Abstract: A wide angle radiant energy detection apparatus arranged as a catadioptric assegrainian telescope having a plane secondary mirror is disclosed which utilizes a correcting lens as a structural support for the secondary mirror to reduce losses caused by mirror support structure vignetting. Angular resolution at wide field angles is increased by lenses which reduce oblique spherical aberation, spherical aberation, and coma, and by the more uniform energy distribution across the image field caused by the lack of vignetting optical support structure.