- A series of detectors which are used to measure the light pattern produced
over a wide range of angles.
In laser diffraction, particle size distributions are calculated by comparing a sample’s
scattering pattern with an appropriate optical model using a mathematical
inversion process. Traditionally two different models are used: The Fraunhofer
Approximation and Mie Theory.
Mie Theory provides the best solution for the calculation of particle size distributions
from light scattering data and is based on Maxwell’s electromagnetic field
equations. It predicts scattering intensities for all particles, small or large, transparent
or opaque with the following assumptions:
- The particles being measured are spherical
- The suspension is dilute, such as the scattered light is measured before it is
re-scattered by other particles. - The optical properties of the particles and the medium surrounding them is
known - The particles are homogeneous