Advanced post-processing for scanned ultrasonic arrays: application to defect detection and classification in non-destructive evaluation.

This paper describes a number of array post-processing methods developed for scanning applications in non-destructive evaluation. The approach is to capture and process the full matrix of all transmit-receive time-domain signals from the array. Post-processing the data in this way enables a multitude of imaging modalities to be implemented, including many that could not feasibly be achieved using conventional parallel firing techniques. The authors have previously published work on imaging algorithms for improving the characterisation of defects in solids by post-processing the data from a static linear ultrasonic array. These algorithms are extended and applied to data from a scanned array. This allows the effective aperture and range of probing angles to be increased, hence improving imaging and defect characterisation performance. Practical implementation issues such as scanning speed and data transfer are discussed.