Laser Diffraction Technology

Light scattering has long been used to investigate the size of various objects. Gustav Mie (he of the Mie Scattering Theory) studied gold nanoparticles like those in the image below as part of his doctoral thesis. Previously confined to custom-built setups in labs, several innovations took laser diffraction from the darkroom to research labs and production floors across the world.

So how does laser diffraction work? At its very most basic, laser diffraction is about the relationship between particle size and the angle and intensity of scattered light. Light scatters more intensely and at smaller angles off of large particles than small particles. Every analyzer, from the very first commercial prototype to the state of the art LA-950 utilizes this principle. In fact, the analyzer itself does not measure particle size -- it measures the angle and intensity of light scattered from the particles in your sample. That information is then passed to an algorithm designed to use Mie Scattering Theory which transforms the scattered light data into particle size information.