I guess the main confusion of defining this lens is probably the setting of depth/frequency. PwF}yxkI
lqX]'gu]\
The main fresnel lens types are: SnQ$
'(2G qX!
* Constant groove depth. &9o @x]) @
* Contant groove pitch types. umrRlF4M;
ed{z^!w4
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. @#VxjXW^
bRNE:))r_
Hope this helps!!