Picture type hyperspectral full-band imaging system based on image space scanning

Abstract

The invention discloses a picture type hyperspectral full-wave band imaging system based on image space scanning. The system comprises a telescope system, an image space scanning mirror, a view field separation device, a spectrograph and a detector, wherein the spectrograph and the detector are arranged at different wave bands from visible light to long-wave infrared light; wherein the image space scanning mirror is in the shape of a cylinder with a right triangle section, a central optical axis is arranged in the image space scanning mirror, and the image space scanning mirror can move in parallel or rotate horizontally along the central optical axis to form rectangular view fields in different directions and at different angles; light from the rectangular area of the earth surface is converged to the image space scanning mirror through the telescope system, and a plurality of rectangular view fields are formed at different positions; and after passing through the field of view separation device, the light is split by a spectrograph and received by a detector in different bands of visible light-long wave infrared, and the problem of virtual focus of an image plane is avoided in the process of obtaining the hyperspectral full-band earth surface information in a picture manner. According to the invention, a foundation is laid for high-resolution area array staring imaging and full-band picture type hyperspectral and multispectral comprehensive detection.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of remote sensing imaging, and particularly relates to a frame type hyperspectral full waveband imaging system based on image scanning. BACKGROUND

[0002] With the rapid development of remote sensing technology, the hyperspectral imaging technology plays an increasingly important role in the fields of geological exploration, environmental monitoring, agricultural assessment and the like due to its ability to simultaneously obtain spatial and spectral information of a target. Although the traditional line field dispersion spectrometric hyperspectral imaging technology can obtain high-purity spectral information, the spectral information of a linear strip is obtained each time, and two-dimensional surface spectral information needs to be formed by splicing multiple continuous strips through forward flight of a platform such as an airplane or a satellite or through scanning by a pre-positioned object scanning mirror of a telescope. However, with the increasing requirements for spatial resolution and spectral resolution, these traditional methods face severe challenges. In particular, for a large-aperture optical system, the volume and weight of the object scanning mirror limit its application, and the high-precision image shift compensation depending on a satellite platform puts forward extremely high requirements on platform control, which becomes a main bottleneck restricting the development of hyperspectral remote sensing technology. For a stationary orbit remote sensing satellite, in order to achieve a meter-level spatial resolution, the aperture of the optical system often needs to reach nearly ten meters, and this problem is particularly prominent.

[0003] In recent years, although domestic and foreign scholars have made certain progress in mirror splicing and lightweight design, there is still a lack of effective solutions to key problems such as efficient image shift compensation, stray light suppression and multi-mode integrated detection of a large-aperture system. In particular, in the application scenario of a super large-aperture (10-meter-level) optical system, the existing technology cannot meet the multiple requirements of spectral-spatial high resolution, wide field of view, high sensitivity and the like, and innovative technical breakthroughs are urgently needed. SUMMARY

[0004] To solve the above technical problems, the application provides a frame type hyperspectral full waveband imaging system based on image scanning, which can be applied to high-resolution multispectral and hyperspectral earth remote sensing imaging, adopts an image scanning method, realizes frame type hyperspectral full waveband imaging, effectively breaks through the limitations of resource requirements and precision control of an existing satellite platform, and solves the bottleneck problem of transition dependence on a satellite platform required for large image shift compensation of stationary orbit frame type hyperspectral data acquisition and medium-low orbit high-resolution detection.

[0005] To achieve the above purpose, the application adopts the following technical scheme:

[0006] A frame type hyperspectral full-band imaging system based on image scanning, the system comprising a telescope system, an image scanning mirror, a field of view separation device, a spectrometer of different bands of visible light to long wave infrared, and a detector of corresponding bands; wherein the image scanning mirror is in the shape of a right triangle section cylinder with a central optical axis, and the image scanning mirror can move parallel to the central optical axis or rotate horizontally to form rectangular fields of view of different directions and angles.

[0007] Light from a rectangular area on the ground is converged to the image scanning mirror through the telescope system, forms multiple rectangular fields of view at different positions, and is then imaged by the spectrometer of different bands of visible light to long wave infrared through the field of view separation device, and finally is received by the detector of corresponding bands.

[0008] The telescope system adopts intermediate primary imaging and a three-time insertion mirror central hole design, and comprises a focal plane compensation mirror, which cooperates with the image scanning mirror to compensate for the difference in image plane position, so as to realize frame type hyperspectral full-band imaging.

[0009] The present application has the following advantages:

[0010] The system forms rectangular fields of view of different directions and angles by moving the image scanning mirror parallel to the central optical axis or rotating it horizontally, realizes multi-mode integrated detection, and greatly improves the data acquisition efficiency. In the high-resolution staring imaging mode, a high-resolution panchromatic image (10m spatial resolution) in a range of 400km*400km can be obtained; in the frame type hyperspectral imaging mode, the hyperspectral data of visible light-short wave infrared and medium wave-long wave infrared bands are collected in turn through the uniform motion of the image scanning mirror, and the spectral resolution can be up to 5nm. The 180° rotation function of the image scanning mirror also supports reverse scanning imaging of the medium-long wave infrared band, without the need for additional mechanical structure adjustment, which significantly enhances the adaptability and flexibility of the system.

[0011] In terms of optical system design, the compact structure of intermediate primary imaging and three-time insertion mirror central hole is adopted, combined with a field of view external stray light diaphragm and a stray light elimination diaphragm, which effectively suppresses stray light interference and significantly improves the signal-to-noise ratio of the system. This design not only optimizes the optical efficiency, but also greatly shortens the total length of the optical system, providing convenience for the engineering realization of large aperture telescopes. At the same time, the application of ultra-thin dichroic filters (thickness not more than 0.1mm) further improves the lightness and integration of the system.

[0012] By the cooperative movement of the image-side scanning mirror and the focal plane compensation mirror, the field of view scanning and the focal plane compensation are directly completed in the image side, the dependence on the high-precision image movement compensation of the satellite platform is broken, and the high-resolution remote sensing task of the large-aperture optical system is particularly suitable. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is a structure schematic diagram of a frame type hyperspectral full waveband imaging system based on image-side scanning according to the present application;

[0014] Figure 2 It is a structure schematic diagram of a telescope focal plane front sub-field layout of a spectrometer of a frame type hyperspectral full waveband imaging system based on image-side scanning according to the present application;

[0015] Figure 3 It is a structure schematic diagram of a telescope focal plane front sub-field layout of a spectrometer of a frame type hyperspectral full waveband imaging system based on image-side scanning according to the present application;

[0016] Figure 4 It is a structure schematic diagram of a frame type hyperspectral full waveband imaging system based on image-side scanning according to the present application;

[0017] Figure 5 It is a structure schematic diagram of a frame type hyperspectral full waveband imaging system based on image-side scanning according to the present application;

[0018] Figure 6 It is an imaging process diagram of a frame type hyperspectral full waveband imaging system based on image-side scanning according to the present application;

[0019] Figure 7 It is a high-resolution panchromatic channel 0.3183°~ -0.3183° field of view MTF evaluation diagram of a frame type hyperspectral full waveband imaging system based on image-side scanning according to the present application;

[0020] Figure 8 It is a visible near-infrared hyperspectral channel field of view from 0.3183° to -0.3183° front and rear image quality contrast MTF evaluation diagram of a frame type hyperspectral full waveband imaging system based on image-side scanning according to the present application, wherein (a) is a 0.3183° MTF evaluation diagram, and (b) is a -0.3183° MTF evaluation diagram;

[0021] Figure 9For the invention, the short-wave infrared hyperspectral channel field of view of the frame type hyperspectral full waveband imaging system based on image scanning is scanned from 0.3183° to -0.3183°, and the front and rear image quality contrast MTF evaluation diagram is as follows, wherein (a) is the 0.3183° MTF evaluation diagram, and (b) is the -0.3183° MTF evaluation diagram.

[0022] Figure 10 For the invention, the middle-wave infrared hyperspectral channel field of view of the frame type hyperspectral full waveband imaging system based on image scanning is scanned from 0.3183° to -0.3183°, and the front and rear image quality contrast MTF evaluation diagram is as follows, wherein (a) is the 0.3183° MTF evaluation diagram, and (b) is the -0.3183° MTF evaluation diagram.

[0023] Figure 11 For the invention, the long-wave infrared hyperspectral channel field of view of the frame type hyperspectral full waveband imaging system based on image scanning is scanned from 0.3183° to -0.3183°, and the front and rear image quality contrast MTF evaluation diagram is as follows, wherein (a) is the 0.3183° MTF evaluation diagram, and (b) is the -0.3183° MTF evaluation diagram.

[0024] Figures:

[0025] Central optical axis 0, telescope system 1, image scanning mirror 2, position adjustment turning mirror 7;

[0026] Primary mirror 1-1, secondary mirror 1-2, field of view external stray light diaphragm 1-3, three-mirror 1-4, focal plane compensation mirror 1-5, stray light elimination diaphragm 1-6;

[0027] Visible light-short-wave infrared field of view separation device 3-1 and middle-wave-long-wave infrared field of view separation device 3-2;

[0028] Visible light-short-wave infrared long-slit diaphragm 3-1-1, visible light-short-wave dichroic filter 3-1-2, middle-wave-long-wave infrared long-slit diaphragm 3-2-1, middle-wave-long-wave dichroic filter 3-2-2;

[0029] Visible light-short-wave infrared double long-slit diaphragm 3-1-3, visible light-short-wave dichroic filter 3-1-4, middle-wave-long-wave infrared double long-slit diaphragm 3-2-3, middle-wave-long-wave dichroic filter 3-2-4;

[0030] Visible long-slit diaphragm 3-1-5, short-wave infrared turning mirror 3-1-6, short-wave infrared long-slit diaphragm 3-1-7, middle-wave long-slit diaphragm 3-2-5, long-wave infrared turning mirror 3-2-6, long-wave infrared long-slit diaphragm 3-2-7;

[0031] Visible near-infrared spectrometer 4-1, short-wave infrared spectrometer 4-2, middle-wave infrared spectrometer 4-3, long-wave infrared spectrometer 4-4;

[0032] The near-infrared detector 5-1, the short-wave infrared detector 5-2, the medium-wave infrared detector 5-3, the long-wave infrared detector 5-4, and the high-resolution area array staring panchromatic detector 5-5 can be seen.

[0033] The first direction field of view 6-1, the second direction field of view 6-2, and the third direction field of view 6-3.

[0034] The first mirror 8-1, the grating 8-2, the second mirror 8-3, the correction lens 8-4, and the spectrometer folding mirror 8-5. DETAILED DESCRIPTION

[0035] The application will be further described below in combination with the drawings and examples.

[0036] The picture frame type hyperspectral full-waveband imaging system based on image scanning according to the application designs a set of hyperspectral imaging load instruments, which can effectively break through the limitations of resource requirements and precision control of the existing satellite platform and realize picture frame type hyperspectral full-waveband imaging.

[0037] Reference Figure 1 The picture frame type hyperspectral full-waveband imaging system based on image scanning according to the application is a structural schematic diagram, which comprises a telescope system 1, an image scanning mirror 2, a field of view separation device, spectrometers of different wavebands from visible light to long-wave infrared, and detectors corresponding to the wavebands; wherein the image scanning mirror 2 is a cylindrical body with a right-angled triangular cross section, which is provided with a central optical axis 0 inside, the image scanning mirror 2 can move in parallel along the central optical axis 0 or rotate horizontally to form rectangular fields of view of different directions and different angles;

[0038] Light from a rectangular area on the ground is converged to the image scanning mirror 2 through the telescope system 1 to form multiple rectangular fields of view at different positions, and then is spectrally imaged by the spectrometers of different wavebands from visible light to long-wave infrared through the field of view separation device, and finally is received by the detectors corresponding to the wavebands; the telescope system 1 adopts a design of intermediate primary imaging and three-time insertion of the central hole of the mirror, comprising a focal plane compensation mirror 1-5, the focal plane compensation mirror 1-5 cooperates with the image scanning mirror 2 to move to compensate for the difference in image plane position, and picture frame type hyperspectral full-waveband imaging is realized. Preferably, reference Figure 1The telescope system 1 adopts intermediate primary imaging, light path three-time insertion mirror center hole design, and comprises a primary mirror 1-1, a secondary mirror 1-2, a field-of-view external stray light diaphragm 1-3, a three-mirror 1-4, a focal plane compensation mirror 1-5, and a stray light elimination diaphragm 1-6. The field-of-view external stray light diaphragm 1-3 is located between the primary mirror 1-1 and the focal plane compensation mirror 1-5 and along the center hole of the optical axis. The stray light elimination diaphragm 1-6 is located at the center hole of the three-mirror 1-4 along the optical axis. The surface field-of-view light is converged by the primary mirror 1-1 and the secondary mirror 1-2 to the field-of-view external stray light diaphragm 1-3 for re-convergence, and then is folded by 180 degrees by the focal plane compensation mirror 1-5, passes through the stray light elimination diaphragm 1-6, and is reflected to the image side scanning mirror 2 through the center hole of the three-mirror 1-4.

[0039] Preferably, referring to Figure 1 The field-of-view separation device comprises a visible light-short wave infrared field-of-view separation device 3-1 and a medium wave-long wave infrared field-of-view separation device 3-2. The visible light-long wave infrared spectrometer system comprises a visible near infrared spectrometer 4-1, a short wave infrared spectrometer 4-2, a medium wave infrared spectrometer 4-3, and a long wave infrared spectrometer 4-4. The detector comprises a visible near infrared detector 5-1, a short wave infrared detector 5-2, a medium wave infrared detector 5-3, a long wave infrared detector 5-4, and a high-resolution area array staring panchromatic detector 5-5.

[0040] Preferably, referring to Figure 1 and Figure 6 The field-of-view separation device comprises a visible light-short wave infrared field-of-view separation device 3-1 and a medium wave-long wave infrared field-of-view separation device 3-2. The visible light-long wave infrared spectrometer system comprises a visible near infrared spectrometer 4-1, a short wave infrared spectrometer 4-2, a medium wave infrared spectrometer 4-3, and a long wave infrared spectrometer 4-4. The detector comprises a visible near infrared detector 5-1, a short wave infrared detector 5-2, a medium wave infrared detector 5-3, a long wave infrared detector 5-4, and a high-resolution area array staring panchromatic detector 5-5. Figure 6For the imaging process diagram of the present application, the image scanning mirror 2 moves uniformly along the central optical axis 0, and can form a first direction field of view 6-1 and a second direction field of view 6-2; the image scanning mirror 2 rotates 180° along the central optical axis 0, and then moves reversely along the central optical axis 0, and can form a third direction field of view 6-3; each direction field of view contains three light fields of different angles: a first angle field of view light ①, a second angle field of view light ② and a third angle field of view light ③. The first direction field of view 6-1 is directly received by a high-resolution area array staring panchromatic detector 5-5, and high-resolution staring imaging mode is realized; the second direction field of view 6-2 is split by a visible light-short wave infrared field separation device 3-1, and then enters a visible near infrared spectrometer 4-1 and a short wave infrared spectrometer 4-2, and is received by a visible near infrared detector 5-1 and a short wave infrared detector 5-2, respectively, and visible to short wave infrared band along track different angle field of view hyperspectral imaging is realized; the third direction field of view 6-3 is split by a medium wave-long wave infrared field separation device 3-2, and then enters a medium wave infrared spectrometer 4-3 and a long wave infrared spectrometer 4-4, and is received by a medium wave infrared detector 5-3 and a long wave infrared detector 5-4, respectively, and medium wave to long wave infrared band along track different angle field of view hyperspectral imaging is realized; and the above-mentioned frame type realizes high-resolution staring imaging and acquisition of visible light-short wave infrared-medium wave infrared-long wave infrared hyperspectral full wave band ground information.

[0041] Preferably, referring to Figure 1 , the visible near infrared spectrometer 4-1 and the short wave infrared spectrometer 4-2 can adopt a telescope focal plane common field of view layout, the visible light-short wave infrared field separation device 3-1 includes a visible light-short wave infrared long slit diaphragm 3-1-1 and a visible light-short wave dichroic filter 3-1-2; the medium wave infrared spectrometer 4-3 and the long wave infrared spectrometer 4-4 adopt a telescope focal plane common field of view layout, and then the medium wave-long wave infrared field separation device 3-2 includes a medium wave-long wave infrared long slit diaphragm 3-2-1 and a medium wave-long wave dichroic filter 3-2-2. The thickness of each dichroic filter is not more than 0.1 mm.

[0042] Preferably, referring to Figure 2 , the visible near infrared spectrometer 4-1 and the short wave infrared spectrometer 4-2 can also adopt a telescope focal plane split field of view layout, and then the visible light-short wave infrared field separation device 3-1 includes a visible light-short wave infrared double long slit diaphragm 3-1-3 and a visible light-short wave dichroic filter 3-1-4; the medium wave infrared spectrometer 4-3 and the long wave infrared spectrometer 4-4 adopt a telescope focal plane split field of view layout, and then the medium wave-long wave infrared field separation device 3-2 includes a medium wave-long wave infrared double long slit diaphragm 3-2-3 and a medium wave-long wave dichroic filter 3-2-4. The thickness of each dichroic filter is not more than 0.1 mm.

[0043] Preferably, referring to Figure 3 , the visible near-infrared spectrometer 4-1 and the short-wave infrared spectrometer 4-2 can also adopt a split-field layout in front of the telescope focal plane, and the visible-short-wave infrared field separation device 3-1 includes a visible long-slit diaphragm 3-1-5, a short-wave infrared turning mirror 3-1-6, and a short-wave infrared long-slit diaphragm 3-1-7; the medium-wave infrared spectrometer 4-3 and the long-wave infrared spectrometer 4-4 adopt a split-field layout in front of the telescope focal plane, and the medium-wave-long-wave infrared field separation device 3-2 includes a medium-wave long-slit diaphragm 3-2-5, a long-wave infrared turning mirror 3-2-6, and a long-wave infrared long-slit diaphragm 3-2-7.

[0044] Preferably, referring to Figure 4 , a position adjustment turning mirror 7 can also be arranged in front of the image side scanning mirror 2, so that the uniform scanning direction of the image side scanning mirror 2 is perpendicular to the central optical axis 0.

[0045] Preferably, referring to Figures 1-4 , the focal plane compensation mirror 1-5 is a plane mirror or a curved mirror, which can ensure that the focal length of the system does not change before and after the compensation movement; the focal plane compensation mirror 1-5 cooperates with the image side scanning mirror 2 to move along the central optical axis 0 of the scanning mirror at a certain speed ratio, which is used to compensate for the position difference of the image plane of the telescope deviating from the slit diaphragm in the field separation device caused by the movement of the image side scanning mirror 2 along the track, and under the premise of ensuring high image quality and frame scanning hyperspectral imaging, the image plane of the telescope 1 always remains coplanar translation at any moment. The speed ratio of the image side scanning mirror 2 and the focal plane compensation mirror 1-5 along the optical axis is preferably 2:1. If the focal plane compensation mirror 1-5 is a plane mirror, the telescope system 1 is a coaxial three-mirror structure, which can ensure that the focal length of the system does not change before and after the compensation movement; if the focal plane compensation mirror 1-5 is a curved mirror, the telescope system 1 is a coaxial four-mirror structure, although the focal length of the system changes along the optical axis, but this method can still be used for focal plane position compensation.

[0046] Preferably, referring to Figure 5 , the visible near-infrared spectrometer 4-1, the short-wave infrared spectrometer 4-2, the medium-wave infrared spectrometer 4-3, and the long-wave infrared spectrometer 4-4 all include a first mirror 8-1, a grating 8-2, a second mirror 8-3, a correction lens 8-4, and a spectrometer turning mirror 8-5; the light after the field separation device enters the corresponding spectrometer, and is received by the detector after passing through the respective correction lens, first mirror, grating, second mirror, correction lens, and spectrometer turning mirror.

[0047] In order to more clearly describe the embodiments, specific technical indexes involved in the embodiments are listed herein, and considering that the spectrometer and the main optical system are respectively modular ideal imaging modules, system integration can be realized only by simple docking, so the example indexes only list the main optical system and the image side scanning system design indexes. The specific technical indexes are as follows:

[0048] Satellite orbit height: 36000km;

[0049] Spectral range: visible near infrared 0.4μm~1.0μm; short wave infrared 1.0μm~2.5μm; medium wave infrared 3.0μm~5.0μm; long wave infrared 8.0μm~12.5μm;

[0050] Spatial resolution: 10m for panchromatic channel; 50m for visible near infrared; 100m for short wave; 100m for medium wave; 200m for long wave;

[0051] Telescope clear aperture: 3000mm;

[0052] Relative aperture: 1:3.74;

[0053] Focal length: 11240mm;

[0054] Swath field of view: 400km (0.6366°);

[0055] Image side scanning field of view: 400km (0.6366°);

[0056] Formed frame type hyperspectral field of view: 400km×400km (0.6366°×0.6366°);

[0057] The specific design parameters are shown in Table 1.

[0058] Table 1

[0059]

[0060] d1: distance from the main mirror 1-1 to the secondary mirror 1-2;

[0061] d2: distance from the secondary mirror 1-2 to the tertiary mirror 1-4;

[0062] d3: distance from the tertiary mirror 1-4 to the focal plane compensating mirror 1-5, which reflects the movement amount of the focal plane compensating mirror 1-5;

[0063] d4: distance from the focal plane compensating mirror 1-5 to the vertex of the tertiary mirror 1-4;

[0064] d4: distance from the vertex of the tertiary mirror 1-4 to the image plane scanning mirror 2, which reflects the movement amount of the image plane scanning mirror 2;

[0065] Δ1: is the moving amount of the focal plane compensation mirror 1-5 relative to the position of the high-resolution panchromatic channel when the focal plane is kept in the same plane and the image quality is not changed during the scanning of the first angle field of view light ①, the second angle field of view light ② and the third angle field of view light ③ by the image scanning mirror 2;

[0066] Δ2: is the moving amount of the image scanning mirror 2 relative to the position of the high-resolution panchromatic channel during the scanning of the first angle field of view light ①, the second angle field of view light ② and the third angle field of view light ③ by the image scanning mirror 2;

[0067] R1: is the radius of curvature of the primary mirror 1-11;

[0068] R2: is the radius of curvature of the secondary mirror 1-2;

[0069] R3: is the radius of curvature of the tertiary mirror 1-4;

[0070] k: is the mirror surface conic coefficient;

[0071] a1: is the 4th order aspheric surface coefficient of the mirror surface;

[0072] a2: is the 6th order aspheric surface coefficient of the mirror surface;

[0073] a3: is the 8th order aspheric surface coefficient of the mirror surface;

[0074] Along-track field of view ①: 0.3183°; along-track field of view ②: 0°; along-track field of view ③: -0.3183°;

[0075] In the present application, the selected spectrometer and the size of the detector pixel index are shown in Table 2 as follows:

[0076] Table 2

[0077]

[0078] According to the embodiments of the present application, the stray light stop 1-3 is located between the primary mirror 1-1 and the focal plane compensation mirror 1-5 and at the center hole along the optical axis; the stray light stop 1-6 is located at the center hole of the tertiary mirror along the optical axis; the image scanning mirror 2 is located behind the tertiary mirror 1-4; the telescope adopts intermediate primary imaging and optical path three times through the center hole of the mirror, as shown in Figure 1 .

[0079] Referring to Figure 6 , Figure 6This is a diagram of the imaging process of a frame-type hyperspectral full-band imaging system based on image-space scanning of the present invention. According to the embodiment of the present application, the image-space scanning mirror 2 and the focal plane compensation mirror 1-5 are located in the first direction field of view 6-1, and the first angle field of view light ①, the second angle field of view light ② and the third angle field of view light ③ are directly received by the high-resolution area array staring panchromatic detector 5-4, realizing a high-resolution staring imaging mode, achieving 400km with a spatial resolution of 10m 400km field-of-view staring monitoring.

[0080] According to an embodiment of the present application, the image-side scanning mirror 2 moves in a straight line at a uniform speed along the central optical axis 0, and moves from the first direction field of view 6-1 to the second direction field of view 6-2. The first angle field of view light ①, the second angle field of view light ② and the third angle field of view light ③ are separated by the visible light-short-wave infrared field of view separation device 3-1 and enter the visible near-infrared spectrometer 4-1 and the short-wave infrared spectrometer 4-2, and are respectively received by the visible near-infrared detector 5-1 and the short-wave infrared detector 5-2, thereby realizing high-spectral imaging of different angles of view along the track in the visible to short-wave infrared band in a frame-type manner.

[0081] According to an embodiment of the present application, the image-side scanning mirror 2 is located in the first direction field of view 6-1, rotates horizontally 180° along the central optical axis 0, and then moves in a straight line at a uniform speed in the opposite direction along the central optical axis 0 to form a third direction field of view 6-3. The first angle field of view light ①, the second angle field of view light ②, and the third angle field of view light ③ are separated by the medium-wave-long-wave infrared field of view separation device 3-2 and enter the medium-wave infrared spectrometer 4-3 and the long-wave infrared spectrometer 4-4, and are respectively received by the medium-wave infrared detector 5-3 and the long-wave infrared detector 5-4, thereby realizing high-spectral imaging of different angles of view along the track in the medium-wave to long-wave infrared band in a frame-type manner.

[0082] According to an embodiment of the present application, the movement amount of the image-side scanning mirror 2 is twice the movement amount of the focal plane compensation mirrors 1-5, and the movement speed is also twice as much, as shown in Table 3 below.

[0083] Table 3

[0084]

[0085] Note: When the signs of Δ1 and Δ2 are opposite, it means that the image-side scanning mirror (2) and the focal plane compensation mirror (1-5) move in the same direction along the optical axis (0).

[0086] The frame type hyperspectral full waveband imaging system telescope based on image scanning of the application adopts intermediate primary imaging, three times of light path insertion mirror center hole design; the image scanning mirror moves uniformly along the optical axis to realize frame type signal collection along the track of different fields of view, the focal plane compensation mirror performs focal plane position compensation along the optical axis to ensure that the telescope image plane is coplanar at any time, and then the slit is sequentially entered into the spectrometer to obtain the ground frame type hyperspectral information; the method will overturn the current situation that large aperture high resolution multispectral and hyperspectral loads rely on satellite platform for image shift compensation and frame imaging, and lay a foundation for high resolution area array staring imaging + full waveband frame type hyperspectral and multispectral comprehensive detection, and the high resolution panchromatic channel 0.3183°~0.3183° area field of view MTF evaluation diagram is given through optical design software simulation, as shown in Figure 7 The MTF of the panchromatic channel 0.3183°~0.3183° area field of view can still be greater than 0.35 at a high spatial frequency corresponding to 133.33 black and white line pairs per millimeter, and the performance is better. And the MTF diagram (a) corresponding to the scanning starting field of view 0.3183° of the visible spectrometer, the short wave infrared spectrometer, the medium wave infrared spectrometer and the long wave infrared spectrometer, and the MTF diagram (b) corresponding to the scanning ending field of view-0.3183° are given, and details are shown in Figures 8 to 11 It can be seen that: when the visible short wave spectrometer, the short wave infrared spectrometer, the medium wave spectrometer and the long wave infrared spectrometer are scanned from 0.3183° to-0.3183° to form a frame type hyperspectral image by using the image scanning method proposed in the application, the MTF of diagram (a) and diagram (b) is basically equal (deviation ≤0.05). The frame type full waveband high quality hyperspectral spectral data can be obtained by the image scanning method, the bottleneck problem of frame type multispectral and hyperspectral data acquisition depending on the satellite platform is solved, and the feasibility of the system method is proved combined with the design example, which provides important engineering technical support for frame type full waveband multispectral and hyperspectral monitoring + high resolution staring search in a stationary orbit, and high resolution high sensitivity hyperspectral detection in a non-stationary orbit.

[0087] The above described specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the application, and it should be understood that the above described is only a specific embodiment of the application and is not used to limit the application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A frame-type hyperspectral full-band imaging system based on image-space scanning, characterized in that: The system comprises a telescope system (1), an image-side scanning mirror (2), a field of view separation device, a spectrometer for different wavelengths from visible light to long-wave infrared, and a detector for the corresponding wavelengths; wherein the image-side scanning mirror (2) is in the shape of a cylinder with a right-angled triangular cross-section, and is provided with a central optical axis (0) therein; the image-side scanning mirror (2) can move parallel to the central optical axis (0) or rotate horizontally to form a rectangular field of view in different directions and angles; Light from a rectangular area on the surface of the earth is converged by the telescope system (1) to the image-side scanning mirror (2), forming multiple rectangular fields of view at different positions. After passing through the field of view separation device, the light is separated and imaged by spectrometers of different wavelengths, such as visible light and long-wave infrared, and finally received by detectors of corresponding wavelengths. The telescope system (1) adopts a design of intermediate one-time imaging and three-time interlaced reflector center hole of the optical path, and includes a focal plane compensation mirror (1-5). The focal plane compensation mirror (1-5) and the image side scanning mirror (2) move in coordination to compensate for the image plane position difference, thereby realizing frame-type hyperspectral full-band imaging.

2. The image-space scanning-based full-band hyperspectral imaging system according to claim 1, characterized in that: The telescope system (1) further comprises a primary reflector (1-1), a secondary reflector (1-2), an out-of-field stray light diaphragm (1-3), a third reflector (1-4), and a stray light elimination diaphragm (1-6). The out-of-field stray light diaphragm (1-3) is located between the primary reflector (1-1) and the focal plane compensation mirror (1-5) and along the center hole of the optical axis; the stray light elimination diaphragm (1-6) is located along the center hole of the optical axis of the third reflector (1-4); the field of view light is converged to the out-of-field stray light diaphragm (1-3) via the primary reflector (1-1) and the secondary reflector (1-2), then deflected 180 degrees along the axis via the focal plane compensation mirror (1-5), passes through the stray light elimination diaphragm (1-6), passes through the center hole of the third reflector (1-4), and then illuminates the image side scanning mirror (2).

3. The image-space scanning-based full-band hyperspectral imaging system according to claim 1, characterized in that: The field of view separation device comprises a visible light-short wave infrared field of view separation device (3-1) and a medium wave-long wave infrared field of view separation device (3-2); the visible light-long wave infrared spectrometer system comprises a visible near infrared spectrometer (4-1), a short wave infrared spectrometer (4-2), a medium wave infrared spectrometer (4-3), and a long wave infrared spectrometer (4-4); and the detector comprises a visible near infrared detector (5-1), a short wave infrared detector (5-2), a medium wave infrared detector (5-3), a long wave infrared detector (5-4), and a high-resolution array staring panchromatic detector (5-5).

4. The image-space scanning-based full-band hyperspectral imaging system according to claim 1, wherein: The image-side scanning mirror (2) moves linearly at a uniform speed along the central optical axis (0) to form a first-direction field of view (6-1) and a second-direction field of view (6-2); the image-side scanning mirror (2) rotates horizontally 180° along the central optical axis (0) and then moves linearly at a uniform speed in the opposite direction along the central optical axis (0) to form a third-direction field of view (6-3); each directional field of view contains three light fields of view at different angles.

5. The image-space scanning-based full-band hyperspectral imaging system according to claim 3 or 4, characterized in that: The first-direction field of view (6-1) is directly received by the high-resolution array staring panchromatic detector (5-5), realizing a high-resolution staring imaging mode; the second-direction field of view (6-2) is separated by the visible light-short-wave infrared field of view separation device (3-1) and then enters the visible near-infrared spectrometer (4-1) and the short-wave infrared spectrometer (4-2), and is respectively received by the visible near-infrared detector (5-1) and the short-wave infrared detector (5-2), realizing hyperspectral imaging of fields of view at different angles along the track in the visible to short-wave infrared band; the third-direction field of view (6-3) is separated by the medium-wave-long-wave infrared field of view separation device (3-2) and then enters the medium-wave infrared spectrometer (4-3) and the long-wave infrared spectrometer (4-4), and is respectively received by the medium-wave infrared detector (5-3) and the long-wave infrared detector (5-4), realizing hyperspectral imaging of fields of view at different angles along the track in the medium-wave to long-wave infrared band.

6. The image-space scanning-based full-band hyperspectral imaging system according to claim 3, characterized in that: When the visible-near-infrared spectrometer (4-1) and the short-wave infrared spectrometer (4-2) adopt a telescope focal plane common field of view layout, the visible-short-wave infrared field of view separation device (3-1) includes a visible-short-wave infrared long slit diaphragm (3-1-1) and a visible-short-wave color separation plate (3-1-2); when the medium-wave infrared spectrometer (4-3) and the long-wave infrared spectrometer (4-4) adopt a telescope focal plane common field of view layout, the medium-wave-long-wave infrared field of view separation device (3-2) includes a medium-wave-long-wave infrared long slit diaphragm (3-2-1) and a medium-wave-long-wave color separation plate (3-2-2).

7. The image-space scanning-based full-band hyperspectral imaging system according to claim 3, characterized in that: When the visible-near infrared spectrometer (4-1) and the short-wave infrared spectrometer (4-2) adopt a telescope focal plane field-of-view layout, the visible-short-wave infrared field-of-view separation device (3-1) includes a visible-short-wave infrared double-long slit diaphragm (3-1-3) and a visible-short-wave color separation plate (3-1-4); when the medium-wave infrared spectrometer (4-3) and the long-wave infrared spectrometer (4-4) adopt a telescope focal plane field-of-view layout, the medium-wave-long-wave infrared field-of-view separation device (3-2) includes a medium-wave-long-wave infrared double-long slit diaphragm (3-2-3) and a medium-wave-long-wave color separation plate (3-2-4).

8. The image-space scanning-based full-band hyperspectral imaging system according to claim 3, characterized in that: When the visible-near infrared spectrometer (4-1) and the short-wave infrared spectrometer (4-2) adopt a telescope focal plane field separation layout, the visible light-short-wave infrared field separation device (3-1) includes a visible long slit diaphragm (3-1-5), a short-wave infrared deflection mirror (3-1-6), and a short-wave infrared long slit diaphragm (3-1-7); when the medium-wave infrared spectrometer (4-3) and the long-wave infrared spectrometer (4-4) adopt a telescope focal plane field separation layout, the medium-wave-long-wave infrared field separation device (3-2) includes a medium-wavelength slit diaphragm (3-2-5), a long-wave infrared deflection mirror (3-2-6), and a long-wave infrared long slit diaphragm (3-2-7).

9. The image-space scanning-based full-band hyperspectral imaging system according to claim 1, characterized in that: A position adjustment turning mirror (7) may also be provided in front of the image-side scanning mirror (2) so that the uniform scanning direction of the image-side scanning mirror (2) is perpendicular to the central optical axis (0).

10. The image-space scanning-based full-band hyperspectral imaging system according to any one of claims 1 to 9, characterized in that: The focal plane compensation mirror (1-5) is a plane or curved mirror, which cooperates with the image side scanning mirror (2) to move at a constant speed along the central optical axis (0) of the scanning mirror at a preset speed ratio, and is used to compensate for the position difference of the telescope image plane deviating from the slit diaphragm in the field of view separation device caused by the motion of the image side scanning mirror (2) along the track, so that the image plane of the telescope (1) always maintains coplanar translation at any time under the premise of ensuring high image quality frame scanning and high spectrum imaging.

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