The figuring of large optical components using mechanical techniques is a time and money consuming operation. Neutral Ion Beam Figuring (IBF) is shown to be a practical and flexible alternative to mechanical figuring. Ion Beam Figuring is performed by directing a broad beam high current ion source (Kaufman type) onto an optic in a carefully controlled manner, removing substrate material by ion beam sputtering, and resulting in a specified surface figure. The IBF technique is shown to have some interesting performance advantages over other methods, including very high removal rates, minimal surface damage, and no edge effects. Practical issues involving IBF are discussed and experimental results using the UNM prototype IBF machine to figure a 30cm fused silica optic are presented. Scaling problems are identified and discussed.
S. R. Wilson,
J. R. McNeil,
"Neutral Ion Beam Figuring Of Large Optical Surfaces", Proc. SPIE 0818, Current Developments in Optical Engineering II, (1 January 1987); doi: 10.1117/12.978903; https://doi.org/10.1117/12.978903