Illumination system comprising a plate integrator (100) for forming a plurality of secondary light sources (104,104a,104b) and a coherence remover (102) having a plurality of transparent rods (102a-c) with different optical path lengths. A first lens (101 ) between integrator and coherence remover focuses each of the plurality of secondary sources on a respective one of the plurality of rods of the coherence remover. A second lens (103) located after the coherence remover recombines the plurality of incoherent beams in the mask plane (106).