I guess the main confusion of defining this lens is probably the setting of depth/frequency. f(C0&"4e
-R8RAwsLG
The main fresnel lens types are: QO
k%Q$^G
78Gvc~j
* Constant groove depth. \i&yR]LF
* Contant groove pitch types. ;EJ6C#}
>7
l^vq'<kI
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. |fA[s7)
v|"{x&I.
Hope this helps!!