An exact geometrical ray analysis has been used to derive the profiles for telescope secondaries that perfectly recollimate beams incident on fast concave spherical mirrors. Both Cassegrainian and Gregorian configurations are possible. The high magnification designs tend to redistribute the energy profile and may be used, for example, to make Gaussian beams more uniform.
© 1979 Optical Society of America
W. H. Southwell, "Beam expander telescope design utilizing fast spherical primaries," Appl. Opt. 18, 1240-1240 (1979)