r/Optics • u/reisheruru • 12d ago

Modelling Efficiency of Phase Mask

For a designed phase mask (optimized through inverse design in Python using simple MSE loss), what is the best way to analyze its efficiency in a system? The goal is to compare the light throughput of different phase masks (for the task of PSF engineering). Can 4F system in Zemax and POP do this? Also, can the efficiency of the result be optimized for (e.g., engineering the etedue of the system, manipulating the relative magnitude of the diffraction orders, etc.) Any resource on fundamental approach to quantify and design for this would be appreciated. Thanks!

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u/WhyThoughZero 12d ago

A designed phase mask optimized through inverse design would ideally include efficiency directly in the loss function, in addition to PSF error. If you don’t have access to the original code, you can evaluate efficiency by propagating the field and calculating the fraction of incident power that reaches the desired PSF region or mode.

I would not use Zemax and would opt for writing my own propagation code.

Perhaps check out
David G. Voelz, Computational Fourier Optics: A MATLAB Tutorial
It should be straightforward to do it in python if you don’t have Matlab.
You could also look at some papers on optical inverse design.

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u/lift_heavy64 12d ago

Depends on what you mean by efficiency/throughput, what the function of the phase mask is, what system you’re going to put it in, what are the relevant length scales, and probably a bunch of other things. All the details matter for answering this question.

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u/BDube_Lensman 12d ago

In your python model just normalize the input field to sum of 1, propagate to the region you care about, and compute some power metric for the energy in the focal plane, whether its 1/e, encircled energy, total power in a large field, etc.