GB1094984A - Apparatus for photographic copying by means of a laser - Google Patents

Abstract

1,094,984. Copying by scanning. JARROLD & SONS Ltd. Jan. 20, 1965 [Jan. 21, 1964], No. 2498/64. Heading H4F. [Also in Division G2] A copy of an original (opaque or transparent) is made by scanning with a laser beam. In the simplest form, the beam passes directly through a transparent original to a photosensitive sheet, which may or may not be in contact with the original. In the arrangement illustrated, an image of a transparent or opaque original is projected along a path 5 from a projector 4, and reflected by mirrors 1 and 6, to fall on a screen 7 having a small aperture 8. Behind this is a photomultiplier 9. Mirror 1 is fixed on a rotating shaft 2, and mirror 6 can oscillate as indicated by the arrows. Thus the two mirrors, acting in combination, can scan the image of the original line by line across the aperture 8. A beam of light 5<SP>1</SP> from a laser 10 passes through a focusing system 11 and a light-modulating device 12 (Kerr cell or crystal modulator), and is reflected from a mirror 1<SP>1</SP> to fall on a sheet of photographic material 13. Mirror 1<SP>1</SP> is also mounted on shaft 2, and thus rotates in synchronism with mirror 1. Sheet 13 is given an oscillating motion in synchronism with mirror 6, and thus the beam 5<SP>1</SP> carries out a line by line scanning movement across sheet 13 corresponding to the scanning of beam 5 across aperture 8. The signals received by photomultiplier 9 are fed through an amplifier 16 to the modulating device 12, so modulating the laser beam. Thus an exposure is made on sheet 13 corresponding to the original. A screen may be placed over sheet 13 to produce half-tone effects. By using suitable colour filters 14, separate colour records may be made