Abstract
Using laser-generated Rayleigh waves in the thermoelastic regime asan ultrasonic source, a range of ultrasonic detector systems have beenevaluated experimentally for their sensitivity. Systems examined were thosebased on electromagnetic acoustic transducers (EMATs), a non-steady statephoto-emf detector, a confocal Fabry-Pérot interferometer (CFPI) and adifferential optical beam deflection (OBD) detector. These detector systemshad their own range of frequency responses within the range of approximately100 kHz to 140 MHz. However, experimental conditions in this study limited theupper frequency range to 22 MHz. For comparison, signal-to-noise ratios werenormalized with respect to both the experimental bandwidth, and, in the caseof laser detection, the incident laser intensity. Results showed that forremote monitoring at a distance greater than 0.2 m, optical systems based onthe photo-emf detector and the CFPI offered similar performances from amachine-finished aluminium surface. OBD measurements are not possible on sucha surface. However, for typical stand-off distances of 0.25 mm or less,cost-effective EMATS provided an alternative form of detector.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
