中文摘要：

采用可调谐激光吸收光谱（TDLAs）技术和光分路技术，实现了多通道光纤可燃气体监测系统的研制。系统中，监测仪部分采用分离式设计，无源传感探头和有源仪表之间通过光纤连接，含有浓度信息的光信号通过光纤传输到仪表进行处理。传感探头仅由气室和光纤组成，不带有任何电路，可以保证探头的本质安全性和抗电磁干扰能力。设计了乘法解调电路，以解决光纤传输产生的相位延时，而导致测量结果偏差的问题。测试结果表明，本文系统能够实现现场非电、远程、长期在线和分布式气体浓度监测预警预报，且检测结果不受光纤长度变化的影响，在工业标准的100最低爆炸极限（LEL）测量范围内能够正确检测CH4气体浓度值，检测灵敏度为0．1LEL．

英文摘要：

This paper realizes the four-channel optical fiber combustible gas monitoring system by using the tunable diode laser absorption spectroscopy （TDLAS） and light splitting technology. The monitoring of the system is the separation type. The passive sensing probe and active instrument are connected by the optical fiber. The light signal containing concentration information transfers to the instruments to be processed through the optical fiber. The sensing probe which is only composed of the gas chamber and optical component without any circuit can guarantee the intrinsic safety and the anti-interference ability of the probe. The system can realize the warning forecast of the remote, long-term online distributed gas concentration. The paper also designs a phase-lock multiplication demodulating circuit, which can analyze the weak signal and solve the phase delay caused by the fiber transmission and find a solution to the de- viation of the results. The monitor system emplaces 71 optical fiber methane sensing probes in a large oil depot reservoir area. The long-term experiment results show that the measurement results of the system are not influenced by the length of the optical fiber, and the system can get a correct detection of gas concentration value in the 0--5% （0--100 LEL） measuring range.