A cone optical system comprising:(a) a convex conical mirror having a symmetry axis,(b) a refracting element having at least one conical surface, with a common symmetry axis with said convex conical mirror, said mirror and refracting element having apex angles selected such that a first paraxial light beam impinging said convex mirror in a direction substantially perpendicular to said symmetry axis is reflected toward said refracting element, traverses same and emerges therefrom as a second paraxial light beam, and(c) a collecting lens on the side of said refracting element opposite said mirror and adapted to focus said second light beam onto an image point located on said symmetry axis.