Measurements to estimate the spatial coherence of the electroluminescence signal from a commercial LED and upconverted photoluminescence signal from doped NaGdF₄ nanoparticles were done using Young's double slit setup. Experiments were performed with various slit sizes and the visibility of the interference fringes was observed. Part of the thesis work also involved examining the feasibility of using a spatial light modulator as an optical element in diffraction and interference experiments.
The mathematical representation of each of the four interference laws of Fresnel and Arago is presented. Each of the laws is characterized by a unique Stokes vector. These vectors are arrived at by a matrix analysis of the, interference experiments of Fresnel and Arago in which only polarizers are used. The historical motivation that led Stokes to introduce the parameters that now bear his name is noted. The similarity in the approach taken by Stokes to represent the fundamental properties of the classical optical field in terms of observables is compared with Heisenberg's approach to the formulation of quantum mechanics. The mathematical statements that characterize unpolarized light are developed. These statements are then used to determine the Stokes vectors that describe each of the four interference laws of Fresnel and Arago. In a final section of the paper the mathematical apparatus developed here is used to describe Young's interference experiment with unpolarized light.