Diffraction, Interference, Coherence

Abstract

In this chapter, we study different types of interference phenomena. Interference happens when two or more waves having a phase relation with one another fixed in time overlap in a region of space. We study Young’s two-slit experiment and then the coherence conditions, namely the conditions that must be satisfied for interference phenomena to be observable. After having introduced diffraction with Grimaldi’s discovery, we treat the phenomenon under Fraunhofer conditions in the important cases of the slit, the circular aperture, randomly distributed centers and the diffraction grating. Finally, we study the close relations between the physics of diffraction and the mathematics of the Fourier transform.