Optical system and projection exposure device

Abstract

The optical system 20 is an optical system of the projection exposure apparatus 10 disposed between the mask 40 and the wafer W. It includes: a projection system 24 having a plurality of mirrors that receive a first reflected light L1 for exposure reflected from the mask 40 by the illumination light L0 from the first light source 31 and guide it toward the wafer W; wherein the projection system 24 receives a second reflected light L3 reflected from the wafer W by the first measurement light L2 from the second light source 25 and guides it toward the outside of the projection system 24 by the plurality of mirrors, and the first measurement light L2 is used for the alignment of the wafer W.

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