Patent ID: 8389893
Filing Date: 2013-03-05
Classification: B23K,G02B,G03F

Abstract:
1. A method for laser beam machining of a workpiece, comprising: focusing a laser beam to a focal point by an objective, which has a focal plane, into or onto the workpiece to produce a machining effect by two-photon processes, the work piece having a boundary surface; shifting the position of the focal point with respect to the workpiece; projecting an illuminating modulation object to the workpiece and into the focal plane or so as to intersect the focal plane to obtain a reference for the position of the focal point; imaging reflections of the projection occurring at a boundary surface into an autofocus image plane; detecting the imaged reflections by a camera having a camera image plane, wherein the camera image plane either intersects the autofocus image plane when the projection of the illuminating modulation object lies in the focal plane, or lies in the autofocus image plane when the projection of the modulation object intersects the focal plane.