Dissertation
Dissertation > Industrial Technology > Automation technology,computer technology > Automation technology and equipment > Automation components,parts > Transmitter ( converter),the sensor > Chemical sensors

Research of Key Technologies of Optical Fiber Methane Gas Sensor with Spectrum Absorption

Author WangChun
Tutor CaoJiaNian
School Harbin Engineering University
Course Communication and Information System
Keywords Methane Spectral absorption Harmonic Detection Fiber Optic Sensors
CLC TP212.2
Type Master's thesis
Year 2009
Downloads 43
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Since the 1980s , based on the spectral absorption of the gas concentration detection technology has been a great development. Gas absorption spectrum characteristics , detection of gas concentrations , it has become an important research direction of the optical fiber sensor . Traditional chemical formula of methane gas sensors in use exist easily affected by moisture , easy to \Gas characteristic absorption lines , subjects choose the methane gas in the of 1653.72m for absorption spectrum , the analysis of the absorption spectra of methane gas , commonly used wavelength modulation to achieve the gas concentrations harmonic detection programs , clearly the detection method of the spectral absorption-type methane concentration . Each harmonic characteristics of the detection method involves relations with each other , the basic principles of harmonic detection signal-to-noise ratio under conditions of weak harmonic signal detection theory, the light source fluctuations on the test results and other key technologies . At the same time , from the point of view of practical engineering applications , proposed the existence of a solution to the problem of the key technologies as well as the actual circuit structure . Test using the AD630 balanced modulator to achieve lock-in amplification in order to achieve the detection of the weak harmonic signal , to improve the SNR of the harmonic signal . And using the second harmonic of the first harmonic ratio analysis to eliminate the impact caused by the light source fluctuations . Harmonic Detection of the methane gas is given the overall program, a clear spectral absorption optical fiber methane gas sensor with the overall structure of the test system , wherein the main part of the signal generating unit and the harmonic extraction and digital processing section do the appropriate test , verified the feasibility of the solution . Through the study of the spectral absorption optical fiber methane gas sensor system key technologies , laid the foundation for further advancing the methane gas fiber optic sensors practical .

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