There are many techniques available to measure the particle-size distribution of powders or droplets. The wide size range, from nanometers to millimeters, of particulate products, however, cannot be analyzed using a single measurement principle only. While in history mainly methods using mechanical, aerodynamic or hydrodynamic properties for discrimination and particle sizing have been used, today methods basing on the interaction of the particles with electromagnetic waves (mainly light), ultra-sound, or electric fields dominate.
