An apparatus for monitoring a thickness of a film in motion. The apparatus comprises a roller for receiving and supporting the film in motion, the roller being adapted to rotate about an axis of rotation. The apparatus also comprises a position detector for detecting when the roller is in a specific angular position as the roller rotates about the axis of rotation. The apparatus further comprises a measurement unit aligned with a specific portion of the roller and coupled to the position detector. The measurement unit is responsive to a detection of the roller being in the specific angular position to measure the thickness of the film.