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I have a Gaussian to flattop beam shaper, the layout is attached, the website does not alow me to upload Zemax file. The POP irradiance plot shows strange not-rotational-symmetric wide fringes, although the Guassian beam data used in the layout and POP are exactly the same and the system is rotational symmetric. If converting this system is to NSC, there is no such wide fringes. Can someone explain this? Thanks.

 

Hi,

This is called aliasing (you see aliases -- copies -- of the pattern). The resolution at an earlier position in the system is too coarse or the array lateral extent too small (depends on the propagation used). In general, you need to increase sampling or size in prior planes until there are no such weird artefacts.

 

 


Hi Ray: 

Thank you for help. I increase the sampling from 1024 to 4096, the aliasing is gone, that is great.


To check for aliasing, it is best to inspect the phase plot. There is an excellent three part article on POP by Erin Elliott Here.

Kind regards,

David
 

 


Thank you David for the reply


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