PURPOSE: To perform working without the effect of external light, by providing an interference filter, which selectively transmits a laser light wave, in front of a light receiving element, which receives the reflected light from a printing plate.
CONSTITUTION: The beam diameter of a laser beam 4 from a laser light source 2 is adjusted by a collimator lenses 3. The laser beam is reflected by a mirror 5, which is rotated and controlled by a galvanometer 6. The elliptic beam of 1×8mm is irradiated on an original point 12 on the printing plate 1. The laser beam 4 is moved in the lateral and longitudinal directions and the entire printing plate 1 is scanned. The beam is reflected and received by a light receiving part 10 of the light receiving element 7. The interference filter 11 is provided in front of the light receiving part 10 so that the laser wave is selectively transmitted. The amount of the light inputted to the light receiving part 10 is hardly affected by the external light.
FUJITA TOSHIJI
NOJIMA MASAKI
FUJIO SHIYOUSUKE
MASUDA TOSHIROU
| JPS58105007A | 1983-06-22 |
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