ILLUMINATION OPTICAL DEVICE AND EXPOSURE DEVICE

摘要

Provided is a illumination optical system which can maintain a high use efficiency of a pulse-emitted illumination light and reduce the affect of illuminance irregularities caused by the spatial coherency of the illumination light without complicating the device configuration. An illumination optical system (ILS) illuminates a plane to be illuminated by using pulse-emitted illumination light (IL). The illumination optical system (ILS) includes: a spatial light modulator (13) having a plurality of mirror elements (3) which applies a spatial modulation to the illumination light (IL) in accordance with the position where the illumination light is inputted; and a modulation control unit (31) which applies different spatial modulations to the illumination light (IL) by the mirror elements (3) so that each time at least one pulse of the illumination light (IL) is emitted, the intensity distribution of the illumination light (IL) is substantially uniform on a predetermined plane.