Directly monitoring the optical thicknesses of deposited layers on the working samples while they are being grown

摘要

This paper presents an analysis of the errors of photometrically monitoring the layer thicknesses during the vacuum deposition of multilayer interference systems. It is shown that, when the thicknesses of the growing layers are monitored from the change of the spectral response of the transmittance (reflectance) in a definite wavelength interval, a signal-measurement error no greater than 1% results in substantial errors in monitoring the thicknesses of the layers being deposited. The errors are less significant if the thicknesses are monitored by a through-layer method at calculated fixed wavelengths. An optical system is proposed that makes it possible to monitor the thicknesses of the coating layers while they are being deposited, using reflection directly from the working items or from a witness located alongside the items on the rotation dome.