I am tolerancing a system to achieve certain MTF requirement at 840 nm, which is my primary wavelength. I would like to use FFT MTF, since my system has a central obscuration so diffraction MTF is quite lower than geometric MTF. But it seems that Zemax only allows tolerancing either for diffraction or geometric. Is there any way to tolerance for FFT MTF? If not, which one would be more convenient to use?
Thanks in advance,