High-definition visible light television continuous zooming optical system

Abstract

The invention relates to a continuous zooming optical system of a high-definition visible light television. The continuous zooming optical system comprises a front fixed group, a zooming group, a compensation group and a rear fixed group which are sequentially arranged on an optical axis along a light propagation direction, a fast reflector FSM and a plane reflex reflector II are arranged in the rear fixing group, and the normal of the fast reflector FSM and the normal of the plane reflex reflector II form an included angle of 45 degrees with the optical axis, so that the optical system is of a U-shaped structure, and the axial length of the system is effectively shortened; the emergent light beams of the third meniscus positive lens of the rear fixing group are parallel light beams, so that the MTF at the edge field of view of the optical system cannot be reduced in the swinging process of the fast reflecting mirror, and the problems that the stability precision becomes poor and the definition of the imaging system is reduced due to vibration of a carrier are solved. The system stability precision in the airborne photoelectric system is effectively improved, and meanwhile, the imaging system is kept to perform clear imaging on a target all the time.

Description

Technical Field

[0001] The invention relates to the field of visible light zoom optical systems, and in particular to a high-definition visible light television continuous zoom optical system. Background Art

[0002] Visible light cameras are key sensors for airborne optoelectronic equipment, used for wide-area search, target identification, target tracking, target guidance and other technical tasks for regional targets during the day. With the development of technology, optoelectronic equipment has increasingly higher requirements for visible light cameras, which not only require clear imaging of targets under different fields of view, but also require visible light cameras to be small in size and light in weight.

[0003] Single-field visible light television continuous zoom optical system is difficult to meet the requirements of detecting and identifying targets at different distances. The continuous zoom visible light television optical system has a wide coverage range at short focal length and large field of view, and high resolution at long focal length and small field of view. Its large field of view can be used to search for targets over a large range, and its small field of view can be used to identify, track and aim at targets. During the zoom process, the target image can always remain clear, and the field of view can be changed at any angle within the zoom range. In addition, the tracking target will not be lost during the zoom process, and the appropriate working field of view can be selected according to the scene and target characteristics, which greatly improves the human-machine efficiency.

[0004] There are many studies on visible light continuous zoom optical systems in the prior art, such as Chinese patents CN114355589A, CN114355590A, CN114355591A, CN112394500A, CN108873276A, CN106125274A, CN106125272A, CN106094184A, CN106597649A, CN106483644A, CN107238916A, CN107272173A, CN107255861A, etc., which respectively disclose visible light continuous zoom optical systems with different focal length ranges and different magnification ratios. However, these optical systems all adopt a straight-cylindrical optical path with a long length along the optical axis, which is limited in use in spherical airborne optoelectronic systems.

[0005] Chinese patent application number 201610731739.9 discloses a foldable, highly fog-penetrating, high-definition zoom camera lens. The system uses two reflectors to fold the optical path twice to address the shortcoming of the long total optical length of the positive group compensation structure. However, the optical structure length of the system is 367.5 mm, and the volume is still large, making it difficult to achieve miniaturization and lightweight. It has limitations when applied to airborne optoelectronic systems that have strict requirements on volume and weight.

[0006] The Chinese patent application number 201510481734.0 discloses a large-target continuous zoom optical system, which has a target surface of 1 inch and is suitable for high-definition CCD or CMOS cameras with a pixel number of 1920×1080, a pixel size of 7.4μm, and a target surface of 1 inch, and is also suitable for high-definition CCD or CMOS cameras with a pixel number of 1920×1080, a pixel size of 5.5μm, and a target surface of 2 / 3 inches. In addition, the focal length of the optical system is 35mm to 700mm, which greatly improves the long-distance observation capability and can be applied to high-altitude airborne optoelectronic systems. However, the light rays at the reflector 51 and the reflector 52 of the system are all converging rays, and there is a defect that the image quality decreases during the swinging process of the fast reflector when the fast reflector FSM is used. Summary of the invention

[0007] In order to solve the technical problem that the traditional high-definition visible light continuous zoom optical system cannot introduce a fast reflector FSM used for secondary image stabilization in the airborne optoelectronic system, the present invention provides a high-definition visible light television continuous zoom optical system, which can introduce a fast reflector FSM in the optical path to achieve the image stabilization function.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A high-definition visible light television continuous zoom optical system comprises a front fixed group, a magnification group, a compensation group and a rear fixed group which are arranged in sequence along a common optical axis in a light propagation direction; the front fixed group consists of a first meniscus negative lens, a first biconvex positive lens, a first meniscus positive lens and a second biconvex positive lens; the magnification group consists of a first biconcave negative lens, a third biconvex positive lens, a second biconcave negative lens and a third biconcave negative lens; the compensation group consists of a fourth biconvex positive lens, a second meniscus negative lens, a fifth biconvex positive lens and a second meniscus positive lens; the rear fixed group consists of a fourth biconcave negative lens, a third meniscus positive lens, a fourth meniscus positive lens, a fifth biconcave negative lens, a sixth biconvex positive lens, a third meniscus negative lens and a fifth meniscus positive lens; an aperture ST is arranged on the optical path between the compensation group and the rear fixed group; during zooming, the magnification group and the compensation group move along the optical axis, and the front fixed group and the rear fixed group remain in place.

[0010] Furthermore, the outgoing light beam of the third meniscus positive lens is a parallel light beam; a fast reflection mirror FSM and a plane folding reflection mirror II are provided in the rear fixed group, and the fast reflection mirror FSM is arranged between the third meniscus positive lens and the fourth meniscus positive lens; the plane folding reflection mirror II is arranged between the fifth meniscus positive lens and the image plane; the normals of the fast reflection mirror FSM and the plane folding reflection mirror II both form an angle of 45° with the optical axis, so that the optical system has a "U"-shaped structure.

[0011] Furthermore, a near infrared filter is provided between the plane folding reflector II and the image plane.

[0012] Furthermore, when a fast reflection mirror for image shift compensation is not needed in the system, the fast reflection mirror FSM is replaced by a plane folding reflection mirror I.

[0013] Furthermore, the zoom group performs axial movement along the optical axis to change the focal length of the system, and the compensation group is used to compensate for the image defocus caused by the movement of the zoom group. When the system changes from the wide-angle end to the telephoto end, the zoom group moves in a direction close to the aperture ST, and the compensation group moves in a direction away from the aperture ST.

[0014] Furthermore, the center distance between the second biconvex positive lens and the first biconcave negative lens is 5.0 to 89.90 mm, the center distance between the third biconcave negative lens and the fourth biconvex positive lens is 5.0 to 132.31 mm, the center distance between the second meniscus positive lens and the aperture ST is 3.5 to 45.85 mm, and in the process of changing from the wide-angle end to the telephoto end, the stroke of the magnification group is 84.9 mm, and the stroke of the compensation group is 42.35 mm.

[0015] Furthermore, the optical system adopts an axially moving front fixed group to achieve image plane defocus compensation within the temperature range of -40°C to +60°C and system defocus compensation caused by changes in the distance of the observed scene, thereby ensuring that the optical system can clearly image targets at different distances under different temperature conditions.

[0016] Further, the concave surface of the first meniscus positive lens is arranged toward the aperture ST, the concave surface of the second meniscus positive lens is arranged toward the aperture ST, and the convex surface of the fourth meniscus positive lens is arranged toward the reflecting surface of the plane folding reflector II.

[0017] Furthermore, the first meniscus negative lens and the first biconvex positive lens form a first cemented lens I; the first biconcave negative lens, the third biconvex positive lens and the second biconcave negative lens form a second cemented lens II; the second meniscus negative lens and the fifth biconvex positive lens form a third cemented lens III; the fourth biconcave negative lens and the third meniscus positive lens form a fourth cemented lens IV; the fifth biconcave negative lens and the sixth biconvex positive lens form a fifth cemented lens V; the third meniscus negative lens and the fifth meniscus positive lens form a sixth cemented lens VI.

[0018] Furthermore, the technical indicators achieved by the optical system are: working band: 0.4μm~0.9μm; F #: 5.5; focal length: 20.5mm~420mm; field of view: 23.8°×13.5°~1.18°×0.66°; among which, F # The calculation formula is f / D, where f is the focal length of the optical system and D is the diameter of the entrance pupil.

[0019] Beneficial effects:

[0020] 1. The outgoing light beam at the third meniscus positive lens of the optical system of the present invention is a parallel light beam, so a fast reflector for image stabilization can be set there. Since the fast reflector is in a parallel light path, the MTF of the optical system will not decrease during the swing of the fast reflector, thereby effectively improving the stabilization accuracy of the airborne optoelectronic system and not causing a decrease in the imaging quality at the edge field of view of the optical system.

[0021] 2. When the high-definition visible light television continuous zoom optical system is in a static imaging application environment, there is no need to set a fast reflector FSM in the optical path. Instead, an ordinary plane folding reflector is used to replace it to form a U-shaped optical path structure, which effectively shortens the axial length of the system. The volume of the optical path system is less than 258mm (length) × 91.5mm (width) × 127mm (height), realizing the miniaturization of the system.

[0022] 3. The movement trajectory curves of the variable power lens and the compensation lens of the optical system of the present invention are continuous and smooth during the zooming process, without any sudden inflection points, thereby ensuring clear imaging throughout the zooming process without any motion lag. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Light path diagram of the optical system of the present invention when in telephoto 420mm state;

[0024] Figure 2 Light path diagram of the optical system of the present invention when in the mid-focus state of 200mm;

[0025] Figure 3 Light path diagram of the optical system of the present invention when in the short-focus state of 20.5 mm;

[0026] Figure 4 The transfer function diagram of the optical system of the present invention when in the telephoto state of 420mm;

[0027] Figure 5 The transfer function diagram of the optical system of the present invention when in the mid-focus state of 200mm;

[0028] Figure 6 The transfer function diagram of the optical system of the present invention when in the short-focus state of 20.5 mm;

[0029] Figure 7Point diagram of the optical system of the present invention when in telephoto 420mm state;

[0030] Figure 8 The spot diagram of the optical system of the present invention when in the middle focus state of 200mm;

[0031] Fig. 9 The spot diagram of the optical system of the present invention when in the short-focus state of 20.5 mm;

[0032] Fig.10 The motion curve of the optical system of the present invention during the zooming process. DETAILED DESCRIPTION

[0033] In order to make the above features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings, which are only examples and are not drawn strictly to scale.

[0034] In the description of the present invention, it is necessary to understand that if there are terms such as "upper", "lower", "front", "back", "left", "right", etc. to indicate directions or positional relationships, they only correspond to the drawings of the present application and are for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific direction.

[0035] The terms "first", "second" and "third" are used for descriptive purposes only and refer to the order in which lenses of this type appear. They are distinguished in the description and should not be understood as indicating or implying relative importance.

[0036] like Figure 1 to Figure 3 The high-definition visible light television continuous zoom optical system shown in the figure adopts a positive group mechanical compensation continuous zoom design, including a front fixed group, a zoom group, a compensation group, and a rear fixed group; the front fixed group is composed of a first meniscus negative lens 1, a first biconvex positive lens 2, a first meniscus positive lens 3, and a second biconvex positive lens 4; the zoom group is composed of a first biconcave negative lens 5, a third biconvex positive lens 6, a second biconcave negative lens 7, and a third biconcave negative lens 8; the compensation group is composed of a fourth biconvex positive lens 9, a second meniscus negative lens 10, a fifth biconvex positive lens 11, a second meniscus positive lens 12; the rear fixed group is composed of a fourth double concave negative lens 13, a third meniscus positive lens 14, a fourth meniscus positive lens 16, a fifth double concave negative lens 17, a sixth double convex positive lens 18, a third meniscus negative lens 19, and a fifth meniscus positive lens 20; the front fixed group, the zoom group, the compensation group, and the rear fixed group have a total of 19 lenses; the front fixed group, the zoom group, the compensation group, and the rear fixed group are arranged in sequence from left to right along the optical axis (i.e., along the direction of light propagation) and are arranged on the same optical axis; during the zooming process, the zoom group and the compensation group move along the optical axis, and the front fixed group and the rear fixed group remain in place.

[0037] An aperture ST is provided on the optical path between the compensation group and the rear fixed group, and a near infrared filter 22 is provided on the optical path in front of the image plane 23 .

[0038] In the high-definition visible light television continuous zoom optical system of the present invention, the outgoing light beam of the third meniscus positive lens 14 is a parallel light beam.

[0039] A fast reflection mirror FSM15 and a plane folding reflection mirror II21 are arranged in the rear fixed group, and the fast reflection mirror FSM15 is arranged between the third meniscus positive lens 14 and the fourth meniscus positive lens 16; the plane folding reflection mirror II21 is arranged between the fifth meniscus positive lens 20 and the near-infrared filter 22; the normals of the fast reflection mirror FSM15 and the plane folding reflection mirror II21 are set at an angle of 45° with the optical axis; if a fast reflection mirror for image shift compensation is not needed in the system, the fast reflection mirror FSM15 can be replaced by a plane folding reflection mirror I, which is only used to realize the turning of the light path.

[0040] The zoom group moves along the axial direction to change the focal length of the system. When the system changes from the wide-angle end (short focus) to the telephoto end (long focus), the zoom group moves in the direction close to the aperture ST. The compensation group is used to compensate for the image defocus caused by the movement of the zoom group, thereby ensuring clear imaging during the zooming process. When the system changes from the wide-angle end to the telephoto end, the compensation group moves in the direction away from the aperture ST.

[0041] In the optical system, the concave surface of the first meniscus positive lens 3 is arranged toward the aperture ST, the concave surface of the second meniscus positive lens 12 is arranged toward the aperture ST, and the convex surface of the fourth meniscus positive lens 16 is arranged toward the reflecting surface of the plane folding reflector II21.

[0042] The center distance between the second biconvex positive lens 4 and the first biconcave negative lens 5 is 5.0-89.90 mm, the center distance between the third biconcave negative lens 8 and the fourth biconvex positive lens 9 is 5.0-132.31 mm, and the center distance between the second meniscus positive lens 12 and the aperture ST is 3.5-45.85 mm; in the process of changing from the wide-angle end to the telephoto end, the stroke of the magnification group is 84.9 mm, and the stroke of the compensation group is 42.35 mm.

[0043] The optical system of the present invention adopts an axially moving front fixed group to achieve image plane defocus compensation within the temperature range of -40°C to +60°C and system defocus compensation caused by changes in the distance of the observed scene, thereby ensuring clear imaging of objects at different distances, thereby ensuring clear imaging of targets at different distances under different temperature conditions.

[0044] The optical system of the present invention is provided with a plurality of cemented lenses, specifically, the first meniscus negative lens 1 and the first biconvex positive lens 2 form a first cemented lens I; the first biconcave negative lens 5, the third biconvex positive lens 6, and the second biconcave negative lens 7 form a second cemented lens II; the second meniscus negative lens 10 and the fifth biconvex positive lens 11 form a third cemented lens III; the fourth biconcave negative lens 13 and the third meniscus positive lens 14 form a fourth cemented lens IV; the fifth biconcave negative lens 17 and the sixth biconvex positive lens 18 form a fifth cemented lens V; the third meniscus negative lens 19 and the fifth meniscus positive lens 20 form a sixth cemented lens VI.

[0045] The materials of the four lenses in the front fixed group are H-LAF4, H-FK71, H-ZK7 and H-ZLAF68N, the materials of the four lenses in the zoom group are H-FK71, H-ZF52, H-LAK52 and H-ZLAF55D, the materials of the four lenses in the compensation group are H-ZPK2A, H-ZF7LA, H-FK71 and H-ZBAF3, and the materials of the seven lenses in the rear fixed group are H-LAF52, H-ZF4A, H-ZPK2A, H-ZLAF75A, H-LAF1, H-LAF10LA and H-F4.

[0046] Preferably, the first meniscus negative lens 1 satisfies the following conditions: -0.6≤f1 / f≤-0.5, Nd1=1.75, Vd1=34.99, wherein f is the focal length of the optical system in the telephoto state, f1 is the effective focal length of the first meniscus negative lens 1, Nd1 is the refractive index of the d-line of the lens material of the first meniscus negative lens 1, and Vd1 is the d-line Abbe constant of the material of the first meniscus negative lens 1.

[0047] The first biconvex positive lens 2 satisfies the following conditions: 0.4≤f2 / f≤0.6, Nd2=1.456, Vd2=90.27, wherein f is the focal length of the optical system in the telephoto state, f2 is the effective focal length of the first biconvex positive lens 2, Nd2 is the refractive index of the d-line material of the first biconvex positive lens 2, and Vd2 is the d-line Abbe constant of the material of the first biconvex positive lens 2.

[0048] The first meniscus positive lens 3 satisfies the following conditions: 1.5≤f3 / f≤1.7, Nd3=1.613, Vd3=60.58, wherein f is the focal length of the optical system in the telephoto state, f3 is the effective focal length of the first meniscus positive lens 3, Nd3 is the refractive index of the d-line material of the first meniscus positive lens 3, and Vd3 is the d-line Abbe constant of the material of the first meniscus positive lens 3.

[0049] The second biconvex positive lens 4 satisfies the following conditions: 0.4≤f4 / f≤0.6, Nd4=1.883, Vd4=39.22, wherein f is the focal length of the optical system in the telephoto state, f4 is the effective focal length of the second biconvex positive lens 4, Nd4 is the refractive index of the d-line material of the second biconvex positive lens 4, and Vd4 is the d-line Abbe constant of the material of the second biconvex positive lens 4.

[0050] The first biconcave negative lens 5 satisfies the following conditions: -0.2≤f5 / f≤-0.15, Nd5=1.456, Vd5=90.27, wherein f is the focal length of the optical system in the telephoto state, f5 is the effective focal length of the first biconcave negative lens 5, Nd5 is the refractive index of the d-line material of the first biconcave negative lens 5, and Vd5 is the d-line Abbe constant of the material of the first biconcave negative lens 5.

[0051] The third biconvex positive lens 6 satisfies the following conditions: 0.05≤f6 / f≤0.1, Nd6=1.84666, Vd6=23.78, wherein f is the focal length of the optical system in the telephoto state, f6 is the effective focal length of the third biconvex positive lens 6, Nd6 is the refractive index of the d-line material of the third biconvex positive lens 6, and Vd6 is the d-line Abbe constant of the material of the third biconvex positive lens 6.

[0052] The second biconcave negative lens 7 satisfies the following conditions: -0.1≤f7 / f≤-0.05, Nd7=1.729, Vd7=54.68, wherein f is the focal length of the optical system in the telephoto state, f7 is the effective focal length of the second biconcave negative lens 7, Nd7 is the refractive index of the d-line material of the second biconcave negative lens 7, and Vd7 is the d-line Abbe constant of the material of the second biconcave negative lens 7.

[0053] The third biconcave negative lens 8 satisfies the following conditions: -0.2≤f8 / f≤-0.1, Nd8=1.8348, Vd8=42.73, wherein f is the focal length of the optical system in the telephoto state, f8 is the effective focal length of the third biconcave negative lens 8, Nd8 is the refractive index of the d-line material of the third biconcave negative lens 8, and Vd8 is the d-line Abbe constant of the material of the third biconcave negative lens 8.

[0054] The fourth biconvex positive lens 9 satisfies the following conditions: 0.2≤f9 / f≤0.3, Nd9=1.603, Vd9=65.47, wherein f is the focal length of the optical system in the telephoto state, f9 is the effective focal length of the fourth biconvex positive lens 9, Nd9 is the refractive index of the d-line material of the fourth biconvex positive lens 9, and Vd9 is the d-line Abbe constant of the material of the fourth biconvex positive lens 9.

[0055] The second meniscus negative lens 10 satisfies the following condition: -0.25≤f 10 / f≤-0.15,Nd 10=1.8052, Vd 10 =25.46, where f is the focal length of the optical system in telephoto state, f 10 is the effective focal length of the second meniscus negative lens 10, Nd 10 is the refractive index of the material of the second meniscus negative lens 10 at line d, Vd 10 is the d-line Abbe constant of the material of the second meniscus negative lens 10 .

[0056] The fifth biconvex positive lens 11 satisfies the following condition: 0.12≤f 11 / f≤0.16,Nd 11 =1.4565, Vd 11 =90.27, where f is the focal length of the optical system in telephoto state, f 11 is the effective focal length of the fifth biconvex positive lens 11, Nd 11 is the refractive index of the material of the fifth biconvex positive lens 11 at line d, Vd 11 is the d-line Abbe constant of the material of the fifth biconvex positive lens 11.

[0057] The second meniscus positive lens 12 satisfies the following conditions: 0.2≤f 12 / f≤0.3,Nd 12 =1.6569, Vd 12 =51.12, where f is the focal length of the optical system in telephoto state, f 12 is the effective focal length of the second meniscus positive lens 12, Nd 12 is the refractive index of the material d line of the second meniscus positive lens 12, Vd 12 is the d-line Abbe constant of the material of the second meniscus positive lens 12 .

[0058] The fourth biconcave negative lens 13 satisfies the following condition: -0.05≤f 13 / f≤-0.03,Nd 13 =1.7859, Vd 13 =44.19, where f is the focal length of the optical system in telephoto state, f 13 is the effective focal length of the fourth biconcave negative lens 13, Nd 13 is the refractive index of the material of the fourth biconcave negative lens 13 at d line, Vd 13 is the d-line Abbe constant of the material of the fourth biconcave negative lens 13.

[0059] The third meniscus positive lens 14 satisfies the following condition: 0.05≤f 14 / f≤0.1,Nd 14 =1.7282, Vd 14 =28.32, where f is the focal length of the optical system in telephoto state, f 14is the effective focal length of the third meniscus positive lens 14, Nd 14 is the refractive index of the material of the third meniscus positive lens 14 at line d, Vd 14 is the d-line Abbe constant of the material of the third meniscus positive lens 14 .

[0060] The fourth meniscus positive lens 16 satisfies the following condition: 0.1≤f 16 / f≤0.2,Nd 16 =1.603, Vd 16 =65.47, where f is the focal length of the optical system in telephoto state, f 16 is the effective focal length of the fourth meniscus positive lens 16, Nd 16 is the refractive index of the material of the fourth meniscus positive lens 16 at line d, Vd 16 is the d-line Abbe constant of the material of the fourth meniscus positive lens 16 .

[0061] The fifth biconcave negative lens 17 satisfies the following condition: -0.1≤f 17 / f≤-0.05,Nd 17 =1.90366, Vd 17 =31.32, where f is the focal length of the optical system in telephoto state, f 17 is the effective focal length of the fifth biconcave negative lens 17, Nd 17 is the refractive index of the material of the fifth biconcave negative lens 17 at d line, Vd 17 is the d-line Abbe constant of the material of the fifth biconcave negative lens 17.

[0062] The sixth biconvex positive lens 18 satisfies the following condition: 0.05≤f 18 / f≤0.1,Nd 18 =1.6936, Vd 18 =49.19, where f is the focal length of the optical system in telephoto state, f 18 is the effective focal length of the sixth biconvex positive lens 18, Nd 18 is the refractive index of the sixth biconvex positive lens 18 material at d line, Vd 18 is the d-line Abbe constant of the material of the sixth biconvex positive lens 18.

[0063] The third meniscus negative lens 19 satisfies the following condition: -0.15≤f 19 / f≤-0.1,Nd 19 =1.788, Vd 19 =47.49, where f is the focal length of the optical system in telephoto state, f 19 is the effective focal length of the third meniscus negative lens 19, Nd 19 is the refractive index of the material d line of the third meniscus negative lens 19, Vd 19is the d-line Abbe constant of the material of the third meniscus negative lens 19.

[0064] The fifth meniscus positive lens 20 satisfies the following condition: 0.05≤f 20 / f≤0.1,Nd 20 =1.620, Vd 20 =36.35, where f is the focal length of the optical system in telephoto state, f 20 is the effective focal length of the fifth meniscus positive lens 20, Nd 20 is the refractive index of the material of the fifth meniscus positive lens 20 at line d, Vd 20 is the d-line Abbe constant of the material of the fifth meniscus positive lens 20.

[0065] The technical indicators achieved by the optical system of the present invention are shown in Table 1, wherein the calculation formula of F# (optical system F number) is f / D, f is the focal length of the optical system, and D is the incident pupil diameter. Table 1 Technical indicators of the optical system of the present invention parameter Technical indicators Detector resolution 1920×1080 Pixel size 4.5μm Working band 0.4μm~0.9μm <![CDATA[F # (Optical System F Number)]]> 5.5 focal length 20.5mm~420mm Field of view 23.8°×13.5°～1.18°×0.66°

[0066] Table 2 lists the detailed data of the embodiment of the optical system according to the present invention when the focal length is 20.5mm to 420mm, which includes the surface type, radius of curvature, thickness and material of each lens. Among them, the units of the radius of curvature and thickness of the lens are both mm, and the radius of curvature of the spherical surface and the aspherical surface refers to the radius of curvature at the intersection of the lens surface and the optical axis. Among them, the "radius" in Table 2 represents the radius of curvature of the surface, and its positive and negative determination principle is: the intersection of the surface and the main optical axis is taken as the starting point, and the center of the curved surface of the surface is taken as the end point. If the direction of the connecting line is the same as the direction of light propagation, it is positive, otherwise it is negative. If the surface is a plane, the radius of curvature of the surface is infinite; the "thickness" in Table 2 gives the distance between two adjacent surfaces on the optical axis, and its positive and negative determination principle is: take the vertex of the current surface as the starting point, and the vertex of the next surface as the end point. If the direction of the connecting line is the same as the direction of light propagation, it is positive, otherwise it is negative. If the material between the two surfaces is infrared material, the thickness represents the lens thickness, and if there is no material between the two surfaces, it represents the air gap between the two lenses. Table 2 Detailed data of the optical system of the embodiment of the present invention

[0067] After optical design software simulation, such as Figure 4 , Figure 5 , Figure 6 As shown, the transfer functions of the optical system of the present invention in the long focus, medium focus and short focus states are all greater than 0.35 at the characteristic frequency 111lp / mm of the infrared detector; Figure 7 , Figure 8 , Fig. 9 As shown in the figure, they are the spot diagrams in the long focus, medium focus and short focus states respectively. The diffuse spot diameter of the system is equivalent to the size of the detector pixel, indicating that the continuous zoom optical system has excellent imaging performance. Fig.10 As shown, the motion curves of the zoom and compensation groups of the continuous zoom optical system are continuous and smooth during the zooming process, and there is no mutation point, indicating that the system can zoom smoothly without any stuck phenomenon.

[0068] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A high-definition visible light television continuous zoom optical system, comprising a front fixed group, a zoom group, a compensation group and a rear fixed group arranged in sequence along the optical axis in the direction of light propagation; characterized in that: The front fixed group is composed of a first meniscus negative lens (1), a first biconvex positive lens (2), a first meniscus positive lens (3), and a second biconvex positive lens (4); the zoom group is composed of a first biconcave negative lens (5), a third biconvex positive lens (6), a second biconcave negative lens (7), and a third biconcave negative lens (8); the compensation group is composed of a fourth biconvex positive lens (9), a second meniscus negative lens (10), a fifth biconvex positive lens (11), and a second meniscus positive lens (12); the rear fixed group is composed of a fourth biconcave negative lens (13), a third meniscus positive lens (14), a fourth meniscus positive lens (16), a fifth biconcave negative lens (17), a sixth biconvex positive lens (18), a third meniscus negative lens (19), and a fifth meniscus positive lens (20); an aperture ST is provided on the optical path between the compensation group and the rear fixed group; during zooming, the zoom group and the compensation group move along the optical axis, and the front fixed group and the rear fixed group remain in place.

2. The high-definition visible light television continuous zoom optical system according to claim 1, characterized in that: The output light beam of the third meniscus positive lens (14) is a parallel light beam; a fast reflection mirror FSM (15) and a plane folding reflection mirror II (21) are arranged in the rear fixed group; the fast reflection mirror FSM (15) is arranged between the third meniscus positive lens (14) and the fourth meniscus positive lens (16); the plane folding reflection mirror II (21) is arranged between the fifth meniscus positive lens (20) and the image plane (23); the normal lines of the fast reflection mirror FSM (15) and the plane folding reflection mirror II (21) are both at an angle of 45° with the optical axis, so that the optical system has a "U"-shaped structure.

3. The high-definition visible light television continuous zoom optical system according to claim 2, characterized in that: A near-infrared filter (22) is provided between the plane folding reflector II (21) and the image plane (23).

4. The high-definition visible light television continuous zoom optical system according to claim 2, characterized in that: When a fast reflection mirror for image motion compensation is not needed in the system, the fast reflection mirror FSM (15) is replaced by a flat folding reflection mirror I.

5. The high-definition visible light television continuous zoom optical system according to claim 1, characterized in that: The zoom group performs axial movement along the optical axis to change the focal length of the system. The compensation group is used to compensate for the image defocus caused by the movement of the zoom group. When the system changes from the wide-angle end to the telephoto end, the zoom group moves in a direction close to the aperture ST, and the compensation group moves in a direction away from the aperture ST.

6. The high-definition visible light television continuous zoom optical system according to claim 5, characterized in that: The center distance between the second double convex positive lens (4) and the first double concave negative lens (5) is 5.0 to 89.90 mm, the center distance between the third double concave negative lens (8) and the fourth double convex positive lens (9) is 5.0 to 132.31 mm, and the center distance between the second meniscus positive lens (12) and the aperture ST is 3.5 to 45.85 mm. In the process of changing from the wide-angle end to the telephoto end, the stroke of the zoom group is 84.9 mm, and the stroke of the compensation group is 42.35 mm.

7. The high-definition visible light television continuous zoom optical system according to claim 1, characterized in that: The optical system adopts the method of axially moving the front fixed group to realize the image plane defocus compensation of the system within the temperature range of -40°C to +60°C and the system defocus compensation caused by the distance change of the observed scene.

8. The high-definition visible light television continuous zoom optical system according to claim 1, characterized in that: The concave surface of the first meniscus positive lens (3) is arranged toward the aperture ST, the concave surface of the second meniscus positive lens (12) is arranged toward the aperture ST, and the convex surface of the fourth meniscus positive lens (16) is arranged toward the reflecting surface of the plane folding reflector II (21).

9. The high-definition visible light television continuous zoom optical system according to claim 1, characterized in that: The first meniscus negative lens (1) and the first biconvex positive lens (2) form a first cemented lens I; the first biconcave negative lens (5), the third biconvex positive lens (6) and the second biconcave negative lens (7) form a second cemented lens II; the second meniscus negative lens (10) and the fifth biconvex positive lens (11) form a third cemented lens III; the fourth biconcave negative lens (13) and the third meniscus positive lens (14) form a fourth cemented lens IV; the fifth biconcave negative lens (17) and the sixth biconvex positive lens (18) form a fifth cemented lens V; the third meniscus negative lens (19) and the fifth meniscus positive lens (20) form a sixth cemented lens VI.

10. The high-definition visible light television continuous zoom optical system according to claim 1, characterized in that: The technical indicators achieved by the optical system are: working band: 0.4μm~0.9μm; F # : 5.5; focal length: 20.5mm~420mm; field of view: 23.8°×13.5°~1.18°×0.66°; among which, F # The calculation formula is f / D , f is the focal length of the optical system, D is the entrance pupil diameter.

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