Imaging defects by one-dimensional synthetic aperture focussing technique

The advantages of modern synthetic aperture focussing techniques versus conventional ultrasonic testing systems are explained. The LINE-SAFT method uses the complete RF-signal at each probe position and forms a B-scan image with an axial and lateral resolution of 1-2 wavelengths. Data have been processed in pulse-echo, tandem, pitch and catch with piezoelectric and with EMAT transducers on plane and curved specimens. SAFT has been applied with success in the laboratory to demonstrate the achievable lateral and axial resolution of 1 wavelength and in the field on tube sheet plate, on turbine rotor shaft, on pressure vessels and on nozzle inspection. 2 refs