Ultrasound Array Probe: Signal Processing in Case of Structural Noise

Abstract

This work focuses on non-destructive examinations using array probe ultrasonic waves on complex materials generating a high structural noise on the examined area. During an ultrasonic examination, multiple scattering of the ultrasonic waves at the grain boundaries makes the distinction between this structurally induced noise and a potential defect challenging. The difficulty of the interpretation can moreover be increased in the near surface area because of the subsurface wave. In order to ease the analysis of these acquisitions, some numerical processing methods are proposed. Statistical properties of the imaging results (for instance, total focusing method or plane wave imaging) are first calculated on several sensor positions. These statistical properties are then used to post-process the imaging results and enhance any signal values that do not belong to the structural noise expected statistics. The method, called “CORUS,” has been successfully tested on cast austenoferritic stainless steel coarse-grained mock-ups, with several dB gain compared to the classical total focusing method. It is now integrated in a civa software plugin and in a prototype version of the real-time PANTHER-phased-array acquisition system from Eddyfi Technologies.