Question

Tolerancing for MTF

  • 4 August 2022
  • 2 replies
  • 23 views

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,

Alba


2 replies

Userlevel 6
Badge +3

The diffraction MTF is the FFT MTF, so just use that.

Userlevel 1
Badge

Hi Alba, 

As Mark says, the FFT MTF is one of the diffraction MTF calculations in OpticStudio. To elaborate on that a bit more, we have three MTF options:

  • Geometric MTF
  • FFT MTF
  • Huygen’s MTF

The FFT and Huygen’s MTFs use different diffraction propagation algorithms, and you can see a good description of them here: Methods for analyzing MTF in OpticStudio. Any of these could be used during your tolerance analysis, based on the system specification. 

Let us know if you have any other questions here!

Cheers,

Nick

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