Laser Doppler vibrometer with body vibration compensation

Abstract

We report the development of a novel dual-beam laser Doppler vibrometer (LDV) that can eliminate the perturbation due to the vibrometer body vibration without any external reference surface. A residual laser beam from the beamsplitter is used to pick up the vibration of the damper, which is mounted in the vibrometer, and is combined with the reference beam at the photodetector. The output signal of this detector and the main signal are processed to extract the object vibration, using a least-mean-squares adaptive algorithm. It is shown experimentally that the slowly varying statistics of the body vibration, which are valid in most practical cases, can be effectively removed from the measured signal using digital signal processing (DSP) technology. (C) 2003 Society of Photo-Optical Instrumentation Engineers.