Diffractions – A Historical Perspective

Diffraction is a phenomenon that is caused by medium features that are small compared to the wavelength of the wave. Sommerfeld defines diffraction as “any deviation of light rays from rectilinear paths which cannot be interpreted as reflection or refraction”. Landau and Lifshitz state that diffraction refers to phenomena which are the “consequence of deviations from geometrical optics”. In this paper we present a brief historical sketch of diffraction theory. We present original material from the key works of Grimaldi, Huygens, Young, Fresnel, Kirchhoff and others representing milestones in the development of the theory. The examples range from the early experiments by Grimaldi in the 1600’s to the seismic diffraction modelling of edge and tip waves.