Splicing method for focal plane assembly of space area array hyperspectral camera

Abstract

The invention discloses a splicing method for focal plane components of a spatial area array hyperspectral camera, belongs to the technical field of spatial remote sensing, and aims to solve the problems in the prior art. According to the splicing method, splicing is conducted through splicing equipment composed of a three-dimensional precise adjusting frame and a splicing instrument, a splicing tool and a positioning tool aluminum block, and meanwhile alignment and positioning are conducted through a theodolite during splicing; the reference cubic mirror assembly, the dichroic mirror assembly, the first light splitting reflector assembly, the second light splitting reflector assembly, the first spectrum detector assembly, the second spectrum detector assembly, the third spectrum detector assembly and the fourth spectrum detector assembly are sequentially installed on the focal plane support.

Description

Technical Field

[0001] The invention belongs to the technical field of space remote sensing, and in particular relates to a method for splicing focal plane components of a space array hyperspectral camera. Background Art

[0002] The miniaturization of satellites and space cameras is an important trend in the current field of space remote sensing. It is an important prerequisite for realizing the technology of launching multiple satellites with one rocket, saving development and launch costs, and shortening the development cycle. Miniaturization is to some extent contrary to the observation efficiency of space cameras. The limitations of aperture and field of view severely restrict the installation and layout of many functional units of small space cameras.

[0003] Hyperspectral remote sensing has outstanding advantages in the fine classification and identification of ground objects. It has become an important technical means for space-based reconnaissance and has played an important role in the identification and analysis of camouflaged targets and true and false targets on the ground and at sea. Due to the problem of spectral band setting and detector matching, it is usually necessary to use spectroscopic form to ensure the installation space of all detectors. Generally, there are two methods: field of view spectroscopic and rear working distance spectroscopic. Field of view spectroscopic refers to a spectroscopic form that uses a reflector to split a wide spectral band beam into different imaging areas, so that different spectral bands of light are incident on the corresponding detectors respectively. This spectroscopic form requires the optical system to have sufficient field of view in the spectroscopic direction to avoid blocking the imaging beam; rear working distance spectroscopic is to use one (or more) color separation mirrors in the rear working distance of the main optical system to achieve the spectroscopic separation of two wide spectral bands by reflecting spectral band 1 and transmitting spectral band 2. When a single-chip array detector cannot meet the limited field of view, it is necessary to combine the two spectroscopic methods, resulting in a compact and complex spectral focal plane. Based on the requirements of spectral band registration, the position alignment accuracy of the detectors in each spectral band is required to be better than 2μm, and the coplanarity is better than 5μm, which places extremely high demands on detector splicing. Since multiple spectroscopic operations require sufficient working distance, the front working distance of a high-resolution tool microscope is difficult to meet the operational requirements, and there is a problem of interference with the focal plane components when the microscope lens moves. Summary of the invention

[0004] The purpose of the present invention is to propose a method for splicing focal plane components of a spatial array hyperspectral camera that is suitable for limited spatial volume, highly folded optical paths, integration, and multiple detectors, so as to solve the problems existing in the prior art.

[0005] To achieve the above object, a method for splicing focal plane components of a spatial array hyperspectral camera of the present invention comprises the following steps:

[0006] Step 1: Fix the focal plane bracket on the air-floating platform through a double-sided parallel tooling aluminum block so that the detector mounting surface of the focal plane bracket is in a horizontal state;

[0007] Step 2: Install the reference cubic mirror assembly as a whole on the corresponding position of the focal plane bracket, so that the coordinate system formed by the three vertical surfaces of the cubic mirror in the reference cubic mirror assembly is parallel to the mechanical coordinate system of the focal plane bracket, and the error does not exceed 3″;

[0008] Step 3: Install the dichroic mirror assembly at the corresponding position of the focal plane bracket, 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 error of the two-dimensional spatial angle of the dichroic mirror surface of the dichroic mirror assembly in the coordinate system formed by the reference cubic mirror of the reference cubic mirror assembly is no more than 3″ compared with the design value;

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

[0010] Step 5: Install the first beam splitting reflector assembly on the corresponding position of the focal plane bracket;

[0011] Step 6: placing a plane reflector at the detector interface plane corresponding to the first beam splitter reflector of the first beam splitter reflector assembly, with the reflective surface of the plane reflector in contact with the detector interface plane, and grinding the base of the first beam splitter reflector assembly so that the crosshair return image of the theodolite described in step 4 through the plane reflector coincides with the reference crosshair, and the two-way error does not exceed 2″;

[0012] Step 7: Repeat the operations of step 5 and step 6 to install the second beam splitting reflector assembly;

[0013] Step 8: Connect the focal plane bracket to the three-dimensional precision adjustment frame through the splicing tooling, and fix it under the lens of the splicing instrument, so that the splicing instrument can observe the complete target surface of the detector and does not interfere with the space of the focal plane bracket;

[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), and measure the relative defocus of the other three pixels by the defocus method with pixel (0,0) as the reference, and repair the detector adjustment pad of the first spectral detector assembly so that the pixel (1,0) and the pixel (0,0) are coplanar with an error of no more than 0.003mm, the pixel (1,1) and the pixel (0,1) are coplanar with an error of no more than 0.003mm, and the relative defocus of the pixel (0,1) and the pixel (0,0) and the relative defocus of the pixel (1,1) and the pixel (1,0) do not exceed 0.003mm;

[0015] Step 10: Repeat step 9 to install the second spectrum detector assembly, the third spectrum detector assembly and the fourth spectrum detector assembly. The research and measurement of the second spectrum detector assembly, the third spectrum detector assembly and the fourth spectrum detector assembly are based on the four corner pixel elements of the first spectrum detector assembly;

[0016] Step 11: Adjust the positions of the second spectral detector assembly, the third spectral detector assembly and the fourth spectral detector assembly installed in step 10, so that the first spectral detector assembly and the second spectral detector assembly are spliced ​​into the first target surface according to the specified number of overlapping pixels; the third spectral detector assembly and the fourth spectral detector assembly are spliced ​​into the second target surface according to the specified number of overlapping pixels; the two-way position deviation of the first target surface and the second target surface does not exceed 0.002mm, and the detector splicing is completed.

[0017] The installation process of the reference cubic mirror assembly described in step 2 is: using two theodolites with orthogonal optical axes to perform auxiliary measurement, and ensuring the error accuracy by repairing the base of the reference cubic mirror assembly.

[0018] When installing the first beam splitter reflector assembly described in step 5, install the first beam splitter reflector and its positioning tooling aluminum block, and ensure the position of the beam splitter reflector of the first beam splitter reflector assembly by the leaning surface of the positioning tooling aluminum block;

[0019] The positioning tooling aluminum block comprises two mutually parallel mounting surfaces and a supporting surface, the supporting surface is centrally arranged relative to the mounting surface, and mounting holes perpendicular to the mounting surface are arranged at both ends of the mounting surface.

[0020] The splicing tooling described in step eight includes a tooling mounting seat and a fixing frame vertically fixed on the upper surface of the working mounting seat; one side of the fixing frame is a reference plumb 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 tooling.

[0021] The adjustment process of the focal plane bracket on the three-dimensional precision adjustment frame described in step eight is: use the three-dimensional precision adjustment frame to adjust the focal plane bracket so that the coordinate system of the reference cubic mirror is parallel to the coordinate system of the splicing instrument, and the error does not exceed 5", and then use the theodolite to assist in measurement and adjust the focal plane bracket to rotate by an angle θ along the long axis direction of the splicing instrument, while keeping the other two-dimensional angles unchanged, so that the splicing instrument can observe the complete target surface of the detector and does not interfere with the space of the focal plane bracket.

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

[0023] Δh=n×a×tanθ

[0024] Wherein: 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 deflection angle described in step eight.

[0027] The beneficial effects of the present invention are as follows: a method for splicing focal plane components of a spatial array hyperspectral camera of the present invention applies spatial intersection measurement and self-collimation optical measurement methods to the precise positioning of focal plane components, thereby solving the splicing problem of focal plane components of a compact multi-detector spatial array hyperspectral camera; a tilt reference method is adopted to solve the problem of insufficient working distance in front of a high-resolution tool microscope during splicing, and the method is particularly suitable for complex focal plane components with limited spatial volume, long optical paths and multiple folds, and has the characteristics of simple principle and high precision. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0031] Figure 4 The left view of the focal plane assembly structure of a spatial array hyperspectral camera without the aperture piece;

[0032] Figure 5 A schematic structural diagram showing a side view of a focal plane bracket in a focal plane assembly of a spatial array hyperspectral camera;

[0033] Figure 6 A schematic structural diagram showing another side of a focal plane bracket in a focal plane assembly of a spatial array hyperspectral camera;

[0034] Figure 7 It is a bottom view of a focal plane support in a focal plane assembly of a spatial array hyperspectral camera;

[0035] Figure 8 It is a schematic diagram of the structure of a color separation mirror component in a focal plane component of a spatial array hyperspectral camera;

[0036] Fig. 9 It is a schematic diagram of the structure of a beam splitter reflector assembly in a focal plane assembly of a spatial array hyperspectral camera;

[0037] Fig.10 It is a side schematic diagram of a spectral detector component in a focal plane component of a spatial array hyperspectral camera;

[0038] Fig.11It is another side view schematic diagram of a spectral detector assembly in a focal plane assembly of a spatial array hyperspectral camera;

[0039] Fig.12 A schematic diagram of the structure of a detector adjustment pad in a focal plane assembly of a spatial array hyperspectral camera;

[0040] Fig.13 It is a principle diagram of measuring the installation angle of the dichroic mirror in a method for splicing focal plane components of a spatial array hyperspectral camera of the present invention;

[0041] Fig.14 A schematic diagram of the measurement principle of the installation angle of the beam splitter reflector in a method for splicing focal plane components of a spatial array hyperspectral camera of the present invention;

[0042] Fig.15 It is a schematic diagram of the structure of the aluminum block of the positioning tooling in the method for splicing the focal plane assembly of a spatial array hyperspectral camera of the present invention;

[0043] Fig.16 It is a schematic diagram of a splicing tooling structure in a method for splicing focal plane components of a spatial array hyperspectral camera of the present invention;

[0044] Fig.17 It is a schematic diagram of a splicing device in a method for splicing focal plane components of a spatial array hyperspectral camera of the present invention;

[0045] Fig.18 It is a schematic diagram of spectral detector splicing in a method for splicing focal plane components of a spatial array hyperspectral camera of the present invention;

[0046] Wherein: 1. focal plane bracket, 101. first reference plane, 102. first parallel plane, 103. second reference plane, 104. component mounting surface, 105. glue injection hole, 106. prefabricated pin hole, 2. color separation mirror assembly, 201. color separation mirror, 202. color separation mirror frame, 203. thin-film flexible structure, 204. color separation mirror adjustment pad, 3. first beam splitter reflector assembly, 301. first beam splitter reflector, 302. base, 303. flexible structure, 4. second beam splitter reflector assembly, 401. second beam splitter reflector, 5. first spectrum detector assembly, 501. array detector, 502. detector frame, 503. bandpass filter, 504. detector adjustment pad, 505. detector cover, 506. first spectrum image plane, 6. second spectrum detector assembly, 601. second spectrum image plane, 7. third spectrum detector assembly Components, 701, third spectrum image plane, 8, fourth spectrum detector assembly, 801, fourth spectrum image plane, 9, dust cover, 10, aperture piece, 11, reference cubic mirror assembly, 12, positioning tooling aluminum block, 1201, mounting surface, 1202, leaning surface, 1203, mounting hole, 13, splicing tooling, 1301, tooling mounting seat, 1302, fixing frame, 1303, reference plumb plane, 1304, inclined plane, 1305. Reference horizontal plane; 14. Reference crosshairs; 15. Return image; 16. Plane reflector; 17. Three-dimensional precision adjustment frame; 18. Splicer; 1801. Splicer lens; 19. The first theodolite; 1901. Mutual aiming optical axis of the first theodolite; 1902. Auto-alignment optical axis of the first theodolite; 20. The second theodolite; 2001. Mutual aiming optical axis of the second theodolite; 2002. Auto-alignment optical axis of the second theodolite. DETAILED DESCRIPTION

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

[0048] See also Figure 1-Figure 7 A focal plane assembly of a spatial array hyperspectral camera of the present invention comprises:

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

[0050] The dichroic mirror assembly 2 is positioned and installed on the internal assembly mounting surface 104 of the focal plane bracket 1 through the prefabricated pin hole 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, with a reflection band of 450nm to 600nm and a transmission band of 600nm to 860nm;

[0051] A first beam splitter reflector assembly 3 and a second beam splitter reflector assembly 4 are installed in the focal plane bracket 1 and positioned by injection molding through the injection hole 105, and the first beam splitter reflector assembly 3 and the second beam splitter reflector assembly 4 receive the reflected light and the transmitted light of the dichroic mirror assembly 2 respectively;

[0052] Four groups of spectral detector assemblies with the same structure 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 spectroscopic reflector assembly 3, and the third spectral detector assembly 7 and the fourth spectral detector assembly 8 are symmetrical with respect to the second spectroscopic reflector assembly 4;

[0053] An aperture piece 10 arranged at the light entrance of the focal plane support 1;

[0054] and a dust cover 9 arranged at the upper end of the focal plane support 1;

[0055] The incident light irradiates the dichroic mirror 201 of the dichroic mirror assembly 2 after passing through the aperture piece, and the light reflected by the dichroic mirror 201 irradiates the first beam splitting reflector assembly 3, and after being split by the first beam splitting reflector assembly 3, it irradiates the corresponding two groups of area array detectors 501 of spectral detector assemblies, that is, 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 transmitted by the dichroic mirror 201 irradiates the second beam splitting reflector assembly 4, and after being split by the second beam splitting reflector assembly 4, it irradiates the corresponding two groups of area array detectors 501 of spectral detector assemblies, that is, 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 plane 101 of the focal plane bracket 1 is composed of four coplanar rectangular bosses with a coplanarity better than 0.003 mm; the flatness of the second reference plane 103 is better than 0.003 mm, and the flatness of the component mounting surface 104 is better than 0.003 mm.

[0057] The diameter of the injection hole 105 is Φ2.5mm, and optical epoxy glue is injected into the mounting interface corresponding to the first beam splitter reflector assembly 3 and the second beam splitter reflector assembly 4 and the focal plane bracket 1 through the injection hole 105 for bonding, curing and positioning; the diameter of the prefabricated pin hole 106 is Φ2.8mm, and the pin is connected and positioned with the dichroic mirror assembly 2 through the prefabricated pin hole 106 on the focal plane bracket 1. The reason why the first beam splitter reflector assembly 3, the second beam splitter reflector assembly 4 and the dichroic mirror assembly 2 adopt the above two positioning methods is that the positioning accuracy will be slightly lost when the pin is drilled. In order to ensure the final splicing accuracy of the detector under the splicing instrument, the use of optical epoxy glue is the most reliable.

[0058] See also Figure 8 The dichroic mirror assembly 2 comprises a dichroic mirror 201, a dichroic mirror frame 202, a thin sheet flexible structure 203 and a dichroic mirror adjustment pad 204; the dichroic mirror 201 and the dichroic mirror frame 202 are bonded and assembled; the thin sheet 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 bracket 1; the adhesive between the dichroic mirror 201 and the dichroic mirror frame 202 is an optical epoxy glue; the dichroic mirror 201 is made of quartz glass, has a nominal wedge angle of 0.375° (in order to correct the aberration introduced by color separation and ensure the imaging quality), a minimum thickness of 4mm, and a surface root mean square value better than 12nm; the dichroic mirror frame 202 is made of Invar (grade 4J32), and the linear expansion coefficient is customized to be ≤0.6×10 -6 The thin-sheet flexible structure 203 includes two sheets, which are used to isolate the installation stress and ensure the surface shape of the dichroic mirror 201.

[0059] See also Fig. 9 The first beam splitter reflector assembly 3 and the second beam splitter reflector assembly 4 have the same structure. The first beam splitter reflector assembly 3 is composed of a first beam splitter reflector 301 and a base 302. The bottom of the first beam splitter reflector 301 is processed with a cylindrical boss, and the cylindrical surface is a bonding surface, which can significantly improve the influence of bonding stress on the surface shape of the reflecting surface. The cylindrical surface of the first beam splitter reflector 301 is bonded and fixed to the base 302 through three flexible structures 303 evenly distributed around the circumference. The three flexible structures 303 are provided to eliminate the influence of component installation stress on the surface shape of the reflecting surface; the adhesive is preferably optical epoxy glue, the material of the first beam splitter reflector 301 is microcrystalline glass, the verticality of the two reflecting surfaces of the first beam splitter reflector 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 linear expansion coefficient is customized to be ≤0.6×10 -6 The beam splitter reflector in the second beam splitter reflector assembly 4 is marked as a second beam splitter reflector 401 .

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

[0061] See also Fig.10 and Fig.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 in the same way as the focal plane bracket 1; the first spectral detector assembly 5 is composed of a planar array detector 501, a detector frame 502 and a bandpass filter 503; the detector frame 502 is processed with a rectangular groove, and the planar array detector 501 is installed in the rectangular groove of the detector frame 502. The detector package dimensions are measured, and the rectangular groove size is 0.05mm to 0.1mm larger than the detector dimensions on one side; during installation, the planar array detector 501 is evenly coated with thermal conductive glue (preferably GD414C) around it and then embedded in the rectangular groove of the detector frame 502 to ensure good thermal contact around it, and the overflowed glue is carefully cleaned. The bandpass filter 503 is bonded to the other side of the detector frame 502 after the glue layer is cured, and a detector cover 505 is provided on the outside of the first spectral detector assembly 5.

[0062] See also Fig.12 The first spectral detector assembly 5 is fixed on the focal plane bracket 1 through the detector adjustment pad 504 and fixed by screws. The front and back and inclination of the target surface of the array detector 501 in the first spectral detector assembly 5 are adjusted by grinding the thickness and inclination of the detector adjustment pad 504; the detector adjustment pad 504 is a double-sided double-boss structure, the coplanarity of the double boss is better than 0.003mm, and the parallelism of the two sides is better than 0.005mm. The boss area is given a minimum requirement value according to the heat conduction requirements after thermal design analysis, which reduces the difficulty of manual grinding.

[0063] The focal plane assembly also includes a reference quasi-cubic mirror assembly arranged on the second reference plane 103. The reference cubic mirror assembly 11 is a cube with a side length of 14 mm, whose I surface is parallel to the first reference plane 101 of the focal plane bracket 1, and whose II surface is parallel to the second reference plane 103 of the focal plane bracket 1. The installation error is better than 3". The reference cubic mirror assembly 11 is used to quickly align with the camera coordinate system when the hyperspectral focal plane is integrated with the lens.

[0064] After assembly, the array hyperspectral focal plane assembly must undergo sinusoidal and random vibration tests (the magnitude of which refers to the given satellite construction specifications) and vacuum high and low temperature cycle tests (the temperature range is based on the on-orbit operating temperature ±20°C) to eliminate installation and bonding stresses and ensure the long-term stability of the spliced ​​focal plane.

[0065] See also Figure 13-Figure 17 A method for splicing focal plane components of a spatial array hyperspectral camera of the present invention comprises the following steps:

[0066] Step 1: fix the focal plane bracket 1 on the air-floating platform through a double-sided parallel aluminum tooling block, so that the detector mounting surface 1201 of the focal plane bracket 1 is in a horizontal state;

[0067] Step 2: Install the positioning tool aluminum block 1211 as a whole at the corresponding position of the focal plane bracket 1, and use two theodolites with orthogonal optical axes to perform auxiliary measurement. By repairing the base 302 of the positioning tool aluminum block 1211, the coordinate system (XcYcZc) formed by the three vertical planes of the cubic mirror in the positioning tool aluminum block 1211 is parallel to the mechanical coordinate system (XmYmZm) of the focal plane bracket 1, and the error does not exceed 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, the Xm axis and the Ym axis form a rectangular coordinate system, which conforms to the right-hand rule;

[0068] Step 3: Install the dichroic mirror assembly 2 at the corresponding position of the focal plane bracket 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 error of the two-dimensional spatial angle of the dichroic mirror surface of the dichroic mirror assembly 2 in the coordinate system formed by the reference cubic mirror of the reference cubic mirror assembly 11 is no more than 3" compared with the design value;

[0069] Specifically, the first theodolite autocollimation optical axis 1902 of the first theodolite 19 is aimed at the color separation surface of the color separation mirror assembly 2, and the second theodolite autocollimation optical axis 2002 of the second theodolite 20 is aimed at the reference cubic mirror +Zc surface, and then the first theodolite 19 and the second theodolite 20 are aimed at each other, the horizontal angle of rotation of the first theodolite 19 is recorded as α, that is, the angle between the first theodolite mutual aiming optical axis 1901 and the first theodolite autocollimation optical 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 second theodolite mutual aiming optical axis 2001 and the second theodolite autocollimation optical axis 2002 is β, and the elevation angle reading is recorded as B, then the two-dimensional angles between the color separation surface and the Zc axis of the reference cubic mirror are respectively:

[0070] ζ=90°-α-β

[0071] η=A+B-180°

[0072] The dichroic mirror 201 is adjusted by grinding the adjustment pads so 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 in step 3 so that the light emitted by the theodolite is directed to the hyperspectral camera (i.e. Figure 1The incident light of the optical path shown in the figure shall not deviate from the incident angle by more than 5″;

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

[0075] Step 6: Place a plane reflector 16 at the detector interface plane corresponding to the first beam splitter reflector 301 of the first beam splitter reflector assembly 3, the reflective surface of the plane reflector 16 is in contact with the detector interface plane, and repair the base 302 of the first beam splitter reflector assembly 3 so that the crosshair return image 15 of the theodolite described in step 4 through the plane reflector 16 coincides with the reference crosshair 14, and the two-way error does not exceed 2″;

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

[0077] Step 8: Connect the focal plane bracket 1 to the three-dimensional precision adjustment frame 17 through the splicing tool 13, and fix it under the splicing instrument lens 1801. Use the three-dimensional precision adjustment frame 17 to adjust the focal plane bracket 1 so that the coordinate system (XcYcZc) of the reference cubic mirror is parallel to the coordinate system (XpYpZp) of the splicing instrument 18, and the error does not exceed 5", and then use the theodolite to assist in measurement, and adjust the focal plane bracket 1 to rotate by an angle θ along the long axis (Yp) direction of the splicing instrument 18, and the other two-dimensional angles remain unchanged, so that the splicing instrument 18 can observe the complete target surface of the detector and is aligned with the focal plane bracket 1. The space does not interfere; the splicing tool 13 includes a tool mounting seat 1301 and a fixing frame 1302 vertically fixed on the upper surface of the working mounting seat; one side of the fixing frame 1302 is a reference plumb 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 surfaces is to ensure that the initial accuracy of the focal plane bracket 1 is high when it is installed with them, wherein the reference horizontal plane 1305 and the reference plumb plane 1303 are the measurement reference planes of the relative angle relationship; the bottom surface of the focal plane bracket 1 is fixedly connected to the inclined plane 1304 of the splicing tool 13;

[0078] Step nine: 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), respectively, and measure the relative defocus of the remaining three pixels by the defocus method with pixel (0,0) as the reference, and repair the detector adjustment pad 504 of the spectral detector assembly so that the pixel (1,0) and the pixel (0,0) are coplanar, and the error does not exceed 0.003mm, the pixel (1,1) and the pixel (0,1) are coplanar, and the error does not exceed 0.003mm, and the relative defocus of the pixel (0,1) and the pixel (0,0) and the relative defocus of the pixel (1,1) and the pixel (1,0) do not exceed 0.003mm;

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

[0080] Δh=n×a×tanθ

[0081] Wherein: 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 deflection angle described in step eight;

[0084] Step 10: Repeat step 9 to install the second spectrum detector assembly 6, the third spectrum detector assembly 7 and the fourth spectrum detector assembly 8. The research and measurement of the second spectrum detector assembly 6, the third spectrum detector assembly 7 and the fourth spectrum detector assembly 8 are based on the four corner pixels of the first spectrum 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 ​​into the first target surface according to the prescribed number of overlapping pixels; the third spectral detector assembly 7 and the fourth spectral detector assembly 8 are spliced ​​into the second target surface according to the prescribed number of overlapping pixels; the two-way position deviation of 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 splicing focal plane components of a spatial array hyperspectral camera, characterized in that: The following steps are involved: Step 1: fix the focal plane support (1) on the air-floating platform through 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; Step 2: Install the reference cubic mirror assembly (11) as a whole at the corresponding position of the focal plane bracket (1), so that the coordinate system formed by the three vertical surfaces of the cubic mirror in the reference cubic mirror assembly (11) is parallel to the mechanical coordinate system of the focal plane bracket (1), and the error does not exceed 3″; Step 3: Install the dichroic mirror assembly (2) at the corresponding position of the focal plane bracket (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 error of 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 compared with the design value does not exceed 3"; Step 4: Adjust the angle of the optical axis of the theodolite in step 3 so that the incident angle deviation of the incident light of the light array hyperspectral camera emitted by the theodolite does not exceed 5″; Step 5: Install the first beam splitting reflector assembly (3) at a corresponding position of the focal plane bracket (1); Step 6: placing a plane reflector (16) at the detector interface plane corresponding to the first beam splitter reflector (301) of the first beam splitter reflector assembly (3), with the reflective surface of the plane reflector (16) in contact with the detector interface plane, and repairing the base (302) of the first beam splitter reflector assembly (3) so that the crosshair return image (15) of the theodolite described in step 4 through the plane reflector (16) coincides with the reference crosshair (14), and the two-way error does not exceed 2″; Step 7: Repeat the operations of step 5 and step 6 to install the second beam splitting reflector assembly (4); Step 8: Connect the focal plane support (1) to the three-dimensional precision adjustment frame () through the splicing tool (13), and fix it under the splicing instrument lens (1801), 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; Step nine: installing the first spectral detector assembly (5), selecting four corner pixel points of the photosensitive surface of the array detector (501) of the first spectral detector assembly (5) as stitching aiming objects, defining the coordinates of the four pixels as (0,0), (0,1), (1,0) and (1,1), respectively, taking the pixel (0,0) as the reference, determining the relative defocus of the other three pixels by the defocus method, and repairing the detector adjustment pad (504) of the first spectral detector assembly (5) so that the pixel (1,0) and the pixel (0,0) are coplanar with an error of no more than 0.003 mm, the pixel (1,1) and the pixel (0,1) are coplanar with an error of no more than 0.003 mm, and the relative defocus of the pixel (0,1) and the pixel (0,0) and the relative defocus of the pixel (1,1) and the pixel (1,0) do not exceed 0.003 mm; Step 10: Repeat step 9 to install the second spectrum detector assembly (6), the third spectrum detector assembly (7) and the fourth spectrum detector assembly (8), wherein the research and measurement of the second spectrum detector assembly (6), the third spectrum detector assembly (7) and the fourth spectrum detector assembly (8) are based on the four corner pixel elements of the first spectrum 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 ​​into a first target surface according to the prescribed number of overlapping pixels; the third spectral detector assembly (7) and the fourth spectral detector assembly (8) are spliced ​​into a second target surface according to the prescribed number of overlapping pixels; the two-way position deviation between the first target surface and the second target surface does not exceed 0.002 mm, and the detector splicing is completed.

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

3. The method for splicing focal plane components of a spatial array hyperspectral camera according to claim 1, characterized in that: When installing the first beam splitter reflector assembly (3) described in step five, the first beam splitter reflector (301) and its positioning tool aluminum block (12) are installed, and the beam splitter reflector position of the first beam splitter reflector assembly (3) is ensured by the support surface (1202) of the positioning tool aluminum block (12); The positioning tool aluminum block (12) comprises two mounting surfaces (1201) and a support surface (1202) arranged parallel to each other, wherein the support surface (1202) is arranged centrally relative to the mounting surface (1201), and mounting holes (1203) perpendicular to the mounting surface (1201) are arranged at both ends of the mounting surface (1201).

4. The method for splicing focal plane components of a spatial array hyperspectral camera according to claim 1, characterized in that: The splicing tool (13) described in step eight includes a tool mounting seat (1301) and a fixing frame (1302) vertically fixed on the upper surface of the working mounting seat; one side of the fixing frame (1302) is a reference plumb 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 bracket (1) and the inclined plane (1304) of the splicing tool (13) are fixedly connected.

5. The method for splicing focal plane components of a spatial array hyperspectral camera according to claim 1, characterized in that: The adjustment process of the focal plane bracket (1) on the three-dimensional precision adjustment frame (17) described in step eight is as follows: using the three-dimensional precision adjustment frame (17) to adjust the focal plane bracket (1) so that the coordinate system of the reference cubic mirror is parallel to the coordinate system of the splicing instrument (18) with an error of no more than 5″, and then using theodolite to assist in measurement, adjusting the focal plane bracket (1) to rotate by an angle θ along the long axis direction of the splicing instrument (18), while keeping the other two-dimensional angles unchanged, so that the splicing instrument (18) can observe the complete target surface of the detector and does not interfere with the focal plane bracket (1) in space.

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

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