Real-Time Quantitative Ultrasonic Inspection

Most frequently applied ultrasonic inspection techniques measure the reflectivity of geometric scatterers that are caused by impurities, flaws and defects in the material. Based on the echo sounder principles, the reflector has to be insonified by directed sound pulses. This requires a large number of transducers with different incident angles and sound field patterns, which are more and more replaced by phased array sensors. Phased array inspection systems can control the insonification direction and the focus of the applied sound field, but they do not alter the principles of multi-angle and multifocus inspection; the resulting scanning speed limitation is obvious. In addition, flaw imaging only displays the position and amplitude height of the reflection and does not provide an image of the actual shape of the reflector. Thus, the evaluation of state-ofthe-art ultrasonic imaging is based on the extension and maximum amplitude of the identified reflector applied to specified reference reflectors. A more quantitative assessment of the findings requires human or future artificial expert knowledge. We have developed a new concept for real-time quantitative ultrasonic imaging at high speed scanning. The “Sampling Phased Array” ultrasonic system and the use of distributed apertures based on “SynFoc” algorithms permit imaging of reflectors independent from the insonification direction. Only one insonification is required to image the cross section (Sector Scan or B-Scan) with an arbitrary number of virtual incidence angles at repetition rates of up to 6 kHz. Due to the virtual coverage of all incidence angles and the simultaneous focusing of each image pixel using the synthetic aperture algorithms (SynFoc), the real-time 3-D result presentations approach today’s demands for quantitative defect imaging. We have planned to integrate the interaction of the sound field with structured geometric scatterers, including mode conversion phenomena, for example. We are