Huygens MTF


I am plotting different MTFs by shifting the object position in ZEMAX. However, this MTFs are the magnitude of OTF and doesn’t account the phase changes (e.g phase reversal/ contrast reversal) in the OTF. Is this enough to judge the performance of the imaging system? or is there any trick to consider if there is a phase change?



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Perhaps if there’s a cusp (singularity) in the MTF that can give you an indication that there has been a contrast reversal. However, there can be a contrast reversal without cusps so this method can’t be used to rule out if contrast reversal is happening or not. There’s an example in this Wikipedia article:

In the Wikipedia figure, whenever the OTF changes sign, there’s a cusp in the MTF.

Take care,



@David.Nguyen Thank you a lot!