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Design Of Fiber Optic Methane Sensor Detection System Based On Correlation Spectrrscopy And Differential Absorption

Posted on:2011-05-17Degree:MasterType:Thesis
Country:ChinaCandidate:K LiuFull Text:PDF
GTID:2178360302494753Subject:Optics
Abstract/Summary:PDF Full Text Request
Recently, the coal mine accidents in our country, especially gas exploding, happened frequently, which has endangered the miners'lives and the safety of the national properties. Air pollution has seriously affected people's health and life. For the bad gas like methane, carbon monoxide, sulfureted hydrogen, the safe and effective gas detection system is urgently needed. Fiber gas ensing is a high sensitivity developing gas detection technique. Gas concentration easurement is the paper's purpose. Fiber methane gas sensing technique is studied based on the principle of near infrared absorption. The main contents are as follows:Firstly, kinds of the fiber detecting technologies are introduced in the paper, and the actualities and progress directions of the fiber gas sensor are reviewed at home or abroad. The influence factors and key techniques of fiber gas sensor are analyzed. The basic principle of gas absorption measurement is given through the analysis of molecule spectrum theory. The near-infrared absorption spectrum of methane is chosen. And its absorption characteristic is analyzed. Thus, the basic principle of sensor's mathematical model is given.Secondly, the two kinds of simple, single-wavelength differential absorption detection techniques are designed. And a detailed analysis of the two kinds of differential absorption of technology advantages and disadvantages are given.Based on the original advantages and combined with the advantages of correlation spectroscopy, a new differential absorption technique based on the correlation spectrum of methane optical detection technology are proposed.Finally, the characteristics and influences on measurement of light source, gas cell, detector, optical path and electric signal detection system are analyzed. Based on the current experimental device, the characteristics of the source spectrum and the near-infrared absorption of methane are tested. The methane concentration detection, the repeatability and stabilityof the system are studied. The experiments results have proved that the system is feasible.
Keywords/Search Tags:Near-infrared spectrum absorption, Differential absorption technique, The correlation spectrum, Lock in amplifier technique, The active beam path, The reference beam path
PDF Full Text Request
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