A method for stitching together focal plane components of a spatial array hyperspectral camera

Abstract

This invention discloses a method for stitching together the focal plane components of a space-based hyperspectral camera, belonging to the field of space remote sensing technology, and aims to solve the problems existing in the prior art. The stitching method of this invention utilizes a stitching device consisting of a three-dimensional precision adjustment frame and a stitching instrument, as well as stitching fixtures and positioning fixture aluminum blocks for stitching. Simultaneously, alignment and positioning are performed using a theodolite. The reference cubic mirror assembly, dichroic mirror assembly, first beam-splitting reflector assembly, second beam-splitting reflector assembly, first spectral detector assembly, second spectral detector assembly, third spectral detector assembly, and fourth spectral detector assembly are sequentially mounted on the focal plane support.

Description

Technical Field

[0001] This invention belongs to the field of space remote sensing technology, specifically relating to a method for stitching together focal plane components of a space array hyperspectral camera. Background Technology

[0002] Miniaturization of satellites and space cameras is a significant trend in the field of space remote sensing, and a crucial prerequisite for achieving multi-satellite launch technology, saving development and launch costs, and shortening the development cycle. However, miniaturization and the observation efficiency of space cameras are somewhat contradictory. The limitations of aperture and field of view severely restrict the installation and arrangement of the numerous functional units of small space cameras.

[0003] Hyperspectral remote sensing offers significant advantages in the detailed classification and identification of ground features, and has become an important technology for space-based reconnaissance. It plays a crucial role in the identification and analysis of camouflaged and decoy targets on land and at sea. Due to spectral band setup and detector matching issues, beam splitting is typically required to ensure sufficient installation space for all detectors. Generally, there are two methods: field-of-view beam splitting and back-working-distance beam splitting. Field-of-view beam splitting uses mirrors to divide a broad-spectrum beam into different imaging regions, allowing different spectral bands to be incident on their respective detectors. This method requires the optical system to have a sufficient field of view in the splitting direction to avoid obstruction of the imaging beam. Back-working-distance beam splitting uses one (or more) dichroic mirrors in the back working distance of the main optical system to achieve beam splitting of two broad-spectrum bands by reflecting spectral band 1 and transmitting spectral band 2. When a single-segment array detector cannot meet the limited field of view, it is necessary to combine the two spectral dispersive methods, resulting in a compact and complex spectral focal plane. Based on the spectral band registration requirements, the positional alignment accuracy of each spectral band detector is required to be better than 2μm, and the coplanarity is required to be better than 5μm, which places extremely high demands on detector splicing. Since multiple spectral dispersive methods require sufficient working distance, the front working distance of a high-resolution tool microscope is difficult to meet the operational requirements, resulting in interference between the microscope head and the focal plane assembly when the microscope head moves. Summary of the Invention

[0004] The purpose of this invention is to propose a splicing method for the focal plane assembly of a spatial array hyperspectral camera with limited space volume, highly folded optical paths, integration, and multiple detectors, thereby solving the problems existing in the prior art.

[0005] To achieve the above objectives, a method for stitching together a focal plane assembly of a spatial array hyperspectral camera according to the present invention includes the following steps:

[0006] Step 1: Fix the focal plane support to the air-float platform using a double-sided parallel aluminum tooling block, so that the detector mounting surface of the focal plane support is horizontal.

[0007] Step 2: Install the reference cubic mirror assembly as a whole on the corresponding position of the focal plane support, so that the coordinate system formed by the three vertical planes of the cubic mirror in the reference cubic mirror assembly is parallel to the mechanical coordinate system of the focal plane support, with an error not exceeding 3″.

[0008] Step 3: Install the dichroic mirror assembly on the corresponding position of the focal plane support, aim at its dichroic surface with a theodolite, and use the coordinate system formed by the reference cubic mirror as a reference to adjust the dichroic mirror adjustment pad of the dichroic mirror assembly so that the two-dimensional spatial angle of the dichroic surface of the dichroic mirror assembly in the coordinate system formed by the reference cubic mirror of the reference cubic mirror assembly has an error of no more than 3″ compared with the design value.

[0009] Step 4: Adjust the optical axis angle of the theodolite mentioned in Step 3 so that the incident angle deviation of the light emitted by the theodolite and the hyperspectral camera does not exceed 5″.

[0010] Step 5: Install the first beam-splitting mirror assembly in the corresponding position on the focal plane support;

[0011] Step 6: Place a plane mirror at the detector interface plane corresponding to the first beam splitter of the first beam splitter assembly. The reflecting surface of the plane mirror is in contact with the detector interface plane. Repair the base of the first beam splitter assembly so that the crosshair returned by the theodolite through the plane mirror in Step 4 coincides with the reference crosshair, with a bidirectional error of no more than 2″.

[0012] Step 7: Repeat steps 5 and 6 to install the second beam-splitting mirror assembly;

[0013] Step 8: Connect the focal plane support to the three-dimensional precision adjustment frame using a splicing fixture, and fix it under the lens of the splicer, so that the splicer can observe the complete target surface of the detector without spatial interference with the focal plane support;

[0014] Step 9: Install the first spectral detector assembly. Select the four corner pixels of the photosensitive surface of the array detector of the first spectral detector assembly as the stitching aiming objects. Define the coordinates of the four pixels as (0,0), (0,1), (1,0) and (1,1). Using pixel (0,0) as the reference, measure the relative defocus of the other three pixels using the defocus method. Adjust the detector adjustment pad of the first spectral detector assembly so that pixel (1,0) is coplanar with pixel (0,0) with an error not exceeding 0.003mm, pixel (1,1) is coplanar with pixel (0,1) with an error not exceeding 0.003mm, and the relative defocus of pixel (0,1) and pixel (0,0) and the relative defocus of pixel (1,1) and pixel (1,0) do not exceed 0.003mm.

[0015] Step 10: Repeat Step 9 to install the second, third, and fourth spectral detector components. The repair and measurement of the second, third, and fourth spectral detector components are based on the four corner pixels of the first spectral detector component.

[0016] Step 11: Adjust the positions of the second, third, and fourth spectral detector components installed in Step 10, so that the first and second spectral detector components are spliced ​​together to form the first target surface according to the specified number of overlapping pixels; the third and fourth spectral detector components are spliced ​​together to form the second target surface according to the specified number of overlapping pixels; the bidirectional positional deviation between the first and second target surfaces does not exceed 0.002mm, and the detector splicing is completed.

[0017] The installation process of the reference cubic mirror assembly described in step two is as follows: auxiliary measurement is performed using two theodolites with orthogonal optical axes, and the error accuracy is ensured by sizing the base of the reference cubic mirror assembly.

[0018] When installing the first beam splitter assembly as described in step five, install the first beam splitter and its positioning fixture aluminum block. The position of the beam splitter of the first beam splitter assembly is ensured by the abutting surface of the positioning fixture aluminum block.

[0019] The positioning fixture aluminum block includes two parallel mounting surfaces and a backing surface. The backing surface is centered relative to the mounting surface, and the mounting surfaces have mounting holes perpendicular to the mounting surfaces at both ends.

[0020] The splicing fixture described in step eight includes a fixture mounting base and a fixed frame that is vertically fixed on the upper surface of the mounting base; one side of the fixed frame is a reference vertical plane 1303, the other side is an inclined plane, and the upper surface is a reference horizontal plane; the bottom surface of the focal plane bracket is fixedly connected to the inclined plane of the splicing fixture.

[0021] The adjustment process of the focal plane support on the three-dimensional precision adjustment frame described in step eight is as follows: the focal plane support is adjusted using the three-dimensional precision adjustment frame so that the coordinate system of the reference cubic mirror is parallel to the coordinate system of the stitching instrument, with an error not exceeding 5″. Then, the focal plane support is rotated by an angle θ along the long axis of the stitching instrument using a theodolite for auxiliary measurement, while the other two dimensions remain unchanged, so that the stitching instrument can observe the complete target surface of the detector and does not interfere with the space of the focal plane support.

[0022] The relative defocus amount Δh mentioned in step nine is determined by the following formula:

[0023] Δh=n×a×tanθ

[0024] In the formula: n is the number of pixel columns of the spectral detector;

[0025] a is the pixel size of the spectral detector;

[0026] θ is the rotation angle described in step eight.

[0027] The beneficial effects of this invention are as follows: The splicing method of the focal plane assembly of a spatial array hyperspectral camera of this invention applies spatial intersection measurement and autocollimation optical measurement methods to the precise positioning of the focal plane assembly, solving the splicing problem of the focal plane assembly of a compact multi-detector spatial array hyperspectral camera; the tilt reference method is adopted, which solves the problem of insufficient working distance in front of the high-resolution tool microscope during splicing, and is particularly suitable for complex focal plane assemblies with limited space volume, long optical paths and multiple folds, and has the characteristics of simple principle and high precision. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the optical path of a focal plane component for a spatial array hyperspectral camera.

[0029] Figure 2 This is a schematic diagram of the focal plane assembly structure of a spatial array hyperspectral camera.

[0030] Figure 3 Top view of a focal plane assembly structure for a spatial array hyperspectral camera without the dust cover;

[0031] Figure 4 Left view of a focal plane assembly structure for a spatial array hyperspectral camera without the aperture stop;

[0032] Figure 5 A schematic diagram showing one side of the focal plane support in a focal plane assembly of a spatial array hyperspectral camera;

[0033] Figure 6 This is a schematic diagram showing another side of the focal plane support in a spatial array hyperspectral camera focal plane assembly.

[0034] Figure 7 A bottom view of the focal plane support in a focal plane assembly of a spatial array hyperspectral camera.

[0035] Figure 8 This is a schematic diagram of the dichroic mirror assembly in the focal plane component of a spatial array hyperspectral camera.

[0036] Figure 9 This is a schematic diagram of the beam-splitting mirror assembly in the focal plane assembly of a spatial array hyperspectral camera.

[0037] Figure 10 This is a side view of the spectral detector component in the focal plane assembly of a spatial array hyperspectral camera.

[0038] Figure 11This is a schematic diagram of the other side of the spectral detector component in the focal plane assembly of a spatial array hyperspectral camera.

[0039] Figure 12 This is a schematic diagram of the detector adjustment pad structure in the focal plane assembly of a spatial array hyperspectral camera.

[0040] Figure 13 This is a schematic diagram illustrating the principle of measuring the installation angle of the dichroic mirror in a splicing method for the focal plane assembly of a spatial array hyperspectral camera according to the present invention.

[0041] Figure 14 This is a schematic diagram illustrating the principle of measuring the installation angle of the beam-splitting mirror in a splicing method for the focal plane assembly of a spatial array hyperspectral camera according to the present invention.

[0042] Figure 15 This is a schematic diagram of the positioning tooling aluminum block structure in the splicing method of the focal plane assembly of a spatial array hyperspectral camera according to the present invention.

[0043] Figure 16 This is a schematic diagram of the splicing fixture structure in a splicing method for a spatial array hyperspectral camera focal plane assembly according to the present invention.

[0044] Figure 17 This is a schematic diagram of the splicing equipment in a splicing method for a spatial array hyperspectral camera focal plane assembly according to the present invention;

[0045] Figure 18 This is a schematic diagram of the spectral detector splicing principle in a splicing method for a spatial array hyperspectral camera focal plane assembly according to the present invention.

[0046] The components include: 1. Focal plane support, 101. First reference plane, 102. First parallel plane, 103. Second reference plane, 104. Component mounting surface, 105. Glue injection hole, 106. Pre-fabricated pin hole; 2. Dichroic mirror assembly, 201. Dichroic mirror, 202. Dichroic mirror frame, 203. Thin flexible structure, 204. Dichroic mirror adjustment pad; 3. First beam splitter mirror assembly, 301. First beam splitter mirror, 302. Base, 303. Flexible structure; 4. Second beam splitter mirror assembly, 401. Second beam splitter mirror; 5. First spectral detector assembly, 501. Area array detector, 502. Detector frame, 503. Bandpass filter, 504. Detector adjustment pad, 505. Detector cover; 506. First spectral image plane; 6. Second spectral detector assembly, 601. Second spectral image plane; 7. Third spectral detector group. Components: 701, Third Spectral Image Plane; 8, Fourth Spectral Detector Assembly; 801, Fourth Spectral Image Plane; 9, Dust Cover; 10, Aperture; 11, Reference Cubic Mirror Assembly; 12, Positioning Fixture Aluminum Block; 1201, Mounting Surface; 1202, Abutment Surface; 1203, Mounting Hole; 13, Splicing Fixture; 1301, Fixture Mounting Base; 1302, Fixing Frame; 1303, Reference Vertical Plane; 1304, Inclined Surface. 1305. Reference horizontal plane; 14. Reference crosshairs; 15. Return image; 16. Plane mirror; 17. Three-dimensional precision adjustment frame; 18. Stitching device; 1801. Stitching device lens; 19. First theodolite; 1901. Mutual alignment optical axis of the first theodolite; 1902. Autocollimation optical axis of the first theodolite; 20. Second theodolite; 2001. Mutual alignment optical axis of the second theodolite; 2002. Autocollimation optical axis of the second theodolite. Detailed Implementation

[0047] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0048] See Figures 1-7 The focal plane assembly of a spatial array hyperspectral camera according to the present invention includes:

[0049] A focal plane support 1 is provided with a first reference surface 101, a first parallel surface 102, a second reference surface 103, a component mounting surface 104, four glue injection holes 105 (4 locations), and two pre-fabricated pin holes 106 (2 locations). The first parallel surface 102 is symmetrical to the first reference surface 101, with a coplanarity better than 0.003 mm and a parallelism better than 0.005 mm. The second reference surface 103 is perpendicular to the first reference surface 101 to a degree better than 0.005 mm. The component mounting surface 104 is perpendicular to the first reference surface 101 to a degree better than 0.01 mm.

[0050] The dichroic mirror assembly 2 is positioned and installed on the internal component mounting surface 104 of the focal plane support 1 through the pre-made pin holes 106; the dichroic mirror 201 of the dichroic mirror assembly 2 is coated with a dichroic film and an anti-reflection film on both sides respectively, with a reflection band of 450nm~600nm and a transmission band of 600nm~860nm.

[0051] The first beam splitter assembly 3 and the second beam splitter assembly 4 are installed inside the focal plane support 1 and positioned by injection through the injection hole 105. The first beam splitter assembly 3 and the second beam splitter assembly 4 receive the reflected light and transmitted light of the dichroic mirror assembly 2, respectively.

[0052] Four sets of identical spectral detector assemblies are installed on the first reference plane 101 and the first parallel plane 102, namely the first spectral detector assembly 5, the second spectral detector assembly 6, the third spectral detector assembly 7 and the fourth spectral detector assembly 8. The first spectral detector assembly 5 and the second spectral detector assembly 6 are symmetrical with respect to the first beam-splitting mirror assembly 3, and the third spectral detector assembly 7 and the fourth spectral detector assembly 8 are symmetrical with respect to the second beam-splitting mirror assembly 4.

[0053] An aperture 10 is set at the light inlet of the focal plane support 1;

[0054] And a dust cover 9 is provided on the upper end of the focal plane support 1;

[0055] The incident light rays pass through the aperture and illuminate the dichroic mirror 201 of the dichroic mirror assembly 2. The light rays reflected by the dichroic mirror 201 illuminate the first beam-splitting mirror assembly 3. After being split by the first beam-splitting mirror assembly 3, the light rays illuminate the area array detectors 501 of the corresponding two sets of spectral detector assemblies, namely the first spectral image plane 506 of the first spectral detector assembly 5 and the second spectral image plane 601 of the second spectral detector assembly 6. The light rays transmitted through the dichroic mirror 201 illuminate the second beam-splitting mirror assembly 4. After being split by the second beam-splitting mirror assembly 4, the light rays illuminate the area array detectors 501 of the corresponding two sets of spectral detector assemblies, namely the third spectral image plane 701 of the third spectral detector assembly 7 and the fourth spectral image plane 801 of the fourth spectral detector assembly 8.

[0056] The first reference surface 101 of the focal plane support 1 is composed of four rectangular bosses coplanarly, with a coplanarity better than 0.003 mm; the second reference surface 103 has a flatness better than 0.003 mm, and the component mounting surface 104 has a flatness better than 0.003 mm.

[0057] The injection hole 105 has a diameter of Φ2.5mm. Optical epoxy adhesive is injected through the injection hole 105 into the mounting interface corresponding to the first beam splitter assembly 3 and the second beam splitter assembly 4 with the focal plane support 1 for bonding, curing, and positioning. The pre-made pin hole 106 has a diameter of Φ2.8mm. The pin is connected and positioned to the dichroic mirror assembly 2 through the pre-made pin hole 106 on the focal plane support 1. The reason for using the two positioning methods for the first beam splitter assembly 3, the second beam splitter assembly 4, and the dichroic mirror assembly 2 is that drilling pins will cause a slight loss of positioning accuracy. To ensure that the final splicing accuracy of the detector is exactly what is seen under the splicer, using optical epoxy adhesive is the most reliable method.

[0058] See Figure 8 The dichroic mirror assembly 2 includes a dichroic mirror 201, a dichroic mirror frame 202, a thin-film flexible structure 203, and a dichroic mirror adjustment pad 204. The dichroic mirror 201 and the dichroic mirror frame 202 are bonded together. The thin-film flexible structure 203 and the dichroic mirror adjustment pad 204 are sequentially arranged between the dichroic mirror frame 202 and the component mounting surface 104 inside the focal plane support 1. The adhesive between the dichroic mirror 201 and the dichroic mirror frame 202 is optical epoxy. The dichroic mirror 201 is made of quartz glass with a nominal wedge angle of 0.375° (to correct aberrations introduced by dichroism and ensure image quality), a minimum thickness of 4mm, and a root mean square value of surface area better than 12nm. The dichroic mirror frame 202 is made of Invar (grade 4J32) with a coefficient of linear expansion ≤0.6×10⁻⁶. -6 The thin-film flexible structure 203 includes two pieces to isolate installation stress and ensure the surface shape of the dichroic mirror 201.

[0059] See Figure 9 The first beam-splitting mirror assembly 3 and the second beam-splitting mirror assembly 4 have the same structure. The first beam-splitting mirror assembly 3 consists of a first beam-splitting mirror 301 and a base 302. The bottom of the first beam-splitting mirror 301 is machined with a cylindrical boss, and the cylindrical surface is the bonding surface, which can significantly improve the influence of bonding stress on the surface shape of the reflective surface. The cylindrical surface of the first beam-splitting mirror 301 is bonded and fixed to the base 302 through three circumferentially distributed flexible structures 303. The three flexible structures 303 are set to eliminate the influence of component installation stress on the surface shape of the reflective surface. The adhesive is preferably optical epoxy. The material of the first beam-splitting mirror 301 is microcrystalline glass. The perpendicularity of the two reflective surfaces of the first beam-splitting mirror 301 is better than 0.005mm, and the surface shape is better than 12nm. The material of the base 302 is Invar (grade 4J32), and the coefficient of linear expansion is customized to be ≤0.6×10. -6 The beam-splitting mirror in the second beam-splitting mirror assembly 4 is designated as the second beam-splitting mirror 401.

[0060] The first spectral detector assembly 5 and the second spectral detector assembly 6 have a detection spectral range of 450nm to 600nm, while the third spectral detector assembly 7 and the fourth spectral detector assembly 8 have a detection spectral range of 600nm to 860nm.

[0061] See Figure 10 and Figure 11 The first spectral detector assembly 5, the second spectral detector assembly 6, the third spectral detector assembly 7, and the fourth spectral detector assembly 8 have the same structure and are connected to the focal plane support 1 in the same way. The first spectral detector assembly 5 consists of an area array detector 501, a detector frame 502, and a bandpass filter 503. The detector frame 502 is machined with a rectangular groove, and the area array detector 501 is installed in the rectangular groove of the detector frame 502. The actual measured dimensions of the detector package show that the size of the rectangular groove is 0.05mm to 0.1mm larger on one side than the overall dimensions of the detector. During installation, thermally conductive adhesive (preferably GD414C) is evenly applied around the area array detector 501 and then embedded into the rectangular groove of the detector frame 502 to ensure good thermal contact around the perimeter. Excess adhesive is carefully cleaned up. After the adhesive layer has cured, the bandpass filter 503 is bonded to the other side of the detector frame 502. A detector cover 505 is provided on the outside of the first spectral detector assembly 5.

[0062] See Figure 12 The first spectral detector assembly 5 is fixed to the focal plane support 1 by a detector adjustment pad 504 and screws. The front-to-back and tilt of the target surface of the area array detector 501 in the first spectral detector assembly 5 is adjusted by grinding the thickness and tilt angle of the detector adjustment pad 504. The detector adjustment pad 504 has a double-sided double-protrusion structure with a coplanarity of the double protrusions better than 0.003mm and a parallelism of the two sides better than 0.005mm. The area of ​​the protrusions is determined by thermal design analysis based on the minimum requirement value of heat conduction, reducing the difficulty of manual grinding.

[0063] The focal plane assembly also includes a reference quasi-cubic mirror assembly disposed on the second reference plane 103. The reference cubic mirror assembly 11 is a cube with a side length of 14mm. Its I face is parallel to the first reference plane 101 of the focal plane support 1, and its II face is parallel to the second reference plane 103 of the focal plane support 1. The installation error is better than 3″. The reference cubic mirror assembly 11 can be quickly aligned with the camera coordinate system when the hyperspectral focal plane is integrated with the lens.

[0064] After assembly, the hyperspectral focal plane array must undergo sinusoidal and random vibration tests (with magnitudes referring to the given satellite construction specifications) and vacuum high and low temperature cycling tests (temperature range based on the on-orbit operating temperature ±20℃) to eliminate installation and bonding stress and ensure the long-term stability of the spliced ​​focal plane.

[0065] See Figures 13-17 The present invention provides a method for stitching together a focal plane assembly of a spatial array hyperspectral camera, comprising the following steps:

[0066] Step 1: Fix the focal plane support 1 to the air-float platform using a double-sided parallel tooling aluminum block, so that the detector mounting surface 1201 of the focal plane support 1 is in a horizontal state.

[0067] Step 2: Install the positioning fixture aluminum block 1211 as a whole on the corresponding position of the focal plane support 1. Use two theodolites with orthogonal optical axes for auxiliary measurement. By calibrating the base 302 of the positioning fixture aluminum block 1211, make the coordinate system (XcYcZc) formed by the three vertical planes of the cubic mirror in the positioning fixture aluminum block 1211 parallel to the mechanical coordinate system (XmYmZm) of the focal plane support 1, with an error not exceeding 3″. The Xm axis is perpendicular to the cubic mirror assembly mounting surface 1201, the Ym axis is perpendicular to the spectral detector mounting surface 1201, and the Zm axis forms a rectangular coordinate system with the Xm and Ym axes, which conforms to the right-hand rule.

[0068] Step 3: Install the dichroic mirror assembly 2 on the corresponding position of the focal plane support 1, aim at its dichroic surface with a theodolite, and use the coordinate system formed by the reference cubic mirror as a reference to adjust the dichroic mirror 201 adjustment pad of the dichroic mirror assembly 2 so that the two-dimensional spatial angle of the dichroic surface of the dichroic mirror assembly 2 in the coordinate system formed by the reference cubic mirror of the reference cubic mirror assembly 11 has an error of no more than 3″ compared with the design value.

[0069] Specifically: The first theodolite 19 aims its first theodolite autocollimation axis 1902 at the dichroic plane of the dichroic mirror assembly 2, and the second theodolite 20 aims its second theodolite autocollimation axis 2002 at the reference cubic mirror +Zc plane. Then, the first theodolite 19 and the second theodolite 20 mutually align. The horizontal angle of rotation of the first theodolite 19 is recorded as α, that is, the angle between the mutual alignment axis 1901 and the first theodolite autocollimation axis 1902 is α, and the elevation angle reading is recorded as A. The horizontal angle of rotation of the second theodolite 20 is recorded as β, that is, the angle between the mutual alignment axis 2001 and the second theodolite autocollimation axis 2002 is β, and the elevation angle reading is recorded as B. Then, the two-dimensional angles between the dichroic plane and the Zc axis of the reference cubic mirror are as follows:

[0070] ζ=90°-α-β

[0071] η = A + B - 180°

[0072] The adjustment pad of the dichroic mirror 201 is modified to ensure that the two-dimensional spatial angles ζ and η do not exceed 3″.

[0073] Step 4: Adjust the optical axis angle of the first theodolite (19) from Step 3, so that the light emitted by the theodolite is focused by the hyperspectral camera (i.e.,...). Figure 1The incident ray (as shown in the optical path) has an incident angle deviation of no more than 5″.

[0074] Step 5: Install the first beam splitter assembly 3 on the corresponding position of the focal plane support 1. During installation, install the first beam splitter 301 and its positioning fixture aluminum block 12. The position of the beam splitter 301 is ensured by the abutment surface 1202 of the positioning fixture aluminum block 12. Specifically, first install the first beam splitter 301 onto the focal plane support 1, without tightening the screws, and then install the positioning fixture aluminum block 12. Since the positioning fixture aluminum block 12 has precise geometric dimensions, the first beam splitter 301 can be accurately positioned by fixing it in close contact with the first beam splitter. The positioning fixture aluminum block 12 includes two parallel mounting surfaces 1201 and abutment surface 1202. The abutment surface 1202 is centrally located relative to the mounting surface 1201. Mounting holes 1203 perpendicular to the mounting surface 1201 are provided at both ends of the mounting surface 1201. The mounting holes 1203 are used to mount the positioning fixture aluminum block 12 onto the focal plane support 1. The distance from the mounting surface 1201 to the abutment surface 1202 is equal to the theoretical distance from the side of the first beam splitter 301 to the mounting surface 1201 of the spectral detector assembly, and the processing accuracy is better than 0.01mm.

[0075] Step 6: Place a plane mirror 16 at the detector interface plane corresponding to the first beam splitter 301 of the first beam splitter assembly 3. The reflective surface of the plane mirror 16 is in contact with the detector interface plane. Repair the base 302 of the first beam splitter assembly 3 so that the crosshair returned image 15 of the theodolite through the plane mirror 16 in step 4 coincides with the reference crosshair 14, with a bidirectional error not exceeding 2″.

[0076] Step 7: Repeat the operations of Step 5 and Step 6 to install the second beam splitter assembly 4; that is, install the second beam splitter assembly 4 on the corresponding position of the focal plane support 1, place a plane mirror 16 at the detector interface plane corresponding to the second beam splitter 401 of the second beam splitter assembly 4, the reflective surface of the plane mirror 16 is in contact with the detector interface plane, and repair the base 302 of the second beam splitter assembly 4 so that the crosshair returned image 15 of the theodolite through the plane mirror 16 in Step 4 coincides with the reference crosshair 14, and the bidirectional error does not exceed 2″;

[0077] Step 8: Connect the focal plane support 1 to the three-dimensional precision adjustment frame 17 via the splicing fixture 13, and fix it under the splicer lens 1801. Use the three-dimensional precision adjustment frame 17 to adjust the focal plane support 1 so that the coordinate system (XcYcZc) of the reference cubic mirror is parallel to the coordinate system (XpYpZp) of the splicer 18, with an error not exceeding 5″. Then, use a theodolite to assist in measurement and adjust the focal plane support 1 to rotate by an angle θ along the major axis (Yp) of the splicer 18, while keeping the other two dimensions unchanged, so that the splicer 18 can observe the complete target surface of the detector and the focal plane support 1. The space does not interfere with each other; the splicing fixture 13 includes a fixture mounting base 1301 and a fixing frame 1302 vertically fixed on the upper surface of the mounting base; one side of the fixing frame 1302 is a reference vertical plane 1303, the other side is an inclined plane 1304, and the upper surface is a reference horizontal plane 1305; the existence of these three planes ensures that the initial accuracy of the focal plane support 1 is high when it is installed with it, wherein the reference horizontal plane 1305 and the reference vertical plane 1303 are reference planes for measuring the relative angle relationship; the bottom surface of the focal plane support 1 and the inclined plane 1304 of the splicing fixture 13 are fixedly connected.

[0078] Step 9: Install the first spectral detector assembly 5. Select the four corner pixels of the photosensitive surface of the area array detector 501 of the first spectral detector assembly 5 as the stitching aiming objects. Define the coordinates of the four pixels as (0,0), (0,1), (1,0) and (1,1). Using pixel (0,0) as the reference, measure the relative defocus of the other three pixels by the defocus method. Repair the detector adjustment pad 504 of the spectral detector assembly so that pixel (1,0) is coplanar with pixel (0,0) with an error not exceeding 0.003mm, pixel (1,1) is coplanar with pixel (0,1) with an error not exceeding 0.003mm, and the relative defocus of pixel (0,1) and pixel (0,0) and the relative defocus of pixel (1,1) and pixel (1,0) does not exceed 0.003mm.

[0079] The relative defocus amount Δh is determined by the following formula:

[0080] Δh=n×a×tanθ

[0081] In the formula: n is the number of pixel columns of the spectral detector;

[0082] a is the pixel size of the spectral detector;

[0083] θ is the rotation angle described in step eight;

[0084] Step 10: Repeat step 9 to install the second spectral detector assembly 6, the third spectral detector assembly 7, and the fourth spectral detector assembly 8. The repair and measurement of the second spectral detector assembly 6, the third spectral detector assembly 7, and the fourth spectral detector assembly 8 are all based on the four corner pixels of the first spectral detector assembly 5.

[0085] Step 11: Adjust the positions of the second spectral detector assembly 6, the third spectral detector assembly 7, and the fourth spectral detector assembly 8 installed in Step 10, so that the first spectral detector assembly 5 and the second spectral detector assembly 6 are spliced ​​together to form the first target surface according to the specified number of overlapping pixels; the third spectral detector assembly 7 and the fourth spectral detector assembly 8 are spliced ​​together to form the second target surface according to the specified number of overlapping pixels; the bidirectional positional deviation between the first target surface and the second target surface does not exceed 0.002mm, and the detector splicing is completed.

Claims

1. A method for stitching together focal plane components of a spatial array hyperspectral camera, characterized in that, Includes the following steps: Step 1: Fix the focal plane support (1) to the air-float platform using a double-sided parallel tooling aluminum block, so that the detector mounting surface (1201) of the focal plane support (1) is horizontal. Step 2: Install the reference cubic mirror assembly (11) as a whole on the corresponding position of the focal plane support (1), so that the coordinate system formed by the three vertical planes of the cubic mirror in the reference cubic mirror assembly (11) is parallel to the mechanical coordinate system of the focal plane support (1), with an error not exceeding 3″. Step 3: Install the dichroic mirror assembly (2) on the corresponding position of the focal plane support (1), aim at its dichroic surface with a theodolite, and use the coordinate system formed by the reference cubic mirror as the reference to adjust the dichroic mirror (201) adjustment pad of the dichroic mirror assembly (2) so that the two-dimensional spatial angle of the dichroic surface of the dichroic mirror assembly 2 in the coordinate system formed by the reference cubic mirror of the reference cubic mirror assembly 11 does not exceed 3″ compared with the design value. Step 4: Adjust the optical axis angle of the theodolite mentioned in Step 3 so that the incident angle deviation of the light emitted by the theodolite and the hyperspectral camera does not exceed 5″. Step 5: Install the first beam splitter assembly (3) on the corresponding position of the focal plane support (1); Step 6: Place a plane mirror (16) at the detector interface plane corresponding to the first beam splitter (301) of the first beam splitter assembly (3). The reflective surface of the plane mirror (16) is in contact with the detector interface plane. Repair the base (302) of the first beam splitter assembly (3) so that the crosshair return image (15) of the theodolite described in step 4 through the plane mirror (16) coincides with the reference crosshair (14), and the bidirectional error does not exceed 2″. Step 7: Repeat steps 5 and 6 to install the second beam-splitting mirror assembly (4); Step 8: Connect the focal plane support (1) to the three-dimensional precision adjustment frame (17) through the splicing fixture (13), and fix it under the splicer lens (1801) so that the splicer (18) can observe the complete target surface of the detector and does not interfere with the focal plane support (1) in space. Step 9: Install the first spectral detector assembly (5), select the four corner pixels of the photosensitive surface of the array detector (501) of the first spectral detector assembly (5) as the stitching aiming objects, define the coordinates of the four pixels as (0,0), (0,1), (1,0) and (1,1), and measure the relative defocus of the other three pixels by using the defocus method with pixel (0,0) as the reference. Adjust the detector adjustment pad (504) of the first spectral detector assembly (5) so that pixel (1,0) and pixel (0,0) are coplanar with an error not exceeding 0.003mm, pixel (1,1) and pixel (0,1) are coplanar with an error not exceeding 0.003mm, and the relative defocus of pixel (0,1) and pixel (0,0) and the relative defocus of pixel (1,1) and pixel (1,0) do not exceed 0.003mm. Step 10: Repeat step 9 to install the second spectral detector assembly (6), the third spectral detector assembly (7) and the fourth spectral detector assembly (8). The repair and measurement of the second spectral detector assembly (6), the third spectral detector assembly (7) and the fourth spectral detector assembly (8) are based on the four corner pixels of the first spectral detector assembly (5). Step 11: Adjust the positions of the second spectral detector assembly (6), the third spectral detector assembly (7), and the fourth spectral detector assembly (8) installed in Step 10, so that the first spectral detector assembly (5) and the second spectral detector assembly (6) are spliced ​​together to form the first target surface according to the specified number of overlapping pixels; the third spectral detector assembly (7) and the fourth spectral detector assembly (8) are spliced ​​together to form the second target surface according to the specified number of overlapping pixels; the bidirectional positional deviation between the first target surface and the second target surface does not exceed 0.002mm, and the detector splicing is completed.

2. The method for stitching together a focal plane assembly of a spatial array hyperspectral camera according to claim 1, characterized in that, The installation process of the reference cubic mirror assembly (11) in step two is as follows: auxiliary measurement is performed using two theodolites with orthogonal optical axes, and the error accuracy is ensured by repairing the base (302) of the reference cubic mirror assembly (11).

3. The method for stitching together a focal plane assembly of a spatial array hyperspectral camera according to claim 1, characterized in that, When installing the first beam splitter assembly (3) described in step five, the first beam splitter (301) and its positioning tool aluminum block (12) are installed. The position of the beam splitter of the first beam splitter assembly (3) is ensured by the abutment surface (1202) of the positioning tool aluminum block (12). The positioning tooling aluminum block (12) includes two parallel mounting surfaces (1201) and a backing surface (1202). The backing surface (1202) is centered relative to the mounting surface (1201). The mounting surface (1201) has mounting holes (1203) perpendicular to the mounting surface (1201) at both ends.

4. The method for stitching together a focal plane assembly of a spatial array hyperspectral camera according to claim 1, characterized in that, The splicing fixture (13) described in step eight includes a fixture mounting base (1301) and a fixing frame (1302) that is vertically fixed on the upper surface of the fixture mounting base; one side of the fixing frame (1302) is a reference vertical plane (1303), the other side is an inclined plane (1304), and the upper surface is a reference horizontal plane (1305); the bottom surface of the focal plane support (1) and the inclined plane (1304) of the splicing fixture (13) are fixedly connected.

5. The method for stitching together a focal plane assembly of a spatial array hyperspectral camera according to claim 1, characterized in that, The adjustment process of the focal plane support (1) on the three-dimensional precision adjustment frame (17) in step eight is as follows: the focal plane support (1) is adjusted using the three-dimensional precision adjustment frame (17) so that the coordinate system of the reference cubic mirror is parallel to the coordinate system of the splicing instrument (18) with an error not exceeding 5″. Then, the focal plane support (1) is rotated by an angle θ along the long axis of the splicing instrument (18) with the theodolite as an auxiliary measurement, while the angles in the other two dimensions remain unchanged, so that the splicing instrument (18) can observe the complete target surface of the detector and does not interfere with the focal plane support (1) in space.

6. The method for stitching together a focal plane assembly of a spatial array hyperspectral camera according to claim 5, characterized in that, The relative defocus amount Δh mentioned in step nine is determined by the following formula: Δh=n×a×tanθ In the formula: n is the number of pixel columns of the spectral detector; a is the pixel size of the spectral detector; θ is the rotation angle described in step eight.

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