Virtual Source Aperture Imaging and Calibration for Ultrasonic Inspections through Dual-Layered Media for Non-Destructive Testing

Since the introduction of full-matrix capture to NDT, there has been advancement in software algorithms allowing for fully focussed imagery to be generated. Due to the large number of time-domain signals associated with this approach processing speed is often a limiting factor. This paper describes an alternative less processor-intensive approach in which a parallel transmission of a highly divergent beam is generated to simulate a virtual point positioned some distance behind the transducer. When combined with each element of the array acting as receivers, sufficient time-domain signals may be acquired to allow fully focused imagery to be generated.
 
Keywords: ultrasonic Inspection, phased array transducer, full-matrix capture, result processing