A method for printing a periodic pattern of linear features into a photosensitive layer which includes providing a mask bearing a pattern of linear features, arranging the substrate parallel to the mask, generating an elongated beam for illuminating the mask with a range of angles of incidence in a plane parallel to the linear features and with a uniform power per incremental distance along the length of the beam except at its ends where the power per incremental distance falls to zero according to first and second profiles over a fall-off distance, and scanning the beam in first and second sub-exposures to print first and second parts of the desired pattern such that the first and second parts overlap by the fall-off distance. The first and second profiles are selected so that their summation across the fall-off distance produces a uniform power per incremental distance.