High-precision and high-temporal-resolution terahertz band τ-radiation measurement device

Abstract

The present invention provides a high-precision and high-temporal-resolution terahertz band τ-radiation measurement device, comprising an antenna module, a calibration assembly, a local oscillator signal source module, a refrigeration module, a superconducting receiver module, a data acquisition module, and a system control module. Measurement of atmospheric opacity and calibration of atmospheric radiation temperature at any site orientation are realized by means of the antenna module and the calibration assembly. The superconducting receiver module uses a superconducting SIS mixer, achieving an order-of-magnitude improvement in detection sensitivity compared with room-temperature Schottky mixer receivers. On the basis of the characteristics of narrow-band frequency gating and fast real-time spectral data readout of a high-spectral-resolution real-time FFT spectrometer of the data acquisition module, high-precision and high-temporal-resolution atmospheric opacity measurement can be realized. Additionally, by utilizing the high-frequency-resolution spectral processing capability of the real-time FFT spectrometer of the data acquisition module of the device, the device can function as a high-sensitivity and high-spectral-resolution spectral line receiver, thereby realizing high-spectral-resolution terahertz astronomical molecular spectral line observation.

Description

A high-precision, high-time-resolution terahertz band tau radiation measurement device Technical Field

[0001] This invention belongs to the field of terahertz radiometer technology and relates to a high-precision, high-time-resolution terahertz band tau radiation measurement device based on superconducting SIS. Background Technology

[0002] The terahertz (THz) band is generally defined as the range of 0.1–10 THz, covering the short millimeter wave to submillimeter wave (far-infrared) band. This band is the last electromagnetic band awaiting full development and research, an important supplement to the optical near-infrared and microwave bands, and a completely new band with significant scientific importance and broad application prospects. Because the terahertz band contains nearly half of the photon energy in the universe after the cosmic microwave background radiation and possesses abundant molecular spectral lines, it is considered particularly suitable for conducting the most important frontier scientific research in modern astronomy.

[0003] Due to the strong interaction between terahertz waves and atmospheric molecules, they are strongly absorbed by the atmosphere during their propagation. This significantly limits the observation efficiency of ground-based terahertz astronomical observation equipment, as the conditions of the ground-based astronomical sites are crucial. Currently, the best-equipped terahertz astronomical observatories worldwide are located in a very limited number of high-altitude, low-temperature, and arid regions, such as Antarctica, the Atacama Desert in Chile, Mauna Kea in Hawaii, and Greenland. Finding suitable sites for terahertz astronomical observatories has always been a key concern for astronomers.

[0004] Atmospheric opacity τ is one of the most direct and important parameters characterizing the features of a terahertz astronomical observatory site. Atmospheric opacity exhibits frequency dependence, displaying a window-like characteristic as it changes with frequency. That is, it exhibits low atmospheric opacity in certain frequency bands, while in other bands, due to strong atmospheric absorption, it displays high values ​​or consistently maintains extremely high atmospheric opacity. Furthermore, as frequency increases, the opacity of the atmospheric window in a specific frequency band tends to increase. Atmospheric conditions with higher opacity are less suitable for terahertz astronomical observations. In other applications of terahertz astronomical target imaging observations or terahertz interferometric observations, it is necessary to correct for the impact of atmospheric disturbances on the image quality of the imaging area, or to correct for the atmospheric effect on the interferometer's line-of-sight phase delay. Therefore, it is necessary to measure the rapid fluctuations in the atmospheric opacity of the observatory site.

[0005] Terahertz atmospheric opacity measurements are conducted within specific atmospheric frequency windows, primarily including 0.23 THz, 0.35 THz, 0.46 THz, 0.49 GHz, 0.66 THz, 0.85 THz, and 1.3–1.4 THz. The primary equipment for terahertz atmospheric opacity measurement is the terahertz radiometer. To accurately understand the atmospheric characteristics of the frequency band (specific atmospheric window) for terahertz astronomical observations, it is generally necessary to deploy a terahertz radiometer in the corresponding frequency band to measure atmospheric opacity. This information characterizes whether a terahertz astronomical site is suitable for conducting terahertz astronomical observations in that frequency band, and assesses the rapid fluctuations in atmospheric opacity at the site.

[0006] Currently, traditional tau radiometers primarily use room-temperature Schottky mixers with low detection sensitivity as receivers (the system's equivalent noise temperature is on the order of several thousand K). During atmospheric opacity measurements, a large intermediate frequency (IF) bandwidth is required to obtain more atmospheric radiation signal energy. Simultaneously, a chopper wheel is used to chop the broadband IF total power for synchronous detection and long-term integration (integration of 10-20 seconds or more for each observation elevation position) to obtain a sufficient detection signal-to-noise ratio. Therefore, completing an elevation scan observation takes 10-20 minutes or more, resulting in a long measurement time. This makes it difficult to meet the requirements of applications such as terahertz interferometry observations, which require rapidly changing atmospheric opacity fluctuations. Furthermore, the need for a wider IF inevitably increases susceptibility to external environmental interference, leading to decreased system stability. Furthermore, as the observation frequency increases, atmospheric opacity in the terahertz high-frequency band increases, meaning that the differences in atmospheric radiation brightness temperature at different pitch angles become weaker. Simultaneously, the detection sensitivity of the room-temperature Schottky mixer decreases significantly with increasing frequency. Therefore, even increasing the synchronous detection time makes it difficult to achieve a sufficient signal-to-noise ratio, leading to significant systematic errors in the measurement data, resulting in inaccurate measurements, and even making atmospheric opacity measurements impossible. Consequently, tau radiometers based on room-temperature Schottky mixers primarily focus on low-frequency bands with low atmospheric opacity (most commonly the 0.23 THz band) for atmospheric opacity measurements, and struggle to conduct high-precision and high-time-resolution measurements at higher frequency bands such as 0.46 THz and above. Summary of the Invention

[0007] To overcome the technical problems of existing terahertz tau radiometer devices in achieving high precision and high time resolution measurements in higher terahertz frequency bands, this invention provides a high-precision, high-time-resolution terahertz band tau radiation measurement device based on superconducting SIS.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention provides a high-precision, high-time-resolution terahertz band tau radiation measurement device, comprising an antenna module, a local oscillator signal source module, a cooling module, a superconducting receiver module, a data acquisition module, and a system control module. The antenna module includes an antenna and a reflector assembly. The antenna is capable of atmospheric elevation scanning at any azimuth. The received signal is transmitted through the signal transmission path of the reflector assembly to the receiving end of the superconducting receiver module. The cooling module includes a vacuum Dewar, a cold head, and a refrigerator, with the refrigerator providing cooling to the vacuum Dewar. The superconducting receiver module includes a superconducting mixer, a low-temperature low-noise amplifier, a room-temperature amplifier, and a low-pass filter connected in sequence. The superconducting mixer and the low-temperature low-noise amplifier are housed within the vacuum Dewar. The input signal from the antenna module enters through the Dewar window and passes through the heat sink formed by the cold head, enabling the superconducting mixer and the cryogenic low-noise amplifier to operate in the 8K temperature range. The room-temperature amplifier and low-pass filter are located outside the vacuum Dewar. The input signal from the antenna module and the local oscillator signal output from the local oscillator signal source module are mixed in the superconducting mixer, then the signal-to-noise ratio is improved by the cryogenic low-noise amplifier, the output signal is amplified by the room-temperature amplifier, and then filtered by the low-pass filter. The data acquisition module is used to perform spectrum processing on the intermediate frequency signal from the superconducting receiver module. The system control module is connected to the antenna module, the local oscillator signal source module, the cooling module, the superconducting receiver module, and the data acquisition module respectively, and is used to control the operation of the system.

[0010] Furthermore, the reflecting component includes a first reflector, a second reflector, and a third reflector; the first and second reflectors are parallel to each other, tilted at an angle of 45°, and distributed on the same horizontal plane; the third reflector is distributed below the second reflector and is mirror-symmetrical to the second reflector; the signal received by the antenna is reflected by the first reflector into the second reflector, reflected by the second reflector into the third reflector, and finally reflected by the third reflector into the superconducting receiver module, where it is received by the superconducting mixer.

[0011] Furthermore, the first reflector and the antenna are fixed together on the mounting surface of the pitch drive motor, and can rotate together under the drive of the pitch drive motor, with a pitch rotation angle of 0 to 90°; the second reflector, the first reflector, the antenna and the pitch drive motor are fixed together on the mounting surface of the azimuth drive motor, and can rotate together under the drive of the azimuth drive motor, with a horizontal rotation angle of -270 to +270°.

[0012] Furthermore, the antenna module is also equipped with a calibration component; the calibration component includes a room-temperature calibration blackbody, which is an aluminum square pyramid array obtained by molding, and its radiating surface is coated with a high thermal conductivity silicon carbide powder layer through low-temperature Stycast adhesive; the room-temperature calibration blackbody is located at the optical path beam waist plane in front of the superconducting receiver module, and the room-temperature calibration blackbody is fixed on the drive motor, and can rotate 180° under the drive of the drive motor to switch the signal path on / off; the drive motor is connected to the system control module.

[0013] Furthermore, the local oscillator signal source module includes a microwave signal source and a frequency multiplier chain. The frequency multiplier chain includes at least one set of frequency multiplier amplifiers connected in sequence. The microwave signal source is used to output the local oscillator signal. The frequency and power of the microwave signal source are tunable. The frequency multiplier chain is used to amplify the local oscillator signal by frequency multiplication. The microwave signal source is insulated, and the final stage frequency multiplier chain is located inside a vacuum Dewar.

[0014] Furthermore, the superconducting mixer is a superconducting SIS mixer made entirely of NbN material that can operate in the 8K temperature range, with an operating frequency band of 0.5THz.

[0015] Furthermore, the refrigerator is a low-power (500-watt-level) high-frequency pulse tube closed-loop refrigerator, providing the cooling power required for the stable operating ambient temperature of the all-NbN material superconducting SIS mixer in the 8K temperature range.

[0016] Furthermore, the ambient temperature amplifier has an intermediate frequency gain of over 30dB, and the low-pass filter has an effective bandwidth of 0–2.4GHz; the ambient temperature amplifier and the low-pass filter operate in a wide temperature range of -40°C.

[0017] Furthermore, the antenna is a card-type antenna, comprising a carbon fiber plate and a CNC aluminum antenna supported on the carbon fiber plate.

[0018] Furthermore, in the refrigeration module, the refrigeration unit and the cold head are connected by a vibration-damping sealed corrugated pipe to reduce the vibration of the cold head.

[0019] Furthermore, the data acquisition module employs a real-time FFT spectrum analyzer for real-time FFT spectrum processing of broadband intermediate frequency signals; the system control module includes an embedded computer and system control software running on the embedded computer. The embedded computer operates in a wide temperature range of -40 to 50°C. The system control software is used for parameter setting and control of the overall system, including controlling antenna elevation and azimuth scanning in the antenna module, switching the optical path of the calibration blackbody, tuning the local oscillator signal source module, biasing the superconducting mixer, biasing the low-temperature low-noise amplifier, starting and stopping the vacuum Dewar cooling, and starting and stopping the real-time FFT spectrum analyzer.

[0020] The beneficial effects of this invention are:

[0021] (1) This invention uses a small card antenna that can perform 0-90° pitch scanning and omnidirectional scanning, combined with an ultra-high sensitivity superconducting SIS mixer receiver (the overall equivalent noise temperature of the device is better than 300K in the 0.5THz band). Compared with the traditional Schottky mixer, the detection sensitivity can be improved by an order of magnitude. At the same time, combined with the real-time FFT spectrum analyzer, it has fast (10 milliseconds level) data readout capability and narrower bandwidth frequency gating characteristics (the spectrum analyzer channel spectrum bandwidth is better than 100kHz). Compared with the traditional total power readout method, it has higher flexibility and stronger anti-interference capability (easy to remove large interference signal spectrum in the band). Therefore, it can achieve high-precision and high-time resolution (minute level) measurement of atmospheric opacity in the 0.5THz band.

[0022] (2) The present invention integrates the antenna scanning and calibration components and separates them from other components of the device (including receiver components, local oscillator signal source components and system control components, etc.), thereby reducing the operating load of the antenna scanning and calibration components, avoiding the mechanical operation of non-operating parts, and improving the stability of the overall mechanical and electrical characteristics of the device.

[0023] (3) The real-time FFT spectrum analyzer used in this invention has high-frequency resolution spectrum processing capabilities, and can be used as a high-sensitivity, high-spectral-resolution spectral line receiver to achieve high sensitivity and high spectral resolution (R~10). 6 ) Terahertz molecular spectral line observations. Attached image description:

[0024] Figure 1 is a diagram of the high-precision, high-time-resolution terahertz band tau radiation measurement device of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] As shown in Figure 1, a high-precision, high-time-resolution terahertz band tau radiation measurement device includes an antenna module, a local oscillator signal source module, a cooling module, a superconducting receiver module, a data acquisition module, and a system control module.

[0027] The antenna module includes an antenna and a reflector. The antenna can perform atmospheric elevation scanning in any azimuth. The received signal is transmitted through the signal transmission path of the reflector to the receiving end of the superconducting receiver module. The cooling module includes a vacuum Dewar, a cold head, and a refrigerator. The refrigerator provides cooling to the vacuum Dewar. The superconducting receiver module enables high-sensitivity reception and mixing of atmospheric signals. It includes a superconducting mixer, a cryogenic low-noise amplifier, a room-temperature amplifier, and a low-pass filter connected in sequence. The superconducting mixer and cryogenic low-noise amplifier are located inside the vacuum Dewar. The input signal from the antenna module enters through the Dewar window and passes through the heat sink formed by the cold head, allowing the superconducting mixer and cryogenic low-noise amplifier to operate in the 8K temperature range. The room-temperature amplifier and low-pass filter are located outside the vacuum Dewar. The input signal from the antenna module and the local oscillator signal output from the local oscillator signal source module are mixed in the superconducting mixer, then the signal-to-noise ratio is improved by the cryogenic low-noise amplifier, the output signal is amplified by the room-temperature amplifier, and finally filtered by the low-pass filter. The data acquisition module performs spectral processing on the intermediate frequency signal from the superconducting receiver module. The system control module is connected to the antenna module, local oscillator signal source module, cooling module, superconducting receiver module, and data acquisition module, respectively, and is used to control the operation of the system.

[0028] The antenna is a 30cm card-type antenna, consisting of a carbon fiber plate and a CNC aluminum antenna supported on the carbon fiber plate.

[0029] As shown in Figure 1, the reflective assembly includes a first reflector (M1), a second reflector (M2), and a third reflector (M3). All three reflectors are metal, and their use enables the refraction and beam adjustment of the received signal transmission path to match the beam of the superconducting SIS mixer antenna in the receiver assembly. The first and second reflectors are parallel to each other, tilted at a 45° angle, and distributed on the same horizontal plane. The third reflector is located below the second reflector and is mirror-symmetrical to it. The signal received by the antenna is reflected by the first reflector into the second reflector, then by the second reflector into the third reflector, and finally by the third reflector into the superconducting receiver module, where it is received by the superconducting mixer.

[0030] Considering the ease of azimuth rotation and elevation scanning of the antenna, the first reflector and the antenna are fixed together on the mounting surface of the elevation drive motor. Driven by the elevation drive motor, they can rotate together to achieve antenna elevation scanning while maintaining the signal beam transmission characteristics between the first and second reflectors. The elevation rotation angle can be set from 0 to 90°. The second reflector, the first reflector, the antenna, and the elevation drive motor are fixed together on the mounting surface of the azimuth drive motor, allowing them to rotate together horizontally under the drive of the azimuth drive motor. By rotating the azimuth drive motor, the azimuth of the second reflector, the first reflector, and the antenna changes in a consistent manner, while ensuring that the signal beam transmission characteristics refracted vertically downwards by the second reflector remain unchanged, thus achieving azimuth scanning. The horizontal rotation angle can be set from -270° to +270°.

[0031] As shown in Figure 1, the antenna module also includes a calibration component, which is a room-temperature calibration blackbody. This component is used for calibrating the observed signal source, helping to understand errors caused by measurement stability issues, and also for calibrating the system sensitivity during system performance testing. The room-temperature calibration blackbody is an aluminum square pyramid array obtained through molding, with a high thermal conductivity silicon carbide powder layer attached to its radiating surface using low-temperature Stycast adhesive. The room-temperature calibration blackbody is positioned at the optical path beam waist plane in front of the superconducting receiver module and is equipped with a high-precision temperature sensor. The blackbody is fixed to a drive motor and can rotate 180° under the drive of the motor to switch the signal path on / off. The drive motor is connected to the system control module.

[0032] In this invention, both the azimuth and elevation scans of the antenna are driven by harmonic-reduced elevation and azimuth drive motors, respectively. The room-temperature calibration blackbody is switched via drive motors, effectively separating the movement of the antenna scanning and calibration components from the static state of the subsequent superconducting receiver components. This minimizes moving parts, saves system energy, and helps improve the stability of the system.

[0033] The local oscillator (LO) signal source module employs a solid-state LO signal source design combining a microwave reference source and frequency multiplier amplification, facilitating system integration. The LO signal source module includes a microwave signal source and a frequency multiplier chain. The frequency multiplier chain comprises at least one set of frequency multiplier amplifiers connected in sequence. The microwave signal source outputs the LO signal; its frequency and power are tunable. The frequency multiplier chain amplifies the LO signal by frequency multiplication. Since the LO signal source is a relatively temperature-sensitive component, insulation measures are implemented for the microwave signal source to improve its stability. Simultaneously, the final-stage frequency multiplier chain is placed inside a vacuum Dewar flask (to minimize temperature variations), preventing environmental temperature changes from affecting the stability of the LO signal source.

[0034] The superconducting mixer operates in the 0.5THz frequency band, covering atmospheric windows of 0.46THz and 0.492THz, enabling atmospheric opacity measurements in these bands. Considering low-temperature energy consumption, a superconducting SIS mixer made entirely of NbN (niobium nitride) material, capable of operating at 8K, is employed. Compared to the 4K temperature range, the 8K operation of the all-NbN superconducting SIS mixer significantly reduces the demand for Dewar cooling and the requirements for the Dewar refrigerator, thereby greatly reducing the overall system energy consumption.

[0035] The low-temperature, low-noise amplifier employs discrete components and achieves high gain through multi-stage cascading. It fully utilizes the low mixing loss characteristics of the superconducting SIS mixer, improving system sensitivity while reducing the noise figure requirements for the room-temperature intermediate frequency (IF). The room-temperature amplifier and low-pass filter operate over a wide temperature range of -40°C. The IF gain of the room-temperature amplifier is above 30 dB, and the effective bandwidth of the low-pass filter is 0–2.4 GHz to match the input bandwidth and power requirements of the subsequent spectrum analyzer.

[0036] In the cooling module, the cold plate of the 8K vacuum Dewar, which provides a low-temperature operating environment for the superconducting SIS mixer, adopts a multi-stage support method to reduce the overall size (height) and also helps to make full use of the space of the vacuum Dewar. To reduce the impact of the cyclic vibration of the cooling cycle of the closed-loop refrigerator on the 8K Dewar cold head, the refrigerator and the cold head are connected by a vibration-damping sealed bellows to reduce the vibration of the cold head, thereby reducing the fluctuation of the cooling temperature and improving the operating stability of the superconducting SIS mixer.

[0037] The refrigerator employs a high-frequency pulse tube closed-loop refrigerator with an integrated vacuum pump, providing continuous cooling for the 8K Dewar. The 8K closed-loop refrigerator offers the advantage of long-term cooling, making it suitable for applications requiring continuous observation over extended periods. Considering the system's operational requirements in the field, the high transition temperature of the superconducting SIS mixer, made entirely of NbN material, signifies a high operating temperature range, reducing the cooling power requirements of the high-frequency pulse tube closed-loop refrigerator. The closed-loop refrigerator utilizes a low-power (500W) and single-phase power supply, significantly reducing the power requirements and complexity of the field energy supply platform, improving system miniaturization and integration, and enhancing the ease of transportation and installation.

[0038] The data acquisition module employs a real-time FFT (Fast Fourier Transform) spectrum analyzer for real-time FFT spectrum processing of broadband intermediate frequency (IF) signals. The IF signal spectrum data acquisition is used for system performance testing and atmospheric opacity measurement. The real-time FFT spectrum analyzer provides a fast (10-millisecond-level) data readout method compared to traditional total power readout. Its fast (10-millisecond-level) data readout capability and narrower bandwidth frequency gating characteristics (spectrum analyzer channel bandwidth is better than 100kHz) offer greater flexibility and stronger anti-interference capabilities (facilitating the removal of large in-band interference signals). Combined with a superconducting SIS mixer signal receiver with ultra-high detection sensitivity, this enables higher precision and higher time resolution atmospheric opacity measurements.

[0039] The system control module includes an embedded computer and system control software running on the embedded computer. The embedded computer operates in a wide temperature range of -40 to 50°C. The system control software is used to set and control the parameters of the entire system, including controlling the antenna elevation and azimuth scanning in the antenna module, switching the optical path of the calibration blackbody, tuning the local oscillator signal source module, biasing the superconducting SIS mixer, biasing the low-temperature low-noise amplifier, starting and stopping the 8K vacuum Dewar cooling, and starting and stopping the real-time FFT spectrum analyzer.

[0040] In addition to setting parameters and controlling the start and stop of each component, the application software also monitors key status information of each component. Furthermore, since antenna azimuth setting and elevation scanning are required during atmospheric opacity measurement, the application software accurately records the azimuth angle, the elevation angle at different times, and the corresponding observation data at different elevation angles, and stores the data for subsequent measurement data preprocessing. The embedded computer has a reserved remote control interface, and the application software also has functions for external remote control and data interaction to meet the needs of unattended operation of the equipment under suitable field conditions.

[0041] The terahertz band tau radiation measurement device of this invention has an overall structural layout of three layers. From top to bottom, the top layer consists of the antenna module and calibration components; the second layer contains the cooling module (8K cooler and 8K Dewar), the local oscillator signal source module, the superconducting mixer, and the low-temperature low-noise amplifier; the third layer contains the vacuum pump (for vacuuming the Dewar), the room-temperature amplifier, the low-pass filter, the data acquisition module, the system control module, and the DC bias power supplies for each component of the system. The second and third layers are encapsulated with thermal insulation material.

[0042] In the second and third layer structures, the thermal control employs a unidirectional airflow design, utilizing adjustable-speed fans to ensure that the refrigerator located at the air inlet operates under relatively low temperatures, while the fan operates in a higher-temperature environment. A preheating unit is also designed for preheating before device startup and for temperature compensation during normal operation. The structural layout and thermal control are designed to fully utilize the waste heat of the refrigerator to maintain the operating temperature range of electronic components within the internal temperature system, preventing damage to these components under extremely low temperatures. The thermal control layout of this invention is rationally designed, ensuring that the heat-generating refrigerator operates under relatively low temperatures and fully utilizing its waste heat to provide temperature compensation for electronic components under extreme low-temperature conditions.

[0043] The terahertz band tau radiation measurement device of the present invention has two interfaces in its structural frame, including a 220V AC mains input interface for external AC mains power access and a gigabit network RJ45 interface for high-speed remote operation of embedded computer with external devices.

[0044] Example 1: Measurement of Atmospheric Opacity in the Zenith Direction

[0045] Step 1: Place the terahertz band tau radiation measurement device horizontally in the test field and connect it to a 220V power supply and a gigabit network cable. Start the external power supply. After the system control module is powered on, it will automatically start and enter the system control software interface, awaiting further manual operation. Simultaneously, the bias power supplies of the superconducting receiver assembly's superconducting SIS mixer, low-temperature low-noise amplifier, room-temperature amplifier, low-pass filter, real-time FFT spectrum analyzer, and local oscillator signal source assembly will be powered on. The portable computer outside the device will remotely switch to the embedded computer's system control software user interface via desktop access.

[0046] Step 2: Start the vacuum pump of the refrigerator assembly through the user interface of the system control software running on the embedded computer, and evacuate to an 8K Dewar. When the vacuum level reaches the target value (10... -4 (mBar level), start the chiller and begin cooling.

[0047] Step 3: Once the 8K Dewar cold plate reaches the target temperature range (8K temperature range), set the operating point of the superconducting SIS mixer, adjust the output power of the room temperature amplifier, set the observation frequency (e.g., 0.46THz) and power of the local oscillator signal source component, and set the integration time of the real-time FFT spectrum analyzer (on the order of 10ms).

[0048] Step 4: Start the azimuth drive motor of the antenna module, rotate the antenna to the observation position, and start the atmospheric opacity observation program on the user interface of the embedded computer's system control software.

[0049] Step 5: The atmospheric opacity observation program performs atmospheric pitch scanning (Sky-tipping) at preset pitch angles (15 preset pitch angles between 10° and 85°). The observation values ​​at each pitch angle are read point by point from the real-time FFT spectrum analyzer to form a set of atmospheric opacity Sky-tipping. The observation program of the system control module preprocesses the observation data to obtain the atmospheric opacity τ in the zenith direction of an observation (a set of observation processes is on the order of minutes).

[0050] Step 6: Repeat step 5 until the atmospheric opacity observation procedure is stopped. This will give you a series of atmospheric opacities τ in the zenith direction for that observation period.

[0051] Example 2: Observation of Astronomical Molecular Spectral Lines

[0052] This device can also be used for astronomical molecular spectral line observation, specifically through the following steps:

[0053] Step 1: Place the device horizontally in the test field, adjust the device to be level, and adjust the orientation of the antenna module and calibration components to ensure that the zero point of the device points due north.

[0054] Step 2: Connect the radiometer device to a 220V power supply and a gigabit network cable, and turn on the external power supply. After the system control module powers on, it will automatically start and enter the system control software interface, awaiting further manual operation. Simultaneously, the bias power supplies for the superconducting receiver assembly's superconducting SIS mixer, cryogenic low-noise amplifier, ambient temperature amplifier, low-pass filter, real-time FFT spectrum analyzer, and local oscillator signal source assembly will also be powered on. The external portable computer will remotely switch to the embedded computer's system control software user interface via desktop access.

[0055] Step 3: Start the vacuum pump of the refrigerator assembly through the user interface of the system control software running on the embedded computer, and evacuate the 8K Dewar. When the vacuum level reaches the target value (10... -4 (mBar level), start the chiller and begin cooling.

[0056] Step 4: Once the 8K Dewar cold plate reaches the target temperature range (8K temperature range), set the operating point of the superconducting SIS mixer, adjust the output power of the room temperature amplifier, set the observation frequency of the astronomical molecular spectrum of the local oscillator signal source component (e.g., 0.461THz), and set the basic integration time (1s) of the real-time FFT spectrum analyzer.

[0057] Step 5: Start the astronomical molecular spectral line observation program on the user interface of the system control software of the embedded computer, and input the coordinates (right ascension and declination) of the observation antenna.

[0058] Step Six: The astronomical molecular spectral line observation program will activate the azimuth drive motor and elevation drive motor of the antenna module to track the observed astronomical target. At the same time, it will perform a set of calibration processes and data integration using position modulation mode, including observation of the celestial signal source, cold space background, and blackbody calibration body.

[0059] Step 7: Repeat step 6 until the astronomical molecular spectral line observation program is stopped. This will obtain a series of astronomical molecular spectral line observation spectrum data for that observation period. Subsequently, amplitude calibration will be performed on each set of observation data (including the three sets of observation data: celestial signal source, cold space background, and blackbody calibration body) to obtain a series of astronomical molecular spectral line intensity information.

[0060] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A high-precision, high-time-resolution terahertz band tau radiation measurement device, characterized in that, It includes an antenna module, a local oscillator signal source module, a cooling module, a superconducting receiver module, a data acquisition module, and a system control module; The antenna module includes an antenna and a reflector. The antenna is capable of atmospheric elevation scanning in any orientation. The received signal is transmitted to the receiving end of the superconducting receiver module through the signal transmission path of the reflector. The refrigeration module includes a vacuum Dewar, a cold head, and a refrigeration unit, with the refrigeration unit providing cooling capacity to the vacuum Dewar. The superconducting receiver module includes a superconducting mixer, a cryogenic low-noise amplifier, a room-temperature amplifier, and a low-pass filter connected in sequence. The superconducting mixer and the cryogenic low-noise amplifier are housed inside a vacuum Dewar. The input signal from the antenna module enters through the Dewar window and passes through a heat sink formed by a cold head, enabling the superconducting mixer and the cryogenic low-noise amplifier to operate in the 8K temperature range. The room-temperature amplifier and the low-pass filter are located outside the vacuum Dewar. The input signal from the antenna module and the local oscillator signal output from the local oscillator signal source module are mixed in the superconducting mixer, then the signal-to-noise ratio is improved by the cryogenic low-noise amplifier, the output signal is amplified by the room-temperature amplifier, and finally filtered by the low-pass filter. The data acquisition module is used to perform spectrum processing on the intermediate frequency signal from the superconducting receiver module; The system control module is connected to the antenna module, local oscillator signal source module, cooling module, superconducting receiver module, and data acquisition module, respectively, and is used to control the operation of the system.

2. The high-precision, high-time-resolution terahertz band tau radiation measuring device according to claim 1, characterized in that, The reflective assembly includes a first reflector, a second reflector, and a third reflector; The first and second reflectors are parallel to each other and distributed on the same horizontal plane; the third reflector is distributed below the second reflector and is mirror-symmetrical to the second reflector; the signal received by the antenna is reflected by the first reflector into the second reflector, reflected by the second reflector into the third reflector, and finally reflected by the third reflector into the superconducting receiver module, where it is received by the superconducting mixer.

3. The high-precision, high-time-resolution terahertz band tau radiation measuring device according to claim 2, characterized in that, The first reflector and the antenna are fixed together on the mounting surface of the pitch drive motor, and can rotate together under the drive of the pitch drive motor; The second reflector, the first reflector, the antenna, and the pitch drive motor are all fixed on the mounting surface of the azimuth drive motor, and can rotate horizontally together under the drive of the azimuth drive motor.

4. The high-precision, high-time-resolution terahertz band tau radiation measuring device according to claim 1, characterized in that, The antenna module is also equipped with a calibration component; The calibration component includes a room-temperature calibration blackbody, which is an aluminum square pyramid array obtained by molding, and its radiating surface is covered with a high thermal conductivity silicon carbide powder layer by low-temperature Stycast adhesive. The room-temperature calibration blackbody is positioned at the optical path beam waist plane in front of the superconducting receiver module, and is fixed on the drive motor. It can rotate 180° under the drive of the drive motor to switch the signal path on / off. The drive motor is connected to the system control module.

5. The high-precision, high-time-resolution terahertz band tau radiation measuring device according to claim 1, characterized in that, The local oscillator signal source module includes a microwave signal source and a frequency multiplier chain. The frequency multiplier chain includes at least one set of frequency multiplier amplifiers connected in sequence. The microwave signal source is used to output a local oscillator signal. The frequency and power of the microwave signal source are tunable. The frequency multiplier chain is used to amplify the local oscillator signal by frequency multiplication. The microwave signal source is insulated, and the final frequency multiplier chain is located inside the vacuum Dewar.

6. The high-precision, high-time-resolution terahertz band tau radiation measuring device according to claim 1, characterized in that, The superconducting mixer is a superconducting SIS mixer made entirely of NbN material that can operate in the 8K temperature range, with a working frequency band of 0.5THz.

7. The high-precision, high-time-resolution terahertz band tau radiation measuring device according to claim 1, characterized in that, The ambient temperature amplifier has an intermediate frequency gain of over 30dB, and the low-pass filter has an effective bandwidth of 0–2.4GHz. The ambient temperature amplifier and low-pass filter operate in a wide temperature range of -40°C.

8. [Amended according to Rule 26, 20.11.2025] The high-precision, high-time-resolution terahertz band tau radiation measuring device according to claim 1 is characterized in that, The antenna is a card-type antenna, comprising a carbon fiber plate and a CNC aluminum antenna supported on the carbon fiber plate.

9. The high-precision, high-time-resolution terahertz band tau radiation measuring device according to claim 1, characterized in that, In the refrigeration module, the refrigeration unit and the cold head are connected by a vibration-damping sealed corrugated pipe to reduce the vibration of the cold head; The refrigerator is a high-frequency pulse tube closed-loop refrigerator.

10. The high-precision, high-time-resolution terahertz band tau radiation measuring device according to claim 1, characterized in that, The data acquisition module employs a real-time FFT spectrum analyzer for real-time FFT spectrum processing of broadband intermediate frequency signals. The system control module includes an embedded computer and system control software running on the embedded computer. The embedded computer operates in a wide temperature range of -40 to 50°C. The system control software is used to set and control the parameters of the entire system, including controlling the antenna elevation and azimuth scanning in the antenna module, switching the optical path of the calibration blackbody, tuning the local oscillator signal source module, biasing the superconducting mixer, biasing the low-temperature low-noise amplifier, starting and stopping the vacuum Dewar cooling, and starting and stopping the real-time FFT spectrum analyzer.

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