Abstract: The leads of a QFP are examined by an optical system. The optical system includes a sensor head having two lasers, the outputs of the lasers being fed to a beam splitter which provides outputs at right angles to each other, and a ring-light which is disposed under the beam splitter and in actual alignment with the beam splitter. The sensor head is carried by a carriage in a single plane along two transverse directions. The carriage moves the sensor heads so as to examine one lead at a time along the peripheral edges of the QFP.