Laser Doppler vibrometer

About: Laser Doppler vibrometer is a research topic. Over the lifetime, 6319 publications have been published within this topic receiving 76068 citations.

Laser detection of sound

Abstract: A differential laser Doppler velocimeter (LDV) has been assembled and tested to provide noninvasive absolute measurements of acoustic particle displacements of standing waves generated in a water‐filled tube. The principle of the technique [see K. J. Taylor, J. Acoust. Soc. Am. 59, 691–694 (1976)] is to measure the Doppler shift of laser light scattered from colloidal microparticles oscillating under the action of an acoustic field. The system tested is capable of detecting particle displacements of the order of a few nanometers with a bandwidth of several kilohertz. The performances and limitations of the system are discussed. In particular, the effect of Brownian motion is shown to produce only negligible broadening of the spectral density of the signal of interest. The sensitivity of the present LDV system is estimated to be very close to the shot noise limit of the photomultiplier tube used to detect the Doppler shift of the scattered light. Experimental results are obtained under controlled laborator...

Sound field measurements based on reconstruction from laser projections

Abstract: In this paper, we describe some new sound field measurement methods by using a laser Doppler vibrometer (LDV). By irradiating the reflection wall with a laser, we can observe the light velocity change that is caused by the refractive index change from the change in air density. It means that it is possible to observe the change of the sound pressure. We measured a sound field projection on a 2D plane using a scanning laser Doppler vibrometer (SVM) which can visualize a sound field. And we made a 3D sound field reconstruction from some 2D laser projections based on computed tomography (CT) techniques. We made the reconstructed image for the sound field near the loudspeaker or in the room.