US 7,616,669 B2
	High energy pulse suppression method
Keith Grant, Beaverton, Oreg. (US); Steve Stone, Seattle, Wash. (US); and Brady Nilsen, Beaverton, Oreg. (US)
Assigned to Electro Scientific Industries, Inc., Portland, Oreg. (US)
Filed on Nov. 24, 2004, as Appl. No. 10/997,586.
Application 10/997586 is a continuation in part of application No. 10/611798, filed on Jun. 30, 2003, granted, now 6,947,454.
Prior Publication US 2005/0100062 A1, May 12, 2005
Int. Cl. H01S 3/11 (2006.01)

U.S. Cl. 372—10  [372/90; 372/26; 372/92]

26 Claims

1. A method of forming from laser pulses generated by a Q-switched laser cavity a composite stream of nonuniformly time-displaced laser pulses that include working laser output pulses having working pulse energy values and dummy laser output pulses having dummy pulse energy values, wherein the working laser output pulses are laser pulses whose propagation to a workpiece is permitted by a gating device in an unblocking state and wherein the dummy laser output pulses are laser pulses whose propagation to the workpiece is prevented by a gating device in a blocking state; at least some consecutive ones of the working laser output pulses being mutually uniformly time displaced from one another and having substantially constant working pulse energy values; and some of the dummy laser output pulses causing, for associated nearest successive ones of the working laser output pulses, variations of their working pulse energy values from the substantially constant working pulse energy values, comprising: determining effects of incomplete cavity energy discharge resulting from interaction of certain ones of the working laser output pulses and associated ones of the dummy laser output pulses on the variations from the working pulse energy values of the associated nearest successive ones of the working laser output pulses; introducing laser output pulse compensation in amounts sufficient to offset the effects of incomplete cavity energy discharge contributed by the dummy laser output pulses to limit within a preassigned operational tolerance the variations from the substantially constant working pulse energy values; and selectively gating the composite stream of nonuniformly time-displaced laser pulses to exclude the dummy laser output pulses and thereby provide a stream of nonuniformly time-displaced working laser output pulses having working pulse energy values with variations that are limited within the preassigned operational tolerance.