报导了一个利用LED作光源探测甲烷浓度的差分探测系统,分析了系统中各光学元件的作用,给出甲烷浓度的计算方法及实验结果.选用甲烷在1.65 μm附近2ν3谱带中的R支作为探测对象.利用法布里-珀罗标准具的透过率曲线与甲烷吸收线相互匹配的方法滤掉无用光,并通过压电陶瓷改变标准具的腔长,从而实现了差分吸收探测,进一步提高了测量灵敏度,取得了较好的结果.

In this paper, a differential measurement system of methane concentration by using LED as the light source is reported. The functions of each optical element in the system are carefully analyzed, and the calculation method and the experimental results of methane concentration are given. The R branch in 2ν_3 spectral band are selected as the working spectral lines. A Fabry-Perot interferometer is used,and the transmission curve of the interferometer matches the absorption peaks of the methane at the working spectral lines.So that the useless light from the light source can be filtered out. The cavity length F-P interferometer is modulated by PZT, and the differential absorption measurement is realized. In this way, the measurement sensitivity is enhanced and a good result has been achieved.