Principles of Interference

Abstract

The word ‘coherence’ describes the ability of radiation to produce interference phenomena and the notion of coherence is defined by the correlation properties between the various quantities of an optical field. The optical coherence is related to the various forms of the correlations of the random processes (Born and Wolf 1984; Mandel and Wolf and Wolf 1995). The interference phenomena stems from the principle of superposition, which states that the resultant displacement (at a particular point) produced by two or more waves is the vector sum of the displacements produced by each one of the disturbances. It reveals the correlations between light waves. The degree of correlation that exists between the fluctuations in two light waves determines the interference effects arising when the beams are superposed. The correlated fluctuation can be partially or completely coherent