ROTHBERG, S.J., BAKER, J.R. and HALLIWELL, N.A., 1990. On laser vibrometry of rotating targets: effects of torsional and in-plane motion. Journal of Laser Applications, 2 (1), pp. 29 - 36.
Vibration measurements on rotating surfaces are often referred to in ·the
commercial literature as a major application of laser Doppler vibration
transducers. This paper examines such use of these instruments and shows
how the presence of a velocity component due to the rotation itself leads
to spurious measurement dependence on both torsional vibration and motion
perpendicular to the line of incidence of the laser beam. In addition, the
scale of this dependence increases with both rotation speed and
perpendicular distance between the line of incidence and a parallel line
through the centre of rotation. These phenomena are investigated
theoretically and excellent agreement is found when compared with
experimental data. Two solutions are suggested; the first involves careful
alignment of the laser beam whereas the second requires two simultaneous,
orthogonal measurements to be made. If neither method is adopted it is entirely conceivable that the intended solid body vibration measurement may
be masked at many frequencies of interest.