Title :
Differential fibre-optic sensing of laser-generated ultrasound
Author :
Williams, B.A. ; Dewhurst, R.J.
Author_Institution :
Dept. of Instrum. & Anal. Sci., Univ. of Manchester Inst. of Sci. & Technol., UK
fDate :
3/2/1995 12:00:00 AM
Abstract :
A differential fibre-optic device has been developed for noncontact detection of laser-generated ultrasound. Using a 5 mW He-Ne laser as the source, laser beam delivery on to the sample of the surface utilised a singlemode fibre and lens combination. When photoacoustic ultrasonic transients propagated across the surface, the incident spot was perturbed. With backscattered light monitored by a fibre-optic bundle incorporating differential photodetection. Symmetric and asymmetric Lamb wave modes have been observed in a 50 μm aluminium sheet, as have longitudinal and Rayleigh waves in a 30 mm-thick sample
Keywords :
Rayleigh waves; fibre optic sensors; laser beam applications; photoacoustic effect; photodetectors; surface acoustic waves; ultrasonic materials testing; 30 micron; 5 mW; 50 micron; Al; Al sheet; He-Ne; NDT; Rayleigh waves; US applications; asymmetric Lamb wave modes; backscattered light monitor; differential fibre-optic sensing; differential photodetection; fibre-optic bundle; laser-generated ultrasound; longitudinal waves; noncontact detection; photoacoustic ultrasonic transients; single-mode fibre; singlemode fibre/lens combination; symmetric Lamb wave modes;
Journal_Title :
Electronics Letters
DOI :
10.1049/el:19950235
