Anisotropy of weak light scattering in thin opal films

The forward and backward light scattering that accompanied the almost ballistic light propagation in opal-based three-dimensional photonic crystal (PhC) has been experimentally studied. The light path memory and the high anisotropy of scattering have been associated with low-order scattering at large-scale crystal defects. The strong backscattered light intensity has been linked to the uncoupled light at a PhC surface. The exponent of power-law approximation of angle diagrams of the scattered light intensity has been suggested as a measure of the scattering anisotropy. The scattering anisotropy spectra have demonstrated that in a vicinity to the first photonic bandgap, the lower directionality of the forward scattering is complemented by the higher directionality of the backward scattering

Time-dependent angularly averaged inverse transport

This paper concerns the reconstruction of the absorption and scattering parameters in a time-dependent linear transport equation from knowledge of angularly averaged measurements performed at the boundary of a domain of interest. We show that the absorption coefficient and the spatial component of the scattering coefficient are uniquely determined by such measurements. We obtain stability results on the reconstruction of the absorption and scattering parameters with respect to the measured albedo operator. The stability results are obtained by a precise decomposition of the measurements into components with different singular behavior in the time domain