基于TDLAS-WMS的近红外痕量CH4气体传感器

摘要

In order to monitor CH4 gas in real-time under coal-mine,design,research and fabricate trace CH4 sensor using distributed feedback(DFB)laser with centre wavelength of 1. 65μm,which is based on tunable diode laser absorption spectroscopy(TDLAS)and wavelength modulation spectroscopy(WMS)detecting technology. The spectrum of DFB laser can scan CH4 transition absorption spectrum through adjusting working temperature of DFB laser utilizing independent design DFB laser temperature controller. In order to decrease the 1/f noise,WMS detection technique is utilized to transfer the detection signal into high frequency region. The trace CH4 sensor is applied to extract the second harmonic signal within the detection range of( 0~106 )× 10-6 . Detection results show that the relative detection error is less than 7% within the detection range of(0~106 )×10-6 and the lowest detection is 11 × 10 -6 . Meanwhile,the researchers can detect other gases through replacing lasers with different wavelength.%为了对煤矿CH4气体进行实时监测，基于混合可调谐二极管激光吸收光谱（ TDLAS）与波长调制光谱（WMS）的检测技术，采用中心波长为1.65μm的分布反馈（DFB）激光器，设计并研制出痕量CH4气体传感器。利用自主设计的DFB激光器温度控制器，通过调节激光器工作温度，进而使其发光光谱扫描CH4气体的吸收跃迁谱线。同时利用WMS检测技术将待测信号频率移至高频区，减小1/f噪声。利用该痕量CH4气体传感器，在被测气体体积分数为（0～106）×10-6的范围内，对二次谐波信号进行了提取。测试结果显示：在（0～106）×10-6范围内相对测量误差小于7%，检测下限为11×10-6。同时，研究人员可以通过更换其他波长的激光器，实现对其他气体的检测。