Electro Scientific Industries, Inc.

Steve Stone

Keith Grant

Brady Nilsen

Kelly Bruland

Steve Swaringen

A laser processes a workpiece with laser pulses delivered at random time intervals and at substantially constant energy levels by characterizing the laser cavity discharge behavior and utilizing that information for adjusting dummy pulse time periods to compensate for the energy errors. Dummy pulses are laser pulses that are blocked from reaching a workpiece. A second way for providing constant pulse energies employs an AOM for varying amounts of laser energy passed to the workpiece. A third way of providing constant pulse energies entails extending the pulse period of selected pulses to allow additional laser cavity charging time whenever a dummy pulse is initiated.

High energy pulse suppression method

A method selectively processes structures on a workpiece with laser pulses. The structures are arranged in a linear pattern having approximately equal pitch. The pulses propagate along a laser beam propagation path terminating at a laser beam spot on the workpiece. The method fires a first processing pulse when the spot coincides with a first structure location, selectively blocks or clears the propagation path during the first pulse, moves the workpiece and the spot relative to one another such that the spot moves toward a second structure location at a speed less than the product of the laser's PRF and the pitch, fires a dummy pulse before the spot reaches the second structure location, blocks the propagation path during the dummy laser pulse, fires another processing pulse when the beam spot coincides with the second structure location, and selectively blocks or clears the propagation path during the second processing pulse.

Methods and systems for decreasing the effective pulse repetition of a laser

A method and system decrease the amount of undesired laser radiation reaching a workpiece from a laser having a laser cavity and a Q-switch. The laser operates at any given time in one of at least two modes. In a first mode the laser emits pulses at a PRF (pulse repetition frequency) for selectively irradiating targets on or within a workpiece, and the pulses propagate along a propagation path to the workpiece. In a second mode less or no laser radiation desirably reaches the workpiece. The method is operable during the second mode. The method opens the Q switch more than the Q switch is open in the first mode, thereby limiting the amount of energy that builds up in the laser cavity and decreasing the peak energy of the laser radiation emitted in the second mode.

Method and system for preventing excessive energy build-up in a laser cavity

Methods and systems operate a machine having a laser characterized by a PRF (pulse repetition frequency) parameter that specifies a PRF at which pulses produced by the laser have desirable pulse properties for irradiating structures on or within a workpiece. The structures are arranged on the workpiece in a linear pattern having an approximately equal pitch between adjacent structures. The laser emits a laser pulse that propagates along a laser beam propagation path terminating at a laser beam spot on the workpiece. The method is effective to move the laser beam spot across the structures along the linear pattern at a speed greater than the product of the PRF and the pitch to selectively irradiate selected ones of the structures with the laser without substantially degrading the desirable pulse properties.

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Seattle, WA, United States of America

Steve Stone