Patent ID: 7605979

Claim:
A device for directing radiation to a layer ( 1 ) including: a first optical element (L 1 ) for focusing a first radiation beam (B 1 ) originating from a first radiation source (S 1 ) onto said layer, a second optical element (L 2 ) for focusing a second radiation beam (B 2 ) originating from a second radiation source (S 2 ) onto said layer, wherein the wavelengths of the radiation from said first and said second radiation source are different from each other, the first and second optical element being jointly movable with respect to said radiation sources, wherein the focal points of the two radiation beams at least substantially coincide with various movements of the first optical element and the second optical element with respect to the radiation sources, characterized in that the second optical element has an aperture (A 2 ) for optically undisturbed passage of the first radiation beam (B 1 ) and that the intensity of the second radiation beam (B 2 ) at the position of the aperture (A 2 ) is substantially zero.