Pyramidal micro-mirrors for microsystems and atom chips
  Concave pyramids are created in the (100) surface of a silicon wafer by anisotropic etching in potassium hydroxide. High quality micro-mirrors are then formed by sputtering gold onto the smooth silicon (111) faces of the pyramids. These mirrors show great promise as high quality optical devices suitable for integration into MOEMS and atom chips. We have shown that structures of this shape can be used to laser-cool and hold atoms in a magneto-optical trap. 
M. Trupke, F. Ramirez-Martinez, E.A. Curtis, J.P. Ashmore, S.   Eriksson, E.A. Hinds, Z. Moktadir, C. Gollasch, M. Kraft, G....