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Imaging with HOLOSAFT

: Müller, W.; Schäfer, G.; Schmitz, V.

Berkhout, A.J.; Ridder, J.; Wal, L.F. van der:
Acoustical Imaging. Vol.14
New York/N.Y.: Plenum Press, 1985 (Acoustical imaging 14)
International Symposium on Acoustical Imaging <14, 1985, Den Haag>
Conference Paper
Fraunhofer IZFP ()
Auflösungsvermögen; synthetische Apertur; Ultraschall

Synthetic aperture methods are used to achieve an almost reliable and precise image critical material defects like inner or surface connected, single or branched cracks. To estimate the quality of those images i.e. sensitivity and lateral and axial resolution, parameters important for the data acquisition such as wavelength, bandwidth and probe dimensions have to be discussed. Methods like ultrasonic holography or synthetic aperture focussing techniques claim to have the highest possible lateral (holography and SAFT) and axial (SAFT) resolution without additional data processing. Theoretically derived formulas to calculate the resolution of the imaging system deviate more or less from the practical experience obtained during the last years. In addition it is very important that ultrasonic imaging methods are able to differentiate between defect echoes, form echoes and noise without any preknowledge and arbitrarily chosen amplitude thresholds.