# Huygens' principle and phase shift

1. May 7, 2009

### paweld

I wonder why the amplitude of Huygens' wavelet is equal to the amplitude of incident wave multimpled by $$i / \lambda$$. I found this formula in 'Modern Optics' by Guenther p. 335 unfortunately without proof. Has anyone seen the derivation of this fact.

Could you recomend me some good books in optics about wave nature of light.

2. May 12, 2009

### |squeezed>

Without knowing the formula that you 're referring to, i can tell that terms like these usually appear from the expansion of the point source (exponent of ik|r-r'|, sometimes referred as Huygens elementary wave) over large distances.

The absolute, classic reference for wave phenomena in optics is Born & Wolf. You can find almost everything there. The figures are very nice and clear.