采用长光程差分吸收光谱技术(LP-DOAS)的中红外痕量一氧化碳检测仪  

Development of Mid-Infrared Trace-CO Detector with Long-Path Differential Optical Absorption Spectroscopy(LP-DOAS)

作　　者：吕默[1] 王一丁[1] 陈晨[2] LU Mo WANG Yi-ding CHEN Chen(State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Chang- chun 130012, China Key Laboratory of Geo-Exploration Instruments, Ministry of Education, College of Instrumentation ＆ Electrical Engineering, Jilin University, Changchun 130061, China)

机构地区：[1]吉林大学集成光电子学国家重点联合实验室电子科学与工程学院,吉林长春130012 [2]吉林大学地球信息探测仪器教育部重点实验室仪器科学与电气工程学院,吉林长春130061

出　　处：《光谱学与光谱分析》2017年第7期2278-2282,共5页Spectroscopy and Spectral Analysis

基　　金：国家高技术研究发展计划(863)计划项目(2013BAK06B00)资助

摘　　要：一氧化碳作为一种危险的开采排放气体,在复杂的井下环境中极易累积,对矿工生命安全造成严重威胁。介绍了一种紧凑型一氧化碳检测仪,该仪器采用激发波长为4.65μm的量子级联激光器作为光源,配合中红外碲镉汞光电探测器与光程长度12m的紧凑型多次反射气室,实现了对痕量一氧化碳气体的检测。自主设计的新型高速光电信号采集系统解决了应用商业示波器造成的信号链阻抗失配的问题。这一新系统的采样带宽为400MHz,采样频率1GSPS,垂直分辨率达到12bit,有效的提高了检测仪的灵敏度与集成度。该仪器采用长光程差分吸收光谱法,通过比较实测光谱与进行Voigt展宽的理论光谱之间的残差得出此检测仪的检测下限为108×10-9。检测仪的测量误差有非平稳,慢时变的特点。根据这一特点我们采用阿伦方差对气体检测仪检测灵敏度进行了估计,经过约40s方差曲线达到极小值,此时阿伦方差值为61×10-9。在2h的稳定性测试中,检测仪稳定度达到2.1×10-3,在长达12h的稳定性测试中,检测仪的稳定度依然可以达到1.7×10-2。此仪器具有较高的灵活性,通过更换不同激射波长的激光器可以实现对多种气体的痕量检测。Carbon monoxide,as a kind of dangerous mine gas,can easily accumulate in a complex mine environment poses a serious threat to the safety of miners.This paper presents a compact carbon monoxide detector.This instrument have a mid-infrared quantum cascade laser operating at 4.65μm as light source,with mercury cadmium telluride（HgCdTe）detector and 12 mcompact absorption path to obtain trace-CO diagnostics.Self-designed high-speed photoelectric signal acquisition system solved the signal chain impedance mismatch problem which caused by commercial oscilloscope.This new acquisition system realized 1GSPS sampling rate and vertical resolution of 12 bit at 400 MHz sampling bandwidth which improved the detector＇s sensitivity and integration effectively.This instrument use long path differential optical absorption spectroscopy（LP-DOAS）theory.The detection limit of the instrument which gives as 108×10-9 is obtained by comparing the residual between the measured spectrum and calculated theoretical spectrum with Voigt broadening.Detector＇s measurement error has non-stationary,slowly time-varying characteristics.According to this feature we use Allan deviation to estimated detector＇s sensitivity,after about 40 seconds the deviation curve reached the minimum.The Allan deviation value is 61×10-9.In two-hour tests,the stability of the detector is2.1×10-3,for up to 12 hours of stability tests,the detector＇s stability can still reach 1.7×10-2.This instrument has high flexibility,through the replacement of different laser with different lasing wavelength;it can be achieved on a variety of trace gas detection.

关 键 词：量子级联激光器 痕量气体检测 光电信号采集系统 长光程差分吸收光谱 残差分析 阿伦方差 

分 类 号：O657.3[理学—分析化学]