Patent ID: 8325324
Filing Date: 2012-12-04
Classification: G03F

Abstract:
1. An illumination optical apparatus which illuminates a surface to be illuminated, comprising: a path switching member arranged in a path of illumination light and switching an optical path of an exiting beam between a first optical path and a second optical path; a path combining member arranged at an end of the first optical path and an end of the second optical path and combining the first optical path and the second optical path; a first pupil distribution forming member arranged in the first optical path and forming a predetermined light intensity distribution on an illumination pupil; and a second pupil distribution forming member arranged in the second optical path and forming a predetermined light intensity distribution on the illumination pupil, the path switching member comprises a first reflecting mirror which can be switched between a first posture in which the first reflecting mirror reflects an incident beam toward the first optical path and a second posture in which the reflecting mirror reflects the incident beam toward the second optical path; the path combining member comprises: the illumination optical apparatus comprises a polarization changing member arranged in at least one optical path out of the first optical path and the second optical path and changing a polarization state of a beam.