Paper
10 October 2003 Advances in thermographic NDT
Author Affiliations +
Abstract
Active thermography has gained broad acceptance as a Nondestructive Test (NDT) method for numerous in-service and manufacturing applications in the aerospace, power generation and automotive industries. However, the diffusive nature of the heat conduction process renders imaging of subsurface structures susceptible to blurring and degradation of the signal with feature depth. Although this constraint is fundamental, significant improvements in blur reduction, depth sensitivity and detection of subtle features have been achieved. These improvements have been facilitated by a Thermal Signal Reconstruction method, based on a least squares polynomial fit of the logarithm of the time history of each pixel. The process separates temporal and spatial nonuniformity noise components in the image sequence, and significantly reduces temporal noise. Time derivative images created from the reconstructed data allow detection of subsurface defects at earlier times in the sequence than conventional contrast images, significantly reducing undesirable blurring effects, and facilitating detection of low thermal contrast features that may not be detectable in the original data sequence.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Steven M. Shepard "Advances in thermographic NDT", Proc. SPIE 5074, Infrared Technology and Applications XXIX, (10 October 2003); https://doi.org/10.1117/12.498157
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Cited by 17 scholarly publications.
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KEYWORDS
Thermography

Infrared cameras

Cameras

Image processing

Nondestructive evaluation

Infrared imaging

Signal to noise ratio

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