The Research On CO₂ Detection Technology Based On Tunable Laser And Supercontinuum Laser

With the rapid development of industry,human survival environment is facing an increasingly severe challenge,CO,CO₂,SO2 pollution gas and nitrogen oxide emissions exacerbated the deterioration of the environment,so the detection of the composition and content of toxic gases and air pollution has important significance.This paper summarized some methods of detecting gas,and built tunable laser and supercontinuum laser gas detection system based on the direct absorption spectra.By the concentration and temperature of the experiment system,we analyzed the absorption signal uncertainty and detection limit parameters,and put forward a new type of laser the detection system,the specific contents are as follows:In this paper,we selected the various instruments and equipment,designed and built two experimental systems based on the principle of absorption spectroscopy technology.We based on the web version of the HITRAN database,used a central wavelength of 1430 nm laser diode as the light source of tunable laser gas detection system,and we discussed the tuning characteristics of the DFB laser,determined the optimum parameters,the working temperature of the diode laser is 49.3?,the working current is 57.6mA.We designed and redacted the data acquisition system based on the LABVIEW software,it has friendly interface,and is easy to operate.With different concentrations of 0.3%,0.5%,0.9%,1.2%,1.5%,and 2% CO₂ as the target gas,we studied the CO₂ absorption signals of the two detection systems at room temperature and pretreated the collected data.Through the verification of the fitting results,it shows that the two sets of systems are effective for the detection of carbon dioxide gas.In the experiment,the detection sensitivity and detection limit of the two sets of systems were analyzed and compared and the advantages and disadvantages of the two kinds of detection systems for the detection of trace gases are comprehensively evaluated.According to the standardization requirements and relevant data in Measurement Uncertainty Evaluation and Representation?JJF1059-2012?,the sources of measurement uncertainty in the whole experimental process were analyzed,and the uncertainty component,synthetic standard uncertainty and extended uncertainty caused by various factors were evaluated.In order to accurately measure temperature on the absorption spectrum of CO₂,we used the concentration of 8% CO₂ as the target gas,made use of supercontinuum lasers with LLTF tunable optical filter,we measured the different temperature of CO₂ absorption spectrum?1430nm-1434nm?and analyzed the difference absorption spectrum.We obtained the absorbance between 20? and 50 ? with the interval is 1°C and a good mathematical model of fitting curve and the fitting formula,this supplements and perfects the existing temperature on CO₂ absorption spectra for the absorption effect of the database,and it has important reference significance for the measurement of the practical application of CO₂.After comparing and analyzing the experimental results of two sets of gas detection system,the evaluation of the two systems in gas detection in their respective advantages and disadvantages,we analyzed and designed the new combined laser gas detection system,its working principle and operation process are described,and the experimental system of precision was designed to ensure the normal transmission of the laser optical path,these also have an important guiding significance for the follow-up research and development of gas on-line monitoring and implementation of multi-component gas online detection.