A ground-based high-precision four-quadrant sun sensor and its calibration method

Abstract

The present invention proposes a ground-based high-precision four-quadrant solar sensor and a calibration method thereof. The present invention improves the signal-to-noise ratio received by the detector by designing the aperture size of the front aperture tube in the solar sensor and the extinction structure. The initial angle error of the detector is greatly reduced by a centering adjustment method and an outdoor calibration method. Through the above-mentioned design and method, the theoretical initial tracking error angle of the traditional ground-based four-quadrant solar sensor is reduced from 0.2° to 0.022°, and the angle sensitivity for solar radiation alignment tracking is as high as 0.003°. High-precision alignment tracking of solar radiation is achieved, solving the problems of high-precision tracking and miniaturization and lightness that urgently need to be solved in ground-based solar sensors.

Description

Technical Field

[0001] The present invention relates to the field of high-precision sun tracking, and in particular to a ground-based high-precision four-quadrant sun sensor and a calibration method thereof. Background Art

[0002] As the closest star to Earth, the Sun's radiation provides the vast majority of Earth's energy. While providing energy to Earth, solar radiation also profoundly influences the Earth's atmosphere, oceans, and landmasses. High-precision observations of solar radiation are currently a key research direction in fields such as atmospheric chemistry and dynamics, climate meteorology, and ocean dynamics. Achieving and maintaining an uncertainty of 0.05%-1% in absolute radiation measurements in the solar reflectance spectrum is essential for confirming the long-term cycles and trends of climate parameters.

[0003] High-precision irradiance observations in the solar reflectance spectrum require a high-precision sun tracking system. This system ensures that the entrance slit of the solar spectral irradiance meter is aligned with the sun. Tracking accuracy is closely related to irradiance measurements. To maintain an uncertainty of 0.05% for the solar spectral irradiance meter, the sun tracking accuracy must reach 0.1°, meaning the sun sensor accuracy must be better than 0.1°.

[0004] Currently, most sun sensors used in ground-based solar trackers, both domestically and internationally, do not meet the aforementioned accuracy requirements. Furthermore, those that do meet these requirements are often too large and have a narrow field of view. In light of this, the present invention proposes a high-precision, four-quadrant ground-based sun sensor and its calibration method, overcoming these issues in existing instruments. Summary of the Invention

[0005] In order to solve the problem proposed in the above background technology that high-precision absolute radiation measurement of the solar reflection spectrum requires a high-precision solar sensor with a large field of view, small size, and low power consumption, the present invention provides a ground-based high-precision four-quadrant solar sensor and a calibration method thereof, which is a ground-based solar sensor with a small size, low power consumption, and a large field of view and a calibration method thereof.

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

[0007] A ground-based high-precision four-quadrant solar sensor comprises a stray light elimination aperture tube A, a stray light elimination aperture tube B, a stray light elimination aperture tube C, a compression washer, a coarse aiming target, a front aperture tube, a four-quadrant photoelectric detector module, and a sensor base. The main structure of the ground-based high-precision four-quadrant solar sensor comprises a front aperture tube and a sensor base below it, which are connected by a threaded fit and fixed for centering by an assembly surface below the threaded fit. The first step of the sensor base is a threaded fit, and the second step is an assembly surface, which adopts a clearance fit. The stray light elimination aperture tubes A, B, and C inside the front aperture tube are fixed by tightening upwards through the inner wall threads of the compression washer. The coarse aiming target is connected to the screw hole of the front aperture tube by threads. The sensor base has a through hole and is connected to a solar observation instrument by screws. The axis of the coarse aiming circular hole on the front aperture tube coincides with the axis of the coarse aiming target.

[0008] Furthermore, the incident aperture of the front aperture is designed based on controlling the energy received by the detector; the radiation flux of the incident light is controlled based on the maximum response current of the detector, and the incident aperture size is then reversely deduced based on the size of the radiation flux of the incident light, the solar spectrum irradiance curve at the summer solstice in the Dunhuang area, and the spectral response efficiency curve of the detector.

[0009] Furthermore, the sun sensor has a field of view of approximately 15° and an overall length of 40-100 mm. Within the pre-aperture tube, stray light elimination tubes A, B, and C absorb diffuse background light from the sky.

[0010] Furthermore, the front aperture tube and the sensor base are fitted together through the clearance of the cylindrical assembly surface to complete the centering assembly; using a focus-adjustable microscope and a three-dimensional moving platform, the center deviation of the four-quadrant photosensitive surface center and the center of the mating surface is adjusted to within 0.005mm, so that the offset of the center position of the light spot and the center position of the photosensitive surface of the four-quadrant photoelectric detector of the four-quadrant photoelectric detector module is within 0.01mm, that is, the angle error of the sun sensor aligned with the sun is controlled within 0.012°.

[0011] Furthermore, the diameter of the coarse aiming circular hole is 0.5 mm to 2 mm, and the coarse aiming target is white polytetrafluoroethylene, on which a center position and a cross positioning mark are engraved.

[0012] The present invention also provides a calibration method for a ground-based high-precision four-quadrant sun sensor, comprising the following steps:

[0013] The first step is to select a sunny day with few clouds for the calibration experiment.

[0014] The second step is to fix the sensor base to the dual-axis automatic turntable through its reserved through-holes. By adjusting the elevation and azimuth of the dual-axis automatic turntable, align the sun spot falling through the coarse aiming hole in the front aperture tube with the center of the white polytetrafluoroethylene coarse aiming target, completing the coarse alignment of the solar sensor with the sun. At this point, the azimuth and elevation of the dual-axis automatic turntable are set as the starting tracking angles. According to the real-time solar trajectory calculated in the astronomical calendar, set the computer program to start automatic tracking.

[0015] Step 3: Remove the front aperture tube and replace it with stray light elimination aperture tube A, stray light elimination aperture tube B, and stray light elimination aperture tube C, each of which has an incident aperture larger than the diameter of the photosensitive surface of the four-quadrant photodetector module, and fix it to the sensor base through threads;

[0016] Step 4: During a cloud-free period, collect the response values ​​of the four channels of the four-quadrant photoelectric detector; each acquisition time is within 0.1s, and multiple groups of data are collected; the acquisition time points are equidistant and the acquisition time periods are symmetrical;

[0017] Step 5. After all data are collected, the channel values ​​of each group are averaged to obtain the response value of each channel. After deducting the ambient light noise of each channel, the response value of the first channel is used as the denominator and the values ​​of the other three channels are used as the numerator to obtain the deviation coefficient of each channel. Thus, the deviation coefficient of each channel under different light intensities is obtained, and the weighted average is taken to obtain the compensation coefficient of each channel.

[0018] Step 6: Input the compensation coefficient into the computer program. The addition of the compensation coefficient makes the four channels of the sun sensor produce the same response to the light source of the same irradiance, completing the calibration process of the consistency of the response of each channel of the sun sensor to uniform light.

[0019] Beneficial effects:

[0020] (1) The present invention has the advantages of small size, compact structure, light weight and low power consumption, and is convenient for installation and disassembly on related instruments that require sun tracking, and for transportation and carrying in field experimental sites.

[0021] (2) The present invention proposes an aperture design principle based on controlling the energy received by the detector, which controls the energy received by the detector to about 50% of the maximum response current, thereby improving the signal-to-noise ratio of the photoelectric detector and making the detector respond well to solar radiation.

[0022] (3) The present invention proposes a method for mechanical and instrument assembly of a four-quadrant solar sensor, which solves the problem of large centering errors between the solar radiation spot and the detector center. The initial deviation angle of 0.1°, which is common in ground-based solar sensors, is reduced to 0.012°. This improves the feedback of the solar sensor regarding the position of the solar radiation spot on the detector, thereby enhancing the solar tracking accuracy of the ground-based solar sensor.

[0023] (4) This invention proposes an outdoor calibration method for a four-quadrant solar sensor, which solves the problem of reduced accuracy in solar radiation spot position feedback due to channel consistency differences in the four-quadrant photoelectric detector. The consistency differences in the four channels of the four-quadrant photoelectric sensor are reduced from 1-2% to below 0.2%, that is, the initial error of the detector angle is reduced from 0.1° to 0.01°. This improves the electronic response accuracy of the four-quadrant solar sensor.

[0024] (5) Through the above method, the present invention reduces the theoretical initial tracking error angle of the traditional ground four-quadrant solar sensor from 0.2° to 0.022°, and the angular sensitivity to solar radiation changes is as high as 0.003°, achieving high-precision alignment tracking of solar radiation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the overall structure of the ground-based high-precision four-quadrant sun sensor of the present invention;

[0026] Figure 2 This is a schematic diagram of the principle of locating the center of the light spot of the four-quadrant detector of the present invention;

[0027] Figure 3 Schematic diagram of the method for aligning the center of the four-quadrant detector with the center of the sensor base of the present invention;

[0028] Figure 4 A flowchart of the steps of the calibration process in the present invention;

[0029] Figure 5 This is a diagram of the device layout for the calibration process in the present invention. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0031] The high-precision four-quadrant ground-based sun sensor of the present invention can assist solar radiation measurement instruments in high-precision sun tracking. It also offers advantages such as small size, lightweight, wide field of view, and low power consumption. Furthermore, the present invention proposes a method for calibrating the response consistency of different channels of the sun sensor.

[0032] like Figure 1 As shown in FIG, the structure of the ground-based high-precision four-quadrant sun sensor of the present invention includes a stray light diaphragm cylinder A1, a stray light diaphragm cylinder B2, a stray light diaphragm cylinder C3, a compression washer 4, a coarse aiming target 5, a pre-diaphragm cylinder 6, a four-quadrant photoelectric detector module 7, and a sensor base 8. It should be understood that the stray light diaphragm cylinder A1, the stray light diaphragm cylinder B2, and the stray light diaphragm cylinder C3 are three levels in total, and can also be two or more levels. Figure 1 As shown, the main structure of the ground-based high-precision four-quadrant sun sensor of the present invention consists primarily of a pre-aperture tube 6 and a sensor base 8 below. These two are connected by a threaded fit, with the mounting surface below the threads providing centering and fixation. The sensor base 8 has a threaded first step and a mounting surface on the second step. The mounting surfaces utilize a clearance fit with a radial clearance of 0.02 mm, ensuring that the rotational center of the sensor base 8's mounting surface and the pre-aperture tube 6 are within 0.01 mm of each other. Within the pre-aperture tube 6, the stray light suppression tubes A1, B2, and C3 are secured from bottom to top by a compression washer 4 screwed upward through the inner wall threads. The coarse aiming target 5 is threaded into a threaded hole in the pre-aperture tube 6. The four-quadrant detector module 7 is composed of four-quadrant photodetector pins soldered to a circular circuit board. The pins are then secured to a sensor base 8 through four holes in the circular circuit board using screws, spring washers, and flat washers. The sensor base 8 has through-holes for screw connection to a solar observation instrument requiring sun tracking.

[0033] During the outdoor sun tracking process, the working process of the ground-based high-precision four-quadrant sun sensor of the present invention is as follows:

[0034] During outdoor sun tracking, the dual-axis automatic turntable is manually adjusted or computer-controlled to align the coarse aiming hole of the pre-aperture tube 6 with the center of the coarse aiming target 5, preferably made of white polytetrafluoroethylene, on the pre-aperture tube 6. The sun sensor is now roughly aligned with the sun. Solar radiation then enters the entrance hole of the pre-aperture tube 6, passes through the stray light elimination tubes A1, B2, and C3, where it absorbs diffuse sky background light, and finally strikes the photosensitive surface of the four-quadrant photodetector in the four-quadrant detector module 7. The photosensitive surface is divided into four quadrants, and each quadrant generates a photocurrent when illuminated. An algorithm controls the turntable's rotation based on the feedback response values ​​from the four quadrants, achieving precise sun tracking.

[0035] The four-quadrant photoelectric detector tracking principle is as follows:

[0036] The main current of the photocurrent output of each quadrant of the four-quadrant photodetector depends on two factors, namely the incident energy E and the area of ​​the light spot irradiated on the quadrant. If the light spot energy distribution is uniform and the energy is determined, the signal size of the photocurrent output by the four-quadrant photodetector depends only on the size of the light spot area on it. Figure 2 As shown, the spot position is solved using the following formula:

[0037]

[0038]

[0039] Among them, σ x and σ y Indicates the error signal of the spot position extracted on the X-axis and Y-axis, I a , I b , I c , I d Represents the output photocurrent in the four quadrants ABCD, E a 、E b 、E c 、E d Respectively represent the energy of the photocurrent received by each of the four quadrants, S a 、S b 、S c 、S d Indicates the spot area in the four quadrants.

[0040] According to the geometric relationship, it can be concluded that S a 、S b 、S c 、S d Relative to the relationship between the spot radius r, the spot center offset x0, y0, the above formula can be combined to obtain the error signal σx and σ y The relationship between the spot radius r and the spot center offset x0 and y0 is:

[0041]

[0042]

[0043] Can be launched:

[0044]

[0045]

[0046] Among them, I a , I b , I c , I d The values ​​represent the output photocurrents of the four quadrants A, B, C, and D on the four-quadrant photodetector, respectively. After passing through the acquisition circuit, UI conversion circuit, and filter amplification circuit, the values ​​returned to the computer represent the channel response values ​​for the four quadrants. The algorithm simulates the center position of the light spot at point G with coordinates (x0, y0). When point G is at (0, 0), the error signals on the X and Y axes are zero, indicating that the photocurrent response values ​​for the four quadrants are identical and the solar sensor is aligned with the sun.

[0047] Considering that the size of the four-quadrant photoelectric detector is 7.8 mm, according to the instruction manual of the four-quadrant photoelectric detector, the recommended spot size is between 1 and 7.8 mm.

[0048] In order to control the amount of solar radiation received by the four-quadrant photodetector, the aperture size of the light entrance circular aperture of the pre-aperture cylinder 6 needs to be designed. The present invention proposes an aperture design principle based on controlling the amount of energy received by the detector. The principle of the aperture design principle is as follows:

[0049]

[0050]

[0051] Among them, E T is the total solar irradiance per unit area received by the four-quadrant photoelectric detector within the (λ1, λ2) spectrum range, η λ is the response efficiency of the detector to the spectral radiation in the (λ1,λ2) spectral range, E λ is the solar irradiance in each spectral band within the (λ1,λ2) spectral range. I is the photocurrent value of the detector, φ is the solar radiation flux received by the photosensitive surface of the detector, A is the area of ​​the light entrance aperture, and R is the diameter of the light entrance aperture.

[0052] This design principle improves the detector's signal-to-noise ratio and achieves excellent response by controlling the photocurrent of the four-quadrant photodetector to approximately 50% of the detector's maximum response current. Calculated using the above formula, the input aperture diameter for achieving 50% of the maximum response current, based on the solar spectral irradiance curve at the Dunhuang summer solstice, should be 3.9 mm. Therefore, the pre-aperture tube 6 of the present invention preferably has an input aperture of 4 mm. It should be understood that the 4 mm value is merely a preference; the input aperture can be selected within 20 to 80% of the maximum response current.

[0053] Once the entrance aperture of the pre-aperture tube 6 is determined, its length can be determined by determining its field of view. In this invention, a preferred field of view is 10°, and the distance from the entrance aperture of the pre-aperture tube 6 to the photosensitive surface of the four-quadrant photodetector is 48 mm. The length of the pre-aperture tube 6 is preferably 65 mm, and the sensor base 8 is preferably 30 mm long, resulting in an overall structural length of 90 mm, with a maximum diameter of 36 mm.

[0054] like Figure 1 As shown in the figure, the clear apertures of the three levels of stray light diaphragm tubes (A1, B2, and C3) are primarily related to the field of view of the sun sensor. The size of the clear aperture is primarily determined by the line connecting the edge of the light entrance aperture and the edge of the detector's photosensitive surface. A clear aperture slightly larger than this line blocks most of the sky's stray light and improves the signal-to-noise ratio.

[0055] The axis of the coarse aiming circular hole on the pre-aperture cylinder 6 coincides with the axis of the coarse aiming target 5. When sunlight passes through the coarse aiming circular hole and the light spot falls on the center of the coarse aiming target 5, the coarse aiming alignment process is completed. The aperture of the coarse aiming circular hole ranges from 0.5 mm to 2 mm, preferably 1 mm in the present invention. The coarse aiming target 5 is preferably made of circular white polytetrafluoroethylene with the center position and a crosshair engraved on the white polytetrafluoroethylene. It should be understood that the coarse aiming target 5 can be made of other reflective or light-absorbing materials and can also have other shapes.

[0056] Ideally, when the sun sensor is aligned with the sun, the center of the light spot should coincide with the center of the four-quadrant photodetector's photosensor surface. Only when the two coincide is the light spot evenly distributed across the four quadrants of the detector's photosensor surface, and the photocurrent generated by each quadrant is identical. In reality, there will inevitably be a certain degree of offset between the two, preventing perfect overlap. This phenomenon can cause the light spot to be off-center on the four-quadrant photodetector's photosensor surface when the sun sensor is aligned perpendicularly to the sun, resulting in different response values ​​for the four channels and a certain degree of alignment error.

[0057] The present invention proposes a method based on mechanical assembly and instrument adjustment to ensure that the offset between the center of the light spot and the center of the photosensitive surface of the four-quadrant photodetector is within 0.01mm, and the angle error of the sun sensor aligned with the sun is controlled within 0.012°. Figure 3 As shown, the white circle is the circular circuit board in the four-quadrant photodetector module, the middle shaded part is the effective photosensitive surface of the four-quadrant detection photodetector, the middle white cross part is the dead zone of the photosensitive surface of the four-quadrant photodetector, and the outer circle is the cross-sectional plane of the cylindrical surface of the assembly surface of the sensor base.

[0058] Mechanical assembly: The pre-aperture cylinder 6 and the sensor base 8 are fitted together through a cylindrical mating surface clearance of less than 0.01mm, with the axis deviation between the two within 0.05mm. During machining, the coaxiality and cylindricity of the cylindrical mating surface must be strictly controlled to achieve the above-mentioned fitting accuracy.

[0059] Instrument installation and adjustment: Figure 3 As shown, place the sensor base 8 on the three-dimensional platform. Start tightening the screws of the four-quadrant photodetector module 7 until the spring washer begins to bear force. By adjusting the focusing microscope to focus on the cross-sectional plane of the cylindrical assembly surface, find the left and right vertical tangent coordinates S of the cylindrical assembly surface. L and S R , then find the horizontal tangent coordinate T H and T R The center of rotation O' of the cylindrical mating surface is Next, adjust the focusing microscope to align the photosensitive surface of the four-quadrant photodetector. Move the 3D platform to the coordinates of the rotation center O', so that the crosshairs of the focusing microscope align with O'. By tapping with an observation tool and manually fine-tuning, move the dead zone center O until it coincides with O'. Because the dead zone width is only 0.018mm, manual centering is accurate within 0.005mm. After adjusting the position, tighten the screws and observe whether the O coordinate changes. If so, repeat the above steps until there is no change. This completes the instrument adjustment process.

[0060] Before use, a four-quadrant photodetector requires calibration. The goal of this calibration is to ensure that the four channels in each quadrant produce the same digital signal for the same irradiance. It's important to understand that a channel refers to the photodiode in each quadrant and its corresponding data acquisition, amplification, current-to-voltage conversion, and filtering circuits.

[0061] Therefore, this paper proposes a calibration method for a four-quadrant photodetector for uniform light detection. This method uses solar radiation to calibrate the consistency of the response of the solar sensor to light sources of the same irradiance across four channels. This method can reduce the inconsistency from 1-2% to within 0.2%, significantly improving the accuracy of the four-quadrant light spot positioning.

[0062] like Figure 4 As shown, based on the outdoor sun tracking process, the calibration method of the ground high-precision four-quadrant sun sensor of the present invention includes the following steps:

[0063] The first step is to conduct a calibration experiment in sunny weather with few clouds. This way, the solar radiation is strong and there is less diffuse light in the sky, which is conducive to the response of the detector.

[0064] The second step is to fix the sensor base 8 to the dual-axis automatic turntable through the through-hole reserved in the base. Make sure that the sensor base 8 is placed horizontally on the plane of the dual-axis automatic turntable. Then fix the front aperture tube 6 to the sensor base 8 through threads. Finally, by adjusting the elevation angle and azimuth angle of the dual-axis automatic turntable, align the solar spot falling through the coarse aiming circular hole in the front aperture tube 6 with the coarse aiming target 5 made of white polytetrafluoroethylene to complete the coarse alignment of the solar sensor with the sun. At this time, the azimuth and elevation angles of the dual-axis automatic turntable can be set as the starting tracking angle. According to the real-time solar trajectory calculated in the astronomical calendar, set the computer program to start automatic tracking. At this time, the real-time tracking error is within ±2°.

[0065] Step 3: Figure 5 As shown, the pre-aperture tube 6 is removed and replaced with a stray light suppression tube 9 with an incident aperture larger than the detector's photosensitive surface area. This is then screwed onto the sensor base 8. The stray light suppression tube 9 of the present invention preferably has an incident aperture of 14 mm, larger than the 7.8 mm of the selected detector. This ensures that incoming sunlight completely covers the detector's photosensitive surface but does not strike the inner wall of the pre-aperture tube 6 and cause reflections. The second step, coarse aiming, ensures that the sun's incidence is approximately perpendicular to the detector's photosensitive surface during calibration. Because the four-quadrant photodetectors of the four-quadrant detector module 7 are protected by a metal encapsulation, the inner wall is not blackened and has a high reflectivity. Maintaining approximately perpendicular incidence ensures that sunlight does not strike the inner wall of the encapsulation. According to the laws of optical reflection, if sunlight strikes the inner wall of the encapsulation, the response values ​​of the four quadrants of the detector's photosensitive surface will be inconsistent, increasing the error in the calibration experiment.

[0066] Step 4: During the cloud-free period between 10:00 and 14:00, collect the response values ​​of the four channels of the four-quadrant photoelectric detector. Each acquisition time should be less than 1 second, and multiple data sets should be collected. The number of acquisition sets should preferably be less than 100. The acquisition time points should be as evenly spaced as possible, and the acquisition time should be symmetrical. Do not collect multiple sets in a single time period.

[0067] Step 5: After collecting all the data, average the channel values ​​for each group to obtain the response value for each channel. Subtract the ambient light noise for each channel. Use the response value of the first channel as the denominator and the values ​​of the remaining three channels as the numerator to obtain the deviation coefficient for each channel. This yields the deviation coefficients for each channel under different light intensities, and the weighted average is taken to obtain the compensation coefficient for each channel.

[0068] Step 6: Add compensation coefficients to the computer program. This compensation coefficient ensures that the four channels of the four-quadrant photodetector respond identically to the same irradiance light source, completing the calibration process for the consistency of the response of each channel of the solar sensor to uniform light.

[0069] The embodiments described above are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A calibration method for a ground-based high-precision four-quadrant sun sensor, characterized in that: The ground-based high-precision four-quadrant solar sensor comprises a stray light diaphragm tube A, a stray light diaphragm tube B, a stray light diaphragm tube C, a clamping washer, a coarse aiming target, a front diaphragm tube, a four-quadrant photoelectric detector module and a sensor base; the main structure of the ground-based high-precision four-quadrant solar sensor comprises a front diaphragm tube and a sensor base below it, the two are connected by threaded matching, and are fixed by the assembly surface under the thread; the first step of the sensor base is a thread, and the second step is an assembly surface, and the assembly surface adopts a clearance fit; the stray light diaphragm tube A, the stray light diaphragm tube B, and the stray light diaphragm tube C inside the front diaphragm tube are fixed by tightening upwards through the inner wall thread of the clamping washer; the coarse aiming target is connected to the screw hole of the front diaphragm tube by thread; the sensor base has a through hole and is connected to the solar observation instrument by screws; the axis of the coarse aiming circular hole on the front diaphragm tube coincides with the axis of the coarse aiming target; The calibration method comprises the following steps: The first step is to select a weather with few clouds and good sunshine to conduct the calibration experiment; The second step is to fix the sensor base to the dual-axis automatic turntable through the reserved through hole; by adjusting the elevation angle and azimuth angle of the dual-axis automatic turntable, align the sun spot falling through the coarse aiming circular hole in the front aperture tube with the center of the coarse aiming target of white polytetrafluoroethylene, and complete the coarse aiming of the solar sensor to the sun; at this time, the azimuth angle and elevation angle of the dual-axis automatic turntable are set as the starting tracking angle, and according to the real-time solar trajectory calculated in the astronomical calendar, the program in the computer is set to start automatic tracking; Step 3: Remove the front aperture tube and replace it with stray light elimination aperture tube A, stray light elimination aperture tube B, and stray light elimination aperture tube C, whose incident aperture is larger than the diameter of the photosensitive surface of the four-quadrant photoelectric detector module, and fix them on the sensor base through threads; Step 4: In the cloud-free period, collect the response values ​​of the four channels of the four-quadrant photoelectric detector; each collection time is within 0.1s, and multiple groups of data are collected; the collection time points are equidistant, and the collection time periods are symmetrical; Step 5. After all data are collected, the channel values ​​of each group are averaged to obtain the response value of each channel; the ambient light background noise of each channel is deducted, and the response value of the first channel is used as the denominator, and the values ​​of the other three channels are used as the numerator to obtain the deviation coefficient of each channel, thereby obtaining the deviation coefficient of each channel under different light intensities, and taking the weighted average to obtain the compensation coefficient of each channel; Step 6: Input the compensation coefficient into the computer program. The addition of the compensation coefficient makes the four channels of the solar sensor produce the same response to the light source of the same irradiance, thus completing the calibration process of the consistency of the response of each channel of the solar sensor to uniform light.

2. The calibration method according to claim 1, characterized in that: The incident aperture of the front aperture is designed according to the control of the detector receiving energy; the radiation flux of the incident light is controlled according to the maximum response current of the detector, and the incident aperture size is inferred based on the size of the radiation flux of the incident light, the solar spectrum irradiance curve at the summer solstice, and the detector's spectral response efficiency curve.

3. The calibration method according to claim 1, characterized in that: The field of view of the sun sensor is selected to be in the range of about 15°, and the overall length range is 40-100mm; the front aperture tube is composed of stray light elimination aperture tube A, stray light elimination aperture tube B, and stray light elimination aperture tube C to absorb the diffuse background light from the sky.

4. The calibration method according to claim 1, characterized in that: The front aperture tube and the sensor base are matched through the clearance of the cylindrical assembly surface to complete the centering assembly; using a focus-adjustable microscope and a three-dimensional mobile platform, the deviation between the center of the four-quadrant photosensitive surface and the center of the matching surface is adjusted to within 0.005mm, so that the offset of the center position of the light spot and the center position of the photosensitive surface of the four-quadrant photoelectric detector of the four-quadrant photoelectric detector module is within 0.01mm, that is, the angle error of the solar sensor aligned with the sun is controlled within 0.012°.

5. The calibration method according to claim 1, characterized in that: The diameter of the coarse aiming circular hole is 0.5 mm to 2 mm, and the coarse aiming target is white polytetrafluoroethylene, on which the center position and a cross positioning mark are engraved.

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