Signal to Noise Ratio Threshold in Active Thermography

Jürgen Gruber, Karl-Heinz Gresslehner, Jakov Sekelja, Günther Mayr, Günther Hendorfer

Research output: Chapter in Book/Report/Conference proceedingsConference contribution


In this study an approach to determine the Signal to Background Contrast, by using a threshold level as a suitable measure for Active Thermography is given. Carbon Fiber Reinforced Plastic specimen with artificial defects in random positions and depths were manufactured and analysed. These artificial defects were fabricated by using folded Teflon foil pieces to enclose a small amount of air, which acts as a delamination. Measurements were carried out in reflection as well as in transmission mode with data analysis in time and frequency domain. For thermal excitation two high power flash lamps were used. After processing of the temperature-time history diffusion time images as well as phase images were given to different inspectors to search for defects and mark them. From their results a hit/miss matrix was derived and a Probability of Detection analysis was carried out.
Original languageEnglish
Title of host publicationProceedings 6th International symposium for NDT in Aerospace
Number of pages8
Publication statusPublished - 2014
Event6th Symposium for NDT in Aerospace - Madrid, Spain
Duration: 12 Nov 201414 Nov 2014


Workshop6th Symposium for NDT in Aerospace
Internet address


  • infrared testing (IRT)
  • active thermography
  • signal to noise ratio (SNR)
  • probability of detection (POD)
  • carbon fiber reinforced plastics (CFRP)


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