The controlled removal of material from the surface of insulators has been observed by using a positive ion beam. In the energy range 0.5–2.0 MeV the sputtering yield was observed to be unity. The application of this technique to the manufacture of high quality optical surfaces is discussed.
J. B. Schroeder, S. Bashkin, and J. F. Nester, "Ionic Polishing of Optical Surfaces," Appl. Opt. 5, 1031-1034 (1966)