Laser-based diagnostics for the measurement of liquid water film thickness.
Laser-based diagnostics for the measurement of liquid water film thickness.
复制标题
用于测量液态水膜厚度的激光诊断。
作者：
Daniel Greszik;Huinan Yang;T. Dreier;C. Schulz
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。该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（266 nm辐射激发）以及近红外光谱区的二极管激光吸收光谱（DLAS）。信号强度使用已知厚度在0到1000 μm之间的液体层进行校准。当应用于蒸发的液态水膜时，从直接DLAS和拉曼散射测量得到的厚度值在数据记录开始后作为时间的函数相互关联良好，而LIF信号得到的厚度值随着时间的推移而下降得更快，这是由于液体的选择性示踪剂蒸发。LIF与无示踪检测技术的同时应用可以作为定量薄膜厚度测量的原位参考。
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.