Sorting matter in a flow by comparing reflectance intensities at different wavelengths

摘要

Sorting foreign matter in a flow, comprising identifying objects within a flow; for each object, determining reflectance intensities in at least two different wavelengths or ranges of wavelengths; and for each identified object, comparing the reflectance intensities at the at least two different wavelengths or ranges of wavelengths to a reference intensity profile. The object is characterized as foreign matter when the reflectance intensities at the at least two different wavelengths or ranges of wavelengths fall within a predetermined region of the reference intensity profile. The object may be deflected from the flow when it is identified as foreign matter. Images may be acquired and processed to identify the objects in the flow, these images may be in the near or short infra-red spectrum. An illumination source 7 may be used to illuminate the flow. The objects may be food, and more specifically they may be frozen vegetables. A Camera unit 11 comprising of at least two detectors 17a, 17b and a beam splitter 21 are used to measure the reflectance intensities.