The laser diffraction method is widely used to measure particle size distributions. It is generally accepted
that the scattering angle becomes smaller and the angles to the location of the main peak of scattered
energy distributions in laser diffraction instruments shift to smaller values with increasing particle size.
This specific principle forms the foundation of the laser diffraction method. However, this principle is
not entirely correct for non-absorbing particles in certain size ranges and these particle size ranges are
called anomalous size ranges. Here, we derive the analytical formulae for the bounds of the anomalous
size ranges and discuss the influence of the width of the size segments on the signature of the Mie
scattering kernel. This anomalous signature of the Mie scattering kernel will result in an indetermination
of the particle size distribution when measured by laser diffraction instruments in the anomalous size
ranges. By using the singular-value decomposition method we interpret the mechanism of occurrence of
this indetermination in detail and then validate its existence by using inversion simulations.