Patent ID: 9679793
Date: 2017-06-13
CPC Classifications: B05B,B05C,C23C,G01B,H01L

Claim:
1. An optical monitoring system for measurement of layer thicknesses of coatings applied to a substrate during a coating process, the optical monitoring system comprising: a light source; a light detector unit; a reference light guide, by which light of the light source is supplied to the light detector unit; a first measuring light guide, by which the light of the light source is directed to a substrate; a second measuring light guide, by which the light reflected or transmitted from the substrate is supplied to the light detector unit; a first light chopper arranged in the reference light guide; said first light chopper is a piezoelectric or electrostrictive or magnetostrictive light chopper; a second light chopper arranged in the first measuring light guide or second measuring light guide; said second light chopper is a piezoelectric or electrostrictive or magnetostrictive light chopper; and a revolving substrate carrier including a rotation mechanism connected with a processor unit configured to register a position of the substrate arranged on the revolving substrate carrier; wherein the first and second light choppers are connected with the processor unit, the processor unit is configured to generate a measuring phase, a reference phase, and at least one dark phase, and said processor unit is configured to digitally adjust the measuring phase, the reference phase, and the at least one dark phase depending on the position of the substrate and the processor unit is configured to synchronize a measuring point on the substrate to reduce a time jitter.