An extension of double-stage DMAS for PMUT array imaging

Piezoelectric micromachined ultrasonic transducer (PMUT) array has shown great potential for ultrasonic imaging. Current ultrasound images are reconstructed commonly using delay and sum (DAS) method. However, due to the low acoustic pressure and high electrical noise of PMUT, these algorithms have insufficient image quality when being used for solid defect imaging. This study reports a new extension of double-stage delay multiply and sum beamforming algorithm (DS-DMAS3) taking into account the spatial correlation of the received signals. Experiments are performed on graphite samples with side drilled holes. Results show that DS-DMAS3 significantly improves SNR and resolution compared to conventional methods and exhibits good applicability for PMUT imaging.