Patent ID: 6822669
Filing Date: 2004-11-23
Classification: B23K,B41C,G03F

Abstract:
A method for the ablation of a surface on a rotating drum having an axis, which comprises:locating a number of laser fiber exits beside one another in an AOM array having a number of AOMs corresponding to the number of laser fiber exits; simultaneously emitting a plurality of laser beams from the laser fiber exits; dividing up each of the laser beams into at least two partial beams after the laser beams emerge from the laser ffber exits; modulating the partial beams independently of one another; imaging the modulated partial laser beams on the surface of the drum with an optical system having an entry pupil; aligning the laser fiber exits to converge in a fan shape for intersecting some of the partial beams in a vicinity of the entry pupil; aligning the partial beams in a fan shape to cover at least two planes, points of incidence of the partial beams on the surface in each plane respectively lying on an axis forming an angle &agr; with the axial direction of the drum, where arctan &agr;=lx/2ly. lx being a center spacing of the points of incidence in a direction of the axes; and ly being a center spacing of the points of incidence in a direction perpendicular to the axes; and laser engraving the surface with the multi-spot array by moving the laser fiber exits, the AOM array, and the optical system together in an axial direction of the drum while scanning the surface with the multi-spot array in a circumferential direction of the drum.