Dear Fu-Kwun,

When I set cta= 45.0 and index of refraction = 1.45 and let the simulation run for a while, some additional lines start to appear on the medium in the right hand side (please see screeshot below). The simulation will come to a stop soon after this. Is this an error? Thanks.

[img]http://i171.photobucket.com/albums/u305/tanghb2/Physics_teaching/Refract.gif[/img]