Abstract: A method of producing an array of islands (12) on concentric tracks (13) on a rotating substrate by selective exposure of an electron-sensitive surface of the substrate to an electron beam comprises directing the beam onto a point (A) on the surface within a zone of action of the beam and deflecting the beam in the sense (31) of substrate rotation to remain on the point until the point (A?) has received an electron dose from the beam. The beam is then redirected onto a further point (B or T) at a spacing from the preceding point (A?) and dosed by the beam in similar manner. The redirection and deflection procedure is repeated for at least one substrate revolution, preferably several revolutions, so that points are dosed along at least one of the tracks (13a), preferably several of the tracks (13a to 13j).