Let's respect the OP first. Dan, what's your mirror EFL, diagonal distance inside focus, and desired FOV diameter? I'll ZEMAX up your system then do Rob's.

I looked at that website and am thoroughly unconvinced. His very first point is bogus - it's a lot easier to make flat parts very flat on a continuous ring polisher than to make spheres and conics. Been done there that - a guy that knows how to set, tool and weight his CP can pull 1/10 to 1/20 wave parts off all day, right to the edges. I ain't buyin' no 3 wave diagonal! Back in a while.

Mike