Dear all, We want to coat Si and GaAs surfaces with an anti reflection coating in IR region of the spectrum. The coating should work on 4um for Si and 8um for GaAs surface. Coating material may be ZnS or some other. If anybody has a knowledge of design recipe or a reference to be suggested we will be glad to hear about that. Thanks a lot, Oray Orkun Cellek o.o.cellek@ieee.org