Abstract: An apparatus for measuring the profile of a moving object has a cassette housing (161) having an aperture (31) for the passage of the object. At least two spaced light emitters (41, 47) and associated light detectors (42, 48) are positioned so that the light detectors and light emitters are spaced on opposing sides of the object such that a particular profile of the object may be measured. The light detector is, preferably, a linear array of elements. Means are provided for producing a warning if the profile is outside a predetermined tolerance.