The spatial structure of average radiation intensity behind a phase screen including one-dimensional regular and two-dimensional random inhomogeneities is studied. The conditions are formulated, under which the intensity distribution averaged over an ensemble and over a receiver's aperture coincide, as well as the conditions, under which the radiative transfer equation is applicable to calculation of the average intensity distribution. Ill-posedness of the inverse problem is discussed. Restoration of a regular phase distribution on a screen from measurements of the average light intensity in a multipath region is shown to be impossible.