Reply To: scattering calculation with gaussian beam in FDTD

[Guilin Sun]

NA beam is diffraction-limited vectorial fields. High NA beam profile will have obvious diffraction pattern, which is correct: https://optics.ansys.com/hc/en-us/articles/360034382854-Plane-wave-and-beam-source-Simulation-object

For low NA, the bem size is large, and al may need better PML performance. Please use larger simulation spans and more PML layers and make sure source is wide enough not cliping the field. You can use log scale to check the intensity at the edge.