From: jsavard@ecn.ab.ca   
      
   Here's a reference to what Nikon is doing...   
      
   https://www.osapublishing.org/josa/abstract.cfm?uri=josa-51-1-17   
      
   ...at least, one web page, with an incorrect link, claimed that a 1961 paper   
   related to Nikon's use of phase Fresnel lenses. So this might be it.   
      
   John Savard   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)