Patent ID: 8561313

Claim:
An apparatus for measuring a thickness of a film bubble, comprising: an annular guide track that extends in a circumferential direction of the film bubble with a constant spacing relative to the film bubble, a single carriage guided on the guide track, a thickness measuring head carried on the carriage and facing a peripheral surface of the film bubble, a cantilever having one end pivotally connected to the carriage, the measuring head being connected to a free end of the cantilever via an articulated joint, a compensating drive mechanism for correcting a change in the orientation of the measuring head resulting from a pivotal movement of the cantilever that is associated with said articulated joint, wherein the cantilever is pivotable in a plane that extends in parallel with a plane of the guide track, and a control unit adapted to determine an azimuthal position of the measuring head relative to a central axis of the film bubble on the basis of an azimuthal position of the carriage on the guide track and the angular position of the cantilever relative to the carriage, said control unit being further adapted to assign measurement results provided by said measuring head to said azimuthal positions.