Development of three-dimensional measurement system using laser doppler vibrometers

The objective of this paper is to develop a vibration measurement system using three laser Doppler vibrometers. This makes possible to measure three-dimensional behavior of an object spatial densely as well as high accurately. Measurement principle of three-dimensional vibration using LDVs is based on the geometrical transformation of coordinates. At first, to validate the principle, fundamental system was developed. Then, the system was applied to measurement of train-induced vibration at a steel box girder bridge. Since local three-dimensional vibration was captured, its applicability was confirmed. Finally, three-dimensional vibration measurement system allowing a scan and an arbitrary setting for more suitable for on-site measurement was developed. In the system, measurement procedure was formulated in order to identify configurations of each LDV. Laboratory experiment showed the validity.