基于腔增强吸收光谱技术的气体探测研究

以近红外可调谐半导体激光器为光源,以反射率为99.7%左右的平凹镜组成的稳定光学谐振腔作吸收池,构建起一套腔增强吸收光谱（CEAS）系统;以二氧化碳气体（CO2）、一氧化碳气体（CO）、甲烷气体（CH4）以及一氧化碳和二氧化碳的混合气体为样品,利用分子在近红外波段的特征吸收,研究了在近红外波段用CEAS技术探测CO、CO2、CH4等气体的可行性;同时也对基于可调谐半导体激光器的CEAS系统中激光器的波长定标、谐振腔（吸收池）的透射特征等做了研究,获得了CO、CO2、CH4以及CO和CO2混合气体的特征吸收谱,最后对CEAS技术在定量测量方面的能力做了研究.研究结果表明,CEAS技术的探测灵敏度可达5.687×10^-7cm^-1,是一种装置简单、操作方便、灵敏度高、稳定性好的定量吸收光谱技术.

The study of gas detection based on the cavity enhanced absorption spectroscopy technology

The cavity enhanced absorption spectroscopy system（CEAS） is constructed with the near-infrared tunable DFB diode laser used as the light source and an optical cavity, which is composed by two plane-concave mirrors with the reflection of about 99. 7%, used as the absorption cell. In the experiment, carbon dioxide（ CO2 ）, carbon monoxide（CO） ,methane（CH4） and the mixture of CO ＆ CO2 are employed as the samples. The feasibility is studied of detecting CO, CO2, CH4, and CO ＆ CO2 mixture in the near-infrared band by means of CEAS technology, which is based on the molecular characteristics absorption in the near-infrared band. Meanwhile, the diode laser wavelength calibration and the characteristics of optical cavity transmission are also researched, thus obtaining the characteristic absorption spectrum of CO, CO2 , CH4, and CO ＆ CO2 gas mixture. At the end, the quantitative measurement capacity of CEAS technology is also studied. The results indicate that this technology has the sensitivity as high as 5.687×10^-7cm^-1 ,and so is a quantitative absorption spectrum technology with simple device, convenient operation, high sensitivity and good stability.