基于中红外中空波导光纤的呼吸气体CO2实时测量  

Real-Time Exhaled CO2 Gas Measurement Using a Mid-Infrared Hollow Waveguide Fiber

作　　者：马帅 吴涛[1] 孙城林 周韬 何兴道[1] Shuai Ma;Tao Wu;Chenglin Sun;Tao Zhou;Xingdao He(Key Laboratory of Nondestructive Test(Ministry of Education),Nanchang Hangkong University,Nanchang,Jiangxi 330063,China)

机构地区：[1]南昌航空大学无损检测教育部重点实验室,江西南昌330063

出　　处：《光学学报》2020年第11期209-215,共7页Acta Optica Sinica

基　　金：江西省科技厅重点研发计划(20192BBH80019)。

摘　　要：提出一种基于中红外中空波导光纤的呼吸气体CO2测量系统,该系统使用中心波长为2.73μm的分布式反馈(DFB)激光器结合1 m长的中空波导光纤,采用免标定波长调制光谱技术(CF-WMS)对呼吸气体CO2进行实时测量。采用CF-WMS技术得到的CO2气体浓度与配制所得的标准气体浓度之间的线性度为0.9999,在体积分数为0%~6%的范围内,测量结果与标准气体体积分数值之间的最大绝对误差为0.01%。由CF-WMS技术反演的CO2体积分数精度为1.01×10^-5,在最佳积分时间26.00 s时,CO2气体的探测极限为1.3×10^-6。基于CF-WMS技术与传统的标定式波长调制技术(WMS)测量CO2气体体积分数的精度和灵敏度,并将两者进行比较,结果发现CF-WMS技术相对于WMS技术,测量精度提高了一倍,CF-WMS技术测量灵敏度为WMS技术测量灵敏度的1.4倍。对呼吸气体CO2实时测量时,采用CF-WMS技术测量的背景CO2体积分数基本稳定在3.8×10^-4左右,呼吸末CO2体积分数稳定在5.7%附近。In this study,we propose an exhaled CO2 gas measurement system based on a mid-infrared hollow waveguide fiber.A distributed-feedback(DFB)laser with a central wavelength of 2.73μm and a 1-m hollow waveguide fiber were used in the proposed system.The exhaled CO2 gas was measured in real time via calibration-free wavelength modulation spectroscopy(CF-WMS).The linearity with respect to the CO2 concentration obtained via CF-WMS and the prepared standard CO2 gas concentration is 0.9999.Further,when the volume fraction is 0%--6%,the maximum absolute error between the measurement results and the volume fractions of the standard gas is 0.01%.The precision of the CO2 volume fraction retrieved via CF-WMS is 1.01×10^-5,and the CO2 gas detection limit is 1.3×10^-6 at an optimal integration time of 26.00 s.Subsequently,the measurement accuracy and measurement sensitivity of CF-WMS and the traditional calibrated wavelength modulation spectroscopy(WMS)were compared.The obtained results demonstrate that the measurement accuracy and measurement sensitivity of CF-WMS are twice and 1.4 times those of WMS,respectively.The background CO2 volume fraction obtained via CF-WMS is observed to remain stable at approximately 3.8×10^-4 during real-time measurement of the exhaled CO2 gas;further,the CO2 volume fraction observed immediately after exhalation remains stable at approximately 5.7%.

关 键 词：光谱学 激光吸收光谱 波长调制技术 呼吸气体分析 二氧化碳 

分 类 号：O436[机械工程—光学工程]