An illumination apparatus for illuminating a first surface with light from a light source, the apparatus comprising: a light splitter to split an incident beam traveling in an incident light path, into a plurality of beams; a first spatial light modulator which can be arranged in an optical path of a first beam out of the plurality of beams for forming a first light intensity distribution at a pupil plane of the illumination apparatus; a second spatial light modulator which can be arranged in an optical path of a second beam out of the plurality of beams for forming a second light intensity distribution at the pupil plane of the illumination apparatus; a light combiner to combine the first beam from the first spatial light modulator with the second beam from the second spatial light modulator, and to direct a resultant beam to an exiting light path; and a distribution forming optical system (4, 7, 8) to form a predetermined light intensity distribution including the first and second light intensity distribution on the pupil plane, based on the angular distribution of the first and second beams from the first and second spatial light modulators; wherein the light splitter includes a polarization separating film; wherein at least one spatial light modulator out of the first spatial light modulator and the second spatial light modulator includes a plurality of optical elements (33a, 34a) arranged two-dimensionally, which are controllable individually; and wherein the incident light path to the light splitter and the exiting light path from the light combiner extend in the same direction substantially parallel to the optical axis of the illumination apparatus. a light splitter to split an incident beam traveling in an incident light path, into a plurality of beams; a first spatial light modulator which can be arranged in an optical path of a first beam out of the plurality of beams for forming a first light intensity distribution at a pupil plane of the illumination apparatus; a second spatial light modulator which can be arranged in an optical path of a second beam out of the plurality of beams for forming a second light intensity distribution at the pupil plane of the illumination apparatus; a light combiner to combine the first beam from the first spatial light modulator with the second beam from the second spatial light modulator, and to direct a resultant beam to an exiting light path; and a distribution forming optical system (4, 7, 8) to form a predetermined light intensity distribution including the first and second light intensity distribution on the pupil plane, based on the angular distribution of the first and second beams from the first and second spatial light modulators; wherein the light splitter includes a polarization separating film; wherein at least one spatial light modulator out of the first spatial light modulator and the second spatial light modulator includes a plurality of optical elements (33a, 34a) arranged two-dimensionally, which are controllable individually; and wherein the incident light path to the light splitter and the exiting light path from the light combiner extend in the same direction substantially parallel to the optical axis of the illumination apparatus.