| This thesis is based on laser spectroscopy in studying low concentration of CO gasdetection. System that was designed to achieve the detection of the CO is based on theAbsorption theory, CO as a toxic gas, is not only a threat to human life and safety, but alsois a kind of air pollution. CO can cause air pollution and bring great impact on theproduction of human life. Low concentration of CO can cause a variety of non occupationof CO poisoning, because that the low CO concentration was easy to be ignored. Tostrengthen the detection of low concentration CO gas in the air, people’s health and lifesecurity can be better than before. At the same time, the concentration information of COalso provides a more objective basis in improving the air quality.Therefore, the CO gasdetection is very important.This article designs the CO monitoring system in multiple parts. It includes absorptionchamber, absorption wavelength, detection circuit. CO gas analysis model is set up on theexperimental data. This system is based on kinds of researches on current scheme in COdetection technology, and in the development situation of domestic testing equipment, atthe same time, it has made further analysis and research on it. Through the comparison ofthe gas chamber, photoelectric detector in specific module design. A reasonable designscheme is determined. Using a small transmission chamber in the state of gradientrefractive index, can improve the efficiency of light transmission and absorption process.Through the in-depth study in the theory of molecular absorption spectrum andLambert-Beer’s law, also analysis in characteristics of the CO absorption spectrum. Finally,the gas absorption wavelength is selected in1.568μm. The detection circuit uses anavalanche photodiode. Due to the avalanche effect, it can get the ideal photoelectric signal.The circuit uses MAX5026as the bias power supply, with OPA276and AD797as signalamplification. It uses STM32as MCU. The data processing algorithm and the model of differential absorption method are established. It can exclude the interference of externalenvironment. In this way, the detection effect can be improved.This paper has completed the design of detection system in low concentration of CO.It includes the design in optical, absorption chamber, signal acquisition and processingcircuit. Through the CO analysis model, it can monitor the low concentration CO gas in theair. The detection system has good real-time, accuracy and adaptability. It can also beapplied to other gases. So system has a good development and application prospects. Itprovided a batter theoretical reference and practical value for the field of environmental,monitoring, disaster prevention and mitigation. |
