Multi-gas detection device and method based on cavity ring-down spectroscopy technology

Abstract

The invention provides a multi-gas detection device and method based on an optical cavity ring-down spectroscopy technology, and relates to the technical field of gas concentration detection, the device comprises a laser generation module, a resonant cavity, a gas inlet and outlet module and a signal acquisition module; the laser generation module comprises an optical switch and a plurality of lasers with set laser emission wavelengths; the laser emission wavelength of each laser is the wavelength with the highest absorption intensity of the corresponding to-be-detected gas; the input end of the optical switch is connected with the output end of each laser, and the output end of the optical switch is connected with the resonant cavity for arranging a laser valve output by one laser into the resonant cavity; the gas inlet and outlet module is connected with the resonant cavity and is used for inputting gas to be detected into the resonant cavity; and the signal acquisition module is connected with the output end of the resonant cavity and is used for acquiring the ring-down light signal output by the resonant cavity to obtain a gas detection result. According to the invention, efficient interval detection of various gases can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of gas concentration detection, and particularly to a multi-gas detection device and method based on cavity ring-down spectroscopy technology. Background Art

[0002] Carbon dioxide (CO 2 ) and methane (CH 4 ) are the main greenhouse gases in the atmosphere, which have an increasingly profound impact on global climate change. Excessively high concentrations of carbon dioxide and methane in the atmosphere not only affect the greenhouse effect, but also cause adverse effects such as damage to the ecosystem and extreme climate. At the same time, high concentrations of carbon dioxide will also reduce the indoor air quality and endanger human health, while high concentrations of methane will endanger industrial environmental safety. Therefore, accurately measuring the concentrations of carbon dioxide and methane is of great significance for studying greenhouse gas emissions, environmental and ecological protection, and industrial safety, etc.

[0003] As a newly emerging high-sensitivity absorption spectroscopy detection technology, cavity ring-down spectroscopy (CRDS) technology, compared with traditional detection methods such as gas chromatography and gas analyzer methods, greatly improves the detection sensitivity of trace gases by virtue of the ultra-long optical path formed by multiple reflections of light in a high-reflectivity resonant cavity. However, although it has significant advantages in detection sensitivity, the existing gas concentration detection using CRDS technology usually can only detect a single gas, with low detection efficiency. At the same time, there is background noise interference in the detection process, which seriously affects the detection accuracy. Summary of the Invention

[0004] In order to solve at least one deficiency of the prior art, the purpose of the present invention is to provide a multi-gas detection device and method based on cavity ring-down spectroscopy technology to achieve interval detection of multiple gases, meet the diverse needs of gas detection, and improve the detection efficiency.

[0005] To achieve the above purpose, according to some embodiments, in the first aspect of the present invention, there is provided a multi-gas detection device based on cavity ring-down spectroscopy technology, including a laser generation module, a resonant cavity, an air inlet and outlet module, and a signal acquisition module;

[0006] The laser generation module includes an optical switch and multiple lasers with set laser emission wavelengths; the laser emission wavelength of each laser is the wavelength with the highest absorption intensity for the corresponding gas to be detected; the input end of the optical switch is connected to the output ends of the lasers, and the output end of the optical switch is connected to the resonant cavity, and is used to set the resonant cavity with the laser output by one laser;

[0007] The air inlet and outlet module is connected to the resonant cavity and is used to input the gas to be detected into the resonant cavity;

[0008] The signal acquisition module is connected to the output end of the resonant cavity, and is used to acquire the ring-down optical signal output by the resonant cavity to obtain the gas detection result.

[0009] Preferably, the inner wall of the resonant cavity is coated with a quartz coating.

[0010] Preferably, the air inlet and outlet module includes an air inlet module and an air outlet module; the air inlet module is connected to the air inlet of the resonant cavity and includes a filtering device and a flowmeter connected in sequence. The filtering device is used to filter the particulate matter, moisture and impurities in the inlet air; the air outlet module is connected to the air outlet of the resonant cavity and includes a pressure gauge and a vacuum pump connected in sequence.

[0011] Preferably, the laser is a DFB laser.

[0012] Preferably, the signal acquisition module includes a photodetector and a computer. The photodetector is arranged at the output end of the resonant cavity and is used to receive the transmitted optical signal. The computer is integrated with a data acquisition card and is used to be connected to the photodetector to acquire the transmitted optical signal received by the photodetector.

[0013] In the second aspect of the present invention, based on the multi-gas detection device based on the optical cavity ring-down spectroscopy technology provided in the first aspect, a multi-gas detection method based on the optical cavity ring-down spectroscopy technology is further provided, including:

[0014] Determine the laser emission wavelength of the laser according to the type of gas to be detected;

[0015] Initialize the detection device;

[0016] Set the working mode of the optical switch according to the detection task; if multiple gases are detected at intervals, the optical switch switches after reaching the set conditions;

[0017] Introduce the gas to be detected into the detection device to perform gas concentration detection.

[0018] Preferably, the initialization of the detection device includes selecting a resonant cavity matching the laser emission wavelength according to the determined laser emission wavelength, and correspondingly connecting the air inlet and outlet module and the signal acquisition module to the resonant cavity to build the detection device; debugging each component in the detection device.

[0019] Preferably, the optical switch switches after reaching the set conditions, including that the optical switch switches according to the preset interval measurement time, or when the detection result meets the stable conditions, the optical switch switches.

[0020] Preferably, when the detection result meets the stable conditions, the optical switch switches, specifically, when the change amount of the detection result is within the set range within a continuous set time or within a continuous set number of detections, the optical switch switches.

[0021] Preferably, it further includes inverting and calculating the concentration of the gas to be measured after processing the obtained attenuated transmitted optical signal, and performing temperature and / or pressure correction on the calculation result.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The present invention provides a multi-gas detection device and method based on the cavity ring-down spectroscopy technology. By designing multiple lasers in cooperation with an optical switch, it can flexibly adapt to the diverse gas detection requirements in actual scenarios. By manipulating the optical switch, it can easily achieve free switching between single-gas detections such as carbon dioxide or methane, as well as interval detections between two or more gases, and the detection intervals can be freely set. The operation is simple, it supports automated and real-time continuous measurement, and the detection efficiency is extremely high. It can complete the concentration determination of carbon dioxide and methane in a very short time (such as within a few seconds), perfectly meeting the requirements for rapid monitoring and dynamic tracking of emission sources. Therefore, it shows broad application potential and value in key fields such as industrial waste gas emission monitoring and industrial closed environment safety monitoring. In addition, the present invention filters out particulate matter, moisture, and impurities in the intake air through drying and filtering of the intake air, especially drying the gas, effectively weakening the interference of moisture in the detection ambient air on the gas measurement results and improving the detection accuracy.

[0024] The advantages of the additional aspects of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The schematic diagrams in the specification drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0026] Figure 1 It is a schematic diagram of a multi-gas detection device based on the cavity ring-down spectroscopy technology provided in Embodiment 1 of the present invention;

[0027] Figure 2 It is a schematic diagram of the detection signal acquisition process;

[0028] Figure 3 It is a schematic diagram of the signal processing process. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present invention will be further described below in conjunction with the drawings and embodiments.

[0030] Embodiment 1

[0031] Embodiment 1 of the present invention is as Figures 1-3As shown in the figure, a multi-gas detection device based on cavity ring-down spectroscopy technology is provided, which includes a laser generation module, a resonant cavity, an intake and exhaust module, and a signal acquisition module;

[0032] The laser generation module includes an optical switch and multiple lasers with set laser emission wavelengths; the laser emission wavelength of each laser is the wavelength corresponding to the highest absorption intensity of the gas to be detected; the input end of the optical switch is connected to the output ends of the lasers, and the output end of the optical switch is connected to the resonant cavity, and is used to set the resonant cavity with the laser valve output by one laser;

[0033] The intake and exhaust module is connected to the resonant cavity and is used to input the gas to be detected into the resonant cavity;

[0034] The signal acquisition module is connected to the output end of the resonant cavity and is used to obtain the ring-down optical signal output by the resonant cavity to obtain the gas detection result.

[0035] In response to the challenges of insufficient detection interval and detection accuracy and serious background noise interference in the detection of the concentrations of multiple gases in the environment at the same time. On this basis, in this embodiment, multiple lasers with different wavelengths are innovatively added to the cavity ring-down spectroscopy (CRDS) technology to detect gas concentration, and an optical switch is added for switching, and software is used for switching control. A gas drying scheme is introduced, which effectively weakens the interference of moisture in the detected ambient air on the measurement results of the two gases. The device can quickly and accurately measure the concentrations of multiple gases, and can realize the customizable switching of the gas detection interval time, greatly improving the flexibility and suitability of gas detection. This progress provides more convenient technical support for multiple fields such as environmental monitoring, climate change research, and industrial safety. For the convenience of description, the following takes the detection of two gases, carbon dioxide and methane, as an example to illustrate this embodiment.

[0036] The principle of gas concentration detection based on cavity ring-down spectroscopy technology is to utilize the gradual attenuation of laser intensity caused by the gas in the resonant cavity, collect the attenuation signal and perform data analysis and processing, so as to obtain the gas concentration detection result. The laser used is a DFB laser to output laser with a single wavelength. To adapt to the detection of carbon dioxide and methane, the laser emission wavelength of the laser is the wavelength corresponding to the highest absorption intensity of the gas to be detected. In this embodiment, the wavelengths of the two DFB lasers are set to 1600.5 nm and 1653.7 nm, respectively, for detecting the concentrations of carbon dioxide and methane. At the same time, in this process, the control of the optical switch that controls the output of the two lasers is integrated into the circuit board, and gas detection software is used for control to realize single-gas measurement and interval measurement of the two gases based on actual target requirements, and realize the custom setting of the detection interval, so as to meet the flexible measurement requirements based on actual needs. During the measurement process, the captured attenuation signal is analyzed through a specific algorithm to accurately measure the concentration of the measured gas.

[0037] The laser is connected to a laser driver. The laser driver is an electronic device used to control and supply the required electric power for the laser. Its main function is to provide precise current or voltage for the laser to ensure that the laser can work stably and efficiently and can quickly respond to operation instructions when needed. Two precisely regulated DFB lasers have their emission wavelengths accurately locked at 1600.5 nm and 1653.7 nm respectively, and the output power is constantly maintained at the 20 mW level. With their ultra-narrow linewidth characteristics (<2 MHz) and side mode suppression ratio (SMSR) of up to 40 dB, these lasers exhibit excellent stability and monochromaticity at an operating current of 80 mA, and the wavelength tolerance is precisely controlled within the range of ±1 nm. This provides a stable and finely adjustable wavelength laser light source basis for the high-precision detection of carbon dioxide and methane gases.

[0038] The input end of the optical switch is connected to two DFB lasers, and the output end is connected to the resonant cavity via an optical fiber collimator, which is used to switch the connection state between the two DFB lasers and the resonant cavity.

[0039] The resonant cavity adopts a carefully designed 50 cm long ring-down cavity with a quartz coating on its inner wall, which effectively suppresses the adsorption of gas molecules on the cavity wall, thereby reducing the measurement error. For the cavity mirrors, two plano-concave high-reflectivity mirrors with a diameter of 25.4 mm and a radius of curvature of 100 cm are selected. These mirrors have a reflectivity of up to 99.9963% in the wavelength range of 1600 nm to 1700 nm. These cavity mirrors are installed on a three-dimensional mirror mount with high-precision adjustment. Through fine adjustment, the perfect matching between the laser mode and the cavity mode is ensured, thereby improving the coupling efficiency and resonance efficiency of light in the cavity.

[0040] The signal acquisition module integrates a high-sensitivity photodetector, a high-speed and high-precision data acquisition card, and a dedicated PC-side data processing software. The photodetector is optimized specifically for the wavelengths of 1600.5 nm and 1653.7 nm and can accurately capture the transmitted light signal. Once the transmitted light intensity reaches the preset threshold, the detector will quickly send a signal to the trigger board to stop the laser from working. At this time, the light signal in the cavity begins to decay naturally. With its high-speed sampling rate and high resolution, the data acquisition card can accurately record the decay signal output by the photodetector. The PC side runs specially developed software to perform real-time processing, in-depth analysis, and accurate calculation on the collected data, and finally obtains the gas concentration value.

[0041] The intake and exhaust module includes an intake module and an exhaust module. The intake module includes a filtering device and a flowmeter connected in sequence, and is connected to the intake port of the resonant cavity through a gas pipeline. The exhaust module includes a pressure gauge and a vacuum pump connected in sequence, and is connected to the exhaust port of the resonant cavity through a gas pipeline. In addition, a thermometer can be provided on the gas pipeline to monitor the temperature inside the gas pipeline. The flowmeter can accurately regulate the gas flow entering the resonant cavity to ensure the stable input of gas samples. The vacuum pump is responsible for maintaining the air pressure stability in the gas pipeline system and promoting the uniform distribution of gas in the cavity. The thermometer and the pressure gauge monitor the temperature and air pressure changes in the gas pipeline in real time, providing the necessary calibration data for subsequent concentration calculations.

[0042] Use PyCharm to simulate the spectral data of HITRAN, and use Microsoft Visual Studio to calculate the real-time concentrations of carbon dioxide and methane.

[0043] Example Two

[0044] Based on the multi-gas detection device based on the optical cavity ring-down spectroscopy technology provided in Example One, this example further provides a multi-gas detection method based on the optical cavity ring-down spectroscopy technology, including:

[0045] Step S1: Determine the laser emission wavelength of the laser according to the type of gas to be measured;

[0046] Step S2: Initialize the detection device;

[0047] Step S3: Set the working mode of the optical switch according to the detection task; if detecting multiple gases at intervals, the optical switch switches after reaching the set conditions;

[0048] Step S4: Pass the gas to be measured into the detection device to detect the gas concentration.

[0049] In Step S1, use the data in the HITRAN spectral database to simulate the absorption wavelength ranges of carbon dioxide and methane gases, and exclude the influence and absorption interference of other gases. Specifically, it includes:

[0050] Step S11: According to the HITRAN spectral database, use python to draw the relationship diagram between the absorption intensity and wavelength of carbon dioxide and methane gases, select the stronger absorption spectral lines, and ensure that there is no interference from other gases near the selected wavelengths;

[0051] Step S12: Through the absorption spectral line image, select the corresponding wavelengths with higher absorption intensities of carbon dioxide gas and methane, and determine the wavelengths of the two DFB lasers to be 1600.5 nm and 1653.7 nm. Then, according to the emission wavelengths of the two selected lasers, select a resonant cavity with a cavity mode matching the two laser modes for matching to build a gas detection system.

[0052] In step S2, it specifically includes:

[0053] S21. According to the wavelengths of the two selected DFB lasers, select a resonant cavity with a cavity mode that can match the two laser modes for combination, and build a gas detection system;

[0054] S22. Initialize and debug the parameters of each part of the CRDS system, and check whether the system can operate normally;

[0055] S23. Check the effectiveness and tightness of the intake and outlet systems, and check whether the signal trigger and photodetector can work normally.

[0056] In step S21, it specifically includes:

[0057] Step S211. Install the laser on a stable bracket with good heat dissipation performance to ensure the stability of its working temperature;

[0058] Step S212. Select a resonant cavity composed of a plano-concave high reflector with a reflectivity of 99.9963% in the wavelength range of 1600 - 1700 nm to achieve the best matching of the laser modes of the two lasers and the cavity mode;

[0059] Step S213. Connect the photodetector to the output port of the resonant cavity to receive the transmitted light signal after gas absorption;

[0060] Step S214: Connect the signal output by the photodetector to a high-speed and high-precision data acquisition card, and use the data acquisition card to monitor and record these signal data in real time;

[0061] Step S215: The data acquisition card is integrated into the PC side, and the collected signals are processed and analyzed by running special software;

[0062] Step S216: Assemble an intake filter (filter device), intake proportional valve, flow meter, pressure gauge, vacuum pump and connecting pipes to form a complete gas path system. Ensure the stability of the air flow during system operation, and effectively remove particulate matter, moisture and other impurities in carbon dioxide gas.

[0063] In step S22, it specifically includes:

[0064] Step S221. Preheat two distributed feedback (DFB) lasers, continuously monitor their temperature changes, and adjust the working temperature of the lasers to ensure that they are within the normal working range of the best performance;

[0065] Step S222: Start the control software of the data acquisition card on the computer (PC) side, and set the sampling frequency to 1 GHz in the software to meet the requirements of high-precision data acquisition;

[0066] Step S223: Execute the calibration program of the data acquisition card to ensure that the collected signals are accurate and improve the reliability of the data;

[0067] Step S224: Calibrate the acquisition card to ensure that the collected signals are accurate;

[0068] Step S225: Check whether the data is saved to avoid data loss.

[0069] In step S23, it specifically includes:

[0070] Step S231: Before formally detecting the gas, first fill the detection chamber with nitrogen, and adjust the flow rate and pressure of nitrogen to ensure the stability of the internal environment of the chamber;

[0071] Step S232: During the intake process of nitrogen or the gas to be measured, continuously monitor the flow rate and pressure of the gas, and precisely adjust the intake proportional valve through a real-time feedback mechanism to keep the gas flow rate within the range of ±5% of the preset value, and at the same time ensure that the pressure fluctuation does not exceed ±0.001 atm to guarantee the accuracy of the detection results;

[0072] Step S233: Use an oscilloscope to debug the trigger signal of the driving circuit of the laser. This step aims to ensure that the laser can work normally according to the predetermined timing and control instructions, providing a stable light source for subsequent gas detection;

[0073] Step S234: When the detection chamber is in the cavity state, collect the output signal of the photodetector, and determine the threshold size for triggering data acquisition according to the characteristics of the collected signal, providing accurate triggering conditions for subsequent gas concentration detection;

[0074] Step S235: During the detection process, continuously monitor the output signal of the photodetector. When the signal reaches the preset trigger threshold, automatically trigger the data acquisition system to start recording data, and at the same time perform analysis and verification to ensure the accuracy of the results.

[0075] In step S3, adjust the mode of the optical switch to control whether the working mode of the CRDS device is single-gas measurement or two or more gas interval measurements, and the time of interval measurement can be customized. Taking the detection of carbon dioxide and / or methane as an example, it includes:

[0076] Step S31: Open the gas detection software, open the setting interface, and select the working mode as single carbon dioxide gas measurement, single methane gas measurement, or carbon dioxide and methane interval measurement;

[0077] Step S32: If it is selected to measure carbon dioxide and methane at intervals, set the time for interval measurement, which can be determined according to actual needs. By default, the measurement is changed every 15 minutes. Since the optical switch can achieve fast switching, for multi-gas detection in a specific environment, such as an indoor environment, a short interval time can be set to achieve continuous measurement. In addition, the interval measurement can also be set to meet specific conditions. For example, when the measurement of one gas is stable, switch to another gas. At this time, the stable conditions can be preset, and when the detection result meets the stable conditions, the optical switch is switched. The stable adjustment can be set as follows: when the detection result changes within a set range within a continuous set time (for example, one minute) or within a continuous set number of detection times (for example, the variance of several consecutive measurement results is lower than the set threshold), it means that the detection result is stable and the concentration of the gas to be detected is also in a stable state. Then, the optical switch can be switched to detect another gas. This method can, on the one hand, achieve continuous and efficient detection of multiple gases, and on the other hand, when the concentration of one gas fluctuates greatly, it will not miss the detection data and can timely discover and record abnormal data.

[0078] In step S4, it includes: S41: Introduce the gas to be detected in the environment into the system for real-time detection, and save the attenuation signals of different gases in different bin files in real time; specifically including:

[0079] Step S411: In the initial stage, fill the internal space of the resonator with nitrogen to create a reference environment without the gas to be detected. In this nitrogen-filled state, start the data acquisition system, collect and record the cavity ring-down optical signal at this time as the reference data for subsequent analysis.

[0080] Step S412: Start the intake device, and introduce the gas to be detected in the environment into the resonator through the designed gas path system, and ensure the smooth and uniform flow of the gas.

[0081] Step S413: On the PC side, open the laser driver through the gas detection software interface to generate a trigger signal.

[0082] Step S414: Carefully observe the ring-down optical signal collected by the data acquisition system, check whether there are obvious interference or distortion phenomena in the signal and adjust it in time.

[0083] Step S415: Check the generated.bin format data file to confirm that the ring-down optical signal has been correctly and completely saved.

[0084] In addition, after the data acquisition in step S41 is completed, it also includes: S42: Further process and analyze the collected data, and accurately determine the concentrations of carbon dioxide and methane by inverting the attenuation signal. Specifically including:

[0085] Step S421, data preprocessing: Process the attenuation signals saved in the same bin file, perform baseline correction on each attenuation signal to eliminate the influence of background noise, and perform denoising processing to improve the signal-to-noise ratio of the signal;

[0086] Step S422, signal fitting and parameter extraction: Construct a suitable fitting model for the attenuation signal, and extract the time corresponding to when the attenuation signal decays to 1 / e of its maximum value, that is, the 1 / e decay time;

[0087] Step S423, using the concentration calculation formula, combined with the 1 / e decay time extracted in Step S422, call the inversion program of the corresponding gas according to the working mode of the selected CRDS instrument to calculate the concentration of the measured gas, and perform necessary temperature and pressure corrections on the calculated concentration values to improve the accuracy of the measurement results;

[0088] Step S424, display the real-time calculated carbon dioxide and methane concentration values on the PC interface for easy monitoring and recording. At the same time, save these concentration values and their corresponding time information in a txt file for subsequent data analysis and processing.

[0089] In Step S421, it specifically includes:

[0090] Step S4211, using digital signal processing technology, first correct the DC offset in the signal to ensure that the baseline of the attenuation signal can be adjusted to a level close to zero, thereby eliminating the influence of baseline offset on subsequent analysis;

[0091] Step S4212, in order to further improve the signal-to-noise ratio of the signal, use the moving average filtering method to smooth the attenuation signal, effectively weaken the random noise in the signal, and provide a clearer and more accurate signal basis for subsequent data analysis.

[0092] In Step S422, it specifically includes:

[0093] Step S4221, use the fitting algorithm to perform fitting processing on the filtered and denoised attenuation signal;

[0094] Step S4222, use the least squares method to fit the signal data to this exponential decay function;

[0095] Step S4223, through optimizing the extraction algorithm, extract the ring-down time τ value when the value is 1 / e of the maximum value;

[0096] Step S4224, in order to obtain more accurate comparison data, perform baseline correction and denoising processing on the attenuation signal in the cavity state to ensure the purity and consistency of the data;

[0097] Step S4225: Finally, through the same fitting and extraction algorithm process, extract the time point corresponding to the signal attenuation to 1 / e of its maximum value in the cavity state, denoted as the τ0 value.

[0098] In step S423, it specifically includes:

[0099] Step S4231: Determine that the absorption cross-section σ(λ) of carbon dioxide gas is approximately 1.16×10 -24 cm 2 / mol through the wavelength λ = 1600.5 nm. Determine that the speed of light c in the ring-down cavity is 2.99792458×10 10 cm / s, and the Avogadro constant N A is 6.02214076×10 23 . Determine that the absorption cross-section σ(λ) of methane gas is 3.5×10 - 21 cm 2 / mol through the wavelength λ = 1653.7 nm. Determine that the speed of light c in the ring-down cavity is

[0100] 2.99792458×10 10 cm / s, and the Avogadro constant N A is 6.02214076×10 23 ;

[0101] Step S4232: Call the inversion programs of carbon dioxide gas and methane gas according to the selected working mode, and calculate the concentration value of the measured gas through the formula and the two extracted ring-down times;

[0102] Step S4233: After completing one measurement, the system will automatically enter the next measurement to achieve continuous monitoring of the measured concentration;

[0103] Step S4234: Combine the temperature and pressure data measured by the thermometer and pressure gauge in the gas path module to correct the concentration data.

[0104] In step S424, it specifically includes:

[0105] Step S4241: On the PC-side gas detection software interface, display the carbon dioxide concentration data obtained through acquisition in real time for immediate monitoring;

[0106] Step S4242: The software interface can generate and display a trend graph of the carbon dioxide concentration changing with time to help users intuitively understand the dynamic fluctuations of the concentration;

[0107] Step S4243: To ensure the traceability and security of data, the processed data is saved in a folder named after the date in the format of a txt file, and each file is named after its corresponding measurement time for convenient subsequent data management and analysis;

[0108] Step S4244: In addition, a data index file is specifically established, which details the storage location of each measurement data, the specific measurement time, and the relevant parameter information, providing a convenient data retrieval method for users.

[0109] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multi-gas detection device based on cavity ring-down spectroscopy technology, characterized in that: It includes a laser generation module, a resonant cavity, an air inlet and outlet module, and a signal acquisition module; The laser generation module includes an optical switch and a plurality of lasers with set laser emission wavelengths; the laser emission wavelength of each laser is the wavelength corresponding to the highest absorption intensity of the gas to be measured; the input end of the optical switch is connected to the output end of each laser, and the output end of the optical switch is connected to the resonant cavity, which is used to set the resonant cavity for the laser valve output by a laser; An air inlet and outlet module is connected to the resonant cavity and is used to input the gas to be measured into the resonant cavity; The signal acquisition module is connected to the output end of the resonant cavity and is used to obtain the ring-down light signal output by the resonant cavity to obtain the gas detection result.

2. The multi-gas detection device based on cavity ring-down spectroscopy technology according to claim 1, characterized in that: The inner wall of the resonant cavity is covered with a quartz coating.

3. The multi-gas detection device based on cavity ring-down spectroscopy technology according to claim 1, characterized in that: The air inlet and outlet module includes an air inlet module and an air outlet module; the air inlet module is connected to the air inlet of the resonance cavity, and includes a filter device and a flow meter connected in sequence, and the filter device is used to filter particulate matter, moisture and impurities in the intake air; the air outlet module is connected to the air outlet of the resonance cavity, and includes a pressure gauge and a vacuum pump connected in sequence.

4. The multi-gas detection device based on cavity ring-down spectroscopy technology according to claim 1, characterized in that: The laser is a DFB laser.

5. The multi-gas detection device based on cavity ring-down spectroscopy technology according to claim 1, characterized in that: The signal acquisition module includes a photodetector and a computer. The photodetector is arranged at the output end of the resonant cavity and is used to receive the transmitted light signal. The computer is integrated with a data acquisition card and is used to connect to the photodetector to obtain the transmitted light signal received by the photodetector.

6. A multi-gas detection method based on cavity ring-down spectroscopy technology, characterized in that: A multi-gas detection device based on cavity ring-down spectroscopy technology according to any one of claims 1 to 5, comprising: Determine the laser emission wavelength of the laser according to the type of gas to be measured; Initializing the detection device; Set the working mode of the optical switch according to the detection task; if multiple gases are detected at intervals, the optical switch will switch after the set conditions are met; The gas to be tested is passed into the detection device to detect the gas concentration.

7. The multi-gas detection method based on cavity ring-down spectroscopy technology according to claim 6, characterized in that: The initialization detection device includes, according to the determined laser emission wavelength of the laser, selecting a resonant cavity matching the laser emission wavelength, and correspondingly connecting an air inlet and outlet module and a signal acquisition module to the resonant cavity to build a detection device; and debugging each component in the detection device.

8. The multi-gas detection method based on cavity ring-down spectroscopy technology as claimed in claim 6, characterized in that: The optical switch switches after the set conditions are met. Including, the optical switch is switched according to a preset interval measurement time, or, when the detection result meets the stability condition, the optical switch is switched.

9. The multi-gas detection method based on cavity ring-down spectroscopy technology as claimed in claim 8, characterized in that: When the detection result meets the stability condition, the optical switch is switched. Specifically, when the change amount of the detection result is within a set range within a continuous set time or a continuous set number of detections, the optical switch is switched.

10. The multi-gas detection method based on cavity ring-down spectroscopy technology according to claim 6, characterized in that: The method also includes, after processing the acquired attenuated transmitted light signal, inverting and calculating the concentration of the gas to be measured, and performing temperature and / or pressure correction on the calculation result.

Images