Large-Format Precision Laser Film Recorder

Abstract

A line of large-format raster-type film recorders, utilizing argon ion laser and rotating-drum techniques, is described. Image formats of up to 40X72 inches are available. The recorders are characterized by high absolute accuracy (down to 20 microns) high incremental accuracy (2.5 microns), continuously variable line-spacing and fairly high speed (up to 1 million points per second). Input is coded digital data from any source. Although developed for graphic arts applications, as part of a series of digital color image processing systems, these recorders can be readily adapted to other applications, including many that now use X-Y film plotters. One present version of the recorder enables exposing most common lithographic films with binary ("line") images as well as with half-tone images of any mesh number and angle. This version is already being applied to decorative, as well as to publications, printing preparation, to computer-aided cartography, and to seismographic and remotely sensed (aerial and satellite) data recording. Another version enables recording of variable density (continuous-tone) films. Future plans include adaptation to the expo-sure of offset plates, further increase in accuracy, and a five-fold increase in speed.