Translations:Analogy/46/en

Fresnel resolved that difficulty with his introduction of the interference principle. The corresponding Huygens-Fresnel principle now states that each unobstructed point of a wavefront at a given instant serves as a source of spherical secondary wavelets (of the same spectral content as the primary wave). The amplitude of the wave at any position beyond that point is then the superposition of all such wavelets (considering their amplitudes and relative phases).