OPTICAL ELEMENT FOR FOCUSING APPROXIMATELY COLLIMATED RAYS

摘要

PROBLEM TO BE SOLVED: To provide a one-piece optical element for focusing an input bundle of collimated rays around an optical axis in a focal region around a focal point.SOLUTION: An optical element OE is bounded on an entry side by a truncated cone KS centered on an optical axis OA and having a top surface KS.p pointing toward a light entrance LE, and bounded on the exit side by a cone K having a cone tip pointing toward a light exit LA on the optical axis OA and a rotationally symmetric aspheric boundary surface AG located around the cone K. The cone K is formed as a complementary cone to the truncated cone KS. The aspheric boundary surface AG is formed as a partial surface of a convex surface of a plano-convex aspheric converging lens with a focal point F located behind the light exit LA of the optical element OE on the optical axis. The lateral surfaces KS.m, K.m of the truncated cone KS and of the cone K are formed to cause inward reflection and are spaced apart along the optical axis OA so that the approximately collimated input bundle EB is directed from an inner side of the lateral surface K.m of the cone K to an inner side of the lateral surface KS.m of the truncated cone K.SELECTED DRAWING: Figure 3