Control of multilayer vapour deposition - by alternate exposure and check measurement of two test glasses

摘要

A measuring system for the mfr. of multilayer structures of alternating high- and low-refractive layers on transparent substrates by vapour deposition used two test glasses. These are alternately exposed simultaneously to a measuring light beam and to the rate of vapour deposition as the substrates. A changeover control ensures that one test glass receives the high and the other the low refractive layer. This clearly reveals maxima and minima in the intensity curve of the measurement signal so that the amplifier gain in the processor circuit requires no subsequent adjustment. Sensitivity and gain remain constant and noise interference with the signals is negligible.