ALD Protective Coatings for Curved Calcium Fluoride Optics

The patent replaces the mechanical PVD coating system with a chemical vapor deposition (CVD) system. Instead of using physical vapor deposition mechanisms that struggle with conformal coating on complex geometries, the invention employs chemical reactions of organometallic precursors with calcium fluoride surfaces to deposit coating layers. This chemical approach enables uniform and conformal coating on steeply curved surfaces and components with complex shapes, resolving the thickness uniformity issue while simplifying the coating process.

The patent changes the fundamental parameters of the coating process by transitioning from PVD to CVD methodology. The CVD process uses lower deposition energies and chemical reactions instead of high-energy physical deposition, thereby reducing mechanical stress on the coating and substrate. This parameter change eliminates mechanical stability issues and surface contamination problems while maintaining the protective function that extends service lifetime.

The patent merges the coating application into a single, unified CVD process that can coat all surfaces of complex components simultaneously. Unlike PVD which requires multiple runs and repositioning, the CVD system delivers precursors that chemically react uniformly across all exposed surfaces in one continuous process. This merging of coating operations eliminates re-work requirements and ensures consistent thickness across complex geometries like prisms, thereby improving productivity while maintaining reliable protection.