We begin reminding some basic concepts about stochastic functions (Wiener-Khinchin theorem) and about linear systems (Green's function, transfer function), just to define the symbols we use.
Then we describe some old experiments which illustrate basic concepts related to white light interference: the Fizeau spectral beating experiment, channeled spectra, and the experiments of Alford and Gold and of Delisle and Cielo.
As an illustration of applications of these concepts, we indicate two fields: reflectometry and multiplexing.
