Method and apparatus for we shall now describe the presence or absence of a coating on a substrate

摘要

The invention relates to a process and apparatus for we shall now describe the presence or absence of a coating 12 on a substrate 10. The substrate is placed with its face carrying the coating in contact with a guide for application 18 has a enlightened end by a light beam 28, according to the principle of the internal reflection, it controls, for example, by means of photodetectors 34, 34, the application diffusee by the surface of the coating, the absence of such an application diffusee indicating the absence of the coating.