I guess the main confusion of defining this lens is probably the setting of depth/frequency. i'7+
?YL
%IX)+
Lp`
The main fresnel lens types are: ](A2,F
9(U
s4~[GO6>
* Constant groove depth. \ l#eW
x
* Contant groove pitch types. n{FjFlX2=
W3:Fw6v
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. 2lCFE)
XzHR^^;u"*
Hope this helps!!