4.2 Monitoring of optical thin films using a quartz crystal monitor

Quartz crystal monitoring in the production of dielectric multilayer stacks is compared to optical monitoring. The stacks are calculated with the aid of an optimizing program. This yields optical thicknesses of the layers differing from multiples of a quarter of the wavelength. Optical monitoring is complicated in this case. Using quartz crystal monitoring, planning and execution of the process is earsier and yields stacks with satisfactory reflectance characteristics faster than with optical monitoring.The reproducibility of the optical thickness of MgF₂ layers is investigated. In general, both methods turn out to be equivalent in performance.