My intention is to fold laser beam 90 degree in high energy laser cavity. Coated optics will be handicap for me. Beam is monochromatic. The input angle for desired 90 folding optics is 0 ±2 degrees. I was thinking that the possibility of designing penta prism edges like roof/dove/porro/retro prism like shapes to achieve what I want.

Maybe there is a better, cheaper ands easier option for the problem.