Dear,   
   I wonder if there is someone with a copy of a Bausch & Lomb grating catalogue.   
   PDF is fine too. Later the company name changed to "Richardson Grating", now   
   part of Newport.   
   I own an old (concave) grating and do not know the mechanical setup. Further   
   grating efficiency range would be helpful too.   
      
   Sure, I can easily identify main orders (-2, -1, 0, 1, 2), the focal length, I   
   guess it is a 1:1 projection - but I miss values for angles in order to   
   minimize aberations.   
      
   In my case the grating has the catalogue number 33-52-23-71.   
      
   cheers   
   Helge   
      
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