Polishing of lithium niobate by ion-beam etching

Ion etching is presently employed as a noncontact polishing method, on the assumption that the adjustment of the angle of incidence of the sawn surface to the angle for which the etch rate was greatest would allow all features to be suppressed, so that the resulting surface would tend to be flat. An Ar ion beam at 600 eV and 0.5 mA/sq cm was used for etching; from the geometrical construction, the facet at 38 deg etches about 2.4 times faster than the surface at zero deg. (O.C.)