KLA Corporation
REFLECTIVE COMPACT LENS FOR MAGNETO-OPTIC KERR EFFECT METROLOGY SYSTEM

Abstract:

A Cassegrain or quasi-Cassegrain structure objective lens is used in a polar MOKE metrology system. The quasi-Cassegrain reflective objective lens includes a primary concave mirror and a secondary mirror. The primary concave mirror has a wider diameter than the secondary mirror and defines an aperture through which the laser beam is configured to be transmitted toward the secondary mirror. The secondary mirror can be convex, concave, or have a flat surface.