System for noncontact measurement of torsional vibrations of shafts

Steen Gruner Hanson

doi:10.1117/12.233002

13 February 1996 System for noncontact measurement of torsional vibrations of shafts

Steen Gruner Hanson

Proceedings Volume 2729, Optical Velocimetry; (1996) https://doi.org/10.1117/12.233002
Event: Optical Velocimetry, 1995, Warsaw, Poland

Abstract

A method for measurement of rotational speed and torsional vibrations for semireflective targets is presented. The method is parallel to time-of-flight velocimetry in that a delay time between the passage of a speckle pattern between two detectors is tracked. In this setup the delay corresponds to the passage of scattering structures positioned angularly on the target, here a cylindrical shaft. This is facilitated by observing the subjective speckles in the Fourier plane with respect to the object. The method is proven independently of the location of the object, as well as independently of the diameter of the object. Further, the signal strength is considerably higher than compared with previous laser-based noncontact systems. An implementation is presented and the specifications are given. Tracking of the time delay giving the maximum crosscovariance between the two signals is facilitated by a delay locked loop based on a one-bit digitization of the two input signals.

Citation Download Citation

Steen Gruner Hanson "System for noncontact measurement of torsional vibrations of shafts", Proc. SPIE 2729, Optical Velocimetry, (13 February 1996); https://doi.org/10.1117/12.233002

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