Kazuma Yamashita

Dear Robertson,

Thank you so much for your helpful reply. I did not use any script commands; I just calculated the far fields from GUI with default settings (so a semicircle of 1 m diameter is located underneath the monitor). It was weired for me that refraction at a smooth curved surface, rather than diffraction generated such interference fringes.

And I also noticed that when there is no gap between the sphere and the periodic boundary condition (PBC being in contact with the sphere), the fringes were significantly suppressed and I obtained a very smooth angular profile (image attached). This result agrees with my intuition as the optics does not contain diffraction, so why did I obtain the fringes when there is a gap? Possibly the small gap at PBC worked as an opening that causes diffraction? Or is it due to far field artifacts or PBC?

Best regards,No gap