Blar i forfatter "Olofsson, Tomas"

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    • Synthetic Aperture Focusing of Ultrasonic Data From Multilayered Media Using an Omega-K Algorithm 

      Skjelvareid, Martin H.; Olofsson, Tomas; Birkelund, Yngve; Larsen, yngvar (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      The synthetic aperture focusing technique (SAFT) is used to create focused images from ultrasound scans. SAFT has traditionally been applied only for imaging in a single medium, but the recently introduced phase shift migration (PSM) algorithm has expanded the use of SAFT to multilayer structures. In this article we present a similar focusing algorithm called multi-layer omega-k (MULOK), which ...

    • Three-dimensional ultrasonic imaging in multilayered media 

      Skjelvareid, Martin Hansen; Olofsson, Tomas; Birkelund, Yngve (Conference object; Konferansebidrag, 2011)
      The synthetic aperture focusing technique is a method for focusing ultrasonic scans used in nondestructive testing. Traditionally, the technique has mainly been used for contact testing, where the speed of sound is constant throughout the whole medium, but a number of recently proposed algorithms have extended the technique to multilayered media. One important application for such multilayer methods ...

    • Ultrasonic imaging of pitting using multilayer synthetic aperture focusing 

      Skjelvareid, Martin Hansen; Olofsson, Tomas; Birkelund, Yngve (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      Synthetic aperture focusing is known to increase both the lateral resolution and signal-to-noise level of pulse-echo ultrasonic images. In this paper, the use of synthetic aperture imaging for detection and sizing of pitting in a plate is considered. It is assumed that a water layer is present between the transducer and the plate, and that the pitting is on the back side of the plate, seen from the ...