Concepedia

Antireflection Coatings for Strongly Curved Glass Lenses by Atomic Layer Deposition

Kristin Pfeiffer, Ulrike Schulz, Andreas Tünnermann, Adriana Szeghalmi

Coatings · 2017 · 78 citations · 40 references

Open access

TL;DR

Antireflection coatings are essential for many optical systems and are increasingly required on highly curved components. Atomic layer deposition was used to deposit uniform thin films of SiO₂, Al₂O₃, TiO₂, and Ta₂O₅ on arbitrarily shaped surfaces via self‑limiting surface reactions. Al₂O₃/TiO₂/SiO₂ and Al₂O₃/Ta₂O₅/SiO₂ AR coatings fabricated by ALD achieved <0.6 % reflectance (average 0.3 %) on a 4 mm fused‑silica hemispherical lens and <1 % (average <0.3 %) on a 50 mm B270 aspherical lens, demonstrating that ALD can produce low‑reflectance, uniform coatings on strongly curved optics without complex thickness monitoring.

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 SiO2, Al2O3, TiO2 and Ta2O5 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. Al2O3/TiO2/SiO2 and Al2O3/Ta2O5/SiO2 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.