Crack imaging by scanning laser-line thermography and laser-spot thermography

T Li, Darryl P Almond, D Andrew S Rees

Research output: Contribution to journalArticle

69 Citations (Scopus)
184 Downloads (Pure)

Abstract

The thermographic images of laser-heated spots or lines are perturbed by nearby cracks, providing NDE techniques for crack detection. Scanning with a laser line, rather than a laser spot, results in a substantial reduction in inspection time. 3D finite difference modelling results are presented that show the sensitivity of the laser-line thermography technique to cracks of varying lengths, depths and openings. A novel crack imaging technique is presented that is based on assembling the second spatial derivative thermal images of a scanned laser line. Experimental results show the new technique to image cracks with openings as small as a few micrometres. The scanning time of the laser-line thermography technique is shown to be over an order of magnitude smaller than that of the laser-spot thermography technique whilst producing crack images of similar quality.
Original languageEnglish
Article number035701
Number of pages14
JournalMeasurement Science and Technology
Volume22
Issue number3
Early online date1 Feb 2011
DOIs
Publication statusPublished - Mar 2011

Keywords

  • cracks
  • nondestructive evaluation
  • laser
  • thermography

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