Ultra-low temperature vacuum infrared radiometer based on shutter modulation principle

Abstract

The application provides an ultra-low temperature vacuum infrared radiometer based on a shutter modulation principle, comprising a modulation component, an optical-mechanical structure, an infrared detector and an electronic component; the modulation component is arranged between a device to be measured and the optical-mechanical structure, and comprises a shutter modulator and a shutter baffle; the shutter modulator controls the shutter baffle to move at a fixed frequency and intermittently shields the radiation energy transmission of the device to be measured; the optical-mechanical structure is used for converging the radiation energy; and the infrared detector and the electronic component are used for quantitatively collecting and processing the radiation energy. The modulation component is arranged outside the optical-mechanical structure of the radiometer to replace a chopper, so that the thermal influence of the modulation system on the system is reduced.

Description

Technical Field

[0001] This invention belongs to the field of infrared radiation technology, specifically relating to an ultra-low temperature vacuum infrared radiometer based on the shutter modulation principle. Background Technology

[0002] With the development of infrared technology, its application has expanded to near-space and outer space, primarily used in infrared remote sensing systems, space reconnaissance systems, and near-space early warning systems. Infrared payloads are crucial equipment used in infrared reconnaissance, early warning, and remote sensing. Before launch, infrared payloads undergo ground-based radiometric calibration experiments to refine their design and reduce iterations. Infrared payload performance testing equipment is a key component in these calibration experiments. This equipment can simulate targets observed by the infrared payload in orbit, such as buildings, natural landscapes, space satellites, and space stations. These targets operate at extremely low temperatures, resulting in very weak infrared radiation. Under normal temperature conditions, this weak infrared radiation would be overwhelmed by stray radiation and the optical system's own thermal radiation, making it impossible to detect. Therefore, the infrared payload performance testing equipment must operate in an environment identical to that of orbital space, i.e., a vacuum and cryogenic environment.

[0003] To ensure the accuracy of the output radiation values ​​of the cryogenic infrared load performance testing equipment, a precise ultra-weak infrared radiation measurement system is needed for calibration, with its operating environment identical to that of the equipment. Current calibration methods use a cryogenic vacuum blackbody as a standard and an infrared radiometer as a value transfer device to transmit the values ​​to the cryogenic infrared load performance testing equipment, which then performs performance parameter testing on the cryogenic infrared load. Currently, most cryogenic vacuum infrared radiometers use vacuum choppers as signal modulation devices. However, vacuum choppers need to operate continuously in ultra-low temperature environments, and the chopper blades continuously generate heat during modulation. This heat radiation cannot be extracted from the radiometer itself. Although temperature control and acquisition of the rotating blades are possible, the accuracy is only 0.1℃, which cannot meet the requirements for high-precision cryogenic infrared radiation value transfer, leading to significant measurement errors in weak signal detection. Therefore, it is necessary to design an ultra-weak infrared radiometer for cryogenic vacuum environments to calibrate the radiation energy of cryogenic infrared loads in space environments. Summary of the Invention

[0004] The purpose of this invention is to provide an ultra-low temperature vacuum infrared radiometer based on the shutter modulation principle, which solves the technical problem that existing infrared radiometers cannot meet the requirements for ultra-low temperature weak infrared load radiation calibration.

[0005] To achieve the above objectives, this invention provides a cryogenic vacuum infrared radiometer based on the shutter modulation principle, comprising a modulation component, an optomechanical structure, an infrared detector, and electronic components. The modulation component, placed between the device under test and the optomechanical structure, includes a shutter modulator and a shutter baffle. The shutter modulator controls the shutter baffle to move at a fixed frequency, intermittently blocking the transmission of radiant energy from the device under test. The optomechanical structure is used to converge radiant energy. The infrared detector and electronic components are used for quantitative acquisition and processing of radiant energy.

[0006] Furthermore, the shutter modulator includes a support frame, a switching guide rail, a slider, a transmission link, and a control motor; the switching guide rail is horizontally mounted on the support frame, and the slider is mounted on the switching guide rail; the control motor is mounted on the support frame, and the control motor drives the slider to perform horizontal reciprocating motion along the switching guide rail through the transmission link; the shutter baffle is vertically mounted on the slider of the shutter modulator.

[0007] Furthermore, the support frame includes a vertical plate, the control motor is mounted on the back of the vertical plate and the control motor shaft passes vertically through the vertical plate, and the switching guide rail is horizontally mounted on the front of the vertical plate; the transmission linkage includes a short linkage and a long linkage, one end of the short linkage and the long linkage are stacked and connected by a pin, the two linkages can rotate relative to the pin, the free end of the short linkage is connected to the control motor shaft, and the free end of the long linkage is fixed to the slider.

[0008] Furthermore, the slider and the upper and lower edges of the switching guide rail are engaged by a slot; a heat insulation block is installed between the shutter baffle and the slider; the control motor is a high and low temperature stepper motor, and the control motor is wrapped with a double-layer heat insulation shielding film.

[0009] Furthermore, the shutter baffle includes a radiating plate with an internal cavity, and a refrigerant inlet and outlet connected to the internal cavity on the radiating plate; the surface of the radiating plate is coated with a high emissivity coating of ultra-black material, and a microcone structure is provided on the side of the radiating plate near the optomechanical structure.

[0010] Furthermore, the optomechanical structure is integrally housed within a housing, with cooling pipes coiled around the outside of the housing.

[0011] Furthermore, the optomechanical structure includes a primary reflector, a secondary reflector, an Invar connecting rod, a housing, and cooling pipes; the primary reflector and the secondary reflector are respectively mounted inside the housing via support bases, and the support bases of the primary reflector and the secondary reflector are connected by an Invar connecting rod; the primary reflector is used to converge incident energy, and the secondary reflector is used to deflect the light path; the housing has a radiation inlet on the side near the shutter baffle, and cooling pipes are coiled around the outside of the housing, with refrigerant inlets and outlets reserved in the cooling pipes.

[0012] Furthermore, the infrared detector is installed in the emission direction of the optomechanical structure and includes a detector surface, a cooling connecting rod, a detector cooler, a detector support frame, and a detector support base. The detector surface is arranged inside the housing and is used to receive the light emitted from the secondary reflector. The detector surface is fixed to one end of the cooling connecting rod, and the other end of the cooling connecting rod passes through the housing and is installed on the detector cooler. The detector cooler is installed on the support base through the support frame, and the detector support base and the secondary reflector support base are connected by an Invar connecting rod.

[0013] Furthermore, the modulation component, optomechanical structure, and infrared detector are all housed within the vacuum cold chamber, while the electronic components are located outside the vacuum cold chamber. The shutter baffle includes a radiating plate with an internal cavity, and a refrigerant inlet / outlet connected to the internal cavity is provided on the radiating plate. The optomechanical structure is housed within a housing, and a cooling pipeline is coiled around the outside of the housing. A liquid nitrogen tank is located outside the vacuum cold chamber, and the liquid nitrogen tank is connected to the refrigerant inlet / outlet of the shutter baffle and the refrigerant inlet / outlet of the cooling pipeline of the optomechanical structure.

[0014] This invention also provides a method for testing cryogenic vacuum infrared radiometers based on the shutter modulation principle. Using the aforementioned cryogenic vacuum infrared radiometer, the testing method includes the following steps:

[0015] The shutter baffle is used as a standard blackbody to control its stability at the first temperature;

[0016] The shutter is controlled to modulate at a first fixed frequency, and the corresponding voltage signal value is collected.

[0017] Adjust the shutter baffle to stabilize at the nth temperature, where n≥2, and repeat the above process to complete the calibration;

[0018] Align the cryogenic vacuum infrared radiometer with the device under test and align its optical axis with the optical axis of the device under test;

[0019] The device under test has completed its power-on preheating and stabilized at a certain temperature;

[0020] The shutter baffle is modulated at a second fixed frequency, and the temperature of the shutter baffle is monitored until it stabilizes.

[0021] The voltage signal value of the device under test is collected, and the voltage signal value is converted into a radiation temperature value according to the calibration result to complete the test of the device under test.

[0022] The beneficial effects of this invention compared to the prior art are as follows:

[0023] (1) The present invention places the modulation component outside the radiometer optomechanical structure to replace the chopper. At the same time, the radiometer optomechanical structure is wrapped with liquid nitrogen pipeline for secondary cooling, which greatly reduces the thermal impact of the modulation system on the system.

[0024] (2) The baffle of the modulation component is designed with a microcone structure and sprayed with a high emissivity coating. The internal design is an integral liquid nitrogen chamber to improve its emissivity and temperature measurement accuracy, and further improve the sensitivity and dynamic range of the system.

[0025] (3) The modulation component has a simple structure, is easy to control, and has low processing cost. Attached Figure Description

[0026] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0027] Figure 1 A schematic diagram of the structure of an ultra-low temperature vacuum infrared radiometer provided in a specific embodiment of the present invention;

[0028] Figure 2 A schematic diagram of the modulation component structure provided in a specific embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the optomechanical structure of an ultra-low temperature vacuum infrared radiometer provided in a specific embodiment of the present invention.

[0030] The above figures include the following reference numerals:

[0031] 1. Baffle; 2. Transmission connecting rod; 3. Support frame; 4. Base plate; 5. Detector cooler; 6. Detector support frame; 7. Detector cooler connecting rod; 8. Housing; 9. Radiometer liquid nitrogen pipeline outlet; 10. Radiometer liquid nitrogen pipeline inlet; 11. Control motor; 12. Baffle liquid nitrogen inlet; 13. Baffle liquid nitrogen outlet; 14. Heat insulation block; 15. Switching guide rail; 16. Primary reflector; 17. Primary reflector support base; 18. Secondary reflector; 19. Secondary reflector support base; 20. Invar connecting rod; 21. Detector surface; 22. Detector support base. Detailed Implementation

[0032] Specific embodiments of the present invention will now be described in detail. In the following description, specific details are set forth for purposes of explanation and not limitation, in order to aid in a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced in other embodiments departing from these specific details.

[0033] It should be noted that, in order to avoid obscuring the invention with unnecessary details, only the device structure and / or processing steps closely related to the solution of the invention are shown in the accompanying drawings, while other details that are not closely related to the invention are omitted.

[0034] Existing ultra-low temperature weak infrared signal processing technologies mainly employ choppers. Choppers need to operate continuously in ultra-low temperature environments, and their own thermal radiation cannot be dissipated within the radiometer. Furthermore, the temperature of the chopper plate cannot be precisely controlled or measured, leading to significant measurement errors in the detection of weak signals. To address these issues, this invention replaces the chopper by placing a modulation component outside the radiometer's optomechanical structure. The entire optomechanical structure is encased in liquid nitrogen tubing for secondary cooling, significantly reducing the thermal impact of the modulation system. Additionally, a specially designed baffle improves its emissivity and temperature measurement accuracy, further enhancing the system's sensitivity and dynamic range.

[0035] This invention provides a cryogenic vacuum infrared radiometer based on the shutter modulation principle, comprising a modulation component, an optomechanical structure, an infrared detector, and electronic components. The modulation component, placed between the device under test (DUT) and the optomechanical structure, includes a shutter modulator and a shutter baffle. The shutter modulator controls the shutter baffle to move at a fixed frequency, intermittently blocking the radiant energy transfer from the DUT. The optomechanical structure is used to focus the radiant energy. The infrared detector and electronic components are used for quantitative acquisition and processing of the radiant energy. Placing the modulation component outside the radiometer's optomechanical structure, replacing the chopper, reduces the thermal impact of the modulation system on the system.

[0036] Furthermore, the shutter modulator includes a support frame, a switching guide rail, a slider, a transmission link, and a control motor. The switching guide rail is horizontally mounted on the support frame, and the slider is mounted on the switching guide rail. The control motor is mounted on the support frame and drives the slider to perform horizontal reciprocating motion along the switching guide rail via the transmission link. The shutter baffle is vertically mounted on the slider of the shutter modulator. The shutter modulator controls the movement frequency of the shutter baffle by selecting the motor frequency.

[0037] Furthermore, the support frame includes a vertical plate, a control motor mounted on the back of the vertical plate with its shaft passing vertically through it, and a switching guide rail horizontally mounted on the front of the vertical plate. The transmission linkage includes a short link and a long link, with one end of each link stacked and connected by a pin. The two links can rotate relative to the pin. The free end of the short link is connected to the control motor shaft, and the free end of the long link is fixed to the slider. The transmission linkage converts the motor rotation into the horizontal movement of the slider.

[0038] Furthermore, the shutter baffle includes a radiating plate with an internal cavity, and a refrigerant inlet and outlet on the radiating plate that connect to the internal cavity. Since the cavity is evenly distributed inside the shutter baffle, during operation, the entire cavity is circulated with a refrigerant such as liquid nitrogen, which can quickly achieve thermal equilibrium and control the low temperature of the shutter baffle.

[0039] Furthermore, a high-emissivity coating of ultra-black material is sprayed onto the surface of the radiating plate, and a microconical structure is set on the side of the radiating plate near the optomechanical structure. This design can improve the emissivity of the shutter, reduce environmental impact, and enable it to serve as a standard blackbody for calibrating the device under test.

[0040] Furthermore, the entire optomechanical structure is housed within a casing, with cooling pipes coiled around the outside of the casing to provide secondary cooling for the optomechanical structure and reduce the thermal impact.

[0041] The present invention will now be described in detail with reference to a specific embodiment.

[0042] like Figure 1 As shown, this invention provides a cryogenic vacuum infrared radiometer based on the shutter modulation principle, including a modulation component, an infrared radiometer optomechanical structure, an infrared detector, and back-end electronic components. The modulation component includes a shutter modulator and a shutter baffle. The shutter modulator controls the shutter baffle to move at a fixed frequency, intermittently blocking the radiation transmission of the device under test, enabling modulation of the shutter baffle at a fixed frequency; the shutter baffle can also serve as a standard blackbody for precise calibration of cryogenic infrared radiation energy. The infrared radiometer optomechanical structure focuses the radiation energy. The infrared detector and electronic components enable quantitative acquisition of the radiation energy.

[0043] like Figure 2 As shown, the shutter modulator includes a support frame 3, a control motor 11, a switching guide rail 15, a slider, and a transmission link 2. A vertical plate is mounted on the support frame 3. The control motor 11 is mounted on the back of the vertical plate, with its shaft passing vertically through the plate. The switching guide rail 15 is a long strip structure, horizontally mounted on the front of the vertical plate. The slider is mounted on the switching guide rail 15 and can move horizontally back and forth along it. The transmission link 2 includes a short link and a long link. One end of the short link and the long link are stacked and connected by a pin. The two links can rotate relative to the pin. The free end of the short link is fixed to the control motor shaft, and the free end of the long link is fixed to the slider. The rotation of the control motor drives the transmission link to move the slider horizontally along the switching guide rail 15.

[0044] In this embodiment, the slider and the upper and lower edges of the switching guide rail 15 are engaged by slots, which is simple and easy to manufacture. The control motor 11 is a high and low temperature stepper motor, which can operate normally at liquid nitrogen temperature. Its power is in the milliwatt range during operation, and a double-layer heat-insulating shielding film is wrapped around the control motor to minimize its radiation impact. The motor drives the transmission linkage 2 to achieve frequency modulation from 0Hz to 10Hz.

[0045] like Figure 2 As shown, the shutter baffle 1 is vertically mounted on the slider of the shutter modulator. To avoid temperature effects, a heat insulation block 14 is installed between the shutter baffle 1 and the slider.

[0046] Shutter baffle 1 includes a radiating plate, a liquid nitrogen inlet 12, and a liquid nitrogen outlet 13. The interior of the radiating plate is a liquid nitrogen chamber. The liquid nitrogen inlet 12 and the liquid nitrogen outlet 13 are mounted on the radiating plate and communicate with the liquid nitrogen chamber. The surface of the radiating plate is coated with a high-emissivity ultra-black material, achieving an emissivity of over 0.98. The side of the radiating plate near the optomechanical structure adopts a micro-conical structure, i.e., it is equipped with several small conical protrusions to increase emissivity and reduce environmental impact. To monitor the operating temperature of shutter baffle 1 in real time, a platinum resistance thermometer is also installed on shutter baffle 1. A Pt100 platinum resistance thermometer is used, with a temperature measurement accuracy of 0.01℃.

[0047] The liquid nitrogen chamber is evenly distributed inside the baffle. During normal operation, liquid nitrogen is diverted from the liquid nitrogen in the infrared radiometer. Under a fixed flow rate, the liquid nitrogen can achieve thermal equilibrium within a certain period of time.

[0048] like Figure 1 , 3As shown, the optomechanical structure of the infrared radiometer is located between the modulation assembly and the infrared detector, and includes a primary reflector 16, a secondary reflector 18, an Invar connecting rod 20, a housing 8, a liquid nitrogen pipeline, and other optomechanical structural components. The primary reflector 16 can focus the incident energy; the secondary reflector 18 can fold the light path in the optical path, improving the space utilization of the system; the primary reflector 16 and the secondary reflector 18 are installed in the housing 8 through the primary reflector support base 17 and the secondary reflector support base 19 (the primary reflector 16 and the secondary reflector 18 are installed on the bottom plate of the housing 8 through the support base), and an Invar connecting rod 20 is placed between the primary reflector support base 18 and the secondary reflector support base 14. Since Invar has a low coefficient of linear expansion, it will not affect the spatial spacing of the optical path when the temperature changes are wide; the housing 8 has a radiation inlet on the side near the shutter baffle 1; the liquid nitrogen pipeline is coiled on the housing 8, with a reserved inlet 10 and outlet 9 for the radiometer liquid nitrogen pipeline. The liquid nitrogen pipeline is coiled according to the shape of the radiometer, which can realize the overall cooling of the radiometer and ensure the high sensitivity of the system. In this embodiment, two sets of liquid nitrogen pipelines are coiled on the plate surface of the housing 8 without radiation inlet, one set is coiled on the back plate, and the other set is coiled on the top plate, bottom plate and side plate.

[0049] like Figure 3 As shown, the infrared detector is installed in the emission direction of the infrared radiometer's optomechanical structure and includes a detector surface 21, a cooling connecting rod 7, a detector cooler 5, a detector support frame 6, and a detector support base 22. The detector surface 21 is arranged inside the housing 8 and is used to receive the light reflected by the secondary reflector 18. The detector surface 21 is fixed to one end of the cooling connecting rod 7, and the other end of the cooling connecting rod 7 passes through the radiometer housing 8 and is mounted on the detector cooler 5. The detector cooler 5 is mounted on the detector support base 22 via the detector support frame 6. The detector support base 22 is connected to the secondary reflector support base 19 via an Invar connecting rod.

[0050] In this embodiment, the infrared detector is a long-wavelength point source infrared detector with a detector surface size of 0.7mm × 0.7mm and a detectivity of 5 × 10¹⁰ cmHz¹ / ²W⁻¹. The detector cooler 5 is a Stirling cooler, which can cool the infrared detector without adding liquid nitrogen according to the Stirling electric cooling principle, ensuring its normal operation.

[0051] In this embodiment, the modulation component, the infrared radiometer optomechanical structure, and the infrared detector are mounted on the base plate 4 and are housed as a whole in the vacuum cold chamber. The liquid nitrogen tank is located outside the vacuum cold chamber and is connected to the baffle liquid nitrogen inlet 12, the baffle liquid nitrogen outlet 13, the radiometer liquid nitrogen inlet 10, and the radiometer liquid nitrogen outlet 9 via flanges.

[0052] The electronic components are located outside the vacuum cold chamber and include a preamplifier and a lock-in amplifier. The preamplifier amplifies the radiation energy detected by the infrared detector to improve the system's signal-to-noise ratio. The lock-in amplifier, based on lock-in amplification theory, detects weak signals at the reference frequency for quantitative analysis.

[0053] In this embodiment, the technical specifications of the cryogenic vacuum infrared radiometer are as follows:

[0054] Operating wavelength: 8μm~12μm

[0055] Detection temperature range: 140K~410K

[0056] Casing radiation inlet diameter: 80mm

[0057] Primary mirror focal length: 250mm

[0058] Sensitivity: 0.03K

[0059] The radiation panel has a radiation surface size of 90mm × 90mm.

[0060] The aforementioned cryogenic vacuum infrared radiometer utilizes a shutter modulator, employing a motor and transmission mechanism to achieve fixed-frequency modulation of the shutter baffle. Operating in liquid nitrogen, the shutter baffle can reach temperatures below 120K, and its precise temperature can be obtained through measurement with a platinum resistance thermometer. The radiation plate, through structural design and coating, achieves high emissivity. The optomechanical structure of the infrared radiometer ensures that the overall system remains relatively stable even at low ambient temperatures, enhancing system stability. After receiving radiant energy, the infrared detector processes the received energy using a preamplifier and lock-in amplifier based on the principle of weak signal modulation, achieving quantitative acquisition of the radiant energy.

[0061] The calibration method for the cryogenic vacuum infrared radiometer based on the shutter modulation principle described above is as follows:

[0062] 1. Use a vacuum low-temperature standard blackbody as a measurement transfer standard, set it to a certain temperature, and wait for it to stabilize;

[0063] 2. Align the ultra-low temperature vacuum infrared radiometer with the vacuum low temperature standard blackbody radiation outlet, and make its optical axis coincide with the central axis of the vacuum low temperature standard blackbody radiation outlet, with a distance of 10cm.

[0064] 3. The shutter baffle of the ultra-low temperature vacuum infrared radiometer is modulated at a frequency of 4Hz, and the temperature of the baffle is monitored until it stabilizes;

[0065] 4. By acquiring the current voltage signal value using an ultra-low temperature vacuum infrared radiometer detector, the voltage signal value corresponding to the current standard radiation temperature can be determined.

[0066] 5. Set the vacuum cryogenic standard blackbody to another temperature value, wait for its temperature to stabilize, and repeat steps 1 to 4 to complete the calibration of the cryogenic vacuum infrared radiometer.

[0067] Using the above method, high-precision calibration of the cryogenic vacuum infrared radiometer can be achieved by selecting a high-precision vacuum cryogenic standard blackbody. When high calibration accuracy is not required, a shutter baffle can also be used directly as the standard blackbody, controlled to be stable at a certain temperature, and monitored by a platinum resistance thermometer; the shutter baffle is controlled to be modulated at a fixed frequency; the current voltage signal value is collected; the shutter baffle temperature is adjusted, the above process is repeated, and the corresponding voltage signal is collected to achieve calibration.

[0068] The detection process of the cryogenic vacuum infrared radiometer based on the shutter modulation principle is as follows:

[0069] 1. Align the cryogenic vacuum infrared radiometer with the device under test, ensuring its optical axis coincides with the optical axis of the device under test at a distance of 10cm.

[0070] 2. The device under test completes power-on preheating and stabilizes at a certain temperature;

[0071] 3. The shutter baffle of the ultra-low temperature vacuum infrared radiometer is modulated at a frequency of 4Hz, and the temperature of the baffle is monitored until it stabilizes;

[0072] 4. The voltage signal value of the device under test is collected by the ultra-low temperature vacuum infrared radiometer detector. Based on the calibration results, the voltage signal value is converted into a radiation temperature value to complete the test of the device under test.

[0073] This invention employs a vacuum cryogenic shutter baffle, which can precisely control the temperature of the shutter baffle with an accuracy of 0.01℃ and can cool it to very low temperatures, with a minimum temperature of 80K. Combined with a shutter regulator for frequency modulation, the shutter baffle can replace the chopper to achieve the detection and calibration of ultra-weak infrared radiation signals.

[0074] The features described and / or illustrated above with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, and / or in combination with or in lieu of features in other embodiments.

[0075] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, whole, step, or component, but does not exclude the presence or addition of one or more other features, wholes, steps, components, or combinations thereof.

[0076] Many features and advantages of these embodiments are apparent from this detailed description, and therefore the appended claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. Furthermore, since many modifications and alterations will readily occur to those skilled in the art, the embodiments of the invention are not intended to be limited to the precise structures and operations illustrated and described, but rather to encompass all suitable modifications and equivalents falling within their scope.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0078] The parts of this invention not described in detail are techniques known to those skilled in the art.

Claims

1. A cryogenic vacuum infrared radiometer based on the shutter modulation principle, characterized in that, It includes a modulation component, an optomechanical structure, an infrared detector, and electronic components. The modulation component, placed between the device under test (DUT) and the optomechanical structure, includes a shutter modulator and a shutter baffle. The shutter modulator controls the shutter baffle to move at a fixed frequency, intermittently blocking the transmission of radiated energy from the DUT. The optomechanical structure is used to converge radiated energy. The infrared detector and electronic components are used to quantitatively acquire and process radiated energy. The entire optomechanical structure is housed within a housing, with a radiation entrance located on the side of the housing near the shutter baffle, and the modulation component is placed outside the optomechanical structure. The shutter modulator includes a support frame, a switching guide rail, a slider, a transmission link, and a control motor; the switching guide rail is horizontally mounted on the support frame, and the slider is mounted on the switching guide rail; the control motor is mounted on the support frame, and the control motor drives the slider to perform horizontal reciprocating motion along the switching guide rail through the transmission link; the shutter baffle is vertically mounted on the slider of the shutter modulator.

2. The cryogenic vacuum infrared radiometer according to claim 1, characterized in that, The support frame includes a vertical plate, the control motor is mounted on the back of the vertical plate and the control motor shaft passes vertically through the vertical plate, and the switching guide rail is horizontally mounted on the front of the vertical plate; the transmission linkage includes a short linkage and a long linkage, one end of the short linkage and the long linkage are stacked and connected by a pin, the two linkages can rotate relative to the pin, the free end of the short linkage is connected to the control motor shaft, and the free end of the long linkage is fixed to the slider.

3. The cryogenic vacuum infrared radiometer according to claim 1, characterized in that, The slider and the upper and lower edges of the switching guide rail are engaged by a slot; a heat insulation block is installed between the shutter baffle and the slider; the control motor is a high and low temperature stepper motor, and the control motor is wrapped with a double-layer heat insulation shielding film.

4. The cryogenic vacuum infrared radiometer according to claim 1, characterized in that, The shutter baffle includes a radiating plate with an internal cavity, and a refrigerant inlet and outlet connected to the internal cavity on the radiating plate; the surface of the radiating plate is coated with a high emissivity coating of ultra-black material, and a microcone structure is provided on the side of the radiating plate near the optomechanical structure.

5. The cryogenic vacuum infrared radiometer according to claim 1, characterized in that, The outer casing is surrounded by cooling pipes.

6. The cryogenic vacuum infrared radiometer according to claim 5, characterized in that, The optomechanical structure includes a primary reflector, a secondary reflector, an Invar connecting rod, a housing, and cooling pipes. The primary reflector and the secondary reflector are respectively mounted inside the housing via support bases. The support bases of the primary reflector and the secondary reflector are connected by an Invar connecting rod. The primary reflector is used to converge incident energy, and the secondary reflector is used to deflect the light path. Cooling pipes are coiled around the outside of the housing, and the cooling pipes have reserved refrigerant inlets and outlets.

7. The cryogenic vacuum infrared radiometer according to claim 1, characterized in that, The infrared detector is installed in the emission direction of the optomechanical structure and includes a detector surface, a cooling connecting rod, a detector cooler, a detector support frame, and a detector support base. The detector surface is arranged inside the housing and is used to receive the light emitted from the secondary reflector. The detector surface is fixed to one end of the cooling connecting rod, and the other end of the cooling connecting rod passes through the housing and is installed on the detector cooler. The detector cooler is installed on the support base through the support frame, and the detector support base and the secondary reflector support base are connected by an Invar connecting rod.

8. The cryogenic vacuum infrared radiometer according to claim 1, characterized in that, The modulation component, optomechanical structure, and infrared detector are all housed inside the vacuum cold chamber, while the electronic components are located outside the vacuum cold chamber. The shutter baffle includes a radiating plate with an internal cavity, and a refrigerant inlet / outlet connected to the internal cavity is provided on the radiating plate. Cooling pipes are coiled around the outer shell, and a liquid nitrogen tank is located outside the vacuum cold chamber. The liquid nitrogen tank is connected to the refrigerant inlet / outlet of the shutter baffle and the refrigerant inlet / outlet of the optomechanical structure's cooling pipes.

9. A method for testing ultra-low temperature vacuum infrared radiometers based on the shutter modulation principle, characterized in that, Using any one of the cryogenic vacuum infrared radiometers described in claims 1 to 8, the testing method comprises the following steps. The shutter baffle is used as a standard blackbody to control its stability at the first temperature; The shutter is controlled to modulate at a first fixed frequency, and the corresponding voltage signal value is collected. Adjust the shutter baffle to stabilize at the nth temperature, where n≥2, and repeat the above process to complete the calibration; Align the cryogenic vacuum infrared radiometer with the device under test and align its optical axis with the optical axis of the device under test; The device under test has completed its power-on preheating and stabilized at a certain temperature; The shutter baffle is modulated at a second fixed frequency, and the temperature of the shutter baffle is monitored until it stabilizes. The voltage signal value of the device under test is collected, and the voltage signal value is converted into a radiation temperature value according to the calibration result to complete the test of the device under test.

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