Patent ID: 9488811
Filing Date: 2016-11-08
CPC Classification: G03F

Claim Text:
1. A Wynne-Dyson microlithographic optical system having a nominal 1× magnification that can be varied, comprising along an optical axis: a concave mirror having concave surface; a positive lens group axially spaced apart from the concave surface of the concave mirror; first and second total-internal-reflection (TIR) prisms disposed adjacent the positive lens group opposite the concave mirror and on respective sides of the optical axis; wherein the positive lens group includes a split lens that defines first and second split lens elements that reside on respective sides of the optical axis and respectively adjacent the first and second TIR prisms, the first and second split lens elements being axially movable in opposite directions to vary the magnification from the nominal 1× magnification by up to about 500 parts per million.