Process for detecting layers on metallic surfaces in printing machines

摘要

The invention relates to a method and device for detecting ink or lacquer films on metallic surfaces inside printing machines. In particular, to irradiate the surface with light and sensing of the intensity of the reflected light to detect whether an ink film or lacquer film on a roller has been completely removed by applying a metering element or doctor-blade element. This is achieved according to the invention by the irradiation of the metallic surface or of the film located thereon, and the reception of the light reflected from the surface or the film located thereon is performed at the Brewster angle with respect to the surface normal, the Brewster angle being defined by the refractive index of the material of the film to be determined and that liner polarization of the light is performed at least partially in the plane of incidence, at least in one of the two beam paths.