This is OCA20 made by American Dataphysics Corporation. The video-supported contact angle measuring instrument OCA 20 is the top instrument from the comprehensive modular "OCA construction kit". It is characterized by a multitude of technical detail solutions in mechanical, optical and electronical components and by its powerful software modules. It was developed for the measurement of the static and dynamic contact angles according to the "Sessile & Captive Drop Method" and the "Pendant Drop Method", to determine the surface free energy of solid bodies and its components as well as for determining the surface and interface tension of liquids from the drop or lamella contour. Since the detection of the precise temperature is important for all thermodynamic values, it has already integrated temperature measurement in the range from -10 to +400 °C. In a word, this device is very useful for our study.