Improved imaging with multi-SAFT

At the end of 1988 a research project was started to develop a practical, high-resolution imaging method for ultrasonic NDT (nondestructive testing) based on the synthetic aperture focusing technique (SAFT). It is demonstrated that multiple reflecting waves, interacting with a defect via the object boundaries, have to be included in the SAFT algorithm. The improved imaging method is referred to as Multi-SAFT. A fast calculation scheme for computing indirect wavepaths in cylindrical objects is presented. The data-acquisition method is described, and a number of modeled and experimental imaging results are given, illustrating the considerable improvements of the images obtained when applying Multi-SAFT.<>