Laboratory low-temperature radiometric calibration device and calibration method suitable for spaceflight optical remote sensing camera

Abstract

The invention belongs to the technical field of spacecraft environment simulation, aims to solve the problems that in existing optical remote sensing camera ground laboratory radiometric calibration, the temperature calibration range is not matched with the actual on-orbit demand, and the calibration environment control precision is insufficient, and provides a laboratory low-temperature radiometric calibration device and calibration method suitable for a spaceflight optical remote sensing camera. The device comprises a structure system, a maintenance system and a temperature and humidity control system, wherein the structure system is of a cubic frame type and provides an anti-deformation stable carrying foundation; the maintenance system is responsible for shading, stray light prevention, heat preservation and protection and comprises a face wall plate and a glass window, and the face wall plate is arranged corresponding to the side face of the frame and extends forwards to cover a light outlet of the integrating sphere to achieve shading; the glass window is liftable multi-layer toughened glass and is arranged on the side surface of the frame corresponding to the integrating sphere, and the size is slightly larger than the aperture of the integrating sphere. The temperature and humidity control system realizes 10-15 + / -0.2 DEG C low-temperature precise closed-loop control and automatic humidity regulation and control. The system is suitable for optical remote sensing camera calibration.

Description

Technical Field

[0001] This invention belongs to the field of spacecraft environment simulation technology, specifically relating to a device and method for simulating on-orbit cryogenic radiation calibration of a space optical remote sensing camera laboratory. Background Technology

[0002] Since radiometric calibration experiments require long-term imaging of a stable light source over a wide temperature range, these experiments cannot be conducted while the satellite is in orbit. Therefore, radiometric calibration in ground laboratories has become an indispensable and important testing step in the research and development and production of optical remote sensing cameras. Its calibration accuracy directly affects the processing effect and application value of subsequent on-orbit image data.

[0003] Currently, existing ground-based laboratory radiometric calibration techniques are all conducted under ambient temperature conditions, with the standard laboratory environment temperature set at 20°C, and the detector temperatures for the collected data all above 20°C. However, during satellite operation in orbit, the initial operating temperature of optical remote sensing camera detectors is generally designed to be 15°C. This results in a temperature deviation of more than 5°C between the ground-based laboratory calibration environment and the actual operating environment of the satellite in orbit. Furthermore, considering the non-linear temperature shift characteristics of detectors such as CCDs, this situation leads to poor correction results when using laboratory calibration coefficients to correct image data acquired after orbit insertion, making it impossible to realistically simulate the actual in-orbit temperature of the optical remote sensing camera. Therefore, the limitations of the existing technologies mentioned above have led to a series of problems: First, since the laboratory radiometric calibration temperature range is above 20℃, which does not match the 15℃ temperature distribution range in orbit, the extrapolation of model coefficients has a significant impact on the results, making them unusable in orbit and requiring radiometric calibration tests covering the in-orbit temperature range; Second, after radiometric correction of in-orbit images using existing laboratory calibration coefficients, residual color differences often remain, requiring additional post-processing, which not only increases data processing costs but also affects the image visualization effect; Third, existing calibration technologies cannot achieve precise control over the payload test environment, making them susceptible to environmental interference during the calibration process, resulting in large calibration errors and difficulty in guaranteeing calibration quality, thus prolonging the satellite's in-orbit calibration time; In addition, existing technologies are difficult to adapt to the calibration requirements in mass production of cameras, limiting their application in large-scale production scenarios.

[0004] In summary, existing ground-based radiometric calibration technologies for optical remote sensing cameras suffer from problems such as mismatch between the temperature calibration range and actual on-orbit requirements, and insufficient precision in calibration environment control. These issues result in poor calibration data accuracy, unsatisfactory on-orbit correction effects, low calibration efficiency, and limited adaptability, failing to meet the demands of high-precision R&D and mass production of optical remote sensing cameras. Therefore, developing a radiometric calibration technology and device that can cover the on-orbit temperature range and achieve precise environmental control has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a low-temperature radiometric calibration device suitable for optical remote sensing cameras. This device is placed in front of the light outlet of an integrating sphere, and the camera under test is placed inside the device. Through temperature and humidity control, the device can simulate the on-orbit state of the calibration test temperature, improving the accuracy of laboratory calibration. It also improves the quality of laboratory radiometric calibration and shortens the on-orbit calibration time through precise control of the load test environment. Furthermore, it reduces calibration errors caused by environmental factors, obtaining more accurate calibration data. Simultaneously, it solves the problem of stray light interference from multiple radiometric calibration experimental devices in the laboratory, preventing parallel testing. This invention is suitable for both single-camera R&D and mass production of cameras. It has advantages such as simple structure, short development cycle, and low manufacturing cost.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a laboratory low-temperature radiation calibration device suitable for aerospace optical remote sensing cameras. The calibration device is located in front of the light outlet of an integrating sphere and includes a structural system, a maintenance system, and a temperature and humidity control system. The structural system is a cubic frame structure, used to provide a stable mounting base that resists deformation; The maintenance system is used to achieve functions such as shading and preventing stray light, heat preservation and safety protection, including wall panels and glass windows; The wall panel is provided on the side of the cube frame and extends forward to form a light-shielding structure, covering the light outlet of the integrating sphere, so that the light shielding extends to the plane of the light outlet of the integrating sphere. The glass window is a liftable multi-layer tempered glass structure, set on the side of the cubic frame corresponding to the integrating sphere, and its size is slightly larger than the diameter of the integrating sphere. The temperature and humidity control system is used to achieve precise closed-loop control at low temperatures of 10~15±0.2℃ and automatic humidity regulation.

[0007] Furthermore, the aforementioned wall panels are made of black cleanroom color steel rock wool sandwich panels to reduce heat loss and isolate stray light interference, thus ensuring calibration accuracy.

[0008] Furthermore, the aforementioned maintenance system also includes a cleanroom door, which is designed to open outwards and is made of the same material as the wall panel. This door works together to achieve internal and external insulation and light isolation, thereby enhancing maintenance convenience and protection.

[0009] Furthermore, the aforementioned glass window is equipped with an automated lifting assembly to achieve controllable opening and closing, including a glass that can slide up and down, an electric glass lift, a window counterweight, and a sliding guide rail. The glass is embedded in the sliding guide rail and is connected to the electric glass lift and the window counterweight, respectively, and can achieve uniform lifting and partial / complete opening and closing through remote control.

[0010] Furthermore, the aforementioned temperature and humidity control system includes a refrigeration unit, an air conditioner, and an electric heater; The condenser end of the refrigeration unit is connected to process cooling water, which provides a cold source to the calibration device through refrigeration pipes; The air conditioner is used to deliver cold air to the calibration device under the action of a cold source, and to adjust the temperature by adjusting the flow rate of the refrigerant water in the air conditioner. At the same time, the air conditioner is connected to a condensate pipe, through which the condensate water is discharged into a drain bucket. The electric heater is installed inside the air supply duct of the air conditioner and is used to finely adjust the supply air temperature.

[0011] Furthermore, the aforementioned temperature and humidity control system also includes a supply and return air system and a dehumidifier; The dehumidifier is used to dehumidify the low-temperature radiation calibration device; The supply and return air system is used to achieve airflow circulation.

[0012] Furthermore, the aforementioned dehumidifier turns on when the humidity is above 65% and turns off when it is below 50%.

[0013] Furthermore, the low-temperature closed-loop control logic of the above-mentioned temperature and humidity control system is as follows: the temperature sensor in the device collects temperature data in real time, and dynamically adjusts the heating power of the electric heater and the cooling power of the refrigeration unit through the algorithm. When the temperature is lower than the target range of 10~15℃, the electric heater is started to heat up and finely adjust the temperature; when the temperature is higher than the target range, the cold source supply is increased to cool down, so as to ensure that the outlet water temperature of the refrigeration unit is stable within ±0.2℃, and achieve precise and controllable low temperature.

[0014] Furthermore, the heating power of the electric heater and the cooling power of the refrigeration unit are dynamically adjusted through a fuzzy PID algorithm. The algorithm establishes a fuzzy rule base for temperature deviation and deviation change rate, and self-tunes the PID parameters to suppress thermal inertia overshoot. When the temperature is below the target range of 10~15℃, the electric heater is started to raise the temperature for fine adjustment; when the temperature is above the target range, the cold source supply is increased to lower the temperature, ensuring that the outlet water temperature of the refrigeration unit is stable within ±0.2℃, thus achieving precise and controllable low temperature.

[0015] Secondly, the present invention also provides a calibration method based on a low-temperature radiation calibration device, the method comprising the following steps: A stable cubic frame is built by the structural system and an integrating sphere is installed. The light-shielding structure is formed by the maintenance system wall panels to cover the light outlet of the integrating sphere, and the purification door and glass window are closed to achieve full-enclosed light-shielding and heat preservation. The temperature and humidity control system is activated, and a fuzzy PID algorithm is used for closed-loop temperature control. Data is collected through temperature sensors, and temperature deviation and rate of change are calculated. The PID parameters are self-tuned to adjust the power of the electric heater and the chiller, so that the outlet water temperature of the chiller is stabilized within ±0.2℃. The dehumidifier controls humidity according to the threshold of 65% on and 50% off, and works with the supply and return air system to achieve uniform temperature and humidity distribution. After the temperature and humidity stabilize, the opening range of the glass is adjusted remotely through the automatic lifting component of the glass window to align the light output port of the integrating sphere with the equipment to be calibrated, and the integrating sphere is started to carry out calibration.

[0016] The beneficial effects of this invention are as follows: This invention develops a low-temperature radiometric calibration device suitable for optical remote sensing cameras. It can simulate the on-orbit state of calibration test temperature, improve the accuracy of laboratory calibration, improve the quality of laboratory radiometric calibration and shorten the on-orbit calibration time through precise control of the load test environment, and reduce calibration errors caused by environmental factors, so as to obtain more accurate calibration data. It is suitable for both the research and development of single cameras and the mass production of cameras.

[0017] Furthermore, this invention can simulate the low-temperature environment of a satellite in orbit, enabling low-temperature calibration tests and improving the accuracy of laboratory calibration. Furthermore, this invention achieves precise control of the load test environment through a temperature and humidity control system, thereby improving the quality of laboratory radiation calibration and shortening the on-orbit calibration time. Furthermore, this invention solves the problem of stray light interference in parallel calibration of multiple devices, thereby improving calibration efficiency. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is an axonometric view of the structural frame of the low-temperature radiation calibration device described in this invention; Figure 2 This is a plan view of the low-temperature radiation calibration device described in this invention; Figure 3 This is a schematic diagram of the installation of the cleanroom window described in this invention; Figure 4 This is a schematic diagram of the temperature and humidity control system of the low-temperature radiation calibration device described in this invention; Figure 5 The refrigeration unit control panel described in this invention; Figure 6 This is the control panel of the dehumidifier described in this invention.

[0020] Among them, 101-square steel beam, 102-angle iron bracing, 103-square steel column, 104-steel column corner, 201-cleanroom door, 202-wall panel, 203-glass window, 204-light-blocking extension, 301-glass, 302-electric glass lift, 303-window counterweight, 304-sliding guide rail, 401-refrigeration unit, 402-air conditioner, 403-electric heater, 404-supply and return air system, 405-dehumidifier, 406-refrigeration pipe, 407-condensate pipe, 408-drainage tank, 409-air supply duct. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

[0022] Example 1, Combination Figures 1 to 6 This embodiment describes a low-temperature radiometric calibration device suitable for optical remote sensing cameras. The device is placed in front of the light outlet of an integrating sphere, and the camera under test is placed inside. Through temperature and humidity control, the device can simulate the on-orbit temperature for calibration tests, improving laboratory calibration accuracy. It also improves the quality of laboratory radiometric calibration and shortens on-orbit calibration time through precise control of the load test environment. Furthermore, it reduces calibration errors caused by environmental factors, obtaining more accurate calibration data. Simultaneously, it solves the problem of stray light interference from multiple radiometric calibration experimental devices in the laboratory, preventing parallel testing. This device is suitable for both single-camera R&D and mass production of cameras.

[0023] The proposed low-temperature radiometric calibration device for optical remote sensing cameras includes: a structural system, a maintenance system, and a temperature and humidity control system; The structural system is a cubic frame structure, used to provide a stable mounting base that resists deformation; The maintenance system is used to achieve functions such as shading and preventing stray light, heat preservation and safety protection, including a wall panel 202 and a glass window 203; The wall panel 202 is provided on the side of the cube frame and extends forward to form a light-shielding structure, and covers the light outlet of the integrating sphere, so that the light-shielding extends to the plane of the light outlet of the integrating sphere. The glass window 203 is a liftable multi-layer tempered glass structure, which is set on the side of the cubic frame corresponding to the integrating sphere, and its size is slightly larger than the diameter of the integrating sphere. The temperature and humidity control system is used to achieve precise closed-loop control at low temperatures of 10~15±0.2℃ and automatic humidity regulation.

[0024] Furthermore, the above system is more specifically defined as follows: The structural system is as follows Figure 1 As shown, the overall structure is a cubic frame made of galvanized square steel beams. The top is composed of four square steel beams 101, and the sides are composed of four square steel columns 103. The bottom of each steel column is fixed to the ground by steel column corners 104. Angle iron bracing 102 is set between the steel beams and between the steel beams and the steel columns, which makes the overall frame solid and stable, the system frame is not easy to deform, and the installation is simple and easy to transport.

[0025] The maintenance system is as follows Figure 2 As shown, it includes a wall panel 202, a cleanroom door 201, and a glass window 203. The wall panel 202 consists of four sides of a cubic frame structure, and it wraps around the light outlet of the integrating sphere, extending the shading extension 204 to the plane of the integrating sphere's light outlet, thus ensuring effective shading. In practical applications, the wall panel 202 uses black cleanroom color-coated steel rock wool sandwich panels. This product features low light absorption, purification, and low heat conduction, preventing heat loss and effectively controlling temperature, while ensuring calibration accuracy is not affected by stray light. The cleanroom door 201 is an outward-opening type, also made of black cleanroom color-coated steel rock wool sandwich panels, effectively controlling temperature and ensuring calibration accuracy is not affected by stray light. The glass window 203 is custom-made with three layers of tempered glass, slightly larger than the diameter of the integrating sphere. Due to the large temperature difference between the indoor temperature and the integrating sphere's heating temperature, it reduces heat conduction efficiency, achieving better insulation. Meanwhile, as... Figure 3 As shown, the glass window 203 is equipped with a sliding glass 301, an electric glass lift 302, a window counterweight 303, and a sliding rail 304 for automated lifting control. The glass 301 is embedded in the sliding rail 304 and connected to the electric lift 302 and the window counterweight 303. It can be remotely controlled to rise at a constant speed under the combined action of the electric lift 302 and the window counterweight 303 until it is partially or fully opened; it can also be remotely controlled to descend at a constant speed until it is partially or fully closed. The window counterweight 303 mainly serves to counteract the weight of the glass 301 during its descent, preventing the glass 301 from suddenly falling due to motor damage and causing a safety accident.

[0026] The temperature and humidity control system includes a temperature control system with a control accuracy of 10~15±0.2℃. It employs a water-cooled chiller unit for cooling and a ducted fan for air supply. Electrical heating is used at the terminal for fine-tuning the temperature. Due to the low supply air temperature, antifreeze is added to the system to prevent the evaporator of the chiller from freezing and cracking. The water-cooled chiller unit is placed indoors, using process cooling water to remove the heat load, thus avoiding noise and indoor heat dissipation. The system also includes a humidity control system. By adding a dehumidifier, it ensures that the humidity meets the requirements of each test when the temperature reaches the set values. The dehumidifier can be programmed to turn on when the humidity exceeds a certain value and turn off when it drops to a certain value.

[0027] The temperature and humidity control system, such as Figure 4 As shown, the system includes a chiller 401, an air conditioner 402, an electric heater 403, a supply and return air system 404, and a dehumidifier 405. The chiller 401 primarily provides a cold source for the low-temperature radiation calibration device. The chiller 401 and its refrigeration pipes 406 are filled with ethylene glycol antifreeze to ensure that the equipment and pipes do not freeze at low temperatures. The condenser end of the chiller 401 is connected to process cooling water for cooling. The air conditioner 402 supplies cold air to the low-temperature radiation calibration device and adjusts the temperature by regulating the refrigerant flow rate of the air conditioner. Simultaneously, the air conditioner is connected to a condensate drain pipe 407, through which condensate is drained into a drain tank 408. The electric heater 403 is installed inside the air supply duct 409 of the air conditioner to fine-tune the supply air temperature. The supply and return air system 404 is a galvanized ductwork covered with B1-grade pixel insulation material.

[0028] Since the temperature calibration range for laboratory radiation calibration is above 20°C, which does not match the 15°C temperature distribution range of satellites in orbit, the low-temperature radiation calibration device proposed in this invention has a temperature control accuracy of 10~15±0.2°C. This can simulate low-temperature environments that cannot be achieved in laboratory radiation calibration. Its working principle is as follows: chilled water from the chiller 401 is continuously supplied to the low-temperature radiation calibration device via the air conditioner 402. Temperature sensors inside the device collect the temperature in real time. Through algorithms, the power of the pipe heaters and chiller unit is adjusted to ensure the chiller outlet water temperature remains stable within ±0.2°C. When the temperature is lower than the target temperature, the electric heater 403 finely adjusts the temperature to raise it. When the temperature is higher than the target temperature, the chiller 401 and air conditioner 402 provide cooling, achieving automated and stable temperature control. The dehumidifier 405 dehumidifies the low-temperature radiation calibration device, turning on when the humidity is above 65% and turning off when it is below 50%. The air supply and return system 404 is connected to the low-temperature radiation calibration device, wherein the air supply pipe is connected to the air supply duct 409 of the air conditioner for temperature treatment, and the return air pipe is connected to the wall panel 202 of the low-temperature radiation calibration device.

[0029] Furthermore, in practical applications, the heating power of the electric heater and the cooling power of the refrigeration unit can be dynamically adjusted through a fuzzy PID algorithm. The algorithm establishes a fuzzy rule base for temperature deviation and deviation change rate, and self-defines PID parameters to suppress thermal inertia overshoot. When the temperature is below the target range of 10~15℃, the electric heater is activated for temperature rise and fine adjustment; when the temperature is above the target range, the cold source supply is increased to cool down, ensuring that the outlet water temperature of the refrigeration unit is stable within ±0.2℃, achieving precise and controllable low temperature.

[0030] The fuzzy PID algorithm mainly includes three core modules: fuzzification processing, fuzzy rule base, and defuzzification processing. These modules work together to achieve self-tuning of control parameters, as detailed below: Fuzziness processing module: Selects the deviation between the actual temperature and the target temperature within a preset range of 10~15℃ in the calibration device. e Deviation change rate ec As a fuzzy input quantity. First, set... e The value range is [-2℃, +2℃], corresponding to a temperature deviation of ±2℃, covering the disturbance range of the precise temperature control zone. ec The value range is [-0.5℃ / s, +0.5℃ / s], set based on the thermal inertia characteristics of the temperature control system; subsequently, continuous... e and ec Discretize the input quantities into fuzzy sets such as {negative large, negative medium, negative small, zero, positive small, positive medium, positive large}, and map the input quantities to fuzzy variables through triangular membership functions, providing a basis for subsequent reasoning; Fuzzy rule base module: Based on the temperature control characteristics of the calibration device, multiple sets of fuzzy control rules are constructed. The core logic is "based on deviation..." e and rate of change of deviation ec Fuzzy combination, dynamically adjust the proportional coefficient of the PID controller Kp Integral coefficient Ki Differential coefficients Kd This ensures the adaptability of control under different operating conditions. For example, when the temperature deviation... e The actual temperature of "Zhengda" was much higher than the target value, and the deviation rate was significantly higher. ec When the temperature is still rising rapidly, the output rule is "increase". Kp , reduce Ki Increase Kd This achieves rapid cooling and suppresses overshoot; when temperature deviation... e The actual temperature is slightly higher than the target value, and the deviation rate is "positive small". ec When the temperature approaches zero and stabilizes, the output rule is to "decrease". Kp Increase Ki , reduce Kd "To avoid excessive cooling and ensure steady-state accuracy; when temperature deviation..." eFor "negative small", the actual temperature is slightly lower than the target value, and the deviation change rate is... ec When the temperature decreases slowly ("negative small"), the output rule is "moderate". Kp Moderate Ki Moderate Kd The rule base contains 49 core rules and 7 sub-rules, with the temperature increased slightly by an electric heater to compensate for heat loss. e 7 groups of fuzzy variables ec Fuzzy variables cover all possible temperature control conditions; Refurbishment module: Uses the centroid method to refine the fuzzy inference results. Kp , Ki , Kd The fuzzy value is converted into a continuous, precise value. Simultaneously, considering the hardware response characteristics of the temperature control system, such as the cooling capacity adjustment delay of the refrigeration unit and the power adjustment step size of the electric heater, the precise value is subjected to amplitude limiting. Kp , Ki , Kd The appropriate value range is determined to avoid exceeding the hardware adjustment capability. Finally, the tuned PID parameters are input into the controller to drive the electric heater and refrigerator to perform corresponding actions.

[0031] Furthermore, the collaborative control process between the fuzzy PID algorithm and the calibration device hardware is as follows: Temperature acquisition: Temperature sensors installed inside the calibration device collect internal temperature data in real time and transmit the data to the controller every 0.1 seconds. The controller calculates the deviation between the actual temperature and the target temperature. e and the rate of change of deviation ec ; Parameter tuning: Fuzzy PID algorithm for e and ec Fuzzification is performed, and fuzzy rule base inference is called to obtain a result suitable for the current working conditions. Kp , Ki , Kd Parameters, and complete the sharpening and limiting processing; Control execution: Based on the tuned PID parameters, the controller outputs control signals: If the temperature is 10~15℃ higher than the target range, the cooling power of the chiller is increased and the refrigerant water flow is adjusted. At the same time, the air supply efficiency of the air conditioner is adjusted according to the deviation to quickly cool down; If the temperature is lower than the target range, the electric heater is started and the heating power is precisely adjusted through the PID algorithm to slightly increase the temperature to compensate for heat loss. Feedback closed loop: The temperature sensor continuously collects the temperature data after regulation, repeats the above steps, and dynamically updates the PID parameters to ensure that the chiller outlet water temperature is stable within ±0.2℃, thus achieving precise closed-loop control at low temperatures.

[0032] Therefore, it can be seen that the fuzzy PID algorithm used in this embodiment has the following significant technical advantages compared with traditional control algorithms in the temperature control scenario of calibration devices: Improved temperature control accuracy and stability: By dynamically and automatically setting PID parameters, the influence of thermal inertia of the integrating sphere and environmental disturbances is effectively suppressed, improving the temperature control accuracy from ±0.5℃ of the traditional algorithm to ±0.2℃, which fully meets the requirements of satellite on-orbit temperature simulation and ensures the accuracy of radiation calibration. Reduce overshoot and oscillation: The fuzzy rule base optimizes the control logic for different deviation scenarios, which can control the temperature overshoot to below 0.5%, avoid the performance of the integrating sphere being affected by drastic temperature fluctuations, and at the same time reduce the frequent start-stop of the refrigerator and electric heater, thus extending the service life of the equipment. Enhanced adaptability to operating conditions: The algorithm can adapt to dynamic operating conditions such as changes in the heating power of the integrating sphere and fluctuations in the temperature and humidity of the laboratory environment, without the need for manual intervention to adjust parameters. This solves the problem of decreased accuracy of traditional algorithms when the load changes suddenly, and improves the automation level and reliability of the device. Synergistic enhancement of system performance: It works in synergy with the low thermal conductivity wall panel and triple tempered glass window of the maintenance system. The algorithm's precise control, combined with the hardware insulation design, further reduces heat loss and energy consumption. At the same time, it avoids the coupling effect of stray light interference and temperature fluctuations, ensuring calibration quality in all aspects.

[0033] Furthermore, the temperature and humidity control system has an interface that allows for one-button start and stop of the system. Through parameter settings, the laboratory temperature can be set between 8 and 25°C, and the relative humidity between 30% and 70%RH. Operating data—the laboratory temperature and humidity—can be recorded and queried via data curves or real-time data. The system also includes an alarm feedback mechanism; malfunctions in key components such as the chiller 401, air conditioner 402, electric heater 403, and dehumidifier 405 will trigger an alarm via system software. The start and stop of the chiller 401 are remotely controlled by the control system, and the chiller control panel is shown below. Figure 5 As shown.

[0034] The operating procedure is as follows: To start the refrigeration unit: ① Click the "Pump" button, the indicator light will illuminate; ② Click the "Compressor" button, the indicator light will illuminate, and the start-up is complete.

[0035] To stop the refrigeration unit: ① Click the "Compressor" button; the indicator light will turn off after a delay. ② Click the "Pump" button; the indicator light will turn off completely, completing the shutdown process.

[0036] The dehumidifier 405 is remotely controlled by a control system. The control panel of the dehumidifier 405 is as follows: Figure 6 As shown, after completing the humidity setting, you can press the "Start" / "Stop" button to turn the dehumidifier 405 on / off with one click. The dehumidifier 405 can also be operated manually: Step 1: Press "Manual Operation" to switch the unit program to manual mode.

[0037] Step 2: Press the number key "1" to start the regeneration fan; Step 3: Press the number key "2" to start the rotary motor; Step 4: Press the number key "3" to start the dehumidifier; After manually performing the above steps, the unit will start operating.

[0038] The electric heater 403 uses both duct heating and pipe heating, each with two levels of protection. The duct heating mainly features no-airflow protection and overheat protection, while the pipe heating mainly features a water flow switch and overheat protection. If any of these protection measures trigger an alarm, the power supply will be automatically disconnected.

[0039] Example 2: This example provides a calibration method for the cryogenic radiometric calibration device for aerospace optical remote sensing cameras described in Example 1. The method includes the following steps: (1) Device setup and initialization: Construct a stable cubic frame through the structural system, install the integrating sphere in the frame, extend the wall panel of the maintenance system forward to form a light-shielding structure, cover the light-emitting port plane of the integrating sphere, close the outward-opening purification door, and adjust the glass window to the closed state to achieve full-closure light-shielding and heat preservation of the light-emitting port of the integrating sphere. (2) Precise temperature and humidity control: The temperature and humidity control system is started, and the fuzzy PID algorithm is used to control the calibration environment temperature in a closed loop. The temperature data inside the device is collected in real time by the temperature sensor. The deviation and deviation rate between the actual temperature and the target temperature of 10~15℃ are calculated. After fuzzification, fuzzy rule base reasoning and clearing processing, the PID parameters are dynamically self-tuned to adjust the heating power of the electric heater and the cooling power of the refrigeration unit so that the outlet water temperature of the refrigeration unit is stable within ±0.2℃. At the same time, the dehumidifier is turned on when the humidity is above 65% and turned off when it is below 50% to control the ambient humidity. The supply and return air system is used to achieve uniform temperature and humidity distribution. (3) Calibration preparation and execution: After the temperature and humidity inside the device stabilize to the preset range, the glass is driven to rise at a constant speed along the sliding guide rail by the automatic lifting component of the glass window. The opening range of the glass is adjusted according to the calibration requirements so that the light outlet of the integrating sphere is aligned with the equipment to be calibrated. (4) Calibration process control and completion: After the integrating sphere starts working, the fuzzy PID algorithm continuously and dynamically controls the temperature, and the maintenance system is kept in a state of light shielding and heat preservation to avoid stray light interference and temperature fluctuations; after calibration is completed, the glass window is closed by remote control, the integrating sphere and temperature and humidity control system are turned off, and after the temperature inside the device returns to the ambient temperature, the cleanroom door is opened to complete the subsequent cleaning.

[0040] In summary, the low-temperature radiation calibration device proposed in this invention can effectively simulate the low-temperature environment of satellites in orbit, realize low-temperature calibration experiments, improve the quality of laboratory radiation calibration, shorten the in-orbit calibration time, and also solve the problem of stray light interference in parallel calibration of multiple devices, thereby improving calibration efficiency.

[0041] The above description of the technical solution provided by the present invention through several specific embodiments is intended to highlight the advantages and benefits of the technical solution provided by the present invention. However, the above-described specific embodiments are not intended to limit the present invention. Any reasonable modifications and improvements to the present invention, reasonable combinations of implementation methods and equivalent substitutions based on the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A laboratory cryogenic radiation calibration device suitable for aerospace optical remote sensing cameras, wherein the calibration device is positioned in front of the light outlet of an integrating sphere, characterized in that, The calibration device includes a structural system, a maintenance system, and a temperature and humidity control system; The structural system is a cubic frame structure, used to provide a stable mounting base that resists deformation; The maintenance system is used to achieve functions such as shading and preventing stray light, heat preservation and safety protection, including a wall panel (202) and a glass window (203). The wall panel (202) is provided on the side of the cube frame and extends forward to form a light-shielding structure, and covers the light outlet of the integrating sphere, so that the light-shielding extends to the plane of the light outlet of the integrating sphere. The glass window (203) is a liftable multi-layer tempered glass structure, which is set on the side of the cubic frame corresponding to the integrating sphere, and its size is slightly larger than the diameter of the integrating sphere. The temperature and humidity control system is used to achieve precise closed-loop control at low temperatures of 10~15±0.2℃ and automatic humidity regulation.

2. The laboratory cryogenic radiation calibration device for aerospace optical remote sensing cameras according to claim 1, characterized in that, The wall panel (202) is made of black clean steel rock wool sandwich panel, which is used to reduce heat loss and isolate stray light interference to ensure calibration accuracy.

3. The laboratory cryogenic radiation calibration device for aerospace optical remote sensing cameras according to claim 1, characterized in that, The maintenance system also includes a purification door (201), which is designed to open outwards and is made of the same material as the wall panel (202). This door works together to achieve heat preservation inside and outside the device and to isolate stray light, thereby enhancing the convenience of maintenance and the protective effect.

4. A laboratory cryogenic radiation calibration device for aerospace optical remote sensing cameras according to claim 1, characterized in that, The glass window (203) is equipped with an automated lifting assembly to achieve controllable opening and closing, including a glass (301) that can slide up and down, a glass electric lift (302), a window counterweight (303) and a sliding guide rail (304). The glass (301) is embedded in the sliding guide rail (304) and is connected to the glass electric lift (302) and the window counterweight (303) respectively. It can achieve uniform speed lifting and partial / complete opening and closing through remote control.

5. A laboratory cryogenic radiation calibration device for aerospace optical remote sensing cameras according to claim 1, characterized in that, The temperature and humidity control system includes a refrigeration unit (401), an air conditioner (402), and an electric heater (403). The condenser end of the refrigeration unit (401) is connected to process cooling water, which provides a cold source to the calibration device through the refrigeration pipe (406); The air conditioner (402) is used to deliver cold air to the calibration device under the action of the cold source, and to adjust the temperature by adjusting the flow rate of the refrigerant water in the air conditioner (402). At the same time, the air conditioner (402) is connected to the condensate pipe (407) and the condensate water is discharged into the drain bucket (408) through the condensate pipe. The electric heater (403) is installed in the air supply duct (409) of the air conditioner (402) for fine-tuning the air supply temperature.

6. A laboratory cryogenic radiation calibration device for aerospace optical remote sensing cameras according to claim 5, characterized in that, The temperature and humidity control system also includes a supply and return air system (404) and a dehumidifier (405). The dehumidifier (405) is used to dehumidify the low-temperature radiation calibration device; The supply and return air system (404) is used to achieve airflow circulation.

7. A laboratory cryogenic radiation calibration device for aerospace optical remote sensing cameras according to claim 6, characterized in that, The dehumidifier (405) is turned on when the humidity is above 65% and turned off when it is below 50%.

8. A laboratory cryogenic radiation calibration device for aerospace optical remote sensing cameras according to claim 6, characterized in that, The low-temperature closed-loop control logic of the temperature and humidity control system is as follows: the temperature sensor in the device collects temperature data in real time, and the heating power of the electric heater and the cooling power of the refrigeration unit are dynamically adjusted through the algorithm. When the temperature is lower than the target range of 10~15℃, the electric heater is started to heat up and finely adjust the temperature; when the temperature is higher than the target range, the cold source supply is increased to cool down, so as to ensure that the outlet water temperature of the refrigeration unit is stable within ±0.2℃, and achieve precise and controllable low temperature.

9. A laboratory cryogenic radiometric calibration device for aerospace optical remote sensing cameras according to claim 8, characterized in that, The heating power of the electric heater and the cooling power of the refrigeration unit are dynamically adjusted by a fuzzy PID algorithm. The algorithm establishes a fuzzy rule base for temperature deviation and deviation change rate, and self-tunes the PID parameters to suppress thermal inertia overshoot. When the temperature is below the target range of 10~15℃, the electric heater is started to raise the temperature for fine adjustment; when the temperature is above the target range, the cold source supply is increased to lower the temperature, ensuring that the outlet water temperature of the refrigeration unit is stable within ±0.2℃, and achieving precise and controllable low temperature.

10. The calibration method implemented by the cryogenic radiation calibration device according to any one of claims 1-9, characterized in that, The methods include: A stable cubic frame is built by the structural system and an integrating sphere is installed. The light-shielding structure is formed by the maintenance system wall panels to cover the light outlet of the integrating sphere, and the purification door and glass window are closed to achieve full-enclosed light-shielding and heat preservation. The temperature and humidity control system is activated, and a fuzzy PID algorithm is used for closed-loop temperature control. Data is collected through temperature sensors, and temperature deviation and rate of change are calculated. The PID parameters are self-tuned to adjust the power of the electric heater and the chiller, so that the outlet water temperature of the chiller is stabilized within ±0.2℃. The dehumidifier controls humidity according to the threshold of 65% on and 50% off, and works with the supply and return air system to achieve uniform temperature and humidity distribution. After the temperature and humidity stabilize, the opening range of the glass is adjusted remotely through the automatic lifting component of the glass window to align the light output port of the integrating sphere with the equipment to be calibrated, and the integrating sphere is started to carry out calibration.

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