Method and apparatus for imagewise exposing a photosensitive medium to a laser radiation according to image signals representative of nominal densities of original images, such that the medium is scanned in mutually perpendicular first and second directions at respective first and second scanning intervals....http://www.google.de/patents/US5057851?utm_source=gb-gplus-sharePatent US5057851 - Method of exposing photosensitive medium for optimum density of reproduced image
