From: pcdhSpamMeSenseless@electrooptical.net   
      
   On 11/27/2013 10:06 AM, Gash M wrote:   
   > On Wednesday, November 27, 2013 3:39:38 PM UTC+1, Helpful person wrote:   
   >> On Wednesday, November 27, 2013 8:54:35 AM UTC-5, Gash M wrote:   
   >>   
   >>> 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   
   >>   
   >>   
   >>   
   >> I hope you do realize that collapsing a curved   
   >>   
   >> surface to a flat Fresnel will result in different   
   >>   
   >> aberrations.   
   >>   
   >>   
   >>   
   > Thanks for the reply.You are right.But the orientation of the grooves for   
   different applications matters. In my case,I want the FL for collimation   
   purpose; so the groove out orientation is preferred.Moreover,since the   
   application is for illumination    
   aberration is not much a concern here.I know how to model conventional FL in   
   commercial products like Zemax.My interest is to write a code which can   
   collapse a given surface to Fresnel zones. Could you give me some guidance how   
   to start?   
   >   
   > Thanks,   
   >   
   > gash   
   >   
      
   It's a poorly posed problem.  You can't just take onion slices of the   
   surface and arrange them on a plane, because that will completely   
   destroy the imaging properties of the lens--each ring will produce a   
   focus at a different Z position.  (I know that there are misleading   
   pictures, in some optics books that shall not be named, that make it   
   look like that's the procedure, but it isn't.)   
      
   You have to adjust the power of each ring to focus at the same place.   
      
   (And of course, the behaviour with field angle is also completely   
   different--Fresnels fall apart completely as the field angle goes up.)   
      
   Cheers   
      
   Phil Hobbs   
      
   --   
   Dr Philip C D Hobbs   
   Principal Consultant   
   ElectroOptical Innovations LLC   
   Optics, Electro-optics, Photonics, Analog Electronics   
      
   160 North State Road #203   
   Briarcliff Manor NY 10510   
      
   hobbs at electrooptical dot net   
   http://electrooptical.net   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)