Description of a coherent light technique to detect the tangential and radial vibrations of an arch dam

Abstract

This paper describes a technique in which a laser light vibration sensor based on a Michelson interferometer is used. With a 5 mW laser the instrument will make measurements on a moving target at ranges greater than 200 m without using retro-reflective materials. Careful optimization of the electro-optic design reduces the effects of environmental disturbances and allows vibration amplitude resolution of 0·2 μm with a flat response in the bandwidth 0·1-150 Hz. Field tests and actual measurements of the radial and tangential displacements of an arch dam are shown. © 1982.