The assembly to homogenize a light beam, especially from an excimer laser, has at least two optical functional surfaces (26) in succession along the light path (z). Two groups of refractive or diffractive imaging elements are at the optical surfaces as cylinder lenses (30, 30′, 32), with at least two imaging elements of different characteristics within at least one of the groups. The light beam is finally carried through a Fourier lens (28) to the working plane (29).