Imaging-based particle sizing system combining scattered-light imaging and particle-shade imaging for submicron particles

Particle-processing industries, such as those for manufacturing pharmaceuticals, ceramics and polymers, require accurate and reliable monitoring and controlling techniques for particle-size distribution to stabilize product quality and maximize productivity. Imaging is a highly valuable monitoring technique because it can measure precise particle-size distributions by detecting particles individually and also can measure particle shape. However, detecting submicron particles or smaller is difficult due to the diffraction of light in the optics. We propose an imaging-based monitoring system that extends the detectable particle-size range towards the submicron level by combining particle-shade and scattered-light imaging. The system consists of newly developed optics and an analysis algorithm. We evaluated the accuracy of the proposed system using polystyrene standard spheres.