I guess the main confusion of defining this lens is probably the setting of depth/frequency. 1 e]D=2y
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The main fresnel lens types are: e ^ ,IZ{
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* Constant groove depth. zXU
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* Contant groove pitch types. $N Mu
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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. {pA&Q{ ^
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Hope this helps!!
