开放型TDLAS-WMS技术CO_(2)痕量气体检测  

Measurement of Trace CO_(2) Concentration with Open-path TDLAS-WMS Technology

作　　者：赵成龙 黄丹飞[1] 刘智颖[1] 王昱琪 钟艾琦 张耹铭 孟凡宏 ZHAO Chenglong;HUANG Danfei;LIU Zhiying;WANG Yuqi;ZHONG Aiqi;ZHANG Qinming;MENG Fanhong(Changchun University of Science and Technology,School of Opto-Eelectronic Engineering,Changchun 130022,China)

机构地区：[1]长春理工大学光电工程学院,长春130022

出　　处：《光子学报》2022年第2期323-332,共10页Acta Photonica Sinica

基　　金：国家自然科学基金(No.61893096014)。

摘　　要：采用窄线宽、边模抑制高的DFB激光器研制一套开放型TDLAS波长调制技术气体检测装置。选取2004 nm处CO_(2)分子吸收峰作为吸收谱线,采用锁相放大器进行调制、解调后的二次谐波信号幅值检测气体浓度大小。设计基于开放环境中的Herriott型气体吸收池,使用ZEMAX非序列模式进行吸收池仿真,光线追迹后理论光程可达到1350 mm,实际光程由50 mm增加到300 mm,检测浓度下限数值由原先的1300 ppmv降低到214.28 ppmv,有效提高了系统的检测下限能力。配置不同浓度的CO_(2)气体检测,得到二次谐波信号幅值与浓度之间呈现很好的线性关系,其拟合系数为0.99839,可通过拟合直线方程计算得出待测气体的浓度。配置300 ppmv的CO_(2)进行Allan方差分析,积分时间到101.6 s时,Allan方差处于平稳状态,检测系统的灵敏度为1.512×10^(-5)。检测结果表明检测装置实现了对CO_(2)气体浓度准确测量。该装置可进行结核分枝杆菌呼吸产生的CO_(2)气体浓度进行检测,为肺结核病诊断提供依据。The DFB laser with narrow linewidth and high side-mode suppression is used to develop a set of open TDLAS-WMS CO_(2) gas detection device.At present,most of the CO_(2) absorption spectra at1570 nm are still used.According to the query in HITRAN database,CO_(2) absorption intensity at 2004 nm is stronger than that at 1570 nm.The CO_(2) molecular absorption peak at 2004 nm was selected as the absorption spectrum.Based on the detection principle of TDLAS technology,the Lorentz linear gas absorption spectrum was obtained through MATLAB simulation.Gas absorption spectrum wavelength modulation technique to obtain a second harmonic and harmonic signals,because even order harmonic signal strength down line center and the largest signal strength weakened along with the increase of harmonic times fast,odd harmonic signals in the spectrum of gas absorption peak amplitude getting minimum value is zero,so generally choose accidentally time,low harmonic detection of gas concentration,Odd harmonic is used to stabilize the frequency of the laser.In the experiment,the amplitude of the second harmonic signal after modulation and demodulation by a phase-locked amplifier is used to detect the gas concentration.The Herriott type gas absorption tank was designed based on the open environment because of the limitation of the widely used Herriott absorption tank to the detection method of microbial exhaled gas.Compared with the closed absorption cell,the open absorption cell reduces the detection time and operation complexity.The optical structure of absorption cell was simulated by using ZEMAX non-sequence mode.After ray tracing,the theoretical optical path could reach 1350 mm,the actual optical path increased from50 mm to 300 mm,and the lower limit value of detection concentration was reduced from 1300 ppmv to214.28 ppmv,which effectively improved the detection lower limit ability of the system.The experimental device uses STM32F103VET6 master controller,which controls the DDS chip AD9834 to generate high frequency sine wave signal an

关 键 词：TDLAS-WMS 谐波信号 痕量气体检测 DFB激光器 CO_(2) 

分 类 号：TN271.5[电子电信—物理电子学]