ABSTRACT
In this chapter, a special kind of superposition is explored. It is the interference of light waves subject to particular conditions of wavelength, amplitude, phase, and coherence. Most important among these is the coherence of the interfering waves and direction of oscillation of their electric fields; the former is so critical for the sustainability of the interference, and the latter makes the analysis simpler, enabling better understanding of the properties of the resulting interference. We treat here a variety of methods followed in understanding interference. For interference of two waves to happen, a difference in phase that remains constant between them is fundamental. Interference may happen between two beams or multiple beams. Young’s double-slit setup that provides a two-beam interference was the earliest experiment used to produce an interference pattern. It generated more interest and helped to empirically support the wave nature of light, which was established theoretically several decades later by Maxwell in his electromagnetic theory of light.
