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THz-ToF techniques for the detection of inherent discontinuities in dielectric materials based on a SAFT – and an optical layer reconstruction algorithm

  • Electromagnetic waves with frequencies between 0.1 and 10 THz are described as THz-radiation (T-ray). The ability to penetrate dielectric materials makes T-rays attractive to reveal discontinuities in polymer and ceramic materials. THz-Time Domain Spectroscopy Systems (THz-TDS) are available on the market today which operates with THz-pulses transmitted and received by optically pumped semiconductor antennas. In THz-TDS the travelling time (ToF) and shape of the pulse is changed if it interacts with the dielectric material and its inherent discontinuities. A tomogram of the object under the test can be reconstructed from time of flight diffraction (ToFD) scans if a synthetic focusing aperture (SAFT) algorithm is applied. Otherwise, planar discontinuities like cracks in plastics or delaminated layers in composites can be abstracted as layers located at any angle in relation to the outer sample surface direction. A tomogram from the scanned sample can then be reconstructed in case theElectromagnetic waves with frequencies between 0.1 and 10 THz are described as THz-radiation (T-ray). The ability to penetrate dielectric materials makes T-rays attractive to reveal discontinuities in polymer and ceramic materials. THz-Time Domain Spectroscopy Systems (THz-TDS) are available on the market today which operates with THz-pulses transmitted and received by optically pumped semiconductor antennas. In THz-TDS the travelling time (ToF) and shape of the pulse is changed if it interacts with the dielectric material and its inherent discontinuities. A tomogram of the object under the test can be reconstructed from time of flight diffraction (ToFD) scans if a synthetic focusing aperture (SAFT) algorithm is applied. Otherwise, planar discontinuities like cracks in plastics or delaminated layers in composites can be abstracted as layers located at any angle in relation to the outer sample surface direction. A tomogram from the scanned sample can then be reconstructed in case the interactions of electromagnetic pulses with the existing inherent interfaces are detectable and a model is assumed which describes the device under the test as multilayer structure composed of thin layers with different dielectric properties. A short description of both the SAFT – and Optical Layer algorithm for the reconstruction of the inherent structure is initially given. Measurements on representative samples with a variety of artificially produced small and large scale. Reconstructed tomograms are presented to discuss and evaluate the benefits and limits of the two different reconstruction approaches.zeige mehrzeige weniger

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Metadaten
Autoren/innen:Holger Spranger, Jörg Beckmann, Rainer Boehm
Dokumenttyp:Beitrag zu einem Tagungsband
Veröffentlichungsform:Graue Literatur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):DGZfP-Proceedings
Jahr der Erstveröffentlichung:2016
Organisationseinheit der BAM:8 Zerstörungsfreie Prüfung
8 Zerstörungsfreie Prüfung / 8.3 Radiologische Verfahren
8 Zerstörungsfreie Prüfung / 8.4 Akustische und elektromagnetische Verfahren
Veröffentlichende Institution:Bundesanstalt für Materialforschung und -prüfung (BAM)
Jahrgang/Band:158
Erste Seite:1
Letzte Seite:10
DDC-Klassifikation:Naturwissenschaften und Mathematik / Chemie / Analytische Chemie
Freie Schlagwörter:THz SAFT Optical layer reconstruction
Themenfelder/Aktivitätsfelder der BAM:Analytical Sciences
Veranstaltung:19th World Conference on Non-Destructive Testing 2016
Veranstaltungsort:Munich, Germany
Beginndatum der Veranstaltung:13.06.2016
URN:urn:nbn:de:kobv:b43-365866
ISBN:978-3-940283-78-8
Verfügbarkeit des Dokuments:Datei für die Öffentlichkeit verfügbar ("Open Access")
Lizenz (Deutsch):License LogoCreative Commons - Namensnennung-Keine Bearbeitung
Datum der Freischaltung:21.06.2016
Referierte Publikation:Nein
Schriftenreihen ohne Nummerierung:Wissenschaftliche Artikel der BAM