Research of Key Technologies of Optical Fiber Methane Gas Sensor with Spectrum Absorption
|School||Harbin Engineering University|
|Course||Communication and Information System|
|Keywords||Methane Spectral absorption Harmonic Detection Fiber Optic Sensors|
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 .