NEAR-FIELD ULTRASONIC RAYLEIGH-WAVES FROM A LASER LINE SOURCE

The generation of Rayleigh waves by a thermoelastic laser line source was studied to establish a quantitative basis for using this source in nondestructive testing and in materials characterization. Experiments using interferometric detection were carried out which showed that, f or the near held of the line source, the Rayleigh pulse is a monopolar depression of uniform amplitude. A theoretical model was developed wh ich led to an approximate expression in closed form for the normal sur face displacement of the Rayleigh wave. Quantitative agreement was fou nd for a parameter-free comparison between theory and experiment for t he Rayleigh wave characteristics in both time and frequency domain.