Non-contact measurement of rotating shaft characteristics using optical fibre techniques

A noncontact sensor for the measurement of angular velocity and torsional strain present in rotating shafts utilizing optical fibers is reported. Originally a system was developed capable of measuring angular velocity over a range from 5 to 1000 Hz to a resolution of 1 Hz relying solely upon variations in the intensity of reflected light produced by the surface profile of the rotating shaft. By adding a second identical channel collecting data at a different point along the shaft the signals may be cross-correlated to indicate changes in the relative phase of the two points. From this information torques up to 0.16 Nm have been detected.