Optical contact angle measurement of a liquid and solid and/or drop contour analysis of a liquid The optical contact angle measuring and contour analysis systems devices are used for the analysis of interfacial parameters and phenomena. The optical analysis of drops that hang from a dosing needle or are placed on a solid surface facilitates the determination of different surface and interfacial parameters. The contact angle that a liquid drop establishes on a solid surface characterizes the solid’s wetting behaviour with said liquid. Having measured the contact angles of multiple test liquids the surface energy of the solid can be determined and the latter can be used to calculate the work of adhesion for different liquids. The measurement of the contact angles aids on the development of surface coatings, composite materials, paints and varnishes or cleaning agents. Serves to obtain information on the surface properties of a solid among other hydrophobicity / hydrophilicity. It is useful in all situations where solids and liquids meet and advantage is to be gained by the control of wetting and adhesion properties.