Patent ID: 8237080

Claim:
An improved method for forming a through hole in a workpiece, including the steps of producing a laser pulse with a laser, modifying said laser pulse with optics, and directing said laser pulse to impinge upon said workpiece, said through hole having a taper, a surface finish and an exit diameter, said workpiece including substantially homogeneous metallic material and having a top surface and an ablation threshold, said laser pulse having a spot size, a pulse duration and a peak power, the improvement comprising the further steps of: producing, with said laser, said laser pulse, said laser pulse having said peak power at least about 20% greater than said ablation threshold of said workpiece and said pulse duration greater than 10 nanoseconds; modifying, with said optics, said laser pulse to have said spot size having a 1/e 2 diameter at said top surface of said workpiece greater than about two times said exit diameter of said through hole; and directing said at least one modified laser pulse to remove material from an intended volume of said workpiece thereby creating said through hole with said exit diameter, said surface finish and said taper.