Scattering from objects immersed in a diffusive medium

The disturbance of the transmission of light through a diffusive medium due to an object hidden in it can be expressed in terms of an effective charge and dipole moment. In the mesoscopic regime, beyond the diffusion approximation, we calculate this effective charge and dipole moment. Various objects are considered: a single point scatterer, a localised density of such scatterers and a small sphere.