Abstract: An apparatus and a method for inspecting cullet for the presence of unwanted materials among the pieces of glass. A light source such as a laser directs light onto the cullet. At least one array of at least two light detectors is positioned to detect reflected light from the cullet. The detectors differentiate between non-uniformly scattered light from the cullet and generally uniformly scattered light from the debris. Signalling means are provided to signal the differentiation thereby to indicate the presence of debris in the cullet under inspection. When cullet is present on a moving cullet belt, light from the light source is intermittently scanned over the cullet in a raster-type scan. A multi-faceted rotatable mirror may be employed intermittently to reflect light onto the cullet.