Separation Technique for Raisins and Stems Utilizing Characteristics of Polarization

We have improved the accuracy of the laser separation of stems from raisin samples on the basis of the degree of polarization of scattered light from raisins and stems. The specular reflection from wet raisins was minimized by regulating the degree of polarization of their scattered emissions. Wet and dry raisins were therefore judged as the same samples. Using these polarization characteristics, wet or dry raisins were separated from their stems in our laser inspection system. The detection error was reduced from 25 to 7% in our system.