Patent ID: 9091936
Filing Date: 2015-07-28
Classification: G03F

Abstract:
1. An illumination system having a pupil surface, the illumination system comprising: a light source configured to produce projection light that propagates through the illumination system along a light path; a beam deflection array comprising a plurality of beam deflection elements, each beam deflection element being reflective, each beam deflection element being configured to deflect an impinging light beam by a variable deflection angle, and the beam deflection array being configured to determine an irradiance distribution in the pupil surface in a first mode of operation of the illumination system; an optical raster element configured to determine the irradiance distribution in the pupil surface in a second mode of operation of the illumination system; and an exchange unit configured to hold the optical raster element in the light path in the second mode of operation of the illumination system, wherein: