Optical sorting by surface examination
Detection of foreign bodies in food products

This technique uses cameras to examine the surface of a circulating particulate product, illuminated under controlled conditions.

The criteria examined are shape, particle size, and color in the broadest sense: the spectrum of light reflected by the object in the visible, infrared (IR) or ultraviolet (UV) range. Products are illuminated by lamps that deliver the required spectrum: high-frequency neon, incandescent lamps (visible or IR), high-power light-emitting diodes (LEDs).