METHOD FOR PRODUCING PARALLEL-SIDED MELT ZONE WITH HIGH ENERGY BEAM

摘要

A method is disclosed for controlling a high energy radiation beam to produce a melt zone with parallel sides in a workpiece having first and second opposed surfaces between which the zone extends. The method comprises (a) directing the beam at a slight angle to the normal through the first surface of the workpiece with the focus of the beam being at or adjacent the second surface; (b) oscillating the beam and workpiece relative to each other about a point located on the beam axis at or adjacent the first surface and in a plane perpendicular to the lateral line of advancement of the directed beam so that opposite sides of the melt zone in the plane will each be sequentially rotated to assume an orientation substantially perpendicular to the first surface; and (c) laterally advancing the directed beam along a on the first surface of the workpiece while carrying out the oscillations of step (b) at a selected frequency above a minimum.