Vibration measurements using continuous scanning laser vibrometry: velocity sensitivity model experimental validation

This paper builds on a previous study in which the theoretical description of the velocity sensed by a single laser beam incident in an arbitrary direction on a rotating target undergoing arbitrary vibration was extended to continuous scanning Laser Vibrometer measurements on targets with flexible cross-sections. The velocity sensitivity model was written in terms of either laser beam orientation angles or deflection mirror scan angles, with the latter found to be most useful for continuous scanning applications. The model enables the prediction of the Laser Vibrometer output for any measurement configuration on any target. The experimental validation presented in this paper confirms that additional components appear in rotating target measurements that are associated with both the scanning system configuration and any misalignment between the scanning system and target rotation axes. This paper will show how use of the velocity sensitivity model enables the vibration engineer to make LDV measurements with confidence.