Huygens principle at the boundary of a volume

[Ulises]

Hi all, I have the next dude:

To utilize the Huygens principle at the boundary of a volume, do we need to know precisely material properties inside the volume?

Thanks!

 

[RUber]

As far as I understand, Huygen's principle is outward looking. So the benefit is that you don't need to know anything about inside the volume, just the fields at the boundary.

 

[tech99]

As far as I understand, Huygen's principle is outward looking. So the benefit is that you don't need to know anything about inside the volume, just the fields at the boundary.

I think you first need to know the shape and position the wavefront before the secondary sources can be drawn. This probably means waiting until the beam emerges from the volume.