A dual viewpoint solid catadioptric lens has a first spherical refractive surface S1 having a center C1 located on an optical axis of the lens and having a radius r1, and a second spherical refractive surface S2 having a center C2 located on the optical axis of the lens and having a radius r2<r1. The...http://www.google.fr/patents/US7268956?utm_source=gb-gplus-shareBrevet US7268956 - Solid catadioptric lens with two viewpoints
