The Nicomp 380 Submicron Particle Size Analyzer uses Dynamic Light Scattering (DLS) to obtain the particle size distribution for samples with particles ranging from 1 nm to 5 microns. Through the use of the proprietary Nicomp analysis algortihm, the 380 is able to analyze complex multi-modal distributions with the highest resolution and reproducibility available.

Dynamic Light Scattering (DLS) also known as Photon Correlation Spectroscopy (PCS) works by first measuring the scattered light intensity at one angle. The intensity of light scattered in a particular direction by dispersed particles tends to periodically change with time. These fluctuations in the intensity versus time profile are caused by the constant changing of particle positions brought on by Brownian motion. DLS instruments obtain, from the intensity versus time profile, a correlation function. This exponentially decaying correlation function is analyzed for characteristic decay times, which are related to diffusion coefficients and then by the Stokes-Einstein equation, to a particle radius.

DLS has several advantages over other laser light scattering technologies available today. First, it is an absolute measurement, where knowledge of the composition of the suspended particles is not needed. This can be helpful if the optical properties of the suspended particles are not known or if the suspension is made up of particles with different optical properties. Second, DLS can size particles down to 1 nm, which is ideal for making measurements on proteins or other types of nanoparticles. Laser Diffraction methods can reliably size particles down to 100 nm or so.