Development of a Method for the Measurement of Particle Size and Velocity based on Projection onto a Variable Frequency Grating

Irregular particles down to approximately 3.8 μm have been sized by imaging them onto a variable frequency grating using laser illumination. Velocity can also be determined. The method was successful for certain particle types that were rough or irregular, partly absorbing or translucent. It was not successful for transparent spheres that display glare spots in the image, or other particles that produce localised regions of high brightness.