A high-definition visible light television continuous zoom optical system

Abstract

The present application relates to a kind of high-definition visible light television continuous zoom optical system, including the front fixed group, zoom group, compensation group and rear fixed group in sequence in the direction of light propagation on optical axis;The rear fixed group is provided with fast mirror FSM and plane fold mirror II, the normal of fast mirror FSM, plane fold mirror II is all with optical axis 45 ° angle, so that optical system presents "U" structure, effectively shortens the axial length of system;The outgoing light beam of the third meniscus positive lens of rear fixed group is parallel light beam, so in the swing process of fast mirror, will not cause the transfer function MTF of optical system edge field to drop, to solve the problem of the stability precision deterioration and the decline of imaging system definition due to carrier vibration, while effectively improving the stability precision of airborne optoelectronic system, keep imaging system always clear imaging to target.

Description

Technical Field

[0001] This invention relates to the field of visible light zoom optical systems, and more specifically to a high-definition visible light television continuous zoom optical system. Background Technology

[0002] Visible light cameras are key sensors in airborne optoelectronic equipment, used for wide-area target search, target identification, target tracking, and target guidance during the day. With technological advancements, the requirements for visible light cameras in optoelectronic equipment are increasing. They not only need to provide clear imaging of targets under different fields of view, but also require small size and light weight.

[0003] Single-field-of-view visible light television continuous zoom optical systems struggle to meet the requirements for detecting and identifying targets at varying distances. Continuous zoom visible light television optical systems, however, offer wide coverage at short focal lengths and large fields of view, while maintaining high resolution at long focal lengths and small fields of view. Their large field of view allows for extensive target searching, while the small field of view is used for target identification, tracking, and aiming. The target image remains sharp throughout the zoom process, enabling arbitrary field-of-view transitions within the zoom range. Furthermore, the system does not lose track of the target during zooming and can select an appropriate working field of view based on scene and target characteristics, significantly improving human-machine interface efficiency.

[0004] There is a lot of research on visible light continuous zoom optical systems in the existing technology, such as Chinese patents CN114355589A, CN114355590A, CN114355591A, CN112394500A, CN108873276A, CN106125274A, CN106125272A, CN106094184A, CN106597649A, CN106483644A, CN107238916A, CN107272173A, CN107255861A, etc., which disclose visible light continuous zoom optical systems with different focal length ranges and different zoom ratios. However, these optical systems all use a straight cylindrical optical path, which is relatively long along the optical axis, limiting their use in spherical airborne optoelectronic systems.

[0005] Chinese patent application number 201610731739.9 discloses a folding type high-definition zoom camera lens with strong fog penetration. This system addresses the disadvantage of the long optical total length of the positive group compensation structure by using two mirrors to fold the optical path twice. However, the optical structure of this system is 367.5mm long and still has a large volume, making it difficult to achieve miniaturization and weight reduction. This limits its application in airborne optoelectronic systems where there are strict requirements for size and weight.

[0006] Chinese Patent Application No. 201510481734.0 discloses a large-target-area continuous zoom optical system. This system has a 1-inch target surface and is suitable for high-definition CCD or CMOS cameras with a pixel count of 1920×1080, a pixel size of 7.4μm, and a target surface of 1 inch. It is also suitable for high-definition CCD or CMOS cameras with a pixel count of 1920×1080, a pixel size of 5.5μm, and a target surface of 2 / 3 inch. Furthermore, the system has a focal length of 35mm to 700mm, significantly improving long-distance observation capabilities and making it suitable for airborne optoelectronic systems in high-altitude flight. However, the system uses converging light rays at reflectors 51 and 52, which results in image quality degradation during the swinging of the fast-reflecting mirror (FSM) when used. Summary of the Invention

[0007] To address the technical problem that traditional high-definition visible light continuous zoom optical systems cannot incorporate fast mirrors (FSMs) for secondary image stabilization in airborne optoelectronic systems, this invention provides a high-definition visible light television continuous zoom optical system that can incorporate FSMs in the optical path to achieve image stabilization.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A high-definition visible light television continuous zoom optical system includes a front fixed group, a zoom group, a compensation group, and a rear fixed group arranged sequentially along the optical axis. 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 zoom 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 stop ST is provided in 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, while the front fixed group and the rear fixed group remain in their original positions.

[0010] Furthermore, the output beam of the third meniscus positive lens is a parallel beam; the rear fixed assembly is provided with a fast reflector (FSM) and a planar folding mirror II, the fast reflector (FSM) being positioned between the third and fourth meniscus positive lenses; the planar folding mirror II being positioned between the fifth meniscus positive lens and the image plane; the normals of the fast reflector (FSM) and the planar folding mirror II are both at a 45° angle to the optical axis, making the optical system have a "U" shaped structure.

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

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

[0013] Furthermore, the zoom group moves axially along the optical axis to change the system focal length, and the compensation group is used to compensate for the image plane 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 towards the aperture stop ST, and the compensation group moves away from the aperture stop ST.

[0014] Furthermore, the center-to-center distance between the second biconvex positive lens and the first biconcave negative lens is 5.0–89.90 mm, the center-to-center distance between the third biconcave negative lens and the fourth biconvex positive lens is 5.0–132.31 mm, and the center-to-center distance between the second meniscus positive lens and the aperture stop ST is 3.5–45.85 mm. During the change from the wide-angle end to the telephoto end, the travel of the zoom group is 84.9 mm, and the travel of the compensation group is 42.35 mm.

[0015] Furthermore, the optical system employs an axially moving front-fixed assembly to achieve image plane defocus compensation within a temperature range of -40℃ to +60℃, as well as system defocus compensation caused by changes in the distance of the observed object, thereby ensuring clear imaging of the optical system at different temperature conditions and at different distances.

[0016] Furthermore, the concave surface of the first meniscus positive lens is positioned facing the aperture stop ST, the concave surface of the second meniscus positive lens is positioned facing the aperture stop ST, and the convex surface of the fourth meniscus positive lens is positioned facing the reflecting surface of the planar folding mirror 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; and the third meniscus negative lens and the fifth meniscus positive lens form a sixth cemented lens VI.

[0018] Furthermore, the technical specifications achieved by the optical system are as follows: operating wavelength: 0.4μm~0.9μm; F #F: 5.5; Focal length: 20.5mm~420mm; Field of view: 23.8°×13.5°~1.18°×0.66°; where 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 optical system of the present invention emits a parallel beam at the third meniscus positive lens. Therefore, a fast reflector for image stabilization can be set at this location. Since the fast reflector is in a parallel optical path, the MTF of the optical system will not decrease during the swinging process of the fast reflector, thereby effectively improving the stability accuracy of the airborne optoelectronic system and preventing the image quality at the edge of the optical system from deteriorating.

[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, a regular planar folding reflector is used to replace it, forming a U-shaped optical path structure. This effectively shortens the axial length of the system, and the volume of the optical path system is less than 258mm (length) × 91.5mm (width) × 127mm (height), thus achieving system miniaturization.

[0022] 3. The zoom lens and compensation lens of the optical system of the present invention have a continuous and smooth motion trajectory curve during the zooming process, without any sudden inflection points, thereby ensuring clear imaging throughout the zooming process without any motion lag. Attached Figure Description

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

[0024] Figure 2 Optical path diagram of the optical system of the present invention at a focal length of 200mm;

[0025] Figure 3 The optical path diagram of the optical system of the present invention in the short focal length state of 20.5mm;

[0026] Figure 4 The transfer function diagram of the optical system of the present invention at a focal length of 420mm;

[0027] Figure 5 The transfer function diagram of the optical system of the present invention at a focal length of 200mm;

[0028] Figure 6 The transfer function diagram of the optical system of the present invention at a short focal length of 20.5mm;

[0029] Figure 7A dot plot of the optical system of the present invention at a telephoto focal length of 420mm;

[0030] Figure 8 A dot diagram of the optical system of the present invention at a focal length of 200mm.

[0031] Figure 9 A dot plot of the optical system of the present invention in a short focal length of 20.5mm.

[0032] Figure 10 The motion curve of the optical system of this invention during the zoom process. Detailed Implementation

[0033] To make the above features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings, which are for illustrative purposes only and are not drawn to scale.

[0034] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right" and other terms indicating orientation or positional relationship are only used to correspond to the drawings of this application for the purpose of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation.

[0035] The terms “first,” “second,” and “third” are used for descriptive purposes only, referring to the order in which lenses of this type appear, and are used to distinguish them in the description, and should not be interpreted as indicating or implying relative importance.

[0036] like Figures 1-3 The high-definition visible light television continuous zoom optical system shown employs 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 consists 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 consists 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 consists 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. The system consists of 12 elements; the rear fixed group comprises 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; the front fixed group, zoom group, compensation group, and rear fixed group together have 19 lenses; the front fixed group, zoom group, compensation group, and rear fixed group are arranged sequentially from left to right along the optical axis (i.e., along the direction of light propagation) and are set together along the optical axis; during zooming, the zoom group and compensation group move along the optical axis, while the front fixed group and rear fixed group remain in their original positions.

[0037] An aperture ST is provided in the optical path between the compensation group and the rear fixing group, and a near-infrared filter 22 is provided in 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 output beam of the third meniscus positive lens 14 is a parallel beam.

[0039] The rear fixed assembly includes a fast reflector FSM15 and a planar folding mirror II21. The fast reflector FSM15 is positioned between the third meniscus positive lens 14 and the fourth meniscus positive lens 16. The planar folding mirror II21 is positioned between the fifth meniscus positive lens 20 and the near-infrared filter 22. The normals of the fast reflector FSM15 and the planar folding mirror II21 are set at a 45° angle to the optical axis. If the system does not require a fast reflector for image shift compensation, the planar folding mirror I can be used to replace the fast reflector FSM15, which is only used to achieve optical path deflection.

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

[0041] In the optical system described above, the concave surface of the first meniscus positive lens 3 is positioned toward the aperture stop ST, the concave surface of the second meniscus positive lens 12 is positioned toward the aperture stop ST, and the convex surface of the fourth meniscus positive lens 16 is positioned toward the reflecting surface of the planar folding mirror II21.

[0042] The center-to-center distance between the second biconvex positive lens 4 and the first biconcave negative lens 5 is 5.0–89.90 mm, the center-to-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-to-center distance between the second meniscus positive lens 12 and the aperture ST is 3.5–45.85 mm. During the change from the wide-angle end to the telephoto end, the travel of the zoom group is 84.9 mm, and the travel of the compensation group is 42.35 mm.

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

[0044] The optical system of the present invention includes multiple 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; and 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, where f is the focal length of the optical system in its 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 Abbe constant of the d-line 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, where f is the focal length of the optical system in the long focal state, f2 is the effective focal length of the first biconvex positive lens 2, Nd2 is the refractive index of the d-line of the material of the first biconvex positive lens 2, and Vd2 is the Abbe constant of the d-line 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, where f is the focal length of the optical system in its telephoto state, f3 is the effective focal length of the first meniscus positive lens 3, Nd3 is the refractive index of the d-line of the material of the first meniscus positive lens 3, and Vd3 is the Abbe constant of the d-line 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, where f is the focal length of the optical system in the long focal state, f4 is the effective focal length of the second biconvex positive lens 4, Nd4 is the refractive index of the d-line of the material of the second biconvex positive lens 4, and Vd4 is the Abbe constant of the d-line 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, where f is the focal length of the optical system in its telephoto state, f5 is the effective focal length of the first biconcave negative lens 5, Nd5 is the refractive index of the d-line of the material of the first biconcave negative lens 5, and Vd5 is the Abbe constant of the d-line 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, where f is the focal length of the optical system in its long focal state, f6 is the effective focal length of the third biconvex positive lens 6, Nd6 is the refractive index of the d-line of the material of the third biconvex positive lens 6, and Vd6 is the Abbe constant of the d-line 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, where f is the focal length of the optical system in its telephoto state, f7 is the effective focal length of the second biconcave negative lens 7, Nd7 is the refractive index of the d-line of the material of the second biconcave negative lens 7, and Vd7 is the Abbe constant of the d-line 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, where f is the focal length of the optical system in its telephoto state, f8 is the effective focal length of the third biconcave negative lens 8, Nd8 is the refractive index of the d-line of the material of the third biconcave negative lens 8, and Vd8 is the Abbe constant of the d-line 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, where f is the focal length of the optical system in its long focal length state, f9 is the effective focal length of the fourth biconvex positive lens 9, Nd9 is the refractive index of the d-line of the material of the fourth biconvex positive lens 9, and Vd9 is the Abbe constant of the d-line 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 mode, f 10 The effective focal length of the second meniscus negative lens 10, Nd 10 The refractive index of the d-line of the material of the second meniscus negative lens 10, Vd 10 Let be the Abbe constant for the d-line 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 mode, f 11 The effective focal length of the fifth biconvex positive lens 11, Nd 11 The refractive index of the d-line of the fifth biconvex positive lens 11 material, Vd 11 denoted as Abbe constant for the d-line of the fifth biconvex positive lens 11 material.

[0057] The second meniscus positive lens 12 satisfies the following condition: 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 mode, f 12 The effective focal length of the second meniscus positive lens 12, Nd 12 The refractive index of the d-line of the material of the second meniscus positive lens 12, Vd 12 Let be the Abbe constant for the d-line 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 mode, f 13 The effective focal length of the fourth biconcave negative lens 13, Nd 13 The refractive index of the d-line of the fourth biconcave negative lens 13 material, Vd 13 denoted as Abbe constant for the d-line of the fourth biconcave negative lens 13 material.

[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 mode, f 14The effective focal length of the third meniscus positive lens 14, Nd 14 The refractive index of the d-line of the material of the third meniscus positive lens 14, Vd 14 Let be the Abbe constant for the d-line 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 mode, f 16 The effective focal length of the fourth meniscus positive lens 16, Nd 16 The refractive index of the d-line of the fourth meniscus positive lens 16 material, Vd 16 Let be the Abbe constant for the d-line of the fourth meniscus positive lens 16 material.

[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 mode, f 17 The effective focal length of the fifth biconcave negative lens 17, Nd 17 The refractive index of the d-line of the fifth biconcave negative lens 17 material, Vd 17 denoted as Abbe constant for the d-line of the fifth biconcave negative lens 17 material.

[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 mode, f 18 The effective focal length of the sixth biconvex positive lens 18, Nd 18 The refractive index of the d-line of the sixth biconvex positive lens 18 material, Vd 18 is the Abbe constant for the d-line of the sixth biconvex positive lens 18 material.

[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 mode, f 19 The effective focal length of the third meniscus negative lens 19, Nd 19 The refractive index of the d-line of the material for the third meniscus negative lens 19, Vd 19denoted as Abbe constant for the d-line of the third meniscus negative lens 19 material.

[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 mode, f 20 The effective focal length of the fifth crescent-shaped positive lens 20, Nd 20 The refractive index of the d-line of the fifth crescent-shaped positive lens 20 material, Vd 20 Let be the Abbe constant for the d-line of the fifth crescent-shaped positive lens 20.

[0065] The technical specifications of the optical system of the present invention are shown in Table 1. The formula for calculating F# (F-number of the optical system) is f / D, where f is the focal length of the optical system and D is the diameter of the entrance pupil.

[0066] Table 1 Technical Specifications of the Optical System of the Invention

[0067] parameter Technical indicators Detector resolution 1920×1080 Pixel size 4.5μm Operating 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°

[0068] Table 2 lists detailed data for embodiments of the optical system according to the present invention with focal lengths ranging from 20.5 mm to 420 mm, including the surface shape, radius of curvature, thickness, and material of each lens. The units for the radius of curvature and thickness of the lens are mm. The radius of curvature of spherical and aspherical surfaces refers to the radius of curvature at the intersection of the lens surface and the optical axis. In Table 2, "radius" represents the radius of curvature of the surface, and its sign is determined by taking the intersection of the surface and the principal optical axis as the starting point and the center of the surface as the ending 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 planar, the radius of curvature is infinite. "Thickness" in Table 2 gives the distance between two adjacent surfaces on the optical axis, and its sign is determined by taking the vertex of the current surface as the starting point and the vertex of the next surface as the ending 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; if there is no material between the two surfaces, it represents the air gap between the two lenses.

[0069] Table 2 Detailed data of the optical system in the embodiments of the present invention

[0070]

[0071]

[0072] After simulation using optical design software, such as Figure 4 , Figure 5 , Figure 6As shown, the transfer function of the optical system of the present invention in the long focal length, medium focal length, and short focal length states is greater than 0.35 at the characteristic frequency 111lp / mm of the infrared detector; as Figure 7 , Figure 8 , Figure 9 The figures shown are dot plots for telephoto, medium telephoto, and short telephoto states, respectively. The diameter of the blur spot in this system is comparable to the size of the detector pixel, indicating that the continuous zoom optical system has excellent imaging capabilities. Figure 10 As shown, the motion curves of the zoom and compensation groups in this continuous zoom optical system are continuous and smooth during the zoom process, with no abrupt changes, indicating that the system zooms smoothly and will not experience any jamming.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope 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 coaxially along the light propagation direction; characterized in that, The front fixed group consists 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 consists 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 consists 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 consists 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 stop 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, while the front fixed group and the rear fixed group remain in their original positions.

2. The high-definition visible light television continuous zoom optical system according to claim 1, characterized in that, The emitted beam from the third meniscus positive lens (14) is a parallel beam; the rear fixed assembly is provided with a fast reflector FSM (15) and a planar folding reflector II (21), the fast reflector FSM (15) is located between the third meniscus positive lens (14) and the fourth meniscus positive lens (16); the planar folding reflector II (21) is located between the fifth meniscus positive lens (20) and the image plane (23); the normals of the fast reflector FSM (15) and the planar folding reflector II (21) are both at a 45° angle to the optical axis, making the optical system have 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 planar folding mirror 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 the fast mirror for image shift compensation is not required in the system, the fast mirror FSM (15) is replaced by a planar folding mirror I.

5. A high-definition visible light television continuous zoom optical system according to claim 1, characterized in that, The zoom group moves axially along the optical axis to change the system focal length. The compensation group is used to compensate for the image plane 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 towards the aperture stop ST, and the compensation group moves away from the aperture stop ST.

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

7. A high-definition visible light television continuous zoom optical system according to claim 1, characterized in that, The optical system employs an axially moving, fixed-position assembly to achieve image plane defocus compensation within a temperature range of -40℃ to +60℃, as well as system defocus compensation caused by changes in the distance of the observed object.

8. A 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 set towards the aperture stop ST, the concave surface of the second meniscus positive lens (12) is set towards the aperture stop ST, and the convex surface of the fourth meniscus positive lens (16) is set towards the reflecting surface of the planar folding mirror II (21).

9. A 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 the first cemented lens I; the first biconcave negative lens (5), the third biconvex positive lens (6), and the second biconcave negative lens (7) form the second cemented lens II; the second meniscus negative lens (10) and the fifth biconvex positive lens (11) form the third cemented lens III; the fourth biconcave negative lens (13) and the third meniscus positive lens (14) form the fourth cemented lens IV; the fifth biconcave negative lens (17) and the sixth biconvex positive lens (18) form the fifth cemented lens V; the third meniscus negative lens (19) and the fifth meniscus positive lens (20) form the sixth cemented lens VI.

10. A high-definition visible light television continuous zoom optical system according to claim 1, characterized in that, The optical system achieves the following technical specifications: operating wavelength: 0.4μm~0.9μm; F # : 5.5; Focal length: 20.5mm~420mm; Field of view: 23.8°×13.5°~1.18°×0.66°; where, F # The calculation formula is f / D , f The focal length of the optical system. D The diameter is the entrance pupil.

Images