Averaging effect of a receiving aperture in the case of reflection in a turbulent atmosphere

The approximate method of smooth perturbations is used to calculate the averaging function and time spectra of fluctuations of a light flux through an annular aperture in a path with reflection. It is shown that the averaging effect and the spectra are only slightly different for the direct and reflected signals. Simultaneous measurement of the averaging effect and time spectra revealed, on the one hand, a good agreement with the theoretical averaging function but, on the other, showed only a qualitative agreement with the calculated spectrum of fluctuations of the light flux indicating the need to allow for fluctuations of the wind velocity and direction.