基于红外光谱吸收的煤矿瓦斯光纤传感网络

基于气体在其特征吸收波长下光的吸收随浓度变化的原理，通过对甲烷气体红外吸收光谱的分析，设计了一套检测甲烷气体浓度的多点光纤传感网络。该系统采用分布反馈式半导体激光器(DFB LD)作为光源，高灵敏度、低噪声的InGaAs PIN作为光电探测器，结合空分复用技术复用了16个甲烷气体传感器，采用滤波、前置放大等电路对微弱信号进行处理，经PCI数据采集卡采集各路信号后，再用软件编写程序对采集信号进行快速傅里叶变换等分析。研究表明，该网络各传感器的灵敏度均达到200 ppm(μｇ·mL-1)，长时间的精确度和稳定性均可满足实际要求，单个传感器的响应时间小于2 s，系统巡检一周的时间小于32 s。通过理论分析得出，该系统各传感器可放置于离地面20公里以上的矿井中，且该系统可在多场合进行多点的实时检测。

Methane Optic Fiber Sensor Network Based on Infrared Spectrum Absorption in Coal Mine

Through analyzing the infrared absorption spectrum of methane, a multi-point optic fiber sensor network was designed based on the principle of light absorbing capability of gas which varies with gas concentration at its characteristic wavelength. A distributed feedback laser diode (DFB LD) was used as the light source and an InGaAs PIN as the photodetector which features high sensitivity and low noise. Sixteen methane sensors were multiplexed in this system with space division multiple access technology (SDMAT), and the faint signals were processed by the filtering and amplifying circuit. All signals were gathered by the PCI data acquisition card, and finally, the signals were analyzed by the fast Fourier transform with software. The results showed that the sensitivity of every sensor reached 200 ppm(μg·mL-1), long-time accuracy and stability of all sensors could meet the practical demands, the response time of each sensor was less than 2 seconds and the detecting period was less than 32 seconds. By theoretical analysis, all sensors could be put in the mine at least 20 km from the ground, and the instruments could be applied to multi-point measurement at real-time in multiple occasions.