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Laser Thermography – Evolution from a highly specialized into a versatile tool for NDE

  • Laser thermography has its roots in the late-1960s when Kubiak first used a focused light source to raster-scan a specimen containing surface breaking cracks and employed an infrared detector to monitor the blocking effect of the cracks on the heat flow. Nowadays, this technique has evolved into the flying-spot laser thermography. In the mid-1970s, when Rosencwaig and Gersho worked out the theory for the photoacoustic effect, they laid the foundation for the development of the photothermal testing methodology. The decisive difference to the flying-spot technique is that in the photothermal methodology, a high-frequency modulated laser beam is used, which explicitly uses the concept of the thermal wave. Starting in the 1980s, infrared cameras came into play and enabled full-field thermal imaging, but this time, slow thermal light sources were used. Today, flash lamps (pulsed planar heating) and halogen lamps (modulated planar heating) have been established as the standard lightLaser thermography has its roots in the late-1960s when Kubiak first used a focused light source to raster-scan a specimen containing surface breaking cracks and employed an infrared detector to monitor the blocking effect of the cracks on the heat flow. Nowadays, this technique has evolved into the flying-spot laser thermography. In the mid-1970s, when Rosencwaig and Gersho worked out the theory for the photoacoustic effect, they laid the foundation for the development of the photothermal testing methodology. The decisive difference to the flying-spot technique is that in the photothermal methodology, a high-frequency modulated laser beam is used, which explicitly uses the concept of the thermal wave. Starting in the 1980s, infrared cameras came into play and enabled full-field thermal imaging, but this time, slow thermal light sources were used. Today, flash lamps (pulsed planar heating) and halogen lamps (modulated planar heating) have been established as the standard light sources for the specific regimes of pulsed and lock-in thermography. Only recently, the availability of novel technologies – fast and high-resolution infrared cameras, innovative brilliant laser sources and high-performance data acquisition and processing technology – has enabled a paradigm shift from the separated photothermal and thermographic methodologies to a versatile tool for NDE that combines both approaches. In addition, the heating can also be spatially structured using laser arrays. This new degree of freedom allows the development of completely new thermography NDE methods. In the talk, we present current activities with kilowatt-class high-power laser sources for advanced flying-spot, pulsed, lock-in and laser-projected thermography.zeige mehrzeige weniger

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Autor*innen:Philipp Myrach
Koautor*innen:Erik Thiel, Florian Jonietz, Taarna Studemund, Mathias Ziegler
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2017
DDC-Klassifikation:Naturwissenschaften und Mathematik / Chemie / Analytische Chemie
Freie Schlagwörter:Laser; Lock-in; Thermografie; VCSEL; Zerstörungsfreie Prüfung; photothermisch
Veranstaltung:NDE 2017
Veranstaltungsort:Chennai, India
Beginndatum der Veranstaltung:14.12.2017
Enddatum der Veranstaltung:16.12.2017
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:14.12.2017
Referierte Publikation:Nein
Eingeladener Vortrag:Nein
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