Characterizing defects in multi-layer materials using guided ultrasonic waves

A brief description is given of a methodology that exploits guided ultrasonic waves, lasers and fiber optics, and simultaneous time-frequency analysis to interrogate the state of a material, component, or structure. This system offers a means by which surface-guided (Lamb and Rayleigh), broadband, ultrasound can effectively be generated and detected in a wide variety of materials in real time and in a non-contact, non-invasive fashion. The propagating ultrasound interrogates the host material in a manner providing a wealth of information when coupled with application of the Gabor wavelet transform to broadband dispersive waveforms. Recent results are presented pertaining to delamination detection within layered copper/ polymer films. (C) 2002 Elsevier Science Ltd. All rights reserved.