A device is disclosed for the classification of a transparent component of a material flow using an optical detector unit, with allocatable optical axis which is directed toward the material flow, at least one illumination unit for illuminating the material flow from a space over the material flow, in which the optical detector unit is also contained, and a classifier, which classifies the component based on information which is recorded from the component using the optical detector unit, and a decision criterion. A retroreflector is provided at least longitudinally relative to the optical axis of the detector unit, downstream from the material flow in the viewing direction of the detector, the illumination unit provides at least two light sources, with first light source emitting light of a first type and a second light source emitting light of a second type.