I guess the main confusion of defining this lens is probably the setting of depth/frequency. ! xM=7Q
k
{f/]K GGk
The main fresnel lens types are: KKk~vwW
u\ 7Y_`8
* Constant groove depth. 1v:Ql\^cT
* Contant groove pitch types. T"htWo{v>
;5;>f)diS
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. &i3SB[|
|e!Y
C iU
Hope this helps!!