Static light scattering illustrated with two illustrations utilizing particle sizing designs:

With static light scattering (often referred to as laser diffraction) compared to dynamic light scattering, not the timely variation, but the angle dependency of the scattering intensity for the particle size determination is utilized.

In order to determine the size of particles, they are irradiated with a laser beam. Through the scattering of the laser light behind the sample a characteristic, ring-shaped intensity distribution evolves, which is measured with a specially shaped detector. From the distance of these rings (respectively the belonging scattering angle) is the particle size calculated: Large particles generate close neighbouring rings (small scattering angles), small particles generate rings wide apart (large scattering angles).

For the calculation of the particle size respectively the particle size distribution either the Fraunhofer theory (large particles) or the Mie theory (small and large particles) are utilized.

N.B.: With static light scattering the sample material is mostly in motion and flows, respectively flies through the measurement cell. Therefore the term “static” does not refer to the sample, but to the (in comparison) static intensity distribution. Incidentally, the size of the particle speed is no issue for static light scattering.