Numerical focusing of ultrasound

Kari Lahdenperä

    Research output: Book/ReportReport

    Abstract

    The main principles and restrictions of the numerical focusing such as the acoustical holography and the synthetic aperture focusing technique (SAFT) are described. In the holography the ultimate lateral resolution is half of the wavelength. The longitudinal resolution is poor. With SAFT the longitudinal resolution is equal to pulse length. The transversal resolution is half of the wavelength or half of the diameter of the probe. The single frequency holography is optimal to image planar reflectors. When planar reflectors are inclined with respect to the aperture they can best be imaged with SAFT or multifrequency holography. Some images based on the inspections with SAFT carried out by IzfP in Saarbrcken are shown. The specimens to be tested were supplied by the Technical Research Centre of Finland (VTT). The results were in good agreement with earlier measurements with surface wave method.
    Original languageFinnish
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    Number of pages21
    ISBN (Print)951-38-2743-7
    Publication statusPublished - 1986
    MoE publication typeD4 Published development or research report or study

    Publication series

    SeriesValtion teknillinen tutkimuskeskus. Tiedotteita
    Number642
    ISSN0358-5085

    Keywords

    • ultrasonic tests
    • focusing
    • holography

    Cite this

    Lahdenperä, K. (1986). Numerical focusing of ultrasound. Espoo: VTT Technical Research Centre of Finland. Valtion teknillinen tutkimuskeskus. Tiedotteita, No. 642
    Lahdenperä, Kari. / Numerical focusing of ultrasound. Espoo : VTT Technical Research Centre of Finland, 1986. 21 p. (Valtion teknillinen tutkimuskeskus. Tiedotteita; No. 642).
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    title = "Numerical focusing of ultrasound",
    abstract = "The main principles and restrictions of the numerical focusing such as the acoustical holography and the synthetic aperture focusing technique (SAFT) are described. In the holography the ultimate lateral resolution is half of the wavelength. The longitudinal resolution is poor. With SAFT the longitudinal resolution is equal to pulse length. The transversal resolution is half of the wavelength or half of the diameter of the probe. The single frequency holography is optimal to image planar reflectors. When planar reflectors are inclined with respect to the aperture they can best be imaged with SAFT or multifrequency holography. Some images based on the inspections with SAFT carried out by IzfP in Saarbrcken are shown. The specimens to be tested were supplied by the Technical Research Centre of Finland (VTT). The results were in good agreement with earlier measurements with surface wave method.",
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    Lahdenperä, K 1986, Numerical focusing of ultrasound. Valtion teknillinen tutkimuskeskus. Tiedotteita, no. 642, VTT Technical Research Centre of Finland, Espoo.

    Numerical focusing of ultrasound. / Lahdenperä, Kari.

    Espoo : VTT Technical Research Centre of Finland, 1986. 21 p. (Valtion teknillinen tutkimuskeskus. Tiedotteita; No. 642).

    Research output: Book/ReportReport

    TY - BOOK

    T1 - Numerical focusing of ultrasound

    AU - Lahdenperä, Kari

    PY - 1986

    Y1 - 1986

    N2 - The main principles and restrictions of the numerical focusing such as the acoustical holography and the synthetic aperture focusing technique (SAFT) are described. In the holography the ultimate lateral resolution is half of the wavelength. The longitudinal resolution is poor. With SAFT the longitudinal resolution is equal to pulse length. The transversal resolution is half of the wavelength or half of the diameter of the probe. The single frequency holography is optimal to image planar reflectors. When planar reflectors are inclined with respect to the aperture they can best be imaged with SAFT or multifrequency holography. Some images based on the inspections with SAFT carried out by IzfP in Saarbrcken are shown. The specimens to be tested were supplied by the Technical Research Centre of Finland (VTT). The results were in good agreement with earlier measurements with surface wave method.

    AB - The main principles and restrictions of the numerical focusing such as the acoustical holography and the synthetic aperture focusing technique (SAFT) are described. In the holography the ultimate lateral resolution is half of the wavelength. The longitudinal resolution is poor. With SAFT the longitudinal resolution is equal to pulse length. The transversal resolution is half of the wavelength or half of the diameter of the probe. The single frequency holography is optimal to image planar reflectors. When planar reflectors are inclined with respect to the aperture they can best be imaged with SAFT or multifrequency holography. Some images based on the inspections with SAFT carried out by IzfP in Saarbrcken are shown. The specimens to be tested were supplied by the Technical Research Centre of Finland (VTT). The results were in good agreement with earlier measurements with surface wave method.

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    KW - focusing

    KW - holography

    M3 - Report

    SN - 951-38-2743-7

    T3 - Valtion teknillinen tutkimuskeskus. Tiedotteita

    BT - Numerical focusing of ultrasound

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    ER -

    Lahdenperä K. Numerical focusing of ultrasound. Espoo: VTT Technical Research Centre of Finland, 1986. 21 p. (Valtion teknillinen tutkimuskeskus. Tiedotteita; No. 642).