Research On Multi-component Gas Measurement System Based On FPI

Toxic and harmful gases such as the gas produced by the explosion,automobile exhaust,high-pressure insulating gas SF₆ and its decomposition products,and refrigerant leakage not only threaten people’s production and life,but also bring harm to the atmospheric environment.To minimize the hazard,it is urgent to study a multi-component gas measuring instrument to monitor the dangerous gas at the accident site.Fabry-Perot Interferometer（FPI）can make infrared light of different wavelengths interfere by changing the spacing between two interfering mirrors.By detecting and analyzing the interference spectrum,infrared light attenuation can be obtained information.Combining the infrared absorption principle of gas with the interference characteristic of FPI,this paper applies FPI to the measurement of multi-component gas.In order to study the performance of FPI in gas measurement,first of all,the principle of gas absorption and the principle of FPI interference are thoroughly studied,and the concentration fitting algorithm of FPI measurement system is proposed.Secondly,the system is designed in terms of optical path structure,system hardware and software,the appropriate light source and FPI detector are selected,the gold-plated gas chamber with extinction threads is designed,and the optical path structure design with high flux is completed;the power supply circuit is completed,Light source drive circuit without common mode conduction,adjustable voltage boost circuit,ourth-order Butterworth low-pass filter and communication module and main control chip selection to ensure the stable operation and the effective data transmission of the system hardware;designed a software test platform for data acquisition and processing based on labview with two working modes,in which the wide-band sweep mode realizes the detection and analysis of multi-component gases in the detection range of 8000 nm to10500 nm,with a single wavelength frequency mode sets a single center wavelength to achieve a single gas measurement.Finally,the measured gradient absorption rate data was used to optimize the parameters of the sensor’s concentration model,and the concentration parameter with the fitting determination coefficient R² above 0.998 was obtained,and the performance of the system was tested with refrigerant gas detection as the experimental object.Evaluation,in which the indication error is less than±6%,the repeatability is less than 2.5%,and the long-term stability is less than 3.6%.The experimental results prove that the multi-component gas measurement system based on FPI has high stability and can effectively measure a variety of refrigerant gases.The system can change the distance between the FPI interference mirrors by controlling the voltage,and selectively pass the light of different wavelengths to realize the measurement of multi-component gas within the detection range of the detector,which overcomes the previous problem of single selectivity of gas sensors.And the system can be extended to other gas measurement areas where the gas absorption peak is within the detection range of the FPI detector.