PROJECTION OPTICAL SYSTEM AND PROJECTION ALIGNER

PROBLEM TO BE SOLVED: To suppress variation of a focal position based on a change of ambient temperature and a temperature change of a lens caused by absorption of exposure light in a projection optical system. SOLUTION: The exposure light having prescribed wavelength from a light source 16 is incident on the projection optical system 15 through a reticle R. The exposure light deflected by a first plane mirror M1 is guided to a concave mirror M0 through a condensing power lens group 19C and a divergent power lens group 19D. The exposure light reflected by the concave mirror M0 is projected to a substrate P such as a silicon wafer through the divergent power lens group 19D, the condensing power lens group 19C and a second plane mirror M2. Thus, a pattern drawn on the reticle R is projected to the substrate P to expose the substrate P. COPYRIGHT: (C)2011,JPO&INPIT