title: [Research on fiber methane sensing system based on prism gas cell].
abstract: A novel fiber methane detection system was constructed based on integration of prism gas cell and harmonic detection technique. The system can be applied to broad-range concentration detection. Grounded on the Beer-Lambert approximation, the detection of various concentration (0-20%) of methane was completed using subtraction of background and ratio processing method, as the atmosphere surroundings was treated as background. The direct absorption spectra for various concentration were measured using GRIN gas cell, combined with available DFB-LD, and the R5 line of the 2v3 band of methane was selected as absorption peak. The system was tested online during gas mixing process and the linear relation between system indication and concentration variation was validated, while the stability and dynamic response characteristics was confirmed by experiments. The system sensitivity can be adjusted according to the concentration level of various field environments by changing the prism distance using step motor. So that, the system can be applied to various application fields and can be adopted as a monitoring instrument for coalmine tunnel and natural gas pipeline.
authors.affiliation: Measurement Technology and Instrumentation Key Lab of Hebei Province, Yanshan University, Qinhuangdao 066004, China. WUXijun@ysu.edu.cn
authors.forename: Xi-Jun
authors.initials: XJ
authors.lastname: Wu
authors.forename: Yu-Tian
authors.initials: YT
authors.lastname: Wang
authors.forename: Xue-Cai
authors.initials: XC
authors.lastname: Liu
authors.forename: Shu-Jun
authors.initials: SJ
authors.lastname: Li