Diffuse field full matrix capture for near surface ultrasonic imaging

This article reports a technique for near-surface ultrasonic array imaging. Information equivalent to an undelayed full matrix of inter-element responses is produced through cross-correlation of a later time diffuse full matrix. This reconstructed full matrix lacks the nonlinear effects of early time saturation present in a directly acquired response. Consequently the near-surface material information usually obscured by this effect is retrieved. Furthermore it is shown that a hybrid full matrix formed through a temporally weighted sum of coherent and reconstructed matrices allows for effective near-surface and bulk material imaging from a single direct-contact experimental realisation.