基于微型多次反射腔的TDLAS二氧化碳测量系统  

Study on TDLAS System with a Miniature Multi-Pass Cavity for CO_2 Measurements

作　　者：李萌[1] 郭金家[1] 叶旺全 李楠[1] 张志浩 郑荣儿[1] LI Meng;GUO Jin-jia;YE Wang-quan;LI Nan;ZHANG Zhi-hao;ZHENG Rong-er(Optics and Optoelectronics Laboratory,Ocean University of China,Qingdao　266100,China)

机构地区：[1]中国海洋大学光学光电子实验室,山东青岛266100

出　　处：《光谱学与光谱分析》2018年第3期697-701,共5页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金重大科研仪器研制项目(41527901);中央高校基本科研业务费项目(201562010)资助

摘　　要：海气界面CO_2测量对于海洋科学研究具有重要意义,在目前的海洋CO_2测量仪器中,基于可调谐二极管激光吸收光谱技术(TDLAS)的设备因灵敏度高、环境适应性强等特点受到关注。TDLAS系统的体积和灵敏度通常受限于多次反射腔的大小和光程。针对海洋CO_2脱气量小且灵敏度高的测量需求,自主设计了一套微型多次反射腔,用于TDLAS系统的CO_2测量。该微型多次反射腔采用两片口径为25.4mm、焦距为50mm的球面反射镜,以38mm的腔长实现了253次反射,获得了约10m的光程,封装后的样品池体积仅有90mL。基于该微型多次反射腔搭建了一套直接吸收TDLAS的CO_2气体浓度测量系统,通过标准气体对该系统进行了测试,检测限约为26×10^(-6),不同浓度气体线性相关度R^2为99.986%。同时还将该系统与LGR公司生产的便携式温室气体分析仪(UGGA)进行了对比测量,结果表明二者在白天CO_2浓度波动较大和夜晚CO_2浓度变化较平稳两种情况下均表现出较好的一致性,R^2大于97%。实验结果证明了系统性能,下一步将优化试验装置并进行现场应用。The measurement of CO 2 at air-sea interface is significant to marine scientific research.There are many commercial instruments can be used for CO 2 measurements in marine environment,among which the instruments based on tunable diodelaser absorption spectroscopy(TDLAS)play an important role due to the advantages of high sensitivity,good environmental adaptability,etc.As a core component of a TDLAS system,the volume and optical path of a multi-pass cavity limit the size and sensitivity of the system.For the application of underwater dissolved CO 2 measurements,due to the samll quantity of degassing gas and highsensitivity,both the small size and long optical path are required for a multi-pass cavity.In this work,a miniature multi-pass cavity was designed for the potential underwater dissolved CO 2 measurements.The miniature multi-passcavity composed of two identical spherical mirrors(D=25.4 mm,f=50 mm)separated at a distance of 38 mm,realized 253 reflection times,providing an effective optical path length of 10 m and an inner volume of 90 mL.Based onthe miniature multi-pass cavity,a direct absorption TDLAS system was developedfor CO 2 measurement.The system was evaluated with a series of different concentrations of CO 2 standard gases.The obtained limit of detection(LOD)was about26×10-6(volume ratio),and the response was good linear with R 2=99.986%over the whole range.A commercial ultraportable greenhouse gas analyzer(UGGA)from Los Gatos Research(LGR)was also used for comparison measurements,and the results showed a consistent trend with R 2 of more than 97%underconditions of both high fluctuation at daytime and low changes at nighttime in laboratory.The experiments testified the performance of the developed TDLAS systemfor CO 2 measurements,which means that the improved system will be used in field experimentsin the near future.

关 键 词：TDLAS(可调谐二极管激光吸收光谱技术) 直接吸收 微型多次反射腔 二氧化碳 

分 类 号：O433.1[机械工程—光学工程]