Posted By David Simons
Thanks for bringing this up. If I did not already have an off-axis telescope project in the works, I probably would have jumped on this, just to "try it out". I love exotic designs, and the price is right.
The picture is of a 4" thick Zerodur substrate large enough to make a nearly 12" f8.3 off axis scope. It is from a 1/3 "section" of a 25" f4 mirror. It weighs about 50lbs. I have yet to check to see if this is actually a parabola or spherical surface.