Appeal No. 97-1107 Page 11
Application No. 08/047,512
We conclude that the examiner has established a prima facie case of obviousness with respect
to the subject matter of claims 10, 15-21, 23, 25 and 26, which has not been sufficiently rebutted by
appellant.
Obviousness of Claim 27
Claim 27 requires that the gas analysis cell have an internal tube fixed to the inlet that extends
into the cell body. As Barnes does not teach an internal tube at the inlet, the examiner has rejected
claim 27 over Barnes in combination with Rossiter, optionally Lew and additionally Nelson. As pointed
out by the examiner in the rejection (Answer, page 7), Nelson teaches a gas inlet 87 that extends into
the cell body. The extended inlet 87 is positioned to direct the gas in a manner that results in a
reduction in the time required to achieve gas purge. We note that the gas cell body is designed to
conform to a conical optical beam. We agree with the examiner that it would have been obvious to one
of ordinary skill in the art at the time of the invention to provide the cell of Barnes with a tube extending
into the cell interior as taught by Nelson so that the gas could be admitted at a tangent and thus the gas
purging time could be reduced.
The fact that Nelson teaches a conical cell and admitting the gas at the diverging end and
purging the gas at the converging end does not teach away from using an extending inlet in Barnes to
create a flow of gas that results in faster purge. One of ordinary skill in the art would have reasonably
expected that gas flow would have improved at least up to the necked down area of a converging-
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