A method for assembling and adjusting a satellite-borne limb detection payload

Abstract

The present invention discloses a method for assembling a satellite-borne limb detection payload. The main steps of the method include: 1. using a three-coordinate measuring instrument to complete the pre-assembly of the off-axis three-mirror telescope module; 2. establishing a whole system assembly benchmark, building a front optical system assembly optical path, using the imaging spot size and shape as criteria to complete the assembly and detection of each module of the front optical system; 3. establishing a whole machine joint adjustment optical path, completing the joint adjustment and testing of the front optical system and the spectral imaging system. This method is used to complete the high-precision assembly and adjustment of the satellite-borne limb detection payload, solving the problems in the prior art that the laser interferometer assembly method cannot determine the imaging focus and the lack of a whole system assembly method for the limb detection payload. This method simplifies the assembly and adjustment process and saves assembly and adjustment costs on the basis of ensuring the assembly and adjustment accuracy, and is suitable for the assembly and adjustment of semi-enclosed and compact space optical and mechanical systems.

Description

Technical Field

[0001] The present invention belongs to the field of assembly and adjustment of space optical mechanical systems, and in particular relates to an assembly and adjustment method for a satellite-borne limb detection payload. Background Art

[0002] The satellite-borne limb sounding payload can perform slice-type detection of the atmosphere along the tangent direction of the Earth. It obtains the spectral information of the scattered / radiated vertical structure of the atmosphere by rotating the scanning mirror, and uses the differential absorption spectroscopy technique to invert the distribution of atmospheric trace gases in the vertical space. The limb sounding payload is a space precision optical instrument and is divided into a front optical system and a spectral imaging system. Figure 1 As shown, the front optical system consists of a scanning mirror module 1, a depolarizer module 2, an off-axis three-mirror telescope module 3, and a color separator module 4. The scanning mirror module 1 is responsible for transmitting scattered / radiated light tangentially to the Earth's atmosphere to the depolarizer module 2 for depolarization at a specific scanning angle (different scanning angles correspond to different tangent heights of the Earth's atmosphere). The light is then focused by the off-axis three-mirror telescope module 3 and split by the color separator module 4, forming three independent spectral channels that are transmitted to the spectral imaging system. The spectral imaging system includes three Offner-Littrow imaging spectrometer modules (first spectrometer module 5, second spectrometer module 6, and third spectrometer module 7) with wavelengths of (290-380) nm, (375-480) nm, and (520-610) nm. These modules are responsible for decomposing the received optical signals into spectral information. Due to the differences between theoretical design and actual production and assembly, to achieve the high-precision specifications required for the payload, a series of assembly and adjustment methods are required after the design and production of each component to ensure that the limb detection payload meets the design specifications.

[0003] The mainstream method for aligning off-axis three-mirror optical systems currently uses computer-assisted alignment using a laser interferometer. This instrument emits a laser beam from near the focal point of the optical system under test. The beam passes through the optical system and a plane reflector, forming a return path that interferes with the measurement path, producing interference fringes. Based on the real-time alignment results, the position of the optical components is directly adjusted or the misalignment of the optical components is calculated, completing the alignment of the optical system.

[0004] The method of using laser interferometer for adjustment makes it difficult to determine whether the spatial position of the imaging focus of the front optical system matches that of the subsequent spectral imaging system. After each debugging is completed, the spectral imaging system must be connected for debugging. The procedure is repetitive, cumbersome, and time-consuming. In addition, during the development of the satellite-borne limb detection payload, there is currently a lack of suitable adjustment methods for the entire system adjustment of the front optical system and spectral imaging system. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a method for assembling and adjusting a satellite-borne limb detection payload, which solves the problems in the prior art that the laser interferometer assembly method cannot determine the imaging focus and lacks an assembly and adjustment method for the entire limb detection payload system. While ensuring the assembly and adjustment accuracy, the present invention simplifies the assembly and adjustment process and is suitable for the assembly and adjustment of semi-enclosed and compact space optical-mechanical systems.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A method for assembling and adjusting a satellite-borne limb detection payload comprises the following steps:

[0008] Step 1: Pre-assembly of the off-axis three-mirror telescope module: Use the off-axis three-mirror secondary mirror group of the off-axis three-mirror telescope module as the assembly reference of the off-axis three-mirror telescope module, and use a three-coordinate measuring machine to locate the off-axis three-mirror primary mirror group and the off-axis three-mirror third mirror group;

[0009] Step 2: Adjust the front optical system: Use the registration prism as the reference for the whole machine adjustment. Adjust the scanning mirror module, off-axis three-mirror telescope module, depolarizer module, and color separation filter module to the whole machine chassis. Use the size and shape of the imaging spot as the criterion. Connect the spectral imaging system to perform adjustment test on the front optical system.

[0010] Step 3: Joint debugging of the whole machine: Build the optical path for debugging the whole machine and complete the joint debugging and testing of the front optical system and spectral imaging system.

[0011] Furthermore, the step 1 includes:

[0012] Step 1.1: Use the off-axis three-mirror secondary mirror assembly as the debugging reference for the off-axis three-mirror telescope module. After fixing it to the off-axis three-mirror frame, no further adjustments are required.

[0013] Step 1.2: Assemble the ball head block and fine-tuning screws for the off-axis three-mirror primary mirror group and the off-axis three-mirror three-mirror group to adjust the degrees of freedom of the off-axis three-mirror primary mirror group and the off-axis three-mirror three-mirror group;

[0014] Step 1.3: Connect the off-axis three-mirror primary mirror group and the off-axis three-mirror third mirror group to the off-axis three-mirror frame respectively;

[0015] Step 1.4: Use a three-coordinate measuring machine to check the perpendicularity between the off-axis three-mirror secondary mirror assembly and the bottom surface of the off-axis three-mirror frame to ensure that it meets the accuracy requirements;

[0016] Step 1.5: Measure the vertical distances between the off-axis three-mirror primary mirror group, the off-axis three-mirror third mirror group, and the off-axis three-mirror secondary mirror group in sequence, ensuring that the planes of the off-axis three-mirror primary mirror group, the back of the off-axis three-mirror third mirror group, and the back of the off-axis three-mirror secondary mirror group are parallel to each other and perpendicular to the bottom surface of the off-axis three-mirror frame;

[0017] Step 1.6: Measure the parallelism of the off-axis three-mirror primary mirror group, the off-axis three-mirror third mirror group, and the off-axis three-mirror secondary mirror group in sequence;

[0018] Step 1.7: Measure the verticality of the off-axis three-mirror primary mirror assembly, the off-axis three-mirror third mirror assembly, and the bottom of the off-axis three-mirror frame in sequence;

[0019] Step 1.8: Whether the measured vertical distance, parallelism, and perpendicularity meet the preset requirements is used as a criterion. If not, adjust the distance and tilt angle between the off-axis three-mirror primary mirror group, the off-axis three-mirror third mirror group, and the off-axis three-mirror frame mounting surface by adjusting the fine-tuning screws of the off-axis three-mirror primary mirror group and the off-axis three-mirror third mirror group. Repeat steps 1.5 to 1.7 until all requirements are met.

[0020] Furthermore, the step 2 includes:

[0021] Step 2.1: Install the alignment prism to the top surface of the chassis mounting surface and the cubic prism to the side positioning boss of the chassis mounting surface. Align the first theodolite with the cubic prism. Place the second theodolite in the same direction as the first, at a height that ensures that the alignment prism can be observed. Place the third theodolite perpendicular to the second theodolite. Adjust the alignment prism installation position to achieve the uniformity of the optical and mechanical datums of the entire system.

[0022] Step 2.2: Using the registration prism as a reference, install the scanning mirror module into the entire chassis. Fine-tune the mechanical mounting position of the scanning mirror module until the crosshairs inside the fourth theodolite coincide with the return image of the scanning mirror module. Secure the scanning mirror module.

[0023] Step 2.3: Using the scanning mirror module as a reference, transfer the optical axis and install the off-axis three-mirror telescope module, depolarizer module, and color separation filter module into the entire chassis.

[0024] Step 2.4: Set up the debugging optical path and adjust the spatial position of the off-axis three-mirror telescope module and the color separation filter module until the imaging focus quality meets the requirements. Once the requirements are met, lock and fix the debugging devices and tooling in the box.

[0025] Step 2.5: Install the spectral imaging system and coordinate it with the front optical system. Return the scanning mirror module to zero. Install the first, second, and third spectrometer modules into the entire chassis in sequence. Connect them to the PI six-dimensional translation stage through tooling. Adjust the three degrees of freedom of each spectrometer module in the X and Y axis directions and the three degrees of freedom of rotation around the Z axis until a spectral image appears and the spectral signal intensity reaches the maximum value. After all three spectrometer modules meet the index requirements, fix the components of the front optical system.

[0026] Furthermore, the step 3 includes:

[0027] Step 3.1: After the scanning mirror module is powered on, it returns to zero and rotates to angle θ2. The scanning mirror module at this point is considered the reference for the incident light axis. The fifth theodolite aligns the scanning mirror module. A two-dimensional reflector is placed between the fifth theodolite and the scanning mirror module and adjusted to align with the fifth theodolite. The second, third, and fourth collimators are set up in the optical path after the fifth theodolite and secured.

[0028] Step 3.2: Install the third spectrometer module to the entire chassis and install the dial indicator so that the indicator needle is perpendicular to the slit of the third spectrometer module; light the second collimator separately and use the PI six-dimensional translation stage to adjust the third spectrometer module until the spatial resolution is less than the preset value and the spectral signal intensity is maximum, and record the dial indicator reading X2; light the third collimator separately and adjust the third spectrometer module until the spatial resolution is less than the preset value and the spectral signal intensity is maximum, and record the dial indicator reading X3 at this time; light the fourth collimator separately and adjust the third spectrometer module until the spatial resolution is less than the preset value and the spectral signal intensity is maximum, and record the dial indicator reading X4. The deflection adjustment value of the slit of the third spectrometer module is ΔX = X4-X2 = X3-X2;

[0029] Step 3.3: Adjust the slit of the third spectrometer module and light up the second, third, and fourth collimators simultaneously for debugging. Use the PI six-dimensional translation stage to debug the third spectrometer module until the spatial resolution is less than the preset value and the spectral signal intensity is maximized.

[0030] Step 3.4: Follow the methods in Steps 3.2 and 3.3 to install and adjust the first and second spectrometer modules in the entire chassis. After the adjustments are completed, light up the three sets of parallel light tube light sources at the same time to confirm that the spectral images of the first, second, and third spectrometer modules are simultaneously brightest and the spatial resolution is less than the preset value.

[0031] The beneficial effects of the present invention are:

[0032] 1. The present invention divides the complex optical-mechanical system into independent modules for assembly and adjustment, and utilizes devices such as theodolite, collimator, reflector, and assembly fixtures to unify and transfer the optical and mechanical datums, thereby ensuring assembly and adjustment accuracy while reducing the complexity of the entire system assembly and adjustment.

[0033] 2. The off-axis three-mirror telescope module is pre-assembled using a three-coordinate measuring instrument, and the scanning mirror module and the off-axis three-mirror telescope module are adjusted using theodolite, reflector and other devices; the front optical system is adjusted using a collimator, pinhole mount, two-dimensional turntable, fine-tuning screw and other devices, solving the problem that the laser interferometer adjustment method cannot determine the imaging focus position of the front optical system.

[0034] 3. Use the theodolite, collimator, two-dimensional turntable, and assembly tooling to build the whole machine debugging optical path, and use the PI six-dimensional translation stage and micrometer to complete the whole machine system assembly and adjustment to ensure that the spatial resolution within the field of view meets the index requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of an optical system for edge detection payload in the prior art;

[0036] Figure 2 This is a schematic diagram of the off-axis three-mirror telescope module structure of the present invention;

[0037] Figure 3 A schematic diagram of a ball head block according to the present invention;

[0038] Figure 4 This is a schematic diagram of the alignment prism adjustment of the present invention;

[0039] Figure 5 Schematic diagram of the front optical system of the present invention;

[0040] Figure 6 This is a schematic diagram of the front optical system assembly of the present invention;

[0041] Figure 7 This is a schematic diagram of the assembly and adjustment of the satellite-borne limb detection payload of the present invention.

[0042] Reference numerals:

[0043] 1. Scanning mirror module; 101. First collimator; 102. Second collimator; 103. Third collimator; 104. Fourth collimator; 105. First pinhole mount; 106. Second pinhole mount; 107. Third pinhole mount; 108. Plane reflector; 109. Two-dimensional reflector; 110. Scale microscope; 2. Depolarizer module; 3. Off-axis three-mirror telescope module; 301. Off-axis three-mirror primary mirror group; 302. Off-axis three-mirror secondary mirror group; 303. Off-axis three-mirror third mirror group; 304. Off-axis three-mirror frame; 305. Off-axis three-mirror field stop; 306, ball head block; 4, color separation film module; 401, first color separation film group; 402, second color separation film group; 5, first spectrometer module; 501, first imaging focus; 6, second spectrometer module; 601, second imaging focus; 7, third spectrometer module; 701, third imaging focus; 801, registration prism; 802, cubic prism; 803, first theodolite; 804, second theodolite; 805, third theodolite; 806, fourth theodolite; 807, fifth theodolite; 9, entire chassis; 901, entrance aperture; 10, combined turntable. DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to the accompanying drawings and examples.

[0045] The present invention provides a method for assembling and adjusting a satellite-borne limb detection payload, which mainly includes the following steps:

[0046] Step 1: Pre-assembly of the off-axis three-mirror telescope module 3:

[0047] Step 1.1: If Figure 2-Figure 3 As shown, the off-axis three-mirror secondary mirror group 302 is used as the debugging reference of the off-axis three-mirror telescope module 3, and no adjustment is required after it is fixed; the off-axis three-mirror secondary mirror group 302 is installed on the off-axis three-mirror frame 304 and fixed, and the installation position is a clearance fit with a tolerance of 0.02mm. The installation contact surface between the off-axis three-mirror secondary mirror group 302 and the off-axis three-mirror frame 304 is a polished surface, which jointly ensures the installation accuracy; the off-axis three-mirror secondary mirror group 302 is a spherical mirror.

[0048] Step 1.2: Assemble two ball head blocks 306 around the off-axis three-mirror primary mirror assembly 301, and two ball head blocks 306 on the upper, lower, and right sides of the off-axis three-mirror three-mirror assembly 303. Install and secure four fine-tuning screws on the back of the off-axis three-mirror primary mirror assembly 301 and the off-axis three-mirror three-mirror assembly 303. The ball head blocks 306 and fine-tuning screws can be used to adjust the degrees of freedom of the off-axis three-mirror primary mirror assembly 301 and the off-axis three-mirror three-mirror assembly 303 in six directions.

[0049] Step 1.3: Connect the off-axis three-mirror primary mirror assembly 301 and the off-axis three-mirror third mirror assembly 303 to the off-axis three-mirror frame 304 respectively. Unscrew the fine-tuning screws 2mm from each screw (this adjustment amount is reserved in the design, and the washers will be adjusted later based on the measured value). Tighten the mounting screws until the screws contact the side walls of the off-axis three-mirror frame 304. Keep the mounting screws adjustable and fixed so that the fine-tuning screws have a certain amount of adjustment.

[0050] Step 1.4: Fix the assembled off-axis three-mirror telescope module 3 on a marble platform and use a three-coordinate measuring machine to check the verticality of the off-axis three-mirror secondary mirror group 302 and the bottom surface of the off-axis three-mirror frame 304 to confirm that the error is within 0.015.

[0051] Step 1.5: Measure the vertical distances between the off-axis three-mirror primary mirror assembly 301, the off-axis three-mirror third mirror assembly 303, and the off-axis three-mirror secondary mirror assembly 302 in sequence to ensure their basic dimensional relationship (within 0.03 mm). The backs of the off-axis three-mirror primary mirror assembly 301, the off-axis three-mirror third mirror assembly 303, and the back of the off-axis three-mirror secondary mirror assembly 302 are parallel to each other and perpendicular to the bottom surface of the off-axis three-mirror frame 304.

[0052] Step 1.6: Measure the parallelism of the off-axis three-mirror primary mirror group 301, the off-axis three-mirror third mirror group 303, and the off-axis three-mirror secondary mirror group 302 in sequence, and the parallelism must be within 0.03.

[0053] Step 1.7: Measure the perpendicularity between the off-axis three-mirror primary mirror group 301, the off-axis three-mirror third mirror group 303, and the bottom of the off-axis three-mirror frame 304 in sequence. The perpendicularity must be within 0.03.

[0054] Step 1.8: Use the vertical distance, parallelism, and perpendicularity measured above as criteria. If the requirements are not met, adjust the distance and tilt angle between the off-axis three-mirror primary mirror group 301, the off-axis three-mirror third mirror group 303, and the mounting surface of the off-axis three-mirror frame 304 by adjusting the fine-tuning screws on the back of the off-axis three-mirror primary mirror group 301 and the off-axis three-mirror third mirror group 303. Repeat steps 1.5 to 1.7 until all requirements are met. The pre-assembly of the off-axis three-mirror telescope module 3 is now completed.

[0055] Step 2: Adjust the front optical system:

[0056] Step 2.1: If Figure 4 As shown, install the alignment prism 801 to transfer the optical and mechanical reference of the whole machine. Place the whole machine case 9 with the mounting surface facing downward on a marble platform. Install the alignment prism 801 to the other top surface of the whole machine case 9 away from the mounting surface of the whole machine case 9, and clamp the cubic prism 802 to the side positioning boss of the mounting surface of the whole machine case 9 (finely processed, with a perpendicularity of 0.005 to the mounting surface of the whole machine). Align the first theodolite 803 with the cubic prism 802, observe the crosshair return image of the cubic prism 802 through the eyepiece, and adjust it to coincide with the crosshairs of the eyepiece of the first theodolite 803. Lead the side positioning surface reference of the whole machine case 9 to the first theodolite 803; set the horizontal angle of the first theodolite 803 to zero; place the second theodolite 804 in the same direction as the first theodolite 803, and at a height that ensures that the alignment prism 801 can be observed.

[0057] Next, aim the first theodolite 803 and the second theodolite 804 at each other until their eyepiece crosshairs overlap. Record the horizontal angle α1 of the first theodolite 803. Set the horizontal angle of the second theodolite 804 to zero and then rotate it 180° - α1 to point toward the registration prism 801. Position the third theodolite 805 perpendicular to the second theodolite 804. Set the elevation angle of the third theodolite 805 to a fixed 90° angle, pointing toward the registration prism 801. Observe the image of the registration prism 801 reflected by the crosshairs in the eyepieces of the second and third theodolites 804 and 805, respectively. Adjust the mounting position of the registration prism 801 until the crosshairs within the second and third theodolites 804 and 805 overlap with the image reflected by the registration prism 801 (with a deviation of no more than 10%). Secure the registration prism 801.

[0058] The deviation angle data of the return images of the second and third theodolites 804 and 805 are recorded. Then, the second and third theodolites 804 and 805 are aligned with the eyepiece crosshairs to obtain the offset angles δ23 and δ32 of the two theodolites. This completes the installation of the alignment prism 801 and the unification of the optical and mechanical datums of the entire machine.

[0059] Step 2.2: Combine Figure 5-Figure 6 Using the alignment prism 801 as a reference, install the scanning mirror module 1 into the complete chassis 9. Mount the complete chassis 9 onto the optical platform using the fixture. Adjust the fourth theodolite 806 to a 90° angle and align the alignment prism 801. Use the fixture to level the complete chassis 9, ensuring that the image returned by the alignment prism 801 coincides with the eyepiece crosshairs of the fourth theodolite 806. Secure the complete chassis 9. Rotate the fourth theodolite 806 horizontally by angle θ1 (the angle between the incident optical axis and the normal of the alignment prism 8) to point it toward the entrance aperture 901. Install the scanning mirror module 1 into the complete chassis 9, maintaining an adjustable position.

[0060] After the scanning mirror module 1 is powered on and returns to zero, it rotates by an angle θ2 (the angle between the incident light axis and the zero-position normal of the scanning mirror module 1). At this point, the scanning mirror module 1 should be perpendicular to the incident light axis. Fine-tune the mechanical installation position of the scanning mirror module 1 while observing the crosshair return image of the eyepiece of the fourth theodolite 806 until the crosshairs inside the fourth theodolite 806 coincide with the return image of the scanning mirror module 1 (the deviation is required to be ≤10″). Then, secure the scanning mirror module 1.

[0061] Step 2.3: Using the scanning mirror module 1 as a reference for the optical axis, install the off-axis three-mirror telescope module 3 into the complete chassis 9. Install the pre-assembled off-axis three-mirror telescope module 3 into the complete chassis 9. After powering on the scanning mirror module 1, return it to zero and rotate it to an angle θ2 (the angle between the incident optical axis and the zero-position normal of the scanning mirror module 1). Consider the scanning mirror module 1 at this point as the reference for the incident optical axis. Install the first collimator 101 onto the combined turntable 10 (consisting of a lift and a motorized two-dimensional turntable). Adjust the lift until the center height of the first collimator 101 is the same as the center height of the front optical system. Replace the eyepiece assembly of the first collimator 101 with a crosshair. After illuminating the light source, adjust the position of the first collimator 101 using the motorized two-dimensional turntable so that it is aligned with the scanning mirror module 1. Secure the first collimator 101. Return the angle of the scanning mirror module 1 to zero. After the incident light passes through the entrance aperture 901 and is reflected by the scanning mirror module 1, it should enter the off-axis three-mirror field aperture 305 perpendicularly. Temporarily secure the plane mirror 108 at the off-axis three-mirror field stop 305, adjust the overall position of the off-axis three-mirror telescope module 3 until the eyepiece crosshairs of the first collimator 101 coincide with the return image of the plane mirror 108 at the off-axis three-mirror field stop 305, secure the off-axis three-mirror telescope module 3, and remove the plane mirror 108. The depolarizer module 2, color separation filter module 4, first pinhole holder 105, second pinhole holder 106, and third pinhole holder 107 (three pinhole holders are separately designed debugging fixtures to assist in assembly and adjustment, used to confirm the positions of the three imaging focal points (501, 601, 701) of the front optical system) are then sequentially installed into the entire chassis 9 according to the hole positions. This completes the positioning and installation of the modules of the front optical system using the alignment prism 801 as a reference.

[0062] Step 2.4: Combine Figure 6 Build and debug the optical path and adjust the off-axis three-mirror telescope module 3. Replace the eyepiece crosshairs of the first collimator 101 with a star point aperture (100μm). Place a UV-visible LED light source and a diffuse transmission plate in front of the eyepiece of the first collimator 101. Rotate the scanning mirror module 1 to the zero position. After illuminating the light source, observe the third imaging focal point 701 focused on the third pinhole holder 107 by the off-axis three-mirror telescope module 3. It should be near the pinhole of the third pinhole holder 107. If the difference is large, first adjust the position of the third pinhole holder 107 until the third imaging focal point 701 is near the pinhole of the third pinhole holder 107.

[0063] The positions and deflection angles of the off-axis three-mirror primary mirror assembly 301 and the off-axis three-mirror third mirror assembly 303 are adjusted by adjusting the fine-tuning screws until the third imaging focus 701 can pass through the pinhole of the third pinhole holder 107. The third imaging focus 701 passing through the pinhole of the third pinhole holder 107 is observed using a scale microscope 110. The third imaging focus 701 should be a perfect circle in the meridian and sagittal directions, with a diameter less than 65 μm. Observe whether the third imaging focus 701 meets these requirements. If not, adjust the positions of the fine-tuning screws and the third pinhole holder 107 until the third imaging focus 701 passing through the pinhole of the third pinhole holder 107 meets these requirements.

[0064] Adjust the positions of the first color separation plate group 401, the second color separation plate group 402, and the first and second pinhole seats 105 and 106 respectively until the first imaging focus 501 and the second imaging focus 601 can pass through the small holes on the corresponding first and second pinhole seats 105 and 106, and meet the requirements that the first imaging focus 501 and the second imaging focus 601 should be a perfect circle in the meridian and sagittal directions and have a diameter of less than 65μm.

[0065] Symmetrically tighten the mounting screws of the off-axis three-mirror primary mirror group 301 and the off-axis three-mirror three-mirror group 303, and observe whether the first imaging focus 501, the second imaging focus 601, and the third imaging focus 701 change. If so, readjust them until the requirements are met, then tighten and remove all debugging devices and tooling in the box.

[0066] Step 2.5: Install the spectral imaging system and verify that the imaging quality of the front optical system meets the requirements. Return the scanning mirror module 1 to zero. Install the first, second, and third spectrometer modules 5, 6, and 7 sequentially into the complete system chassis 9. Connect them to the PI six-dimensional translation stage via tooling. Adjust the three degrees of freedom of each spectrometer module individually: translation in the X and Y axes, and rotation about the Z axis, until a spectral image is generated. The spatial resolution of the spectrometer must be less than 5 pixels (13 μm per pixel) and the spectral signal intensity reaches maximum value. After all three spectrometer modules meet the requirements, remove the off-axis three-mirror telescope module 3. Use a coordinate measuring machine to measure the eight gaps between the off-axis three-mirror primary mirror assembly 301, the off-axis three-mirror third mirror assembly 303, and the mounting surface of the off-axis three-mirror frame 304. Install washers of the appropriate thickness and replace the fine-tuning screws. Repeat steps 2.3 to 2.5 to confirm that the off-axis three-mirror telescope module 3 is in the same state as before replacing the gasket. Otherwise, continue to repair the gasket until the above requirements are met. Then reinstall the entire chassis 9. After confirming that it meets the indicators, fix the components of the front optical system. At this point, the front optical system assembly is completed.

[0067] Step 3: Assembly and adjustment of the whole system:

[0068] The total field of view of the edge detection payload is ±2.5°. The consistency of the response at each angle within the field of view must be ensured through debugging. For the whole machine joint debugging, the debugging steps of the first spectrometer module 5, the second spectrometer module 6, and the third spectrometer module 7 are similar. Here, the third spectrometer module 7 is taken as an example. Figure 7 As shown, three sets of collimators (second collimator 102, third collimator 103, and fourth collimator 104) are installed, emitting three beams of collimated light at 0° and ±2.5°, respectively. After being transmitted through the pre-optical system, these beams are focused onto the top, middle, and bottom focal points of the third spectrometer slit. Ideally, the three focal points of the collimated light emitted by the three sets of collimators, after being focused by the pre-optical system, should be collinear and perfectly aligned with the third spectrometer slit, with the two completely overlapping. During actual alignment, the line connecting the image points after being focused by the pre-optical system and the third spectrometer slit will deflect to some extent. This alignment is achieved by deflecting the third spectrometer slit.

[0069] Step 3.1: Combine Figure 7After power is applied, scanning mirror module 1 returns to zero and rotates to an angle θ2 (the angle between the incident light axis and the zero-position normal of scanning mirror module 1). This angle serves as the incident light axis reference. The fifth theodolite 807 aligns scanning mirror module 1, recording its elevation and azimuth angles. A two-dimensional reflector 109 (with an aperture larger than the total aperture of the system) is placed between the fifth theodolite 807 and scanning mirror module 1 and adjusted to align with the fifth theodolite 807. The reference of scanning mirror module 1 is transferred to two-dimensional reflector 109. Using two-dimensional reflector 109 as a reference, the positions of the three collimators are adjusted.

[0070] Set up the second collimator 102 on the optical platform, replace the eyepiece with a crosshair, collimate the two-dimensional reflector 109, and secure the second collimator 102. Set up the third collimator 103. While keeping the horizontal angle of the fifth theodolite 807 unchanged, adjust the pitch angle by +2.5°. Adjust the two-dimensional reflector 109 until it is aligned with the fifth theodolite 807. Based on this, adjust the third collimator 103 and the two-dimensional reflector 109 to align them, and secure the third collimator 103. Similarly, adjust the fifth theodolite 807 and the two-dimensional reflector 109 by 2.5°. Collimate the fourth collimator 104 and secure it.

[0071] Step 3.2: Install the third spectrometer module 7 into the chassis 9 and install the dial indicator, aligning the indicator needle perpendicular to the slit of the third spectrometer module 7. Replace the eyepiece assemblies of the second, third, and fourth collimators 102, 103, and 104 with star-point apertures (100 μm). Place the UV-visible LED light source assembly and diffuse transmission plate. Light the second collimator 102 alone. Use the PI six-dimensional translation stage to adjust the third spectrometer module 7 to a spatial resolution of less than 5 pixels and maximum spectral signal intensity. Record the dial indicator reading X2. Light the third collimator 103 alone and adjust the third spectrometer module 7 to a spatial resolution of less than 5 pixels and maximum spectral signal intensity. Record the dial indicator reading X3. Light the fourth collimator 104 alone and adjust the third spectrometer module 7 to a spatial resolution of less than 5 pixels and maximum spectral signal intensity. Record the dial indicator reading X4. The formula ΔX=X4-X2=X3-X2 should be obtained, where ΔX is the deflection adjustment value of the slit of the third spectrometer module 7.

[0072] Step 3.3: Remove the third spectrometer module 7 and illuminate the slit of the third spectrometer module 7 using a mercury lamp and a diffuse transmission plate. Based on the number of pixel columns T corresponding to a characteristic peak of the mercury lamp on the CCD detector, ΔX / 13 (single pixel size) = the number of pixel columns ΔT to be deflected. After adjusting the slit of the third spectrometer module 7, reinsert it into the entire device and simultaneously illuminate the second, third, and fourth collimators 102, 103, and 104 for adjustment. Using the PI six-dimensional translation stage, adjust the third spectrometer module 7 to a spatial resolution of less than 5 pixels and maximum spectral signal intensity.

[0073] Step 3.4: Follow the methods of steps 3.2 and 3.3 to sequentially adjust the first spectrometer module 5 and the second spectrometer module 6 in the entire machine housing 9. After the adjustment is completed, light up the three sets of parallel light tube light sources at the same time to confirm that the spectral images of the first spectrometer module 5, the second spectrometer module 6, and the third spectrometer module 7 reach the brightest at the same time and the spatial resolution is less than 5 pixels. The whole machine adjustment work is completed.

[0074] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for assembling and adjusting a satellite-borne limb detection payload, characterized in that: The method comprises the following steps: Step 1: Pre-assembly of the off-axis three-mirror telescope module: Use the off-axis three-mirror secondary mirror group of the off-axis three-mirror telescope module as the assembly reference of the off-axis three-mirror telescope module, and use a three-coordinate measuring machine to locate the off-axis three-mirror primary mirror group and the off-axis three-mirror third mirror group; Step 2: Adjust the front optical system: Use the registration prism as the reference for the whole machine adjustment. Adjust the scanning mirror module, off-axis three-mirror telescope module, depolarizer module, and color separation filter module to the whole machine chassis. Use the size and shape of the imaging spot as the criterion. Connect the spectral imaging system to perform adjustment test on the front optical system. Step 3: Joint debugging of the whole machine: Build the optical path for debugging the whole machine and complete the joint debugging and testing of the front optical system and spectral imaging system.

2. The method for assembling and adjusting a satellite-borne limb detection payload according to claim 1, characterized in that: The step 1 comprises: Step 1.1: Use the off-axis three-mirror secondary mirror assembly as the debugging reference for the off-axis three-mirror telescope module. After fixing it to the off-axis three-mirror frame, no further adjustments are required. Step 1.2: Assemble the ball head block and fine-tuning screws for the off-axis three-mirror primary mirror group and the off-axis three-mirror three-mirror group to adjust the degrees of freedom of the off-axis three-mirror primary mirror group and the off-axis three-mirror three-mirror group; Step 1.3: Connect the off-axis three-mirror primary mirror group and the off-axis three-mirror third mirror group to the off-axis three-mirror frame respectively; Step 1.4: Use a three-coordinate measuring machine to check the perpendicularity between the off-axis three-mirror secondary mirror assembly and the bottom surface of the off-axis three-mirror frame to ensure that it meets the accuracy requirements; Step 1.5: Measure the vertical distances between the off-axis three-mirror primary mirror group, the off-axis three-mirror third mirror group, and the off-axis three-mirror secondary mirror group in sequence, ensuring that the planes of the off-axis three-mirror primary mirror group, the back of the off-axis three-mirror third mirror group, and the back of the off-axis three-mirror secondary mirror group are parallel to each other and perpendicular to the bottom surface of the off-axis three-mirror frame; Step 1.6: Measure the parallelism of the off-axis three-mirror primary mirror group, the off-axis three-mirror third mirror group, and the off-axis three-mirror secondary mirror group in sequence; Step 1.7: Measure the verticality of the off-axis three-mirror primary mirror assembly, the off-axis three-mirror third mirror assembly, and the bottom of the off-axis three-mirror frame in sequence; Step 1.8: Whether the measured vertical distance, parallelism, and perpendicularity meet the preset requirements is used as a criterion. If not, adjust the distance and tilt angle between the off-axis three-mirror primary mirror group, the off-axis three-mirror third mirror group, and the off-axis three-mirror frame mounting surface by adjusting the fine-tuning screws of the off-axis three-mirror primary mirror group and the off-axis three-mirror third mirror group. Repeat steps 1.5 to 1.7 until all requirements are met.

3. The method for assembling and adjusting a satellite-borne limb detection payload according to claim 2, characterized in that: The step 2 includes: Step 2.1: Install the alignment prism to the top surface of the chassis mounting surface and the cubic prism to the side positioning boss of the chassis mounting surface. Align the first theodolite with the cubic prism. Place the second theodolite in the same direction as the first, at a height that ensures that the alignment prism can be observed. Place the third theodolite perpendicular to the second theodolite. Adjust the alignment prism installation position to achieve the uniformity of the optical and mechanical datums of the entire system. Step 2.2: Using the registration prism as a reference, install the scanning mirror module into the entire chassis. Fine-tune the mechanical mounting position of the scanning mirror module until the crosshairs inside the fourth theodolite coincide with the return image of the scanning mirror module. Secure the scanning mirror module. Step 2.3: Using the scanning mirror module as a reference, transfer the optical axis and install the off-axis three-mirror telescope module, depolarizer module, and color separation filter module into the entire chassis. Step 2.4: Set up the debugging optical path and adjust the spatial position of the off-axis three-mirror telescope module and the color separation filter module until the imaging focus quality meets the requirements. Once the requirements are met, lock and fix the debugging devices and tooling in the box. Step 2.5: Install the spectral imaging system and coordinate it with the front optical system. Return the scanning mirror module to zero. Install the first, second, and third spectrometer modules into the entire chassis in sequence. Connect them to the PI six-dimensional translation stage through tooling. Adjust the three degrees of freedom of each spectrometer module in the X and Y axis directions and the three degrees of freedom of rotation around the Z axis until a spectral image appears and the spectral signal intensity reaches the maximum value. After all three spectrometer modules meet the index requirements, fix the components of the front optical system.

4. The method for assembling and adjusting a satellite-borne limb detection payload according to claim 3, characterized in that: The step 3 comprises: Step 3.1: After the scanning mirror module is powered on, it returns to zero and rotates to angle θ2. The scanning mirror module at this point is considered the reference for the incident light axis. The fifth theodolite aligns the scanning mirror module. A two-dimensional reflector is placed between the fifth theodolite and the scanning mirror module and adjusted to align with the fifth theodolite. The second, third, and fourth collimators are set up in the optical path after the fifth theodolite and secured. Step 3.2: Install the third spectrometer module to the entire chassis and install the dial indicator so that the indicator needle is perpendicular to the slit of the third spectrometer module; light the second collimator separately and use the PI six-dimensional translation stage to adjust the third spectrometer module until the spatial resolution is less than the preset value and the spectral signal intensity is maximum, and record the dial indicator reading X2; light the third collimator separately and adjust the third spectrometer module until the spatial resolution is less than the preset value and the spectral signal intensity is maximum, and record the dial indicator reading X3 at this time; light the fourth collimator separately and adjust the third spectrometer module until the spatial resolution is less than the preset value and the spectral signal intensity is maximum, and record the dial indicator reading X4. The deflection adjustment value of the slit of the third spectrometer module is ΔX = X4-X2 = X3-X2; Step 3.3: Adjust the slit of the third spectrometer module and light up the second, third, and fourth collimators simultaneously for debugging. Use the PI six-dimensional translation stage to debug the third spectrometer module until the spatial resolution is less than the preset value and the spectral signal intensity is maximized. Step 3.4: Follow the methods in Steps 3.2 and 3.3 to install and adjust the first and second spectrometer modules in the entire chassis. After the adjustments are completed, light up the three sets of parallel light tube light sources at the same time to confirm that the spectral images of the first, second, and third spectrometer modules are simultaneously brightest and the spatial resolution is less than the preset value.

Images