Synthetic Aperture Focusing Techniques in the Near Field of a Focused Transducer

Synthetic aperture focusing techniques (SAFT) represent a special class of beam steering algorithms [1] that are used to improve the resolution and signal-to-noise ratio (SNR) of ultrasonic images. It has been traditionally performed using focused transducers, with the test material located in a region where the ultrasonic beam diverges beyond the focal point [2,3]. This is to ensure that the transducer collects enough data relating to the defect. Operating in the far-field of the transducer where the spatial field variations are slow minimizes the error