Noncontact evaluation of materials using elastic waves

Ultrasonic nondestructive testing requires normally a liquid to couple the acoustic energy from probe to the inspected object. In many cases couplants cause practical problems during inspections, therefore, noncontact solutions are sough. 

In this presentation noncontact nondestructive testing solutions will be presented. First, laser ultrasonic (LUS) system for high resolution imaging of carbon-fiber reinforced composites will be discussed. The imaging results obtained by the LUS device under thermoelastic ultrasound generation regime will be compared to X- Ray micro CT scans. 

Furthermore, it will be shown for some materials e.g. eye cornea, laser pulses cannot generate sufficient wave amplitude without introducing damage. As a solution to this problem a focused air-coupled ultrasonic transducer generating acoustic radiation force sufficient for launching waves propagating in eye cornea will be discussed. These waves can be sensed using optical coherence tomography and processed for evaluation of local cornea stiffness. In this presentation details of the acoustic device and its application to evaluation of soft materials elasticity will be presented.