Based on the CH4 absorption spectrum, a novel kind of transmission-type optical fiber CH4 sensor with the low-cost illuminant of LED is presented in this paper. Two same types of LED illuminant are selected as difference absorption signals, and alternative chopping is automatically realized by illuminant driver. The approaches of increasing the coefficient of photo-absorption by CH4 and the experiment results of CH4 concentration are also shown.%根据甲烷气体的吸收光谱，研究了一种用低廉的LED作光源的新型透射式光纤甲烷气体传感器.选择两同型号LED光源作为差分吸收信号.光源驱动器自动实行交替斩波.讨论了提高甲烷对光吸收系数的方法及途径，给出了甲烷气体浓度的测量结果.
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