Practical optimization of a coating deposition process by application of hybrid monitoring strategies in an industrial production environment

The applicability of broadband optical monitoring to an industrial optical coating production environment is investigated. Different monitoring strategies have been applied to the deposition of beamsplitters and longpass edge filters by electron beam evaporation without any plasma or ion assistance. While the shift and reproducibility in the optical constants were poorly specified, pure optical broadband monitoring of the coatings did not prove superior to traditional quartz crystal monitoring. On the contrary, the introduction of a hybrid monitoring strategy that combines quartz crystal and broadband optical monitoring led to significant improvements in the coating performance reproducibility compared to a pure quartz crystal monitoring approach. Accompanying computational manufacturing experiments performed for the beamsplitter design reveal the same trend.