Gabor’s 1941 catadioptric design can be modified to give much higher performance versions. Some designs are shown that are .999 NA in air over a wide field with diffraction-limited correction on a curved image.
David Shafer, David Shafer,
"Dennis Gabor’s catadioptric design and some new variations", Proc. SPIE 10590, International Optical Design Conference 2017, 105901C (27 November 2017); doi: 10.1117/12.2302384; https://doi.org/10.1117/12.2302384