US Patent 7268956 Solid catadioptric lens with two viewpoints

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 lens also has a first ellipsoidal reflective surface E1 with foci F1 and F1′ on the optical axis of the lens, and a second ellipsoidal partially reflective surface E2 having foci F2 and F2′ on the optical axis of the lens. Focus F1 coincides with C1, focus F2 conincides with C2, and focus F1′ coincides with F2′. The points C1 and C2 provide dual viewpoints for the lens, which may be used in a variety of imaging applications.