Blackbody-thermopile cooperative thermistor multi-temperature-point zero-point matching calibration method

Abstract

The application discloses a blackbody-thermoelectric pile cooperative thermistor multi-temperature-point zero-point matching calibration method. The method utilizes the Seebeck effect of the thermoelectric pile, establishes the accurate corresponding relationship of the blackbody standard temperature-thermistor resistance value through zero-point matching, carries out dynamic temperature scanning on different calibration point temperatures of the cavity, and obtains the thermistor parameters of multiple temperature points. Finally, the accurate R-T curve is fitted through the least square method. The method innovatively calibrates the thermistor through the blackbody heat radiation mode. The method does not need to disassemble the instrument, does not damage the stability of the original system, can complete the rapid calibration of the instrument on site, effectively reduces the calibration cost, and guarantees the temperature calibration accuracy and the calibration effect.

Description

Technical Field

[0001] This invention relates to the field of temperature sensor calibration technology, and in particular to a blackbody-thermopile coordinated thermistor multi-temperature point zero-point matching calibration method. Background Technology

[0002] Temperature is a physical quantity that indicates the degree of hotness or coldness of an object. Accurate temperature measurement is widely required in daily life, industrial production, and environmental monitoring. Traditional temperature measurement methods are mostly contact-based, but their application is limited in many complex scenarios, such as body temperature detection during pandemics, power line inspections, steel smelting, and surface temperature monitoring. Therefore, non-contact temperature measurement is receiving increasing attention. Among these methods, infrared thermometry based on thermopile technology provides an effective way to achieve non-contact, high-response temperature measurement by measuring the thermal radiation of an object.

[0003] Thermopile temperature measurement has many advantages: First, it is a non-contact measurement method, requiring no direct contact with the object being measured. This avoids interference with the temperature field of the target and is suitable for temperature measurement scenarios where contact is inappropriate, such as high temperature, high pressure, and corrosive environments. Second, it has a fast temperature response speed, quickly capturing dynamic temperature changes. It does not require slow waiting for the temperature to reach the target through heat conduction; instead, it obtains temperature through thermal radiation energy, with a response time down to the microsecond level, adapting to high-frequency temperature monitoring needs. Third, it has a wide measurement range, generally covering -80℃ to 150℃ or even wider. Due to these advantages, thermopile temperature measurement is widely used in non-contact human body temperature measurement, on-orbit thermal control of spacecraft, verification of surface temperature accuracy, and automated calibration of thermal infrared satellite remote sensors.

[0004] In thermopile infrared radiometers, thermistors are an indispensable core component. They are typically integrated into the thermopile substrate to measure the cold junction temperature, which ultimately directly contributes to the calculation of the true temperature of the object being measured. As an ambient temperature sensor providing a reference for temperature measurement, the accuracy of the thermistor's measurement directly determines the precision of the thermopile's target temperature measurement. However, due to material limitations, the thermistor's resistance-temperature (RT) curve exhibits significant nonlinearity. During long-term operation, this parameter is prone to drift due to factors such as cyclical changes in ambient temperature, instrument vibration, and thermistor aging, leading to a continuous decline in measurement accuracy. Regular calibration is essential to ensure long-term stable temperature measurement performance.

[0005] However, existing traditional thermistor calibration methods mainly involve placing the thermistor in a constant-temperature water bath and calibrating it by changing the water temperature. This method has the following key drawbacks:

[0006] 1. It relies on standard platinum resistance thermometers, high-precision temperature measuring bridges, and constant-temperature water baths / dry well tanks, and requires professional personnel to operate in a specialized metrology laboratory. The cost of a single calibration is high, making it prohibitively expensive for the large-scale need for periodic calibration of thermistors built into thermopile components.

[0007] 2. Using heat conduction contact measurement, each calibration temperature point in the constant temperature bath requires a considerable amount of time for the thermistor to stabilize and match the bath temperature, making it unsuitable for the rapid calibration needs of field operations. Examples include outdoor temperature measurement at calibration sites, online maintenance of industrial equipment, and outdoor monitoring at weather stations.

[0008] 3. Temperature gradients can easily occur during calibration. To ensure accurate temperature measurement by the thermopile's built-in thermistor, the original thermopile-type infrared radiometer structure needs to be modified, and the thermopile must be removed and placed in a constant temperature bath. This step is cumbersome, and the disassembly process can disrupt the stability of the original instrument system, potentially leading to a decrease in overall instrument performance.

[0009] In summary, existing calibration schemes are severely out of step with the actual needs of thermopile infrared radiometers. Thermopile infrared radiometers urgently require a thermistor calibration method that balances high accuracy and low cost, is adaptable to a wide temperature range, and can be automated on-site to ensure stable temperature measurement performance of the thermopile during long-term continuous operation. Summary of the Invention

[0010] The purpose of this invention is to provide a method for rapidly calibrating a thermistor at multiple temperature points on-site, while simultaneously achieving both high precision and low cost. The core of this method is to obtain the thermistor resistance values ​​at zero-point voltages at multiple temperature points through the coordinated operation of a blackbody-thermopile system, ultimately completing the thermistor calibration.

[0011] The technical solution adopted in this invention is as follows:

[0012] A blackbody-thermopile coordinated thermistor multi-temperature point zero-point matching calibration method includes the following steps:

[0013] S1. Select a suitable portable blackbody to establish a transfer reference.

[0014] S2, align the thermopile with the blackbody surface so that the radiation energy from the blackbody surface can be transferred to the hot end absorption layer of the thermopile, creating a temperature difference with the cold end measured by the thermistor;

[0015] S3 controls the temperature of the cavity containing the thermopile to be consistent with the blackbody radiation temperature, so that the output voltage difference is approximately zero;

[0016] S4. By linear fitting and zero-point voltage matching, the thermistor parameters at the temperature point are obtained.

[0017] S5, set different blackbody temperature points, and repeat steps S2 to S4 to obtain multiple calibration data points;

[0018] S6. The least squares method is used to fit the calibration data to obtain the RT curve of the thermistor.

[0019] Preferably, the surface emissivity of the blackbody radiation source is greater than 0.95.

[0020] Preferably, the blackbody radiation source is equipped with a software control system with a temperature control uncertainty of less than 30 mK.

[0021] Preferably, the temperature setting range of the blackbody radiation source is 0~100℃.

[0022] Preferably, the thermopile is a thermoelectric conversion device that converts temperature difference into voltage. It consists of multiple thermocouples connected in series to form hot and cold ends. The hot end is an absorption layer that absorbs the thermal radiation energy of the object being measured and forms a temperature difference with the cold end.

[0023] Preferably, the thermistor is located inside the thermopile. By controlling the heating rate of the cavity, the temperature inside the cavity is slowly raised from below the blackbody temperature to the blackbody temperature and then above the blackbody temperature. The voltage signal gradually increases from a negative value to a positive value. Simultaneously, the thermistor signal inside the cavity is also observed to rise. The measured value is taken within a short period of time. At this time, the voltage signal and the thermistor measurement signal have a linear relationship.

[0024] Preferably, zero-point voltage matching specifically involves: filtering thermal signal voltage data and corresponding thermistor voltage data for several minutes before and after the thermal signal reaches 0V at each calibration point; using the thermal signal voltage data as the abscissa and the corresponding thermistor voltage data as the ordinate; and performing linear fitting between the two to obtain the following relationship:

[0025] ;

[0026] In the formula, This is the voltage signal of the thermistor at the cold end of the thermopile. The thermal signal voltage is generated by the voltage difference between the hot and cold ends of the thermopile, where k and b are the slope and intercept of the linear fitting, respectively.

[0027] Then, setting the thermal signal voltage to 0, calculate the corresponding voltage signal of the thermistor:

[0028] .

[0029] Preferably, after obtaining the thermistor voltage value at each calibration point, the resistance value of each thermistor is further calculated using the voltage divider law:

[0030] ;

[0031] In the formula, These are series voltage divider resistors. For external voltage, This is the voltage signal across the thermistor. To ultimately obtain the thermistor value.

[0032] Preferably, by using the thermistor value obtained at each calibration point, the RT characteristic curve of the thermistor is obtained by fitting the Steinhart-Hart equation:

[0033] ;

[0034] In the formula, T is the temperature of the calibration point, R is the corresponding thermistor value, and A, B, and C are equation coefficients; let , , The three optimal coefficients A, B, and C were obtained by fitting using the least squares method.

[0035] Preferably, the time before and after 0V is 3 minutes.

[0036] The present invention has the following beneficial effects:

[0037] 1. Innovative Calibration Logic. Previously, blackbodies were only used to evaluate the overall radiation thermometry performance of thermopile, while the thermostatic bath was used for thermistor calibration; their uses were unrelated. This invention, through Seebeck effect zero-point voltage matching, allows blackbodies to be directly used for calibrating thermistors built into the thermopile.

[0038] 2. The physical nature of the calibration method has changed. Traditional calibration methods rely on heat conduction, while this method primarily uses heat radiation. Therefore, it features a rapid temperature response.

[0039] 3. High calibration accuracy and excellent calibration effect. This method traces back to the blackbody, ensuring accurate temperature calibration. Furthermore, compared to contact measurements, where the external temperature needs to be conducted to the thermistor, potentially introducing a temperature gradient, this method utilizes thermal radiation. The blackbody temperature is the same as the cold junction temperature of the thermopile, and the thermistor is built into the thermopile, directly measuring the cold junction temperature, resulting in a smaller temperature gradient.

[0040] 4. Effectively reduces calibration costs. This method eliminates the need for standard platinum resistance thermometers, high-precision temperature bridges, and constant-temperature water / dry well tanks. The operation can be completed using a blackbody and a gentle heating device, making it ideal for regularly calibrating the thermistors built into the instrument's thermopile.

[0041] 5. Simple to operate, no need to disassemble the instrument, and quick calibration of the instrument can be completed on site without compromising system stability. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of an example device of the present invention;

[0043] Figure 2 This is a flowchart of the method of the present invention;

[0044] Figure 3 This invention relates to a thermopile thermistor voltage divider measurement circuit. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above objectives, this invention adopts the following technical solution.

[0046] like Figure 1 The image shows a suitable supporting device for a blackbody-thermopile coordinated thermistor multi-temperature point zero-point matching calibration method, including a corresponding blackbody radiation module, a programmable heating module, and a thermopile detection module.

[0047] The blackbody radiation module mainly consists of a portable surface-source blackbody and blackbody radiation control software. The software can control the temperature of the surface-source blackbody radiation surface with an accuracy of 0.03K and a software setting resolution of 0.001K. The temperature can be set from 0 to 100℃, effectively providing a temperature calibration reference at room temperature.

[0048] The programmable heating module mainly consists of a metal shell, insulation cotton, heating resistance wire, and feedback thermistor, used to control the cavity temperature. The metal shell, placed in the inner layer and in direct contact with the thermopile, serves two purposes: first, the metal's high thermal conductivity ensures a uniform internal temperature field; second, the metal shell creates a Faraday cage effect, effectively shielding external electromagnetic interference signals and reducing the impact of weak signals output by the thermopile. The insulation cotton, placed in the outer layer and in direct contact with the metal shell, also serves two purposes: first, it prevents heat loss, allowing the cavity temperature to be raised to a relatively high level; second, it increases the specific heat capacity, meaning more energy needs to be absorbed to raise the temperature by the same amount, effectively slowing down the heating rate and facilitating stable temperature control of the cavity. The heating resistance wire, feedback thermistor, and PID temperature controller combine to form a closed-loop temperature control circuit. By applying different output voltages to the resistance wire, the heating power of the cavity is controlled, and the feedback thermistor determines whether the controlled temperature has been reached.

[0049] The thermopile detection module, consisting of a thermopile and a high-precision data acquisition unit, is used to measure the analog voltage output by the thermopile. The thermistor within the thermopile is the object requiring calibration; it measures the cold junction temperature, changing its resistance according to the temperature change, and then outputs a temperature-dependent voltage signal through voltage division. The thermal signal in the thermopile is the voltage signal generated by the Seebeck effect due to the temperature difference between the absorption layer and the cold junction. When the surface source blackbody temperature matches the cold junction temperature of the thermopile, the voltage signal output is 0V, thus forming a bridge between the surface source blackbody temperature and the cold junction temperature. The high-precision data acquisition unit accurately acquires both signals. It measures the voltage difference generated by the temperature difference between the hot and cold junctions of the thermopile using thermal signals V+ and V-, and measures the thermistor voltage divider voltage using thermistors R+ and R-. The measurement accuracy is at the μV level, meeting the measurement requirements for the weak output signal of the thermopile.

[0050] If the calibration is performed using the internal thermistor of a thermopile-type instrument, the thermopile detection module is not required. Simply replace the thermal radiation voltage signal and the thermistor-measured temperature with the original instrument output values.

[0051] This invention provides a blackbody-thermopile coordinated thermistor multi-temperature point zero-point matching calibration method, including reference establishment, thermal radiation energy transfer, cavity temperature isothermal control, zero-point voltage matching, multi-temperature point coverage, and RT data fitting.

[0052] Reference Establishment. A blackbody radiation source is used as the temperature reference, such as a portable surface-source blackbody used for calibration in various work sites. The surface-source emissivity needs to be greater than 0.95 to effectively reduce the influence of ambient reflected radiance; it is equipped with a software control system with a temperature control uncertainty of less than 30 mK to meet the requirements for calibrating a high-precision thermal radiation reference; the temperature setting range is 0~100℃, covering the ambient temperature requirements of most thermopile working sites.

[0053] Thermal radiation energy transfer. By setting a blackbody temperature value, the surface temperature of the blackbody can be kept constant. Then, thermal radiation transfers the temperature from the blackbody surface to the thermopile's absorption layer. A thermopile is a thermoelectric conversion device based on the Seebeck effect, which converts temperature difference into voltage. It consists of multiple thermocouples connected in series, forming hot and cold ends. The hot end is mainly the absorption layer, which has high emissivity and approximates a blackbody. When it absorbs the thermal radiation energy from the object being measured, it creates a temperature difference with the cold end. The absorption layer has a small specific heat capacity, allowing for a millisecond-level response to thermal radiation, rapidly completing the thermal radiation energy transfer from the blackbody to the thermopile.

[0054] Cavity temperature isostatic control. Due to the Seebeck effect, when there is a constant temperature difference between the hot and cold ends of the thermopile, it outputs a constant voltage signal. When the cold end temperature and the blackbody radiation temperature are the same, the thermal signal output voltage is zero, indicating that there is no temperature difference and the blackbody radiation temperature is equal to the cold end temperature. By controlling the cavity to be at the same temperature as the blackbody radiation temperature, the blackbody radiation temperature can be used as the temperature measured by the thermistor, thus establishing a correlation chain of "blackbody radiation temperature - thermopile cold end temperature - thermistor measured temperature".

[0055] Zero-point matching: Since thermistors are typically located inside the instrument's thermopile, directly controlling their temperature to precisely reach the blackbody radiation temperature is extremely difficult. However, this problem can be cleverly solved by leveraging the fast response speed of the thermopile (typically 20ms~100ms) and zero-point interpolation matching. By controlling the cavity heating rate (typically 0.1℃ / min, i.e., 1.7mK / s), the temperature inside the cavity is slowly raised from below the blackbody temperature to the blackbody temperature, and then above it. During this time, the thermopile output voltage signal gradually rises from a negative value to a positive value, and the thermistor signal inside the cavity is observed to rise accordingly. Taking measurements over a short period, such as within 10 seconds (a 17mK change in cold junction temperature), the voltage signal and the thermistor measurement signal can be considered to have a completely linear relationship. Through linear fitting, a linear equation can be obtained between the voltage signal and the thermistor measurement signal. Setting the voltage signal to zero, the thermistor measurement signal value corresponding to the blackbody radiation temperature can be calculated.

[0056] Multi-temperature coverage: The instrument's thermistor is set to operate within a specific temperature range. The heating device continuously heats the thermistor, ensuring the measured temperature passes through this range. Simultaneously, multiple calibration points are set for the blackbody within the operating temperature range. Whenever the cavity temperature passes through a calibration point and the voltage crosses zero, the blackbody sets the next calibration point, ultimately completing the calibration of multiple temperature points.

[0057] Least squares fitting: There are two cases. If it is a bare thermopile measurement, the resistance-temperature (RT) fitting curve is obtained by fitting with the Steinhart-Hart third-order equation. If it is an instrument signal measurement, the thermistor resistance value has been converted into a temperature value, and the original measured temperature-calibrated temperature (Tm-T) fitting curve is obtained by fitting with a linear equation.

[0058] In this invention, a blackbody is used as a reference source to transfer energy through thermal radiation, instead of using a standard platinum resistance thermometer as a reference to transfer temperature through a constant temperature water bath or water conduction.

[0059] In this invention, the temperature is raised and lowered slowly to ensure uniform temperature throughout the cavity. The background temperature measured by the thermistor is the cold end temperature of the thermopile. The metal cavity housing the thermopile is made of a metal with high thermal conductivity, a smooth inner wall, and no significant thermal resistance structure, thus creating a uniform internal temperature field. Simultaneously, the metal cage exhibits the Faraday cage effect, effectively shielding against external electromagnetic radiation interference and reducing its impact on the weak output signal of the thermopile. The cavity temperature control device consists of insulation cotton, a heating resistance wire, a feedback thermistor, and a PID temperature controller. The insulation cotton prevents heat loss and increases the overall specific heat capacity of the device, enhancing the control capability of the heating rate. The PID temperature controller, heating resistance wire, and feedback thermistor form a closed-loop temperature control circuit to achieve stable temperature rise and fall.

[0060] In existing technologies, it is very difficult to strictly control the cavity temperature and the blackbody radiation temperature to be the same. This method innovatively utilizes the fast response of thermopile. By heating the cavity temperature and passing through the blackbody temperature calibration point, and then selecting the collected data over a period of time, the corresponding value of the thermistor for the zero-point voltage at the matching temperature point is calculated through linear fitting.

[0061] Furthermore, by covering the thermistor values ​​at multiple temperature points, the fitting accuracy and dynamic range can be effectively improved.

[0062] Furthermore, based on the Steinhart-Hart equation and the linear equation, the least squares method is used to fit multiple sets of calibration data, outputting accurate RT characteristic curves and fitting coefficients.

[0063] Based on actual calibration requirements, an operation flowchart was drawn, as follows: Figure 2 As shown, the following specific operating steps are given:

[0064] Step 1: Instrument Installation. Install the thermopile inside the metal housing. Lead the signal cable (shielded cable) out through the metal slot and connect it to the high-precision data acquisition unit. Wrap the metal housing with an electric heating blanket and fix the entire unit vertically on the platform. Keep the platform parallel to the blackbody and adjust its height so that the thermopile's detection field of view completely fills the blackbody's surface source radiation.

[0065] Step 2: Device Preheating. The blackbody surface source temperature is controlled to the ambient temperature via computer software, and the cavity temperature is set to the ambient temperature via a PID high-precision controller. Observe the measured values ​​from the high-precision data acquisition device. Preheating is complete when the signal values ​​stabilize and the standard deviation is within 3μV.

[0066] Step 3: Set calibration points. The current version of the electric heating blanket does not have a cooling function, therefore the calibrable temperature range is room temperature to 100℃. For a wider dynamic calibration range, the device should be placed outdoors in winter or in an indoor freezer to provide a basic low temperature. When the ambient temperature is 20℃, the calibration range is 20~100℃, starting from 22℃, setting a calibration point every 2℃. In Step 2, since both the blackbody and cavity were set to an ambient temperature of 20℃, this may not match the actual temperature. Therefore, the 20℃ point is discarded. The blackbody temperature needs to be set slightly higher than the ambient temperature, such as 22℃, to ensure that subsequent cavity heating passes through the calibration point.

[0067] Step 4: Slowly heat the cavity. The heating rate of the cavity is controlled by a PID controller, increasing by 0.1℃ per minute. This allows the temperature inside the cavity to slowly rise from below the calibration point temperature to the calibration point temperature, and eventually exceed it.

[0068] Step 5: Set the next calibration point. After the cavity temperature passes the calibration point temperature, wait about 5 minutes and then set the blackbody temperature to the next calibration point.

[0069] Step 6: Repeat steps 4 and 5 until all calibration points are completed.

[0070] Step 7: Zero-point matching. Filter the thermal signal voltage data and the corresponding thermistor voltage data for 3 minutes before and after the thermal signal reaches 0V at each calibration point. Since the cavity temperature change is very small within these 3 minutes, the voltage data can be approximated as a linear change. Plotting the thermal signal voltage data on the x-axis and the corresponding thermistor voltage data on the y-axis, a linear fit is performed to obtain the following relationship:

[0071] ;

[0072] In the formula, This is the voltage signal of the thermistor at the cold end of the thermopile. The thermal signal voltage is generated by the voltage difference between the hot and cold ends of the thermopile, where k and b are the slope and intercept of the linear fitting, respectively.

[0073] By setting the thermal signal voltage to 0, the corresponding voltage signal of the thermistor can be calculated:

[0074] ;

[0075] Step 8: Calculation of thermistor values ​​at calibration points. Based on Step 7, the thermistor voltage value at each calibration point can be calculated. For example... Figure 3 As shown, the resistance value of each thermistor can be further calculated using the voltage divider law:

[0076] ;

[0077] In the formula, These are series voltage divider resistors. This is an external voltage, typically 2.5~3.3V. This is the voltage signal across the thermistor. To ultimately obtain the thermistor value.

[0078] Step Nine: Fitting the RT Characteristic Curve. Step Eight yielded the thermistor value at each calibration point. Then, using the Steinhart-Hart equation, the RT characteristic curve of the thermistor was fitted.

[0079] ;

[0080] In the formula, T is the temperature at the calibration point, and R is the corresponding thermistor value. A, B, and C are the coefficients of the Steinhart-Hart equation, which vary depending on the type of thermistor.

[0081] make , , The three optimal coefficients A, B, and C were obtained by fitting using the least squares method.

Claims

1. A method for zero-point matching calibration of a blackbody-thermopile coordinated thermistor at multiple temperature points, characterized in that, Includes the following steps: S1, a portable blackbody is selected as the temperature transfer reference; S2, align the thermopile with the blackbody surface so that the blackbody radiation energy is transferred to the hot end absorption layer of the thermopile, creating a temperature difference with the cold end measured by the thermistor; S3, adjust the temperature of the cavity where the thermopile is located to make it close to the blackbody radiation temperature, until the thermopile output voltage signal is close to zero; S4. By linear fitting and zero-point voltage matching, the thermistor parameters at the temperature point are obtained. S5, set different blackbody temperature points, and repeat steps S2 to S4 to obtain multiple calibration data points; S6. Perform least squares fitting on the calibration data to obtain the RT curve of the thermistor; Zero-point voltage matching specifically involves: filtering thermal signal voltage data and corresponding thermistor voltage data for several minutes before and after the thermal signal reaches 0V at each calibration point; using the thermal signal voltage data as the abscissa and the corresponding thermistor voltage data as the ordinate; and performing linear fitting between the two to obtain the relationship: ； In the formula, This is the voltage signal of the thermistor at the cold end of the thermopile. The thermal signal voltage is generated by the voltage difference between the hot and cold ends of the thermopile, where k and b are the slope and intercept of the linear fitting, respectively. Then, setting the thermal signal voltage to 0, calculate the corresponding voltage signal of the thermistor: ； After obtaining the thermistor voltage value at each calibration point, the resistance value of each thermistor is further calculated using the voltage divider law: ； In the formula, These are series voltage divider resistors. For external voltage, This is the voltage signal across the thermistor. To ultimately obtain the thermistor value; By obtaining the thermistor value at each calibration point, the RT characteristic curve of the thermistor is obtained by fitting the Steinhart-Hart equation: ； In the formula, T is the temperature of the calibration point, R is the corresponding thermistor value, and A, B, and C are equation coefficients; let , , The three optimal coefficients A, B, and C were obtained by fitting using the least squares method.

2. The blackbody-thermopile coordinated thermistor multi-temperature point zero-point matching calibration method according to claim 1, characterized in that, The surface emissivity of a blackbody radiation source is greater than 0.

95.

3. The blackbody-thermopile coordinated thermistor multi-temperature point zero-point matching calibration method according to claim 1, characterized in that, The blackbody radiation source is equipped with a software control system, and the temperature control uncertainty is less than 30 mK.

4. The blackbody-thermopile coordinated thermistor multi-temperature point zero-point matching calibration method according to claim 1, characterized in that, The temperature setting range for the blackbody radiation source is 0~100℃.

5. The blackbody-thermopile coordinated thermistor multi-temperature point zero-point matching calibration method according to claim 1, characterized in that, A thermopile is a thermoelectric conversion device that converts temperature difference into voltage. It consists of multiple thermocouples connected in series, forming hot and cold ends. The hot end is an absorption layer that absorbs the thermal radiation energy of the object being measured, creating a temperature difference with the cold end.

6. The blackbody-thermopile coordinated thermistor multi-temperature point zero-point matching calibration method according to claim 1, characterized in that, The thermistor is located inside the thermopile. By controlling the heating rate of the cavity, the temperature inside the cavity is slowly raised from below the blackbody temperature to above the blackbody temperature. During this process, the output voltage signal of the thermopile gradually changes from negative to positive, and the thermistor signal inside the cavity also rises accordingly. The voltage signal and the thermistor signal are acquired in real time, and the data segment near the zero-crossing point of the voltage signal is linearly processed.

7. The blackbody-thermopile coordinated thermistor multi-temperature point zero-point matching calibration method according to claim 1, characterized in that, The time before and after 0V is set to 3 minutes.

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