Multipoint Remote Methane Measurement System Based on Spectrum Absorption and Reflective TDM

An all-optical methane measurement system was developed. The technologies of spectrum absorption and reflective time domain multiplexing (TDM) were applied. It provides a novel and intrinsically safe solution to achieve the multipoint and remote gas measurement. The information of the concentration and position were obtained at the same time by employing of only a single optic fiber, a single laser source, and a single detector. In order to improve detection sensitivity and accuracy, an optimized gas chamber based on reflective mode was implemented. An experimental system with three measurement points and 4-km optical length was built up. The minimum detection limit of 2% lower explosive level was achieved, and the linear correlation coefficient was 0.999, 0.996, and 0.989 at 0, 2, and 4 km, respectively. The experimental results demonstrate that such a system is suitable for the multipoint and remote gas measurement application.