Antireflection coatings for strongly curved glass lenses by atomic layer deposition

Abstract

Antireflection (AR) coatings are indispensable in numerous optical applications and are increasingly demanded on highly curved optical components. In this work, optical thin films of SiO 2 , Al 2 O 3 , TiO 2 and Ta 2 O 5 were prepared by atomic layer deposition (ALD), which is based on self-limiting surface reactions leading to a uniform film thickness on arbitrarily shaped surfaces. Al 2 O 3 /TiO 2 /SiO 2 and Al 2 O 3 /Ta 2 O 5 /SiO 2 AR coatings were successfully applied in the 400-750 nm and 400-700 nm spectral range, respectively. Less than 0.6% reflectance with an average of 0.3% has been measured on a fused silica hemispherical (half-ball) lens with 4 mm diameter along the entire lens surface at 0° angle of incidence. The reflectance on a large B270 aspherical lens with height of 25 mm and diameter of 50 mm decreased to less than 1% with an average reflectance < 0.3%. The results demonstrate that ALD is a promising technology for deposition of uniform optical layers on strongly curved lenses without complex in situ thickness monitoring.