An on-board passive mid-and long-wave calibration system and method

Abstract

The application relates to a calibration system and method, in particular to a spaceborne passive middle-wave and long-wave calibration system and method; the purpose is to solve the problems of low energy efficiency, long time consumption and poor effect of the TEC refrigeration mode in the existing calibration system. The application comprises a support, a bearing mechanism and a radiation cover mounted on the support, a radiating plate connected with the radiation cover through a heat pipe, a support plate connected with the bearing mechanism, and a surface source black body; the radiating plate is arranged to face the space cold air and is used for heat dissipation through heat radiation; the heat pipe is used for forming a passive refrigeration link between the radiating plate and the radiation cover; the radiation cover is provided with a groove matched with the surface source black body, the surface source black body is arranged in the groove, and a gap exists between the surface source black body and the bottom surface of the groove. The application can utilize the space cold air to refrigerate the surface source black body, compared with the traditional TEC refrigeration mode, the satellite electric energy is not consumed, and the refrigeration effect is good and the refrigeration time consumption is short.

Description

Technical Field

[0001] This invention relates to a calibration system and method, specifically to an onboard passive mid-wave and long-wave calibration system and method. Background Technology

[0002] Onboard mid-wave and long-wave calibration refers to the radiometric calibration process of the mid-wave and long-wave infrared channels of an on-orbit remote sensing infrared camera (hereinafter referred to as an infrared camera). This process is fundamental to the quantitative analysis and application of remote sensing data and directly affects the accuracy and reliability of remote sensing observation data.

[0003] Currently, on-orbit calibration for mid-wave and long-wave infrared channels primarily relies on on-board blackbody calibration systems, supplemented by cold space calibration, and further validated through lunar calibration. The on-board blackbody calibration system, which involves installing a highly homogeneous blackbody inside the remote sensing camera and integrating it into the optical system during calibration, provides the camera with a radiation reference source of known temperature. This is currently the most mainstream and reliable calibration system.

[0004] For this type of calibration system, its performance largely depends on several key parameters of the blackbody: temperature control range, temperature uniformity, temperature accuracy, and temperature control rate. To meet the high-precision calibration requirements of the mid-wave infrared and long-wave infrared channels, the temperature control range of the blackbody needs to cover 220K to 360K, while also taking into account both the low-temperature and high-temperature calibration regions.

[0005] Currently, the realization of onboard blackbody cooling in the low-temperature region generally adopts TEC (Thermoelectric cooler) cooling method, which achieves active cooling of the blackbody based on the thermoelectric effect. For example, Chinese patent CN104133201A discloses an onboard calibration device based on a variable-temperature blackbody. However, this method has the following significant problems in practical spaceborne applications:

[0006] 1) Low energy efficiency ratio: The cooling process consumes a lot of electricity, and under the limited energy conditions on the satellite, it is difficult to support frequent cooling, which makes it impossible to achieve normalized calibration.

[0007] 2) Long time consumption: The cooling process is slow, which takes up a lot of the satellite's on-orbit operation time and seriously affects the efficiency of the main mission observation;

[0008] 3) Poor performance: As the temperature difference between the target temperature and the ambient temperature increases, the cooling efficiency drops sharply, making it difficult for the blackbody to reach the required deep low temperature state, which limits the lower limit of the calibration low temperature range.

[0009] In summary, existing on-board blackbody calibration systems based on TEC cooling have significant limitations in terms of energy efficiency, temperature range coverage, time consumption, and thermal management, severely restricting the efficient, high-precision, and routine application of on-board calibration systems. Therefore, there is an urgent need for a new type of calibration system that can meet the requirements of wide temperature range and high-precision calibration while significantly reducing energy consumption, shortening calibration time, and minimizing the thermal impact on the optical system. Summary of the Invention

[0010] The purpose of this invention is to solve the problems of low energy efficiency, long time consumption and poor effect of TEC cooling in existing calibration systems, and to provide a passive on-board mid-wave and long-wave calibration system and method.

[0011] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0012] A passive on-board mid-wave and long-wave calibration system, which is special in that:

[0013] It includes a support set on the main frame of the satellite, a load-bearing mechanism and a radiator installed on the support, a cooling plate connected to the radiator via a heat pipe, a support plate connected to the load-bearing mechanism, and a surface source blackbody;

[0014] The radiant cooling plate is positioned facing the cold space and is used to dissipate heat through thermal radiation; the heat pipe is used to form a passive cooling link between the radiant cooling plate and the radiant shield.

[0015] The radiation shield is provided with a groove adapted to the surface source blackbody, the surface source blackbody is placed in the groove, and there is a gap between the surface source blackbody and the bottom surface of the groove; multiple temperature sensors are arranged on the side surface of the surface source blackbody away from the bottom surface of the groove, and a multi-channel heating plate for heating the surface is attached; the side surface of the surface source blackbody away from the bottom surface of the groove is wrapped by the inner side of the heat insulation layer, and the outer side of the heat insulation layer is connected to the support plate.

[0016] The bearing mechanism is used to rotate the support plate, the surface source blackbody, and the insulation layer as a whole in the circumferential direction to the shooting position of the infrared camera during calibration, wherein the surface source blackbody with the side away from the multi-channel heating element faces the infrared camera.

[0017] Furthermore, the supporting mechanism includes a base, a drive motor, a rotating shaft, and a rotating housing;

[0018] The base is mounted on the support; the drive motor and the rotating shaft are both mounted inside the base, and the input end of the rotating shaft is connected to the output end of the drive motor; the output end of the rotating shaft is coaxially connected to the rotating housing, and the rotating housing is fitted onto the base; the support plate is mounted on the outer wall of the rotating housing; a first limiting member is provided on the inner wall of the rotating housing; at least one second limiting member is provided on the outer wall of the base, and the first and second limiting members together limit the circumferential rotation angle of the rotating housing relative to the base.

[0019] Furthermore, the multiple temperature sensors, multi-channel heating elements, and drive motors are all electrically connected to the satellite central control system.

[0020] Furthermore, the support is a three-layer hollow frame structure, and the support plate is a hollow structure.

[0021] Furthermore, the blackbody is rectangular in shape; the number of temperature sensors is seven, with four temperature sensors located at the four corners of the surface of the blackbody away from the bottom of the groove, and the remaining three temperature sensors being evenly distributed laterally in the middle of the surface of the blackbody away from the bottom of the groove.

[0022] Meanwhile, this invention also provides an on-board passive mid-wave and long-wave calibration method, which is characterized by employing the above-mentioned on-board passive mid-wave and long-wave calibration system and includes the following steps:

[0023] Step 1: After the satellite enters orbit, the radiant plate facing the cold space of space dissipates heat and cools down through thermal radiation. The radiant plate transfers the cold energy to the radiator through heat pipes, and then to the black body located in the groove through the radiator, so that the black body is in a low temperature state.

[0024] Step 2: Use multiple temperature sensors to detect the temperature of the blackbody in real time. When the temperature of the blackbody is lower than the critical operating temperature and the temperature difference between each temperature sensor is less than ±0.1K, the calibration low temperature zone is reached.

[0025] Step 3: Drive the surface source blackbody to rotate and unfold through the support mechanism, so that it reaches the shooting position of the infrared camera;

[0026] Step 4: Based on the feedback from the multiple temperature sensors, control the multi-channel heating element to heat the black body, so that it heats up sequentially and stabilizes precisely at multiple preset calibration temperature points. At each preset calibration temperature point, use an infrared camera to capture and record the image information of the black body for radiometric calibration.

[0027] Step 5: After calibration, the surface source blackbody is rotated and retracted into the groove of the radiation hood by the support mechanism; the heat of the surface source blackbody is transferred to the low-temperature radiation hood through thermal radiation, and then dissipated to the cold space through heat pipes and cooling plates to achieve passive recooling.

[0028] Furthermore, the critical operating temperature is 220K.

[0029] Compared with the prior art, the present invention has the following beneficial technical effects:

[0030] 1. The passive mid-wave and long-wave calibration system provided by this invention, wherein the combination of a radiant cooling plate, a heat pipe and a radiator can utilize the space-cooled air-to-surface blackbody for cooling. Compared with the traditional TEC cooling method, it does not consume the satellite's electrical energy and has a better cooling effect and shorter cooling time.

[0031] 2. The on-board passive mid-wave and long-wave calibration system provided by the present invention has multiple temperature sensors installed on the surface source blackbody. The cooperation of multiple temperature sensors and multiple heating elements can accurately and uniformly heat the surface source blackbody, which is beneficial to the calibration process.

[0032] 3. The on-board passive medium-wave and long-wave calibration system provided by this invention has a three-layer hollow frame structure for the support and a hollow structure for the support plate, which can effectively reduce the overall weight of the system and is beneficial to the launch and operation of the satellite.

[0033] 4. The passive mid-wave and long-wave calibration method provided by this invention utilizes the cold space in space for passive radiative cooling in the non-operating state, without consuming the satellite's electrical energy; while in the operating state, it uses a combination of multiple heating elements, insulation layers, and temperature sensors to precisely heat the blackbody source, which is beneficial for accurate calibration; after calibration is completed, the calibration system switches from the operating state to the non-operating state, and once again uses the cold space in space to passively radiate cool the blackbody source, so that its temperature is lower than the preset operating temperature, in preparation for the next calibration operation. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of the on-board passive mid-wave and long-wave calibration system of the present invention in its working mode.

[0035] Figure 2 This is a schematic diagram of the structure of the on-board passive mid-wave and long-wave calibration system of the present invention in non-operating mode;

[0036] Figure 3 This is a side view of the assembly of a surface source blackbody, a multi-channel heating element, and a thermal insulation layer in an embodiment of the on-board passive mid-wave and long-wave calibration system of the present invention.

[0037] Figure 4 This is a schematic diagram showing the installation position of the temperature sensor on the surface source blackbody in an embodiment of the on-board passive mid-wave and long-wave calibration system of the present invention.

[0038] The annotations in the attached figures are explained as follows:

[0039] 1-Surface source blackbody, 2-Radiation shield, 3-Heat pipe, 4-Bearing mechanism, 41-Base, 42-Rotating shell, 5-Cooling plate, 6-Multi-channel heating element, 7-Insulation layer, 8-Temperature sensor, 9-Support, 10-Support plate. Detailed Implementation

[0040] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0041] See Figures 1 to 4 This embodiment provides an on-board passive mid-wave and long-wave calibration system, including a support 9 set on the main frame of the satellite, a bearing mechanism 4 and a radiator 2 installed on the support 9, a cooling plate 5 connected to the radiator 2 through a heat pipe 3, a support plate 10 connected to the bearing mechanism 4, and a surface source blackbody 1 set on the support plate 10.

[0042] The radiant cooling plate 5 is positioned facing the cold space to dissipate heat through thermal radiation, forming a passive cooling link between the radiant cooling plate 5 and the radiant shield 2. The surface of the radiant cooling plate 5 is specially treated to have extremely high infrared emissivity, enabling it to continuously dissipate its heat into deep space through thermal radiation, thus maintaining a stable temperature (e.g., below 200K) for extended periods. The heat pipe 3 is a flexible or rigid vacuum tube with high thermal conductivity, filled with a working fluid. Its evaporation section is tightly connected to the radiant cooling plate 5, and its condensation section is tightly connected to the back or side wall of the radiant shield 2. This creates a highly efficient, passive cooling link with no moving parts between the radiant cooling plate 5 and the radiant shield 2, continuously transferring the cold energy collected by the radiant cooling plate 5 to the radiant shield 2.

[0043] The radiation shield 2 is provided with a groove adapted to the surface source blackbody 1. The surface source blackbody 1 is placed in the groove, and there is a gap between the surface source blackbody 1 and the bottom surface of the groove. Seven temperature sensors 8 are arranged on the side surface of the surface source blackbody 1 away from the bottom surface of the groove, and a multi-channel heating plate 6 for heating the surface is attached. The side surface of the surface source blackbody 1 away from the bottom surface of the groove is wrapped by the inner side of the heat insulation layer 7, and the outer side of the heat insulation layer 7 is connected to the support plate 10.

[0044] The bearing mechanism 4 is used to rotate the support plate 10, the surface source blackbody 1, and the insulation layer 7 as a whole circumferentially to the shooting position of the infrared camera during calibration, wherein the surface of the surface source blackbody 1 away from the multi-channel heating element 6 faces the infrared camera. Specifically, the bearing mechanism 4 includes a base 41, a drive motor, a rotating shaft, and a rotating housing 42; the base 41 is mounted on the support 9; the drive motor and the rotating shaft are both mounted inside the base 41, and the input end of the rotating shaft is connected to the output end of the drive motor; the output end of the rotating shaft is coaxially connected to the rotating housing 42, and the rotating housing 42 is sleeved on the base 41; the support plate 10 is mounted on the outer wall of the rotating housing 42; a first limiting member (protrusion) is provided on the inner wall of the rotating housing 42; two second limiting members (protrusions) are provided on the outer wall of the base 41, and the first and second limiting members are used together to limit the circumferential rotation angle of the rotating housing 42 relative to the base 41.

[0045] The seven temperature sensors 8, the multi-channel heating element 6, and the drive motor are all electrically connected to the satellite central control system. The surface source blackbody 1 is rectangular in shape. Four temperature sensors 8 are located at the four corners of the surface surface of the surface source blackbody 1 away from the bottom of the groove, and the remaining three temperature sensors 8 are evenly distributed laterally in the middle of the surface surface of the surface source blackbody 1 away from the bottom of the groove. This arrangement aims to comprehensively sense the two-dimensional temperature field of the surface of the surface source blackbody 1, providing direct data for evaluating and controlling temperature uniformity.

[0046] Support 9 is a three-layer hollow frame structure, and support plate 10 is a hollow structure. This design is conducive to reducing the overall weight of the satellite.

[0047] Meanwhile, this embodiment also provides an on-board passive mid-wave and long-wave calibration method, which uses the above-mentioned on-board passive mid-wave and long-wave calibration system and includes the following steps:

[0048] Step 1: After the satellite enters orbit, the radiant plate 5 facing the cold space of space dissipates heat and cools down through thermal radiation. The radiant plate 5 transfers the cold energy to the radiator 2 through the heat pipe 3, and then to the surface source blackbody 1 located in the groove through the radiator 2, so that the surface source blackbody 1 is in a low temperature state.

[0049] Step 2: Use seven temperature sensors 8 to detect the temperature of the surface source blackbody 1 in real time. When the temperature of the surface source blackbody 1 is lower than the critical operating temperature (usually 220K~360K, 220K in this embodiment), and the temperature difference between each temperature sensor 8 is less than ±0.1K, the calibration low temperature zone is reached.

[0050] Step 3: Drive the surface source blackbody 1 to rotate and unfold (in this embodiment, rotate 90°) through the support mechanism 4, so that it reaches the shooting position of the infrared camera;

[0051] Step 4: Based on the feedback from the seven temperature sensors 8, control the multi-channel heating element 6 to heat the blackbody 1, so that it heats up sequentially and stabilizes precisely at multiple preset calibration temperature points (e.g., 220K, 260K, 300K, 340K). At each preset calibration temperature point, use an infrared camera to capture and record the image information of the blackbody 1, thereby establishing a quantitative relationship between the digital signal output by the infrared camera detector and the known absolute radiance (corresponding to the temperature of the blackbody 1), and performing radiometric calibration.

[0052] Step 5: After calibration, the bearing mechanism 4 drives the surface source blackbody 1 to rotate and retract into the groove of the radiation shield 2; the heat of the surface source blackbody 1 is transferred to the low-temperature radiation shield 2 through thermal radiation, and then dissipated to the cold space through the heat pipe 3 and the cooling plate 5, realizing passive recooling.

[0053] Compared to the traditional TEC cooling method, this embodiment does not consume the satellite's electrical energy and has a better cooling effect and shorter cooling time.

Claims

1. A passive on-board mid-wave and long-wave calibration system, characterized in that: It includes a support (9) set on the main frame of the satellite, a load-bearing mechanism (4) and a radiation shield (2) installed on the support (9), a cooling plate (5) connected to the radiation shield (2) through a heat pipe (3), a support plate (10) connected to the load-bearing mechanism (4), and a surface source blackbody (1). The radiant cooling plate (5) is set facing the cold space and is used to dissipate heat through thermal radiation; the heat pipe (3) is used to form a passive cooling link between the radiant cooling plate (5) and the radiant shield (2); The radiation shield (2) is provided with a groove adapted to the surface source blackbody (1), the surface source blackbody (1) is placed in the groove, and there is a gap between the surface source blackbody (1) and the bottom surface of the groove; multiple temperature sensors (8) are arranged on the side surface of the surface source blackbody (1) away from the bottom surface of the groove, and a multi-channel heating plate (6) for heating the surface is attached; the side surface of the surface source blackbody (1) away from the bottom surface of the groove is wrapped by the inner side of the heat insulation layer (7), and the outer side of the heat insulation layer (7) is connected to the support plate (10); The bearing mechanism (4) is used to drive the support plate (10), the surface source blackbody (1) and the insulation layer (7) to rotate as a whole in the circumferential direction to the shooting position of the infrared camera during calibration, wherein the surface source blackbody (1) has its side surface away from the multi-channel heating plate (6) facing the infrared camera.

2. The on-board passive mid-wave and long-wave calibration system according to claim 1, characterized in that: The bearing mechanism (4) includes a base (41), a drive motor, a rotating shaft, and a rotating housing (42). The base (41) is mounted on the support (9); the drive motor and the rotating shaft are both mounted inside the base (41), and the input end of the rotating shaft is connected to the output end of the drive motor; the output end of the rotating shaft is coaxially connected to the rotating housing (42), and the rotating housing (42) is mounted on the base (41); the support plate (10) is mounted on the outer wall of the rotating housing (42); a first limiting member is mounted on the inner wall of the rotating housing (42); at least one second limiting member is mounted on the outer wall of the base (41), and the first and second limiting members are used together to limit the circumferential rotation angle of the rotating housing (42) relative to the base (41).

3. The on-board passive mid-wave and long-wave calibration system according to claim 2, characterized in that: The multiple temperature sensors (8), the multi-channel heating element (6), and the drive motor are all electrically connected to the satellite central control system.

4. The on-board passive mid-wave and long-wave calibration system according to any one of claims 1 to 3, characterized in that: The support (9) is a three-layer hollow frame structure, and the support plate (10) is a hollow structure.

5. The on-board passive mid-wave and long-wave calibration system according to claim 4, characterized in that: The surface source blackbody (1) is rectangular in shape; the number of temperature sensors (8) is seven, of which four temperature sensors (8) are located at the four corners of the surface of the surface source blackbody (1) away from the bottom of the groove, and the remaining three temperature sensors (8) are evenly distributed laterally in the middle of the surface of the surface source blackbody (1) away from the bottom of the groove.

6. A passive on-board mid-wave and long-wave calibration method, characterized in that, The on-board passive mid-wave and long-wave calibration system according to any one of claims 1 to 5 includes the following steps: Step 1: After the satellite enters orbit, the radiant plate (5) facing the cold space of space cools down by heat radiation, and the radiant plate (5) transfers the cold energy to the radiator (2) through the heat pipe (3), and then to the surface source blackbody (1) located in the groove through the radiator (2), so that the surface source blackbody (1) is in a low temperature state. Step 2: Use multiple temperature sensors (8) to detect the temperature of the surface source blackbody (1) in real time. When the temperature of the surface source blackbody (1) is lower than the critical working temperature and the temperature difference between each temperature sensor (8) is less than ±0.1K, the calibration low temperature zone is reached. Step 3: Drive the surface source blackbody (1) to rotate and unfold through the support mechanism (4) so ​​that it reaches the shooting position of the infrared camera; Step 4: Based on the feedback from the multiple temperature sensors (8), control the multi-channel heating element (6) to heat the black body (1) in sequence, so that it heats up and stabilizes at multiple preset calibration temperature points. At each preset calibration temperature point, use an infrared camera to capture and record the image information of the black body (1) for radiation calibration. Step 5: After calibration, the surface source blackbody (1) is rotated and retracted into the groove of the radiation shield (2) by the bearing mechanism (4); the heat of the surface source blackbody (1) is transferred to the low-temperature radiation shield (2) through thermal radiation, and then dissipated to the cold space through the heat pipe (3) and the cooling plate (5) to achieve passive recooling.

7. The on-board passive mid-wave and long-wave calibration method according to claim 6, characterized in that: The critical operating temperature is 220K.

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