EXPERIMENTAL VISUALIZATION OF PHYSICAL PROCESSES IN tRANSPARENT LIQUID DROPS
The typical examples of experimental results on visualization of evaporating, cooling, crystallization, spreading and mixing of different transparent liquid drops on horizontal glass surface using frustrated total internal reflection of a wide collimated laser beam method are described in the paper. This method is known for a long time and widely used as a convenient tool for measuring the refractive index. To extend the capabilities of the method proposed to use a wide collimated laser beam that allows you to get a picture of the refractive index distribution in a thin boundary layer of the investigated liquid thickness of several hundred nanometers, and not receive local or averaged measurement as usual. In this case, the method allows to see the dynamic of the processes in the droplets boundary layer if there is a change in refractive index of liquid, e.g., due to changes in temperature, concentration or other physical parameters. Furthermore, interference picture are shown which were obtained with created setup. It shows the dynamic change of drops surface shape during evaporation. Also the results of experiments on visualization of spreading of a water drops on a rough surface are described.