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Difference between merit function operand value and coordinate in analyse's text file

  • 3 June 2022
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Hi,

I have to get the centroid coordinates from the huygens PSF analyse. At first, I tried to get the values from the text file itself, but it was taking way too much time for what I had to do. I decide to get the merit function operand value CEHX/CEHY instead, but the values from the text file and the ones I get from the merit function are slightly different. I was wondering why and if there was a way to correct that difference. 

Thank you !

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Best answer by MichaelH 3 June 2022, 17:18

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Hey Jesse,

There are a few extra settings between the Huygens PSF Analysis and the CEHX/CEHY; namely the Huygens PSF Analysis has:

  • Image Delta
  • Use Centroid

To get the same values between the Huygens PSF Analysis and the CEHX/CEHY, you will need to keep both of these values as their default, namely Image Delta = 0 and Use Centroid unchecked.  Although it’s counter-intuitive from the name, the Use Centroid box is more about centering the plot and the centroid this checkbox refers to is the geometric spot size centroid, not the Huygens PSF centroid:

 

Also, if you have Vignetting Factors set in your Field Data Editor, make sure you are not using a CVIG operand above your CEHX/CEHY in the MFE otherwise you’ll have a different rayset between the Huygens PSF Analysis and the Merit Function Editor.

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