Average number and probability distribution of caustics in randomly inhomogeneous medium and behind a random phase screen

Formulas are derived for the average cross-sectional caustic density and the probability density of the distances to caustics behind a random phase screen. The constancy of the average number of caustics at great distances behind the screen as the probability density approaches zero is explained.Nizhny Novgorod Architecture and Construction Academy. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 4, pp. 471–478, April, 1994.