A Gallium-Arsenide Laser Facsimile Printer

This paper describes the printing of miniature, high-resolution, pictorial images1 by machining with a gallium-arsenide laser. The focused beam from a pulse-modulated laser is raster-scanned over a thin metal film deposited on a transparent plastic substrate. The energy in each burst of laser power is controlled in correspondence with a transmitted signal so as to machine an array of holes in the metal film.2 This signal may correspond to the optical reflectivity of a remotely located, synchronously scanned, original document, or it may represent the machining instructions of a graphics-generating computer. A capability for high resolution is intrinsic to this printing method. The machined image can readily contain 1600 hole sites per line and 2000 lines per frame, and is similar in appearance to a frame of microfilm or microfiche. The pulse repetition rate, raster scanning speeds, and maximum pulse energy are chosen such that the holes machined in "all-white" regions of the image are nearly contiguous. These regions are about 50 percent transparent to visible light. Unmachined regions are