Fuente: WIPO "stone fruits" A method and apparatus for detecting the presence of an impurity within a substantially spherical object, such as a pit within a piece of stone fruit as it passes through an inspection zone. An infrared point source light emitting diode positioned on one side of the inspection zone transmits a single light beam across the inspection zone. A linear CCD array for generating a signal that is proportional to the intensity of the light transmitted through the fruit as the fruit passes through the inspection zone is provided and an optical slit for collimating the light beam on the CCD array are provided. An infrared filter is positioned between the lens and the CCD array. Thus, as the fruit passes through the inspection zone and is illuminated by the infrared light source and the intensity of the light transmitted through the fruit is received by the CCD array, a two-dimensional analyzable bit map representative of the cross-section of the object's density is produced.