Autofocus imaging: Experimental results in an anisotropic austenitic weld

J. Zhang*, B. W. Drinkwater, P. D. Wilcox, A. Hunter

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference Contribution (Conference Proceeding)


The quality of an ultrasonic array image, especially for anisotropic material, depends on accurate information about acoustic properties. Inaccuracy of acoustic properties causes image degradation, e.g., blurring, errors in locating of reflectors and introduction of artifacts. In this paper, for an anisotropic austenitic steel weld, an autofocus imaging technique is presented. The array data from a series of beacons is captured and then used to statistically extract anisotropic weld properties by using a Monte-Carlo inversion approach. The beacon and imaging systems are realized using two separated arrays; one acts as a series of beacons and the other images these beacons. Key to the Monte-Carlo inversion scheme is a fast forward model of wave propagation in the anisotropic weld and this is based on the Dijkstra algorithm. Using this autofocus approach a measured weld map was extracted from an austenitic weld and used to reduce location errors, initially greater than 6mm, to less than 1mm. © 2012 American Institute of Physics.

Original languageEnglish
Title of host publicationAIP Conference Proceedings
EditorsDO Thompson, DE Chimenti
Place of PublicationMELVILLE
PublisherAmerican Institute of Physics (AIP)
Number of pages8
ISBN (Print)978-0-7354-1013-8
Publication statusPublished - 13 Jul 2012
Event38th Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE 2011) - Burlington, VT, United States
Duration: 17 Jul 201122 Jul 2011
Conference number: 38


Conference38th Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE 2011)
Abbreviated titleQNDE 2011
Country/TerritoryUnited States
CityBurlington, VT


  • Anisotropic Media
  • Austenitic Weld
  • Autofocus
  • Ultrasonic Arrays


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