are steeper during intensity peaks of the light beam as seen from the diagram three intensity peaks occur during the exposure of the first light sensitive point lsp 1 only two peaks occur during the exposure of the next light sensitive point lsp 2 and about two and a half peaks occur during the exposure of the third light sensitive point lsp 3 thereby the energy accumulated in the first point lsp 1 is higher than the energy accumulated in the third point lsp 3 which again is higher than the energy accumulated in the second point lsp 2 for several applications e g photolithography the energy differences however small they may be may easily cause unacceptable results e g periodic stripes on a printing plate etc the problem is closely connected to the relation between the frequency of the intensity peaks and the scanning speed of the light modulation layout if e g several hundreds of peaks occur within the exposure of each light sensitive point lsp one or two more or less may not cause unacceptable energy differences but typically the desirable peak frequency and the desirable scanning speed is related in such a way that the problem is significant and unacceptable in an embodiment of the present invention synchronizing the scanning speed with the peak frequency solves the problem this solution is shown in fig5 the scanning speed is adjusted in such a way that the exposure time for one light sensitive pixel corresponds to exactly an integer number of peaks e g three.