I am interested in acoustic microscopy and would like to know if anyone
can supply any information about state of the art in fabricating a 1-mm
diameter and 1-mm radius of curvature concave surface in [100] silicon,
using some sort of dry or wet etching technique and ideally obtaining a
very smooth (rmn roughness ~1-nm) surface and sphericity. Thanks.

Thomas Wilson
Marshall University
Department of Physics