Zoom lens and imaging device

Abstract

The application discloses a zoom lens and an imaging device, the zoom lens comprising a lens barrel, a light source and a lens group, the lens group comprising a fixed group, a zoom group, a compensation group and an image plane arranged in sequence from an object side to an image side, the zoom group and the compensation group moving along the optical axis direction, the compensation group being used for adjusting the imaging distance when the zoom group zooms, the fixed group comprising a first cylindrical lens and a second free-form surface lens, the first cylindrical lens shaping the light beam projected by the light source in the x direction, and the second free-form surface lens shaping the light beam projected by the first cylindrical lens in the y direction, so that the zoom lens has a strong shaping effect, can stretch the light rays in two directions, and maximally compresses the volume, and the free-form surface has high surface type freedom degree, can effectively correct the light aberration, and increases the definition around the final light spot, so as to solve the problems of poor aberration correction ability, large volume and low zoom ratio of the existing laser lens.

Description

Technical Field

[0001] This invention relates to the field of optical system design technology, and in particular to a zoom lens and imaging device for use in outdoor monitoring systems. Background Technology

[0002] With the rapid development of night vision zoom lens technology, the illumination of the zoom lens's field of view has become increasingly important, especially with the ever-increasing demand for infrared zoom illumination at night. Currently, the common solution is to use laser fiber as the light source, which, in conjunction with the zoom lens, allows for adjustments to the emitted light angle, resulting in a uniform light spot with clear boundaries. To best adapt to the lighting of the captured image, sometimes the shape of the illumination spot is required to be elliptical or rectangular. However, most fiber optic ports on the market are circular or square, which means that the laser beam needs to be shaped.

[0003] The common practice is to use cylindrical lenses to shape the light beam, stretching the light rays in one direction. The originally circular light spot will be elongated into an ellipse. However, cylindrical lenses have large aberrations and can only shape the light in one direction. When the total length and maximum aperture of the lens are limited, the zoom ratio of the lens cannot be maximized, resulting in poor aberration correction capabilities, large size, and low zoom ratio of existing laser lenses. Summary of the Invention

[0004] The main objective of this invention is to provide a zoom lens that addresses the technical problems of existing laser lenses, such as poor aberration correction capabilities, large size, and low zoom ratio.

[0005] To achieve the above objectives, the present invention provides a zoom lens having an object side and an image side disposed opposite to each other along the optical axis, the zoom lens comprising:

[0006] Lens tube;

[0007] A light source is disposed on the side of the object; and,

[0008] A lens group, comprising a fixed group, a zoom group, a compensation group, and an image plane arranged sequentially from the object side to the image side, wherein the fixed group is fixedly mounted on the lens barrel, the zoom group and the compensation group are movably mounted on the lens barrel along the optical axis, the zoom group and the compensation group move together along the optical axis, and the compensation group is used to adjust the imaging distance when the zoom group zooms;

[0009] The fixed assembly includes a first cylindrical lens and a second freeform surface lens arranged sequentially from the object side to the image side. The first cylindrical lens is used to shape the light beam projected from the light source in the x-direction, and the second freeform surface lens is used to shape the light beam projected from the first cylindrical lens in the y-direction.

[0010] Optionally, the light source is set as a fiber optic light source.

[0011] Optionally, the optical power of the fixed group is positive, and the first cylindrical lens, the second freeform lens, and the fixed group satisfy the following conditions:

[0012] 0.8 < f1x / F1x < 1, and 6.7 < f2x / F1x < 9.0, f2y = F1y;

[0013] Where, F1x is the focal length of the fixed group in the x direction, F1y is the focal length of the fixed group in the y direction, f1x is the focal length of the first cylindrical lens in the x direction, f2x is the focal length of the second freeform lens in the x direction, and f2y is the focal length of the second freeform lens in the y direction.

[0014] Optionally, the optical power of the first cylindrical lens is positive, and the object side surface of the first cylindrical lens is convex, and its image side surface is convex;

[0015] The optical power of the second freeform lens is positive, and the object side surface of the second freeform lens is concave, and its image side surface is convex.

[0016] Optionally, the surface shape of the object side surface of the second freeform lens satisfies the following conditions:

[0017]

[0018] Where, c x is the radius of curvature in the x direction, c y is the radius of curvature in the y direction, k x is the conic coefficient in the x direction, k y is the conic coefficient in the y direction.

[0019] Optionally, the optical power of the zoom group is negative, the zoom group includes a third biconcave lens and a fourth biconcave lens arranged in sequence from the object side to the image side, both the third biconcave lens and the fourth biconcave lens are spherical lenses, and the third biconcave lens, the fourth biconcave lens, and the zoom group satisfy the following conditions:

[0020] 1.9 < f3 / F2 < 2.7, and 2.1 < f4 / F2 < 2.9;

[0021] Where, F2 is the focal length of the zoom group, f3 is the focal length of the third biconcave lens, and f4 is the focal length of the fourth biconcave lens.

[0022] Optionally, the optical powers of both the third biconcave lens and the fourth biconcave lens are negative, and both the object side surfaces and the image side surfaces of the third biconcave lens and the fourth biconcave lens are also concave.

[0023] Optionally, the optical power of the compensating group is positive. The compensating group includes a fifth meniscus lens, a sixth meniscus lens, and a seventh biconvex lens arranged in sequence from the object side to the image side. The fifth meniscus lens, the sixth meniscus lens, and the seventh biconvex lens are all spherical lenses. The fifth meniscus lens, the sixth meniscus lens, the seventh biconvex lens, and the compensating group satisfy the following conditions:

[0024] 2.7 < f5 / F3 < 3.8, and 2.7 < f6 / F3 < 3.6, and 2.2 < f7 / F3 < 3.0;

[0025] where F3 is the focal length of the compensating group, f5 is the focal length of the fifth meniscus lens, f6 is the focal length of the sixth meniscus lens, and f7 is the focal length of the seventh biconvex lens.

[0026] Optionally, the optical power of the fifth meniscus lens is positive, and the object side surface of the fifth meniscus lens is concave, and its image side surface is convex;

[0027] The optical power of the sixth meniscus lens is positive, and the object side surface of the sixth meniscus lens is concave, and its image side surface is convex;

[0028] The optical power of the seventh biconvex lens is positive, and the object side surface of the seventh biconvex lens is convex, and its image side surface is convex.

[0029] An imaging device, the imaging device includes the zoom lens according to the above technical solution.

[0030] In the technical solution provided by this invention, the fixed assembly is fixedly installed on the lens barrel, and the zoom assembly and the compensation assembly are movably installed on the lens barrel along the optical axis. The fixed assembly includes a first cylindrical lens and a second freeform surface lens arranged sequentially from the object side to the image side. The first cylindrical lens and the second freeform surface lens are used to focus and shape the incident light beam, so that the light beam is shaped into a light beam with a desired shape. The zoom assembly is used for zooming, and the compensation assembly is used to adjust the imaging distance when the zoom assembly zooms. The zoom assembly and the compensation assembly move together along the optical axis so that the zoom lens zooms from the wide-angle end to the telephoto end, and the compensation assembly is driven by an external force. The zoom lens moves along the optical axis in accordance with the position, imaging wavelength, and imaging object distance of the zoom group, ensuring that the imaging surface remains clear during zooming. The first cylindrical lens shapes the light beam projected from the light source in the x-direction, and the second freeform surface lens shapes the light beam projected from the first cylindrical lens in the y-direction. This gives the zoom lens a strong shaping effect, allowing it to stretch light in both directions while maximizing volume compression. Furthermore, the freeform surface has a high degree of freedom in shape, effectively correcting light aberrations and increasing the clarity around the final light spot. This addresses the problems of poor aberration correction capability, large size, and low zoom ratio of existing laser lenses. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0032] Figure 1 A schematic diagram of the cross-sectional structure of the zoom lens provided by the present invention;

[0033] Figure 2 for Figure 1 A schematic diagram of the light source in the image;

[0034] Figure 3 for Figure 1 A schematic diagram of the zoom lens in the wide-angle position;

[0035] Figure 4 for Figure 1 A schematic diagram of the structure of a zoom lens at the intermediate magnification.

[0036] Figure 5 for Figure 1 A schematic diagram of the zoom lens in the telephoto end;

[0037] Figure 6 for Figure 3 A schematic diagram of the incoherent irradiance of a zoom lens at the wide-angle end;

[0038] Figure 7 for Figure 4 A schematic diagram of the incoherent irradiance of a zoom lens at the wide-angle end;

[0039] Figure 8 for Figure 5 A schematic diagram of the incoherent irradiance of a zoom lens at an intermediate magnification.

[0040] Explanation of icon numbers:

[0041] label name label name 10 light source 4 Fourth biconcave lens 20 Fixed group 40 Compensation Group 1 First cylindrical lens 5 Fifth Crescent Lens 2 Second freeform surface lens 6 Sixth Crescent Lens 30 Variable multiplication group 7 Seventh biconvex lens 3 Third biconcave lens

[0042] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0044] It should be noted that if the embodiments of the present invention involve directional indication, the directional indication is only used to explain the relative positional relationship and movement of the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0045] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Moreover, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0046] With the rapid development of night vision zoom lens technology, the illumination of the zoom lens's field of view has become increasingly important, especially with the ever-increasing demand for infrared zoom illumination at night. Currently, the common solution is to use laser fiber as the light source, which, in conjunction with the zoom lens, allows for adjustment of the emitted light angle, resulting in a uniform light spot with clear boundaries. To best adapt to the lighting of the captured image, sometimes the shape of the illumination spot is required to be elliptical or rectangular. However, most fiber optic ports on the market are circular or square, meaning that laser beam shaping is necessary. The common practice is to use cylindrical lenses to shape the beam, stretching the light in one direction, elongating the originally circular spot into an ellipse. However, cylindrical lenses have significant aberrations and can only shape in one direction. When the total length and maximum aperture of the lens are limited, the zoom ratio cannot be maximized, resulting in poor aberration correction capabilities, large size, and low zoom ratio of existing laser lenses.

[0047] This invention provides a zoom lens designed to improve upon the technical problems of existing laser lenses, such as poor aberration correction capability, large size, and low zoom ratio. Please refer to [reference needed]. Figures 1 to 8 The attached figure shows a specific embodiment of the zoom lens.

[0048] Figures 1 to 8 This is a first embodiment of the zoom lens provided by the present invention.

[0049] Please refer to Figures 1 to 5 The zoom lens has an object side and an image side arranged opposite each other along the optical axis. The zoom lens includes a lens barrel (not shown in the figure), a light source 10, and a lens group. The light source 10 is located on the object side. The lens group includes a fixed group 20, a zoom group 30, a compensation group 40, and an image plane arranged sequentially from the object side to the image side. The fixed group 20 is fixedly installed on the lens barrel. The zoom group 30 and the compensation group 40 are movably installed on the lens barrel along the optical axis. The zoom group 30 and the compensation group 40 move together along the optical axis. The compensation group 40 is used to adjust the imaging distance when the zoom group 30 zooms. The fixed group 20 includes a first cylindrical lens 1 and a second freeform surface lens 2 arranged sequentially from the object side to the image side. The first cylindrical lens 1 is used to shape the light beam projected from the light source 10 in the x-direction, and the second freeform surface lens 2 is used to shape the light beam projected from the first cylindrical lens 1 in the y-direction.

[0050] It should be noted that both the zoom group 30 and the compensation group 40 can be driven by an external force to move along the optical axis. The external force can be driven by a drive motor or manually adjusted, which is not limited here.

[0051] It should be noted that the angle between the upper ray and the lower ray emitted from the light source is defined as the divergence angle. The divergence angle can be changed by the coordinated movement of the zoom group 30 and the compensation group 40. When the zoom group 30 is close to the telephoto end (T end) of the light source 10, the zoom lens has the maximum focal length and the minimum divergence angle. When the zoom group 30 is close to the image plane and moves towards the wide-angle end (W end), the focal length of the zoom lens gradually decreases and the divergence angle gradually increases.

[0052] In the technical solution provided by this invention, the fixed assembly 20 is fixedly installed on the lens barrel, and the zoom assembly 30 and the compensation assembly 40 are movably installed on the lens barrel along the optical axis. The fixed assembly 20 includes a first cylindrical lens 1 and a second freeform surface lens 2 arranged sequentially from the object side to the image side. The first cylindrical lens 1 and the second freeform surface lens 2 are used to focus and shape the incident light beam, so that the light beam is shaped into a light beam with a desired shape. The zoom assembly 30 is used for zooming, and the compensation assembly 40 is used to adjust the imaging distance when the zoom assembly 30 zooms. The zoom assembly 30 and the compensation assembly 40 move together along the optical axis so that the zoom lens zooms from the wide-angle end to the telephoto end, and the compensation assembly 40... Driven by an external force, the zoom group 40 moves along the optical axis to focus in accordance with the position, imaging wavelength, and imaging object distance of the zoom group 30, so that the zoom lens keeps the imaging surface clear during the zoom process. The first cylindrical lens 1 shapes the light beam projected from the light source 10 in the x-direction, and the second freeform surface lens 2 shapes the light beam projected from the first cylindrical lens 1 in the y-direction, so that the zoom lens has a strong shaping effect, can stretch the light in two directions, and compress the volume to the maximum extent. Moreover, the freeform surface has a high degree of freedom, which can effectively correct light aberrations and increase the clarity around the final light spot, so as to solve the problems of poor aberration correction capability, large size, and low zoom ratio of existing laser lenses.

[0053] Specifically, in this embodiment, the light source 10 is configured as an optical fiber light source 10. Because the light intensity distribution at the fiber end face is uniform and the boundaries are clear, the imaged light spot is also uniform and has clear boundaries. More specifically, the optical fiber port of the optical fiber light source 10 is configured as SMA905, with a port diameter of 0.28 mm and a numerical aperture NA = 0.22. After the light beam emitted from the optical fiber light source 10 passes through the lens group, the light spot ultimately transmitted onto the image plane is a magnified elliptical light spot with a uniformity of over 90% and relatively clear boundaries.

[0054] Specifically, in this embodiment, the optical power of the fixed group 20 is positive, and the first cylindrical lens 1, the second free-form surface lens 2, and the fixed group 20 satisfy the following conditions: 0.8 < f1x / F1x < 1, and 6.7 < f2x / F1x < 9.0, f2y = F1y; where, F1x is the focal length of the fixed group 20 in the x direction, F1y is the focal length of the fixed group 20 in the y direction, f1x is the focal length of the first cylindrical lens 1 in the x direction, f2x is the focal length of the second free-form surface lens 2 in the x direction, and f2y is the focal length of the second free-form surface lens 2 in the y direction. It should be noted that the optical power is equal to the difference between the image-side beam convergence and the object-side beam convergence, which characterizes the ability of the optical system to deflect light rays.

[0055] Specifically, in this embodiment, the optical power of the first cylindrical lens 1 is positive, and the object side surface of the first cylindrical lens 1 is convex, and its image side surface is convex; the optical power of the second free-form surface lens 2 is positive, and the object side surface of the second free-form surface lens 2 is concave, and its image side surface is convex.

[0056] Specifically, since the object side surface of the second free-form surface lens 2 is a free-form surface, in order to enable this free-form surface to be transmitted in the required transmission direction, the surface shape of the object side surface of the second free-form surface lens 2 satisfies the following conditions: where, c x is the radius of curvature in the X direction, that is, c x = 1 / Rx, c y is the radius of curvature in the Y direction, that is, c y = 1 / Ry, k x is the conic coefficient in the X direction, k y is the conic coefficient in the Y direction.

[0057] Specifically, in this embodiment, the optical power of the zoom group 30 is negative, and the zoom group 30 includes a third biconcave lens 3 and a fourth biconcave lens 4 arranged in sequence from the object side to the image side. Both the third biconcave lens 3 and the fourth biconcave lens 4 are spherical lenses. The third biconcave lens 3, the fourth biconcave lens 4, and the zoom group 30 satisfy the following conditions: 1.9 < f3 / F2 < 2.7, and 2.1 < f4 / F2 < 2.9; where, F2 is the focal length of the zoom group 30, f3 is the focal length of the third biconcave lens 3, and f4 is the focal length of the fourth biconcave lens 4.

[0058] Specifically, in this embodiment, the optical powers of both the third biconcave lens 3 and the fourth biconcave lens 4 are negative, and both the object side surfaces and the image side surfaces of the third biconcave lens 3 and the fourth biconcave lens 4 are also concave.

[0059] Specifically, since distortion affects the uniformity of the illuminance distribution, in this embodiment, the optical power of the compensation group 40 is positive. The compensation group 40 includes a fifth meniscus lens 5, a sixth meniscus lens 6, and a seventh double convex lens 7 arranged in sequence from the object side to the image side. The fifth meniscus lens 5, the sixth meniscus lens 6, and the seventh double convex lens 7 are all spherical lenses. The fifth meniscus lens 5, the sixth meniscus lens 6, the seventh double convex lens 7, and the compensation group 40 satisfy the following conditions: 2.7 < f5 / F3 < 3.8, 2.7 < f6 / F3 < 3.6, and 2.2 < f7 / F3 < 3.0; where F3 is the focal length of the compensation group 40, f5 is the focal length of the fifth meniscus lens 5, f6 is the focal length of the sixth meniscus lens 6, and f7 is the focal length of the seventh double convex lens 7.

[0060] Specifically, in this embodiment, the optical power of the fifth meniscus lens 5 is positive, and the object side surface of the fifth meniscus lens 5 is concave, and its image side surface is convex; the optical power of the sixth meniscus lens 6 is positive, and the object side surface of the sixth meniscus lens 6 is concave, and its image side surface is convex; the optical power of the seventh double convex lens 7 is positive, and the object side surface of the seventh double convex lens 7 is convex, and its image side surface is convex. Distortion is effectively corrected.

[0061] Thus, by reasonably designing the optical parameters and materials of each lens, the zoom lens can ensure clear resolution without refocusing in extreme environments. The system fully considers the matching of the changes in the refractive index and Abbe number of various lens materials at high and low temperatures with the changes in the surface shape and air gap, achieving a positive and negative combination of the changes in various factors such as high and low temperatures and humidity, and ensuring the synchronization and clarity of the image plane in high and low temperature and different humidity environments. By reasonably distributing the optical power of the lenses, adjusting the glass shape and material combination, chromatic aberration and secondary spectrum are effectively eliminated, and spherical aberration, coma, astigmatism, etc. on each lens are compensated and offset from each other to achieve the effect of clear imaging. Spherical lenses are used to reduce costs, with lower assembly sensitivity and higher finished product yield while ensuring image quality and reliability.

[0062] Specifically, the imaging surface can be understood as the surface of the photosensitive chip facing the object side, that is, it can be the surface of a CCD or CMOS imaging element, etc. It can be understood that the light carrying the information of the photographed object can pass through the fixed group 20, the variable magnification group 30, and the compensation group 40 in sequence and finally form an image on the imaging surface.

[0063] Specifically, in this embodiment, the parameters of the zoom lens are as follows:

[0064] The focal length at the wide-angle end fw = 0.687 mm, and the focal length at the telephoto end ft = 81.36 mm; the aperture number at the wide-angle end Fno w=2.22, telephoto aperture number Fno T =2.22; Horizontal field angle (FOVH) at the wide-angle end w =20°, field of view (FOVH) at the far end T =0.15°; optical distortion range is between -1% and 3.5%; the total optical length of the zoom lens is TTL = 90mm.

[0065] Specifically, in this embodiment, the refractive index, radius of curvature, and thickness interval of the lens material are shown in the table below:

[0066] Table 1 Lens Parameters

[0067] # Type Radius-Y Thickness Material Conic-Y Radius-X conic-X 0 STANDARD unlimited 2.48E+00 1.00E+00 0.00E+00 0.00E+00 1 BICONICX unlimited 1.88E+00 1.76,26.6 0.00E+00 6.62E+00 0.00E+00 2 BICONICX unlimited 2.35E+00 0.00E+00 -3.51E+00 0.00E+00 3 BICONICX -5.55E+01 1.40E+00 1.85,40.1 9.90E+01 -4.75E+00 1.86E+00 4 STANDARD -4.53E+00 4.04E+01 -4.77E-01 0.00E+00 0.00E+00 5 STANDARD -7.05E+00 1.49E+00 1.62,58.1 0.00E+00 0.00E+00 0.00E+00 6 STANDARD 1.01E+01 2.24E+00 0.00E+00 0.00E+00 0.00E+00 7 STANDARD -4.67E+00 1.54E+00 1.64,55.4 0.00E+00 0.00E+00 0.00E+00 8 STANDARD 1.36E+02 1.28E+00 0.00E+00 0.00E+00 0.00E+00 9 STANDARD -3.87E+01 5.19E+00 1.49,70.4 0.00E+00 0.00E+00 0.00E+00 10 STANDARD -2.49E+01 8.11E-02 0.00E+00 0.00E+00 0.00E+00 11 STANDARD -9.91E+01 5.04E+00 1.49.70.4 0.00E+00 0.00E+00 0.00E+00 12 STANDARD -3.78E+01 9.76E-02 0.00E+00 0.00E+00 0.00E+00 13 STANDARD 4.52E+02 5.04E+00 1.65,33.8 0.00E+00 0.00E+00 0.00E+00 14 STANDARD -7.68E+01 3.00E+04 0.00E+00 0.00E+00 0.00E+00 15 STANDARD unlimited 0.00E+00 0.00E+00 0.00E+00 0.00E+00

[0068] In this embodiment, please refer to Figures 3 to 5 The diagram shows the structure of the zoom lens when it is at the wide-angle end, the intermediate magnification, and the telephoto end; wherein, the intermediate magnification can be understood as the position diagram of each lens group in the zoom lens when the zoom lens is between the wide-angle end and the telephoto end.

[0069] Figures 6 to 8 The diagrams show the incoherent irradiance of the zoom lens at the wide-angle, intermediate magnification, and telephoto ends, respectively.

[0070] As can be seen from the above figures, the zoom lens in this embodiment can achieve good correction of spherical aberration, field curvature, and distortion at the intermediate magnification, wide-angle end, and telephoto end, thereby producing clear images.

[0071] In summary, the zoom lens of this invention adopts a three-group structure of "positive-negative-positive", consisting of a fixed group 20, a zoom group 30, and a compensation group 40. As the zoom group 30 moves accordingly, the focal length changes. The compensation group 40 is used for focusing. The focal length can vary between 0.687mm at the wide-angle end and 81.36mm at the telephoto end. The horizontal shooting angle at the wide-angle end is >20°, and the optical distortion at both the wide-angle and telephoto ends is within -1% to 3.5%. The total optical length is controlled within 90mm, resulting in a small size, good optical effect, and large zoom ratio. Furthermore, the zoom lens contains five glass spherical lenses, which fully guarantee good optical performance.

[0072] Furthermore, the present invention also provides an imaging device, which includes the zoom lens described in the above-described technical solutions. The specific structure of the zoom lens is as described in the above embodiments. Since the zoom lens of this imaging device adopts all the technical solutions of all the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be elaborated further here.

[0073] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A zoom lens, characterized in that, The zoom lens has an object side and an image side disposed oppositely along the optical axis direction, and the zoom lens includes: A lens barrel; A light source disposed on the object side; and, A lens group, the lens group includes a fixed group, a variable magnification group, a compensation group, and an image plane arranged in sequence from the object side to the image side, wherein the fixed group is fixedly installed on the lens barrel, the variable magnification group and the compensation group are movably installed on the lens barrel along the optical axis direction, the variable magnification group and the compensation group move cooperatively along the optical axis direction, and the compensation group is used to adjust the imaging distance when the variable magnification group changes magnification; Wherein, the fixed group includes a first cylindrical lens and a second free-form surface lens arranged in sequence from the object side to the image side, the first cylindrical lens is used to shape the light beam projected by the light source in the x direction, and the second free-form surface lens is used to shape the light beam projected by the first cylindrical lens in the y direction; The optical power of the fixed group is positive, the optical power of the first cylindrical lens is positive, and the optical power of the second free-form surface lens is positive; The optical power of the variable magnification group is negative, the variable magnification group includes a third biconcave lens and a fourth biconcave lens arranged in sequence from the object side to the image side, and the optical powers of the third biconcave lens and the fourth biconcave lens are both negative; The optical power of the compensation group is positive, the compensation group includes a fifth meniscus lens, a sixth meniscus lens, and a seventh biconvex lens arranged in sequence from the object side to the image side, the optical power of the fifth meniscus lens is positive, the optical power of the sixth meniscus lens is positive, and the optical power of the seventh biconvex lens is positive.

2. The zoom lens as described in claim 1, characterized in that, The light source is set as a fiber optic light source.

3. The zoom lens as described in claim 1, characterized in that, The first cylindrical lens, the second free-form surface lens, and the fixed group satisfy the following conditions: 0.8 < f1x / F1x < 1, and 6.7 < f2x / F1x < 9.0, f2y = F1y; Wherein, F1x is the x-direction focal length of the fixed group, F1y is the y-direction focal length of the fixed group, f1x is the x-direction focal length of the first cylindrical lens, f2x is the x-direction focal length of the second free-form surface lens, and f2y is the y-direction focal length of the second free-form surface lens.

4. The zoom lens as described in claim 3, characterized in that, The object side surface of the first cylindrical lens is convex, and its image side surface is convex; The object side surface of the second free-form surface lens is concave, and its image side surface is convex.

5. The zoom lens as described in claim 4, characterized in that, The surface shape of the object side surface of the second free-form surface lens satisfies the following conditions: Among them, c x Let c be the radius of curvature in the x-direction. y Let k be the radius of curvature in the y-direction. x k is the conic coefficient in the x-direction. y y is the conic coefficient in the y-direction.

6. The zoom lens as described in claim 1, characterized in that, Both the third biconcave lens and the fourth biconcave lens are spherical lenses, and the third biconcave lens, the fourth biconcave lens, and the variable magnification group satisfy the following conditions: 1.9 < f3 / F2 < 2.7, and 2.1 < f4 / F2 < 2.9; Wherein, F2 is the focal length of the variable magnification group, f3 is the focal length of the third biconcave lens, and f4 is the focal length of the fourth biconcave lens.

7. The zoom lens as described in claim 6, characterized in that, The object side surfaces and the image side surfaces of the third biconcave lens and the fourth biconcave lens are also both concave.

8. The zoom lens as described in claim 1, characterized in that, The fifth meniscus lens, the sixth meniscus lens, and the seventh biconvex lens are all spherical lenses, and the fifth meniscus lens, the sixth meniscus lens, the seventh biconvex lens, and the compensation group satisfy the following conditions: 2.7 < f5 / F3 < 3.8, and 2.7 < f6 / F3 < 3.6, and 2.2 < f7 / F3 < 3.0; where F3 is the focal length of the compensation group, f5 is the focal length of the fifth meniscus lens, f6 is the focal length of the sixth meniscus lens, and f7 is the focal length of the seventh biconvex lens.

9. The zoom lens as described in claim 8, characterized in that, The object side of the fifth meniscus lens is concave, and its image side is convex; The object side of the sixth meniscus lens is concave, and its image side is convex; The object side of the seventh biconvex lens is convex, and its image side is convex.

10. An imaging device, characterized in that, The imaging device includes the zoom lens according to any one of claims 1 to 9.

Images