Zoom optical system and monitoring system

Abstract

The utility model provides a zoom optical system and a monitoring system, and the zoom optical system is provided with an object side and an image side which are oppositely arranged along the direction of an optical axis. The zoom optical system comprises a first lens group with positive focal power, a second lens group with negative focal power, a third lens group with positive focal power, a fourth lens group with positive focal power, an optical filter and an image plane which are sequentially arranged from an object side to an image side, and the second lens group and the fourth lens group are movably arranged along the extension direction of the optical axis and are used for adjusting the focal length of the zoom optical system. The four-component structure is adopted, the thirteen lenses are used, and the focal power and shape matching relation of the four lens groups and the thirteen lenses are reasonably set, so that the small-size, large-target-surface, infrared and high-low-temperature confocal 4K zoom optical system is realized, and the use requirements of small distortion and clear imaging are met.

Description

Technical Field

[0001] The utility model relates to the technical field of optics, in particular to a zoom optical system and a monitoring system. Background Art

[0002] A zoom lens is a camera lens that can change its focal length within a certain range, thereby obtaining different widths of field of view, different sizes of images, and different ranges of scenery. In the field of security, zoom lenses have been widely used due to their advantages of long shooting distance and large shooting angle.

[0003] At present, the mainstream high-quality monitoring system zoom lenses on the market have the problems of low clarity, large size, and non-confocality at high and low temperatures of infrared. In addition, the target size of the mainstream photosensitive chip on the market is 1 / 1.8″ and the resolution is 4M, which is increasingly unable to meet market demand. Photosensitive chips with a target surface of 1 / 1.2″ are gradually becoming mainstream, and there are currently few types of zoom lenses on the market that can match this photosensitive chip and cannot meet market demand. Utility Model Content

[0004] The main purpose of the utility model is to propose a zoom optical system and a monitoring system, aiming to provide an infrared 4K zoom optical system with small volume, small distortion, large target surface, high and low temperature confocality.

[0005] To achieve the above-mentioned object, the utility model provides a zoom optical system, the zoom optical system has an object side and an image side which are arranged opposite to each other along the optical axis direction, the zoom optical system comprises a first lens group with positive optical power, a second lens group with negative optical power, a third lens group with positive optical power, a fourth lens group with positive optical power, a filter and an image plane which are arranged in sequence from the object side to the image side, wherein the second lens group and the fourth lens group are movably arranged along the extension direction of the optical axis for adjusting the focal length of the zoom optical system;

[0006] The first lens group includes a first lens with negative optical power, a second lens with positive optical power, and a third lens with positive optical power, which are arranged in sequence from the object side to the image side;

[0007] The second lens group includes a fourth lens with negative optical power, a fifth lens with negative optical power, and a sixth lens with positive optical power, which are arranged in sequence from the object side to the image side;

[0008] The third lens group includes a seventh lens with positive optical power, an eighth lens with positive optical power, a ninth lens with positive optical power and a tenth lens with negative optical power, which are arranged in sequence from the object side to the image side;

[0009] The fourth lens group includes an eleventh lens with negative optical power, a twelfth lens with positive optical power, and a thirteenth lens with negative optical power, which are arranged in sequence from the object side to the image side.

[0010] Optionally, the zoom optical system further includes a diaphragm disposed between the second lens group and the third lens group;

[0011] The distance from the diaphragm to the image plane is L, and the overall optical length of the zoom optical system is TTL, where 0.424 < L / TTL < 0.636.

[0012] Optionally, the first lens and the second lens are adhesively connected, the fifth lens and the sixth lens are adhesively connected, the ninth lens and the tenth lens are adhesively connected, and the eleventh lens, the twelfth lens, and the thirteenth lens are adhesively connected.

[0013] Optionally, both the fourth lens and the seventh lens are aspherical lenses.

[0014] Optionally, the aperture of the first lens is D, and the overall optical length of the zoom optical system is TTL, where 0.321 < D / TTL < 0.417.

[0015] Optionally, the zoom optical system satisfies the following conditions: 0.156 < S1 / TTL < 0.202, 0.055 < S2 / TTL < 0.071, where S1 is the relative displacement of the second lens group when the zoom optical system is in the wide-angle end position and when it is in the telephoto end position, S2 is the relative displacement of the fourth lens group when the zoom optical system is in the wide-angle end position and when it is in the telephoto end position, and TTL is the overall optical length of the zoom optical system.

[0016] Optionally, the focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the third lens group is f3, the focal length of the fourth lens group is f4, the focal length of the first lens is f11, the focal length of the second lens is f12, the focal length of the third lens is f13, the focal length of the fourth lens is f21, the focal length of the fifth lens is f22, the focal length of the sixth lens is f23, the focal length of the seventh lens is f31, the focal length of the eighth lens is f32, the focal length of the ninth lens is f33, the focal length of the tenth lens is f34, the focal length of the eleventh lens is f41, the focal length of the twelfth lens is f42, and the focal length of the thirteenth lens is f43; where

[0017] -0.601≤f11 / f1≤-0.444, 0.806≤f12 / f1≤1.091, 0.538≤f13 / f1≤0.728, 0.412≤f21 / f2≤0.557, 0.737≤f22 / f2≤0.997, -0.504≤f23 / f2≤-0.373, 0.665≤f31 / f3≤0.899, 0.564≤f32 / f3≤0.763, 0.970≤f33 / f3≤1.312, -2.185≤f34 / f3≤-1.615, -3.392≤f41 / f4≤-2.507, 5.267≤f42 / f4≤7.125, -3.548≤f43 / f1≤-2.623.

[0018] Optionally, the focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the third lens group is f3, the focal length of the fourth lens group is f4, and the focal length of the zoom optical system at the wide-angle end is f; wherein,

[0019] 0.313≤f / f1≤0.489, -1.604≤f / f2≤-1.069, 0.762≤f / f3≤1.144, 0.244≤f / f4≤0.365.

[0020] In addition, the utility model also proposes a monitoring system, the monitoring system comprises the above-mentioned zoom optical system, the zoom optical system has an object side and an image side which are arranged opposite to each other along the optical axis direction, the zoom optical system comprises a first lens group with positive optical power, a second lens group with negative optical power, a third lens group with positive optical power, a fourth lens group with positive optical power, a filter and an image plane which are arranged in sequence from the object side to the image side, wherein the second lens group and the fourth lens group are movably arranged along the extension direction of the optical axis for adjusting the focal length of the zoom optical system;

[0021] The first lens group includes a first lens with negative optical power, a second lens with positive optical power, and a third lens with positive optical power, which are arranged in sequence from the object side to the image side;

[0022] The second lens group includes a fourth lens with negative optical power, a fifth lens with negative optical power, and a sixth lens with positive optical power, which are arranged in sequence from the object side to the image side;

[0023] The third lens group includes a seventh lens with positive optical power, an eighth lens with positive optical power, a ninth lens with positive optical power and a tenth lens with negative optical power, which are arranged in sequence from the object side to the image side;

[0024] The fourth lens group includes an eleventh lens with negative optical power, a twelfth lens with positive optical power, and a thirteenth lens with negative optical power, which are arranged in sequence from the object side to the image side.

[0025] In the technical solution provided by the utility model, by setting a first lens group with positive optical focal length and a second lens group with negative optical focal length, it is ensured that light can enter the subsequent lens structure through the first lens group; by adopting a four-element structure, using thirteen lenses, and reasonably setting the optical focal length and shape matching relationship of each lens group and lens, a 4K zoom optical system with small volume, large target surface, infrared and high and low temperature confocality is realized, which meets the use requirements of small distortion and clear imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0027] Figure 1 A schematic structural diagram of an embodiment of a zoom optical system provided by the utility model;

[0028] Figure 2 for Figure 1 MTF diagram of the medium zoom optical system at the wide-angle end at 160lp / mm;

[0029] Figure 3 for Figure 1 MTF diagram of the medium zoom optical system in the middle magnification 160lp / mm frequency band;

[0030] Figure 4 for Figure 1 MTF diagram of the medium zoom optical system at the 160lp / mm frequency band at the telephoto end;

[0031] Figure 5 for Figure 1 Schematic diagram of the MTF of a medium zoom optical system at different fields of view at the wide-angle end;

[0032] Figure 6 for Figure 1 Schematic diagram of MTF of a medium zoom optical system at different fields of view at intermediate magnifications;

[0033] Figure 7 for Figure 1 Schematic diagram of the MTF of a medium zoom optical system at different fields of view at the telephoto end;

[0034] Figure 8 for Figure 1 Schematic diagram of the defocus curve of the medium zoom optical system at the wide-angle end 120lp / mm frequency band;

[0035] Fig. 9 for Figure 1 Schematic diagram of the defocus curve of the medium zoom optical system in the middle magnification 120lp / mm frequency band;

[0036] Fig.10 for Figure 1 Schematic diagram of the defocus curve of the medium zoom optical system at the telephoto end 120lp / mm frequency band;

[0037] Fig.11 for Figure 1 Field curvature distortion diagram of a medium zoom optical system at the wide angle end;

[0038] Fig.12 for Figure 1 Field curvature distortion diagram of a medium zoom optical system at intermediate magnifications;

[0039] Fig.13 for Figure 1 Field curvature distortion diagram of a medium zoom optical system at the telephoto end;

[0040] Fig.14 for Figure 1 Light fan diagram of a medium zoom optical system at the wide angle end;

[0041] Fig.15 for Figure 1 Light fan diagram of a medium zoom optical system at intermediate magnifications;

[0042] Fig.16 for Figure 1 Light fan diagram of a medium zoom optical system at the telephoto end;

[0043] Fig.17 for Figure 1 Axial aberration curve of the medium zoom optical system at the wide angle end;

[0044] Fig.18 for Figure 1 Axial aberration curve diagram of a medium zoom optical system at intermediate magnifications;

[0045] Fig.19 for Figure 1 Axial aberration curve diagram of the medium zoom optical system at the telephoto end;

[0046] Fig. 20 for Figure 1 Vertical axis chromatic aberration curve of the medium zoom optical system at the wide angle end;

[0047] Fig.21 for Figure 1Vertical axis chromatic aberration curve of the medium zoom optical system at intermediate magnifications;

[0048] Fig. 22 for Figure 1 Vertical chromatic aberration curve of a medium zoom optical system at the telephoto end.

[0049] Description of Figure Numbers:

[0050] Label name Label name 100 Zoom optical system 32 The eighth lens 1 First lens group 33 The ninth lens 11 First lens 34 Tenth lens 12 Second lens 4 The third lens group 13 The third lens 41 Eleventh lens 2 Second lens group 42 Twelfth lens 21 The fourth lens 43 Thirteenth lens 22 Fifth lens 5 Aperture 23 The sixth lens 6 Optical Filters 3 The third lens group 7 Image plane 31 Seventh lens

[0051] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0053] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0054] In addition, the descriptions of "first", "second", etc. in the present utility model are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0055] A zoom lens is a camera lens that can change its focal length within a certain range, thereby obtaining different widths of field of view, different sizes of images, and different ranges of scenery. In the field of security, zoom lenses have been widely used due to their advantages of long shooting distance and large shooting angle.

[0056] At present, the mainstream high-quality monitoring system zoom lenses on the market have the problems of low clarity, large size, and non-confocality at high and low temperatures of infrared. In addition, the target size of the mainstream photosensitive chip on the market is 1 / 1.8″ and the resolution is 4M, which is increasingly unable to meet market demand. Photosensitive chips with a target surface of 1 / 1.2″ are gradually becoming mainstream, and there are currently few types of zoom lenses on the market that can match this photosensitive chip and cannot meet market demand.

[0057] The main purpose of the utility model is to propose a zoom optical system and a monitoring system, aiming to provide an infrared 4K zoom optical system with small volume, small distortion, large target surface, high and low temperature confocality. Figures 1 to 22 This is a schematic diagram of an embodiment of the present invention.

[0058] Please refer to Figure 1 The zoom optical system 100 has an object side and an image side which are arranged opposite to each other along the optical axis direction. The zoom optical system 100 includes a first lens group 1 with positive optical power, a second lens group 2 with negative optical power, a third lens group 3 with positive optical power, a fourth lens group 4 with positive optical power, a filter 6 and an image plane 7 which are arranged in sequence from the object side to the image side. The second lens group 2 and the fourth lens group 4 are movably arranged along the extension direction of the optical axis for adjusting the focal length of the zoom optical system 100. The first lens group 1 includes a first lens 11 with negative optical power, a second lens group 2 with positive optical power, a third lens group 3 with positive optical power, a fourth lens group 4 with positive optical power, a filter 6 and an image plane 7 which are arranged in sequence from the object side to the image side. The first lens group 2 comprises a fourth lens 21 with negative optical focal length, a fifth lens 22 with negative optical focal length and a sixth lens 23 with positive optical focal length, which are arranged in sequence from the object side to the image side; the third lens group 3 comprises a seventh lens 31 with positive optical focal length, an eighth lens 32 with positive optical focal length, a ninth lens 33 with positive optical focal length and a tenth lens 34 with negative optical focal length, which are arranged in sequence from the object side to the image side; the fourth lens group 4 comprises an eleventh lens 41 with negative optical focal length, a twelfth lens 42 with positive optical focal length and a thirteenth lens 43 with negative optical focal length, which are arranged in sequence from the object side to the image side.

[0059] In the technical solution provided by the present invention, by setting a first lens group 1 with positive optical focal length and a second lens group 2 with negative optical focal length, it is ensured that light can enter the subsequent lens structure through the first lens group 1; by adopting a four-element structure, using thirteen lenses, and reasonably setting the optical focal length and shape matching relationship of each lens group and lens, a 4K zoom optical system 100 with a small volume, a large target surface, infrared and high and low temperature confocality is realized, which meets the use requirements of small distortion and clear imaging.

[0060] It should be noted that the optical filter 6 in this embodiment is provided with two filters, namely the first filter and the second filter. The first filter is used to filter infrared light and pass visible light, and the second filter is used to pass infrared light and visible light. The first filter and the second filter are both movable so that one of them can move to the optical axis and the other can move away from the optical axis. By providing two mutually switchable filters 6 to correspond to the two working modes of the zoom optical system 100, the optical system can achieve 4K image quality both during the day and at night, and the imaging quality can be further improved by reasonably adjusting the thickness of the first filter and the second filter.

[0061] Furthermore, the zoom optical system 100 also includes an aperture 5, which is arranged between the second lens group 2 and the third lens group 3. The aperture 5 limits the aperture of the light beam on the optical axis, intercepts part of the light, thereby reducing the light spot, improving the image contrast, and also plays a role in expanding the target surface and improving the image quality. According to actual conditions, adjusting the light flux of the aperture 6 helps to further improve the imaging quality. Among them, the distance from the aperture 5 to the image plane 7 is L, and the total optical length of the zoom optical system 100 is TTL, wherein 0.424<L / TTL<0.636. By limiting the position of the aperture 5, the light can pass through the zoom optical system 100 more smoothly, and the influence of aberration on the imaging quality can be corrected to a greater extent.

[0062] Furthermore, in order to allow optical components to improve the image quality of the optical system, reduce light energy loss, increase imaging clarity, protect the scale surface, and further optimize the processing flow to meet the design requirements, in this embodiment, the first lens 11 is glued to the second lens 12, the fifth lens 22 is glued to the sixth lens 23, the ninth lens 33 is glued to the tenth lens 34, and the eleventh lens 41, the twelfth lens 42 and the thirteenth lens 43 are glued. In this way, the reasonable use of glued parts and the reasonable allocation of optical focal length can well correct aberrations and achieve the effect of high and low temperature athermalization. It also effectively reduces chromatic aberration to achieve the effect of simultaneous clear confocal planes for imaging in the visible light band and the near-infrared band.

[0063] Furthermore, the fourth lens 21 and the seventh lens 31 are both aspherical lenses. It should be noted that the characteristic of aspherical lenses is that the curvature changes continuously from the center of the lens to the periphery of the lens, which is different from a spherical lens having a constant curvature from the center of the lens to the periphery of the lens.

[0064] It should be further explained that the aspheric lenses in the zoom optical system 100 provided in the embodiment of the utility model can all be plastic aspheric lenses, and lenses other than aspheric lenses can be spherical glass lenses. Among them, the two types of materials, glass and plastic, can play a role in compensating each other, so as to balance high and low temperatures and reduce the total optical length of the optical system, so that the zoom optical system 100 has the characteristics of stable high and low temperature performance, improve the environmental adaptability of the zoom optical system 100, and at the same time can better correct aberrations. By reasonably matching the temperature coefficient of the glass-plastic hybrid material, it can be ensured that the optical system has good resolution in high and low temperature environments, and the weight of the optical system can be significantly reduced. In addition, compared with glass lenses, the cost of plastic lenses also has obvious advantages, which can reduce the cost of the zoom optical system 100.

[0065] In this embodiment, specifically, please refer to Figure 1 , the first lens 11 is a concave-convex lens, and its object side surface is convex; the second lens 12 is a concave-convex lens, and its object side surface is convex; the third lens 13 is a concave-convex lens, and its object side surface is convex; the fourth lens 21 is a concave-convex lens, and its object side surface is convex; the fifth lens 22 is a biconcave lens; the sixth lens 23 is a biconvex lens; the seventh lens 31 is a biconvex lens; the eighth lens 32 is a biconvex lens; the ninth lens 33 is a biconvex lens; the tenth lens 34 is a biconcave lens; the eleventh lens 41 is a concave-convex lens, and its object side surface is convex; the twelfth lens 42 is a biconvex lens; the thirteenth lens 43 is a biconcave lens.

[0066] Further, the aperture of the first lens is D, and the total optical length of the zoom optical system 100 is TTL, wherein 0.346<D / TTL<0.55. It should be noted that the first lens has the largest aperture among all the lenses of the zoom optical system 100. By limiting the aperture of the first lens, the volume of the zoom optical system 100 is limited, which is also conducive to adjusting the optical path in the zoom optical system 100, reducing the generation of chromatic aberration and coma in the zoom optical system 100, and improving the imaging quality of the zoom optical system 100, and at the same time is conducive to achieving a large aperture effect.

[0067] Furthermore, the zoom optical system 100 satisfies the following conditions: 0.156 < S1 / TTL < 0.202, 0.055 < S2 / TTL < 0.071, where S1 is the relative displacement of the second lens group 2 when the zoom optical system 100 is in the wide-angle end position and when it is in the telephoto end position, S2 is the relative displacement of the fourth lens group 4 when the zoom optical system 100 is in the wide-angle end position and when it is in the telephoto end position, and TTL is the overall optical length of the zoom optical system 100. Among them, by controlling the moving distances of the second lens group and the fourth lens group 4, the volume of the fourth lens group 4 can be greatly reduced, and thus the volume of the zoom optical system 100 can be greatly reduced.

[0068] Furthermore, the focal length of the first lens group 1 is f1, the focal length of the second lens group 2 is f2, the focal length of the third lens group 3 is f3, the focal length of the fourth lens group 4 is f4, the focal length of the first lens 11 is f11, the focal length of the second lens 12 is f12, the focal length of the third lens 13 is f13, the focal length of the fourth lens 21 is f21, the focal length of the fifth lens 22 is f22, the focal length of the sixth lens 23 is f23, the focal length of the seventh lens 31 is f31, the focal length of the eighth lens 32 is f32, the focal length of the ninth lens 33 is f33, the focal length of the tenth lens 34 is f34, the focal length of the eleventh lens 41 is f41, the focal length of the twelfth lens 42 is f42, and the focal length of the thirteenth lens 43 is f43; where, -0.601 ≤ f11 / f1 ≤ -0.444, 0.806 ≤ f12 / f1 ≤ 1.091, 0.538 ≤ f13 / f1 ≤ 0.728, 0.412 ≤ f21 / f2 ≤ 0.557, 0.737 ≤ f22 / f2 ≤ 0.997, -0.504 ≤ f23 / f2 ≤ -0.373, 0.665 ≤ f31 / f3 ≤ 0.899, 0.564 ≤ f32 / f3 ≤ 0.763, 0.970 ≤ f33 / f3 ≤ 1.312, -2.185 ≤ f34 / f3 ≤ -1.615, -3.392 ≤ f41 / f4 ≤ -2.507, 5.267 ≤ f42 / f4 ≤ 7.125, -3.548 ≤ f43 / f1 ≤ -2.623. Among them, by defining the focal lengths of the respective lenses, a reasonable combination of the optical powers of the respective lenses can be achieved, enabling light to pass through the zoom optical system 100 more smoothly and correcting the influence of aberration on the imaging quality to a greater extent.

[0069] Further, the focal length of the first lens group 1 is f1, the focal length of the second lens group 2 is f2, the focal length of the third lens group 3 is f3, the focal length of the fourth lens group 4 is f4, and the focal length of the zoom optical system 100 at the wide-angle end is f; wherein, 0.313≤f / f1≤0.489, -1.604≤f / f2≤-1.069, 0.762≤f / f3≤1.144, 0.244≤f / f4≤0.365. By limiting the focal length of each lens group, the reasonable matching of the optical power of each lens group can be achieved, so that the light passes through the zoom optical system 100 more smoothly, and the influence of aberration on the imaging quality is corrected to a greater extent.

[0070] It is worth mentioning that the surface shape of each aspherical lens in the zoom optical system 100 described in this embodiment should satisfy the following equation:

[0071]

[0072] Among them, c is the curvature corresponding to the radius; y is the radial coordinate (its unit is the same as the lens length unit); k is the conic coefficient, and A, B, C, D, E, F, G, H... respectively represent the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, sixteenth-order, eighteenth-order... aspheric coefficients. The above parameters can be used to set the shape and size of the aspheric surface of the lens facing the object side and the image side.

[0073] Among them, when k<-1, the corresponding surface curve of the lens is a hyperbola; when k=-1, the corresponding surface curve of the lens is a parabola; when -1<k<0, the corresponding surface curve of the lens is an ellipse; when k=0, the corresponding surface curve of the lens is a circle; when k>0, the corresponding surface curve of the lens is an oblate circle.

[0074] It should be noted that the basic parameter table of the zoom optical system 100 in this embodiment is shown in Table 1, wherein the units of the curvature radius, thickness and focal length are all millimeters (mm).

[0075] Table 1

[0076]

[0077]

[0078] It should be noted that the basic parameter tables of the zoom optical system 100 at the wide-angle end, the intermediate magnification and the telephoto end in this embodiment are shown in Table 2, wherein the units of zoom 1, zoom 2, zoom 3, zoom 4 and focal length are all in millimeters (mm).

[0079] Table 2

[0080]

[0081]

[0082] In this embodiment, the aspheric coefficients of each aspheric lens in the zoom optical system 100 include: the quadratic surface coefficient k, the fourth-order aspheric coefficient A, the sixth-order aspheric coefficient B, the eighth-order aspheric coefficient C, the tenth-order aspheric coefficient D, the twelfth-order aspheric coefficient E, the fourteenth-order aspheric coefficient F, the sixteenth-order aspheric coefficient G, and the eighteenth-order aspheric coefficient H of the surface as shown in Table 3 below.

[0083] Table 3

[0084]

[0085] It is worth mentioning that the relevant dimensions of the zoom optical system 100 in this embodiment are shown in Table 4, and the units of all parameters in the table are millimeters (mm).

[0086] Table 4

[0087]

[0088]

[0089] In this embodiment, D / TTL=0.369, S1 / TTL=0.179, S2 / TTL=0.063, L / TTL=0.53, the aperture value F is between 1.66 and 1.69, the optical distortion range is between -4.73% and 1.88%, and the spectral band is between 436nm and 870nm. It can be seen that the zoom optical system 100 in this embodiment has the characteristics of small size, large target surface, small distortion, and can capture infrared radiation.

[0090] In this embodiment, the focal length of each lens, the focal length of the lens group, the ratio of the focal length at the wide-angle end to the focal length of each lens group, and the ratio of the focal length of each lens group to the focal length of each lens in the group are shown in Table 5 below, wherein all focal lengths are in millimeters.

[0091] Table 5

[0092]

[0093]

[0094] Please refer to Figures 2 to 4 , is a schematic diagram of the MTF of the zoom optical system 100 at the wide-angle end, the middle magnification and the telephoto end of the present embodiment at the 160lp / mm frequency band. It can be seen from the figure that the MTF is basically greater than 0.3 at the 160lp / mm frequency band, which basically meets the requirements of 4K imaging quality.

[0095] Please refer to Figures 5 to 7 , is a schematic diagram of the MTF of the zoom optical system 100 in different fields of view at the wide-angle end, the middle magnification and the telephoto end in this embodiment. It can be seen from the figure that the MTF is basically greater than 0.3 under different fields of view, which basically meets the requirements of 4K imaging quality.

[0096] Please refer to Figures 8 to 10 , is a schematic diagram of the defocus curve of the zoom optical system 100 in the wide-angle end, the middle magnification and the telephoto end of the embodiment under the 120lp / mm frequency band. It can be seen from the figure that the lens defocus does not exceed 10μ at the wide-angle end, the middle magnification and the telephoto end, basically reaching the state of no defocus at high and low temperatures.

[0097] Please refer to Figures 11 to 13 , is a schematic diagram of the field curvature distortion of the zoom optical system 100 at the wide-angle end, the intermediate magnification and the telephoto end in this embodiment. Different colors represent different wavelengths. The right curve of the same color is the meridian direction, and the left curve is the sagittal field curvature. From the figure, the sagittal field curvature of this lens at the wide-angle end is no more than 20μm, indicating that this lens can better correct chromatic aberration at the wide-angle end. Another curve in the figure is the distortion curve of the system. The distortion does not affect the clarity of the system, but it will cause the image deformation of the system. The optical distortion of this system at the telephoto end is less than 5%.

[0098] Please refer to Figure 14-16 , are the light fan diagrams of the zoom optical system 100 in this embodiment at the wide-angle end, the intermediate magnification and the telephoto end respectively. In the figure, the horizontal axis is the normalized light beam aperture, and the vertical axis is the vertical axis aberration. Ideally, each curve should completely coincide with the horizontal axis, and at this time all light rays in the field of view are focused on the same point on the image plane 5; the vertical axis in the image can also be expressed as the maximum dispersion range of the light beam on the ideal image plane. The light fan diagram can not only reflect the monochromatic aberrations of different wavelengths, but also indicate the size of the vertical axis chromatic aberration. As can be seen from the figure, the zoom optical system 100 is relatively close to the horizontal axis at each wavelength in each field of view, indicating that the vertical axis aberration of each wavelength is well corrected. In addition, the curves of each color are not obviously dispersed, indicating that the zoom optical system 100 also has good correction for chromatic aberration, ensuring the imaging requirement of the zoom optical system 100 to form clear images in the full band.

[0099] Please refer to Figure 17-Figure 19, are axial aberration curves of the zoom optical system 100 at the wide-angle end, intermediate magnification and telephoto end in this embodiment. The vertical direction represents the normalization of the aperture, 0 represents the optical axis, and the vertex in the vertical axis direction represents the maximum pupil radius; the horizontal direction represents the offset relative to the main wavelength, in millimeters (mm). It can be seen from the figure that when the zoom optical system 100 is at the wide-angle end, the axial aberrations of different wavelengths are basically controlled within the range of (-0.01mm, +0.035mm); when the zoom optical system 100 is at the intermediate magnification, the axial aberrations of different wavelengths are basically controlled within the range of (-0.05mm, +0.02mm); when the zoom optical system 100 is at the telephoto end, the axial aberrations of different wavelengths are basically controlled within the range of (-0.02mm, +0.04mm), indicating that the axial aberrations of the zoom optical system 100 at the wide-angle end, intermediate magnification and telephoto end are well controlled, and can meet the full-band wide spectrum application requirements.

[0100] Please refer to Figure 20-Figure 22 , are vertical chromatic aberration curves of the zoom optical system 100 at the wide-angle end, the intermediate magnification and the telephoto end in this embodiment. It can be seen from the figure that when the zoom optical system 100 is at the wide-angle end, the vertical chromatic aberration of different wavelengths is controlled within the range of (-2μm, +8μm); when the zoom optical system 100 is at the intermediate magnification, the vertical chromatic aberration of different wavelengths is controlled within the range of (-2μm, +3μm); when the zoom optical system 100 is at the telephoto end, the vertical chromatic aberration of different wavelengths is controlled within the range of (-4.5μm, +0.7μm), indicating that the vertical chromatic aberration of the zoom optical system 100 at the wide-angle end, the intermediate magnification and the telephoto end is well controlled, and can meet the full-band wide spectrum application requirements.

[0101] The utility model also proposes a monitoring system, which includes the above-mentioned zoom optical system 100. Since the monitoring system includes the zoom optical system 100, the specific structure of the zoom optical system 100 refers to the above-mentioned embodiment. Since the zoom optical system 100 of the monitoring system adopts all the technical solutions of all the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0102] The above description is only an optional embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A zoom optical system, characterized in that: The zoom optical system has an object side and an image side that are oppositely arranged along the optical axis direction. The zoom optical system includes a first lens group with a positive optical power, a second lens group with a negative optical power, a third lens group with a positive optical power, a fourth lens group with a positive optical power, a filter, and an image plane, which are arranged in sequence from the object side to the image side. Among them, the second lens group and the fourth lens group are movably arranged along the optical axis extension direction to adjust the focal length of the zoom optical system; The first lens group includes a first lens with a negative optical power, a second lens with a positive optical power, and a third lens with a positive optical power, which are arranged in sequence from the object side to the image side; The second lens group includes a fourth lens with a negative optical power, a fifth lens with a negative optical power, and a sixth lens with a positive optical power, which are arranged in sequence from the object side to the image side; The third lens group includes a seventh lens with a positive optical power, an eighth lens with a positive optical power, a ninth lens with a positive optical power, and a tenth lens with a negative optical power, which are arranged in sequence from the object side to the image side; The fourth lens group includes an eleventh lens with a negative optical power, a twelfth lens with a positive optical power, and a thirteenth lens with a negative optical power, which are arranged in sequence from the object side to the image side.

2. The zoom optical system according to claim 1, wherein: The zoom optical system further includes a diaphragm, and the diaphragm is arranged between the second lens group and the third lens group; The distance from the diaphragm to the image plane is L, and the overall optical length of the zoom optical system is TTL, where 0.424 < L / TTL < 0.

636.

3. The zoom optical system according to claim 1, wherein: The first lens and the second lens are adhesively connected, the fifth lens and the sixth lens are adhesively connected, the ninth lens and the tenth lens are adhesively connected, and the eleventh lens, the twelfth lens, and the thirteenth lens are adhesively connected.

4. The zoom optical system according to claim 1, wherein: Both the fourth lens and the seventh lens are aspherical lenses.

5. The zoom optical system according to claim 1, wherein: The aperture of the first lens is D, and the overall optical length of the zoom optical system is TTL, where 0.321 < D / TTL < 0.

417.

6. The zoom optical system according to claim 1, wherein: The zoom optical system satisfies the following conditions: 0.156 < S1 / TTL < 0.202, 0.055 < S2 / TTL < 0.071, where S1 is the relative displacement of the second lens group when the zoom optical system is in the wide-angle end position and when the zoom optical system is in the telephoto end position, S2 is the relative displacement of the fourth lens group when the zoom optical system is in the wide-angle end position and when the zoom optical system is in the telephoto end position, and TTL is the overall optical length of the zoom optical system.

7. The zoom optical system according to claim 1, wherein: The focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the third lens group is f3, the focal length of the fourth lens group is f4, the focal length of the first lens is f11, the focal length of the second lens is f12, the focal length of the third lens is f13, the focal length of the fourth lens is f21, the focal length of the fifth lens is f22, the focal length of the sixth lens is f23, the focal length of the seventh lens is f31, the focal length of the eighth lens is f32, the focal length of the ninth lens is f33, the focal length of the tenth lens is f34, the focal length of the eleventh lens is f41, the focal length of the twelfth lens is f42, and the focal length of the thirteenth lens is f43; wherein, -0.601≤f11 / f1≤-0.444, 0.806≤f12 / f1≤1.091, 0.538≤f13 / f1≤0.728, 0.412≤f21 / f2≤0.557, 0.737≤f22 / f2≤0.997, -0.504≤f23 / f2≤-0.373, 0.665≤f31 / f3≤0.899, 0.564≤f32 / f3≤0.763, 0.970≤f33 / f3≤1.312, -2.185≤f34 / f3≤-1.615, -3.392≤f41 / f4≤-2.507, 5.267≤f42 / f4≤7.125, -3.548≤f43 / f1≤-2.

623.

8. The zoom optical system according to claim 1, wherein: The focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the third lens group is f3, the focal length of the fourth lens group is f4, and the focal length of the zoom optical system at the wide-angle end is f; wherein, 0.313≤f / f1≤0.489, -1.604≤f / f2≤-1.069, 0.762≤f / f3≤1.144, 0.244≤f / f4≤0.

365.

9. A monitoring system, characterized in that: Comprising the zoom optical system as described in any one of claims 1-8.

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