Diamond films for IR optical applications

Since materials with the best optical properties have low-fracture toughness, the need for protective coatings for IR windows and domes has been recognized for a long time. The emergence of technology for deposition of polycrystalline diamond (PCD) coatings by microwave-assisted chemical vapor deposition presents an opportunity to provide protective coatings for IR materials. Results of deposition of PCD films on various substrates will be presented. Diamond film morphology can be tailored from very smooth (35-a RMS roughness) to textured with very large crystallites (20-μm diameter) with deposition rates from 0.5 to 2 μm/hr. Substrate surface preparation using a nonabrasive refractory interlayer technique will be described. Film morphology, characterization, and polishing that uses a chemical polishing technique will also be discussed.