A dual-band three-field-of-view switching zoom Offner spectral imaging system

Abstract

The present invention relates to a dual-band, three-field-of-view switchable zoom Offner spectral imaging system, comprising a front switchable zoom group, a slit, a spectral spectrometer system, a folding reflector, a rear relay system, and a two-color refrigerated infrared detector, arranged sequentially along an optical path. The front switchable zoom group comprises a first front telephoto zoom objective lens group, a second front telephoto zoom objective lens group, and a third front telephoto zoom objective lens group, which are driven by a motor to enter or exit the optical path to achieve three-field zoom. The spectral spectrometer system adopts a convex grating-type Offner structure, comprising a first spectrometer reflector, a second spectrometer reflector, and a third spectrometer reflector, which are arranged sequentially from the object side to the image side, with the second spectrometer reflector being a convex grating. The present invention achieves infrared dual-band, large-zoom-ratio, three-field-of-view zoom spectral imaging, and has the advantages of dual bands, high resolution, a large zoom ratio, a wide zoom range, the ability to quickly switch between multiple fields of view to obtain spectral information, and high-quality imaging.

Description

Technical Field

[0001] The present invention relates to the technical field of spectral imaging, and in particular to a dual-band three-field-of-view switching zoom Offner spectral imaging system. Background Art

[0002] The spectral imaging system combines both image and spectrum information, enabling simultaneous acquisition of both image and spectral information for the target being detected, a crucial advantage for target detection and identification. Infrared imaging spectrometers offer unique advantages due to their strong anti-interference capabilities in complex environments such as aerial detection. Medium-wave infrared excels at detecting high-temperature targets, particularly in humid, low-temperature conditions, and can analyze the radiation spectrum of high-temperature objects in detail. Long-wave infrared, on the other hand, focuses on depicting the contours of objects at room temperature, demonstrating powerful reconnaissance capabilities even in environments with stray radiation or heat sources. The combined use of dual infrared bands allows for more precise target detection, providing significant advantages for dual-band infrared detection technology.

[0003] However, most of the infrared imaging spectrometers currently available at home and abroad are single-band, single-field-of-view, and single-function. Dual-band infrared imaging spectrometers are also mostly fixed-focus structures, and mainly adopt a split-beam structure, sharing a telescope objective system with different detectors for reception. They are large in size, high in cost, complex in structure, and limited in use. They cannot achieve rapid target search with a short-focus and large-field-of-view, rapid identification with a long-focus and small-field-of-view, and accurate acquisition of the spatial and spectral information of the target object. Summary of the Invention

[0004] In order to solve the problems that the existing infrared imaging spectrometers have too single application scenarios and complex dual-band structures, and cannot achieve rapid target search with a short focus and large field of view, and rapid identification and accurate acquisition of spatial and spectral information of target objects with a long focus and small field of view, the present invention provides a dual-band three-field-of-view switching zoom Offner spectral imaging system. The system is an integrated common-optical path infrared dual-band large-zoom switching zoom spectral imaging system that combines transmission and catadioptric structures. Its spectral range is 3.7μm~4.8μm and 7.7μm~9.5μm, and realizes three-field-of-view switching zoom: short focus and large field of view of 32mm (21.75°), medium focus and medium field of view of 200mm (3.52°), and long focus and small field of view of 800mm (0.88°).

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A dual-band three-field switching zoom Offner spectral imaging system, characterized by comprising a front switching zoom group, a slit, a spectral splitting system, a folding reflector, a rear relay system and a two-color refrigerated infrared detector arranged in sequence along an optical path, wherein the slit is located at the imaging position of the front switching zoom group;

[0007] The front switching zoom group includes a first front telephoto zoom objective lens group, a second front telephoto zoom objective lens group and a third front telephoto zoom objective lens group which are driven by a motor to cut in or out of the optical path to realize three-field zoom. When the first front telephoto zoom objective lens group cuts into the optical path, the spectral imaging system is a short-focus large-field optical path system; when the second front telephoto zoom objective lens group cuts into the optical path, the spectral imaging system is a medium-focus medium-field optical path system; when the third front telephoto zoom objective lens group cuts into the optical path, the spectral imaging system is a long-focus small-field optical path system; the first front telephoto zoom objective lens group includes a third front telephoto zoom objective lens group which are coaxially arranged in sequence from the object side to the image side. A front telephoto zoom objective lens, a second front telephoto zoom objective lens, a third front telephoto zoom objective lens, and a fourth front telephoto zoom objective lens; the second front telephoto zoom objective lens group includes a fifth front telephoto zoom objective lens, a sixth front telephoto zoom objective lens, a seventh front telephoto zoom objective lens, and an eighth front telephoto zoom objective lens coaxially arranged from the object side to the image side; the third front telephoto zoom objective lens group adopts an RC reflector structure, including a first front telephoto zoom reflector and a second front telephoto zoom reflector coaxially arranged from the object side to the image side, and the first front telephoto zoom reflector and the second front telephoto zoom reflector are both hyperbolic reflectors;

[0008] The spectrum splitting system adopts a convex grating type Offner structure, including a first spectroscopic reflector, a second spectroscopic reflector and a third spectroscopic reflector arranged in sequence from the object side to the image side, and the second spectroscopic reflector is a convex grating;

[0009] The light emitted by the spectral splitting system is refracted by the refracting reflector and then incident on the rear relay system, which includes a first secondary imaging lens, a second secondary imaging lens, a third secondary imaging lens, a fourth secondary imaging lens, a fifth secondary imaging lens and a sixth secondary imaging lens coaxially arranged in sequence from the object side to the image side;

[0010] The light transmitted by the rear relay system is incident on the dual-color refrigerated infrared detector for spectral imaging.

[0011] The dual-band three-field switching zoom Offner spectral imaging system of the present invention combines the advantages of both transmission and catadioptric optical systems, adopts a convex grating-type Offner structure with excellent optical performance as a spectral spectrometer, and realizes infrared dual-band large zoom ratio three-field zoom spectral imaging by switching different front telephoto zoom lens groups driven by a motor. Each subsystem in the present invention is relatively independent in the system design, with high optical transmittance, high resolution, and good imaging quality. The present invention has a high degree of flexibility and can provide spectral imaging including short focus, medium focus, and long focus for a variety of usage scenarios. It can not only quickly obtain target spectrum information within a large field of view with a short focal length, but also obtain detailed spectral information of targets within a small field of view with a long focal length, and has a large zoom range. The present invention has the advantages of dual bands, high resolution, large zoom ratio, large zoom range, and the ability to quickly switch multiple fields of view to obtain spectrum information and high-quality imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the optical path of the spectral imaging system of the present invention during short-focus and large-field imaging;

[0013] Figure 2 Schematic diagram of the optical path during imaging of the mid-focus field of view in the spectral imaging system of the present invention;

[0014] Figure 3 Schematic diagram of the optical path of the spectral imaging system of the present invention during long-focus and small-field imaging;

[0015] Figure 4 This is an MTF curve diagram of the short-focus wavelength (4.25 μm) in the spectral imaging system of the present invention;

[0016] Figure 5 This is the MTF curve of the long-wave (8.5 μm) short-focus spectral imaging system of the present invention;

[0017] Figure 6 is an MTF curve diagram of the mid-focus wavelength (4.25 μm) in the spectral imaging system of the present invention;

[0018] Figure 7 This is the MTF curve of the long-wave (8.5 μm) mid-focus spectral imaging system of the present invention;

[0019] Figure 8 This is an MTF curve diagram of the long focus wavelength (4.25 μm) in the spectral imaging system of the present invention;

[0020] Figure 9 This is the MTF curve of the long-wave (8.5 μm) telephoto spectral imaging system of the present invention.

[0021] Explanation of reference numerals: 1, first front telephoto zoom objective lens group; 11, first front telephoto zoom objective lens; 12, second front telephoto zoom objective lens; 13, third front telephoto zoom objective lens; 14, fourth front telephoto zoom objective lens; 2, second front telephoto zoom objective lens group; 21, fifth front telephoto zoom objective lens; 22, sixth front telephoto zoom objective lens; 23, seventh front telephoto zoom objective lens; 24, eighth front telephoto zoom objective lens; 3, third front telephoto zoom objective lens group; 31, first front telephoto Zoom reflector; 32. Second front telephoto zoom reflector; 4. Slit; 5. Spectral spectrometer system; 51. First spectrometer reflector; 52. Second spectrometer reflector; 53. Third spectrometer reflector; 6. Folding reflector; 7. Rear relay system; 71. First secondary imaging lens; 72. Second secondary imaging lens; 73. Third secondary imaging lens; 74. Fourth secondary imaging lens; 75. Fifth secondary imaging lens; 76. Sixth secondary imaging lens; 8. Two-color cooled infrared detector. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0023] The present invention provides a dual-band three-field switching zoom Offner spectral imaging system, comprising a front switching zoom group, a slit 4, a spectral splitting system 5, a folding reflector 6, a rear relay system 7, and a two-color refrigerated infrared detector 8, which are arranged in sequence along an optical path. The front switching zoom group comprises a first front telephoto zoom objective lens group 1, a second front telephoto zoom objective lens group 2, and a third front telephoto zoom objective lens group 3. The first front telephoto zoom objective lens group 1, the second front telephoto zoom objective lens group 2, and the third front telephoto zoom objective lens group 3 are driven by a motor to rotate and cut into or out of the optical path, thereby achieving three-field zoom.

[0024] like Figure 1 As shown, the first front telephoto zoom objective lens assembly 1 includes a first front telephoto zoom objective lens 11, a second front telephoto zoom objective lens 12, a third front telephoto zoom objective lens 13, and a fourth front telephoto zoom objective lens 14, which are coaxially arranged in sequence from the object side to the image side. The first front telephoto zoom objective lens 11, the second front telephoto zoom objective lens 12, the third front telephoto zoom objective lens 13, and the fourth front telephoto zoom objective lens 14 respectively use a zinc selenide lens, a germanium lens, a zinc sulfide lens, and a zinc selenide lens.

[0025] like Figure 2As shown, the second front telephoto zoom objective lens group 2 includes a fifth front telephoto zoom objective lens 21, a sixth front telephoto zoom objective lens 22, a seventh front telephoto zoom objective lens 23 and an eighth front telephoto zoom objective lens 24 which are coaxial and arranged in sequence from the object side to the image side.

[0026] like Figure 3 As shown, the third front telephoto zoom objective lens group 3 adopts an RC mirror structure, including a first front telephoto zoom reflector 31 (MIRROR) and a second front telephoto zoom reflector 32 (MIRROR) that are coaxial and arranged in sequence from the object side to the image side, and the first front telephoto zoom reflector 31 and the second front telephoto zoom reflector 32 serving as the primary mirror and the secondary mirror respectively are both hyperbolic mirrors.

[0027] The slit 4 is located at the imaging position of the front switching zoom group.

[0028] The spectral spectrometer system 5 employs a convex grating-type Offner structure, comprising a first spectrometer mirror 51 (mirror), a second spectrometer mirror 52 (mirror), and a third spectrometer mirror 53 (mirror), arranged sequentially from the object side to the image side. The second spectrometer mirror 52 is a convex grating, and the line density of the convex grating can be selected to be 0.03 line / μm or other suitable values, which are not limited here. Furthermore, referring to Tables 1 to 3, the curvature radius of the first spectrometer mirror 51 ranges from 95 mm to 110 mm, the curvature radius of the second spectrometer mirror 52 ranges from 40 mm to 55 mm, and the curvature radius of the third spectrometer mirror 53 ranges from 95 mm to 105 mm.

[0029] The traditional infrared imaging spectrometer's spectroscopic element generally adopts a prism or a grating. Because the prism has high transmittance and no spectral overlap, the dispersion is related to the wavelength and is nonlinear, with large spectral line bending and color distortion, so it is suitable for short wavelengths. The plane grating process technology is mature and easy to process, but it only works in a parallel light path and has large spectral line bending. Compared with the above two spectral spectroscopic elements, the convex grating type Offner structure adopted in the present invention is a concentric three-mirror system, in which the second spectroscopic reflector 52 is a convex grating, which has the characteristics of spherical aberration, coma, distortion, astigmatism, field curvature and chromatic aberration and other primary aberrations tending to zero, and has excellent optical performance, thereby further improving the performance of the spectral imaging system.

[0030] To make the system more compact and rational, the spectral imaging system also includes a folding mirror 6 (MIRROR) for deflecting the optical path. Light emitted by the spectral spectrometer 5 is folded by the folding mirror 6 and then incident on a post-relay system 7. To achieve cold stop matching, the spectral imaging system also includes a post-relay system 7, which employs a secondary imaging method to achieve 100% cold stop efficiency. Post-relay system 7 includes a first secondary imaging lens 71, a second secondary imaging lens 72, a third secondary imaging lens 73, a fourth secondary imaging lens 74, a fifth secondary imaging lens 75, and a sixth secondary imaging lens 76, which are coaxially arranged in sequence from the object side to the image side. The first, second, third, fourth, fifth, and sixth secondary imaging lenses 71, 72, 73, 74, 75, and 76 are AMTIR-1, germanium, AMTIR-1, zinc sulfide, zinc selenide, and germanium lenses, respectively.

[0031] The dual-color cooled infrared detector 8 is used to receive light transmitted by the secondary imaging lens group, i.e., the post-relay system 7, and perform spectral imaging. Optionally, the dual-color cooled infrared detector 8 has a size of 320×256, a pixel size of 30μm×30μm, a detector window made of 1mm thick germanium, a filter made of 0.3mm thick germanium, applicable wavelengths: medium wave 3.7μm to 4.8μm, long wave 7.7μm to 9.5μm, a dispersion width of 7.2mm, a spectral resolution of 25nm, and a slit 4 width of 30μm.

[0032] The radial tube length of the spectral imaging system is 335 mm, and the F number of the optical system is 4.

[0033] The front switching zoom group is driven by a motor to rotate and switch to different front telephoto zoom objective lens groups to achieve three-field zoom. Specifically, when the first front telephoto zoom objective lens group 1 cuts into the optical path, the first front telephoto zoom lens group 1, the slit 4, the beam splitter reflector group 5, the folding reflector 6, the rear relay system 7 and the two-color refrigerated infrared detector 8 form a short-focus large-field optical path system. The focal length of the short-focus large-field optical path system is 32mm and the field of view angle is 21.75°; based on the short-focus large-field optical path system, when the motor drives the first front telephoto zoom lens group 1 to rotate and switch to the second front telephoto zoom lens group 2, the second front infrared objective lens group 2, the slit 4, the beam splitter reflector group 5, the folding reflector 6, the rear relay system 7 and the two-color cooled infrared detector 8 form a medium-focus medium-field optical path system, the focal length of the medium-focus medium-field optical path system is 200 mm, and the field of view angle is 3.52°; based on the medium-focus medium-field optical path system, when the motor drives the second front telephoto zoom lens group 2 to continue rotating and switch to the third front telephoto zoom reflector group 3, the third front telephoto zoom reflector group 3, the slit 4, the beam splitting reflector group 5, the folding reflector 6, the rear relay system 7 and the two-color cooled infrared detector 8 form a long-focus small-field optical path system, the focal length of the long-focus small-field optical path system is 800 mm, and the field of view angle is 0.88°.

[0034] Optionally, the first front telephoto zoom objective lens 11 is a zinc selenide lens, the curvature radii of its front and rear surfaces are -35.8 mm and -43.929 mm respectively, and the thickness is 9 mm; the second front telephoto zoom objective lens 12 is a germanium lens, the curvature radius of its front surface is -50.691 mm, the rear surface is an even-order aspheric surface, the vertex curvature radius is -81.701 mm, and the thickness is 8.399 mm; the third front telephoto zoom objective lens 13 is a zinc sulfide lens, the curvature radii of its front and rear surfaces are 39.807 mm and 20.286 mm respectively, and the thickness is 9 mm; the fourth front telephoto zoom objective lens 14 is a zinc selenide lens, the front and rear surfaces are even-order aspheric surfaces, the vertex curvature radii are 16.861 mm and 69.163 mm respectively, and the thickness is 5.438 mm.

[0035] Optionally, the curvature radius of the front and rear surfaces of the fifth front telephoto zoom objective lens 21 are 89.424 mm and 59.326 mm respectively, and the thickness is 11 mm; the curvature radius of the front and rear surfaces of the sixth front telephoto zoom objective lens 22 are 62.609 mm and 116.876 mm respectively, and the thickness is 11 mm; the curvature radius of the front and rear surfaces of the seventh front telephoto zoom objective lens 23 are 220.240 mm and 135.219 mm respectively, and the thickness is 11 mm; the front and rear surfaces of the eighth front telephoto zoom objective lens 24 are even-order aspherical surfaces, with vertex curvature radii of 53.112 mm and 66.350 mm respectively, and a thickness of 7.235 mm.

[0036] Optionally, the curvature radius of the first front telephoto zoom reflector 31 is -432.684 mm, and the curvature radius of the second front telephoto zoom reflector 32 is 155.432 mm.

[0037] Optionally, the first secondary imaging lens 71 is an AMTIR-1 lens, the curvature radii of the front and rear surfaces of which are 38.668 mm and -30.657 mm respectively, and the thickness is 4.003 mm; the second secondary imaging lens 72 is a germanium lens, the curvature radii of the front and rear surfaces of which are -20.478 mm and -44.900 mm respectively, and the thickness is 4 mm; the third secondary imaging lens 73 is an AMTIR-1 lens, the front surface of which is an even aspheric surface, the vertex curvature radius is -13.672, the rear surface curvature radius is -14.532 mm, and the thickness is 5.984mm; the fourth secondary imaging lens 74 is a zinc sulfide lens, the curvature radii of its front and rear surfaces are 5161.251mm and 21.990mm respectively, and the thickness is 4.017mm; the fifth secondary imaging lens 75 is a zinc selenide lens, the curvature radii of its front and rear surfaces are 27.403mm and -26.939mm respectively, and the thickness is 5.626mm; the sixth secondary imaging lens 76 is a germanium lens, the front and rear surfaces are even-order aspheric surfaces, the vertex curvature radii are 13.746mm and 8.220mm respectively, and the thickness is 4.654mm.

[0038] Tables 1 to 3 are the lens parameters of the short-focus large-field-of-view optical system, the medium-focus medium-field-of-view optical system, and the long-focus small-field-of-view optical system, respectively. The units of the parameters are all mm.

[0039] Table 1 Lens parameters of short-focus and large-field-of-view optical system

[0040]

[0041]

[0042] Table 2 Lens parameters of the mid-focus and mid-field optical system

[0043]

[0044]

[0045] Table 3 Lens parameters of telephoto small field of view optical system

[0046]

[0047]

[0048] See also Figures 4 to 9, respectively, are the MTF curves of the spectral imaging system of the present invention during three-field zoom spectral imaging at medium wave (4.25μm) and long wave (8.5μm). It can be seen from the MTF curves that the spectral imaging system is close to the diffraction limit at the characteristic frequency of 17lp / mm, and the imaging quality is good.

[0049] The dual-band three-field switching zoom Offner spectral imaging system of the present invention combines the advantages of both transmission and catadioptric optical systems, adopts a convex grating-type Offner structure with excellent optical performance as a spectral spectrometer, and realizes infrared dual-band 25x large zoom ratio three-field zoom spectral imaging by means of a motor-driven switching method of different front telephoto zoom lens groups. Each subsystem is relatively independent in the system design, with high optical transmittance, high resolution, and good imaging quality. The present invention has a high degree of flexibility and can provide spectral imaging including short focus, medium focus, and long focus for a variety of usage scenarios. It can not only quickly obtain target spectrum information within a large field of view with a short focal length, but also obtain detailed spectral information of targets within a small field of view with a long focal length, and has a large zoom range. The present invention has the advantages of dual bands, high resolution, large zoom ratio, large zoom range, and the ability to quickly switch multiple fields of view to obtain spectrum information and high-quality imaging.

[0050] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0051] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A dual-band three-field switching zoom Offner spectral imaging system, characterized in that: The invention comprises a front switching zoom group, a slit (4), a spectral splitting system (5), a folding reflector (6), a rear relay system (7) and a two-color refrigerated infrared detector (8) which are sequentially arranged along an optical path, wherein the slit (4) is located at an imaging position of the front switching zoom group; The front switching zoom group comprises a first front telephoto zoom objective lens group (1), a second front telephoto zoom objective lens group (2), and a third front telephoto zoom objective lens group (3) which are driven by a motor to cut into or out of the optical path to realize three-field zoom. When the first front telephoto zoom objective lens group (1) cuts into the optical path, the spectral imaging system is a short-focus large-field optical path system; when the second front telephoto zoom objective lens group (2) cuts into the optical path, the spectral imaging system is a medium-focus medium-field optical path system; when the third front telephoto zoom objective lens group (3) cuts into the optical path, the spectral imaging system is a long-focus small-field optical path system. The first front telephoto zoom objective lens group (1) comprises a first telephoto zoom objective lens group (1) and a second telephoto zoom objective lens group (2). The invention comprises a first front telephoto zoom objective lens (11), a second front telephoto zoom objective lens (12), a third front telephoto zoom objective lens (13) and a fourth front telephoto zoom objective lens (14) which are coaxially arranged in sequence from the object side to the image side, wherein the first front telephoto zoom objective lens (11) is a zinc selenide lens, the curvature radii of the front and rear surfaces of which are -35.8 mm and -43.929 mm respectively, and the thickness is 9 mm; the second front telephoto zoom objective lens (12) is a germanium lens, the curvature radius of the front surface of which is -50.691 mm, the rear surface of which is an even-order aspheric surface, the vertex curvature radius of which is -81.701 mm, and the thickness is 8.399 mm; the third front telephoto zoom objective lens (13) is a germanium lens, the curvature radius of the front surface of which is -50.691 mm, the rear surface of which is an even-order aspheric surface, the vertex curvature radius of which is -81.701 mm, and the thickness of which is 8.399 mm; The objective lens (13) is a zinc sulfide lens, the curvature radii of the front and rear surfaces of which are 39.807 mm and 20.286 mm respectively, and the thickness is 9 mm; the fourth front telephoto zoom objective lens (14) is a zinc selenide lens, the front and rear surfaces of which are even-order aspheric surfaces, the vertex curvature radii of which are 16.861 mm and 69.163 mm respectively, and the thickness is 5.438 mm; the second front telephoto zoom objective lens group (2) comprises a fifth front telephoto zoom objective lens (21), a sixth front telephoto zoom objective lens (22), a seventh front telephoto zoom objective lens (23), and an eighth front telephoto zoom objective lens (24) which are coaxially arranged in sequence from the object side to the image side, the fifth front telephoto zoom objective lens (21) and the sixth front telephoto zoom objective lens (22) respectively, and the seventh front telephoto zoom objective lens (23) and the eighth front telephoto zoom objective lens (24) respectively. The front and rear surfaces of the telephoto zoom objective lens (21) have curvature radii of 89.424 mm and 59.326 mm, respectively, and a thickness of 11 mm; the front and rear surfaces of the sixth front telephoto zoom objective lens (22) have curvature radii of 62.609 mm and 116.876 mm, respectively, and a thickness of 11 mm; the front and rear surfaces of the seventh front telephoto zoom objective lens (23) have curvature radii of 220.240 mm and 135.219 mm, respectively, and a thickness of 11 mm; the front and rear surfaces of the eighth front telephoto zoom objective lens (24) are even-order aspherical surfaces, with vertex curvature radii of 53.112 mm and 66.350 mm, respectively, and a thickness of 7.235mm; the third front telephoto zoom objective lens group (3) adopts an RC reflector structure, comprising a first front telephoto zoom reflector (31) and a second front telephoto zoom reflector (32) coaxially arranged from the object side to the image side, and the first front telephoto zoom reflector (31) and the second front telephoto zoom reflector (32) are both hyperbolic reflectors, the curvature radius of the first front telephoto zoom reflector (31) is -432.684mm, and the curvature radius of the second front telephoto zoom reflector (32) is 155.432mm;. The spectral spectrometer system (5) adopts a convex grating type Offner structure, comprising a first spectrometer reflector (51), a second spectrometer reflector (52), and a third spectrometer reflector (53) arranged in sequence from the object side to the image side, and the second spectrometer reflector (52) is a convex grating; The light emitted by the spectral splitting system (5) is incident on the rear relay system (7) after being deflected by the deflecting reflector (6). The rear relay system (7) comprises a first secondary imaging lens (71), a second secondary imaging lens (72), a third secondary imaging lens (73), a fourth secondary imaging lens (74), a fifth secondary imaging lens (75) and a sixth secondary imaging lens (76) which are coaxially arranged in sequence from the object side to the image side; the first secondary imaging lens (71) is an AMTIR-1 lens, the curvature radii of the front and rear surfaces of which are 38.668 mm and -30.657 mm respectively, and the thickness is 4.003 mm; the second secondary imaging lens (72) is a germanium lens, the curvature radii of the front and rear surfaces of which are -20.478 mm and -44.900 mm respectively, and the thickness is 4 mm; The third secondary imaging lens (73) is an AMTIR-1 lens, the front surface of which is an even aspheric surface, the vertex curvature radius is -13.672 mm, the rear surface curvature radius is -14.532 mm, and the thickness is 5.984 mm; the fourth secondary imaging lens (74) is a zinc sulfide lens, the front and rear surfaces of which have curvature radii of 5161.251 mm and 21.990 mm, respectively, and the thickness is 4.017 mm; the fifth secondary imaging lens (75) is a zinc selenide lens, the front and rear surfaces of which have curvature radii of 27.403 mm and -26.939 mm, respectively, and the thickness is 5.626 mm; the sixth secondary imaging lens (76) is a germanium lens, the front and rear surfaces of which are even aspheric surfaces, the vertex curvature radii of 13.746 mm and 8.220 mm, respectively, and the thickness is 4.654 mm; The light transmitted by the rear relay system (7) is incident on the two-color refrigerated infrared detector (8) for spectral imaging.

2. The dual-band three-field switching zoom Offner spectral imaging system according to claim 1, characterized in that: The curvature radius of the first beam splitter reflector (51) ranges from 95 mm to 110 mm, the curvature radius of the second beam splitter reflector (52) ranges from 40 mm to 55 mm, and the curvature radius of the third beam splitter reflector (53) ranges from 95 mm to 105 mm.

3. The dual-band three-field switching zoom Offner spectral imaging system according to claim 2, characterized in that: The line density of the second beam splitting reflector (52) is 0.03 line / μm.

4. The dual-band three-field switching zoom Offner spectral imaging system according to claim 1 or 2, characterized in that: The focal length of the short-focus large-field-of-view optical system is 32 mm, and the field-of-view angle is 21.75°; the focal length of the medium-focus medium-field-of-view optical system is 200 mm, and the field-of-view angle is 3.52°; the focal length of the long-focus small-field-of-view optical system is 800 mm, and the field-of-view angle is 0.88°.

5. The dual-band three-field switching zoom Offner spectral imaging system according to claim 1 or 2, characterized in that: The specification of the dual-color refrigerated infrared detector (8) is 320×256, the pixel size is 30 μm×30 μm, the window is made of germanium material with a thickness of 1 mm, and the filter is made of germanium material with a thickness of 0.3 mm.

6. The dual-band three-field switching zoom Offner spectral imaging system according to claim 1 or 2, characterized in that: The radial tube length of the spectral imaging system is 335 mm.

Images