I just came across this design. The object is to get a big aperture reflector with observing possible from ground. Looks like it was before the days of mirrors faster than f4? Achieved with a "compact" approach to have the primary mirror very low, and with a secondary set at an angle where the converging rays are bent not 90 deg, but less - down to only 60 deg. Images and explanation in the link below.
Interesting.
http://www.biophysik.uni-freiburg.de...owrider_e.html