THE LASER TORSIONAL VIBROMETER - A STEP FORWARD IN ROTATING MACHINERYDIAGNOSTICS

This paper describes the development of the laser torsional vibrometer since its invention at the Institute of Sound and Vibration Research, University of Southampton in 1983. The theory of laser vibrometry mea surements is first introduced together with a description of early att empts to harness the technology for torsional vibration measurement th rough use of a cross-beam laser Doppler velocimeter. This is followed by the theory for the laser torsional vibrometer itself. A measurement s section then describes results taken by the first prototype built at ISVR and compares these with the cross-beam velocimeter in a controll ed experiment. Further tests with the commercial version of the instru ment, produced by Bruel and Kjaer Ltd as the Type 2523 Laser Torsional Vibration Meter, are described, involving checks with the well known Hooke's joint. Results from an investigation into torsional vibration damper performance are also presented. The sensitivity of the instrume nt is dealt with in detail before practical considerations are describ ed. The laser torsional vibrometer has solved a particularly difficult metrology problem and is now used on a worldwide basis. It is rapidly gaining acceptance as the standard means of measuring torsional vibra tion. (C) 1996 Academic Press Limited