Vol. 6, issue 11, article # 6

Abstract:

Aperture averaging functions experimentally measured for spherical waves reflected from a specular disc and a two—dimensional matrix of corner—cube reflectors are analyzed for strong intensity fluctuations. In the case of the specularly reflecting disc the values of the aperture averaging function for small receiving aperture are less than that for forward propagation and in comparison with the values calculated by the asymptotic theory of saturated fluctuations taking into account the inner scale of turbulence. When the size of the receiving aperture considerably exceeds the radius of spatial coherence of fluctuations, the averaging function G(R) is close to the dependence G(R) ~ R^-2 that corresponds to the summation of the uncorrelated wave intensity fluctuations over the receiving aperture. In the case of reflection from the matrix of corner—cube reflectors the function G(R) has two scales. Fast decrease of the intensity fluctuations occurs on the aperture whose size is equal to the diffraction size of the corner—cube. Slow decrease of the fluctuations for large receiving apertures (saturation of averaging function) is caused by fluctuations of the flux across the aperture of the corner—cube matrix.