Statistical radiometry


  • William H. Carter


This paper reviews developments in recent research on the connections between classical radiometry and the modern theory of partial coherence. This research addresses some important questions such as, why does the classical theory appear to give correct results for electromagnetic radiation from thermal sources, and how can the theory be modified to apply to radiation from nonthermal sources? The following specific facts are explained. The far field radiation pattern from a localized source distribution generally depends on the coherence properties of the source and not simply on its emittance. Classical radiometry applies to thermal radiation not because this radiation is incoherent but rather because it is partially coherent in a particular manner. Also, some quantities defined in classical radiometry have physical meaning for an electromagnetic field, and some do not.