Research And Design Of Industrial Gas Laser Sensing Instrument

The environmental pollution has become a big problem that people must pay sufficientattention. In order to keep the Sustainable development of Socioeconomic, we must find solutionto detection, control and management of environmental pollutants. Along with the rapiddevelopment of modern industry in our country. The smoke pollution problem which comes withchemical reactions during industrial production has become more and more critical. Theprotection of air environment is facing a big challenge. How to detect gas concentration which isharmful to environment and people’s health on real-time is very important for environmentalprotection and safety in production.This thesis study and designs The Gas Detection Instrument of laser based on the principleof gas spectral absorption. We take some experiments, to make sure that the system can beapplied in the industrial field. In this thesis, we focus on the detection of CO. We can also detectmany other kinds of gases by making specific settings of the laser wavelength and improvingoptical path without circuit structure changes. This equipment has good application prospects inmany industrial fields that require the measurement of gas concentration.The main work in this thesis include the aspect as follows：(1) The introduction part of the thesis first discussed the source of the topic, and researchbackground. On this basis, we discussed the significance of the research. In addition, theresearch status of the related technologies at home and abroad are introduced, and the researchmethods and procedures.(2) In the second chapter, some analysis were done on the key working technologies and theprinciple of tunable diode laser absorption spectroscopy (TDLAS). We improve detectionsensitivity by means of the wavelength modulation and harmonic detection technology.(3) According to the theoretical analysis, the light path and circuit were designed in chapterⅡI. The central control unit was constructed of NiosⅡ soft-core in FPGA chip. The light-sourcedriver section was composed by current modulation section and temperature modulation section.The feeble signal detection unit was composed by PIN, Preamplifier section, filtering section andPhase-locked-in amplifier section. Data acquisition control unit was also built in FPGA chip.(4) In the fourth Chapter we selected the gas absorption peak of CO first to determine thespecific wavelength DFB LD as the light source. We made the experimental study. Theexperimental results were discussed and analyzed. Include: light source spectra experiments, theprototype performance experiments and industrial field test.