| 摘要 |
PURPOSE: To obtain a direct halftone gravure plate formation using a pulse laser, which does not require formation of a photosensitive film or an epoxy resin thin film layer. CONSTITUTION: The thermal energy applied to a plate surface is limited to about 10μJ by focusing the beam of double-wave (green visible light) YAG laser or blue light excimer laser down to about 5 to 10μm in diameter and limiting the irradiation time to 100nsec. or less. Engraving of 5 to 10μm in diameter formed in the plate surface is shifted by sequentially shifting the spot of irradiation in accordance with the size of a cell in such a manner that irradiation spots overlap one another. Thereby a cell of a desired size is obtained.
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