Small-angle scattering by optically "soft" spherical particles

The small-angle and integrated indicatrices of light scattering by a soft s pherical particle are studied as functions of the phase shift. Simple analy tic expressions are obtained for these functions in the Wentzel-Kramers-Bri llouin approximation, which relate their amplitude and angular structure to the scattering efficiency and also to analogous expressions for Fraunhofer diffraction. The validity of the expressions obtained is proved numericall y with the help of the Mie theory.