Use of Analytic Signals in Third- and Fourth-Order Coherence Functions

Abstract

In this paper complex forms of the third‐ and fourth‐order coherence functions are defined using analytic signals. The relations between the complex forms and the real forms are given in detail. It is shown how to use the complex forms in the solution of radiation problems. The quasimonochromatic approximation greatly simplifies the calculations and this simplification is discussed for radiation problems in terms of the complex forms. The paper concludes with a discussion of quasimonochromatic radiation from a modulated incoherent source representing, perhaps, a self‐luminous turbulent region.