Effect of Green function model for the ultrasonic time reversal based super resolution imaging algorithm

In this paper, the effect of Green function model on the ultrasonic time reversal (TR) based super resolution (SR) imaging algorithm has been investigated. Time reversal with multiple signal classification (TR-MUSIC) and phase-coherent multiple signal classification (PC-MUSIC) have been introduced as the typical TR based SR imaging algorithms. Point spread function modelling has been implemented to compare the performance of TR-MUSIC and PC-MUSIC when different Green function models were applied in the imaging process. An experimental ultrasonic array imaging system has been built to capture the real ultrasonic array data from the steel sample with a EDM line, which can be considered as the extended target. It is shown that PC-MUSIC is sensitive to the Green function model when compared with TR-MUSIC. When proper Green function model is chosen, the shape of extended target in solid can be distinguished and its size can be evaluated based on PC-MUSIC image.