I was hoping to ask a question about Huygens' principle, which I am using to understand diffraction and reflection. I have seen videos and websites like these that explain why Huygen's principle leads to the law of reflection: https://www.youtube.com/watch?v=N3levs4TzTA https://www.compadre.org/nexusph/course/How_Huygens_gets_reflection_and_refraction_(technical)
These resources appear to examine isolated points on the reflective surface, so I will do that too below.
I am struggling with one thing. Huygens' principle says that the wavefront can be modeled as a bunch of spherical wavelets. According to the resources, when the wavefront encounters a reflective point, the point begins to emanate wavelets.
However, supposing this reflective point did not exist, it seems like wavelets would already have been emanating from that location, as wavelets emanate from all points on the wavefront. I thought about if there was a difference in phase from the wavelets generated from the reflective point, and the wavelets at the wavefront, but they appear to have the same phase.
In Huygens' model, then, is the reflective point just treated as a 'point source' of wavelets, whose phase is the same as the incident wave?
If this is the case, it seems like this reflective point is just the opposite of an 'absorptive' point. The reflective point increases the energy of the wavelets that it touches on the wavefront, while the absorptive point decreases the energy of the wavelets that it touches on the wavefront.