Greszik Daniel, Yang Huinan, Dreier Thomas, Schulz Christof
Institute for Combustion and Gasdynamics, University of Duisburg-Essen, Duisburg, Germany.
Appl Opt. 2011 Feb 1;50(4):A60-7. doi: 10.1364/AO.50.000A60.
Three different diagnostic techniques are investigated for measurement of the thickness of liquid water films deposited on a transparent quartz plate. The methods are based on laser-induced fluorescence (LIF) from low concentrations of a dissolved tracer substance and spontaneous Raman scattering of liquid water, respectively, both excited with 266 nm of radiation, and diode laser absorption spectroscopy (DLAS) in the near-infrared spectral region. Signal intensities are calibrated using liquid layers of known thickness between 0 and 1000 μm. When applied to evaporating liquid water films, the thickness values derived from the direct DLAS and Raman scattering measurements correlate well with each other as a function of time after the start of data recording, while the LIF signal derived thickness values decrease faster with time due to selective tracer evaporation from the liquid. The simultaneous application of the LIF with a tracer-free detection technique can serve as an in situ reference for quantitative film thickness measurements.
研究了三种不同的诊断技术，用于测量沉积在透明石英板上的液态水膜的厚度。这些方法分别基于低浓度溶解示踪物质的激光诱导荧光（LIF）和液态水的自发拉曼散射，二者均由266nm辐射激发，以及近红外光谱区域的二极管激光吸收光谱（DLAS）。使用厚度在0至1000μm之间的已知厚度的液层对信号强度进行校准。当应用于蒸发的液态水膜时，从直接DLAS和拉曼散射测量得出的厚度值在数据记录开始后的时间函数上彼此相关性良好，而由于示踪剂从液体中选择性蒸发，LIF信号得出的厚度值随时间下降得更快。将LIF与无示踪剂检测技术同时应用可作为定量膜厚度测量的原位参考。
