Rapid quantification of 3D ultrasound fields with wavefront sensing and Schlieren tomography.

The rapid and precise characterization of three-dimensional (3D) pressure fields inside water is paramount for ultrasound (US) applications in fields as relevant as biomedicine and acoustic trapping. The most conventional way is to scan point-by-point a needle hydrophone across the field of interest, which is an intrinsically invasive and slow process. With typical acquisition times of hours and even days, this method remains impractical in many realistic scenarios.

Sizing the Depth and Width of Narrow Cracks in Real Parts by Laser-Spot Lock-In Thermography.

We present a complete characterization of the width and depth of a very narrow fatigue crack developed in an Al-alloy dog bone plate using laser-spot lock-in thermography. Unlike visible micrographs, which show many surface scratches, the thermographic image clearly identifies the presence of a single crack about 1.5 mm long.