Day and night co-focusing lens and imaging device

Abstract

The present invention discloses a day-night confocal lens and an imaging device. The day-night confocal lens includes a first convex-concave lens with a negative optical power, a second double-convex lens with a positive optical power, a third double-convex lens with a positive optical power, and a fourth convex-concave lens with a negative optical power, which are arranged in sequence from the object side to the image side. The total length of the day-night confocal lens is controlled within 22.4 mm, the aperture value F satisfies 1.6 ≤ F ≤ 2.0, it supports an image plane of 1 / 2.7 inch, and can also achieve clear imaging in low light. By reasonably reducing the number of lenses, the day-night confocal lens can achieve low cost and light weight. Through reasonable setting of the optical powers and shapes of the four lenses, an FNO 1.6 large aperture can be achieved, and at the same time, the resolution can reach 4M, ensuring high resolution under a large aperture, so as to provide a low-cost, large-aperture, small-sized day-night confocal lens capable of day-night confocal imaging.

Description

Technical Field

[0001] The present invention relates to the field of optical technologies, and particularly to a day-night confocal lens and an imaging device. Background Art

[0002] With the continuous development of technology, the level of mold processing is getting higher and higher, the demand for lenses in the consumer market is increasing, and the requirements are gradually rising. At present, optical lenses with low cost, high pixel, large aperture, good infrared confocal performance, and the ability to adapt to environments with large temperature differences have become the pursuit goals of the consumer market. However, many similar products have a large number of lenses and a large proportion of glass used, which is not conducive to widely promoting the application range of fixed-focus lenses in the market. Summary of the Invention

[0003] The main object of the present invention is to provide a day-night confocal lens and an imaging device, aiming to provide a small-sized day-night confocal lens with low cost, large aperture, and the ability to perform day-night confocal imaging.

[0004] To achieve the above object, a day-night confocal lens provided by the present invention has an object side and an image side arranged oppositely along the optical axis direction. The day-night confocal lens includes a first convex-concave lens with a negative optical power, a second biconvex lens with a positive optical power, a third biconvex lens with a positive optical power, and a fourth concave-convex lens with a negative optical power, which are arranged in sequence from the object side to the image side; the concave surface of the first convex-concave lens faces the image side, and the concave surface of the fourth concave-convex lens faces the object side.

[0005] The total optical length TTL of the day-night confocal lens is ≤ 22.4 mm, and the aperture value of the day-night confocal lens is F, and F = 1.6.

[0006] Optionally, the focal length of the first convex-concave lens is f1, the focal length of the second biconvex lens is f2, the focal length of the third biconvex lens is f3, and the focal length of the fourth concave-convex lens is f4, where:

[0007] -6.2 < f1 < -5.0;

[0008] 7.4 < f2 < 8.5;

[0009] 4.8 < f3 < 5.8;

[0010] -9.0 < f4 < -7.8.

[0011] Optionally, the refractive index of the first convex-concave lens is n1, the dispersion coefficient is v1, the refractive index of the second biconvex lens is n2, the dispersion coefficient is v2, the refractive index of the third biconvex lens is n3, the dispersion coefficient is v3, the refractive index of the fourth concave-convex lens is n4, and the dispersion coefficient is v4, where:

[0012] 1.54 ≤ n1 ≤ 1.56; 52.0 ≤ v1 ≤ 58.0;

[0013] 1.50 ≤ n2 ≤ 1.62; 68.0 ≤ v2 ≤ 73.0;

[0014] 1.52 ≤ n3 ≤ 1.55; 52.0 ≤ v3 ≤ 58.0;

[0015] 1.60 ≤ n4 ≤ 1.75; 19.0 ≤ v4 ≤ 22.0.

[0016] Optionally, the first convex-concave lens, the third biconvex lens, and the fourth convex-concave lens are all plastic aspherical lenses, and the second biconvex lens is a glass spherical lens.

[0017] Optionally, the diameter of the first convex-concave lens is D1, and the overall optical length of the day-night confocal lens is TTL, where D1 / TTL < 0.45.

[0018] Optionally, the image plane diameter IC of the day-night confocal lens satisfies: 6 mm ≤ IC ≤ 7.0 mm.

[0019] Optionally, the effective focal length of the day-night confocal lens is EFL, and the overall optical length of the day-night confocal lens is TTL, where TTL / EFL ≤ 5.5.

[0020] Optionally, the day-night confocal lens further includes a diaphragm, a protective glass, and a photosensitive chip in sequence from the object side to the image side. The diaphragm is disposed between the first convex-concave lens and the second biconvex lens, and the protective glass and the photosensitive chip are disposed on the side of the fourth convex-concave lens close to the image side.

[0021] Optionally, the protective glass is set as a flat filter, and the flat filter includes a first filter that can filter out infrared light and pass visible light, and a second filter that can pass both visible light and infrared light.

[0022] The present invention also provides an imaging device, and the imaging device includes the above-mentioned day-night confocal lens.

[0023] In the technical solution provided by the present invention, a first convex-concave lens with a negative optical power, a second biconvex lens with a positive optical power, a third biconvex lens with a positive optical power, and a fourth convex-concave lens with a negative optical power are sequentially arranged from the object side to the image side. By setting the first convex-concave lens with a negative optical power, it is beneficial to collect the light rays of the optical system and can effectively increase the monitoring field of view. By setting the second biconvex lens with a positive optical power, it undertakes a relatively large optical power of the system and corrects the axial aberration. By setting the third biconvex lens with a positive optical power, it changes the propagation direction of the light path. By setting the fourth convex-concave lens with a negative optical power, it corrects the residual aberration of the previous lenses and plays a role in correcting the field curvature. At the same time, by reasonably controlling the shape of the fourth convex-concave lens, the exit angle of the light rays at the last lens is reduced, and the CRA is reduced. By reasonably reducing the number of lenses, low cost and light weight can be achieved. This lens reasonably controls the light ray trend, makes the structure more compact while introducing more light rays, and the total length of the lens is controlled within 22.4 mm. By reasonably setting the optical power and shape of the four lenses, an FNO 1.6 large aperture can be achieved, and the resolution can reach 4M. High resolution is ensured under the large aperture. In terms of aperture, the aperture value F satisfies F = 1.6 and supports an image plane of 1 / 2.7 inches. The lens can also clearly image under low light conditions, and by reasonably controlling the focal ratio, the lens does not defocus under the environmental conditions of -40°C to +80°C, and can stably operate in two environments with large temperature differences during day and night, with a wide range of applications, so as to provide a low-cost, large-aperture, and small-sized day-night confocal lens that can be confocal day and night. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0025] Figure 1 It is a schematic structural diagram of the day-night confocal lens provided by the present invention;

[0026] Figure 2 is Figure 1 a schematic diagram of the chromatic aberration curve of the day-night confocal lens in

[0027] Figure 3 is Figure 1 a schematic diagram of the light fan of the day-night confocal lens in

[0028] Figure 4 is Figure 1 a schematic diagram of the field distortion / field curvature of the day-night confocal lens in

[0029] Figure 5 is Figure 1 the schematic diagram of the MTF (daytime state) of the day-night confocal lens in

[0030] Figure 6 is Figure 1 the schematic diagram of the MTF (night state) of the day-night confocal lens in

[0031] Explanation of the reference numerals in the attached drawings:

[0032] Label Name Label Name 1 First convex-concave lens 5 Diaphragm 2 Second biconvex lens 6 Protective glass 3 Third biconvex lens 7 Photosensitive chip 4 Fourth convex-concave lens 8 Flat filter

[0033] The realization, functional features and advantages of the object of the present invention will be further described with reference to the accompanying drawings in combination with the embodiments. Specific embodiments

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0036] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or the solution where A and B are satisfied simultaneously. In addition, the technical solutions between the embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0037] At present, with the continuous development of technology, the level of mold processing is getting higher and higher, the demand for lenses in the consumer market is increasing, and the requirements are gradually improving. At present, optical lenses with low cost, high pixels, large apertures, good infrared confocal performance, and the ability to adapt to environments with large temperature differences have become the pursuit goals of the consumer market. However, many similar products have a large number of lenses and a large proportion of glass used, which is not conducive to the large-scale promotion of the application range of fixed-focus lenses in the market.

[0038] To solve the above problems, the present invention provides a day-night confocal lens. Figures 1 to 6 This is a specific embodiment of the day-night confocal lens provided by the present invention.

[0039] Please refer to Figure 1 , the day-night confocal lens has an object side and an image side that are relatively arranged along the optical axis direction. The day-night confocal lens includes a first convex-concave lens 1 with a negative optical power, a second biconvex lens 2 with a positive optical power, a third biconvex lens 3 with a positive optical power, and a fourth convex-concave lens 4 with a negative optical power, which are arranged in sequence from the object side to the image side; the concave surface of the first convex-concave lens 1 faces the image side, the concave surface of the fourth convex-concave lens 4 faces the object side, the total optical length TTL of the day-night confocal lens is ≤ 22.4 mm, and the aperture value of the day-night confocal lens is F, and 1.6 ≤ F ≤ 2.0.

[0040] In the technical solution provided by the present invention, a first convex-concave lens 1 with a negative optical power, a second biconvex lens 2 with a positive optical power, a third biconvex lens 3 with a positive optical power, and a fourth convex-concave lens 4 with a negative optical power are sequentially arranged from the object side to the image side. By arranging the first convex-concave lens 1 with a negative optical power, it is beneficial to collect the light rays of the optical system and can effectively increase the monitoring field of view; by arranging the second biconvex lens 2 with a positive optical power, it undertakes a relatively large optical power of the system and corrects the axial aberration; by arranging the third biconvex lens 3 with a positive optical power, it changes the propagation direction of the light path; by arranging the fourth convex-concave lens with a negative optical power, it corrects the residual aberration of the previous lenses and plays a role in correcting the field curvature. At the same time, by reasonably controlling the shape of the fourth convex-concave lens 4, the exit angle of the light rays at the last lens is reduced, and the CRA is reduced. By reasonably reducing the number of lenses, low cost and light weight can be achieved. This lens reasonably controls the light path, introduces more light rays while making the structure more compact, and the total length of the lens is controlled within 22.4 mm. By reasonably setting the optical powers and shapes of the four lenses, an FNO 1.6 large aperture can be achieved, and the resolution can reach 4M, ensuring high resolution at a large aperture. In terms of aperture, the aperture value F satisfies 1.6 ≤ F ≤ 2.0 and supports a 1 / 2.7-inch image plane. The lens can also clearly image in low light, and by reasonably controlling the focal ratio, the lens does not defocus under the environmental conditions of -40°C to +80°C and can stably operate in two environments with large temperature differences during day and night, with a wide range of applications, so as to provide a low-cost, large-aperture, and small-sized day-night confocal lens that can be confocal day and night.

[0041] Specifically, in this embodiment, the focal length of the first convex-concave lens 1 is f1, the focal length of the second biconvex lens 2 is f2, the focal length of the third biconvex lens 3 is f3, and the focal length of the fourth convex-concave lens 4 is f4, where:

[0042] -6.2 < f1 < -5.0;

[0043] 7.4 < f2 < 8.5;

[0044] 4.8 < f3 < 5.8;

[0045] -9.0 < f4 < -7.8.

[0046] Through the mutual combination of different lenses and the reasonable distribution of their optical powers, the optical system has good performances such as low cost, large viewing angle, high pixel, and very good correction of thermal aberration.

[0047] Specifically, the refractive index of the first convex-concave lens 1 is n1, the dispersion coefficient is v1, the refractive index of the second biconvex lens 2 is n2, the dispersion coefficient is v2, the refractive index of the third biconvex lens 3 is n3, the dispersion coefficient is v3, the refractive index of the fourth convex-concave lens 4 is n4, and the dispersion coefficient is v4, where:

[0048] 1.54 ≤ n1 ≤ 1.56; 52.0 ≤ v1 ≤ 58.0;

[0049] 1.50 ≤ n2 ≤ 1.62; 68.0 ≤ v2 ≤ 73.0;

[0050] 1.52 ≤ n3 ≤ 1.55; 52.0 ≤ v3 ≤ 58.0;

[0051] 1.60 ≤ n4 ≤ 1.75; 19.0 ≤ v4 ≤ 22.0.

[0052] The dispersion coefficient is used to measure the degree of light dispersion of a transparent medium, and the Abbe number is an index used to represent the dispersion ability of a transparent medium. The larger the dispersion coefficient (Abbe number), the less obvious the dispersion, and the better the imaging quality of the lens. In this embodiment, the dispersion coefficients of the respective lenses are controlled at relatively high values, making the dispersion of the day-night confocal lens less obvious and the imaging quality of the lens good.

[0053] Specifically, since plastic lenses have strong impact resistance, low weight, and low cost, in order to further reduce costs and simultaneously meet the optical requirements of the lens, in this embodiment, the first convex-concave lens 1, the third biconvex lens 3, and the fourth convex-concave lens 4 are all plastic aspherical lenses. The setting of plastic lenses can reduce production costs. The characteristic of an aspherical lens is that the curvature continuously changes from the center of the lens to the periphery of the lens. Different from a spherical lens with a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has better curvature radius characteristics and has the advantages of improving distortion aberration and astigmatism aberration. After using an aspherical lens, it is possible to eliminate the aberration that appears during imaging as much as possible, thereby improving the imaging quality of the lens. In addition, by setting an aspherical lens, the chromatic aberration that appears during imaging of the lens can be eliminated, and the spherical aberration brought by the spherical lens in the collimation and focusing systems can also be corrected, improving the resolution quality of the optical system.

[0054] However, because the chemical properties of plastic materials are relatively unstable under the influence of environmental temperature, and their refractive index is weaker than that of a fully glass lens, resulting in a worse picture restoration degree than that of a fully glass lens. In order to ensure the stability of the video lens under temperature changes, in this embodiment, the second biconvex lens 2 is a glass spherical lens. Because glass lenses are not easily affected by thermal expansion and contraction and do not experience focus shift, glass lenses can well resist the problem of lens deformation due to heat and maintain high precision of the lens for a long time. The day-night confocal lens uses a glass-plastic hybrid material, which not only saves costs but also has strong impact resistance. Moreover, by reasonably matching plastic lenses and glass lenses, the problem that plastic aspherical lenses are prone to focus shift due to a large expansion coefficient under environmental conditions of -40°C to +80°C is overcome, making the working performance more stable.

[0055] Specifically, the diameter of the first convex-concave lens 1 is D1, and the total optical length of the day-night confocal lens is TTL. Among them, D1 / TTL < 0.45. When D1 and TTL satisfy the above relationship, it is possible to avoid an overly large lens aperture and meet the installation space requirements of the final product.

[0056] Specifically, in this embodiment, the image plane diameter IC of the day-night confocal lens satisfies: 6mm ≤ IC ≤ 7.0mm.

[0057] Specifically, the effective focal length of the day-night confocal lens is EFL, and the total optical length of the day-night confocal lens is TTL. Among them, TTL / EFL ≤ 5.5. By combining different lenses and reasonably distributing the optical power, it has good performance such as day-night confocal, large viewing angle, high pixel, and very good thermal aberration correction. It should be noted that the effective focal length EFL refers to the distance between the center vertex of the side of the first lens close to the object side and the imaging plane on the optical axis, and the total optical length TTL is the distance from the center vertex of the object side surface of the first lens to the imaging plane.

[0058] Further, please refer to Figure 1 , in this embodiment, the day-night confocal lens further includes a diaphragm 5, a protective glass 6, and a photosensitive chip 7 in sequence from the object side to the image side. The diaphragm 5 is disposed between the first convex-concave lens 1 and the second biconvex lens 2, and the protective glass 6 and the photosensitive chip 7 are disposed on the side of the fourth convex-concave lens 4 close to the image side. The diaphragm 5 can adjust the light flux according to the actual situation, thereby improving the imaging quality. The protective glass 6 can provide effective protection for the photosensitive chip 7. It can be understood that the surface of the photosensitive chip 7 facing the object side is the imaging plane.

[0059] It should be noted that the protective glass 6 can also be set as a filter. It can not only protect the photosensitive chip 7 but also filter out stray light. The filter can effectively filter out the stray light in the non-working wavelength band to reduce the optical noise and make it easier for the subsequent optoelectronic module processing part, thereby improving the imaging quality.

[0060] Specifically, in this embodiment, the protective glass 6 is set as a flat filter 8. The flat filter 8 includes a first filter that can filter out infrared light and pass visible light, and a second filter that can pass both visible light and infrared light. The first filter and the second filter can be switched through a specific mechanical structure. In the daytime state, the infrared light is filtered out and the visible light is passed through the first filter to achieve the daytime shooting function; in the night state, both visible light and infrared light can pass through the second filter to achieve the night shooting function.

[0061] Specifically, the imaging surface can be understood as the surface of the photosensitive chip 7 facing the object side, that is, it can be the surface of a camera element such as a CCD or a CMOS. It can be understood that the light carrying the information of the object to be photographed can sequentially pass through the first convex-concave lens 1, the second biconvex lens 2, the third biconvex lens 3, the fourth convex-concave lens 4 and finally form an image on the imaging surface.

[0062] Specifically, in this embodiment, the parameters of the day-night confocal lens are as follows:

[0063] The focal length f of the fixed-focus lens in this embodiment is 4.2 mm, the aperture value F is 1.6, the image plane diameter is 6.9 mm, and the diagonal field of view angle is 108°.

[0064] Specifically, in this embodiment, the refractive index, curvature radius, and thickness interval of the lens material are shown in Table 1 below:

[0065] Table 1

[0066]

[0067] Further, in this embodiment, the aspherical surface shape of the aspherical lens satisfies the following conditions:

[0068]

[0069] Where c is the curvature corresponding to the radius, y is the radial coordinate (whose unit is the same as the lens length unit), k is the conic quadratic coefficient (when the k coefficient is less than -1, the surface curve is a hyperbola; when the k coefficient is equal to -1, it is a parabola; when the k coefficient is between -1 and 0, it is an ellipse; when the k coefficient is equal to 0, it is a circle; when the k coefficient is greater than 0, it is an oblate circle), and the 4th-order term, 6th-order term, 8th-order term, 10th-order term, 12th-order term, 14th-order term, and 16th-order term respectively represent the high-order aspherical coefficients (please refer to Table 2 below). Through the above parameters, the shape dimensions of the aspherical surfaces on the object side and the image side of the lens can be set.

[0070] Table 2 Conic coefficients and aspherical coefficients corresponding to the aspherical lens:

[0071]

[0072]

[0073] Figure 2 It is a schematic diagram of the chromatic aberration curve of an embodiment of the day-night confocal lens. Figure 3 It is a schematic diagram of the light fan of an embodiment of the day-night confocal lens;

[0074] Figure 4Schematic diagram of field distortion / field curvature of an embodiment of the day-night confocal lens provided by the present invention. Among them, S and T in the figure respectively represent the aberrations corresponding to the sagittal image side and the meridional image side. The left side is the field curvature diagram, and the right side is the distortion diagram.

[0075] Figure 5 Schematic diagram of MTF (daytime state) of an embodiment of the day-night confocal lens provided by the present invention. Among them, the abscissa is the spatial frequency, and the ordinate is the contrast.

[0076] Figure 6 Schematic diagram of MTF (night state) of an embodiment of the day-night confocal lens provided by the present invention. Among them, the abscissa is the spatial frequency, and the ordinate is the contrast.

[0077] As can be seen from the above figures, the spherical aberration, field curvature, and distortion of the day-night confocal lens in this embodiment can all be well corrected.

[0078] In summary, the aperture value F of the day-night confocal lens satisfies 1.6 ≤ F ≤ 2.0, supports an image plane of 1 / 2.7 inches, can achieve a large aperture of FNO 1.6, and does not defocus under environmental conditions of -40°C to +80°C, and the total length of the lens is controlled within 22.4 mm.

[0079] In addition, the present invention also provides an imaging device. The imaging device can be an electronic device such as a photographic device, a monitoring device, a camera, etc. The imaging device includes the day-night confocal lens described in the above technical solution. The specific structure of this day-night confocal lens refers to the above embodiment. Since the day-night confocal lens of this day-night confocal lens adopts all the technical solutions of the above all embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated here one by one.

[0080] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made under the concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied to other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A day-night confocal lens, characterized in that, the day-night confocal lens has an object side and an image side that are oppositely arranged along the optical axis direction, and the day-night confocal lens includes a first convex-concave lens with a negative optical power, a second biconvex lens with a positive optical power, a third biconvex lens with a positive optical power, and a fourth convex-concave lens with a negative optical power arranged in sequence from the object side to the image side; the concave surface of the first convex-concave lens faces the image side, and the concave surface of the fourth convex-concave lens faces the object side; the overall optical length TTL of the day-night confocal lens is ≤ 22.4 mm, and the aperture value of the day-night confocal lens is F, and F = 1.6; the focal length of the first convex-concave lens is f1, the focal length of the second biconvex lens is f2, the focal length of the third biconvex lens is f3, and the focal length of the fourth convex-concave lens is f4, where: -6.2<f1<-5.0； 7.4<f2<8.5； 4.8<f3<5.8； -9.0<f4<-7.8。 2. The day-night confocal lens according to claim 1, characterized in that, the refractive index of the first convex-concave lens is n1, and the dispersion coefficient is v1, the refractive index of the second biconvex lens is n2, and the dispersion coefficient is v2, the refractive index of the third biconvex lens is n3, and the dispersion coefficient is v3, the refractive index of the fourth convex-concave lens is n4, and the dispersion coefficient is v4, where: 1.54 ≤ n1 ≤ 1.56; 52.0 ≤ v1 ≤ 58.0; 1.50 ≤ n2 ≤ 1.62; 68.0 ≤ v2 ≤ 73.0; 1.52 ≤ n3 ≤ 1.55; 52.0 ≤ v3 ≤ 58.0; 1.60 ≤ n4 ≤ 1.75; 19.0 ≤ v4 ≤ 22.

0.

3. The day-night confocal lens according to claim 1, characterized in that, the first convex-concave lens, the third biconvex lens and the fourth convex-concave lens are all plastic aspherical lenses, and the second biconvex lens is a glass spherical lens.

4. The day-night confocal lens according to claim 1, characterized in that, the diameter of the first convex-concave lens is D1, and the overall optical length of the day-night confocal lens is TTL, where D1 / TTL < 0.

45.

5. The day-night confocal lens according to claim 1, characterized in that, the image plane diameter IC of the day-night confocal lens satisfies: 6 mm ≤ IC ≤ 7.0 mm.

6. The day-night confocal lens according to claim 1, characterized in that, the effective focal length of the day-night confocal lens is EFL, and the overall optical length of the day-night confocal lens is TTL, where TTL / EFL ≤ 5.

5.

7. The day-night confocal lens according to claim 1, characterized in that, the day-night confocal lens further includes a diaphragm, a protective glass and a photosensitive chip in sequence from the object side to the image side, the diaphragm is arranged between the first convex-concave lens and the second biconvex lens, and the protective glass and the photosensitive chip are arranged on the side of the fourth convex-concave lens close to the image side.

8. The day-night confocal lens according to claim 7, characterized in that, the protective glass is set as a flat filter, and the flat filter includes a first filter that can filter out infrared light and pass visible light and a second filter that can pass both visible light and infrared light.

9. An imaging device, characterized in that, Comprising a day-night confocal lens according to any one of claims 1 to 8.

Images