Optical element of reduced thickness

Claim 1

A lens element matrix of discrete elements comprising a plurality of discrete elongate elements, each element having first and second ends with a plurality of elongate side surfaces therebetween; means for permitting alignment of said elongate elements in side-by-side relation with said second ends forming a common surface and said elongate side surfaces of each element in contiguous contacting relation with adjacent elements, said side surfaces permitting relative movement between said elements in the direction of the elongation of said elements and said elongate side surfaces inhibiting relative rotation of said elements about the direction of elongation of said elements; means for holding the elements to prevent relative movement at said side surfaces in the direction of elongation of said elements, said first ends together forming incremental discrete segments of a continuous optical surface, the maximum lens thickness variation being less than one-half the surface diameter, said surface having a thickness variation t parallel to an opTic axis, said thickness substantially defined by the terms A (xy2 + 1/3 x3) + Dx + E wherein x and y represent points on a rectangular coordinate system in a plane normal to the optic axis, A is a constant representing power variation in the x direction, D is a constant representing the coefficient of a prism removed to minimize thickness and may have a value of zero, and E is a constant representing thickness of the optic axis; the peak of the first common ends of each element being aligned to a common surface.