Group fronts in PIM-NIM as well as PIM-PIM
This is how the group refracts positively (both in NIM and in PIM).
Note how the group front crosses the surface in such a way that
positive Snell's law is satsfied.
So this is the right group ray diagram with positive refraction for all
media, even for NIM. The standard ray diagrams on the right are all
For contact and comments, email to
© 2002 CEMD, University of Texas at Austin. All rights reserved.