Calibration curves calculated by us using Mie theory for different scattering and integration angles are shown in Fig. 22.4. As we can see, especially in the case of forward and backward scattering, the relation between the size and the scattered intensity in certain size ranges is not uniform, the long-period oscillations for back scattering being pronounced in the 0.4–1 micrometre range and for forward scattering in the 1–3 micrometre range.In case of perpendicular scattering shorter oscillations are pronounced in the 2–5 micron range, but if we measure the size distribution, this geometry is even better. In this case the dependence on the refractive index of the particles is also less pronounced.