基于激光光谱法的反射表面上膜厚测量方法研究

Liquid film is usually formed on opaque (such as metal) surfaces in various industrial processes. Hence, measurement of liquid film thickness with high accuracy on opaque surfaces is very important for the relevant processes. In this paper, a novel on-line measurement method was developed to measure the film thickness on reflecting surfaces based on diode laser absorption spectroscopy (DLAS). An inversion model of film thickness on reflecting surfaces was established. An evaporating film deposited on a silver-coated mirror at room temperature was investigated, and shadowgraph imaging was employed to validate the measurement accuracy of this method. The results indicated that the variation trend of the film thickness was in good agreement with DLAS technique and shadowgragh imaging, and the deviation was 1.3% between these two techniques before the film was drastically contracted.