中文摘要：

针对传统接触式测量方法探头干扰液膜流动特性导致测量精度难以提高以及传统光学测量方法中光线折射作用限制其应用范围的问题，提出利用平面激光诱导荧光技术测量膜厚的新方法，并对该技术的测试原理、实现方式进行了详细的介绍。通过对沿流向不同位置液膜厚度的实时测量，研究了液膜波动的时序特征及纵向演化规律。结果表明，液膜厚度的概率密度分布的特征差异可作为诊断液膜波动特性的判据。

英文摘要：

The probe of contact measurement interferes with the liquid film flow so that the precision is difficult to be improved .T he application of the traditional optical meth-od is limited because of the light refraction .In order to solve this problem ,a new meth-od was put forward to measure the dynamic film thickness using planar laser-induced fluorescence technique in this paper .The principle and implementation of the technique were introduced in detail .The timing characteristics and vertical evolution of free film were studied based on the real-time measurement along the film flow .The results indi-cate that the probability density distribution of film thickness is different w hich can be used to diagnose the wave characteristics .