These effects can be modelled using the Huygens–Fresnel principle Huygens postulated that every point on a wavefront acts as a source of spherical secondary wavelets and the sum of these secondary wavelets determines the form of the proceeding wave at any subsequent time, while Fresnel developed an equation using the Huygens wavelets together with the principle of superposition of waves, which models these diffraction effects quite well. When a beam of light is partly blocked by an obstacle, some of the light is scattered around the object, light and dark bands are often seen at the edge of the shadow – this effect is known as diffraction. This is due to the superposition, or interference, of different parts of a wave that travels to the observer by different paths.Example of far field (Fraunhofer) diffraction for a few aperture shapes. If the obstructing object provides multiple, closely spaced openings, a complex pattern of varying intensity can result. While diffraction occurs whenever propagating waves encounter such changes, its effects are generally most pronounced for waves whose wavelength is roughly similar to the dimensions of the diffracting objects. He suggested that when there are only a few sources, say two, we call it interference, as in Young's slits, but with a large number of sources, the process be labelled diffraction. Italian scientist Francesco Maria Grimaldi coined the word "diffraction" and was the first to record accurate observations of the phenomenon in 1665. As physical objects have wave-like properties, diffraction also occurs with matter and can be studied according to the principles of quantum mechanics. Diffraction occurs with all waves, including sound waves, water waves, and electromagnetic waves such as visible light, X-rays and radio waves. Similar effects occur when a light wave travels through a medium with a varying refractive index, or a sound wave travels through one with varying acoustic impedance. ![]() In classical physics, the diffraction phenomenon is described as the apparent bending of waves around small obstacles and the spreading out of waves past small openings. In this case, when the waves pass through the gap they become semi-circular.įreebase Rate this definition: 5.0 / 1 voteĭiffraction refers to various phenomena which occur when a wave encounters an obstacle. Diffraction is greatest when the size of the gap is similar to the wavelength of the wave. Furthermore, quantum mechanics also demonstrates that matter possesses wave-like properties, and hence, undergoes diffraction (which is measurable at subatomic to molecular levels).The amount of diffraction depends on the size of the gap. These effects also occur when a light wave travels through a medium with a varying refractive index, or when a sound wave travels through a medium with varying acoustic impedance – all waves diffract, including gravitational waves, water waves, and other electromagnetic waves such as X-rays and radio waves. ![]() If there are multiple, closely spaced openings (e.g., a diffraction grating), a complex pattern of varying intensity can result. This is due to the addition, or interference, of different points on the wavefront (or, equivalently, each wavelet) that travel by paths of different lengths to the registering surface. The characteristic bending pattern is most pronounced when a wave from a coherent source (such as a laser) encounters a slit/aperture that is comparable in size to its wavelength, as shown in the inserted image. In classical physics, the diffraction phenomenon is described by the Huygens–Fresnel principle that treats each point in a propagating wavefront as a collection of individual spherical wavelets. ![]() Italian scientist Francesco Maria Grimaldi coined the word diffraction and was the first to record accurate observations of the phenomenon in 1660. The diffracting object or aperture effectively becomes a secondary source of the propagating wave. Wikipedia Rate this definition: 0.0 / 0 votesĭiffraction is defined as the interference or bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture.
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