Sputter polishing of surfaces

Theoretical estimates of the polishing of randomly rough surfaces by sputtering under uniform monodirectional ion bombardment are presented. The methods are based upon the Huygens wavefront construction and display the shrinkage of peaks and expansion of valleys. Peak shrinkage occurs rapidly and is less well predicted theoretically but valley expansion occurs over a longer time scale and is predictable from scaling laws developed for surface growth phenomena. The equivalent eroded depths required to reduce the roughness to specific levels are determined.