A time delay integration based space-borne hyperspectral imaging system and method

Abstract

The application discloses a kind of spaceborne hyperspectral imaging system and method based on time delay integration, it is related to hyperspectral imaging technical field.System includes front telescope system, optical fiber array, light splitting system and time delay integration detector;Front telescope system collects ground scene light beam and is imaged on front image surface, is divided into visible near infrared and short wave infrared band by beam splitter;Corresponding each band, optical fiber array is accepted the image of front image surface by incident end microlens array, forms multiple optical fiber slits by rearrangement;Light splitting system receives exit light beam by exit end microlens array and light splitting forms spectral image surface;Time delay integration detector is set at spectral image surface, with multiple photosensitive surface regions respectively with multiple optical fiber slits correspond, by time delay integration accumulation signal electron, output high signal-to-noise ratio spectral image data.The application is through optical fiber array rearrangement and time delay integration accumulation to improve signal-to-noise ratio, give consideration to high space and high spectral resolution.

Description

Technical Field

[0001] This invention relates to the field of hyperspectral imaging technology, and in particular to a spaceborne hyperspectral imaging system and method based on time delay integration. Background Technology

[0002] Hyperspectral imaging technology can acquire continuous spectral curves of targets. Compared with multispectral imaging technology, which can only acquire discrete band data, it can extract richer target fingerprint features, and has significant advantages in fields such as land cover classification and target recognition. In terms of working platform, hyperspectral imaging mainly has two forms: spaceborne and airborne. Among them, the spaceborne method has a large observation range, can achieve global coverage, and does not need to enter the airspace of other countries.

[0003] Currently, various spaceborne hyperspectral imaging systems have been developed both domestically and internationally.

[0004] The hyperspectral imager on China's Tiangong-1 space station employs a composite prism beam splitting technique to improve light energy utilization and introduces a pointing mirror motion compensation mechanism to extend the integration time. The imager has a spatial resolution of 10m and a spectral resolution of approximately 10nm in the visible near-infrared (VNIR) band, with a swath width of 10km; and a spatial resolution of 20m and a spectral resolution of approximately 23nm in the short-wave infrared (SWIR) band, with a swath width of 10km. The system's spatial resolution is on the order of 10m, but its spectral resolution has not yet reached 5nm.

[0005] The Spaceborne Hyperspectral Applicable Land and Ocean Mission (SHALOM), utilizing an agile satellite platform, increases integration time to four times that of conventional methods and is equipped with a large-aperture, low-F-number optical system. Its spatial resolution is better than 10m, swath width is greater than 10km, spectral coverage is 0.4-2.5μm, and spectral resolution is 10nm. However, this system still has limitations in terms of 1m-level spatial resolution and 5nm-level spectral resolution.

[0006] The French Hyperspectral X Imagery (HYPXIM) is developed based on the Agile satellite platform. Its forward telescope system employs a three-mirror structure, and its spectroscopic system uses a prism dispersion scheme. The system has a swath width of 16 km, a spatial resolution of 8 m, a spectral coverage of 0.4–2.5 μm, and a spectral resolution of 10 nm. However, its spatial resolution does not exceed 5 m, and its spectral resolution does not reach 5 nm.

[0007] The Advanced Responsive Tactically Effective Military Imaging Spectrometer (ARTEMIS) aboard the US TacSat-3 satellite employs a two-mirror front-mounted telescope system and an Offner convex grating-based beam splitting system. This system achieves a spatial resolution of 4m / 5m, a spectral coverage of 0.4-2.5μm, and a spectral resolution of 5nm. However, due to the lower diffraction efficiency in the violet band, the system's signal-to-noise ratio is limited, affecting image quality and preventing a breakthrough to 1m-level spatial resolution.

[0008] China's Beijing-3B satellite, based on the enhanced agile satellite platform CAST3000E, features the Tianshu camera, a primary payload that achieves panchromatic resolution of 0.5m, multispectral resolution of 2m, and swath width of 11km. While this satellite boasts meter-level spatial resolution, its use of a multispectral imaging mechanism, which only configures discrete spectral ranges, prevents the acquisition of continuous hyperspectral curves and thus fails to meet the demands of hyperspectral remote sensing for detailed spectral information.

[0009] The above analysis reveals a trade-off between high spatial resolution and high spectral resolution in existing spaceborne imaging systems: systems with hyperspectral imaging capabilities typically achieve spatial resolutions above the meter level; systems with meter-level spatial resolution, however, are limited by multispectral mechanisms and cannot acquire continuous spectral information. In traditional pushbroom imaging mode, achieving 1-meter spatial resolution, 5-nm spectral resolution, and high signal-to-noise ratio simultaneously, constrained by signal-to-noise ratio and detector frame rate, places stringent demands on the optical system aperture and detector performance, making engineering implementation quite challenging.

[0010] To address the aforementioned issues, this invention proposes a spaceborne hyperspectral imaging system and method based on time-delay integration. By rearranging the front image plane using an optical fiber array and combining it with the signal accumulation mechanism of the time-delay integration detector, the signal-to-noise ratio is effectively improved in pushbroom scanning imaging mode, thereby achieving both high spatial resolution and high spectral resolution imaging requirements with a smaller optical system aperture. Summary of the Invention

[0011] To address this, embodiments of the present invention provide a spaceborne hyperspectral imaging system and method based on time delay integration, which solves the problems of difficulty in achieving both high spatial resolution and hyperspectral resolution and insufficient signal-to-noise ratio in the prior art.

[0012] To address the aforementioned technical problems, embodiments of the present invention provide a spaceborne hyperspectral imaging system based on time-delay integration, comprising:

[0013] A front-view telescope system is used to collect a beam of light from ground objects and image the ground objects onto a front-view image plane; the front-view telescope system includes a beam splitter that splits the beam of light into a visible and near-infrared band and a short-wave infrared band.

[0014] An incident end microlens array, including a first incident end microlens array and a second incident end microlens array, is used to improve the fiber array fill factor.

[0015] The fiber array includes a first fiber array and a second fiber array, which respectively receive the images of the front image plane of the corresponding band through the first incident end microlens array and the second incident end microlens array, and rearrange the respective images to form multiple fiber optic slits.

[0016] The output microlens array, including a first output microlens array and a second output microlens array, is used to correct the focal ratio of the fiber-exported beam.

[0017] The beam splitting system includes a first beam splitting system and a second beam splitting system, which respectively receive beams emitted from corresponding multiple fiber optic slits through the first output end microlens array and the second output end microlens array, and split the beams to form a spectral image plane.

[0018] The time-delay integration detector includes a first time-delay integration detector and a second time-delay integration detector, which are respectively disposed at the spectral image plane of the first beam splitting system and the second beam splitting system. Each of them has multiple photosensitive surface regions, which correspond to multiple fiber optic slits. They are used to accumulate signal electrons through time-delay integration and output high signal-to-noise ratio spectral image data.

[0019] Preferably, the first fiber array and the second fiber array each include a close-packed array, a fiber image transmission bundle, and a fiber slit group connected in sequence; the close-packed array is used to receive the image of the front image plane; the fiber image transmission bundle is used to transmit the image received by the close-packed array to the fiber slit group and rearrange it; the fiber slit group is composed of the multiple fiber slits formed by the rearrangement.

[0020] Preferably, the optical fibers in the close-packed array are arranged in multiple columns in the track-crossing direction and in multiple rows in the track-following direction; the integration order of the corresponding time delay integration detector is equal to the number of rows in the track-following direction of the close-packed array.

[0021] Preferably, each column of the close-packed array is divided into multiple groups; in the fiber optic slit group, the columns of fibers in the same group are arranged at intervals, and the interval is not less than the width of the spectral image plane formed by a single column of fiber after passing through the beam splitting system in the dispersion direction, and the fibers in columns of the same order in different groups are combined to form the same fiber optic slit.

[0022] Preferably, the arrangement of each column of optical fibers in the same group within the optical fiber slit group corresponds to the same photosensitive surface region of the time delay integration detector; there is a physical interval between adjacent photosensitive surface regions of the time delay integration detector.

[0023] Preferably, the first incident microlens array and the second incident microlens array are square close-packed microlens arrays; the first exiting microlens array and the second exiting microlens array each include a first lens and a second lens, the first lens collimates the fiber-emitting beam into a parallel beam and images the fiber core onto the intermediate pupil plane, and the second lens focuses the parallel beam onto the image-side focal plane, and the fiber-emitting focal ratio is controlled by adjusting the focal length ratio of the first lens and the second lens.

[0024] Preferably, the first time delay integral detector and the second time delay integral detector are each composed of multiple detectors spliced ​​together, and each detector contains multiple photosensitive surface areas.

[0025] Preferably, the spectral image planes formed by the first spectral system and the second spectral system each have long-wavelength spectral lines at one end and short-wavelength spectral lines at the other end in the dispersion direction.

[0026] Preferably, the front image plane has an image plane movement direction along the track direction, the time delay integration detector has a charge accumulation direction, and the image plane movement direction is consistent with the charge accumulation direction.

[0027] This invention also provides a spaceborne hyperspectral imaging method based on time-delay integration. This method employs the aforementioned spaceborne hyperspectral imaging system based on time-delay integration, and specifically includes:

[0028] S1. A beam of light from ground objects is collected by a front-view telescope system, and the beam is split into visible and near-infrared bands and short-wave infrared bands by a beam splitter, and then imaged onto the corresponding front-view image planes respectively.

[0029] S2. For each band, after passing through the incident end microlens array, the image of the corresponding front image plane is received by the fiber array, and the image is rearranged to form multiple fiber optic slits.

[0030] S3. The beam emitted from the multiple fiber optic slits is received by the microlens array at the output end, and the beam is split by using the multiple fiber optic slits as the entrance slits of the beam splitting system to form a spectral image plane.

[0031] S4. The spectral image plane is received by a time-delay integration detector, which has multiple photosensitive surface regions, each of which corresponds to a multiple fiber optic slits. The signal electrons are integrated and accumulated over time delay to output high signal-to-noise ratio spectral image data.

[0032] As can be seen from the above technical solutions, this invention application has the following beneficial effects:

[0033] This invention rearranges the front image plane using an optical fiber array and combines this with multiple accumulations of signal electrons by a time-delay integral detector, effectively improving the system's signal-to-noise ratio. This enables a meter-level aperture optical system to achieve hyperspectral imaging with 1-meter spatial resolution. It achieves continuous, uninterrupted imaging in pushbroom scanning mode, balancing high spatial and spectral resolution. By using microlens arrays at the incident and exit ends to improve the fiber array fill factor and correct the fiber exit focal ratio, light energy loss is reduced, ensuring the system's high signal-to-noise ratio imaging performance. Data processing is simple, making it applicable to urban environmental remote sensing, coastal zone environmental monitoring, and national defense applications. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Referring to the drawings will make the features and advantages of the present invention clearer. The drawings are illustrative and should not be construed as limiting the present invention in any way. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0035] Figure 1 This is a schematic diagram illustrating the implementation principle of a spaceborne hyperspectral imaging system based on time delay integration provided by the present invention.

[0036] Figure 2 This is a schematic diagram of the fiber optic array arrangement in this invention;

[0037] Figure 3 This is a schematic diagram of the coupling between the fiber optic slit and the beam splitting system in this invention;

[0038] Figure 4 This is a schematic diagram illustrating the working principle of the time delay integration detector in this invention;

[0039] Figure 5 This is a schematic diagram of the overall system scheme in this invention;

[0040] Figure 6 This is a signal-to-noise ratio curve in the visible and near-infrared bands of this invention;

[0041] Figure 7 This is a signal-to-noise ratio curve of the shortwave infrared band in this invention;

[0042] Figure 8 This is a schematic diagram of the microlens structure at the emission end in this invention;

[0043] Figure 9 This is a flowchart of a spaceborne hyperspectral imaging method based on time delay integration provided by the present invention.

[0044] Explanation of reference numerals in the accompanying drawings: 0101, Track crossing direction; 0102, Track-side direction; 0103, Ground field of view area; 0104, Ground scene stripe; 0105, Ground sampling interval along the track direction; 0106, Field of view along the track direction; 0107, First reflecting mirror; 0108, Second reflecting mirror; 0109, Front image plane; 0110, Fiber optic array; 0110a, First fiber optic array; 0110b, Second fiber optic array; 01101, Close-packed array; 0 1102, Fiber optic image bundle; 01103, Fiber optic slit group; 01103a, First fiber optic slit group; 01103b, Second fiber optic slit group; 0111, Beam splitting system; 0111a, First beam splitting system; 0111b, Second beam splitting system; 0201, Integrating order; 0202, Fiber optic slit; 0203, Physical spacing of photosensitive surfaces; 0204, Spectral image plane; 0204a, First spectral image plane; 0204b, Second spectral image plane; 0205 0206. Fiber optic slit length; 0207. First group of photosensitive surfaces; 0208. Second group of photosensitive surfaces; 0209. Third group of photosensitive surfaces; 0210. Fourth group of photosensitive surfaces; 0211. Fifth group of photosensitive surfaces; 0212. Sixth group of photosensitive surfaces; 0213. Direction of front image plane movement; 0214. Dispersion direction; 0215. Charge accumulation direction of time-delay integration detector; 0216. Long-wavelength spectral lines; 0217. Short-wavelength spectral lines; 0308. Detector; 0309. Spectral image. Surface region; 0401, detector potential well; 0402, potential well depth; 0403, scene image point; 0404, spectral image point; 0501, front-view telescope system; 0502, beam splitter; 0503, incident microlens array; 0503a, first incident microlens array; 0503b, second incident microlens array; 0504, exit microlens array; 0504a, first exit microlens array; 0504b, second exit microlens array; 0601, first time-delay integration detector; 0602, second time-delay integration detector; L1, first lens; L2, second lens. Detailed Implementation

[0045] 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, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Example 1:

[0047] This embodiment provides a spaceborne hyperspectral imaging system based on time delay integration.

[0048] like Figure 5 As shown, the system includes a front-view telescope system 0501, a beam splitter 0502, an incident microlens array 0503, an optical fiber array 0110, an exiting microlens array 0504, a beam splitting system, and a time-delay integration detector. The beam splitter 0502 is located inside the front-view telescope system 0501. The incident microlens array 0503 and the exiting microlens array 0504 are respectively located at both ends of the optical fiber array 0110. The time-delay integration detector is located at the spectral image plane of the beam splitting system.

[0049] Specifically, the front-facing telescope system 0501 is used to collect beams of light from ground objects and image the ground objects onto the front-facing image plane 0109. For example... Figure 1 As shown, the front-view telescope system 0501 includes a first reflecting mirror 0107 and a second reflecting mirror 0108 for folding the optical path. The ground scene strip 0104 is located within the ground field of view 0103, which is imaged onto the front image plane 0109 after passing through the front-view telescope system 0501. Here, 0101 represents the track-crossing direction, with a span equal to the track-crossing width; 0102 represents the track-along direction; 0105 represents the ground sampling interval along the track; and 0106 represents the field of view along the track. The front-view telescope system 0501 employs an off-axis three-mirror structure.

[0050] The front-view telescope system 0501 includes a beam splitter 0502. For example... Figure 5As shown, the ground scene beam is collected by the forward telescope system 0501 and then split into a visible near-infrared (VNIR) band beam and a short-wave infrared (SWIR) band beam by the beam splitter 0502, which then enter the first beam splitting system 0111a and the second beam splitting system 0111b, respectively. For each band, an independent incident microlens array 0503, fiber array 0110, exit microlens array 0504, beam splitting system, and time delay integration detector are configured. Specifically, the VNIR band is configured with a first incident microlens array 0503a, a first fiber array 0110a, a first exit microlens array 0504a, a first beam splitting system 0111a, and a first time delay integration detector 0601; the SWIR band is configured with a second incident microlens array 0503b, a second fiber array 0110b, a second exit microlens array 0504b, a second beam splitting system 0111b, and a second time delay integration detector 0602.

[0051] The following explanation uses one band as an example to illustrate the structural composition of each component; the same applies to the other band.

[0052] like Figure 1 As shown, the fiber optic array 0110 includes a close-packed array 01101, a fiber optic image bundle 01102, and a fiber optic slit group 01103 connected in sequence. The close-packed array 01101 is located at the front image plane 0109 and is used to receive the image plane of the front system. The fiber optic image bundle 01102 is used to rearrange the image plane. Specifically, the first fiber optic array 0110a includes a first fiber optic slit group 01103a, and the second fiber optic array 0110b includes a second fiber optic slit group 01103b. The fiber optic slit group 01103 consists of multiple rearranged fiber optic slits 0202 and is coupled to the rear-end beam splitting system 0111.

[0053] The incident microlens array 0503 is positioned between the front image plane 0109 and the close-packed array 01101 to improve the fiber array fill factor. The incident microlens array 0503 is a square close-packed microlens array with a square arrangement and a fill factor greater than 0.98.

[0054] The specific arrangement of optical fibers in fiber array 0110 is as follows: Figure 2As shown. In the close-packed array 01101, the optical fibers are arranged in multiple columns in the track-crossing direction 0101 and in multiple rows in the track-following direction 0102. The integration order 0201 of the time-delay integration detector is equal to the number of rows in the track-following direction of the close-packed array 01101. Each column of the close-packed array 01101 is divided into multiple groups. In the fiber slit group 01103, the columns of optical fibers within the same group are spaced apart, with a spacing not less than the width of the spectral image plane 0204 formed by a single column of optical fiber after passing through the beam splitting system. Columns of optical fibers in the same order in different groups are combined to form the same fiber slit 0202. The arrangement position of each column of optical fiber within the same group in the fiber slit group 01103 corresponds to the same photosensitive surface region 0206 of the time-delay integration detector. There is a physical interval 0203 between each photosensitive surface region 0206-0211 of the time-delay integration detector. The length of the fiber slit 0202 is 0205.

[0055] like Figure 2 As shown, 0213 is the dispersion direction, 0212 is the forward image plane movement direction, and 0214 is the charge accumulation direction of the time-delay integration detector. The forward image plane movement direction 0212 is consistent with the charge accumulation direction 0214 of the time-delay integration detector. On the detector photosensitive surface, the long-wavelength spectral line 0215 is located at one end of the spectral image plane 0204, and the short-wavelength spectral line 0216 is located at the other end of the spectral image plane 0204.

[0056] like Figure 3 As shown, taking one of the fiber optic slits 0202 as an example, it is coupled to the back-end beam splitting system 0111. The beam emitted from the fiber optic slit 0202 is split by the beam splitting system 0111 and finally forms a corresponding spectral image region 0305 on the multiple photosensitive surfaces 0206-0211 of the detector 0304. The detector 0304 corresponds to either the first time-delay integration detector 0601 or the second time-delay integration detector 0602 in the actual system. The other fiber optic slits are treated similarly. In this embodiment, the beam splitting system uses a typical Offner beam splitting structure as an example; however, the beam splitting system can also adopt a reflective three-mirror RT structure.

[0057] The microlens array 0504 at the output end is positioned between the fiber optic slit assembly 01103 and the beam splitter system 0111 to correct the focal ratio of the fiber-embedded beam. For example... Figure 8 As shown, the output microlens array 0504 includes a first lens L1 and a second lens L2. The first lens L1 collimates the fiber output beam into a parallel beam and images the fiber core onto the central pupil plane; the second lens L2 focuses the parallel beam onto the image-side focal plane. By adjusting the focal length ratio of the first lens L1 and the second lens L2, and constraining the diameter of the second lens L2 to not exceed the pixel size, precise control of the fiber output focal ratio is achieved.

[0058] like Figure 5As shown, the beam splitting system 0111 is used to split the beam emitted from the fiber optic slit 0202 and form a spectral image plane. A first time-delay integration detector 0601 is disposed at the first spectral image plane 0204a of the first beam splitting system 0111a, and a second time-delay integration detector 0602 is disposed at the second spectral image plane 0204b of the second beam splitting system 0111b, each having multiple photosensitive surface regions (e.g., ...). Figure 2 (0206-0211 in the image), each photosensitive surface region corresponds to one of the multiple fiber optic slits 0202.

[0059] The working process of the time delay integral detector is as follows: Figure 4 As shown. Taking a column in a close-packed array as an example, 0215 on detector 0304 is the position of the long-wavelength spectral line. 0401 represents the detector potential well, and 0402 is the potential well depth of the detector at the long-wavelength spectral line 0215. The image plane moves in the direction of 0212. When the scene image point 0403 is in the first row, the corresponding spectral image point 0404 is also in the first row of the detector's photosensitive surface, and a photogenerated electron is generated in potential well 0401. When scene image point 0403 moves to the second row, spectral image point 0404 moves synchronously to the second row. At this time, a photogenerated electron is generated in the potential well of the second row, and the photogenerated electron from the previous row is synchronously transferred to the potential well of the second row. Therefore, there are two signal electrons in the potential well of the second row. When the image point moves to the fifth row, the spectral image point moves synchronously to the fifth row, a photogenerated electron is generated in the potential well, and the previously accumulated electrons are synchronously transferred in, for a total of 5 signal electrons. This allows for the accumulation of the signal electron count through time-delay integration, thereby improving the signal-to-noise ratio.

[0060] The core criterion for system signal-to-noise ratio (SNR) analysis is the SNR, defined as the ratio of the number of effective signal electrons to the number of noise electrons generated by radiation from the target object on the detector's photosensitive surface. The expression is as follows:

[0061] ;

[0062] in, Signal-to-noise ratio; The effective signal electron number; This represents the number of noise electrons.

[0063] in, The calculation formula is:

[0064] ;

[0065] ;

[0066] in, for The number of effective signal electrons received by the detector within a time period, i.e., within a single row period; The entrance pupil radiance; System transmittance; To improve the detector's detection efficiency; Wavelength; It is Planck's constant; The speed of light in a vacuum; The integration time; It is a constant; The size of the detector pixel; For the system number; This represents the number of cell merges; there are no merges here. =1; The spectral sampling interval for a single pixel; The integration order of the time delay integral detector used.

[0067] The calculation formula is:

[0068] ;

[0069] ;

[0070] ;

[0071] ;

[0072] in, Total photon shot noise; This represents the total dark noise of the detector; This represents the number of dark charges within a single row period; for The number of effective signal electrons received by the detector within a time period, i.e., within a single row period; The integration order of the time delay integral detector used;

[0073] For different frequency bands, the signal-to-noise ratio curves are as follows: Figure 6 and Figure 7 As shown. Figure 6 The signal-to-noise ratio curve for the VNIR band is shown. Figure 7 This is the signal-to-noise ratio curve for the SWIR band. Under a solar zenith angle of 30°, the average system signal-to-noise ratio is no less than 100.

[0074] The time-delay integral detector is composed of multiple detectors, each containing multiple photosensitive surface regions. In optical design, in addition to meeting system parameters, image quality evaluations such as modulation transfer function (MTF) and dot plots need to approach the diffraction limit.

[0075] The following provides an example of the parameter configuration for the system in this embodiment. The system specifications require an orbital altitude of 500km, spatial resolution of 1m, spectral resolution of 5nm, spectral coverage of 0.4-1.0μm in the VNIR band and 1.0-2.5μm in the SWIR band, a swath width of 10km, and a signal-to-noise ratio of no less than 100. Based on these system specifications, a pixel size selection analysis is conducted: a 15μm large pixel has a longer focal length and a larger F-number for the same aperture, resulting in lower optical design difficulty, but requires more beam splitting systems for the same fiber array size; a 5μm small pixel has a shorter focal length and a smaller F-number for the same aperture, significantly increasing optical design difficulty, but reducing the number of beam splitting systems. Considering both optical design difficulty and beam splitting system scale, a medium pixel size of 10μm is used as an example for scheme analysis.

[0076] Taking a 10μm pixel size as an example, the VNIR band configuration features an entrance pupil diameter of 1400mm, an F-number of 3.57, and a time delay integration order of 32; the SWIR band configuration features an entrance pupil diameter of 1500mm, an F-number of 3.33, and a time delay integration order of 64. Taking the VNIR band as an example, the front telescope system has an entrance pupil diameter of 1400mm and an F-number of 3.57, with the beam splitting system corresponding to 29 slits and a slit length of 70mm (here, the slits and spectral image planes are optically designed as continuous without gaps). A single time delay integration detector exemplarily includes 7 photosensitive surface regions, with a pixel size of 10μm and a time delay integration order of 32 (VNIR band), while the SWIR band corresponds to a time delay integration order of 64; the physical spacing between each photosensitive surface is 0.35mm. In practical engineering, due to the physical spacing between detectors and the physical spacing between photosensitive surfaces within a single detector, the required total number of detector blocks and the number of beam splitting systems need to be analyzed and adjusted adaptively based on the aforementioned spacing parameters. After comprehensive consideration, under the premise of meeting optical design constraints, 14 detector blocks are selected for splicing, with a detector spacing of 0.35mm, and 4 beam splitting systems are configured, corresponding to an actual slit length of approximately 65.3mm.

[0077] The above parameter configurations are merely illustrative. In specific engineering applications, parameters such as the number of sensor array channels, time delay integration order, number of detectors, number of beam splitters, pixel size, entrance pupil diameter, and F-number can be adaptively adjusted according to actual indicators and constraints, and do not constitute a limitation on the present invention. However, it is necessary to maintain core constraints such as the charge accumulation direction of the time delay integration detector being consistent with the forward image plane movement direction, the number of rows along the track direction of the close-packed array being equal to the integration order, and the fiber optic slit spacing matching the spectral image plane width.

[0078] The system operates in pushbroom scanning imaging mode. The ground scene beam is collected by the front telescope system 0501, folded by the first reflecting mirror 0107 and the second reflecting mirror 0108, and split into VNIR and SWIR bands by the beam splitter 0502. These bands then pass through corresponding incident microlens arrays 0503a and 0503b and enter corresponding fiber arrays 0110a and 0110b, respectively. The close-packed array 01101 receives the image from the front image plane 0109. The fiber image bundle 01102 rearranges the image and forms multiple images in the fiber optic slit groups 01103a and 01103b. A fiber optic slit 0202; the beam, after having its focal ratio corrected by corresponding microlens arrays 0504a and 0504b at the output end, enters corresponding beam splitting systems 0111a and 0111b. After being split by beam splitting system 0111, it forms the first spectral image plane 0204a and the second spectral image plane 0204b. Corresponding first time delay integration detector 0601 and second time delay integration detector 0602 receive the spectral signal at the corresponding spectral image plane, accumulate the signal electrons through time delay integration, and output high signal-to-noise ratio spectral image data.

[0079] Example 2:

[0080] like Figure 9 As shown, this invention provides a spaceborne hyperspectral imaging method based on time-delay integration. This method employs a spaceborne hyperspectral imaging system based on time-delay integration as described in Embodiment 1 above, and specifically includes:

[0081] S1. A beam of light from ground objects is collected by a front-view telescope system, and the beam is split into visible and near-infrared bands and short-wave infrared bands by a beam splitter, and then imaged onto the corresponding front-view image planes respectively.

[0082] S2. For each band, after passing through the incident end microlens array, the image of the corresponding front image plane is received by the fiber array, and the image is rearranged to form multiple fiber optic slits.

[0083] S3. The beam emitted from the multiple fiber optic slits is received by the microlens array at the output end, and the beam is split by using the multiple fiber optic slits as the entrance slits of the beam splitting system to form a spectral image plane.

[0084] S4. The spectral image plane is received by a time-delay integration detector, which has multiple photosensitive surface regions, each of which corresponds to a multiple fiber optic slits. The signal electrons are integrated and accumulated over time delay to output high signal-to-noise ratio spectral image data.

[0085] This embodiment presents a spaceborne hyperspectral imaging method based on time-delay integration, used in the spaceborne hyperspectral imaging system based on time-delay integration described in Embodiment 1. Specific implementation details can be found in the corresponding descriptions in Embodiment 1; to avoid redundancy, they will not be repeated here.

[0086] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A spaceborne hyperspectral imaging system based on time-delay integration, characterized in that, include: A front-view telescope system is used to collect a beam of light from ground objects and image the ground objects onto a front-view image plane; the front-view telescope system includes a beam splitter that splits the beam of light into a visible and near-infrared band and a short-wave infrared band. An incident end microlens array, including a first incident end microlens array and a second incident end microlens array, is used to improve the fiber array fill factor. The fiber array includes a first fiber array and a second fiber array, which respectively receive the images of the front image plane of the corresponding band through the first incident end microlens array and the second incident end microlens array, and rearrange the respective images to form multiple fiber optic slits. The output microlens array, including a first output microlens array and a second output microlens array, is used to correct the focal ratio of the fiber-exported beam. The beam splitting system includes a first beam splitting system and a second beam splitting system, which respectively receive beams emitted from corresponding multiple fiber optic slits through the first output end microlens array and the second output end microlens array, and split the beams to form a spectral image plane. The time-delay integration detector includes a first time-delay integration detector and a second time-delay integration detector, which are respectively disposed at the spectral image plane of the first beam splitting system and the second beam splitting system. Each of them has multiple photosensitive surface regions, which correspond to multiple fiber optic slits. They are used to accumulate signal electrons through time-delay integration and output high signal-to-noise ratio spectral image data.

2. The spaceborne hyperspectral imaging system based on time delay integration according to claim 1, characterized in that, The first fiber array and the second fiber array each include a close-packed array, a fiber image bundle, and a fiber slit group connected in sequence; the close-packed array is used to receive the image of the front image plane; The fiber optic image bundle is used to transmit the image received by the close-packed array to the fiber optic slit group and rearrange it; the fiber optic slit group consists of the multiple fiber optic slits formed by the rearrangement.

3. The spaceborne hyperspectral imaging system based on time delay integration according to claim 2, characterized in that, The optical fibers in the dense array are arranged in multiple columns in the track-crossing direction and in multiple rows in the track-following direction; the integration order of the corresponding time delay integration detector is equal to the number of rows in the track-following direction of the dense array.

4. A spaceborne hyperspectral imaging system based on time delay integration according to claim 3, characterized in that, Each column of the close-packed array is divided into multiple groups; in the fiber optic slit group, the columns of fibers in the same group are arranged at intervals, and the interval is not less than the width of the spectral image plane formed by a single column of fiber after passing through the beam splitting system in the dispersion direction. Fibers in columns of the same order in different groups are combined to form the same fiber optic slit.

5. A spaceborne hyperspectral imaging system based on time delay integration according to claim 4, characterized in that, The arrangement of each column of optical fibers in the same group within the optical fiber slit group corresponds to the same photosensitive surface region of the time delay integration detector; there is a physical interval between adjacent photosensitive surface regions of the time delay integration detector.

6. A spaceborne hyperspectral imaging system based on time-delay integration according to claim 1, characterized in that, The first incident microlens array and the second incident microlens array are square close-packed microlens arrays; the first exiting microlens array and the second exiting microlens array each include a first lens and a second lens. The first lens collimates the fiber-emitting beam into a parallel beam and images the fiber core onto the intermediate pupil plane. The second lens focuses the parallel beam onto the image-side focal plane. The fiber-emitting focal ratio is controlled by adjusting the focal length ratio of the first lens and the second lens.

7. A spaceborne hyperspectral imaging system based on time-delay integration according to claim 1, characterized in that, The first time-delay integral detector and the second time-delay integral detector are each composed of multiple detectors spliced ​​together, and each detector contains multiple photosensitive surface areas.

8. A spaceborne hyperspectral imaging system based on time delay integration according to claim 1, characterized in that, The spectral image planes formed by the first and second spectral systems each have long-wavelength spectral lines at one end and short-wavelength spectral lines at the other end in the dispersion direction.

9. A spaceborne hyperspectral imaging system based on time delay integration according to claim 1, characterized in that, The front image plane has an image plane movement direction along the track direction, the time delay integration detector has a charge accumulation direction, and the image plane movement direction is consistent with the charge accumulation direction.

10. A spaceborne hyperspectral imaging method based on time delay integration, characterized in that, include: S1. A beam of light from ground objects is collected by a front-view telescope system, and the beam is split into visible and near-infrared bands and short-wave infrared bands by a beam splitter, and then imaged onto the corresponding front-view image planes respectively. S2. For each band, after passing through the incident end microlens array, the image of the corresponding front image plane is received by the fiber array, and the image is rearranged to form multiple fiber optic slits. S3. The beam emitted from the multiple fiber optic slits is received by the microlens array at the output end, and the beam is split by using the multiple fiber optic slits as the entrance slits of the beam splitting system to form a spectral image plane. S4. The spectral image plane is received by a time-delay integration detector, which has multiple photosensitive surface regions, each of which corresponds to a multiple fiber optic slits. The signal electrons are integrated and accumulated over time delay to output high signal-to-noise ratio spectral image data.

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