Allow me to repost  here for depth/frequency setting B"
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The main fresnel lens types are: 3,EtyJ3[Bh  
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    * Constant groove depth.  el\xMe^SY  
    * Contant groove pitch types.  )3 R5cq  
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So if your depth is fixed you will define +ve value in the cell and to specify the "height" or "depth" of each groove feature. If the frequency of the groove is fixed then you use -ve value. Say putting down - 5 this implies that there are 5 grooves with a unit length.  -?l`LbD  
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For radius, this is the curvature of the base surface. If you define one such lens and chaneg the radius and you shall see what it means. A graphic tells lounder than words. Rn`DUYg  
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For conic: check conic section using Wikipedia and you should see what conic constant means. ZuZCIqN  
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