second lens, an aperture stop, a third lens, a fourth lens, a fifth lens, and a filter before forming an image.

[0037] Example 2: like Figure 5 As shown, a large-aperture, heat-free wide-angle surveillance lens is disclosed. The optical system of the lens comprises five lenses with optical power, arranged sequentially along the incident light path as a first lens, a second lens, a third lens, a fourth lens, and a fifth lens. An aperture stop is provided between the second and third lenses. The first lens is a meniscus negative lens with a convex object side and a concave image side. The second lens is also a meniscus negative lens with a concave object side and a convex image side. The third lens is a biconvex positive lens. The fourth lens is a biconcave negative lens. The fifth lens is a biconvex positive lens. The positive and negative signs of the lenses refer to their optical power. The first and third lenses are glass spherical lenses, while the second, fourth, and fifth lenses are plastic aspherical lenses.

[0038] The first lens has negative optical power, with its object-side surface convex and its image-side surface concave. This facilitates the adjustment of large-angle light and allows for a smaller front aperture. Furthermore, the first lens uses glass, improving its environmental reliability and making it more suitable for outdoor use. The second lens has either positive or negative optical power, with its object-side surface concave and its image-side surface convex. This helps correct system aberrations and improves the imaging performance of the optical system. The third lens has positive optical power, with both its object-side and image-side surfaces convex, which promotes a smoother light transition.

[0039] The second, fourth, and fifth lenses are all plastic aspherical lenses, which are beneficial for optimizing on-axis and off-axis aberrations and further improving imaging quality. The first and third lenses are both glass lenses with negative refractive index temperature coefficients, which gives the optical lens a small temperature drift and ensures high-definition imaging in the range of -30℃ to 80℃.

[0040] The second, fourth, and fifth lenses are all aspherical lenses. The equation for an aspherical curve is:

[0041] Where Z is the distance from the vertex of the aspherical surface to the optical axis at a height of h; c is the paraxial curvature of the aspherical surface; and k is the conic constant. , , , , , , , All are coefficients of higher-order terms.

[0042] The aspherical coefficients of the aspherical lenses in the optical system of this embodiment are shown in the table below:

[0043] In this embodiment, the focal length of the optical system is f, and the focal lengths of the first lens, second lens, third lens, fourth lens, and fifth lens are f1, f2, f3, f4, and f5, respectively, wherein f1, f2, f3, f4, and f5 satisfy the following ratio with f: -2.0 <f1 / f<-1.0,-15.0<f2 / f<-14.0,1.0<f3 / f<2.0,-3.0<f4 / f<-2.0,1.0<f5 / f<2.0。

[0044] In this embodiment, the first lens satisfies the following relationship: N d ≤1.5, V d ≥50.0; The second lens satisfies the relationship: 1.5≤N d ≤1.8, V d≥50.0; The third lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The fourth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The fifth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; where N d V is the refractive index. d Let be Abbe's constant.

[0045] In this embodiment, the air gap between the first and second lenses is 2.0~2.5mm; the air gap between the second lens and the aperture stop is -0.5~0mm; the air gap between the aperture stop and the third lens is 0~0.5mm; the air gap between the third and fourth lenses is 2.0~2.5mm; and the air gap between the fourth and fifth lenses is 0~0.5mm. By rationally matching the optical power, surface shape, air gap, and aperture stop position of each lens, the aberrations and defocusing caused by temperature changes in the optical system are fully corrected, giving the lens high resolution and pyrolysis capability. Figures 6 to 8 As shown.

[0046] In this embodiment, the total optical length TTL of the optical system and the focal length f of the optical system satisfy the following conditions: 3.0≤TTL / f≤4.0; the F-number of the optical system ≤2.0; and the image height H of the optical system and the focal length f of the optical system satisfy the following condition: H / f≥1.5.

[0047] In this embodiment, a filter is provided on the rear side of the fifth lens.

[0048] The technical specifications achieved by the optical system in this embodiment are as follows: (1) Focal length: 3.5≤EFFL≤4.0mm; (2) Aperture F≤2.0; (3) Field of view: 2w ≥ 110°; (4) Relative illumination: RI ≥ 50%; (5) Operating bands: visible light band and short-wave infrared light band; (6) Operating temperature: -30℃~80℃.

[0049] To achieve the above design parameters, the specific design of the optical system adopted in this embodiment is shown in the table below:

[0050] An imaging method for a large-aperture, heat-free wide-angle surveillance lens as described above, wherein light passes sequentially through a first lens, a second lens, an aperture stop, a third lens, a fourth lens, a fifth lens, and a filter before forming an image.

[0051] In summary, the large-aperture, calorimetric wide-angle surveillance optical system provided by this invention, through the rational allocation of the optical power, surface shape, center thickness, air gap, and aperture position of each lens, enables the lens to have a large aperture, a large field of view, and day and night confocal function, high resolution, large light-transmitting aperture, high relative illumination, and bright and clear imaging images; at the same time, it adopts a glass-plastic hybrid structure, which is low in cost and has low temperature drift, ensuring high-definition imaging in environments ranging from -30℃ to 80℃.

[0052] Unless otherwise stated, if any of the technical solutions disclosed in this invention specify a numerical range, then the disclosed numerical range is a preferred numerical range. Anyone skilled in the art should understand that the preferred numerical range is merely one among many feasible numerical values ​​that has a more obvious or representative technical effect. Because there are many numerical values, it is impossible to list them all. Therefore, this invention discloses only some numerical values ​​to illustrate the technical solutions of this invention. Furthermore, the numerical values ​​listed above should not constitute a limitation on the scope of protection of this invention.

[0053] If this invention discloses or relates to mutually fixedly connected components or structural parts, then, unless otherwise stated, a fixed connection can be understood as: a detachable fixed connection (e.g., using bolts or screws), or a non-detachable fixed connection (e.g., riveting, welding). Of course, mutually fixed connections can also be replaced by an integral structure (e.g., manufactured in one piece using a casting process) (except where it is obviously impossible to use an integral molding process).

[0054] In addition, unless otherwise stated, the terms used in any of the technical solutions disclosed in this invention to indicate positional relationships or shapes include states or shapes that are similar to, close to, or approximate with those states or shapes.

[0055] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured by a one-piece molding process.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A large-aperture, heat-free wide-angle surveillance lens, characterized in that: The optical system of the lens has five lenses with optical power, arranged sequentially along the incident light path as a first lens, a second lens, a third lens, a fourth lens, and a fifth lens; an aperture stop is provided between the second and third lenses; the first lens is a meniscus negative lens with a convex object side and a concave image side; the second lens is a meniscus positive lens or a meniscus negative lens with a concave object side and a convex image side; the third lens is a biconvex positive lens; the fourth lens is a biconcave negative lens or a meniscus negative lens with a convex object side and a concave image side; the fifth lens is a biconvex positive lens; wherein the first and third lenses are glass spherical lenses, and the second, fourth, and fifth lenses are plastic aspherical lenses.

2. The large-aperture, heat-free wide-angle surveillance lens according to claim 1, characterized in that: The second lens is a meniscus positive lens, and the fourth lens is a meniscus negative lens with a convex object side and a concave image side. The focal length of the optical system is f, and the focal lengths of the first, second, third, fourth, and fifth lenses are f1, f2, f3, f4, and f5, respectively. The ratios of f1, f2, f3, f4, and f5 to f satisfy the following proportions: -2.0 < f1 / f < -1.0, 27.0 < f2 / f < 28.0, 1.0 < f3 / f < 2.0, -2.0 < f4 / f < 1.0, and 1.0 < f5 / f < 2.

0.

3. The large-aperture, heat-free wide-angle surveillance lens according to claim 2, characterized in that: The first lens satisfies the following relationship: N d ≤1.5, V d ≥50.0; The second lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The third lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The fourth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The fifth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; where N d V is the refractive index. d Let be Abbe's constant.

4. The large-aperture, heat-free wide-angle surveillance lens according to claim 3, characterized in that: The air gap between the first lens and the second lens is 2.5~3.0mm; the air gap between the second lens and the aperture stop is 0~0.5mm; the air gap between the aperture stop and the third lens is -0.5~0mm; the air gap between the third lens and the fourth lens is 0~0.5mm; and the air gap between the fourth lens and the fifth lens is 0~0.5mm.

5. The large-aperture, heat-free wide-angle surveillance lens according to claim 1, characterized in that: The second lens is a meniscus negative lens, the fourth lens is a biconcave negative lens, and the focal length of the optical system is f. The focal lengths of the first, second, third, fourth, and fifth lenses are f1, f2, f3, f4, and f5, respectively. The ratios of f1, f2, f3, f4, and f to f satisfy the following: -2.0 < f1 / f < -1.0, -15.0 < f2 / f < -14.0, 1.0 < f3 / f < 2.0, -3.0 < f4 / f < -2.0, and 1.0 < f5 / f < 2.

0.

6. The large-aperture, heat-free wide-angle surveillance lens according to claim 5, characterized in that: The first lens satisfies the following relationship: N d ≤1.5, V d ≥50.0; The second lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The third lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The fourth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; The fifth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; where N d V is the refractive index. d Let be Abbe's constant.

7. The large-aperture, heat-free wide-angle surveillance lens according to claim 6, characterized in that: The air gap between the first lens and the second lens is 2.0~2.5mm; the air gap between the second lens and the aperture stop is -0.5~0mm; the air gap between the aperture stop and the third lens is 0~0.5mm; the air gap between the third lens and the fourth lens is 2.0~2.5mm; and the air gap between the fourth lens and the fifth lens is 0~0.5mm.

8. The large-aperture, heat-free wide-angle surveillance lens according to claim 1, characterized in that: The total optical length (TTL) of the optical system and the focal length (f) of the optical system satisfy the following condition: 3.0 ≤ TTL / f ≤ 4.0; the image height (H) of the optical system and the focal length (f) of the optical system satisfy the following condition: H / f ≥ 1.

5.

9. The large-aperture, heat-free wide-angle surveillance lens according to claim 1, characterized in that: A filter is provided on the rear side of the fifth lens.

10. An imaging method for a large-aperture, heat-free wide-angle surveillance lens as described in claim 9, characterized in that: The light rays pass through the first lens, the second lens, the aperture, the third lens, the fourth lens, the fifth lens, and the filter in sequence to form an image.

Images