PSD - Particle Size Distribution
Particle Size Distribution measurements aim to determine the average and range of particle sizes in a powder. Laser diffraction is used to make this measurement.
Laser diffraction depends upon analysis of the "halo" of diffracted light produced when a laser beam passes through a dispersion of particles in air or in a liquid. The angle of diffraction increases as particle size decreases, so that this method is particularly good for measuring sizes between 0.1 and 3,000 μm. Advances in sophisticated data processing and automation have allowed this to become the dominant method used in industrial PSD determination. This technique is relatively fast and can be performed on very small samples. A particular advantage is that the technique can generate a continuous measurement for analyzing process streams.
SEM - Electron Microscopy