Basics of ion beam figuring and challenges for real optics treatment

Abstract

Nowadays Ion Beam Figuring (IBF) is a well-known finishing technique for the production of ultra-precise optical surfaces. The diameter of optics can be in the range of 5 mm up to 2000 mm. Newest in-house developments extend the range down to 1 mm, which follows the upcoming market for micro optical systems. Besides IBF, ion beam etching technology (IBE) enables roughness improvement by different methods. Feature sizes from < 100 nm up to > 10 μm can be smoothed. However, operational parameters of IBF or IBE technology need to be adapted to the optical element. Beside the right choice of ion beam sizes (tool size) to remove equivalent feature sizes of the optics, also the shape (concave/convex) is of importance to consider side effects like re-sputtering or contamination originating from the ion beam source. This article will tabulate the state of the art of ion beam technology for ultra-precise optics manufacturing considering all parameters and side effects for efficient optics finishing.