From: mgashaw@gmail.com   
      
   Hi all,   
      
   I would like to write a routine (either in c or matlab) which can be used to   
   collapse a given conic or aspheric surface to Fresnel zones, which is   
   basically designing a Fresnel lens from a given lens entity(surface). Fresnel   
   Lens(FL) which has prismatic    
   facets is easy to implement.But in this case the facets have to be   
   conic(aspheric) and different ways of realizing the FL is possible like fixed   
   sag per zone and fixed zone spacing.That is the general goal. My problem is   
   breaking down this problem into    
   smaller pieces to make it easy for coding. Therefore, my question is : what   
   are the basic blocks that my code needs to have to construct a FL from a given   
   surface? A sample code would be appreciated.   
      
   Thanks,   
   Gash   
      
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