Patent ID: 7134752

Claim:
A non-powered optical lens element comprising: a first surface having an axis of symmetry; and a second surface of complementary curvature to the first surface and having an axis of symmetry; wherein at least one surface has a central portion and lateral ends spaced therefrom, said surface exhibiting significant deviation in surface curvature from a standard optical surface of quadratic form wherein the curvature increases from the central portion toward the lateral ends, and wherein there is a maximum value of curvature intermediate the central portion and the lateral ends; and wherein the deviated surface has tangential and sagittal radii varying across the deviated surface so that Q ( r )≡ r s 3 /r T R (0) 2 is non-constant, being unity at the vertex and changing by at least 0.25 away from the axis of symmetry, where r T and r S are the tangential and sagittal radii of curvature; and R(0) is the vertex radius of curvature.