Appeal No. 2001-0238
Application No. 08/859,020
of 1012 W/cm2 to speed machining or form deeper features as the
material removal rate is proportionate to the beam energy. (Paper
#5, page 3, lines 17 – 27).
The appellants counter that the claimed method results in
the conversion of workpiece to plasma for any pulse duration less
than 100 picoseconds, contrary to the logic that it would be
necessary to increase the pulse width to produce an increase in
material removal (Appeal Brief, page 12, lines 1 – 12). The
reasoning is that Pronko is acting in a low power range
(approximately 1010-1011 W/cm2) and only converting material to
vapor, not plasma. According to the appellants, only a
negligible additional amount of material can be removed by
increasing the pulse width in the fully ionized plasma realm of
1012 W/cm2, as the additional energy simply goes into the plasma.
(Appeal Brief, page 12, line 13 – page 13, line 8).
Claims 1 and 10 contain, in terms of beam power, the
limitation that each pulse 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. Claims
2 and 11 require a focused irradiance of 1012 W/cm2.
We find that the Pronko reference discloses the formation of
plasma (page 107, column 1, line 4) during the laser oblation
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