A Wide-field Corrector at the Prime Focus of a Ritchey–chrétien Telescope

We propose a form of a lens corrector at the prime focus of a hyperboloidal mirror that provides a flat field of view up to 3◦ diameter at image quality D80 < 0.8 arcsec in integrated (0.32– 1.10 μm) light. The corrector consists of five lenses made of fused silica. Only spherical surfaces are used, so the system is capable of achieving better images, if necessary, by aspherizing the surfaces. The optical system of the corrector is stable in the sense that its principal features are retained when optimized after significant perturbations of its parameters. As an example, three versions of the corrector are designed for the V.M.Blanco 4-m telescope at Cerro Tololo InterAmerican Observatory with 2◦.12, 2◦.4, and 3◦.0 fields of view. c © 2004 MAIK “Nauka/Interperiodica”.