a method of fabricating a catadioptric lens system , the method involving : fabricating a single catadioptric lens element having a bottom surface and an upper surface , the upper surface having a convex portion and a concave portion , both the convex and concave portions sharing a common axis of symmetry ; cutting apart the catadioptric lens element to form 2n pie - shaped segments , wherein n is an integer ; and reassembling the 2n pie - shaped segments to form the catadioptric lens system with n of the 2n pie - shaped segments being located above a common plane and the rest of the 2n pie - shaped elements being below the common plane .