EFFICIENT DATA CAPTURE AND POST-PROCESSING FOR REAL-TIME IMAGING USING AN ULTRASONIC ARRAY

Over the past few years, ultrasonic phased arrays have shown good potential for non-destructive testing (NDT), thanks to high resolution imaging algorithms. Many algorithms are based on the full matrix capture, obtained by firing each clement of an ultrasonic array independently, and collecting the data with all elements. Because of the finite sound velocity in the specimen, two consecutive firings must be separated by a minimum time interval. Therefore, more array elements require longer data acquisition times. Moreover, if the array has N elements, then the full matrix contains 1 12 temporal signals to be processed. Because of the limited calculation speed of current computers, a large matrix of data can result in long post-processing times. In an industrial context where real-time imaging is desirable, it is crucial to reduce acquisition and/or post-processing times. This paper investigates methods designed to reduce acquisition and post-processing times for the total focusing method and wavenumber imaging algorithms. Limited transmission cycles are used to reduce data capture and post-processing. Post-processing times arc further reduced by demodulating the data to temporal baseband frequencies. Results arc presented so that a compromise can be made between acquisition time, post-processing time and image quality.