Abstract
In all the cases in which a torque measurement is required, the use of torque trasducers presents many drawbacks, whose limits could be the intrusivity and effects on shaftline parameters. In this work, a new approach is proposed developing a non contact torque meter that can be applied on the machine shaft needless of other components. It carries out the torque measurement evaluating the torsional displacement between two distinct sections of the shaft, monitoring their roughness. As sensing principles, classical laser speckle contrast method is employed. The intensity coming up from the scattering of the rough surface is processed by a cross-correlation function. That is, the angular torsion of two distinct sections is obtained and, therefore, it is possible to point out the applied torque by the knowledge of the shaft torsional stiffness.