Regarding polishing of BaF2 windows.  

I was told by the manufacturer that BaF2 windows should be beveled before
polishing.  This will minimize breakage.  In my experience, you can find
unpolished windows for about 1/4 the cost of polished ones.  It is
imperative that the polishing wheel be absolutely clean, or you will get
scratches.  I agree with Mike Palin that you will never get as good a
finish as what you can buy professionally, but it is good enough. You can
think of the BaF2 as delicate fluorite and proceed accordingly.  MgF2 is
not transparent to radiation at 10.6 microns.

Sincerely,

Zachary Sharp
Zachary Sharp
Institut de Minéralogie
Université de Lausanne
CH-1015 Lausanne
Switzerland
Phone 011 41 21 692 4450
FAX 011 41 21 692 4305