Laser_vibrometry_pseudo_vibrations[1].pdf (334.77 kB)
Laser vibrometry: pseudo-vibrations
journal contribution
posted on 2012-04-11, 13:58 authored by Steve Rothberg, J.R. Baker, Neil A. HalliwellThe application of Laser Doppler Velocimetry (LDV) to the measurement of
normal-to-surface vibration of a solid surface is now established as a technique
complementary to the use of an accelerometer. Several practical systems have been
developed and a number are now commercially available. Each velocirneter relies on
the same principle of operation, namely the detection of a Doppler shift, fD, in
the light scattered from a vibrating target. Fig. 1 shows a typical vibrometer
arrangement. Since the photodetector cannot respond quickly enough to detect the
light frequency directly, scattered light from the vibrating surface is mixed
with a reference beam and heterodyned on the detector surface. In addition, in
order to resolve the sign of the vibration velocity, it is necessary to pre-shift
the reference beam by a known amount, fR, resulting in an optical beat at the
detector of frequency (fR ± fD). An appropriate Doppler signal processor then
demodulates the detector signal to produce a time-resolved analogue of the target
vibration velocity (in the direction of the incident beam). Systems differ in the
method adopted to produce the reference beam frequency shift. Bragg cells [1],
diffraction gratings [2] rotating scattering discs [3] and frequency modulation
of the laser beam itself [4] have all been used successfully... (continues).
History
School
- Mechanical, Electrical and Manufacturing Engineering
Citation
ROTHBERG, S.J., BAKER, J.R. and HALLIWELL, N.A., 1989. Laser vibrometry: pseudo-vibrations. Journal of Sound and Vibration, 135 (3), pp. 516 - 522.Publisher
© ElsevierVersion
- AM (Accepted Manuscript)
Publication date
1989Notes
This article was published in the Journal of Sound and Vibration [© Elsevier] and the definitive version is available at: http://dx.doi.org/10.1016/0022-460X(89)90705-0ISSN
0022-460XPublisher version
Language
- en