Orientation-averaged spectra of oblate (upper panel) and prolate (lower panel) spheroidal particles with different axis ratios and equivalent sphere radius 1 μm. Solid lines: average of the 9 relevant FDTD spectra of the start- and endposition of each setup. Dotted lines: average of the according spectra of the isotropic materials. Thin grey lines: 1/3–2/3-approximation of the orientation-averaged spectra calculated with the T-matrix implementation of Somerville et al. (2016). For moderate axis ratios, the average of the nine spectra is a convenient alternative for an orientation-averaged spectrum. Thanks to this, the effects of the material anisotropy can be identified in the averaged FDTD spectra.