A surveillance lens with small size, large light transmission and low distortion

Abstract

The present invention discloses a small-volume, high-light transmission and low-distortion surveillance lens, which comprises, from the object side to the image side along the optical axis, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, an aperture C, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11 and a twelfth lens L12, wherein the fourth lens L4 and the fifth lens L5 are closely connected to form a first cemented lens group; the eighth lens L8 and the ninth lens L9 are closely connected to form a second cemented lens group; the eleventh lens L11 and the twelfth lens L12 are closely connected to form a third cemented lens group; the first lens L1 to the sixth lens L6 form a front lens group; the seventh lens L7 to the twelfth lens L12 form a rear lens group. The surveillance lens of the present invention has the performance of small volume, low distortion, high light transmission, large target surface and high resolution.

Description

Technical Field

[0001] The invention belongs to the technical field of optical lenses, and in particular relates to a monitoring lens with small volume, large light transmission and low distortion. Background Art

[0002] Surveillance cameras play an important role in intelligent transportation systems and determine the accuracy of information obtained.

[0003] Due to the special application environment, some performance requirements of surveillance lenses need to be different from those of ordinary lenses, such as smaller size, lower imaging distortion, larger imaging target area and higher resolution.

[0004] Existing surveillance lenses are difficult to fully meet the above requirements. The market needs a surveillance lens with small size, large light transmission, low distortion, large target area and high resolution.

[0005] Therefore, inventing a surveillance camera that meets the above requirements has become a more urgent need. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a surveillance lens with small volume, large light transmission and low distortion, so that it has the performance of miniaturization, low distortion, large light transmission, large target area and high resolution.

[0007] To achieve the above object, the present invention provides the following technical solution: a small-volume, high-light transmission and low-distortion surveillance lens, comprising, in order from the object side to the image side along the optical axis: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, an aperture C, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11 and a twelfth lens L12,

[0008] The first lens L1, the fifth lens L5, the sixth lens L6, the eighth lens L8, the tenth lens L10 and the eleventh lens L11 have positive refractive power; the second lens L2, the third lens L3, the fourth lens L4, the seventh lens L7, the ninth lens L9 and the twelfth lens L12 have negative refractive power;

[0009] Among them, the fourth lens L4 and the fifth lens L5 are closely connected to form a first cemented lens group; the eighth lens L8 and the ninth lens L9 are closely connected to form a second cemented lens group; the eleventh lens L11 and the twelfth lens L12 are closely connected to form a third cemented lens group;

[0010] The first lens L1 to the sixth lens L6 constitute a front lens group; the seventh lens L7 to the twelfth lens L12 constitute a rear lens group;

[0011] The surveillance camera meets the following conditions: 0.05≤|(f G1 ×f / (fG2 +f G3 ))×tan(FOV / 4)|≤0.8, where f G1 f is the effective focal length of the first cemented lens group; G2 is the effective focal length of the second cemented lens group; f G3 is the effective focal length of the third cemented lens group; FOV is the maximum field of view of the monitoring lens.

[0012] As a specific implementation, in the monitoring lens,

[0013] The first lens L1 is a biconvex positive lens or a meniscus positive lens with the convex surface facing the object;

[0014] The second lens L2 is a negative meniscus lens with its convex surface facing the object;

[0015] The third lens L3 is a double concave negative lens;

[0016] The fourth lens L4 is a negative meniscus lens with a convex surface facing the image side;

[0017] The fifth lens L5 is a positive meniscus lens with a convex surface facing the image side;

[0018] The sixth lens L6 is a biconvex positive lens;

[0019] The seventh lens L7 is a negative meniscus lens with a convex surface facing the object;

[0020] The eighth lens L8 is a biconvex positive lens;

[0021] The ninth lens L9 is a double concave negative lens;

[0022] The tenth lens L10 is a biconvex positive lens or a meniscus positive lens with the convex surface facing the image side;

[0023] The eleventh lens L11 is a biconvex positive lens;

[0024] The twelfth lens L12 is a biconcave negative lens.

[0025] As a specific implementation, the monitoring lens satisfies the following condition: (FOV×f) / IH≤112, where FOV is the maximum field of view of the monitoring lens, f is the effective focal length of the monitoring lens, and IH is the maximum image plane height of the monitoring lens.

[0026] As a specific implementation method, the monitoring camera satisfies the following condition: u1 / f|≤2.4,|f u2 / f|≥2, where f u1 is the effective focal length of the front lens group, f u2 is the effective focal length of the rear lens group, and f is the effective focal length of the monitoring lens.

[0027] As a specific implementation method, the monitoring lens satisfies the following condition: SD max / TTL≤0.4, where SD max is the clear aperture of the largest lens in the monitoring lens, and TTL is the total optical length of the monitoring lens, that is, the distance from the center of the object side of the first lens L1 to the imaging surface.

[0028] As a specific implementation, the monitoring lens satisfies the following condition: FOV / (D×TTL)≥0.01, wherein FOV is the maximum field of view of the monitoring lens, D is the aperture size of the monitoring lens head, and TTL is the total optical length of the monitoring lens.

[0029] As a specific implementation manner, the monitoring lens satisfies the following conditional formula: IH / FNO≥5.2, wherein IH is the maximum image plane height of the monitoring lens, and FNO is the aperture value of the monitoring lens.

[0030] As a specific implementation, the monitoring lens satisfies the following condition: f / IH≥2.5, where f is the effective focal length of the monitoring lens, and IH is the maximum image plane height of the monitoring lens.

[0031] As a specific implementation, the monitoring lens satisfies the following condition: TTL≤102 mm, where TTL is the total optical length of the monitoring lens.

[0032] Compared with the prior art, the present invention provides a surveillance lens with small volume, large light transmission and low distortion, which has the following beneficial effects:

[0033] 1) The present invention achieves the purpose of low distortion by reasonably controlling the optical power of the front and rear lens groups;

[0034] 2) The present invention realizes the high resolution requirement of the optical system by reasonably allocating the positions of lenses with different optical powers;

[0035] 3) The present invention realizes high-resolution imaging of the optical system by reasonably allocating the optical power of the front group and the rear group;

[0036] 4) The present invention reasonably controls the optical power of the sixth lens L6 and the seventh lens L7 so that TTL is ≤ 102 mm to meet the miniaturization requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The optical path diagram of the surveillance lens with small volume, large light transmission and low distortion in Example 1;

[0038] Figure 2 The MTF curve of the small-volume, high-light-throughput, and low-distortion surveillance lens in the visible light band in Example 1;

[0039] Figure 3 This is a field curvature distortion diagram of the small-volume, high-light-throughput, and low-distortion surveillance lens in Example 1;

[0040] Figure 4 This is the optical path diagram of the surveillance lens with small volume, large light throughput and low distortion in Example 2;

[0041] Figure 5 The MTF curve of the visible light band of the small-volume, high-light transmission and low-distortion surveillance lens in Example 2;

[0042] Figure 6 This is a field curvature distortion diagram of the small-volume, high-light-throughput, and low-distortion surveillance lens in Example 2;

[0043] Figure 7 This is the optical path diagram of the surveillance lens with small volume, large light throughput and low distortion in Example 3;

[0044] Figure 8 The MTF curve of the visible light band of the small-volume, high-light transmission and low-distortion surveillance lens in Example 3;

[0045] Fig. 9 This is a field curvature distortion diagram of the surveillance lens with small volume, large light transmission and low distortion in Example 3. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The present invention provides a surveillance lens with small size, large light transmission and low distortion, which comprises, in order from the object side to the image side along the optical axis: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, an aperture C, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11 and a twelfth lens L12.

[0048] Among them, the first lens L1, the fifth lens L5, the sixth lens L6, the eighth lens L8, the tenth lens L10, and the eleventh lens L11 have positive refractive power; the second lens L2, the third lens L3, the fourth lens L4, the seventh lens L7, the ninth lens L9, and the twelfth lens L12 have negative refractive power;

[0049] The fourth lens L4 and the fifth lens L5 are closely connected to form a first cemented lens group; the eighth lens L8 and the ninth lens L9 are closely connected to form a second cemented lens group; the eleventh lens L11 and the twelfth lens L12 are closely connected to form a third cemented lens group; the first lens L1 to the sixth lens L6 constitute a front lens group; the seventh lens L7 to the twelfth lens L12 constitute a rear lens group.

[0050] Here, the aperture of the first lens L1 is not less than 35 mm, which is conducive to collecting more light and focusing the light entering the lens.

[0051] The second lens L2 can perform primary correction on the light collected by the first lens L1 and transfer it to the rear optical system.

[0052] The third lens L3 can perform secondary correction on the light collected by the second lens L2.

[0053] The fourth lens L4 and the fifth lens L5 are bonded together to form a bonded component, which corrects the light corrected by the third lens L3 and balances the distortion produced by the lens. At the same time, the fourth lens L4 and the fifth lens L5 are both made of glass lenses, which further enhances the stability of the lens group.

[0054] The sixth lens L6 can collect the light corrected by the cemented lens and transmit it to the rear optical system through the aperture.

[0055] The aperture C is placed between the sixth lens L6 and the seventh lens L7 to control the imaging quality and the performance of the optical system by limiting the propagation range and direction of the light beam.

[0056] The seventh lens L7 can collect and focus the light entering through the aperture C and transition it to the rear optical system.

[0057] The eighth lens L8 and the ninth lens L9 are glued together to form the second group of glued parts, which perform secondary correction on the light corrected by the front optical system to balance the distortion produced by the lens. The eighth lens L8 and the ninth lens L9 are also made of glass lenses to further enhance the stability of the lens group.

[0058] The tenth lens L10 can transfer the light corrected by the second group of cemented components to the rear imaging system.

[0059] The eleventh lens L11 and the twelfth lens L12 are cemented to form a third cemented component, which is used to eliminate or balance the distortion produced by the lens and reduce the tolerance sensitivity. The eleventh lens L11 and the twelfth lens L12 are also glass lenses, which can effectively improve the stability and durability of the lens group.

[0060] Other lenses in the following embodiments may also be made of glass. Example 1

[0061] In the optical system of this example, the first lens L1 is a biconvex positive lens; the second lens L2 is a meniscus negative lens with the convex surface facing the object; the third lens L3 is a biconcave negative lens; the fourth lens L4 is a meniscus negative lens with the convex surface facing the image; the fifth lens L5 is a meniscus positive lens with the convex surface facing the image; the sixth lens L6 is a biconvex positive lens; the seventh lens L7 is a meniscus negative lens with the convex surface facing the object; the eighth lens L8 is a biconvex positive lens; the ninth lens L9 is a biconcave negative lens; the tenth lens L10 is a biconvex positive lens; the eleventh lens L11 is a biconvex positive lens; and the twelfth lens L12 is a biconcave negative lens. The fourth lens L4 and the fifth lens L5, the eighth lens L8 and the ninth lens L9, and the eleventh lens L11 and the twelfth lens L12 are glued together respectively. The optical path diagram of the monitoring lens is shown in Figure 1 shown.

[0062] See Table 1, which lists the relevant parameters of each lens in this example, including the radius of curvature, thickness, refractive index of the material, and Abbe number:

[0063] Table 1

[0064]

[0065] Infinity means infinity.

[0066] In this example, the air distance from the first lens L1 to the second lens L2 is 2.5300 mm; the air distance from the second lens L2 to the third lens L3 is 11.6240 mm; the air distance from the third lens L3 to the fourth lens L4 is 1.3553 mm; the air distance from the fifth lens L5 to the sixth lens L6 is 1.0972 mm; the air distance from the sixth lens L6 to the aperture C is 1.4821 mm; the air distance from the aperture C to the seventh lens L7 is 4.3401 mm; the air distance from the seventh lens L7 to the eighth lens L8 is 2.7187 mm; the air distance from the ninth lens L9 to the tenth lens L10 is 3.3819 mm; the air distance from the tenth lens L10 to the eleventh lens L11 is 0.1420 mm; and the air distance from the twelfth lens L12 to the image plane IMG is 13.4093 mm.

[0067] The technical indicators achieved by the optical system in this example are as follows:

[0068] 1) Maximum field of view of the surveillance camera: FOV = 43.2°;

[0069] 2) Effective focal length of the front lens: f u1 =46.6833mm;

[0070] 3) Effective focal length of the rear lens: f u2 =40.7276mm;

[0071] 4) Effective focal length of the first cemented lens group: f G1 =46.23mm;

[0072] 5) Effective focal length of the second lens group: f G2 =-286.15 mm;

[0073] 6) Effective focal length of the third cemented lens group; f G3 =49.32mm;

[0074] 7) Effective focal length of surveillance lens: f=20.3517mm;

[0075] 8) Maximum image height of the monitoring lens: IH = 7.9040mm;

[0076] 9) Aperture value of monitoring lens: FNO=1.5124;

[0077] 10) Monitoring lens head aperture size: D = 37.7687mm;

[0078] 11) The largest aperture of the surveillance lens: SD max =37.7687mm;

[0079] 12) Total optical length of the monitoring lens: TTL = 101.0110mm.

[0080] Then we get:|(f G1 ×f / (f G2 +f G3 ))×tan(FOV / 4)|=0.7578; (FOV×f) / IH=111.2340;|f u1 / f|=2.2938;|f u2 / f|=2.0012; SD max / TTL=0.37; FOV / (D×TTL)=0.0113; IH / FNO=5.2262; f / IH=2.5749.

[0081] Here, by properly distributing the optical power of the glued lens, i.e. |(f G1 ×f / (f G2 +f G3 ))×tan(FOV / 4)|, to achieve the requirement of low distortion.

[0082] By rationally combining different lenses, that is, requiring (FOV×f) / IH≤112, the propagation light in the optical system is continuously corrected to achieve the low distortion requirement.

[0083] By reasonably allocating the proportion of the front and rear group focal lengths to the focal length of the entire lens, that is, requiring |f u1 / f|≤2.4,|f u2 / f|≥2, to meet the high resolution requirement of the system.

[0084] By limited SD max / TTL≤0.4, FOV / (D×TTL)≥0.01, which realizes the miniaturization of the lens. By limiting IH / FNO≥5.2, the demand for a large target surface is met, and by limiting f / IH≥2.5, the demand for a large light flux is met.

[0085] The final imaging effect of the lens in this example is achieved through Figure 2 The MTF graph of the lens shows that the MTF curves in each field of view all drop gently and have good consistency. As can be seen from the graph, the MTF value of the edge field of view at the spatial frequency of 80pl / mm is greater than 0.48, which means that the lens has good imaging effect and resolution in the full field of view. Figure 3 This is the field curvature distortion diagram of the lens of this embodiment. It can be seen that the distortion of the lens does not exceed 2%. Example 2

[0086] In this example, in the optical system, the first lens L1 is a double convex positive lens; the second lens L2 is a meniscus negative lens with the convex surface facing the object side; the third lens L3 is a double concave negative lens; the fourth lens L4 is a meniscus negative lens with the convex surface facing the image side; the fifth lens L5 is a meniscus positive lens with the convex surface facing the image side; the sixth lens L6 is a double convex positive lens; the seventh lens L7 is a meniscus negative lens with the convex surface facing the object side; the eighth lens L8 is a double convex positive lens; the ninth lens L9 is a double concave negative lens; the tenth lens L10 is a meniscus positive lens with the convex surface facing the image side; the eleventh lens L11 is a double convex positive lens; and the twelfth lens L12 is a double concave negative lens. The fourth lens L4 is glued to the fifth lens L5, the eighth lens L8 is glued to the ninth lens L9, and the eleventh lens L11 is glued to the twelfth lens L12. The optical path diagram of the monitoring lens is shown in Figure 4 shown.

[0087] See Table 2, which lists the relevant parameters of each lens in this example, including the radius of curvature, thickness, refractive index of the material, and Abbe number:

[0088] Table 2

[0089]

[0090] In this example, the air distance from the first lens L1 to the second lens L2 is 1.8875 mm; the air distance from the second lens L2 to the third lens L3 is 11.5211 mm; the air distance from the third lens L3 to the fourth lens L4 is 1.3672 mm; the air distance from the fifth lens L5 to the sixth lens L6 is 1.0913 mm; the air distance from the sixth lens L6 to the aperture C is 1.5018 mm; the air distance from the aperture C to the seventh lens L7 is 4.3645 mm; the air distance from the seventh lens L7 to the eighth lens L8 is 2.8060 mm; the air distance from the ninth lens L9 to the tenth lens L10 is 3.3802 mm; the air distance from the tenth lens L10 to the eleventh lens L11 is 0.1450 mm; and the air distance from the twelfth lens L12 to the image plane IMG is 13.6375 mm.

[0091] The technical indicators achieved by the optical system in this example are as follows:

[0092] 1) Maximum field of view of the surveillance camera: FOV = 43.2°;

[0093] 2) Effective focal length of the front lens: f u1 =46.8103mm;

[0094] 3) Effective focal length of the rear lens: f u2 =40.8371mm;

[0095] 4) Effective focal length of the first cemented lens group: f G1 =46.23mm;

[0096] 5) Effective focal length of the second lens group: f G2 =-321.32mm;

[0097] 6) Effective focal length of the third cemented lens group; f G3 =47.70mm;

[0098] 7) Effective focal length of surveillance lens: f=20.3976mm;

[0099] 8) Maximum image height of the monitoring lens: IH = 7.9040mm;

[0100] 9) Aperture value of monitoring lens: FNO = 1.5123;

[0101] 10) Monitoring lens head aperture size: D = 37.2135mm;

[0102] 11) The largest aperture of the surveillance lens: SD max =37.2135mm;

[0103] 12) Total optical length of the monitoring lens: TTL = 101.0110mm.

[0104] Then we get:|(f G1 ×f / (f G2 +f G3 ))×tan(FOV / 4)|=0.6574; (FOV×f) / IH=111.4849;|f u1 / f|=2.2949;|f u2 / f|=2.0021; SD max / TTL=0.37; FOV / (D×TTL)=0.0115; IH / FNO=5.2263; f / IH=2.5807.

[0105] The final imaging effect of the lens in this example is achieved through Figure 5 The MTF graph of the lens shows that the MTF curves in each field of view all drop gently and have good consistency. From the graph, we can see that the MTF value is greater than 0.5 at the spatial frequency of 80pl / mm in the edge field of view, which means that the lens has good imaging effect and resolution in the full field of view. Figure 6 This is the field curvature distortion diagram of the lens of this embodiment. It can be seen that the distortion of the lens does not exceed 3%. Example 3

[0106] In this example, in the optical system, the first lens L1 is a positive lens with the convex surface facing the object; the second lens L2 is a negative meniscus lens with the convex surface facing the object; the third lens L3 is a double concave negative lens; the fourth lens L4 is a negative meniscus lens with the convex surface facing the image; the fifth lens L5 is a positive meniscus lens with the convex surface facing the image; the sixth lens L6 is a double convex positive lens; the seventh lens L7 is a negative meniscus lens with the convex surface facing the object; the eighth lens L8 is a double convex positive lens; the ninth lens L9 is a double concave negative lens; the tenth lens L10 is a positive meniscus lens with the convex surface facing the image; the eleventh lens L11 is a double convex positive lens; and the twelfth lens L12 is a double concave negative lens. The fourth lens L4 is glued to the fifth lens L5, the eighth lens L8 is glued to the ninth lens L9, and the eleventh lens L11 is glued to the twelfth lens L12. The optical path diagram of the monitoring lens is shown in Figure 7 shown.

[0107] See Table 3, which lists the relevant parameters of each lens in this example, including the radius of curvature, thickness, refractive index of the material, and Abbe number:

[0108] Table 3

[0109]

[0110] In this example, the air distance from the first lens L1 to the second lens L2 is 2.1897 mm; the air distance from the second lens L2 to the third lens L3 is 11.2816 mm; the air distance from the third lens L3 to the fourth lens L4 is 1.3679 mm; the air distance from the fifth lens L5 to the sixth lens L6 is 1.0886 mm; the air distance from the sixth lens L6 to the aperture C is 1.4864 mm; the air distance from the aperture C to the seventh lens L7 is 3.6000 mm; the air distance from the seventh lens L7 to the eighth lens L8 is 2.6114 mm; the air distance from the ninth lens L9 to the tenth lens L10 is 3.4116 mm; the air distance from the tenth lens L10 to the eleventh lens L11 is 0.1382 mm; and the air distance from the twelfth lens L12 to the image plane IMG is 13.3133 mm.

[0111] The technical indicators achieved by the optical system in this example are as follows:

[0112] 1) Maximum field of view of the surveillance camera: FOV = 43.2°;

[0113] 2) Effective focal length of the front lens: f u1 =47.2374mm;

[0114] 3) Effective focal length of the rear lens: f u2 =41.8899mm;

[0115] 4) Effective focal length of the first cemented lens group: f G1 =48.07mm;

[0116] 5) Effective focal length of the second lens group: f G2 =-3552.27 mm;

[0117] 6) Effective focal length of the third cemented lens group; f G3 =54.01mm;

[0118] 7) Effective focal length of surveillance lens: f=20.4362mm;

[0119] 8) Maximum image height of the monitoring lens: IH = 7.9040mm;

[0120] 9) Aperture value of monitoring lens: FNO = 1.5038;

[0121] 10) Monitoring lens head aperture size: D = 35.8954mm;

[0122] 11) The largest aperture of the surveillance lens: SD max =35.8954mm;

[0123] 12) Total optical length of the monitoring lens: TTL = 101.018mm.

[0124] Then we get:|(f G1 ×f / (f G2 +f G3 ))×tan(FOV / 4)|=0.0536; (FOV×f) / IH=111.6958;|f u1 / f|=2.3115;|f u2 / f|=2.0498;SD max / TTL=0.36; FOV / (D×TTL)=0.0119; IH / FNO=5.2559; f / IH=2.5856.

[0125] The final imaging effect of the lens in this example is achieved through Figure 8-9 To evaluate, from Figure 8 It can be seen that the MTF value of the edge field of view is greater than 0.55 at the spatial frequency of 80pl / mm; Fig. 9 : is the field curvature distortion diagram of the lens of this embodiment, from which it can be seen that the distortion of the lens does not exceed 4%.

[0126] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A surveillance lens with small size, large light transmission and low distortion, characterized in that: The monitoring lens has twelve lenses in total, which include, in order from the object side to the image side along the optical axis: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, an aperture C, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11 and a twelfth lens L12, The first lens L1, the fifth lens L5, the sixth lens L6, the eighth lens L8, the tenth lens L10 and the eleventh lens L11 have positive refractive power; the second lens L2, the third lens L3, the fourth lens L4, the seventh lens L7, the ninth lens L9 and the twelfth lens L12 have negative refractive power; In the monitoring lens, The first lens L1 is a biconvex positive lens or a meniscus positive lens with the convex surface facing the object; The second lens L2 is a negative meniscus lens with its convex surface facing the object; The third lens L3 is a double concave negative lens; The fourth lens L4 is a negative meniscus lens with a convex surface facing the image side; The fifth lens L5 is a positive meniscus lens with a convex surface facing the image side; The sixth lens L6 is a biconvex positive lens; The seventh lens L7 is a negative meniscus lens with a convex surface facing the object; The eighth lens L8 is a biconvex positive lens; The ninth lens L9 is a double concave negative lens; The tenth lens L10 is a biconvex positive lens or a meniscus positive lens with the convex surface facing the image side; The eleventh lens L11 is a biconvex positive lens; The twelfth lens L12 is a double concave negative lens; Among them, the fourth lens L4 and the fifth lens L5 are closely connected to form a first cemented lens group; the eighth lens L8 and the ninth lens L9 are closely connected to form a second cemented lens group; the eleventh lens L11 and the twelfth lens L12 are closely connected to form a third cemented lens group; The first lens L1 to the sixth lens L6 constitute a front lens group; the seventh lens L7 to the twelfth lens L12 constitute a rear lens group; The surveillance camera meets the following conditions: 0.05≤|(f G1 ×f / (f G2 +f G3 ))×tan(FOV / 4)|≤0.8, where f G1 f is the effective focal length of the first cemented lens group; G2 is the effective focal length of the second cemented lens group; f G3 is the effective focal length of the third cemented lens group; FOV is the maximum field of view of the monitoring lens; The surveillance camera meets the following conditions: u1 / f|≤2.4,2≤|f u2 / f|≤2.0498, where f u1 is the effective focal length of the front lens group, f u2 is the effective focal length of the rear lens group, and f is the effective focal length of the monitoring lens.

2. The small-volume, high-light-through, low-distortion surveillance lens according to claim 1, characterized in that: The monitoring lens satisfies the following condition: 111.2340≤(FOV×f) / IH≤112, where FOV is the maximum field of view of the monitoring lens, f is the effective focal length of the monitoring lens, and IH is the maximum image plane height of the monitoring lens.

3. The small-volume, high-light-through, low-distortion surveillance lens according to claim 1, characterized in that: The surveillance camera meets the following conditions: SD max / TTL≤0.4, where SD max is the clear aperture of the largest lens in the monitoring lens, and TTL is the total optical length of the monitoring lens, that is, the distance from the center of the object side of the first lens L1 to the imaging surface.

4. The small-volume, high-light-through, low-distortion surveillance lens according to claim 1, characterized in that: The monitoring lens satisfies the following condition: 0.01≤FOV / (D×TTL) ≤0.0119, where FOV is the maximum field of view of the monitoring lens, D is the aperture size of the monitoring lens head, and TTL is the total optical length of the monitoring lens.

5. The small-volume, high-light-through, low-distortion surveillance lens according to claim 1, characterized in that: The monitoring lens satisfies the following condition: 5.2≤IH / FNO≤5.2559, where IH is the maximum image plane height of the monitoring lens, and FNO is the aperture value of the monitoring lens.

6. The small-volume, high-light-through, low-distortion surveillance lens according to claim 1, characterized in that: The monitoring lens satisfies the following condition: 2.5≤f / IH≤2.5856, where f is the effective focal length of the monitoring lens and IH is the maximum image plane height of the monitoring lens.

7. The small-volume, high-light-through, low-distortion surveillance lens according to claim 1, characterized in that: The monitoring lens satisfies the following condition: 101.0110mm≤TTL≤102mm, where TTL is the total optical length of the monitoring lens.

Images