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Interference and Diffraction 14.1 Superposition of Waves Consider a region in space where two or more waves pass through at the same time. According to the superposition principle, the net displacement is simply given by the vector or the algebraic sum of the individual displacements. Interference is the
Diffraction refers to what happens to a wave when it hits an obstacle. The key to understanding diffraction is a very simple observation first due to Huygens in 1678. Say a wave arrives at an opaque screen with a little hole in it.
Hyugens-Fresnel principle. If one perturbs a plane wavefront, the Huygens wavelets will no longer constructively interfere at all points in space. Adding the wavelets by physical optics explains why light can turn corners and create fringes around images of objects.
Diffraction describes the tendency for light to bend around corners. Huygens principle. All points on a wavefront can be considered as point sources for the production of secondary wavelets, and at a later time the new wavefront position is the envelope (or surface of tangency) to these secondary wavelets. Fresnel’s Addition.
1 Ιαν 2015 · We introduce here diffraction in general, as well as neutron and powder diffraction in particular as a tool to study the structure of condensed matter, crystalline solids in particular.
1 Principles of X-ray Diffraction. Diffraction effects are observed when electromagnetic radiation impinges on peri-odic structures with geometrical variations on the length scale of the wavelength of the radiation.
Diffraction by linear grating (row of atoms); difference of optical paths through neighbouring atoms. By putting h = 0, a solution of this is seen to be k = kl; that is,
