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.

Typical laser diffraction experimental setup
Click to enlarge: Typical laser diffraction experimental setup

How Laser Diffraction Works

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-960 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.

Idealized scattering off a spherical particle
Idealized scattering off a spherical particle

Both the hardware and software required to make a particle size measurement have gone through many revisions in order to improve accuracy, precision, reliability, and ease of use. The LA-960 represents the tenth generation of HORIBA laser diffraction analyzers; each different and better than the last. Read on to discover what important factors go into making this measurement routine and trustworthy.

More Information about Laser Diffraction

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