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 non-destructive testing (NDT), there have been advancements in software algorithms allowing for fully-focused 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 a receiver, sufficient time-domain signals may be acquired to allow fully-focused imagery to be generated.