Zoom lens

Abstract

The present invention relates to a zoom lens, comprising a first lens group (G1) with negative optical power, a stop (STO) and a second lens group (G2) with positive optical power, which are arranged in sequence from the object side to the image side along the optical axis. When the zoom lens is changing the magnification, the first lens group (G1) and the second lens group (G2) can both move along the optical axis, and the second lens group (G2) has six lenses. The zoom lens of the present invention has the advantages of large magnification, infrared light and visible light confocality, and can solve the problem of temperature drift.

Description

Technical Field

[0001] The present invention relates to the technical field of optical imaging, and in particular to a zoom lens. Background Art

[0002] With the development of the times, the number of transportation vehicles has increased dramatically, and surveillance cameras also need to be able to produce clear images at both ends. Since the focal length of a zoom lens is variable, it can be used in this type of surveillance scenario, so it is becoming more and more popular in the security surveillance market. In order to obtain clear images at both ends, the surveillance lens needs to have sufficient zoom effect, but this will also increase the complexity of the lens in the design process, and the cost will also increase accordingly, resulting in a low overall cost performance of the lens. In addition, the market has higher and higher requirements for security surveillance lenses, requiring the lens to achieve infrared confocality in the process of zooming from the wide-angle end to the telephoto end, and to ensure the same resolution as at normal temperature without refocusing at high and low temperatures. However, the existing surveillance zoom lenses still have some defects that limit their use scenarios and cannot take into account the above requirements at the same time. Summary of the invention

[0003] The purpose of the present invention is to solve the above-mentioned problem and provide a zoom lens.

[0004] To achieve the above-mentioned object of the invention, the present invention provides a zoom lens, comprising a first lens group with negative optical focal length, an aperture and a second lens group with positive optical focal length, which are arranged in sequence from the object side to the image side along the optical axis. When the zoom lens is changed in magnification, the first lens group and the second lens group can both move along the optical axis, and the second lens group has six lenses.

[0005] According to one aspect of the present invention, the second lens group includes a fourth lens with positive optical power, a fifth lens with positive optical power, a sixth lens with positive optical power or negative optical power, a seventh lens with positive optical power, an eighth lens with negative optical power, and a ninth lens with positive optical power, which are arranged in sequence from the object side to the image side along the optical axis.

[0006] According to one aspect of the present invention, in the second lens group, the seventh lens and the eighth lens form a cemented lens group.

[0007] According to one aspect of the present invention, the fourth lens is a biconvex or convexoconcave lens, the fifth lens is a convexoconcave lens, the sixth lens is a convexoconcave or concave-convex lens, the seventh lens is a biconvex lens, the eighth lens is a concave-convex or biconcave lens; and the ninth lens is a convexoconcave lens.

[0008] According to one aspect of the present invention, the first lens group includes a first lens with negative optical power, a second lens with negative optical power, and a third lens with positive optical power, which are arranged in sequence from the object side to the image side along the optical axis.

[0009] According to one aspect of the present invention, the first lens is a convexo-concave lens, the second lens is a bi-concave lens, and the third lens is a convexo-concave or bi-convex lens.

[0010] According to one aspect of the present invention, the focal length Fw at the wide-angle end and the focal length Ft at the telephoto end of the zoom lens respectively satisfy the following relationship with the focal length Fa of the first lens group:

[0011] -4.4≤Fa / Fw≤-3.1;

[0012] -1.3≤Fa / Ft≤-0.85.

[0013] According to one aspect of the present invention, the focal length Fw at the wide-angle end and the focal length Ft at the telephoto end of the zoom lens respectively satisfy the following relationship with the focal length Fb of the second lens group:

[0014] 0.2≤Fw / Fb≤0.35;

[0015] 0.8≤Ft / Fb≤1.3.

[0016] According to one aspect of the present invention, the focal length f4 of the fourth lens and the focal length Fb of the second lens group satisfy the relationship:

[0017] 1.25≤f4 / Fb≤2.05.

[0018] According to one aspect of the present invention, the refractive index Nd4 and the Abbe number Vd4 of the fourth lens, and the refractive index Nd7 and the Abbe number Vd7 of the seventh lens respectively satisfy the following conditions:

[0019] 1.4≤Nd4≤1.6;

[0020] 50≤Vd4≤96;

[0021] 1.4≤Nd7≤1.7;

[0022] 60≤Vd7≤82.

[0023] According to one aspect of the present invention, the fifth lens, the sixth lens and the ninth lens are aspherical lenses.

[0024] According to one aspect of the present invention, the fifth lens, the sixth lens and the ninth lens are plastic lenses.

[0025] According to one aspect of the present invention, the focal length f5 of the fifth lens and the focal length f6 of the sixth lens satisfy the following relationship:

[0026] -2.3≤f5 / f6≤0.95.

[0027] According to the solution of the present invention, a zoom lens with large magnification, infrared light and visible light confocality, and temperature drift problem solving is provided. The lens comprises two lens groups arranged along the optical axis and an aperture located between the two lens groups. Both lens groups can move during the zooming process, wherein the first lens group moves to achieve the change of the image plane position during the zooming process, correct the aberration and distortion of the system, and reduce the tolerance sensitivity to ensure the uniformity of the picture; the movement of the second lens group can achieve the zooming from the wide-angle end to the telephoto end while also ensuring a small change in the aperture value and a small image side chief ray angle. The second lens group has six lenses, and the last lens in the lens (i.e., the ninth lens) is a plastic aspherical lens, which is better than a glass spherical lens in eliminating most aberrations such as spherical aberration, coma, field curvature, and distortion, can reduce the complexity of the system, improve the optical imaging quality, achieve infrared confocality and no false focus at high and low temperatures, and the focal length of the plastic aspherical surface also plays a key role in high and low temperature correction.

[0028] According to one solution of the present invention, by reasonably setting the positive and negative optical focal lengths of each lens in the first lens group, imaging light can be well collected and large aperture imaging can be achieved, which is beneficial for correcting spherical aberration, astigmatism, distortion and high and low temperature performance within the first lens group. At the same time, it can also reduce the tolerance sensitivity within the group and ensure the uniformity of the image.

[0029] According to one solution of the present invention, by reasonably setting the positive and negative optical power of each lens in the second lens group and appropriately setting the cemented lens group, it is beneficial to correct the spherical aberration, chromatic aberration, astigmatism and distortion inside the second lens group. The correction of the aberration inside the second lens group is beneficial to reducing the burden ratio of the first lens group on the aberration correction, which can better reduce the tolerance sensitivity of the active group, and is beneficial to the correction of high and low temperature performance, and comprehensively improves the imaging quality of the optical system.

[0030] According to one solution of the present invention, by using the cemented lens group reasonably, spherical aberration, chromatic aberration and astigmatism can be well corrected, and it is also beneficial to correct high and low temperature performance. Then, by configuring the positive and negative lenses on the most image side, the incident angle of the image side principal ray can be reduced, while ensuring sufficient back focus, and also avoiding the degradation of focusing performance. By reasonably setting the positive and negative optical power of the seventh and eighth lenses constituting the cemented lens group in the second lens group, chromatic aberration, spherical aberration and temperature performance can be corrected, while it is easy to ensure tolerance sensitivity, and the refractive power of the positive lens is reduced by using the lens with negative refractive power, so that the lens can better achieve full-frame imaging of a large image plane and a smaller incident angle of the image plane principal ray, so that the color reproduction is better and the infrared confocal performance is achieved.

[0031] According to one solution of the present invention, through the reasonable combination of positive and negative lenses, it is beneficial to collect imaging light and achieve large aperture imaging. It can well correct spherical aberration, astigmatism, distortion, high and low temperature performance, and expand the field of view of the optical system, reduce the optical aperture of the lens, and also avoid the degradation of focusing performance.

[0032] According to one solution of the present invention, by reasonably setting the relationship between the focal length at the wide-angle end, the focal length at the telephoto end and the focal length of the second lens group, the aberration balance at the telephoto end can be restricted, and the resolution can be improved. At the same time, it can also avoid the difficulty of the lens in taking into account the requirements of large-magnification zoom and small volume. In addition, the aberration generated by the zoom group can be effectively reduced, while the aberration of the focus group can be shared, thereby improving the image quality of the entire system.

[0033] According to one solution of the present invention, by reasonably setting the relationship between the focal length of the fourth lens and the focal length of the second lens group, the aberrations produced by the zoom group can be effectively reduced, while the aberrations of the focusing group are shared, the image quality of the entire system is improved, and it is beneficial to the correction of high and low temperatures.

[0034] According to one solution of the present invention, by reasonably setting the refractive index and Abbe number of the fourth lens and the seventh lens, the chromatic aberration at the wide-angle end and the telephoto end can be corrected, a reasonable balance of chromatic aberration throughout the zoom range can be achieved, the infrared defocus amount can be reduced, and the resolution of visible light and infrared light can be improved.

[0035] According to one solution of the present invention, the fifth lens, the sixth lens and the ninth lens are all aspherical lenses. In this way, most aberrations such as spherical aberration, coma, field curvature, distortion, etc. can be eliminated, the complexity of the system can be reduced, the optical imaging quality can be improved, and the entire zoom lens can achieve infrared confocality during the zoom process from the wide-angle end to the telephoto end, and the same resolution as that at room temperature can be guaranteed without refocusing at high and low temperatures.

[0036] According to one solution of the present invention, the fifth lens, the sixth lens and the ninth lens are all plastic aspherical lenses, which can eliminate most aberrations such as spherical aberration, coma, field curvature, distortion, etc., can reduce the complexity of the system, improve the optical imaging quality, and achieve infrared confocal and no false focus at high and low temperatures. By reasonably setting the relationship between the focal lengths of the fifth lens and the sixth lens, it can be more conducive to high and low temperature performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram showing the structure of a zoom lens at a wide-angle end (W) when the object distance is infinite according to a first embodiment of the present invention;

[0038] Figure 2 A schematic diagram showing the structure of a zoom lens at a telephoto end (T) when the object distance is infinite according to a first embodiment of the present invention;

[0039] Figure 3 Schematically showing an MTF diagram of the zoom lens of the first embodiment of the present invention at the wide angle end (W) when the object distance is infinite;

[0040] Figure 4 A diagram schematically showing vertical chromatic aberration of the zoom lens according to the first embodiment of the present invention at the wide-angle end (W) when the object distance is infinite;

[0041] Figure 5 A diagram schematically showing the distortion of the zoom lens at the wide-angle end (W) when the object distance is infinite according to the first embodiment of the present invention;

[0042] Figure 6 Schematically showing an MTF diagram at the telephoto end (T) of the zoom lens according to the first embodiment of the present invention when the object distance is infinite;

[0043] Figure 7 A diagram schematically showing vertical axis chromatic aberration at the telephoto end (T) of the zoom lens according to the first embodiment of the present invention when the object distance is infinite;

[0044] Figure 8 Schematically showing the distortion diagram of the zoom lens at the telephoto end (T) when the object distance is infinite according to the first embodiment of the present invention;

[0045] Fig. 9 A schematic diagram showing the structure of a zoom lens at a wide-angle end (W) when the object distance is infinite according to a second embodiment of the present invention;

[0046] Fig.10 A diagram schematically showing the structure of a zoom lens at a telephoto end (T) when the object distance is infinite according to a second embodiment of the present invention;

[0047] Fig.11 Schematically showing an MTF diagram of the zoom lens of the second embodiment of the present invention at the wide angle end (W) when the object distance is infinite;

[0048] Fig.12 A diagram schematically showing vertical axial chromatic aberration of a zoom lens according to a second embodiment of the present invention at a wide angle end (W) when the object distance is infinite;

[0049] Fig.13 A diagram schematically showing the distortion of the zoom lens at the wide-angle end (W) when the object distance is infinite according to the second embodiment of the present invention;

[0050] Fig.14 Schematically showing an MTF diagram at the telephoto end (T) of the zoom lens according to the second embodiment of the present invention when the object distance is infinite;

[0051] Fig.15A diagram schematically showing vertical axis chromatic aberration at the telephoto end (T) of the zoom lens according to the second embodiment of the present invention when the object distance is infinite;

[0052] Fig.16 A diagram schematically showing the distortion of the zoom lens at the telephoto end (T) when the object distance is infinite according to the second embodiment of the present invention;

[0053] Fig.17 A schematic diagram showing the structure of a zoom lens at a wide-angle end (W) when the object distance is infinite according to a third embodiment of the present invention;

[0054] Fig.18 A schematic diagram showing the structure of a zoom lens at a telephoto end (T) when the object distance is infinite according to a third embodiment of the present invention;

[0055] Fig.19 Schematically showing an MTF diagram of a zoom lens according to a third embodiment of the present invention at a wide angle end (W) when the object distance is infinite;

[0056] Fig. 20 A diagram schematically showing vertical axial chromatic aberration of a zoom lens according to a third embodiment of the present invention at a wide angle end (W) when the object distance is infinite;

[0057] Fig.21 A diagram schematically showing the distortion of the zoom lens at the wide-angle end (W) when the object distance is infinite according to the third embodiment of the present invention;

[0058] Fig. 22 Schematically showing an MTF diagram at the telephoto end (T) of the zoom lens according to the third embodiment of the present invention when the object distance is infinite;

[0059] Fig.23 A diagram schematically showing vertical axis chromatic aberration at the telephoto end (T) of the zoom lens according to the third embodiment of the present invention when the object distance is infinite;

[0060] Fig.24 A diagram schematically showing the distortion of the zoom lens at the telephoto end (T) when the object distance is infinite according to the third embodiment of the present invention;

[0061] Fig.25 A schematic diagram showing the structure of a zoom lens according to a fourth embodiment of the present invention at a wide-angle end (W) when the object distance is infinite;

[0062] Fig.26 A diagram schematically showing the structure of a zoom lens at a telephoto end (T) when the object distance is infinite according to a fourth embodiment of the present invention;

[0063] Fig. 27 Schematically showing an MTF diagram of a zoom lens according to a fourth embodiment of the present invention at a wide angle end (W) when the object distance is infinite;

[0064] Fig.28 A diagram schematically showing vertical axial chromatic aberration of a zoom lens according to a fourth embodiment of the present invention at a wide angle end (W) when the object distance is infinite;

[0065] Fig.29 A diagram schematically showing the distortion of the zoom lens of the fourth embodiment of the present invention at the wide-angle end (W) when the object distance is infinite;

[0066] Fig.30 Schematically showing an MTF diagram at the telephoto end (T) of the zoom lens according to the fourth embodiment of the present invention when the object distance is infinite;

[0067] Fig.31 A diagram schematically showing vertical axis chromatic aberration at the telephoto end (T) of the zoom lens according to the fourth embodiment of the present invention when the object distance is infinite;

[0068] Fig.32 A distortion diagram schematically shows a zoom lens according to a fourth embodiment of the present invention at the telephoto end (T) when the object distance is infinite. DETAILED DESCRIPTION

[0069] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0070] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0071] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0072] See also Figure 1 The zoom lens of the present invention comprises a first lens group G1 with negative power, an aperture STO and a second lens group G2 with positive power, which are arranged in sequence from the object side to the image side along the optical axis. Figure 2It can be seen that when the zoom lens is changing magnification, both the first lens group G1 and the second lens group G2 can move along the optical axis. Specifically, when the zoom lens changes magnification from the wide-angle end to the telephoto end, the second lens group G2 (i.e., the zoom group) moves along the optical axis from the object side to the image side, and at the same time, the first lens group G1 (i.e., the focusing group or the compensation group) moves along the optical axis to achieve the change of the image plane position during the zoom process. The focal length Fw at the wide-angle end and the focal length Ft at the telephoto end of the zoom lens respectively satisfy the following relationship with the focal length Fa of the first lens group G1: -4.4≤Fa / Fw≤-3.1; -1.3≤Fa / Ft≤-0.85. In this way, the movement of the first lens group G1 mainly serves to achieve the change of the image plane position during the zoom process, correct the aberration and distortion of the system, and reduce the tolerance sensitivity to ensure the uniformity of the picture. By moving the second lens group G2, it is possible to achieve a small change in aperture value and a small image-side chief ray angle while achieving a zoom from the wide-angle end to the telephoto end.

[0073] In the present invention, the first lens group G1 includes a first lens L1 with negative optical power, a second lens L2 with negative optical power, and a third lens L3 with positive optical power, which are arranged in sequence from the object side to the image side along the optical axis. By using the optical power of the above-mentioned positive and negative lenses in combination, it is possible to collect imaging light well and achieve large aperture imaging, which is conducive to correcting the spherical aberration, astigmatism, distortion and high and low temperature performance inside the first lens group G1, and at the same time, it is also possible to reduce the tolerance sensitivity within the group and ensure the uniformity of the picture. The first lens L1 is a convex-concave lens, the second lens L2 is a biconcave lens, and the third lens L3 is a convex-concave or biconvex lens. Through the reasonable combination of positive and negative lenses, it is conducive to collecting imaging light, achieving large aperture imaging, and can well correct spherical aberration, astigmatism, distortion, high and low temperature performance, and expand the field angle of the optical system, reduce the optical aperture of the lens, and also avoid the degradation of focusing performance.

[0074] In the present invention, the second lens group G2 has six lenses, specifically including a fourth lens L4 with positive focal power, a fifth lens L5 with positive focal power, a sixth lens L6 with positive focal power or negative focal power, a seventh lens L7 with positive focal power, an eighth lens L8 with negative focal power, and a ninth lens L9 with positive focal power, which are arranged in sequence from the object side to the image side along the optical axis. In this way, the focal power matching of positive and negative lenses and the use of cemented sheets in the lens group G2 are conducive to correcting the spherical aberration, chromatic aberration, astigmatism and distortion inside the second lens group G2. The correction of the aberration inside the second lens group G2 is conducive to reducing the burden ratio of the first lens group G1 for aberration correction, can better reduce the tolerance sensitivity of the active group, and is conducive to the correction of high and low temperature performance, and comprehensively improves the imaging quality of the optical system.

[0075] In the present invention, in the second lens group G2, the seventh lens L7 and the eighth lens L8 form a cemented lens group. Therefore, the second lens group G2 corrects chromatic aberration, spherical aberration and temperature performance through the cemented lens group, and is easy to ensure tolerance sensitivity at the same time, and reduces the refractive power of the positive lens through the lens of negative refractive power, so that the lens can better achieve full-frame imaging of a large image plane and a smaller incident angle of the main light of the image plane, so that the color reproduction is better and the infrared confocal performance is achieved.

[0076] In the present invention, the fourth lens L4 in the second lens group G2 is a biconvex or convexo-concave lens, the fifth lens L5 is a convexo-concave lens, the sixth lens L6 is a convexo-concave or concave-convex lens, the seventh lens L7 is a biconvex lens, the eighth lens L8 is a concave-convex or biconcave lens; and the ninth lens L9 is a convexo-concave lens. By using cemented sheets reasonably, spherical aberration, chromatic aberration and astigmatism can be well corrected, and it is also beneficial to correct high and low temperature performance. Then, by configuring positive and negative lenses on the most image side, the incident angle of the image side principal ray can be reduced, while ensuring sufficient back focus, and also avoiding the degradation of focusing performance.

[0077] In the present invention, the focal length Fw at the wide-angle end and the focal length Ft at the telephoto end of the zoom lens respectively satisfy the following relationships with the focal length Fb of the second lens group G2: 0.2≤Fw / Fb≤0.35; 0.8≤Ft / Fb≤1.3. When the value is less than the lower limit of the above relationship, the aberration balance at the telephoto end is limited, and it is difficult to improve the resolution. When the value is greater than the upper limit of the above relationship, it is difficult for the lens to take into account both the requirements of large-magnification zoom and small volume. In this way, the lens of the present invention satisfies the above relationship, which can effectively reduce the aberrations generated by the zoom group, while sharing the aberrations of the focusing group, and improving the image quality of the entire system.

[0078] In the present invention, the focal length f4 of the fourth lens L4 and the focal length Fb of the second lens group G2 satisfy the relationship: 1.25≤f4 / Fb≤2.05. Satisfying the above relationship can effectively reduce the aberrations generated by the zoom group, while sharing the aberrations of the focus group, improve the image quality of the entire system, and facilitate the correction of high and low temperatures. The refractive index Nd4 and Abbe number Vd4 of the fourth lens L4, and the refractive index Nd7 and Abbe number Vd7 of the seventh lens L7 respectively satisfy the following conditions: 1.4≤Nd4≤1.6; 50≤Vd4≤96; 1.4≤Nd7≤1.7; 60≤Vd7≤82. Satisfying the above relationship can achieve the correction of chromatic aberration at the wide-angle end and the telephoto end, achieve a reasonable balance of chromatic aberration throughout the zoom range, reduce the infrared defocus amount, and improve the resolution of visible light and infrared light.

[0079] Aspherical lenses are better than glass spherical lenses in eliminating most aberrations such as spherical aberration, coma, field curvature, distortion, etc., which can reduce the complexity of the system and improve the quality of optical imaging. Using aspherical lenses at specific positions can enable the entire imaging system to achieve infrared confocality during the process of changing magnification from the wide-angle end to the telephoto end, and to ensure the same resolution as at room temperature without refocusing at high and low temperatures. Therefore, in the present invention, the fifth lens L5, the sixth lens L6 and the ninth lens L9 are aspherical lenses.

[0080] Plastic aspheric lenses are better than glass spherical lenses in eliminating most aberrations such as spherical aberration, coma, field curvature, distortion, etc., can reduce the complexity of the system, improve the quality of optical imaging, and achieve infrared confocal and no false focus at high and low temperatures. Therefore, in the present invention, the fifth lens L5, the sixth lens L6 and the ninth lens L9 are all plastic lenses. In addition, the focal length of the plastic aspheric surface is the key to high and low temperature correction. Therefore, in the present invention, the focal length of the fifth lens L5 is f5 and the focal length of the sixth lens L6 is f6, which satisfies the following relationship: -2.3≤f5 / f6≤0.95. Satisfying the above conditional formula will be more conducive to high and low temperature performance.

[0081] The zoom lens according to the above settings adopts a glass-plastic hybrid structure, and reasonably distributes anomalous dispersion glass and high refractive index glass to achieve high-quality imaging effects, with ultra-wide angle, large aperture, and low-cost performance. In addition, by reasonably matching positive and negative optical focal lenses, the wide-angle end to the telephoto end has a large magnification effect, and is conducive to the correction of temperature drift under high and low temperatures. The use of plastic aspherical lenses is also conducive to eliminating most aberrations such as spherical aberration, coma, field curvature, and distortion of the entire optical system, improving the optical imaging quality, and greatly eliminating the back focus drift caused by temperature changes, so that the lens can maintain the same resolution as normal temperature without refocusing when the ambient temperature changes from -30°C to 70°C. The setting of the cemented lens group is conducive to correcting the chromatic aberration and spherical aberration of the entire optical system, and achieving visible light and infrared confocal performance.

[0082] The zoom lens of the present invention is specifically described in four embodiments. In the following embodiments, sur1, sur2, ..., surN are used to represent the surface of each lens, the aperture STO surface is denoted as Stop, and the image surface is denoted as Image. The surface shape of the aspheric lens satisfies the following aspheric surface equation:

[0083] Z=cy 2 / {1+[1-(1+k)c 2 y 2 ] 1 / 2}+a4y 4 +a6y 6 +a8y 8 +a 10 y 10 +a12 y 12 +a 14 y 14 ;

[0084] Among them, parameter c is the curvature corresponding to the radius of the aspheric lens, y is the radial coordinate of the aspheric lens, and its unit is the same as the lens length unit, k is the conic quadratic curve coefficient of the aspheric lens, a4, a6…a 14 are the corresponding order coefficients of the aspheric surface respectively.

[0085] The parameters of each implementation are shown in Table 1 below:

[0086]

[0087] Table 1

[0088] First Implementation Method

[0089] Combination Figure 1 and Figure 2 In this embodiment, the third lens L3 is a convex-concave lens, the fourth lens L4 is a convex-concave lens, the sixth lens L6 is a convex-concave lens, and the eighth lens L8 is a convex-concave lens. The sixth lens L6 has negative power.

[0090] In this embodiment, the parameters of the zoom lens are: TTL=52-79.05mm; FNO=1.60-2.7; focal length fw at the wide angle end=3.22mm; focal length ft at the telephoto end=11.65mm. TTL and FNO can be changed within the above range during the zoom process.

[0091] The relevant parameters of each lens in this embodiment are shown in Table 2 below:

[0092] Surface Type Radius Thickness nd vd sur1 standard 58.9 1.6 1.88 38.2 sur2 standard 18.21 7.44 sur3 standard -28.88 0.6 1.46 90.2 sur4 standard 21.88 0.57 sur5 standard 28.56 1.90 1.95 18 sur6 standard 48.20 30.03 (movable) Stop standard INF 12.08 (movable) Sur8 standard 23.15 1.74 1.58 55.6 Sur9 standard 78.15 1.70 sur10 EvenAsphere 12 1.84 1.48 67 sur11 EvenAsphere 19.35 0.31 sur12 EvenAsphere 28.8 0.6 1.6 31 sur13 EvenAsphere 8.65 0.37 Sur14 standard 6.99 3.01 1.49 80 Sur15 standard -18.56 4.24 1.63 28 Sur16 standard -78.03 0.1 Sur17 EvenAsphere 27.65 2.21 1.73 53.6 Sur18 EvenAsphere 48.27 8.71 (movable) Image

[0093] Table 2

[0094] The aspheric coefficients in this embodiment are shown in Table 3 below:

[0095]

[0096]

[0097] Table 3

[0098] Among them, the refractive index Nd4 and the Abbe number Vd4 of the fourth lens L4 in the second lens group G2 are: Nd4=1.58; Vd4=55.6 respectively, and the refractive index Nd7 and the Abbe number Vd7 of the seventh lens L7 in the second lens group G2 are: Nd7=1.49; Vd7=80 respectively.

[0099] Combination Figures 3 to 8 The zoom lens of this embodiment has ultra-wide angle, large aperture, and low cost performance; it has a large magnification effect from the wide-angle end to the telephoto end, and is conducive to the correction of temperature drift under high and low temperatures, and can achieve visible light and infrared confocality.

[0100] Second implementation method

[0101] Combination Fig. 9 and Fig.10 In this embodiment, the third lens L3 is a biconvex lens, the fourth lens L4 is a biconvex lens, the sixth lens L6 is a meniscus lens, and the eighth lens L8 is a biconcave lens. The sixth lens L6 has positive refractive power.

[0102] In this embodiment, the parameters of the zoom lens are: TTL=50-79mm; FNO=1.6-2.7; focal length fw at the wide angle end=3.22mm; focal length ft at the telephoto end=11.65mm. TTL and FNO can be changed within the above range during the zoom process.

[0103] The relevant parameters of each lens in this embodiment are shown in Table 4 below:

[0104]

[0105]

[0106] Table 4 The aspheric coefficients in this embodiment are shown in Table 5 below:

[0107]

[0108] Table 5

[0109] The refractive index Nd4 and the Abbe number Vd4 of the fourth lens L4 in the second lens group G2 are respectively: Nd4=1.43; Vd4=95. The refractive index Nd7 and the Abbe number Vd7 of the seventh lens L7 in the second lens group G2 are respectively: Nd7=1.49; Vd7=66.

[0110] Combination Figures 11 to 16 The zoom lens of this embodiment has ultra-wide angle, large aperture, and low cost performance; it has a large magnification effect from the wide-angle end to the telephoto end, and is conducive to the correction of temperature drift under high and low temperatures, and can achieve visible light and infrared confocality.

[0111] The third implementation method

[0112] Combination Fig.17 and Fig.18 In this embodiment, the third lens L3 is a convex-concave lens, the fourth lens L4 is a convex-concave lens, the sixth lens L6 is a convex-concave lens, and the eighth lens L8 is a biconcave lens. The sixth lens L6 has negative power.

[0113] In this embodiment, the parameters of the zoom lens are: TTL = 47-67.43 mm; FNO = 1.6-2.7; focal length fw at the wide angle end = 3.29; focal length ft at the telephoto end = 11.65. TTL and FNO can be changed within the above range during the zoom process.

[0114] The relevant parameters of each lens in this embodiment are shown in Table 6 below:

[0115]

[0116]

[0117] Table 6 The aspheric coefficients in this embodiment are shown in Table 7 below:

[0118]

[0119] Table 7

[0120] The refractive index Nd4 and the Abbe number Vd4 of the fourth lens L4 in the second lens group G2 are respectively: Nd4=1.51; Vd4=66. The refractive index Nd7 and the Abbe number Vd7 of the seventh lens L7 in the second lens group G2 are respectively: Nd7=1.60; Vd7=68.

[0121] Combination Figures 19 to 24 The zoom lens of this embodiment has ultra-wide angle, large aperture, and low cost performance; it has a large magnification effect from the wide-angle end to the telephoto end, and is conducive to the correction of temperature drift under high and low temperatures, and can achieve visible light and infrared confocality.

[0122] Fourth Implementation Method

[0123] Combination Fig.25 and Fig.26 In this embodiment, the third lens L3 is a convex-concave lens, the fourth lens L4 is a biconvex lens, the sixth lens L6 is a convex-concave lens, and the eighth lens L8 is a convex-concave lens. The sixth lens L6 has negative optical power.

[0124] In this embodiment, the parameters of the zoom lens are: TTL = 52.4-72.18 mm; FNO = 1.6-2.9; focal length fw at the wide angle end = 3.22; focal length ft at the telephoto end = 11.7. TTL and FNO can be changed within the above range during the zoom process.

[0125] The relevant parameters of each lens in this embodiment are shown in Table 8 below:

[0126]

[0127]

[0128] Table 8 The aspheric coefficients in this embodiment are shown in Table 9 below:

[0129]

[0130] Table 9

[0131] The refractive index Nd4 and the Abbe number Vd4 of the fourth lens L4 in the second lens group G2 are respectively: Nd4=1.54; Vd4=57. The refractive index Nd7 and the Abbe number Vd7 of the seventh lens L7 in the second lens group G2 are respectively: Nd7=1.59; Vd7=68.6.

[0132] Combination Figures 27 to 32 The zoom lens of this embodiment has ultra-wide angle, large aperture, and low cost performance; it has a large magnification effect from the wide-angle end to the telephoto end, and is conducive to the correction of temperature drift under high and low temperatures, and can achieve visible light and infrared confocality.

[0133] The above is only one embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A zoom lens, comprising a first lens group (G1) with negative optical power, a stop (STO) and a second lens group (G2) with positive optical power, which are arranged in sequence from the object side to the image side along the optical axis, a total of two lens groups, when the zoom lens is changing magnification, the first lens group (G1) and the second lens group (G2) can both move along the optical axis, characterized in that: The first lens group (G1) has three lenses, and the second lens group (G2) has six lenses; The first lens group (G1) comprises a first lens (L1) with negative optical power, a second lens (L2) with negative optical power and a third lens (L3) with positive optical power, which are arranged in sequence from the object side to the image side along the optical axis; the second lens group (G2) comprises a fourth lens (L4) with positive optical power, a fifth lens (L5) with positive optical power, a sixth lens (L6) with positive optical power or negative optical power, a seventh lens (L7) with positive optical power, an eighth lens (L8) with negative optical power and a ninth lens (L9) with positive optical power, which are arranged in sequence from the object side to the image side along the optical axis; The focal length f4 of the fourth lens (L4) and the focal length Fb of the second lens group (G2) satisfy the relationship: 1.25≤f4 / Fb≤2.

05.

2. The zoom lens according to claim 1, wherein: In the second lens group (G2), the seventh lens (L7) and the eighth lens (L8) form a cemented lens group.

3. The zoom lens according to claim 1, wherein: The fourth lens (L4) is a biconvex or convex-concave lens, the fifth lens (L5) is a convex-concave lens, the sixth lens (L6) is a convex-concave or concave-convex lens, the seventh lens (L7) is a biconvex lens, the eighth lens (L8) is a concave-convex or biconcave lens; and the ninth lens (L9) is a convex-concave lens.

4. The zoom lens according to claim 1, wherein: The first lens (L1) is a convex-concave lens, the second lens (L2) is a biconcave lens, and the third lens (L3) is a convex-concave or biconvex lens.

5. The zoom lens according to any one of claims 1 to 4, characterized in that: The focal length Fw at the wide-angle end and the focal length Ft at the telephoto end of the zoom lens respectively satisfy the following relationship with the focal length Fa of the first lens group (G1): -4.4≤Fa / Fw≤-3.1; -1.3≤Fa / Ft≤-0.

85.

6. The zoom lens according to any one of claims 1 to 4, characterized in that: The focal length Fw at the wide-angle end and the focal length Ft at the telephoto end of the zoom lens respectively satisfy the following relationship with the focal length Fb of the second lens group (G2): 0.2≤Fw / Fb≤0.35; 0.8≤Ft / Fb≤1.

3.

7. The zoom lens according to any one of claims 1 to 4, characterized in that: The refractive index Nd4 and the Abbe number Vd4 of the fourth lens (L4), and the refractive index Nd7 and the Abbe number Vd7 of the seventh lens (L7) respectively satisfy the following conditions: 1.4≤Nd4≤1.6; 50≤Vd4≤96; 1.4≤Nd7≤1.7; 60≤Vd7≤82.

8. The zoom lens according to any one of claims 1 to 4, characterized in that: The fifth lens (L5), the sixth lens (L6) and the ninth lens (L9) are aspherical lenses.

9. The zoom lens according to claim 8, wherein: The fifth lens (L5), the sixth lens (L6) and the ninth lens (L9) are plastic lenses.

10. The zoom lens according to any one of claims 1 to 4, characterized in that: The focal length f5 of the fifth lens (L5) and the focal length f6 of the sixth lens (L6) satisfy the following relationship: -2.3≤f5 / f6≤0.95.

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