Patent ID: 7608800
Filing Date: 2009-10-27
Classification: B23K

Abstract:
1. A method for selectively processing one or more of a set of structures on or within a workpiece by irradiating selected structures in the set with pulses from a laser, the set of structures being arranged on the workpiece in a linear pattern having an approximately equal pitch between adjacent structures, the pulses propagating along a laser beam propagation path terminating at a laser beam spot on the workpiece, the laser being characterized by a PRF parameter that specifies a PRF at which pulses produced by the laser have desirable pulse properties for processing the structures, the method comprising: firing a first processing laser pulse when the laser beam spot coincides with a first structure location; selectively blocking or clearing the laser beam propagation path during the first laser pulse; moving the workpiece and the laser beam spot relative to one another such that the laser beam spot moves toward a second structure location at a speed less than the product of the PRF parameter and the pitch; firing a laser pre-pulse before the laser beam spot reaches the second structure location; blocking the laser beam propagation path during the laser pre-pulse; firing another processing laser pulse when the laser beam spot coincides with the second structure location; and selectively blocking or clearing the laser beam propagation path during the second processing laser pulse.