A double optical path cold mirror dew point meter measuring method

Abstract

The present application relates to a kind of based on double optical path cold mirror dew point meter measurement method, belong to dew point measurement field, solve the problem that due to the influence of environmental temperature, light source fluctuation and clutter and other factors in prior art leads to inaccurate dew point temperature measurement.Method comprising: precooling operation is carried out to the measuring cavity of dew point meter;Measured gas is blown into measuring cavity, the measuring cavity is cooled, reference light path voltage and main light path voltage are collected in real time and difference, and dew point temperature is obtained according to pressure difference;The dew point temperature is compensated and corrected using correction function to obtain corrected dew point temperature;Cavity temperature is raised, and the corrected dew point temperature of N times is measured repeatedly, and the average of the corrected dew point temperature of N times is taken as final dew point temperature.The present application can improve the speed and accuracy of dew point measurement using the test method.

Description

Technical Field

[0001] This invention relates to the field of dew point temperature measurement, and more particularly to a method for measuring dew point temperature using a dual-path cold mirror dew point meter. Background Technology

[0002] Gas humidity, representing the degree of dryness or wetness of a gas, is a physical quantity indicating the amount of water vapor it contains. At a given temperature, the less water vapor in a given volume of gas, the drier the gas; the more water vapor, the more humid. The degree of dryness or wetness of a gas is called "humidity." Gas humidity measurement is easily affected by many factors and is far less mature than the measurement of parameters such as temperature and pressure. Humidity measurement has always been one of the challenging problems in the world's metrology field. Many industrial production processes require the measurement of gas humidity, and humidity detection is a crucial link in controlling the quality level of gases or compressed air and improving gas source systems. Under isobaric conditions, water vapor in the gas is cooled until a condensed phase appears. By controlling the temperature of the dew layer using a dew layer sensor, the water vapor and water in the gas are brought into thermodynamic equilibrium. The accurate measurement of this dew layer temperature is the dew point temperature of the gas. Currently, there are many types of instruments for measuring moisture, and the main methods include gravimetric methods, electrolytic methods, resistance-capacitive methods, and dew point methods. Electrolysis requires high gas flow rates and has a long drying time; the resistance-capacitance method has poor accuracy, short lifespan, long testing time, and high gas consumption; the dew point method is a high-precision measurement method with good stability, low gas consumption, and long lifespan. In China, mirror dew point meters are mainly used as standard instruments for humidity measurement.

[0003] The main technical approaches to dew point meters include cold mirror dew point meters, electrical sensor dew point meters, dielectric dew point meters, crystal oscillator dew point meters, and infrared dew point meters. Dew point refers to the temperature at which water vapor condenses into dew as a given amount of air is gradually cooled under constant vapor pressure. More precisely, it is the thermodynamic dew point temperature, where the water vapor content in the air is exactly equal to the water vapor content at saturation. Dew point temperature is often used to represent the trace amount of water contained in a gas. The cold mirror method is based on this theory and features high accuracy and a wide measurement range. Cold mirror dew point meters measure based on the photoelectric principle. Most precision dew point meters use a photoelectric system to determine dew formation. The photoelectric detection system mainly includes a stable light source and a reflected light receiving system. Parallel light from the light source is reflected by the mirror, and the reflected light is received by a phototube or photosensitive element. Before condensation forms on the mirror surface, the incident and reflected light flux is essentially stable. When condensation appears, the reflected light is scattered, reducing the amount of light received by the light receiving system. Accurately determining whether dew has appeared can be achieved by tracking and analyzing changes in the received light intensity. However, due to factors such as ambient temperature and fluctuations in the light source, certain measurement errors can occur in determining whether condensation has actually formed on the mirror surface. Furthermore, during dew point measurement, many complex practical factors can cause numerous interference signals in the acquired photoelectric differential signal, which are detrimental to dew point identification. The presence of these clutter signals significantly affects the calculation of the curve direction index, leading to misjudgments of the dew point temperature. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a method for measuring dew point temperature based on a dual-optical-path cold mirror dew point meter, in order to solve the problem of inaccurate dew point temperature determination caused by environmental and equipment factors in existing methods.

[0005] The objective of this invention is mainly achieved through the following technical solutions:

[0006] This invention provides a method for measuring dew point using a dual-optical-path cooled mirror dew point meter, comprising the following steps:

[0007] Step S1: Pre-cool the measuring chamber of the dew point meter; wherein the measuring chamber of the dew point meter is divided into a reference chamber and a measuring chamber with the same ambient temperature.

[0008] Step S2: The gas to be measured is blown into the measuring cavity to cool the measuring cavity. The reference optical path voltage and the main optical path voltage are collected in real time and the difference is calculated. The dew point temperature is obtained based on the pressure difference.

[0009] Step S3: The dew point temperature is compensated and corrected using a correction function to obtain the corrected dew point temperature; wherein, the correction function is obtained by using a dew point adjustable gas generator to output gas with a known dew point temperature and measuring it, and then fitting it using the least squares method.

[0010] Step S4: Increase the cavity temperature and repeat the measurement N times. Calculate the average of the corrected dew point temperatures N times as the final dew point temperature; where N is an integer greater than or equal to 2.

[0011] Furthermore, the pre-cooling operation includes:

[0012] The temperature of the measuring cavity is collected in real time, and gas is blown into the measuring cavity.

[0013] When the temperature of the measuring cavity is greater than or equal to the set temperature threshold, the temperature of the measuring cavity is reduced to the lowest value of the dew point meter's measurement range, and then the temperature of the measuring cavity is increased until the main optical path voltage is equal to the reference optical path voltage.

[0014] When the measured temperature is lower than the set temperature threshold, the temperature of the measuring cavity is increased until the main optical path voltage is equal to the reference optical path voltage.

[0015] Furthermore, obtaining the dew point temperature includes:

[0016] Lower the temperature of the measuring cavity;

[0017] The reference optical path voltage and the main optical path voltage are continuously acquired, and the reference optical path voltage and the main optical path voltage are calculated using anti-pulse interference averaging filter.

[0018] The difference between the reference optical path voltage and the main optical path voltage is obtained;

[0019] When the difference equals the set dew point threshold, the temperature of the measuring cavity is the dew point temperature.

[0020] Furthermore, the continuous acquisition of multiple reference optical path voltages and main optical path voltages, using anti-pulse interference averaging filtering, includes:

[0021] The reference optical path voltage and the main optical path voltage are continuously collected several times, and the maximum and minimum values ​​are removed respectively, and the average value of the remainder is taken.

[0022] After multiple averaging processes, the maximum and minimum values ​​of the average values ​​of the reference optical path voltage and the main optical path voltage are removed, and then the average values ​​are taken again to obtain the final reference optical path voltage and main optical path voltage.

[0023] Furthermore, the correction function is obtained by using a gas generator with an adjustable dew point outputting a gas at a known dew point temperature, measuring the gas, and then fitting the data using the least squares method, including:

[0024] The measurement range is divided into multiple temperature zones;

[0025] Several temperature values ​​are randomly selected within each temperature range, and the corresponding dew point temperature gas is blown out using the dew point adjustable gas generator as the dew point standard value.

[0026] The dew point temperature of the gas blown out by the dew point adjustable gas generator is measured using the dew point meter as the dew point measurement value.

[0027] By subtracting the standard dew point value from the measured dew point value, several difference values ​​are obtained;

[0028] Using the measured dew point value as the independent variable and the difference between the standard dew point value and the measured dew point value as the dependent variable, a polynomial fitting is performed using the least squares method to obtain the least squares fitting function as the correction function.

[0029] Furthermore, the least squares fitting function is calculated through the following steps:

[0030] Step S11: Let the fitting polynomial be as follows:

[0031]

[0032] Where x is the independent variable; y is the dependent variable; k is a constant; a k For coefficients;

[0033] Step S12: Calculate the sum of the distances from each point to the curve, i.e., the sum of squared errors, as follows:

[0034]

[0035] Where i is the number of selected temperature values.

[0036] Step S13: According to the least squares principle, calculate a. i Partial derivatives:

[0037]

[0038]

[0039] Step S14: Simplify and transform into matrix form as follows:

[0040]

[0041] Step S15: Solve the linear equation to obtain the coefficients a. k Substituting the fitting polynomial from step S11, we obtain the final correction function.

[0042] Furthermore, the step of averaging the corrected dew point temperatures as the final dew point temperature includes: continuously measuring the dew point temperature of the gas being measured, and when the difference between at least three consecutive dew point temperatures is less than or equal to a set dew point accuracy threshold, averaging the dew point temperatures as the final dew point temperature.

[0043] Furthermore, the measuring cavity is divided into a reference cavity and a measuring cavity of the same size, separated by an opaque temperature balancing plate to keep the two cavities at the same temperature and to isolate light.

[0044] The light emitted by the LED of the dew point meter is focused by a convex lens to a beam splitter, which then splits the light into two beams of equal intensity.

[0045] The reference optical path is one of the beams passing through a reference cavity and being focused by a convex lens onto a silicon photovoltaic cell;

[0046] The main optical path consists of another beam of light that passes through a beam splitter, is reflected by the mirror of the measuring cavity, and then focused by a convex lens onto another silicon photovoltaic cell.

[0047] Furthermore, the reference optical path voltage is the voltage generated by the reference optical path beam after it is received by the reference optical path silicon photovoltaic cell receiving module and converted into a reference optical path voltage by the AD conversion module and then transmitted to the control board.

[0048] The main optical path voltage is the voltage generated when the main optical path beam is received by the main optical path silicon photovoltaic cell receiving module, converted into a main optical path voltage by the AD conversion module, and then transmitted to the control board.

[0049] Furthermore, the measuring cavity is connected to a refrigerator and a temperature sensor; the temperature of the measuring cavity is adjusted by the refrigerator; and the temperature of the measuring cavity is obtained by the temperature sensor.

[0050] One side of the temperature sensor is connected to the mirror surface in the measuring cavity, and the other side transmits data to the control board via a 232 serial port.

[0051] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0052] 1. This invention employs dual-optical-path technology, using a beam splitter to divide the light source into two identical light sources, which pass through a reference cavity and a measurement cavity with the same ambient temperature, respectively, ensuring that the optical path is basically consistent. This avoids the influence of light source fluctuations and ambient temperature changes on the measurement results, thereby improving the accuracy of dew point measurement.

[0053] 2. The present invention pre-cools the measuring cavity before measurement, which can shorten the measurement time and increase the measurement speed. In addition, the moisture in the air in the measuring cavity condenses into frost during the pre-cooling process and is carried out of the measuring cavity by the gas being measured during the pre-cooling and heating stage, thus avoiding the influence of the moisture in the air in the measuring cavity on the measurement results.

[0054] 3. This invention uses an adjustable dew point gas generator to perform mean filtering on the dew point temperature measured by the dew point meter and formulates a correction function to further reduce noise interference and improve the accuracy of the measurement results.

[0055] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0056] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0057] Figure 1 This is a schematic diagram of the structure of a dual-optical-path cold mirror dew point meter according to an embodiment of the present invention;

[0058] Figure 2 This is a schematic flowchart of a method for measuring dew point using a dual-path cold mirror dew point meter, as described in an embodiment of the present invention. Detailed Implementation

[0059] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0060] A specific embodiment of the present invention discloses a dual-optical-path cooled mirror dew point meter, such as... Figure 1 As shown, the dew point meter includes:

[0061] It consists of a light-emitting diode, three convex lenses, a beam splitter, a mirror, a temperature sensor, a measuring cavity, two silicon photovoltaic cell receiving modules, an AD conversion module, and a control board.

[0062] Furthermore, the dew point meter's measuring chamber is divided into two cavities of the same size: a reference cavity and a measuring cavity, separated by an opaque temperature balancing plate. This maintains the same temperature in both cavities and isolates them from light, ensuring that the ambient temperature of the reference cavity and the measuring cavity is the same and unaffected by fluctuations in the light source.

[0063] Furthermore, in the dew point meter, light emitted from a light-emitting diode is focused by a convex lens to a beam splitter, which then splits the light into two beams of equal intensity. One beam passes through a reference cavity and is focused by a convex lens to a silicon photodiode; this optical path is called the reference optical path. The other beam is reflected by a mirror in the measuring cavity and then focused by a convex lens to another silicon photodiode; this optical path is called the main optical path.

[0064] Specifically, the reference optical path voltage is the voltage generated when the reference optical path beam is received by the reference optical path silicon photovoltaic cell receiving module, converted into a reference optical path voltage by the AD conversion module, and then transmitted to the control board.

[0065] The main optical path voltage is the voltage generated when the main optical path beam is received by the main optical path silicon photovoltaic cell receiving module, converted into a main optical path voltage by the AD conversion module, and then transmitted to the control board.

[0066] In this embodiment, the silicon photovoltaic cell receiving module is a device used to convert optical signals into voltage signals. The AD conversion module is an analog-to-digital converter used to convert the voltage signals converted by the silicon photovoltaic cell receiving module into digital signals for control on the control board.

[0067] Furthermore, the measuring cavity is connected to a refrigerator, and the temperature of the measuring cavity is adjusted by the refrigerator; in this embodiment, the refrigerator can cool down to -80 degrees Celsius.

[0068] Furthermore, a temperature sensor is connected to the mirror surface of the measuring cavity to obtain the temperature of the measuring cavity; the other side of the temperature sensor transmits the data to the control board via a 232 serial port.

[0069] Specifically, the gas to be measured enters the measuring cavity through the inlet channel on the measuring chamber, and after being reflected by the mirror, it leaves the measuring cavity through the outlet channel on the measuring chamber.

[0070] In this embodiment, the working principle of the dual-optical-path cold mirror dew point meter is as follows: the light emitted by the light source is reflected by the mirror and converted into a voltage signal by the silicon photovoltaic cell. If the mirror is clean and free of debris, total emission occurs on the mirror.

[0071] Specifically, no mirrors are set in the reference optical path to simulate total internal reflection.

[0072] Furthermore, the measurement cavity in the main optical path is cooled by the refrigerator, while the gas being measured flows over the mirror. When the mirror temperature reaches the dew point temperature of the gas being measured, the moisture in the gas will remain on the mirror in the form of water or frost. Total internal reflection on the mirror becomes diffuse emission. At this time, the voltage signal of the receiving element in the main optical path measurement system changes drastically and locks the temperature of the mirror at this time, which is the dew point temperature of the gas being measured.

[0073] It should be noted that blowing the gas to be tested at a certain angle towards the mirror surface of the measuring cavity not only ensures normal testing but also cleans the mirror surface, avoiding measurement errors caused by dirt on the mirror surface.

[0074] Another embodiment of the present invention discloses a method for measuring dew point based on a dual-optical-path cold mirror dew point meter, such as... Figure 2 As shown, it includes the following steps:

[0075] Step S1: Pre-cool the measuring chamber of the dew point meter; wherein the measuring chamber of the dew point meter is divided into a reference chamber and a measuring chamber with the same ambient temperature.

[0076] Specifically, the pre-cooling process includes the following steps:

[0077] The temperature of the measuring cavity is collected in real time, and gas is blown into the measuring cavity.

[0078] When the temperature of the measuring cavity is greater than or equal to the set temperature threshold, the temperature of the measuring cavity is reduced to the lowest value of the dew point meter's measurement range, and then the temperature of the measuring cavity is increased until the main optical path voltage is equal to the reference optical path voltage.

[0079] It should be noted that the lowest temperature that the measuring chamber can reach is the lowest temperature that the refrigerator can cool.

[0080] When the measured temperature is lower than the set temperature threshold, the temperature of the measuring cavity is increased until the main optical path voltage is equal to the reference optical path voltage.

[0081] In this embodiment, the set temperature threshold is 0 degrees Celsius, and the lowest temperature measured by the dew point meter is -80 degrees Celsius.

[0082] Furthermore, obtaining the dew point temperature includes:

[0083] Lower the temperature of the measuring cavity;

[0084] The reference optical path voltage and the main optical path voltage are continuously acquired, and the reference optical path voltage and the main optical path voltage are calculated using anti-pulse interference averaging filter.

[0085] The difference between the reference optical path voltage and the main optical path voltage is obtained;

[0086] When the difference equals the set dew point threshold, the temperature of the measuring cavity is the dew point temperature.

[0087] The process of lowering the temperature of the measuring cavity includes controlling the refrigerator connected to the measuring cavity to slowly and uniformly lower the temperature of the measuring cavity until the main optical path voltage changes drastically, i.e., the dew point temperature is reached, and then the cooling is stopped.

[0088] Specifically, the continuous acquisition of reference optical path voltage and main optical path voltage multiple times, using anti-pulse interference averaging filter, includes:

[0089] The reference optical path voltage and the main optical path voltage are continuously collected several times, and the maximum and minimum values ​​are removed respectively, and the average value of the remainder is taken.

[0090] After multiple averaging processes, the maximum and minimum values ​​of the average values ​​of the reference optical path voltage and the main optical path voltage are removed, and then the average values ​​are taken again to obtain the final reference optical path voltage and main optical path voltage.

[0091] In this embodiment, the optical path voltage is sampled once every 10ms, and the reference optical path voltage and the main optical path voltage are sampled at least 12 times; the average value is calculated at least 5 times.

[0092] It should be noted that during dew point measurement, many complex practical factors can cause interference signals in the acquired photoelectric differential signal, which are detrimental to dew point identification. The sources of these interference signals mainly include fluctuations in the photoelectric device itself, fluctuations caused by the vibration of the refrigerator, and noise from the amplifier circuit and the AD converter itself. Simultaneously, temperature changes and minor variations in the mechanical structure fixing the photoelectric device can also cause fluctuations in the differential signal. Temperature and mechanical structure changes introduce low-frequency noise signals, while the switching power supply, photoelectric device, and electronic components introduce high-frequency noise.

[0093] Specifically, mean filtering involves sampling the signal multiple times and then averaging the results. Increasing the number of samples improves signal resolution and reduces the impact of interference.

[0094] It should be noted that although mean filtering can remove some low-frequency and high-frequency noise, the over-averaging curve is considered smooth and the dew point temperature can shift, causing measurement errors. Therefore, the mean filtering method is not entirely suitable for the algorithm of high-precision dew point meters.

[0095] Furthermore, the least squares method, by utilizing redundant metrics and aiming to minimize the sum of squared residuals, can find the optimal fitting curve or parameters. The least squares fitting function not only provides the results of data fitting but also offers guidance on data characteristics and patterns.

[0096] Step S3: The dew point temperature is compensated and corrected using a correction function to obtain the corrected dew point temperature; wherein, the correction function is obtained by using a dew point adjustable gas generator to output gas with a known dew point temperature and measuring it, and then fitting it using the least squares method.

[0097] Furthermore, the steps for obtaining the correction function include:

[0098] The temperature range of the dew point meter is divided into multiple temperature zones;

[0099] Several temperature values ​​are randomly selected within each temperature range, and the corresponding dew point temperature gas is blown out using the dew point adjustable gas generator as the dew point standard value.

[0100] The dew point temperature of the gas blown out by the dew point adjustable gas generator is measured using the dew point meter as the dew point measurement value.

[0101] By subtracting the standard dew point value from the measured dew point value, several difference values ​​are obtained;

[0102] Using the measured dew point value as the independent variable and the difference between the standard dew point value and the measured dew point value as the dependent variable, a polynomial fitting is performed using the least squares method to obtain the least squares fitting function as the correction function.

[0103] Specifically, the dew point adjustable gas generator can be set to output gases with different dew point temperatures. The dew point varies depending on the moisture content of the gas. The dew point adjustable gas generator can be set to output gases with different dew points by adjusting the moisture content of the gas.

[0104] In this embodiment, the dew point meter is capable of measuring dew points from 0 to -80 degrees Celsius, divided into multiple intervals: 0 to -10 degrees Celsius, -10 to -20 degrees Celsius, ... -70 to -80 degrees Celsius. Any temperature value can be selected within each interval; for example, in the 0 to -10 degree Celsius interval, three temperatures are selected: -3 degrees Celsius, -6 degrees Celsius, and -9 degrees Celsius. For -3 degrees Celsius, an adjustable dew point gas generator is used to set the dew point to -3 degrees Celsius. The generator then outputs gas with a dew point of -3 degrees Celsius, which is the standard dew point value. The value measured by the dew point meter is the measured dew point value.

[0105] Furthermore, the least squares fitting function is calculated through the following steps:

[0106] Step S11: Let the fitting polynomial be as follows:

[0107]

[0108] Where x is the independent variable; y is the dependent variable; k is a constant; a k For coefficients;

[0109] Step S12: Calculate the sum of the distances from each point to the curve, i.e., the sum of squared errors, as follows:

[0110]

[0111] Where i is the number of selected temperature values.

[0112] Step S13: According to the least squares principle, calculate a. i Partial derivatives:

[0113]

[0114] Step S14: Simplify and transform into matrix form as follows:

[0115]

[0116] Step S15: Solve the linear equation to obtain the coefficients a. k Substituting the fitting polynomial from step S11, we obtain the final correction function.

[0117] Step S4: Increase the cavity temperature and repeatedly measure the dew point temperature N times. Calculate the average of the N corrected dew point temperatures as the final dew point temperature; where N is an integer greater than or equal to 2.

[0118] Furthermore, the dew point temperature of the gas being measured is continuously measured. When the difference between at least three consecutive dew point temperatures is less than or equal to a set dew point accuracy threshold, the average of the dew point temperatures is taken as the final dew point temperature.

[0119] Specifically, in this embodiment, the dew point accuracy threshold is set to 0.2 degrees Celsius. The difference between three consecutive dew point temperatures is calculated, and the average of the three differences is less than or equal to 0.2 degrees Celsius, which is then taken as the final dew point temperature.

[0120] This invention employs a dual-optical-path technique, using a beam splitter to divide the light source into two identical light sources. These light sources pass through a reference cavity and a measurement cavity, respectively, ensuring that the optical paths are essentially consistent. This avoids the influence of light source fluctuations and environmental changes on the measurement results, thus improving the accuracy of dew point measurement. Pre-cooling before measurement shortens the measurement time, and the moisture in the air condenses into frost during the pre-cooling process. This frost is then carried out of the measurement cavity by the gas being measured during the pre-cooling and heating phase, preventing the influence of moisture in the air within the measurement cavity on the measurement results. Finally, the measurement results are corrected using a fitting function, further reducing noise interference and improving the accuracy of the measurement results.

[0121] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for measuring dew point using a dual-path cold mirror dew point meter, characterized in that, Includes the following steps: Step S1: Pre-cool the measuring cavity of the dew point meter; wherein, the measuring cavity of the dew point meter is divided into a reference cavity and a measuring cavity with the same ambient temperature; the measuring cavity is divided into a reference cavity and a measuring cavity of the same size, separated by an opaque temperature balancing plate to maintain the same temperature in the two cavities and isolate light; the light emitted by the light-emitting diode of the dew point meter is focused by a convex lens to a beam splitter, and split into two beams of the same intensity by the beam splitter; the reference optical path is that one beam passes through the reference cavity and is focused by a convex lens to a silicon photodiode; the main optical path is that the other beam passes through the beam splitter, is reflected by the mirror surface of the measuring cavity, and is focused by a convex lens to another silicon photodiode; The pre-cooling operation includes: real-time acquisition of the temperature of the measuring cavity and blowing gas into the measuring cavity; when the temperature of the measuring cavity is greater than or equal to a set temperature threshold, lowering the temperature of the measuring cavity to the lowest value of the dew point meter's measurement range, and then raising the temperature of the measuring cavity until the main optical path voltage is equal to the reference optical path voltage; when the measured temperature is less than the set temperature threshold, raising the temperature of the measuring cavity until the main optical path voltage is equal to the reference optical path voltage. Step S2: The gas to be measured is blown into the measuring cavity to cool the measuring cavity. The reference optical path voltage and the main optical path voltage are collected in real time and the difference is calculated. The dew point temperature is determined based on the pressure difference, including: Lower the temperature of the measuring cavity; The reference optical path voltage and the main optical path voltage are continuously acquired, and the reference optical path voltage and the main optical path voltage are calculated using anti-pulse interference averaging filter. The difference between the reference optical path voltage and the main optical path voltage is obtained; when the difference is equal to the set dew point threshold, the temperature of the measuring cavity is the dew point temperature. Step S3: Compensate and correct the dew point temperature using a correction function to obtain the corrected dew point temperature; wherein, the correction function is obtained by using a gas with a known dew point temperature output by an adjustable dew point gas generator, measuring the gas, and then fitting the measurement using the least squares method, including: The measurement range is divided into multiple temperature zones; Several temperature values ​​are randomly selected within each temperature range, and the corresponding dew point temperature gas is blown out using the dew point adjustable gas generator as the dew point standard value. The dew point temperature of the gas blown out by the dew point adjustable gas generator is measured using the dew point meter as the dew point measurement value. By subtracting the standard dew point value from the measured dew point value, several difference values ​​are obtained; Using the measured dew point value as the independent variable and the difference between the standard dew point value and the measured dew point value as the dependent variable, a polynomial fitting is performed using the least squares method to obtain a least squares fitting function as a correction function; wherein, the least squares fitting function is calculated through the following steps: Step S11: Let the fitting polynomial be as follows: ； in, x As the independent variable; y The dependent variable; k It is a constant; For coefficients; Step S12: Calculate the sum of the distances from each point to the curve, i.e., the sum of squared errors, as follows: in, i The number of selected temperature values; Step S13: According to the least squares principle, calculate... Partial derivatives: Step S14: Simplify and transform into matrix form as follows: Step S15: Solve the linear equation to obtain the coefficients. Substitute the fitting polynomial from step S11 into the final correction function; Step S4: Increase the cavity temperature and repeat the measurement N times. Calculate the average of the corrected dew point temperatures N times as the final dew point temperature; where N is an integer greater than or equal to 2.

2. The method according to claim 1, characterized in that, The continuous acquisition of reference optical path voltage and main optical path voltage multiple times, using anti-pulse interference averaging filter, includes: The reference optical path voltage and the main optical path voltage are continuously collected several times, and the maximum and minimum values ​​are removed respectively, and the average value of the remainder is taken. After multiple averaging processes, the maximum and minimum values ​​of the average values ​​of the reference optical path voltage and the main optical path voltage are removed, and then the average values ​​are taken again to obtain the final reference optical path voltage and main optical path voltage.

3. The method according to claim 1, characterized in that, The step of taking the average of the corrected dew point temperatures as the final dew point temperature includes: continuously measuring the dew point temperature of the gas being measured, and taking the average of the dew point temperatures as the final dew point temperature when the difference between at least three consecutive dew point temperatures is less than or equal to a set dew point accuracy threshold.

4. The method according to claim 1, characterized in that, The reference optical path voltage is the voltage generated by the reference optical path silicon photovoltaic cell receiving module after the reference optical path beam is received by the reference optical path silicon photovoltaic cell receiving module and converted into a reference optical path voltage by the AD conversion module and then transmitted to the control board. The main optical path voltage is the voltage generated when the main optical path beam is received by the main optical path silicon photovoltaic cell receiving module, converted into a main optical path voltage by the AD conversion module, and then transmitted to the control board.

5. The method according to claim 4, characterized in that, The measuring cavity is connected to a refrigerator and a temperature sensor; the temperature of the measuring cavity is adjusted by the refrigerator; the temperature of the measuring cavity is obtained by the temperature sensor. One side of the temperature sensor is connected to the mirror surface in the measuring cavity, and the other side transmits data to the control board via a 232 serial port.

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