Improving the imaging performance of non-standard arrays
J Kirkpatrick1, J Potter2, R Smith1 and P Wilcox1
1University of Bristol, Bristol, UK
2Verasonics, Washington, USA
The results of two projects focusing on non-standard ultrasonic arrays for non-destructive testing are shown. Firstly, improvements to row-column addressed (RCA) arrays are demonstrated through the application of a new imaging algorithm based on the total focusing method. Modelling is used to evaluate the performance of this new algorithm. An improvement in the accuracy of sizing flat-bottom holes is shown experimentally using a commercial RCA array. The average difference between the −6 dB drop width and the nominal drill-bit diameter was improved compared to plane B-scan algorithms from (1.29 ± 0.07) mm to (0.23 ± 0.04) mm. Secondly, data collection speed using laser ultrasonic arrays is improved through the use of ultrasonic diffuse fields. Laser ultrasonic array data is collected in a few minutes instead of several hours with little reduction in signal-to-noise ratio (SNR) compared to previous literature in this area. The data collection method also has other benefits, including a more favourable directivity in transmit and receive of the final array and, consequently, the elimination of Rayleigh wave artefacts from the final image.
