Hi,

Here is my very simple setup

and its spot diagram, which is smaller that Airy Radius, so I wanted to investigate PSF further using FFT PSF

but I don’t get any image, just black window

After that, Zemax is slowing down, stopped work and closed. When open Zemax again,  I am getting this message

I have tried with other file ( but with similar simulations) it is happening again - I am getting black screen for FFT PSF and Zemax is down. I am sure my laptop has enough RAMs to accommodate Zemax. 

Regards,

Marzanna