Method for assembling and adjusting wide-spectrum wide-width hyperspectral camera system

Abstract

The invention discloses an installation and adjustment method for a wide-spectrum wide-width hyperspectral camera system, and the method comprises the steps: building a unified installation and adjustment reference of a high-precision reference prism and a special image plane reference tool, employing a modularized and criterion installation and adjustment process, and sequentially completing the wave aberration optimization installation and adjustment of a main optical telescope and the concentric shaft centering installation and adjustment of a spectrometer. And field separator butt joint, spectrograph butt joint and detector butt joint are completed according to strict quantitative criteria. A scientific installation and adjustment process of reference establishment, module installation and adjustment and assembly butt joint is adopted, a strict quantitative criterion is introduced, and the whole process is driven by objective data, so that the problems of non-uniform reference, difficulty in focal plane positioning, low multi-assembly collaborative installation and adjustment precision and poor efficiency in a traditional method are solved; high-precision, high-efficiency and high-consistency installation and adjustment of the wide-spectrum wide-width hyperspectral camera system are achieved, and powerful technical support is provided for the hyperspectral camera system to stably and efficiently obtain high-quality and high-precision hyperspectral image data.

Description

Technical Field

[0001] This invention belongs to the field of hyperspectral remote sensing technology, specifically relating to a method for assembling and adjusting a wide-spectrum, wide-swath hyperspectral camera system. Background Technology

[0002] Hyperspectral imaging technology is one of the core technologies in modern space-based Earth observation. It can simultaneously acquire geometric images of targets and continuous, detailed spectral data of ground features, enabling direct identification and classification of ground feature components. Currently, the main spectroscopic methods used in hyperspectral cameras include Fourier transform interference spectrometry, prism dispersion spectrometry, and grating dispersion spectrometry. Among these, grating dispersion spectrometry has gradually become the mainstream choice for high-performance hyperspectral cameras both domestically and internationally due to its advantages such as uniform spectral distribution, small spectral distortion and curvature, wide spectral range, high optical efficiency, and strong environmental adaptability.

[0003] Compared to multispectral cameras, which typically consist only of a telescope and a detector, hyperspectral cameras integrate multiple complex modules, including a main optical telescope, a field separator, a spectrometer, and a detector. They must maintain high-quality, high-precision hyperspectral imaging across a wide spectral range (e.g., 0.4–2.5 μm) and a wide swath width (e.g., >60 km). This places extremely high demands on the accuracy and stability of assembly and adjustment processes, such as optical axis alignment, focal plane coincidence, and attitude matching between modules. Furthermore, as Earth observation missions increasingly demand higher spectral and spatial resolution, the system architecture of hyperspectral cameras becomes increasingly complex, significantly increasing the difficulty of assembly and adjustment.

[0004] When applied to complex hyperspectral camera systems, traditional assembly and adjustment methods suffer from several problems: First, the lack of a unified, high-precision assembly and adjustment benchmark leads to inconsistent references between modules, making it difficult to quickly and accurately align the optical and mechanical axes, resulting in accumulated errors. Second, focal plane positioning relies on manual experience, making it difficult to accurately determine the focal plane position, resulting in low efficiency and poor repeatability, thus affecting image quality. Third, the lack of scientific assembly and adjustment procedures and effective quantitative criteria in multi-module collaborative assembly and adjustment, relying on subjective judgment, leads to long assembly and adjustment cycles and high costs. Fourth, the weak correlation between assembly and adjustment targets and final imaging performance indicators (such as MTF, spectral curvature, etc.) easily causes a disconnect between assembly and adjustment results and system performance. These problems severely restrict the development efficiency, assembly and adjustment consistency, and on-orbit reliability of wide-spectrum, wide-swath hyperspectral cameras, necessitating the development of a standardized, modular, and criteria-based high-precision assembly and adjustment method to support the rapid integration and high-quality delivery of high-performance hyperspectral cameras. Summary of the Invention

[0005] This invention proposes a method for assembling and adjusting a wide-spectrum, wide-swath hyperspectral camera system. Addressing issues such as inconsistent reference standards, low focal plane positioning accuracy, and a lack of scientific assembly and adjustment procedures and effective quantitative criteria for multi-component collaborative calibration in existing methods, this invention establishes a unified, high-precision assembly and adjustment reference based on a high-precision reference prism and dedicated image plane reference fixture. It proposes a scientific, modular, step-by-step assembly and adjustment strategy and introduces objective and effective quantitative criteria, effectively improving the assembly and adjustment accuracy and consistency of the hyperspectral camera. This provides effective technical support for the efficient development and reliable operation of wide-spectrum, wide-swath hyperspectral cameras.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for assembling and adjusting a wide-spectrum, wide-swath hyperspectral camera system, the hyperspectral camera system comprising a main optical telescope, a field separator, a spectrometer, and a detector, the method comprising the following steps:

[0008] Step 1: Establish a unified mounting and adjustment reference: Install the reference prism on the optical engine frame to establish an optical reference for the light rays from the infinity viewing axis; set the image plane reference fixture at the theoretical position of the primary focal plane of the main optical telescope to achieve rapid alignment of the optical axis and the mechanical axis. The image plane reference fixture is provided with a light-passing hole.

[0009] Step 2, Assembly and Adjustment of the Main Optical Telescope: Based on the reference prism and the image plane reference fixture, a self-collimating interference optical path is built, the aberrations of the center and edge fields of view of the main optical telescope are collected, and the poses of each mirror component of the main optical telescope are iteratively optimized to make the aberrations of the main optical telescope optimal across the entire field of view and to make the optical axes of each field of view of the main optical telescope coincide with the optical axes of the corresponding apertures of the image plane reference fixture.

[0010] Step 3, Spectrometer Assembly and Adjustment: Establish the optical axis reference of the spectrometer, center and adjust the spectrometer mirror and grating, construct the interference optical path, and iteratively optimize the position and pose of the spectrometer mirror and grating to achieve the best spectrometer imaging quality;

[0011] Step 4, Field Separator Docking: Adjust the field separator so that its slit azimuth angle is consistent with the designed track angle, and the pitch centering satisfies the condition that the absolute value deviation of the pitch angle is less than the threshold when the gray values ​​at both ends are close to zero, and the mid-plane of the slit structure coincides with the primary focal plane of the main optical telescope.

[0012] Step 5, Spectrometer docking: Adjust the spectrometer so that its object plane coincides with the primary focal plane of the main optical telescope, the slit coincides with the field of view of the corresponding layout of the main optical telescope, and the pitch is centered in the direction of the track crossing.

[0013] Step 6, Detector docking: Adjust the detector focal plane so that the modulation transfer function of the full field of view and the full spectrum is greater than the threshold, and adjust the detector rotation angle so that the center wavelength of different fields of view in the same spectral line is consistent and the spectral curvature is less than the threshold.

[0014] The present invention, by adopting the above technical solution, has the following beneficial effects:

[0015] 1. Adopting a modular scientific assembly and adjustment process of "benchmark establishment → module assembly and adjustment → component docking", the telescope, spectrometer, field separator and detector are independently assembled and adjusted and docked with high precision through a modular step-by-step assembly and adjustment strategy. This makes the assembly and adjustment process more scientific and efficient, effectively shortening the assembly and adjustment cycle by more than 30% compared with the traditional method, and effectively reducing the assembly and adjustment cost.

[0016] 2. A unified assembly and adjustment benchmark was established, transforming the abstract "optical focal plane" into a physical benchmark that can be physically reproduced and measured with high precision. This solved the problem of the focal plane being difficult to locate and reproduce in traditional assembly and adjustment, laying the foundation for high-precision assembly and adjustment of the entire system and effectively improving the consistency and repeatability of assembly and adjustment.

[0017] 3. An innovative method for establishing the optical axis reference of a spectrometer is proposed. The initial axis is determined by physically positioning the center of the lens sphere, which avoids the problem of inaccurate axis establishment in traditional assembly and adjustment. This provides a reliable reference for the subsequent precise assembly and adjustment of various optical components of the spectrometer, and greatly improves the accuracy and efficiency of spectrometer assembly and adjustment.

[0018] 4. By introducing strict quantitative criteria and using objective data-driven processes throughout the entire process, without relying on manual intervention, the assembly and adjustment process becomes more standardized and regulated. This avoids the drawbacks of relying on subjective judgment in traditional assembly and adjustment, ensuring that the camera system can maintain excellent optical performance under wide spectral and wide-swath conditions. The assembly and adjustment results have good repeatability and are suitable for standardized assembly and adjustment of multiple sets of products, which can significantly improve product consistency and reliability.

[0019] 5. The assembly and adjustment method described in this invention is highly operable and practical in real-world applications, and can be widely applied to various models and specifications of wide-spectrum hyperspectral camera systems, including spaceborne, airborne, and ground-based systems, thus possessing significant engineering application value. It provides strong technical support for hyperspectral camera systems to stably and efficiently acquire high-quality, high-precision hyperspectral image data. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the optical path of the broadband hyperspectral camera system used in a specific embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the field-of-view separator of the wide-spectrum hyperspectral camera system used in a specific embodiment of the present invention.

[0022] Figure 3 This is a schematic diagram of the assembly and adjustment method for a wide-spectrum, wide-swath hyperspectral camera system according to the present invention.

[0023] Figure 4This is a schematic diagram illustrating the establishment of a unified assembly and adjustment benchmark for a broadband hyperspectral camera system assembly and adjustment method according to the present invention.

[0024] Figure 5 This is a schematic diagram of the image plane reference fixture for the assembly and adjustment method of a wide-spectrum, wide-swath hyperspectral camera system according to the present invention.

[0025] Figure 6 This is a schematic diagram of the assembly and adjustment of the main optical telescope in a broadband hyperspectral camera system assembly and adjustment method according to the present invention.

[0026] Figure 7 This is a schematic diagram of the assembly and adjustment method for a wide-spectrum, wide-swath hyperspectral camera system according to the present invention.

[0027] Figure 8 This is a schematic diagram of the field-of-view separator docking method for a wide-spectrum, wide-swath hyperspectral camera system according to the present invention.

[0028] Figure 9 This is a schematic diagram showing the response of the detector assembly in the "vertical" and "horizontal" states of the assembly and adjustment method of a wide-spectrum hyperspectral camera system according to the present invention.

[0029] Figure 10 This is a schematic diagram of the performance test of a hyperspectral camera after assembly and adjustment based on the assembly and adjustment method of a wide-spectrum and wide-swath hyperspectral camera system according to the present invention.

[0030] The reference numerals in the attached figures are as follows:

[0031] 1-1 Primary lens, 1-2 Secondary lenses, and 1-3 Tertiary lenses;

[0032] 2 Field of view splitter: 2-1 Visible mirror group, 2-1-1 Visible mirror, 2-1-2 Visible slit; 2-2 Shortwave infrared mirror group, 2-2-1 Shortwave infrared primary mirror, 2-2-2 First shortwave infrared secondary mirror, 2-2-3 Second shortwave infrared secondary mirror, 2-2-4 First shortwave infrared slit, 2-2-5 Second shortwave infrared slit;

[0033] 30 Visible spectrometer frame, 3-1 Visible primary mirror, 3-2 Visible secondary mirror, 3-3 Visible correction lens, 3-4 Visible convex grating;

[0034] 4-1 Short-wave infrared primary reflector, 4-2 Short-wave infrared secondary reflector, 4-3 Short-wave infrared correction lens, 4-4 Short-wave infrared convex grating;

[0035] 5 Visible detector, 6 Shortwave infrared detector, 7-1 First plane conversion mirror, 7-2 Second plane conversion mirror, 7-3 Third plane conversion mirror, 11 Optomechanical frame, 15 Reference cubic prism assembly;

[0036] The markings for general-purpose assembly and adjustment equipment (T) and special-purpose tooling (G) are as follows:

[0037] T1 Theodolite; T2 Interferometer; T3 PI High-Precision Electric Displacement Stage; T4 Integrating Sphere; T5 Monochromator; T6 Electric Two-Dimensional Turntable; T7 Collimator; T8 Air-Floating Platform; T9 Ground Detection Equipment and Control System; T10 Cross Target; T11 Digital Microscope;

[0038] G1 Main optical image plane reference fixture: G1-1 base layer, G1-2 mounting and adjustment layer, G1-3 reference calibration layer, G1-4 light passage; G2 autocollimating plane mirror; G3 spectrometer image plane reference fixture; G4 spectrometer object plane reference fixture; G5 standard concave mirror. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above objectives, this invention adopts the following technical solution.

[0040] The technical solution of the present invention will be further described in detail below with reference to specific embodiments.

[0041] refer to Figure 1 This is a schematic diagram of the optical path of the wide-spectrum, wide-swath hyperspectral camera system used in this invention. The wide-spectrum, wide-swath hyperspectral camera has a spectral range covering 0.4-2.5 μm, a swath width of 60 km, a spatial resolution of 30 m, a visible light spectral resolution of 5 nm, and a short-wave infrared spectral resolution of 10 nm. The wide-spectrum, wide-swath hyperspectral camera system consists of a main optical telescope, a field-of-view splitter 2, a visible spectrometer, a short-wave infrared spectrometer, a visible detector 5, and a short-wave infrared detector 6. Light from the target is collected by the main optical telescope, then separated into visible light and short-wave infrared light by the field-of-view splitter 2 after passing through the first plane conversion mirror 7-1. The visible light is finely split by the visible spectrometer and then imaged on the visible detector 5 by the second plane conversion mirror 7-2. The short-wave infrared light is finely split by the short-wave infrared spectrometer after passing through the third plane conversion mirror 7-3 and then imaged on the short-wave infrared detector 6.

[0042] The specific parameters of the main optical telescope are 250mm aperture, 705mm focal length, F number 2.83, and field of view 4.86 degrees. It is an off-axis three-mirror structure, consisting of a primary mirror 1-1, a secondary mirror 1-2, and a third mirror 1-3. Light from the target passes through the primary mirror 1-1, the secondary mirror 1-2, and the third mirror 1-3 in sequence to collect the radiation energy of the ground object.

[0043] refer to Figure 2 This is a schematic diagram of the field-of-view separator of the wide-spectrum, wide-swath hyperspectral camera system used in this invention. The field-of-view separator 2 includes a visible mirror group 2-1 and a short-wave infrared mirror group 2-2. The visible mirror group 2-1 consists of a visible mirror 2-1-1 and a visible slit 2-1-2. The short-wave infrared mirror group 2-2 consists of a short-wave infrared primary mirror 2-2-1 and a first short-wave infrared secondary mirror 2-2-2 and a second short-wave infrared secondary mirror 2-2-3 located on both sides of the short-wave infrared primary mirror 2-2-1. The short-wave infrared primary mirror 2-2-1, the first short-wave infrared secondary mirror 2-2-2, and the second short-wave infrared secondary mirror 2-2-3 are connected together. Between the infrared secondary reflectors 2-2-3, there are also a first short-wave infrared slit 2-2-4 and a second short-wave infrared slit 2-2-5 respectively. A portion of the light rays from the main optical telescope are reflected by the visible reflector 2-1-1 and then enter the visible spectrometer through the visible slit 2-1-2. Another portion of the light rays are reflected by the short-wave infrared primary reflector 2-2-1 and split into two paths. After being reflected by the first short-wave infrared secondary reflector 2-2-2 and the second short-wave infrared secondary reflector 2-2-3 respectively, they enter the short-wave infrared spectrometer through the first short-wave infrared slit 2-2-4 and the second short-wave infrared slit 2-2-5 and then through the third plane deflector 7-3.

[0044] Both the visible spectrometer and the short-wave infrared spectrometer employ an improved Offner convex grating spectrometer with a correction lens. The visible spectrometer includes a primary visible mirror 3-1, a secondary visible mirror 3-2, a correction lens 3-3, and a convex visible grating 3-4. Light from the visible slit 2-1-2 of the field separator 2 is reflected sequentially by the correction lens 3-3 and the primary visible mirror 3-1 to the convex visible grating 3-4. After fine dispersion by the convex visible grating 3-4, the light passes through the secondary visible mirror 3-2 and the correction lens 3-3, and is then reflected by the second planar convoluted mirror 7-2 before entering the visible detector 5, achieving fine dispersion of the visible spectrum. The short-wave infrared spectrometer 4 includes a primary short-wave infrared mirror 4-1. 1. Short-wave infrared secondary reflector 4-2, short-wave infrared correction lens 4-3, and short-wave infrared convex grating 4-4; Light from the first short-wave infrared slit 2-2-4 and the second short-wave infrared slit 2-2-5 of the field separator 2 passes through the third planar deflector 7-3 and is reflected sequentially by the short-wave infrared correction lens 4-3 and the short-wave infrared primary reflector 4-1 to the short-wave infrared convex grating 4-4. After being finely split by the short-wave infrared convex grating 4-4, the light reaches the short-wave infrared secondary reflector 4-2, is reflected by the short-wave infrared correction lens 4-3, and then enters the short-wave infrared detector 6, thus achieving fine splitting of the short-wave infrared spectrum.

[0045] refer to Figure 3 The diagram below illustrates the assembly and adjustment method for a wide-spectrum, wide-swath hyperspectral camera system according to the present invention, and includes the following steps:

[0046] Step 1: Establish a unified assembly and adjustment reference: Install the reference cubic prism assembly on the optical engine frame to establish an optical reference for the light rays from the infinity viewing axis; set the main optical image plane reference fixture at the theoretical position of the primary focal plane of the main optical telescope to achieve rapid alignment of the optical axis and the mechanical axis. The main optical image plane reference fixture is provided with a light-passing hole.

[0047] Step 2, main optical telescope assembly and adjustment: Based on the reference cubic prism assembly and the main optical image plane reference fixture, a self-collimating interference optical path is built, the aberrations of the center and edge fields of view of the main optical telescope are collected, and the poses of each mirror assembly of the main telescope are iteratively optimized to make the aberrations of the main telescope in the entire field of view optimal and the optical axes of each field of view of the telescope coincide with the optical axes of the corresponding apertures of the main optical image plane reference fixture.

[0048] Step 3, spectrometer assembly and adjustment: Establish the optical axis reference of the spectrometer, center and adjust the spectrometer mirror and grating, construct the interference optical path, and iteratively optimize the position and pose of the spectrometer mirror and grating to achieve the best spectrometer imaging quality;

[0049] Step 4, Field Separator Docking: Adjust the field separator so that its slit azimuth angle is consistent with the designed track angle, the pitch centering satisfies the absolute value deviation of the pitch angle ≤ 5″ when the gray values ​​at both ends are close to zero, and the mid-plane of the slit structure coincides with the primary focal plane of the main optical telescope.

[0050] Step 5, Spectrometer docking: Adjust the spectrometer so that its object plane coincides with the primary focal plane of the main optical telescope, the slit coincides with the field of view of the corresponding layout of the main optical telescope, and the pitch is centered in the direction of the track crossing.

[0051] Step 6, detector docking: Adjust the detector focal plane to make the modulation transfer function of the full field of view and the full spectrum ≥0.25, and adjust the detector rotation angle to make the center wavelength of different fields of view in the same spectral line consistent and the spectral curvature ≤1nm.

[0052] The assembly and adjustment method described in this invention is used to assemble and adjust the above-mentioned wide-spectrum hyperspectral camera system, which mainly includes the following steps:

[0053] Step 1: Reference Figure 4 The diagram below illustrates the establishment of a unified assembly and adjustment benchmark for a broadband hyperspectral camera system assembly and adjustment method according to the present invention.

[0054] 1) Place the optical engine frame 11 on the air-floating platform T8, use the theodolite T1 to accurately measure and adjust the installation attitude of the reference cubic prism assembly 15. The cubic prism assembly 15 is installed on the mechanical axis of the optical engine frame 11, and the angle deviation between the optical axis of the cubic prism assembly 15 and the mechanical axis of the optical engine frame 11 is ≤10″, thereby establishing an accurate optical reference for the light rays from the infinity viewing axis.

[0055] 2) Using a coordinate measuring machine, the primary optical image plane reference fixture G1 is precisely installed at the theoretical position of the primary optical telescope's primary focal plane corresponding to the aperture position of the first plane conversion mirror 7-1; the positional accuracy of the reference plane of the primary optical image plane reference fixture G1 relative to the bottom surface of the optical-mechanical frame 11 is better than 0.02mm, and the parallelism is better than 0.01mm.

[0056] 3) The main optical image plane reference fixture G1 adopts a three-layer structure (from bottom to top: base layer G1-1, mounting layer G1-2, and reference calibration layer G1-3) to ensure repeatability and positioning accuracy. Using interferometer T2, by observing the interference fringes generated by its focal point on the surface of the reference calibration layer, the focal point of interferometer T2 can be positioned on the reference calibration layer G1-3 (on the primary focal plane), with a positioning accuracy ≤0.005mm; then move the focal point of interferometer T2 to the light-transmitting aperture with a diameter of 0.7mm.

[0057] Preferred, Reference Figure 5 This is a schematic diagram of the image plane reference fixture for the assembly and adjustment method of a wide-spectrum, wide-swath hyperspectral camera system according to the present invention. The base layer G1-1 is connected to the optical engine frame 11 and fixed to the optical engine frame 11 until it is removed when the main optical telescope is delivered. The assembly and adjustment layer G1-2 is precisely positioned on the base layer G1-1, and the reference calibration layer G1-3 is precisely positioned on the assembly and adjustment layer G1-2. The reference calibration layer G1-3 is used to simulate the primary focal plane of the main optical telescope, and the through-track and along-track field of view of the main optical telescope are determined through the 0.7mm diameter light-passing aperture G1-4. The assembly and adjustment layer G1-2 is used to adjust the reference calibration layer G1-3 to the primary focal plane of the main optical telescope.

[0058] This step establishes a unified assembly and adjustment benchmark and builds a high-precision spatial reference system, creatively transforming the abstract "focal plane" into a precisely reproducible physical position, providing a unique, stable, and reliable benchmark for all subsequent process operations involving the focal plane.

[0059] Step Two: Reference Figure 6 The diagram below illustrates the assembly and adjustment of the main optical telescope in a broadband hyperspectral camera system according to the present invention. The specific process is as follows:

[0060] 1) Use a coordinate measuring machine to initially install the primary mirror 1-1, secondary mirror 1-2, and tertiary mirror 1-3 components onto the optomechanical frame 11, with a positional accuracy ≤0.02mm;

[0061] 2) Based on the unified assembly and adjustment reference established in step 1, place the autocollimating plane mirror G2 in the optical path and align it with the cubic prism assembly 15. Use the interferometer T2 to collect the wavefront image of the central field of view of the main optical telescope through the light aperture (field of view limitation) of the main optical image plane reference fixture G1.

[0062] 3) Start the computer-aided assembly and adjustment software, analyze aberrations based on the acquired wavefront image, and use the iterative optimization algorithm of the optical system wavefront aberration sensitivity matrix to calculate the optimal compensation adjustment amount for primary mirror 1-1, secondary mirror 1-2, and tertiary mirror 1-3. The assembly and adjustment personnel make fine adjustments according to the instructions to achieve optimization of the central field of view.

[0063] 4) Sequentially switch the detection light of interferometer T2 to each light aperture of image plane reference fixture G1, repeat the above process of acquisition, analysis, calculation and adjustment, and optimize the edge field of view; after several iterations, make the aberration of the entire field of view reach the optimal, and make the optical axis of each field of view coincide with the optical axis of the corresponding light aperture.

[0064] This step elevates the traditional "mirror installation" to "system image quality optimization," directly targeting the final optical performance for reverse control, resulting in high precision and strong purposefulness.

[0065] Step 3: Reference Figure 7 The diagram below illustrates the assembly and adjustment of a grating spectrometer for a wide-spectrum, wide-swath hyperspectral camera system according to the present invention. The specific process is as follows:

[0066] 1. Setup and adjustment of the visible spectrometer:

[0067] 1) Fix the visible spectrometer frame 30 on the PI high-precision electric displacement stage T3, and use the spectrometer frame 30 as a reference to initially install the visible correction lens 3-3;

[0068] 2) Using interferometer T2, and through high-precision electric displacement stage T3, make its focal point in space precisely coincide with the convex center and concave center of the visible correction lens 3-3 in sequence; the two points determine a straight line, which is precisely defined as the optical axis reference of the visible spectrometer, and this optical axis reference coincides with the mechanical axis of the spectrometer frame;

[0069] 3) Using this optical axis as a reference, install and adjust the visible primary reflector 3-1 and the visible secondary reflector 3-2 to ensure that the relative position of their sphere center and the optical axis meets the design value;

[0070] 4) Install the visible convex grating 3-4, and adjust the thickness of its tie rod shim so that its sphere center is located on the optical axis and maintains the designed distance from the sphere center of the correction lens, thereby establishing the concentric axis relationship between the correction lens 3-3 and the convex grating 3-4;

[0071] 5) Install the spectrometer object plane reference fixture G4 at the spectrometer object plane to simulate the slit. Install the spectrometer image plane reference fixture G3 at the spectrometer image plane and place the standard concave mirror G5 to construct the return interference optical path of the Offner structure. Use the interferometer T2 to detect wavelet aberrations and then perform iterative fine-tuning again in combination with computer-aided assembly and adjustment software to optimize the poses of the visible primary mirror 3-1, the visible secondary mirror 3-2 and the convex grating 3-4 until the spectrometer module itself has the best imaging quality.

[0072] 2. Assembly and adjustment of shortwave spectrometer 4:

[0073] 1) Fix the shortwave spectrometer frame on the PI high-precision electric displacement stage T3, and initially install the shortwave infrared correction lens 4-3 with the shortwave spectrometer frame as the reference;

[0074] 2) Using interferometer T2, and through high-precision electric displacement stage T3, make its focal point in space precisely coincide with the convex center and concave center of the visible short-wave infrared correction lens 4-3 in sequence; the two points determine a straight line, which is precisely defined as the optical axis reference of the short-wave spectrometer, and this optical axis reference coincides with the mechanical axis of the spectrometer frame;

[0075] 3) Using this optical axis as a reference, install and adjust the short-wave infrared primary reflector 4-1 and the short-wave infrared secondary reflector 4-2 to ensure that the relative position of their sphere center and the optical axis meets the design value.

[0076] 4) Install the short-wave infrared convex grating 4-4, and adjust the thickness of its pull rod shim so that its sphere center is located on the optical axis and maintains the designed distance from the sphere center of the correction lens, thereby establishing the concentric axis relationship between the short-wave infrared correction lens 4-3 and the short-wave infrared convex grating 4-4.

[0077] 5) Install the spectrometer object plane reference fixture G4 at the object plane of the spectrometer to simulate the slit. Install the spectrometer image plane reference fixture G3 at the image plane and place the standard concave mirror G5 to construct the return interference optical path of the Offner structure. Use the interferometer T2 to detect wavelet aberrations and then perform iterative fine-tuning again in combination with computer-aided assembly and adjustment software to optimize the pose of the short-wave infrared primary reflector 4-1, the short-wave infrared secondary reflector 4-2 and the short-wave infrared convex grating 4-4 ​​until the spectrometer module itself has the best imaging quality.

[0078] In this step, the spectrometer setup is based on concentric axis centering with the lens centers coinciding. The initial axis is determined by physically positioning the lens center, thus avoiding the problem of inaccurate axis establishment in traditional setups.

[0079] Step Four: Reference Figure 8This diagram illustrates the field-view separator docking method for a wide-spectrum, wide-swath hyperspectral camera system according to the present invention. The docking of the field-view separator 2 is based on a precise three-criteria system. The assembled and adjusted main optical telescope is placed on an electric two-dimensional turntable T6, and the system is zeroed using a collimator T7 and a theodolite T1. Only when all three quantitative criteria—azimuth consistency, pitch centering, and focal plane coincidence—are simultaneously met is the field-view separator docking considered complete, ensuring minimal astigmatism and defocus introduced. The specific process is as follows:

[0080] 1) Azimuth Consistency Adjustment: Initially install the field separator 2; illuminate the crosshair target T10 installed at the focal plane of the collimator T7 using the integrating sphere T4; after passing through the collimator T7 and the main optical telescope system, the image of the crosshair target is located at the primary focal plane of the main optical telescope; rotate the azimuth angle of the motorized two-dimensional turntable T6, and observe the image of the crosshair target T10 on the slit through the digital microscope T11 placed at the primary focal plane. The slit is located at the object plane of the spectrometer and fixed on the main optical engine frame. Adjust the azimuth of the field separator 2 so that its slit along the track direction is precisely aligned with the track angle required by the design of the main optical telescope; so that the visible spectrometer is accurately positioned in the layout field of view of the main optical telescope.

[0081] 2) Pitch centering adjustment: Rotate the electric two-dimensional turntable T6 to adjust the pitch angle and observe the clarity of the target images at both ends of the slit through-track direction; adjust the position of the field separator 2 in the through-track direction so that the target images at both ends are clear at the same time, and record the pitch angle when the target images at both ends just disappear (grayscale value is zero), and ensure that the absolute value deviation between the two is ≤5″.

[0082] 3) Focal plane coincidence adjustment: Combine the focusing and displacement stage readings of the digital microscope T11 to finely adjust the position of the field separator 2 along the optical axis so that its structural mid-surface precisely coincides with the primary focal plane of the main optical telescope.

[0083] Step 5: The spectrometer docking is based on the criterion that the slit surface coincides with the primary focal plane of the main optical telescope. This ensures that the absolute values ​​of the pitch angles at the upper and lower edge fields of view are approximately equal when the gray values ​​approach zero, thus achieving pitch centering in the track crossing direction. The specific process is as follows:

[0084] 1. Docking the visible spectrometer with the main optical telescope:

[0085] 1) Install the visible spectrometer on the PI high-precision electric displacement stage T3 using a tooling fixture, and dock it with the main optical telescope.

[0086] 2) Use the collimator T7 to generate a crosshair target image, and observe the dispersive image received by the visible detector 5 through the ground detection equipment and control system T9.

[0087] 3) Slit Surface Coincidence Criterion: By fine-tuning the visible spectrometer's position along the optical axis (Z-axis) using the PI high-precision electric displacement stage T3, observe the peak gray value of the dispersive image in the ground detection equipment and control system T9. Adjust to the maximum gray value; at this point, the slit surface of the spectrometer is determined to coincide with the primary focal plane of the main optical telescope. Fine-tune the visible spectrometer along the spectral dimension and observe the width of the dispersive image. Adjust to the widest dispersive width; at this point, the slit of the spectrometer is determined to coincide with the corresponding layout field of view of the main optical telescope. Simultaneously, adjust the pitch / roll of the visible spectrometer to achieve pitch centering in the track crossing direction (gray value vanishing angle deviation at both ends ≤ 5″).

[0088] 2. Docking between the shortwave infrared spectrometer and the main optical telescope:

[0089] Repeat step 1 to complete the docking of the shortwave infrared spectrometer with the main optical telescope.

[0090] Step Six: Reference Figure 9 This diagram illustrates the response of a wide-spectrum, wide-swath hyperspectral camera system assembly and adjustment method in both "vertical" and "horizontal" states on the detector assembly. The detector docking requires dual-objective optimization of both "vertical" and "horizontal" states. The final assembly and adjustment objective is directly locked onto the camera's spectral and imaging core performance indicators, ensuring the optimality of the assembly and adjustment results. The specific process is as follows:

[0091] 1. The visible detector 5 is docked with the visible spectrometer:

[0092] 1) Initial adjustment of spectral response range: Using monochromator T5 to output monochromatic light of different wavelengths, the visible detector 5 was translated and rotated to confirm that its response covers the full spectrum of 0.4-2.5μm;

[0093] 2) "Vertical State" Optimization (MTF Maximization): Install a multi-slit target on the focal plane of the collimator and illuminate it with an integrating sphere T4; finely adjust the position (along the optical axis) and angle of the focal plane of the visible detector 5 using a PI high-precision electric displacement stage T3, while monitoring the modulation transfer function (MTF) of the entire field of view and the entire spectrum using MTF measurement software; the adjustment goal is to make the MTF value of all fields of view and all spectrums ≥ 0.25, this state is called "vertical state".

[0094] 3) "Horizontal flat state" optimization (spectral curvature minimization): Use monochromator T5 to illuminate the ground detection equipment and control system T9, and read the pixel number corresponding to the same spectral line (same wavelength) at different track crossing field positions; use PI high-precision electric displacement stage T3 to finely rotate the detector so that the light of the same wavelength falls on the same spectral dimension at different track crossing positions, that is, the center wavelength remains consistent, ensuring that the calculated spectral curvature is ≤1nm. This state is called "horizontal flat state".

[0095] 4) Iterative optimization: Since there may be slight coupling between adjusting MTF (vertical state) and adjusting spectral curvature (horizontal state), several iterations of fine-tuning are required until both reach the optimal criterion requirements simultaneously.

[0096] 2. Interconnection between shortwave infrared detector 6 and shortwave infrared spectrometer:

[0097] Repeat step 1 to complete the docking of the shortwave infrared detector 6 with the shortwave infrared spectrometer.

[0098] System performance testing and verification

[0099] refer to Figure 10 This diagram illustrates the performance testing of a hyperspectral camera after assembly and adjustment, based on the method for assembling and adjusting a wide-spectrum, wide-swath hyperspectral camera system according to the present invention. The hyperspectral camera is placed on an electrically driven two-dimensional turntable T6. Performance tests are conducted at different fields of view by rotating the turntable. A collimator is used to simulate ground targets at infinity. The light source at the focal plane of the collimator is used to switch between monochromatic and polychromatic light sources. Ground-based detection equipment and control system T9 are used for remote telemetry, remote control, and remote sensing data acquisition. Comprehensive performance tests are performed on the assembled hyperspectral camera, including: testing the spectral range and resolution using a monochromator T5; testing the MTF (≥0.25) across the entire field of view and spectrum using a multi-slit target and integrating sphere T4 light source; analyzing spectral images to test spectral distortion (≤0.2 pixels) and spectral curvature (≤1 nm); and testing radiometric performance such as signal-to-noise ratio (SNR) and dynamic range (DR) using integrating sphere light sources with different radiance levels. Finally, all technical indicators are confirmed to meet the design requirements. The results of this embodiment are shown in Table 1. All indicators meet or significantly exceed the design requirements, proving the effectiveness and superiority of the assembly and adjustment method of the present invention.

[0100] Table 1 Performance indicators and test results of the wide-spectrum hyperspectral camera

[0101]

[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for assembling and adjusting a wide-spectrum, wide-swath hyperspectral camera system, the hyperspectral camera system comprising a main optical telescope, a field separator, a spectrometer, and a detector, characterized in that, The method includes the following steps: Step 1: Establish a unified mounting and adjustment reference: Install the reference prism on the optical engine frame to establish an optical reference for the light rays from the infinity viewing axis; set the image plane reference fixture at the theoretical position of the primary focal plane of the main optical telescope to achieve rapid alignment of the optical axis and the mechanical axis. The image plane reference fixture is provided with a light-passing hole. Step 2, Assembly and Adjustment of the Main Optical Telescope: Based on the reference prism and the image plane reference fixture, a self-collimating interference optical path is built, the aberrations of the center and edge fields of view of the main optical telescope are collected, and the poses of each mirror component of the main optical telescope are iteratively optimized to make the aberrations of the main optical telescope optimal across the entire field of view and to make the optical axes of each field of view of the main optical telescope coincide with the optical axes of the corresponding apertures of the image plane reference fixture. Step 3, Spectrometer Assembly and Adjustment: Establish the optical axis reference of the spectrometer, center and adjust the spectrometer mirror and grating, construct the interference optical path, and iteratively optimize the pose of the spectrometer mirror and grating to achieve the best spectrometer imaging quality; Step 4, Field Separator Docking: Adjust the field separator so that its slit azimuth angle is consistent with the designed track angle, and the pitch centering satisfies the condition that the absolute value deviation of the pitch angle is less than the threshold when the gray values ​​at both ends are close to zero, and the mid-plane of the slit structure coincides with the primary focal plane of the main optical telescope. Step 5, Spectrometer docking: Adjust the spectrometer so that its object plane coincides with the primary focal plane of the main optical telescope, the slit coincides with the field of view of the corresponding layout of the main optical telescope, and the pitch is centered in the direction of the track crossing. Step 6, Detector docking: Adjust the detector focal plane so that the modulation transfer function of the full field of view and the full spectrum is greater than the threshold, and adjust the detector rotation angle so that the center wavelength of different fields of view in the same spectral line is consistent and the spectral curvature is less than the threshold.

2. The assembly and adjustment method for a broadband hyperspectral camera system according to claim 1, characterized in that, The included angle deviation between the reference prism and the mechanical axis of the optical engine frame is ≤10″; the image plane reference fixture adopts a multi-layer positioning structure, including a base layer, an adjustment layer and a reference calibration layer, and the reference calibration layer is provided with a light-transmitting hole with a diameter of ≤0.7mm; the focal plane positioning accuracy of the image plane reference fixture is ≤0.005mm.

3. The assembly and adjustment method for a broadband hyperspectral camera system according to claim 1, characterized in that, The pose optimization of each mirror component of the main optical telescope is based on the iterative optimization algorithm of the wave aberration sensitivity matrix of computer-aided software. The central field of view and the edge field of view of the main optical telescope are adjusted sequentially until the wave aberration of the entire field of view meets the design requirements.

4. The assembly and adjustment method for a broadband hyperspectral camera system according to claim 1, characterized in that, The process of establishing the optical axis reference of the spectrometer is as follows: Using the spectrometer frame as a reference, install a calibration lens and make the interferometer focal point coincide with the center of the convex and concave surfaces of the calibration lens in sequence to determine a straight line, which is the optical axis reference of the spectrometer.

5. The assembly and adjustment method for a broadband hyperspectral camera system according to claim 1, characterized in that, The method for centering and adjusting the spectrometer reflector and grating includes: installing and adjusting the relative position of the center of the spectrometer reflector and the optical axis reference of the spectrometer to meet the design value; then installing and adjusting the center of the grating to be on the optical axis reference of the spectrometer and maintaining a certain design distance from the center of the correction lens to establish the concentric axis relationship between the correction lens and the grating.

6. The assembly and adjustment method of a broadband hyperspectral camera system according to claim 1, characterized in that, The method for iterative optimization of the spectrometer mirror and grating pose includes: installing an object plane reference fixture at the object plane of the spectrometer, installing an image plane reference fixture at the image plane and placing a standard concave mirror to construct a return interference optical path; using an interferometer to detect wavelet aberration, and performing iterative fine-tuning based on the iterative optimization algorithm of the wavelet aberration sensitivity matrix of computer-aided software to optimize the pose of the mirror and grating, so as to achieve the best imaging quality of the spectrometer.

7. The assembly and adjustment method for a broadband hyperspectral camera system according to claim 1, characterized in that, The process of assembling and adjusting the spectrometer is as follows: By fine-tuning the spectrometer, observe the dispersion width and gray value of the crosshair target image. When the gray value reaches its maximum, the object plane of the spectrometer slit coincides with the primary focal plane of the main optical telescope. When the dispersion width reaches its maximum, the slit coincides with the corresponding layout field of view of the main optical telescope. When the gray value at the edge of the field of view at both ends of the track crossing direction approaches zero, the pitch is centered in the track crossing direction.

8. The assembly and adjustment method of a broadband hyperspectral camera system according to claim 1, characterized in that, The detector docking and adjustment process is as follows: Monochromator outputs monochromatic light on the focal plane of collimator to confirm that the detector's spectral response range meets the design requirements. Then, multi-slit target and integrating sphere light source are installed on the focal plane of collimator. The modulation transfer function of the detector in the full field of view and full spectrum is observed using MTF measurement software. Fine-tune the detector's focal plane position and angle to achieve the optimal MTF across the entire field of view and spectrum, with the MTF exceeding the threshold. After completion, remove the multi-slit target and integrating sphere light source, and reuse the monochromator as the light source. Finely rotate the detector to ensure that the center wavelengths of different cross-track fields of view on the same spectral line remain consistent to achieve the optimal state, with spectral curvature less than the threshold. Repeat the above iterative optimization steps.

9. The assembly and adjustment method of a broadband hyperspectral camera system according to claim 1, characterized in that, In step 4, the absolute value deviation of the pitch angle is set to ≤5″.

10. The assembly and adjustment method of a broadband hyperspectral camera system according to claim 1, characterized in that, In step 6, the full-field-of-view full-spectrum modulation transfer function is set to ≥0.25; the spectral curvature is set to ≤1nm.

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