I guess the main confusion of defining this lens is probably the setting of depth/frequency. L?[NXLn+
}a=<Gl|I;w
The main fresnel lens types are: SEf:u
5X8GR5P
* Constant groove depth. 4$HU=]b6Tf
* Contant groove pitch types. ED0Vlw+1
\U(;%V
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. pi/Jto25z
l+%2kR
Hope this helps!!