Light scattering by multi-layered ellipsoidal particles in the quasistatic approximation

The Rayleigh (RA) and Rayleigh-Gans approximations (RGA) are generalized in the form of the quasistatic approximation (QSA). The advantage of the QSA is most conspicuous for non-spherical scatterers. In this case, the RA, RGA etc are known to have a quickly decreasing range of applicability with growing particle asphericity, whereas the range of the QSA remains practically independent of the scatterer shape. In this paper we develop the QSA for multi-layered ellipsoids in the general case of non-confocal surfaces of layers. Our numerical results for layered ellipsoids show that the QSA is preferable to the RA (and RGA) if the ratio of the maximum to minimum dimensions of the outer (inner) boundary of the layer dominating the scattering process exceeds ∼ 3, which coincides well with the conclusion drawn earlier for homogeneous spheroids. We also introduce a special rule of the effective medium theory giving much more accurate results than the known ones for small layered ellipsoids.