Gas imaging continuous zoom lens

Abstract

The application discloses a gas imaging continuous zoom lens, comprising: an optical system and a zoom mechanical assembly; the optical system is accommodated in the zoom mechanical assembly, and the zoom mechanical assembly adjusts the air distance in the optical system; the optical system comprises: a front fixed group lens (301) with positive refractive power, a variable magnification group lens (303) with negative refractive power, a first compensation group lens (305) with positive refractive power, a second compensation group lens (307) with positive refractive power, a focusing group lens (309) with positive refractive power and a rear fixed group lens (310) with positive refractive power, which are sequentially arranged from an object image end to an imaging end. In the optical system accommodated in the mechanical assembly, the groups of lenses are arranged in the mode of positive-negative-positive-positive-positive-positive according to the refractive power, three aspheric surfaces are used to correct aberration, so that the lens achieves the effects of high imaging quality, compact structure and short variable magnification compensation stroke.

Description

Technical Field

[0001] This application relates to the field of optomechanical design technology, and in particular to a gas imaging continuous zoom lens. Background Technology

[0002] Gas leaks can easily lead to accidents, causing economic losses, environmental pollution, and personal injury, seriously threatening people's lives and property. How to achieve rapid detection of hazardous gas leaks, precise location of the leak source, and reasonable analysis of the spatial distribution and diffusion trends of leaked gases to prevent major gas leak accidents has become an urgent problem to be solved.

[0003] Gas imaging works by using background absorption gas imaging and infrared radiation absorption technology to quickly detect leaking gas and leak sites. When the thermal imager lens scans the detection area, once it passes near the leak point, due to the higher gas concentration in that area, some of the infrared radiation emitted from the target (pipeline, equipment, etc.) is absorbed after passing through the leaking gas. The thermal radiation energy reaching the focal plane array of the infrared thermal imager is less than that of pipes without gas leaks, resulting in a lower pixel temperature rise compared to pipe sections without gas leaks, thus enabling the detection of pipe leaks.

[0004] Existing thermal imaging lenses have the following problems:

[0005] 1. The overall size is too large, making it difficult to meet the requirements of the detection lens size, such as the "An Infrared Thermal Imager" disclosed in CN201710325330.1;

[0006] 2. When existing infrared lenses are used for gas imaging, they are easily affected by thermal radiation from other thermal radiation objects in the detection environment. At the same time, the temperature and humidity of the detection environment cannot be controlled, resulting in errors between the detection results of the gas imaging system and the actual leak detection results, which affects the detection accuracy. Summary of the Invention

[0007] This application addresses the aforementioned technical problems by providing a gas imaging continuous zoom lens. This lens features a compact and small overall structure, facilitating assembly. It boasts high imaging quality, high spatial resolution, a compact structure, short zoom and compensation stroke, long detection distance, light weight, and resistance to vibration and shock. During zooming, the transmission is smooth, stray light is eliminated, and aspherical and diffractive surface profiles are introduced to fully correct aberrations, bringing the theoretically designed MTF of the optical system close to the diffraction limit. The diffuse spot meets the requirements of the detector, thus improving the accuracy of gas imaging results.

[0008] This application provides a gas imaging continuous zoom lens, including: an optical system and a zoom mechanical assembly; the optical system is housed in the zoom mechanical assembly, and the zoom mechanical assembly adjusts the air distance in the optical system;

[0009] The optical system includes, in sequence from the object end to the imaging end: a front fixed lens group 301 with positive optical power, a zoom lens group 303 with negative optical power, a first compensation lens group 305 with positive optical power, a second compensation lens group 307 with positive optical power, a focusing lens group 309 with positive optical power, and a rear fixed lens group 310 with positive optical power;

[0010] The front fixed lens group 301 is a positive meniscus lens, the zoom lens group 303 is a biconcave negative lens, the first compensation lens group 305 is a biconvex positive lens, the second compensation lens group 307 is a positive meniscus lens, the focusing lens group 309 is a positive meniscus lens, and the rear fixed lens group 310 is a positive meniscus lens.

[0011] Preferably, the material of the front fixed lens group 301 is Ge; the material of the zoom lens group 303 is Si; the material of the first compensation lens group 305 is Ge; the material of the second compensation lens group 307 is Si; the material of the focusing lens group 309 is Ge; and the material of the rear fixed lens group 310 is Ge.

[0012] Preferably, a variable first air gap 302 is provided between the front fixed lens group 301 and the zoom lens group 303; a variable second air gap 304 is provided between the zoom lens group 303 and the first compensation lens group 305; a variable third air gap 306 is provided between the first compensation lens group 305 and the second compensation lens group 307; a variable fourth air gap 308 is provided between the second compensation lens group 307 and the focusing lens group 309; and a variable fifth air gap 311 is provided between the focusing lens group 309 and the rear fixed lens group 310.

[0013] Preferably, the zoom lens group 303 is a biconcave negative lens, and the rear end face of the biconcave negative lens is aspherical.

[0014] Preferably, the first compensation group lens 305 is a biconvex positive lens, and the rear end face of the biconvex positive lens is aspherical.

[0015] Preferably, the second compensation lens group 307 is a positive meniscus lens, and the rear end face of the positive meniscus lens is aspherical.

[0016] Preferably, the aspherical surface satisfies the following formula:

[0017]

[0018] in, Z This refers to the position along the optical axis. r The height in the direction perpendicular to the optical axis; c The radius of curvature; k is the conic coefficient; A, B, C, and D are the aspheric coefficients.

[0019] Preferably, the asphericity of the rear end face 404 of the zoom lens 303 is [value missing]. k =0; A=7.324E-009; B=-4.556E-012; C=1.256E-015; D=0;

[0020] The aspheric coefficient of the rear end face 406 of the first compensation group lens 305 is... k =0; A=2.215E-006; B=2.665E-008; C=-2.223E-010; D=0;

[0021] The aspheric coefficient of the rear end face 408 of the second compensation group lens 307 is... k =0; A=3.112E-005; B=2.554E-007; C=-5.32E-009; D=-2.331E-0011.

[0022] Preferably, the front fixed lens group 301 includes: a front end face 401 and a rear end face 402 of the front fixed lens group, the radius of curvature of the front end face 401 of the front fixed lens group is 96 mm; the radius of curvature of the rear end face 402 of the front fixed lens group is 209.4 mm; the zoom lens group 303 includes: a front end face 403 and a rear end face 404 of the zoom lens group, the radius of curvature of the front end face 403 of the zoom lens group is -143.2 mm; the rear end face 404 of the zoom lens group is aspherical; the first compensation lens group 305 includes: a front end face 405 and a rear end face 406 of the first compensation lens group, the radius of curvature of the front end face 405 of the first compensation lens group is 150.4 mm; the rear end face 406 of the first compensation lens group is aspherical; the first The second compensation group lens 307 includes: a front end surface 407 and a rear end surface 408 of the second compensation group lens. The radius of curvature of the front end surface 407 of the second compensation group lens is 20.5 mm. The rear end surface 408 of the second compensation group lens is aspherical. The focusing group lens 309 includes: a front end surface 409 and a rear end surface 410 of the focusing group lens. The radius of curvature of the front end surface 409 of the focusing group lens is -12.9 mm. The radius of curvature of the rear end surface 410 of the focusing group lens is -21 mm. The rear fixed group lens 310 includes: a front end surface 411 and a rear end surface 412 of the rear fixed group lens. The radius of curvature of the front end surface 411 of the rear fixed group lens is 36.2 mm. The radius of curvature of the rear end surface 412 of the rear fixed group lens is 88.2 mm.

[0023] In the system, the lens end faces from left to right are, in order: front end face 401 and rear end face 402 of the front fixed group lens 301; front end face 403 and rear end face 404 of the zoom group lens 303; front end face 405 and rear end face 406 of the first compensation group lens 305; front end face 407 and rear end face 408 of the second compensation group lens 307; front end face 409 and rear end face 410 of the focusing group lens 309; and front end face 411 and rear end face 412 of the rear fixed group lens 310.

[0024] Preferably, the rear end face of the rear fixed lens group 310 is the rear end face 412 of the rear fixed lens group, and the diffraction coefficients are: first-order diffraction coefficient of 4.023E-004; second-order diffraction coefficient of -6.964E-07; and surface wavelength of 3000nm.

[0025] The beneficial effects that this application can produce include:

[0026] 1) The gas imaging continuous zoom lens provided in this application, in the optical system housed in the mechanical components, allocates each group of lenses in the manner of positive-negative-positive-positive-positive-positive-positive, and uses 3 aspherical surfaces to correct phase difference, so that the lens achieves the effects of high imaging quality, compact structure and short zoom compensation stroke.

[0027] 2) The gas imaging continuous zoom lens provided in this application has each lens material of germanium, silicon, germanium, silicon, germanium and germanium respectively set along the incident direction of light, so as to fully eliminate the system phase difference, correct the image plane drift and obtain excellent imaging quality. It is especially suitable for use in gas imaging systems and is conducive to improving the accuracy of gas leak detection.

[0028] 3) The gas imaging continuous zoom lens provided in this application uses an optical system that reduces the cold reflection coefficient, thereby reducing the specular reflection "ghost image" and cold reflection "black spot" away from the detector image plane.

[0029] 4) The gas imaging continuous zoom lens provided in this application adopts a secondary imaging structure, which can reduce the radial size of the system, improve the overall integration, reduce the size, and facilitate installation while ensuring 100% cold aperture efficiency.

[0030] 5) The gas imaging continuous zoom lens provided in this application, used in the mechanical components for mounting optical systems, utilizes optimized design theory to achieve lightweight design of the main lens barrel, cam barrel, and lens frame, effectively reducing the overall weight of the lens and achieving a compact design. The aspect ratio of the lens frame, lens position, and guide pin depth are optimized. The main lens barrel and lens frame feature an anti-light thread structure design, effectively eliminating some stray light. Attached Figure Description

[0031] Figure 1 A schematic diagram of the optical lens structure of the gas imaging continuous zoom lens provided in this application;

[0032] Figure 2 A schematic diagram of the main cross-sectional structure of the gas imaging continuous zoom lens provided in this application;

[0033] Figure 3 A schematic diagram of the end view structure of the gas imaging continuous zoom lens provided in this application;

[0034] Figure 4 for Figure 3 Schematic diagram of the A-direction structure;

[0035] Figure 5 A three-dimensional structural diagram of the main lens barrel provided for this application;

[0036] Figure 6 This is a schematic diagram of the three-dimensional structure of the variable magnification cylinder provided in this application;

[0037] Figure 7 This is a schematic diagram of the three-dimensional structure of the focusing cylinder provided in this application;

[0038] Figure 8 A three-dimensional structural diagram of the end face of the third frame provided in this application;

[0039] Figure 9 A three-dimensional structural diagram of the other end face of the third frame provided in this application;

[0040] Figure 10 A three-dimensional structural diagram of the fourth frame end face provided in this application;

[0041] Figure 11 A three-dimensional structural diagram of the other end face of the fourth frame provided in this application;

[0042] Figure 12 This is a schematic diagram showing the curve movement of the zoom cam groove, the first compensation cam groove, and the second compensation cam groove during the focusing and zooming motion of the gas imaging continuous zoom lens in this embodiment of the application.

[0043] Figure 13 A schematic diagram of the optical lens structure of the gas imaging continuous zoom lens provided in this application.

[0044] Legend:

[0045] 1. First retaining ring; 2. Main lens barrel; 5. Magnification gear ring; 8. Motor gear; 10. Motor mount; 11. Magnification motor; 12. Cam cylinder; 14. Focusing cylinder; 15. Rear lens cap; 17. Fifth lens frame; 19. Sixth retaining ring; 20. Fifth retaining ring; 21. Fourth lens frame; 22. Fourth retaining ring; 23. Third lens frame; 24. Screw; 25. Third retaining ring; 26. Second lens frame; 27. First lens frame; 28. Second retaining ring; 30. Front lens cap; 37. Focusing gear ring; 39. Focusing motor;

[0046] 211. Variable magnification cam groove; 212. First compensation cam groove; 213. Second compensation cam groove; 214. Variable magnification guide groove; 215. First compensation guide groove; 216. Second compensation guide groove; 217. Focusing guide groove; 141. Focusing curve groove; 231. Weight reduction annular groove; 232. Weight reduction hole;

[0047] 301. Front fixed lens group; 302. First air gap; 303. Magnification lens group; 304. Second air gap; 305. First compensation lens group; 306. Third air gap; 307. Second compensation lens group; 308. Fourth air gap; 309. Focusing lens group; 310. Rear fixed lens group; 311. Fifth air gap;

[0048] 401. Front end face of the front fixed lens group; 402. Rear end face of the front fixed lens group; 403. Front end face of the zoom lens group; 404. Rear end face of the zoom lens group; 405. Front end face of the first compensation lens group; 406. Rear end face of the first compensation lens group; 407. Front end face of the second compensation lens group; 408. Rear end face of the second compensation lens group; 409. Front end face of the focusing lens group; 410. Rear end face of the focusing lens group; 411. Front end face of the rear fixed lens group; 412. Rear end face of the rear fixed lens group. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0050] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0051] Technical means not detailed in this application and not used to solve the technical problems of this application are all set according to common general knowledge in the field, and multiple common general knowledge setting methods can be implemented.

[0052] See Figure 1 The gas imaging continuous zoom lens provided in this application includes: an optical system and a zoom mechanical assembly; the optical system is housed in the zoom mechanical assembly, and the zoom mechanical assembly adjusts the air distance in the optical system;

[0053] The optical system includes, in sequence from the object end to the imaging end: a front fixed lens group 301 with positive optical power, a zoom lens group 303 with negative optical power, a first compensation lens group 305 with positive optical power, a second compensation lens group 307 with positive optical power, a focusing lens group 309 with positive optical power, and a rear fixed lens group 310 with positive optical power;

[0054] The front fixed lens group 301 is a positive meniscus lens, the zoom lens group 303 is a biconcave negative lens, the first compensation lens group 305 is a biconvex positive lens, the second compensation lens group 307 is a positive meniscus lens, the focusing lens group 309 is a positive meniscus lens, and the rear fixed lens group 310 is a positive meniscus lens.

[0055] To suppress stray radiation from sources other than scene radiation in the optical system, a 100% cold stop efficiency is employed. For cooled infrared optical systems, the detector's cold stop should be used as the exit pupil of the optical system to achieve 100% cold stop efficiency. Therefore, this continuous zoom system employs a secondary imaging structure, which can reduce the system's radial size while ensuring 100% cold stop efficiency. To avoid affecting the overall performance of the optical system, the aforementioned optical system effectively combines the characteristics of infrared materials, which have higher absorption and refractive index compared to visible light materials.

[0056] In order to fully eliminate system phase difference, correct image plane drift, and improve the accuracy of gas leak detection, preferably, the material of the front fixed group lens 301 is Ge; the material of the zoom group lens 303 is Si; the material of the first compensation group lens 305 is Ge; the material of the second compensation group lens 307 is Si; the material of the focusing group lens 309 is Ge; and the material of the rear fixed group lens 310 is Ge.

[0057] The lenses used in the optical system are temperature sensitive. Considering the impact of changes in ambient temperature on the system, Si is selected as the main material for the zoom group, while Ge is mainly used for other lenses to correct chromatic aberration.

[0058] Preferably, the zoom lens 303 is a biconcave negative lens, and the rear end face of the biconcave negative lens: the rear end face 404 of the zoom lens is an aspherical surface;

[0059] Preferably, the first compensation group lens 305 is a biconvex positive lens, and the rear end face of the biconvex positive lens: the rear end face 406 of the first compensation group lens is an aspherical surface;

[0060] Preferably, the second compensation group lens 307 is a positive meniscus lens, and the rear end face 408 of the positive meniscus lens is an aspherical surface.

[0061] By setting up lenses 301~310 in the above manner, the cold reflection image is optimized, so that the specular reflection "ghost image" and cold reflection "black spot" are far away from the detector image surface.

[0062] Preferably, the aspherical surfaces of the zoom lens group 303, the first compensation lens group 305, and the second compensation lens group 307 satisfy the following formula:

[0063]

[0064] in, Z This refers to the position along the optical axis. r The height in the direction perpendicular to the optical axis; c The radius of curvature; k is the conic coefficient; A, B, C, and D are the aspheric coefficients.

[0065] By setting an aspherical surface on the rear end face of the aforementioned lens to balance system aberrations, the optical system structure is simplified, the imaging quality is improved, and the detection accuracy of gas imaging results is enhanced.

[0066] Preferably, the front fixed lens group 301 includes: a front end face 401 and a rear end face 402 of the front fixed lens group, the radius of curvature of the front end face 401 of the front fixed lens group is 96 mm; the radius of curvature of the rear end face 402 of the front fixed lens group is 209.4 mm; the zoom lens group 303 includes: a front end face 403 and a rear end face 404 of the zoom lens group, the radius of curvature of the front end face 403 of the zoom lens group is -143.2 mm; the rear end face 404 of the zoom lens group is aspherical; the first compensation lens group 305 includes: a front end face 405 and a rear end face 406 of the first compensation lens group, the radius of curvature of the front end face 405 of the first compensation lens group is 150.4 mm; the rear end face 406 of the first compensation lens group is aspherical; the first The second compensation group lens 307 includes: a front end surface 407 and a rear end surface 408 of the second compensation group lens. The radius of curvature of the front end surface 407 of the second compensation group lens is 20.5 mm. The rear end surface 408 of the second compensation group lens is aspherical. The focusing group lens 309 includes: a front end surface 409 and a rear end surface 410 of the focusing group lens. The radius of curvature of the front end surface 409 of the focusing group lens is -12.9 mm. The radius of curvature of the rear end surface 410 of the focusing group lens is -21 mm. The rear fixed group lens 310 includes: a front end surface 411 and a rear end surface 412 of the rear fixed group lens. The radius of curvature of the front end surface 411 of the rear fixed group lens is 36.2 mm. The radius of curvature of the rear end surface 412 of the rear fixed group lens is 88.2 mm.

[0067] Preferably, a variable first air gap 302 is provided between the front fixed lens group 301 and the zoom lens group 303; a variable second air gap 304 is provided between the zoom lens group 303 and the first compensation lens group 305; a variable third air gap 306 is provided between the first compensation lens group 305 and the second compensation lens group 307; a variable fourth air gap 308 is provided between the second compensation lens group 307 and the focusing lens group 309; and a variable fifth air gap 311 is provided between the focusing lens group 309 and the rear fixed lens group 310.

[0068] Specifically, the parameters for each lens are as follows:

[0069]

[0070] The numbers in the table above are used to number any two opposite surfaces of each lens. The radius of curvature in the table refers to the radius of curvature of each surface, and the air gap refers to the distance between two adjacent surfaces. For example, the air gap corresponding to the front end surface 401 of the front fixed lens group is the distance between the front end surface 401 and the rear end surface 402 of the front fixed lens group, which is the thickness of the front fixed lens group 301.

[0071] Preferably, the aspheric coefficient of the rear end face of the zoom lens 303 is [value missing]. k =0; A=7.324E-009; B=-4.556E-012; C=1.256E-015; D=0; The aspheric coefficient of the rear end face of the first compensation group lens 305 is k =0; A=2.215E-006; B=2.665E-008; C=-2.223E-010; D=0; The aspheric coefficient of the rear end face of the second compensation group lens 307 is k =0; A=3.112E-005; B=2.554E-007; C=-5.32E-009; D=-2.331E-0011.

[0072] In a specific embodiment, the aspherical coefficients and aspherical data of the rear end face 404 of the zoom group lens, the rear end face 406 of the first compensation group lens, and the rear end face 408 of the second compensation group lens are shown in the table below:

[0073] Preferably, the rear end face of the rear fixed lens group 310 is the rear end face 412 of the rear fixed lens group, and the diffraction coefficients are: first-order diffraction coefficient of 4.023E-004; second-order diffraction coefficient of -6.964E-07; and surface wavelength of 3000nm.

[0074] The table below shows the diffraction surface coefficients of the rear end facet 412 of the rear fixed lens group:

[0075] noodle surface wavelength C1 C2 412 3000nm 4.023E-004 -6.964E-07

[0076] Where C1: first-order diffraction coefficient; C2: second-order diffraction coefficient;

[0077] The optical system assembled according to the above parameters achieves the following optical performance:

[0078] (1) Focal length: f=30~75mm, zoom ratio up to 2.5 times;

[0079] (2) Field of view range: 19.2°×15.3°~8.3°×5.23°;

[0080] (3) Relative aperture: 1.2;

[0081] (4) Detector adapter: Adapted to a target surface of 320*256 and a pixel size of 30 μm Cooled mid-wave infrared detector;

[0082] (5) Operating temperature: -30℃~+60℃;

[0083] (6) Applicable spectral range: 3 μm ~3.6 μm.

[0084] See Figures 2-11 The specific zoom mechanical components used include: the main lens barrel includes: a front fixed group, a zoom group, a first compensation group, a second compensation group, a focusing group, and a rear fixed group.

[0085] The front fixing group includes: a first pressure ring 1, and the front fixing group lens 301 is installed on the front end of the main lens barrel 2 and the front fixing group lens 301 is fixed and pressed by the first pressure ring 1.

[0086] The zoom lens assembly includes a first frame 27 and a second retaining ring 28. The zoom lens 303 is mounted in the first frame 27 and secured and pressed in place by the second retaining ring 28.

[0087] The first compensation assembly includes a second frame 26 and a third retaining ring 25. The first compensation lens 305 is installed in the second frame 26 and fixed and pressed in place by the third retaining ring 25.

[0088] The second compensation assembly includes a third frame 23 and a fourth pressure ring 22. The second compensation lens 307 is installed in the third frame 23 and fixed and pressed in place by the fourth pressure ring 22.

[0089] The focusing assembly includes a fourth lens frame 21 and a fifth retaining ring 20. The focusing assembly lens 309 is installed in the fourth lens frame 21 and fixed and pressed in place by the fifth retaining ring 20.

[0090] The rear fixation assembly includes a fifth frame 17 and a sixth retaining ring 19. The lens 310 of the rear fixation assembly is installed in the fifth frame 17 and fixed and pressed in place by the sixth retaining ring 19.

[0091] The zoom assembly, first compensation assembly, second compensation assembly, focusing assembly, and rear fixing assembly are sequentially installed into the main lens barrel 2 from the image end to the viewfinder end.

[0092] The outer wall of the main lens barrel 2 is provided with a zoom guide groove 214, a first compensation guide groove 215, a second compensation guide groove 216, and a focusing guide groove 217. A cam cylinder 12 is fitted over the main lens barrel 2. The outer surface of the cam cylinder 12 is provided with a zoom cam groove 211, a first compensation cam groove 212, and a second compensation cam groove 213. The zoom guide groove 214 is aligned with the zoom cam groove 211; the first compensation guide groove 215 is aligned with the first compensation cam groove 212; and the second compensation guide groove 216 is aligned with the second compensation cam groove 213. Multiple bearing assemblies are provided outside the cam cylinder 12. Screws 24 can nest the bearings. Each bearing assembly extends sequentially from the zoom cam groove 211, the first compensation cam groove 212, and the second compensation cam groove 213 into the zoom guide groove 214, the first compensation guide groove 215, and the second compensation cam groove 216, respectively, and is connected to the zoom assembly, the first compensation assembly, and the second compensation assembly.

[0093] The motor mount 10 is located on the outer wall of the main lens barrel 2; the motor mount 10 is equipped with a zoom motor 11, and the motor gear 8 is driven and connected to the zoom motor 11. The motor gear 8 is sleeved on the cam cylinder 12; when the rotor of the zoom motor 11 rotates, it drives the cam cylinder 12 to rotate through the motor gear 8 and the zoom gear ring 5. The cam cylinder 12 transmits the motion to the first lens frame 27, the second lens frame 26 and the third lens frame 23 through the bearing assembly. Under the limiting action of the guide straight groove, the first lens frame 27, the second lens frame 26 and the third lens frame 23 convert the rotational motion of the cam cylinder 12 into the parallel movement of the first lens frame 27, the second lens frame 26 and the third lens frame 23 along the optical axis, thereby realizing the zoom motion.

[0094] In one specific embodiment, a weight-reducing annular groove 231 is provided on one end face of the third frame 23, and a plurality of weight-reducing holes 232 are provided on the other end face. The inner diameter of the weight-reducing holes 232 is 5~6mm and 10~12 holes are arranged around the central axis. The angle formed by the line connecting the center of any two adjacent weight-reducing holes 232 and the center of the third frame 23 is 30~36°, thereby achieving the weight reduction of the frame while ensuring the strength of the frame.

[0095] It also includes: a focusing tube 14; the focusing tube 14 is rotatably mounted at the eyepiece end of the main lens tube 2; a focusing guide groove 217 is provided on the eyepiece end of the main lens tube 2; and a focusing curve groove 141 is provided on the focusing tube 14. The bearing assembly is inserted into the focusing guide groove 217 from the focusing curve groove 141.

[0096] In this embodiment, a focusing motor 39 is mounted on the motor mount 10. The focusing motor 39 is driven to connect with the focusing gear ring 37 on the focusing cylinder 14; the motor gear 8 is connected to the focusing cylinder 14. When the focusing motor 39 drives the focusing cylinder 14 to rotate, the focusing cylinder transmits the motion to the fourth lens frame 21 through the bearing assembly. Under the limiting action of the guide groove, the fourth lens frame 21 converts the rotational motion of the focusing cylinder 14 into the parallel movement of the fourth lens frame 21 along the optical axis, thereby realizing the focusing of the lens.

[0097] In one specific embodiment, a weight-reducing annular groove 231 and a plurality of weight-reducing holes 232 are provided on one end face of the fourth frame 21. The inner diameter of the weight-reducing holes 232 is 5~6mm. 15~20 weight-reducing holes 232 are equidistantly arranged around the central axis of the fourth frame 21. The angle between the center of any two adjacent weight-reducing holes 232 and the center of the fourth frame 21 is 18~24°, thereby achieving the weight reduction of the frame while ensuring the strength of the frame.

[0098] In this embodiment, the zoom motor 11 automatically stops at the long focal length and short focal length endpoints by triggering the limit switch contact on the upper limit block fixed to the cam cylinder 12. The focusing motor 39 automatically stops at the front and rear focusing endpoints by touching the miniature limit switch contact on the limit post set on the focusing cylinder 14.

[0099] In one specific embodiment, a front lens cap 30 is provided on the image end of the main lens tube 2; and a rear lens cap 15 is provided on the image end of the focusing tube 14.

[0100] Using the long-wave infrared continuous zoom lens as described above, when in use, light sequentially passes through the front fixed group lens 301, the zoom group lens 303, the first compensation group lens 305, the second compensation group lens 307, the focusing group lens 309, and the rear fixed group lens 310 to form an image.

[0101] The zoom motor 11 drives the cam cylinder 12 to rotate, and the bearing assembly drives the first lens frame 27, the second lens frame 26 and the third lens frame 23 to move back and forth along the lens barrel axis, thereby causing the zoom lens group 303, the first compensation lens group 305 and the second compensation lens group 307 to move back and forth, adjust the air gap and realize zoom; the focusing motor 39 drives the focusing cylinder 14 to rotate, and the bearing assembly drives the fifth lens frame 17 to move back and forth to focus; the combination of zoom and focusing realizes the electric zoom of the lens.

[0102] The aspect ratio of the first frame 27, the second frame 26, the third frame 23 and the fourth frame 21 was finally determined to be 2:1, the lens position was located at the center of the frame, the guide pin depth was 0.5mm, the offset between each frame was within 0.1mm, and the deflection was within 0.05°.

[0103] Figure 12 This diagram illustrates the movement of the zoom lens cam structure curve in the above-described specific embodiment. The horizontal axis represents the number of optical design points, totaling 793 points; the vertical axis represents the movement of the groove line, where curve 1 corresponds to the movement of the groove line of the zoom cam groove 211; curve 2 corresponds to the movement of the groove line of the first compensation cam groove 212; and curve 3 corresponds to the movement of the groove line of the second compensation cam groove 213. As can be seen from this diagram, the lens provided in this application can perform zoom and focus movements to achieve imaging.

[0104] Using the aforementioned lens and related modules for gas imaging, it is possible to image more than 50 types of hazardous gases. The lens provided in this application supports a wider range of hazardous gases than other lenses on the market. This lens is not only compatible with handheld devices, facilitating quick inspection and repair by personnel to prevent danger and loss, but it can also be installed in online gas monitoring systems for real-time monitoring and digital control and detection.

[0105] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A gas imaging continuous zoom lens, characterized in that, include: Optical system and zoom mechanism components; Optical Department The system is housed within the zoom mechanism, which adjusts the air distance in the optical system. The optical system consists of, in sequence from the object end to the imaging end: a front fixed lens group with positive optical power, a zoom lens group with negative optical power, a first compensation lens group with positive optical power, a second compensation lens group with positive optical power, a focusing lens group with positive optical power, and a rear fixed lens group with positive optical power. The front fixed lens group is a positive meniscus lens; The zoom lens group is a biconcave negative lens, and the rear end face of the biconcave negative lens is aspherical. The first compensation group of lenses is a biconvex positive lens, and the rear end face of the biconvex positive lens is an aspherical surface; The second compensation group lens is a positive meniscus lens, and the rear end face of the positive meniscus lens is aspherical. The focusing lens is a positive meniscus lens; The rear fixed lens group is a positive meniscus lens; Aspherical surfaces satisfy the following equation: in, Z This refers to the position along the optical axis. r The height in the direction perpendicular to the optical axis; c The radius of curvature; k is the conic coefficient; A, B, C, and D are the aspheric coefficients.

2. The gas imaging continuous zoom lens according to claim 1, characterized in that, The material of the front fixed lens group is Ge; the material of the zoom lens group is Si; the material of the first compensation lens group is Ge; the material of the second compensation lens group is Si; the material of the focusing lens group is Ge; and the material of the rear fixed lens group is Ge.

3. The gas imaging continuous zoom lens according to claim 1, characterized in that, A variable first air gap is provided between the front fixed group lens and the zoom group lens; a variable second air gap is provided between the zoom group lens and the first compensation group lens; a variable third air gap is provided between the first compensation group lens and the second compensation group lens; a variable fourth air gap is provided between the second compensation group lens and the focusing group lens; and a variable fifth air gap is provided between the focusing group lens and the rear fixed group lens.

4. The gas imaging continuous zoom lens according to claim 1, characterized in that, The rear end face of the zoom lens: The aspheric coefficient of the rear end face (404) of the zoom lens is k =0; A=7.324E-009; B=-4.556E-012; C=1.256E-015; D=0; The rear end face of the first compensation group lens: The aspheric coefficient of the rear end face (406) of the first compensation group lens is... k =0; A=2.215E-006; B=2.665E-008; C=-2.223E-010; D=0; The rear end face of the second compensation group lens: The aspheric coefficient of the rear end face (408) of the second compensation group lens is k =0; A=3.112E-005; B=2.554E-007; C=-5.32E-009; D=-2.331E-0011.

5. The gas imaging continuous zoom lens according to claim 1, characterized in that, The anterior fixed lens group includes: an anterior end face (401) and an posterior end face (402) of the anterior fixed lens group, wherein the radius of curvature of the anterior end face (401) of the anterior fixed lens group is 96 mm; and the radius of curvature of the posterior end face (402) of the anterior fixed lens group is 209.4 mm. The variable magnification lens includes: a front surface (403) and a rear surface (404) of the variable magnification lens. The radius of curvature of the front surface (403) of the variable magnification lens is -143.2mm; the rear surface (404) of the variable magnification lens is aspherical. The first compensation group lens includes: a front end face (405) and a rear end face (406) of the first compensation group lens. The radius of curvature of the front end face (405) of the first compensation group lens is 150.4 mm. The rear end face (406) of the first compensation group lens is aspherical. The second compensation group lens includes: the front end face (407) of the second compensation group lens and the rear end face (408) of the second compensation group lens. The radius of curvature of the front end face (407) of the second compensation group lens is 20.5 mm; the rear end face (408) of the second compensation group lens is aspherical. The focusing lens group includes: a front surface (409) and a rear surface (410) of the focusing lens group. The radius of curvature of the front surface (409) of the focusing lens group is -12.9mm; the radius of curvature of the rear surface (410) of the focusing lens group is -21mm. The rear fixation lens includes: a front end face (411) and a rear end face (412) of the rear fixation lens. The radius of curvature of the front end face (411) of the rear fixation lens is 36.2 mm; the radius of curvature of the rear end face (412) of the rear fixation lens is 88.2 mm.

6. The gas imaging continuous zoom lens according to claim 1, characterized in that, The rear end face of the rear fixed lens group is the rear end face of the rear fixed lens group (412), and the diffraction coefficients are: first-order diffraction coefficient is 4.023E-004; second-order diffraction coefficient is -6.964E-07; and the surface wavelength is 3000nm.

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