Patent ID: 7884303

Claim:
A surface heating mechanism for melting a layer of a workpiece, said mechanism comprising: a pulsed XeF laser operating at or above 3000 Hz and producing a laser output light pulse beam; an optical system including a field stop intermediate the laser and the workpiece, said optical system narrowing the laser output light pulse beam to a width (w) in a short axis of the laser output light pulse beam and expanding the laser output light pulse beam to a length (l) in a long axis of the beam; wherein an aspect ratio (l/w) of said beam is greater than about 36,000; the workpiece comprising a layer to be heated; and a high average power in the laser output light pulse beam as delivered to the workpiece. wherein the system projects adjacent peaks of the nominal XeF spectrum to improve the overall depth of focus through the separate center wavelengths of each respective adjacent peak having a different focal plane at the workpiece.