GB1316412A - Facsimile reproduction - Google Patents

Abstract

1316412 Lasers D J BRADLEY 30 Sept 1970 [30 June 1969] 32980/69 Heading H1C [Also in Division H4] A mode locked laser beam generator for use in a facsimile reproduction apparatus, comprises a neodymium laser rod 11 cut at the Brewster angle inserted in a laser cavity and pumped by a xenon flashtube. The laser cavity is defined by two dielectric coated mirrors 12, 13. At the wavelength of the laser, 10,600 Š, the output mirror 13 has a reflectivity of about 50% and the mirror 12 has 100% reflectivity and is immersed in a saturatable dye solution cell 14 so as to produce mode locked pulses. The output from the laser is split in a beam splitter and each part is passed through a nickel sulphate attenuator cell to remove the peak power of the pulses. One part of the split laser beam is passed into a scanning unit and then focused by a lens into a spot which is scanned across an original pattern, e.g. a typescript or drawing. A detector picks up the reflected laser light and the output from the detector is used to modulate the other part of the split laser beam which is passed to a scanning unit and then focused by a lens into a spot which is scanned across a first material, e.g. carbon paper or ink-coated mylar which is evaporated on to an adjacent material, e.g. paper to build up a facsimile of the original pattern. Pressure sensitive paper may alternatively be used for building up the facsimile and the output of the laser may be monitored on an oscilloscope. The apparatus may be modified for three-dimensional, multicoloured or multi-material reproductions.