Appeal No. 1997-1899
Application No. 08/407,145
Referring to FIG. 2, there is shown a filter arrangement which can be
employed and included in each housing as 16 and 17 to provide night time
simulation during a daytime operation.
The filter shown includes a first polarizing plate 20, a second
polarizing plate 21 and a third polarizing plate 22. A fourth plate 24 is shown
and is positioned in the optical path as well. The plate 24 is a glass plate
which operates as a blue-green filter. The filter compensates for deficiencies
in the infrared transmission characteristics of the polaroid plates 20, 21 and
22 to avoid a contrast reversal effect. Essentially, contrast reversal is the
effect of the high reflectivity in the near infrared of most green foilage which
causes the foilage to appear white when viewed through the goggles.
Appellant argues that the polarization plates are not frequency/wavelength tunable
as required by the language of the claim 1. (See reply brief at pages 2-4.) We agree with
appellant. Furthermore, the polarization plates merely produce (plane) polarized light
which is further limited through the interaction of the three plates to limit the quantity of light
passing through the plates to the filter. The variation in the light is in the quantity rather than
the frequency/wavelength of the light which is varied.
Appellant argues that the examiner has not provided a nexus for the combination of
the tunable filter of Gunning III with the training aid of Burbo. (See brief at pages 5-10 and
reply brief at page 5.) We agree with appellant. In light of the deficiencies discussed
above, the examiner has not provided a convincing line of reasoning why it would have
been obvious to one of ordinary skill in the art at the time of the invention to incorporate a
wavelength-tunable filter into the training aid as taught by Burbo.
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