Ex parte WAGNER - Page 5

              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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