实验设计了一种基于可调谐二极管激光吸收光谱技术的甲烷传感系统，主要针对宽温度范围、全浓度、高精度的实时检测仪器进行研究。优选1653.7 nm 窄线宽分布反馈式激光器作为光源，采用多次反射气室，结合波长调谐和全数字锁相放大器的二次谐波信号检测技术，通过最小二乘法拟合不同温度和不同浓度下的二次谐波测量数据，对检测系统进行背景扣除和温度补偿，高精度地反演出甲烷气体的浓度。实验结果表明，系统在浓度为0~1%时的检测误差小于±0.02%，1%~100%时检测误差小于真值的±2%，响应时间小于10 s。长时间的稳定性测试和高低温实验证实该系统可靠性高，能够稳定工作在宽温度范围内(0 ℃~40 ℃)。该系统满足煤矿检测标准的要求，为防治瓦斯突出灾害提供了保障。

A methane gas sensor system based on tunable diode laser absorption spectroscopy is designed, mainly aiming at wide temperature range, full concentration, high precision of real-time testing instruments. The feature of high sensitivity is accomplished by choosing a 1653.7 nm narrow-linewidth distributed-feedback laser source, adopting the multiple reflection chambers and combining wavelength tuning with full digital lock-in amplifier. Using the least squares method, the second harmonic signal data under different temperature and concentrations are fitted. The detection accuracy is improved by taking background subtraction and temperature compensation methods. Experimentally, the low-power on-line system can test the methane gas in full-scope concentration range. It has response time of less than 10 s, and its testing error is lower than ±0.02% under the concentration of 0~1%, and lower than ±2% of actual value under the concentration of 1%~100%. Through the long time stability test and high-low temperature test, high reliability in a wide temperature range (0 ℃~40 ℃) of the system is verified, and the system meets the coal mine test standards and provides guarantee for prevention and control of methane gas outburst hazards.