Sampling phased array - a new technique for ultrasonic signal processing and imaging

Over the past 10 years, the improvement in the field of microelectronics and computer engineering has led to significant advances in ultrasonic signal processing and image construction techniques that are currently being applied to non-destructive material evaluation. A new phased array technique, called 'Sampling Phased Array', has been developed in the Fraunhofer Institute for Non-Destructive Testing([1]). It realises a unique approach of measurement and processing of ultrasonic signals. The sampling phased array principle makes use of the measurement of elementary waves generated by individual elements of a sensor array to reconstruct the composite phased array signal for any arbitrary angle or focus depth. The use of special signal processing and image reconstruction algorithms allows generating A-scans of several angles and/or sector-scans, which can be implemented in real time. With parallel computing structures, this principle is used for automatic testing systems at very high inspection speed. A comparative study was done with conventional phased array and the sampling phased. array technique. The study shows that the signal characteristics in both techniques are equal. In addition, the sampling phased array technique is significantly beneficial in many aspects such as quality of information in specific cases, inspection speeds and adaptability to specific inspection tasks in comparison to conventional phased array. The development results, including relevant test methodology and equipment aspects, are presented in the current work, together with the benefits for industrial ultrasonic inspection.