基于多模激光关联光谱的甲烷气体检测技术  

Sensitive detection of CH_4 based on tunable multi-mode diode laser correlation spectroscopy

作　　者：高光珍 蔡廷栋 张婷 张刚 GAO Guang-zhen;CAI Ting-dong;ZHANG Ting;ZHANG Gang(College of Physics and Electronic Engineering,Jiangsu Normal University,Xuzhou 221116,China)

机构地区：[1]江苏师范大学物理与电子工程学院,江苏徐州221116

出　　处：《光电子．激光》2019年第2期140-145,共6页Journal of Optoelectronics·Laser

基　　金：国家自然科学基金(61805110;61875079;61475068;11104237);徐州市科技计划项目(KC16SG257;KC16H0231)资助项目

摘　　要：为提高多模激光吸收光谱的灵敏度,将多模二极管激光关联光谱、长程吸收技术和波长调制光谱结合,建立了一套具有高检测灵敏度和高稳定性的气体检测系统。采用1 675 nm多模激光器作为光源,以光程为100 m的离散镜片型多通池作为气体吸收池,利用甲烷的2ν_3泛频带吸收谱线,通过计算待测气体和参考气体的二次谐波信号峰值之间的关系,实现了对CH_4气体的测量。实验在室温和20.265 kPa(即0.2个标准大气压)条件下进行,CH_4浓度范围为1.00×10^(-5)-1.10×10^(-2)。实验结果表明,CH_4浓度测量值与真实值之间具有良好的线性关系,其线性度为0.997,系统的测量准确度为3.50%,对浓度为2.60×10^(-6)的气体样品在30 min内的连续测量表明系统稳定度优于2.53%。本方法具有操作简单、稳定性好、灵敏度高和环境适应性强等优点,在工业过程控制和环境监测中具有广阔的应用前景。A gas molecular spectroscopy measuring device with high detection sensitivity and high stability is built by using a multi-mode diode laser near 1 675 nm as the light source,which can probe the CH4 transitions in the 2ν3 overtone band.In order to improve the detection limit of the system,a discrete lens-type multi-pass call with path length of 100 m is employed as the measurement absorption cell.The multi-mode diode laser correlation,wavelength modulation technology and long-path absorption spectroscopy are combined to improve the sensitivity of the system.The CH4 concentrations are derived from the relationship between the normalized WMS-2f signal peak heights of the measurement and reference signals which are selected based on high signal to noise ratio and correlation coefficient.The experiments are carried out at room temperature and 20.265 kPa,and the CH4 concentration range is 1.00×10-5-1.10×10-2.The calculation results show that there is a highly linear relationship between the measured and actual CH4 concentrations,the linearity is 0.997 over the whole tested range,and the standard deviation is 3.50%.The stability of 2.53% is achieved for a sample with CH4 concentration of 2.60×10-4,using 30 successive measurements with each measurement time taking ~10 s during 30 min.The design can meet the needs of methane online monitoring.The system has higher reliability and stability,and is immune to the variation of the environment.

关 键 词：可调谐多模二极管激光器 关联光谱 长程吸收 甲烷浓度 

分 类 号：O657.3[理学—分析化学]