I am interested in acoustic microscopy and would like to know if anyone
can provide any information about the current state-of-the-art for
fabricating a a microlens (1-mm diameter and 1-mm radius of curvature
concave surface) in [100] silicon, using some sort of dry or wet etching
technique, or perhaps even mechanical grinding followed by Syton (super)
polishing. Ideally, the surface would also be very smooth (rmn roughness
~1-nm) and have accurate sphericity. All comments appreciated!

Thomas Wilson, Ph.D.
Marshall University
Department of Physics