Research On Optic Fiber Methane Sensor

Methane is a main component of marsh gas, and it is very important to detect methane's consistency reliably accurately and rapidly for the safe production in mine and environment protection. With high sensitivity, wide frequency response, suitable for bad environment, optic fiber gas sensor is drawing more and more researchers' attention.Based on the mechanism of absorption spectrometer, an optic fiber gas sensor for methane was designed, and light source, the detector part, the gas absorption cell and sensor were realized in this dissertation. The 1665nm DFB LD servered firstly as narrow band light source for detecting, and a phase locked amplifier is used to detect the signal. The specific absorption characteristic of methane in 1665nm is studied by the experiment system, and the absorption coefficient of methane was measured in high consistency in 1665nm. The function of the system was analysed by diffuseness experiment and stability experiment. It shows that the minimum dectectable gas concentration can reach to 1.6%, the sensitiy and the differentiation reach to 0.0075uW/ppm and 66ppm respectively. The system is of good stability and repeatability.