根据煤矿安全生产监控系统对测量甲烷浓度全量程高准确度的需要, 基于可调谐半导体激光吸收光谱技术, 设计了一种全量程一体化激光甲烷传感器.采用1 653.72 nm 分布式反馈半导体激光器作为系统光源, 单板电路实现激光器驱动、温度控制、信号调制与解调、浓度反演.为兼顾高测量准确度和大动态测量范围, 系统在低浓度时利用波长调制技术进行甲烷浓度在线检测; 当气体浓度大于阈值时, 自动切换到直接吸收检测技术.实验结果表明, 该传感器在浓度范围为0～5%内误差小于±0.06%, 在浓度范围为5～100%内误差小于真值的±6%, 响应时间约为15 s, 满足矿井实际测量需要.

According to the needs of full range and high precision measurements of methane concentration in coal mine safety production monitoring system, a full-scale integrated laser methane sensor was designed based on a Tunable Diode Laser Absorption Spectroscopy (TDLAS). A 1 653.72 nm Distributed Feedback Laser(DFB) semiconductor laser was employed as the system light source. Laser driving, temperature controlling, signal modulation and demodulation, and concentration calculation were realized by a single board circuit. To meet a high measurement precision and a large dynamic measurement range simultaneously, the wavelength modulation technique was used to detect the methane at a low concentration. When the gas concentration is higher than the threshold set in the system, the direct absorption detection technique was switched to automatically. Experimental results show that, the measurement error is less than ±0.06% in the range of 0～5% and less than ±6% of the actual value in the range of 5～100%, and the response time is less than 15 s, which meets the requirements of the mine measurement in practice.