可调谐激光吸收光谱光纤甲烷传感器研究

Research on a fiber-optical methane sensor based on tunable diode laser absorption spectroscopy

甲烷光谱吸收与气室温度有关,结合甲烷波长1 653.72 nm附近2v3带R(3)支的3条吸收线,分析温度波动对甲烷吸收线的谱线特性及气体浓度反演产生的影响.基于可调谐二极管激光吸收光谱设计了一套带温度信号采集装置的甲烷浓度检测系统,利用校准系数将不同温度下检测得到的二次谐波信号转化为参考温度下的标准信号,反演待测气体浓度.研究表明,气室温度在-20～60℃范围内波动时,系统的测量误差可控制在1%以内,提高了系统的检测精度.

The temperature of the gas cell is an issue in the spectroscopy absorption of methane.Combination of the three absorption lines in the R（3） transitions of the 2v3 band of methane at 1 653.72 nm,the influence of temperature fluctuations on the spectral characteristics,and the concentration retrieval were analyzed.A simple piece of equipment with temperature acquisition devices based on tunable diode laser absorption spectroscopy was developed for measuring the concentration of methane.Using the calibration coefficient,the amplitudes of the second harmonic at varying temperatures were transformed into standard signals at reference temperature to retrieve methane concentration.In the range of-20～60 ℃,the results show that measurement error can be controlled within 1% and detection accuracy is significantly improved.