Conformal antireflection coating on polycarbonate domes

Optical surfaces are achieving increasingly complex shapes which brings out challenges to functionalize them conformally for improved performance. Besides, plastic optics pose a great challenge on coating technologies due to their large coefficient of thermal expansion and poor adhesion of functional coatings. Here, the potential of plasma enhanced atomic layer deposition (PEALD) technique to develop uniform and 3D-conformal films on polycarbonate (PC) (Makrolon) planar and dome substrates has been explored. It enables to grow conformal Al2O3, TiO2 and SiO2 films on steeply curved PC substrates. Moreover, we demonstrate an 11-layer antireflection (AR) coating reaching about 0.2% reflection at 905 nm wavelength on the entire outer surface of several PC domes along with a consistent optical performance on the inner surface. The adhesion and environmental stability tests according to ISO-9211-04 resulted in promising adhesive and environmentally durable films on PC dome optics. These results suggest a possible way to grow uniform, dense, conformal, and stable optical coatings on sensitive polymer PC substrates for desired optical applications.