A distortion-free high and low temperature confocal gate lens

Abstract

This invention discloses a distortion-free high- and low-temperature confocal gate lens, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially. The fifth and sixth lenses form a cemented lens group. The first lens is a convex-concave or biconcave aspherical lens with negative optical power; the second lens is a convex-concave aspherical lens with negative optical power; the third lens is a concave-convex or convex-concave aspherical lens with positive optical power; the fourth lens is a biconvex or concave-convex spherical lens with positive optical power; the fifth lens is a concave-convex or biconvex aspherical lens with positive optical power; the sixth lens is a biconcave or concave-convex aspherical lens with negative optical power; and the seventh lens is a convex-concave or concave-convex aspherical lens with positive optical power. The optical parameters are rationally set. This lens achieves the following characteristics: small size and lightweight design for large target surfaces; low distortion; clear imaging in low light; wide field of view; stable performance in high and low temperature environments; low cost; and wide applicability.

Description

Technical Field

[0001] This invention belongs to the field of optical lens technology, specifically relating to a distortion-free high and low temperature confocal gate lens. Background Technology

[0002] In the field of security cameras, the rapid development of access control cameras has led to a surge in demand. Access control cameras require a large shooting range and precise monitoring of object details during recording, placing higher demands on image quality. Therefore, as imaging systems become increasingly integrated and convenient, the matching lenses must be as small as possible in overall size while maintaining image quality to minimize space consumption. Furthermore, traditional access control cameras often produce images with severe distortion, making distortion correction difficult. A larger field of view also makes it more difficult to control the lens's dimensions, increasing design and manufacturing complexity. Therefore, it is essential to ensure that access control cameras can be miniaturized and distortion-free (in current technology, distortion less than 5% is considered distortion-free) while maintaining a large field of view. Summary of the Invention

[0003] The purpose of this invention is to address the above-mentioned problems by proposing a distortion-free high-low temperature confocal gate lens that meets the requirements of small size and lightweight design for large target surfaces, low distortion, clear imaging even in low light, wide field of view, high image quality, compact structure, and non-defocusing even under large temperature difference conditions. It also features stable performance, low cost, and wide applicability.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] This invention proposes a distortion-free high and low temperature confocal gate lens, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially from the object plane to the image plane. The fifth and sixth lenses form a cemented lens group, wherein:

[0006] The first lens is a convex-concave or biconcave aspherical lens with negative optical power;

[0007] The second lens is a convex-concave aspherical lens with negative optical power;

[0008] The third lens is a concave-convex or convex-concave aspherical lens with positive optical power;

[0009] The fourth lens is a biconvex or concave-convex spherical lens with positive optical power;

[0010] The fifth lens is a concave-convex or biconvex aspherical lens with positive optical power;

[0011] The sixth lens is a biconcave or concave-convex aspherical lens with negative optical power;

[0012] The seventh lens is a convex-concave or concave-convex aspherical lens with positive optical power;

[0013] And satisfy the following conditions:

[0014]

[0015]

[0016] Where f1 to f7 are the focal lengths of the first to seventh lenses, respectively, in mm; R 11 R 21 R 31 R 41 R 51 R 61 R 71 The following are the radii of curvature of the object-side mirror surfaces of the first to seventh lenses, in mm; R 12 R 22 R 32 R 42 R 52 R 62 R 72 The values ​​are the radii of curvature of the image-side mirrors of the first to seventh lenses, in mm; "-" indicates the negative direction.

[0017] Preferably, the first lens, the second lens, the third lens, the fifth lens, the sixth lens, and the seventh lens are all plastic lenses, and the fourth lens is a glass lens.

[0018] Preferably, the distortion-free high and low temperature confocal gate lens also meets the following conditions:

[0019] 0.1 <f1 / f2<0.15,1.85<|f3 / f4|<1.95,0.8<|f4 / f5|<0.85,-0.85<|f6 / f7|<-0.75。

[0020] Preferably, the distortion-free high and low temperature confocal gate lens also meets the following conditions:

[0021] <![CDATA[n d1 ]]> <![CDATA[n d2 ]]> <![CDATA[n d3 ]]> <![CDATA[n d4 ]]> <![CDATA[n d5 ]]> <![CDATA[n d6 ]]> <![CDATA[n d7 ]]> 1.536±5％ 1.536±5％ 1.661±5％ 1.603±5％ 1.536±5％ 1.639±5％ 1.535±5％ <![CDATA[v d1 ]]> <![CDATA[v d2 ]]> <![CDATA[v d3 ]]> <![CDATA[v d4 ]]> <![CDATA[v d5 ]]> <![CDATA[v d6 ]]> <![CDATA[v d7 ]]> 55.98±5％ 55.98±5％ 20.37±5％ 65.46±5％ 55.98±5％ 23.53±5％ 55.71±5％

[0022] Where, n d1 ~n d7 The refractive indices of the first to seventh lenses are shown in order, v d1 ~v d7 The Abbe numbers are listed in order from the first lens to the seventh lens.

[0023] Preferably, an aperture stop is provided between the third lens and the fourth lens.

[0024] Preferably, the distortion-free high and low temperature confocal gate lens also meets the following conditions:

[0025] 0.7 <SL / TTL<0.8,0.25<Bfl / TTL<0.39,

[0026] Where SL is the distance from the aperture stop to the image plane, in mm; Bfl is the back focal length, in mm; and TTL is the total optical length, in mm. The angle of incidence of the principal ray.

[0027] Preferably, the apertures of the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens and seventh lens are 4.684mm, 2.824mm, 2.438mm, 3.02mm, 3.452mm, 3.964mm and 4.985mm respectively.

[0028] Preferably, the distortion-free high and low temperature confocal gate lens has an effective focal length f of 3mm to 4mm, an F number of 2.0 to 2.1, and a total optical length TTL of less than 12mm.

[0029] Preferably, the mirror surfaces of the first lens, second lens, third lens, fifth lens, sixth lens, and seventh lens satisfy the following aspherical equation:

[0030]

[0031] In the formula, z is the sag, c is the curvature, y is the radial coordinate, k is the coefficient of the conic quadratic curve, and A i These are the coefficients of higher-order terms.

[0032] Preferably, the operating wavelength of the distortion-free high and low temperature confocal gate lens is 435nm~656nm and 830nm-870nm.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1) This access control lens balances aberrations through a combination of spherical and aspherical lenses, and reasonably sets the focal length and radius of curvature of each lens to correct various aberrations and improve edge image quality. The maximum target surface can be φ7mm, achieving high imaging quality. The fifth and sixth lenses are reasonably cemented together, which can effectively correct aberrations and meet the distortion-free requirements under a large field of view: optical distortion is less than 2% within a field of view of 98°, and the lens can achieve clear imaging in both visible light and infrared bands.

[0035] 2) The 1G6P glass-plastic hybrid structure is adopted, which reduces costs while ensuring image quality. The lens structure is compact by reasonably allocating optical power. The total optical length of the lens is within 12mm, and the head diameter and thread outer diameter are both within φ8mm, which meets the requirements of small size and lightweight.

[0036] 3) By reasonably setting the ratio of focal length, distance from aperture stop to image plane, back focal length, and total optical length, and by properly matching materials, the lens can remain in focus even in environments ranging from -40℃ to +85℃, resulting in more stable performance. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the distortion-free high and low temperature confocal gate lens of Embodiment 1 of the present invention;

[0038] Figure 2 This is the optical path diagram of the distortion-free high and low temperature confocal gate lens of Embodiment 1 of the present invention;

[0039] Figure 3 This is the MTF chart of Embodiment 1 of the present invention at a normal temperature of 20°C;

[0040] Figure 4 This is the MTF plot of Embodiment 1 of the present invention at a low temperature of -40°C.

[0041] Figure 5 This is the MTF diagram of Embodiment 1 of the present invention at a high temperature of 85°C;

[0042] Figure 6 This is the MTF diagram of Embodiment 1 of the present invention in the infrared band;

[0043] Figure 7 The field curvature and distortion diagrams are from Embodiment 1 of the present invention;

[0044] Figure 8 This is a schematic diagram of the distortion-free high and low temperature confocal gate lens of Embodiment 2 of the present invention;

[0045] Figure 9 This is the optical path diagram of the distortion-free high and low temperature confocal gate lens of Embodiment 2 of the present invention;

[0046] Figure 10 This is the MTF chart of Embodiment 2 of the present invention at a normal temperature of 20°C;

[0047] Figure 11 This is the MTF plot of Embodiment 2 of the present invention at a low temperature of -40°C.

[0048] Figure 12 This is the MTF diagram of Embodiment 2 of the present invention at a high temperature of 85°C;

[0049] Figure 13This is the MTF diagram of Embodiment 2 of the present invention in the infrared band;

[0050] Figure 14 This is a field curvature and distortion diagram of Embodiment 2 of the present invention.

[0051] Explanation of reference numerals in the attached diagram: L1, first lens; L2, second lens; L3, third lens; L4, fourth lens; L5, fifth lens; L6, sixth lens; L7, seventh lens; IR, filter; CG, protective glass; IMA, image plane. Detailed Implementation

[0052] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0053] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application.

[0054] like Figure 1-2 As shown, a distortion-free high and low temperature confocal gate lens includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7 arranged sequentially from the object plane to the image plane. The fifth lens L5 and the sixth lens L6 form a cemented lens group, wherein:

[0055] The first lens L1 is a convex-concave or biconcave aspherical lens with negative optical power;

[0056] The second lens L2 is a convex-concave aspherical lens with negative optical power;

[0057] The third lens L3 is a concave-convex or convex-concave aspherical lens with positive optical power;

[0058] The fourth lens, L4, is a biconvex or concave-convex spherical lens with positive optical power;

[0059] The fifth lens, L5, is a concave-convex or biconvex aspherical lens with positive optical power;

[0060] The sixth lens, L6, is a biconcave or concave-convex aspherical lens with negative optical power;

[0061] The seventh lens, L7, is a convex-concave or concave-convex aspherical lens with positive optical power;

[0062] And satisfy the following conditions:

[0063] <![CDATA[f1=-4.374±5%]]> <![CDATA[R 11 =8.60±5%]]> <![CDATA[R 12 =1.810±5%]]> <![CDATA[f2=-39.932±5%]]> <![CDATA[R 21 =2.36±5%]]> <![CDATA[R 22 =1.99±5%]]> <![CDATA[f3=10.231±5%]]> <![CDATA[R 31 =-21.15±5%]]> <![CDATA[R 32 =-5.22±5%]]> <![CDATA[f4=5.309±5%]]> <![CDATA[R 41 =32.65±5%]]> <![CDATA[R 42 =-3.51±5%]]> <![CDATA[f5=6.403±5%]]> <![CDATA[R 51 =-24.79±5%]]> <![CDATA[R 52 =-3.08±5%]]> <![CDATA[f6=-3.560±5%]]> <![CDATA[R 61 =-3.08±5%]]> <![CDATA[R 62 =9.48±5%]]> <![CDATA[f7=4.451±5%]]> <![CDATA[R 71 =2.336±5%]]> <![CDATA[R 72 =85.56±5%]]>

[0064] Where f1 to f7 are the focal lengths of the first lens L1 to the seventh lens L7, respectively, in mm; R 11 R 21 R 31 R 41 R 51 R 61 R 71 The radii of curvature of the object-side mirror surfaces of lenses L1 through L7, in mm, are as follows: R 12 R 22 R 32 R 42 R 52 R 62 R 72 The radii of curvature of the image-side mirrors of lenses L1 through L7 are in mm, respectively; "-" indicates the negative direction.

[0065] This access control camera consists of one spherical lens and six aspherical lenses. When light is incident, it passes sequentially through the first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, and seventh lens L7. The angle of incidence is adjusted to form an image; that is, the positive power lens converges the light, while the negative power lens diverges it. An IR filter and a protective glass CG are located between the sixth lens L6 and the image plane IMA. These can be arranged in any order, and the protective glass CG provides effective protection for the photosensitive chip located on the image plane IMA. The combination of spherical and aspherical lenses balances aberrations, and the focal length and radius of curvature of each lens are appropriately set to correct various aberrations, improving edge image quality. The maximum target area can be φ7mm, achieving high image quality. The properly configured cemented fifth and sixth lenses effectively correct aberrations, meeting the distortion-free requirement at a large field of view: optical distortion less than 2%, and enabling clear imaging in both visible and infrared bands. By rationally allocating optical power, the lens structure is made compact, with the total optical length of the lens within 12mm, and the head diameter and thread outer diameter within φ8mm and M8, respectively, meeting the requirements for small size and lightweight design.

[0066] In one embodiment, the first lens L1, the second lens L2, the third lens L3, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are all plastic lenses, while the fourth lens L4 is a glass lens. This access control camera consists of one spherical glass lens and six aspherical plastic lenses, employing a 1G6P glass-plastic hybrid structure, which reduces costs while ensuring image quality. It is easy to understand that the material of each lens can be adjusted according to actual needs.

[0067] In one embodiment, the distortion-free high and low temperature confocal gate lens also satisfies the following condition:

[0068] 0.1 <f1 / f2<0.15,1.85<|f3 / f4|<1.95,0.8<|f4 / f5|<0.85,-0.85<|f6 / f7|<-0.75。

[0069] The focal length of each lens can be set according to actual needs, and better image quality can be obtained when the above conditions are met.

[0070] In one embodiment, the distortion-free high and low temperature confocal gate lens also satisfies the following condition:

[0071] <![CDATA[n d1 ]]> <![CDATA[n d2 ]]> <![CDATA[n d3 ]]> <![CDATA[n d4 ]]> <![CDATA[n d5 ]]> <![CDATA[n d6 ]]> <![CDATA[n d7 ]]> 1.536±5％ 1.536±5％ 1.661±5％ 1.603±5％ 1.536±5％ 1.639±5％ 1.535±5％ <![CDATA[v d1 ]]> <![CDATA[v d2 ]]> <![CDATA[v d3 ]]> <![CDATA[v d4 ]]> <![CDATA[v d5 ]]> <![CDATA[v d6 ]]> <![CDATA[v d7 ]]> 55.98±5％ 55.98±5％ 20.37±5％ 65.46±5％ 55.98±5％ 23.53±5％ 55.71±5％

[0072] Where, n d1 ~n d7 The refractive indices of lenses L1 through L7 are, in order, v. d1 ~v d7 The Abbe numbers are, in order, those of the first lens L1 to the seventh lens L7.

[0073] In one embodiment, an aperture stop ST is also provided between the third lens L3 and the fourth lens L4 to facilitate adjustment of the light flux.

[0074] In one embodiment, the distortion-free high and low temperature confocal gate lens also satisfies the following condition:

[0075] 0.7 <SL / TTL<0.8,0.25<Bfl / TTL<0.39,

[0076] Where SL is the distance from the aperture stop ST to the image plane, in mm; Bfl is the back focal length, in mm; and TTL is the total optical length, in mm. The angle of incidence of the principal ray.

[0077] When the access control lens satisfies 0.7 < SL / TTL < 0.8, it helps to ensure a large light aperture at a small F-number (such as 2.0 - 2.1) and meet the resolution requirements. When 0.25 < Bfl / TTL < 0.39, the door lens further has a small distortion under the conditions of meeting a small F-number and a compact structure.

[0078] In one embodiment, the apertures of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are 4.684mm, 2.824mm, 2.438mm, 3.02mm, 3.452mm, 3.964mm, and 4.985mm in sequence.

[0079] Among them, the aperture of the first lens L1, 4.684mm, can realize within the head of the access control lens of φ8.0mm. For example, an aperture stop ST is provided between the third lens L3 and the fourth lens L4. The apertures of the first lens L1, the second lens L2, and the third lens L3 decrease in sequence along the optical axis direction, achieving miniaturization of the overall structure while reducing costs; the apertures of the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 increase in sequence along the optical axis direction. The aperture of the seventh lens L7, 4.985mm, meets the requirement of the outer diameter M8 of the lens thread. The structure is made compact with a plastic material, reducing tolerance sensitivity and cost to ensure small front and rear apertures in the case of a large target surface. The plastic aspheric surface承担主要光焦度减少成本,方便装配,降低制造难度并提升良率。(原文本此处表述有误,已按正确理解翻译)

[0080] In one embodiment, the effective focal length f of the distortion-free high and low temperature confocal access control lens is 3mm to 4mm, the F-number is 2.0 to 2.1, and the optical total length TTL is less than 12mm.

[0081] In one embodiment, the mirror surfaces of the first lens L1, the second lens L2, the third lens L3, the fifth lens L5, the sixth lens L6, and the seventh lens L7 satisfy the following aspheric equation:

[0082]

[0083] In the formula, z is the sag height, c is the curvature, y is the radial coordinate, k is the conic coefficient, and A i is the high-order term coefficient.

[0084] In one embodiment, the working wavelength band of the distortion-free high and low temperature confocal access control lens is 435nm to 656nm and 830nm - 870nm. Clear imaging can be achieved under visible light and infrared light.

[0085] The following is a detailed description through specific embodiments.

[0086] Embodiment 1:

[0087] like Figure 1 As shown, in this embodiment, the first lens L1 is a convex-concave aspherical lens, the second lens L2 is a convex-concave aspherical lens, the third lens L3 is a concave-convex aspherical lens, the fourth lens L4 is a biconvex spherical lens, the fifth lens L5 is a concave-convex aspherical lens, the sixth lens L6 is a biconcave aspherical lens, and the seventh lens L7 is a convex-concave aspherical lens. Figure 1 The leftmost vertical line represents only a virtual surface, not a specific structure. The planes represented by the other vertical lines between lenses (such as between the second lens L2 and the third lens L3, and between the sixth lens L6 and the seventh lens L7) are also virtual surfaces that act as light-blocking plates. A filter IR and a protective glass CG are also provided between the sixth lens L6 and the image plane IMA. The two can be arranged in any order. In this embodiment, the filter IR is set close to the image plane IMA, and the filter IR and the protective glass CG are made of the same material. Figure 3-6 The vertical axis represents the OTF modulus, and the horizontal axis represents the spatial frequency in cycles per mm. Figure 3 , 4 and Figure 5 The MTF charts for room temperature (20℃), low temperature (-40℃), and high temperature (85℃) are all in the visible light band; while Figure 6 This is the MTF plot at room temperature (20°C) in the infrared band. Figure 7 The left image is the field curvature diagram, and the right image is the distortion diagram.

[0088] The optical parameters of each lens in this embodiment are shown in Table 1, and the aspherical coefficients are shown in Table 2.

[0089] Table 1

[0090]

[0091] Table 2

[0092] k <![CDATA[A2]]> <![CDATA[A3]]> <![CDATA[A4]]> <![CDATA[A5]]> <![CDATA[A6]]> <![CDATA[A7]]> <![CDATA[A8]]> R11 -27.5867 4.59E-02 -7.00E-02 1.59E-03 1.19E-04 -1.05E-04 1.71E-05 -9.92E-07 R12 -0.07262 2.07E-02 9.96E-02 -6.30E-03 3.38E-03 1.12E-03 -1.04E-03 -6.52E-05 R21 -15.3637 4.98E-02 -1.18E-01 2.04E-01 -2.47E-02 1.53E-02 -1.52E-03 7.19E-05 R22 -4.05166 1.63E-03 -8.73E-03 -1.30E-01 2.45E-01 -2.34E-01 1.12E-01 -2.12E-02 R31 88.01827 -1.37E-02 1.90E-02 -7.93E-02 3.47E-02 9.25E-03 4.43E-02 1.08E-02 R32 -35.838 -1.48E-02 9.28E-03 1.70E-02 -3.77E-02 2.99E-02 -1.19E-02 1.72E-03 R51 81.13388 -2.03E-04 5.95E-03 2.93E-03 -3.44E-03 8.62E-03 -3.84E-04 3.53E-05 R52 0.864532 -3.53E-01 2.13E-01 -1.91E-01 6.58E-02 -2.76E-02 4.34E-03 -2.80E-04 R61 0.864532 -1.53E-01 1.03E-02 -1.91E-01 6.58E-02 -2.76E-02 4.34E-03 -2.80E-04 R62 -93.7358 -2.32E-02 -1.84E-02 -3.56E-02 1.42E-02 -3.38E-03 7.42E-04 -2.45E-05 R71 -0.21314 -4.03E-02 1.32E-02 -8.61E-03 1.96E-03 -2.73E-04 2.19E-05 -8.27E-07 R72 98.42977 1.77E-05 -4.76E-04 3.33E-04 -3.01E-04 -3.76E-05 -1.10E-05 5.33E-07

[0093] The object-side mirror surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are respectively denoted as R11, R21, R31, R41, R51, R61, and R71; the image-side mirror surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are respectively denoted as R12, R22, R32, R42, R52, R62, and R72.

[0094] Based on the above data, by Figure 3 ,4 As shown in Figure 5, the lens did not exhibit severe defocusing in its MTF curves under extreme conditions including ambient temperature (20℃), low temperature (-40℃), and high temperature (85℃); Figure 6 As shown, this lens can also produce clear images when focusing in the infrared band; generally, a lens with distortion of less than 5% can be called a distortion-free lens. Figure 7 As shown, this lens can meet the requirements of distortion-free imaging in a large market, with a maximum optical distortion of less than 1.9%. The lens used effectively improves the image quality and significantly shortens the overall optical length of the lens, with a TTL of 12mm, which effectively saves assembly space and makes it more compact. Furthermore, the F-number of 2.0 ensures clear imaging in low light, and the target surface can reach φ7mm, resulting in better resolution.

[0095] Example 2:

[0096] like Figure 8 As shown, in this embodiment, the first lens L1 is a biconcave aspherical lens, the second lens L2 is a convex-concave aspherical lens, the third lens L3 is a convex-concave aspherical lens, the fourth lens L4 is a concave-convex spherical lens, the fifth lens L5 is a biconvex aspherical lens, the sixth lens L6 is a concave-convex aspherical lens, and the seventh lens L7 is a concave-convex aspherical lens. Figure 8 The leftmost vertical line represents only a virtual surface, not a specific structure. The planes represented by the other vertical lines between lenses (such as between the second lens L2 and the third lens L3, and between the sixth lens L4 and the seventh lens L5) are also virtual surfaces that act as light-blocking plates. A filter IR and a protective glass CG are also provided between the sixth lens L6 and the image plane IMA. The two can be arranged in any order. In this embodiment, the filter IR is set close to the image plane IMA, and the filter IR and the protective glass CG are made of the same material. Figure 10-13 The vertical axis represents the OTF modulus, and the horizontal axis represents the spatial frequency in cycles per mm. Figure 10 , 11 and Figure 12 The MTF charts for room temperature (20℃), low temperature (-40℃), and high temperature (85℃) are all in the visible light band; while Figure 13 This is the MTF plot at room temperature (20°C) in the infrared band. Figure 14 The left image is the field curvature diagram, and the right image is the distortion diagram.

[0097] The optical parameters of each lens in this embodiment are shown in Table 3, and the aspherical coefficients are shown in Table 4.

[0098] Table 3

[0099]

[0100] Table 4

[0101]

[0102]

[0103] The object-side mirror surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are respectively denoted as R11, R21, R31, R41, R51, R61, and R71; the image-side mirror surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are respectively denoted as R12, R22, R32, R42, R52, R62, and R72.

[0104] Based on the above data, by Figure 10 , 11 As shown in Figure 12, the lens did not exhibit severe defocusing in its MTF curves under extreme conditions including ambient temperature (20℃), low temperature (-40℃), and high temperature (85℃); Figure 13 As shown, this lens can also produce clear images when focusing in the infrared band; generally, a lens with distortion of less than 5% can be called a distortion-free lens. Figure 14 As shown, this lens can meet the requirements of distortion-free imaging in a large market, with a maximum optical distortion of less than 1.9%. The lens used effectively improves the image quality and significantly shortens the overall optical length of the lens, with a TTL of 12mm, which effectively saves assembly space and makes it more compact. Furthermore, the F-number of 2.0 ensures clear imaging in low light, and the target surface can reach φ7mm, resulting in better resolution.

[0105] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0106] The embodiments described above are merely specific and detailed examples of the embodiments described in this application, and should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this patent application should be determined by the appended claims.

Claims

1. A distortion-free high and low temperature confocal gate lens, characterized in that: The distortion-free high and low temperature confocal gated lens includes a first lens (L1), a second lens (L2), a third lens (L3), a fourth lens (L4), a fifth lens (L5), a sixth lens (L6), and a seventh lens (L7) arranged sequentially from the object plane to the image plane. The fifth lens (L5) and the sixth lens (L6) form a cemented lens group. The distortion-free high and low temperature confocal gated lens has seven lenses with optical power, of which: The first lens (L1) is a convex-concave aspherical lens with negative optical power; The second lens (L2) is a convex-concave aspherical lens with negative optical power; The third lens (L3) is a concave-convex aspherical lens with positive optical power; The fourth lens (L4) is a biconvex spherical lens with positive optical power; The fifth lens (L5) is a concave-convex aspherical lens with positive optical power; The sixth lens (L6) is a biconcave aspherical lens with negative optical power; The seventh lens (L7) is a convex-concave aspherical lens with positive optical power; And satisfy the following conditions: Where f1~f7 are the focal lengths of the first lens (L1) to the seventh lens (L7), respectively, in mm; R 11 R 21 R 31 R 41 R 51 R 61 R 71 The radii of curvature of the object-side mirror surfaces of the first lens (L1) to the seventh lens (L7), in mm, are as follows: R 12 R 22 R 32 R 42 R 52 R 62 R 72 The curvature radii of the image-side mirrors of the first lens (L1) to the seventh lens (L7) are in mm, respectively; "-" indicates the negative direction.

2. The distortion-free high and low temperature confocal gate lens as described in claim 1, characterized in that: The first lens (L1), the second lens (L2), the third lens (L3), the fifth lens (L5), the sixth lens (L6), and the seventh lens (L7) are all plastic lenses, and the fourth lens (L4) is a glass lens.

3. The distortion-free high and low temperature confocal gate lens as described in claim 1, characterized in that: The distortion-free high and low temperature confocal gate lens also meets the following conditions: 1.85<|f3 / f4|<1.95, 0.8<|f4 / f5|<0.

85.

4. The distortion-free high and low temperature confocal gate lens as described in claim 1, characterized in that: The distortion-free high and low temperature confocal gate lens also meets the following conditions: Where, n d1 ~ n d7 The refractive indices of the first lens (L1) to the seventh lens (L7) are, in order, v d1 ~ v d7 The Abbe numbers are, in order, the first lens (L1) to the seventh lens (L7).

5. The distortion-free high and low temperature confocal gate lens as described in claim 1, characterized in that: An aperture stop (ST) is also provided between the third lens (L3) and the fourth lens (L4).

6. The distortion-free high and low temperature confocal gate lens as described in claim 5, characterized in that: The distortion-free high and low temperature confocal gate lens also meets the following conditions: 0.7 <SL / TTL<0.8,0.25<Bfl / TTL<0.39,17.5°<φ<19° Wherein, SL is the distance from the aperture stop (ST) to the image plane, in mm; Bfl is the back focal length, in mm; TTL is the total optical length, in mm; and φ is the incident angle of the principal ray.

7. The distortion-free high and low temperature confocal gate lens as described in claim 5, characterized in that: The apertures of the first lens (L1), the second lens (L2), the third lens (L3), the fourth lens (L4), the fifth lens (L5), the sixth lens (L6), and the seventh lens (L7) are 4.684mm, 2.824mm, 2.438mm, 3.02mm, 3.452mm, 3.964mm, and 4.985mm, respectively.

8. The distortion-free high and low temperature confocal gate lens as described in claim 1, characterized in that: The distortion-free high and low temperature confocal gate lens has an effective focal length f of 3mm to 4mm and an F number of 2.0 to 2.

1.

9. The distortion-free high and low temperature confocal gate lens as described in claim 1, characterized in that: The object-side and image-side mirrors of the first lens (L1), the second lens (L2), the third lens (L3), the fifth lens (L5), the sixth lens (L6), and the seventh lens (L7) satisfy the following aspherical equation: ; In the formula, z is the sag, c is the curvature, y is the radial coordinate, k is the coefficient of the conic quadratic curve, and A i These are the coefficients of higher-order terms.

10. The distortion-free high and low temperature confocal gate lens as described in claim 1, characterized in that: The distortion-free high and low temperature confocal gate lens operates in the wavelength range of 435nm~656nm and 830nm-870nm.

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