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.


