|
In optics, the Fraunhofer diffraction equation is used to model the diffraction of waves when the diffraction pattern is viewed at a long distance from the diffracting object, and also when it is viewed at the focal plane of an imaging lens.〔Born & Wolf, 1999, p 427.〕〔Jenkins & White, 1957, p 288〕 The equation was named in honour of Joseph von Fraunhofer although he was not actually involved in the development of the theory.〔http://scienceworld.wolfram.com/biography/Fraunhofer.html〕 This article gives the equation in various mathematical forms, and provides detailed calculations of the Fraunhofer diffraction pattern for several different forms of diffracting apertures. A qualitative discussion of Fraunhofer diffraction can be found elsewhere. ==Fraunhofer diffraction equation== When a beam of light is partly blocked by an obstacle, some of the light is scattered around the object, and light and dark bands are often seen at the edge of the shadow – this effect is known as diffraction.〔Heavens & Ditchburn, 1996, p 62〕 The Kirchhoff diffraction equation provides an expression, derived from the wave equation, which describes the wave diffracted by an aperture; analytical solutions to this equation are not available for most configurations.〔Born & Wolf, 2002, p 425〕 The Fraunhofer diffraction equation is an approximation which can be applied when the diffracted wave is observed in the far field, and also when a lens is used to focus the diffracted light; in many instances, a simple analytical solution is available to the Fraunhofer equation – several of these are derived below. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Fraunhofer diffraction (mathematics)」の詳細全文を読む スポンサード リンク
|