The three-dimensional laser vibrometer

Abstract

In the field of structural acoustics, two of the central tools necessary for studying the physics of interactions and vibration transmission paths are a measure of structural intensity and the generation of k-ω dispersion relationships. It is particularly important in the study of fluid-loaded structures to be able to characterize both the in-plane and out-of-plane motions in order to identify mechanism conversions at apertures and discontinuities. A noncontact underwater probe for measuring simultaneously the three components of vibration induced displacement on the surface of submerged structures has been constructed. Optical fiber is used so that a compact optical probe with no electronics is the only device in the water. The probe is used to measure the three components of motion of a point on the surface of a target from a distance of approximately 2 ft. Data for acoustic studies are obtained by collecting data at a series of points on a target surface. Experimental results will be presented. An analysis of the sensitivity, frequency response, and detection threshold of the system will also be included.