Three Dimensional Vibration Measurements Using a Five-Axis Scanning Laser Vibrometry System

Abstract

This paper describes an experimental facility designed to measure three-dimensional velocity components using a five-axis laser vibrometry system. A single-point laser Doppler vibrometer (LDV) is mounted on three orthogonal translation stages, and the beam is directed to the target specimen by means of a mirror mounted at the intersection of the axes of two rotational stages. The result is a system with which the vibration of points on the surface of the test specimen can be measured from multiple angles, and these multiple measured components of the surface velocity are combined to determine the full velocity vector in three-dimensions. This system allows collection of a richer data set for more detailed vibration analysis, measurement of vibration of non-planar surfaces, and greater control over measurements compared to conventional single-beam scanning LDV, while greatly reducing experimental facility costs compared with threedimensional LDV systems that use multiple lasers.