PROCESS AND DEVICE FOR MEASURING THE THICKNESS OF THIN COLOURED FILMS

摘要

The proposal is for a process and a device for measuring the thickness of coloured films on transparent objects, especially on optical storage media like CDs and CDRs (re-recordable CDs), in which a light beam emitted by a monochromatic light source like laser diodes and LEDs is directed on the object. The wavelength of the light beam is matched to the maximum absorption wavelength of the coloured film. The light beam transmitted by the object is detected by a receiver and the receiver signal is taken to an evaluation device which determines the thickness of the film from the signal.