光腔衰荡光谱技术用于OH浓度测量的误差分析

Uncertainty analysis of OH concentration measurement by optical cavity ring down spectroscopy

光腔衰荡光谱技术(Cavity Ring Down Spectroscopy,CRDS)是一种高灵敏度的吸收光谱测量技术,在燃烧场激光光谱诊断领域里是一种十分重要的燃烧产物定量测量手段。文中研究了光腔衰荡光谱技术用于燃烧产物定量测量的原理,搭建了脉冲型光腔衰荡光谱技术实验系统,选取OHA2Σ+-X2Π(0,0)电子跃迁带的P1(2)吸收线谱,在常压条件下对平面火焰的OH浓度进行了定量测量,并对激光器线宽及线型、激光器的频率稳定性、火焰温度、光腔参数等因素对测量误差的影响进行了分析讨论。误差分析给出了光腔衰荡光谱技术的几个关键注意事项,可为光腔衰荡光谱技术的应用提供指南。

Cavity ring down spectroscopy （CRDS） is an absorption spectroscopy technique with high sensitivity, which is a very important quantitative concentration measurement approach in combustion spectral diagnosis. The principle analysis of CRDS was presented to apply to absolute concentrations of intermediate species in flames, and then an experimental setup of pulsed CRDS was established based on this principle. The absolute OH concentration was measured by using absorption on the P1（2） rotational line in the A2X-ZII （0,0） band of OH on a plat flame at atmospheric pressure. Influence of several major factors on the measurement uncertainty was analyzed, such as laser line shape and linewidth, frequency stability of the laser, flame temperature, and cavity parameters. This uncertainty analysis provides several guidelines to improve the measurement accuracy of CRDS.