Appeal No. 2001-0238
Application No. 08/859,020
11. An apparatus for machining metals and alloys,
comprising:
a solid state laser for producing a laser beam; and
means for directing said laser beam onto a workpiece
comprising material selected from a group consisting of metal and
alloy, wherein said laser beam comprises a plurality of laser
pulses, wherein said laser pulses have a pulse repetition rate
greater than 10 Hz and a wavelength in the range of 750 nm to
10.7 microns, wherein each said pulse of said plurality of laser
pulses has a pulse duration within the range of 10 femtoseconds
to 100 picoseconds and a focused irradiance of greater than 1012
W/cm2, wherein each pulse of said plurality of laser pulses
converts approximately greater than 0.1 micron to 1 micron of
material of said workpiece from a solid state to a plasma state,
wherein said material is removed from said workpiece by
hydrodynamic expansion of said plasma.
The Reference
Pronko et al. “Machining of sub-micron holes using a femtosecond
laser at 800 nm,” Optics Communications, Vol. 114, pages 106-110,
January 15, 1995. (Pronko).
The Rejection
Claims 1-11 are rejected under 35 U.S.C. § 103(a) as being
unpatentable over Pronko.
The Invention
The present invention is said to provide a method for laser
cutting/machining of metals and alloys which achieves high
machining speed with extreme precision, negligible heat affected
zone, and no modification to the material surrounding the kerf.
The method is accomplished by focusing a laser pulse of between
10 femtoseconds to 100 picoseconds onto a surface to produce an
ionized plazma while the material to a depth of approximately 1
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