Synthetic aperture focusing techniques for ultrasonic imaging of solid objects

Synthetic aperture focusing technique (SAFT) has been used in non-destructive testing mainly in its simplest form that mimics acoustic lenses used for focusing ultrasonic beams at a point of a solid object or structure. This paper presents a review of SAFT algorithms applied for post-processing of ultrasonic data acquired in non-destructive inspection of metals. The performance of SAFT in terms of its spatial resolution and suppression of the backscattering from material structure is discussed. The discussion is illustrated by the experimental data obtained from the ultrasonic inspection of test specimens with artificial defects (side drilled holes).