基于折叠腔的光腔衰荡光谱技术研究  

Cavity Ring-Down Spectroscopy Based on Folded Cavity

作　　者：董贺伟 郭瑞民[1] 崔文超 李东 Dong Hewei;Guo Ruimin;Cui Wenchao;Li Dong(Environmental Measurement Center,National Institute of Metrology,Beijing 100029,China)

机构地区：[1]中国计量科学研究院环境计量中心,北京100029

出　　处：《中国激光》2020年第3期283-289,共7页Chinese Journal of Lasers

基　　金：国家重点研发计划专项(2016YFF0200305)。

摘　　要：为了有效减小光腔衰荡光谱仪中光腔的体积,设计了一种Z型折叠腔结构,其外部尺寸仅为26.4 cm×8.5 cm×4.5 cm,展开的光腔长度为73.8 cm。采用傍轴高斯光束传输方程对实验光路进行仿真,通过调节两个凸透镜的焦距和位置,实现了光腔内激光模式与光腔模式的完美匹配,确保激光在腔内以横基模TEM00模式存在。实验中,采用数字延迟脉冲发生器触发声光调制器,开断激光,并高速采集衰荡信号,验证了所设计的折叠腔在光腔衰荡光谱仪上应用的可行性。对实验数据进行指数拟合,所得最大残差不超过0.004μW,衰荡时间为0.852μs,与理论计算结果相符。所设计的Z型折叠腔结构紧凑,可用于商业化小型光腔衰荡光谱仪。In this paper, to reduce the cavity volume of a cavity ring-down spectrometer(CRDS), we propose designing a Z-folding cavity that has an external dimension of 26.4 cm×8.5 cm×4.5 cm and an expanded length of up to 73.8 cm. In the study, we perform a simulation based on the parallel-Gaussian-beam-transfer-equation to match the laser mode and cavity mode. By adjusting the focal length and position of two convex lenses, we realize mode matching and identify that only the TEM00 mode existes in the cavity. In the experiment, an acousto-optic-modulator is triggered by a digital-delay-generator to switch the laser beam. The feasibility of the Z-folding cavity is verified by the successfully acquiring ring-down signals. By exponentially fitting the experimental data, the ring-down time is determined to be 0.852 μs, which provides a maximum residual of 0.004 μW. The fitted ring-down time is consistent with the theoretical calculation result. The Z-folding cavity designed in this paper is compact and can be used in a commercial CRDS setup.

关 键 词：光谱学 光腔衰荡光谱技术 Z型折叠腔 模式匹配 数据采集 

分 类 号：O433[机械工程—光学工程]