Synthetic Aperture Focusing Technique in High - Frequency Ultrasound Imaging to Locate Layer Delamination

In this proposed paper the synthetic aperture focusing technique (SAFT) is applied to extend the depth of focus for spherically focused ultrasound transducers. This technique uses a virtual source element in the geometrical focus of the transducer. Initial experiments with a 50 μm copper wire are conducted to investigate the efficacy of SAFT-processing for positive and negative defocus. Furthermore delamination of an adhesive join is tested. Compared to the common B-mode ultrasonic imaging which can only detect the presence of layer delamination the proposed SAFT can accurately locate the position of the delamination.