Huygen's wave theory
From The Glossary of Digital Photography
Also known as Huygen's Principle. First developed in 1678, the theory explains, among other things, why waves do not diffuse. It also was used to derive the laws of refraction and reflection. Later, it was expanded into the Huygens-Fresnel Principle, a method of analyzing wave propagation in a way that better explains diffraction events. The latter principle is named after Dutch physicist Christiaan Huygens and French physicist Augustin-Jean Fresnel. See also diffusion; Diffraction; refraction of light; reflection.
