No, it's just a planar window.
I can just about deal with slicing a bit off a boule to get a nice flattish
slice, and then machining it to diameter and polishing.
Figuring into a lens would be a bit more than I can do.

Way too much work, just order the thickness and diameter of
a polished wafer from either Saphikon or Meller Optics.

Saphikon was purchased by Saint Gobain, a French conglomerate similar to
General Electric. The new company name is Saint Gobain Crystals, still located
in the same place in MIlford, New Hampshire. (603 673 5831). I used to work for
them but didn't survive the semiconductor industry collapse. Not a big deal
since I've really been enjoying retirement.

Earle Rich
Mont Vernon, NH