Measuring Steel Strip Cleanliness : A Sensor System Based on Optics Phenomena

Steel cleanliness is very important prior to any steel coating process. A novel cleanliness sensor for flat steel products has been designed for use on the production line. The sensor is based on the optical reflectivity of dirty steel, which has been analyzed to determine how the incident light beam is dispersed. To design the optical circuit, the effect of steel lamination/processing marks on light dispersion was quantified. Fresnel lenses were employed to concentrate the dispersed beam again on a photodiode.