ANISOTROPY AND SPATIAL COHERENCE OF ULTRASONIC SPECKLE IN COMPOSITES

We briefly present experimental as well as theoretical results on measurements of spatial coherence of ultrasonic pulsed waves in random scattering media, particularly composite materials. We show that a given medium can behave either coherently or incoherently depending on the orientation of the ultrasonic beam, and what this implies in terms of characterization, speckle reduction and defect detection.