During more than ten years of ultrasonic inspection of concrete members the inspection methods achieved an enormous progress. This is due to the development of broadband transducers in the low frequency range (centre frequency 80 kHz to 250 kHz) and to the application of synthetic aperture measuring and evaluation techniques [ 1-3]. Since 1994 the Fraunhofer IZFP and BAM co-operate in the area of ultrasonic imaging. BAM develops measuring techniques applying monostatic impulse echo measurement, twodimensional scanning of concrete elements using transducer arrays, multistatic scanning, and a scanning laser-vibrometer as ultrasonic receiver. IZFP develops and applies the data evaluation by means of reconstruction calculation (3D-SAFT; Synthetic Aperture Focusing Technique). The results obtained up to now concerning localising and investigation of tendon ducts in concrete elements, multi layer systems (for example ballast free railway tracks) and the investigation of concrete slabs [4-6] are very encouraging.
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