2D and 3D ultrasound imaging of crack-like defects with a fast reconstruction algorithm in the Fourier domain

S Robert1, L Merabet1, F Cartier1 and C Prada2
1CEA-LIST, Department of Imaging and Simulation for Nondestructive Testing, Digiteo Saclay, Bât 565, PC 120, 91191 Gif-Sur-Yvette, France
2Institut Langevin, ESPCI Paris, CNRS, PSL Research, 75238 Paris, France 

The total focusing method (TFM) was generalised about ten years ago to form images with complex ultrasound paths involving mode conversions and reflections by the specimen interfaces. The resulting multimode imaging makes it possible to fully image a vertical crack with a conventional phased array in pulse-echo mode. Recently, time domain plane wave imaging (PWI) has been explored to perform multimode reconstructions with a reduced number of transmissions compared to the TFM. In order to further accelerate the imaging process, the authors propose to combine the multimode PWI with a Fourier domain reconstruction algorithm, inspired by the method developed by J-Y Lu. In this communication, the authors compare the experimental images of crack-like defects obtained with the time-domain PWI and the Lu approach, in 2D with linear arrays, as well as in 3D with matrix arrays. The authors show that the Fourier-domain algorithm provides images equivalent to those computed in the time domain, even reducing some artifacts, while decreasing computation times by a factor between 15 and 30.