Patent ID: 8525073

Claim:
A system comprising: a working laser beam; a sensing laser beam; a first optical element for generating a coaxial beam from the working laser beam and the sensing laser beam; a second optical element for focusing the coaxial beam onto a workpiece, such that the working laser beam machines the workpiece and the sensing laser beam reflects from the workpiece; an optical sensor for sensing an intensity of the reflected sensing beam; a motion stage having an aperture, the motion stage positioned proximate the reflected sensing beam such that the motion stage translates an aperture along the sensing beam, wherein the intensity of the reflected sensing beam is maximized at the optical sensor when the aperture is at a focus position; and a data acquisition controller, wherein the data acquisition controller: is capable of determining a machining parameter of the working laser beam based on the focus position; and is capable of determining a degree of breakthrough based on the intensity of the reflected sensing beam and the focus position.