Principal Component Thermography 

PCTPrincipal Component Thermography is another technique of active thermography in which principal component analysis is used to enhance the visibility of defects in the data collected. In pulsed phase thermography, PPT (see last month’s ‘What the Hec?!’), a Fourier transform is used to convert the data in the thermal images to a phase-frequency space, but this is not always the best method of analysing a pulsed signal. PCT also transforms the data in the thermal images, extracting spacial and time information in a compact manner. The result is a matrix where the columns contain the time data and the rows contain the spatial data.

For more information on an application of PCT see:
K E Cramer and W P Winfree, ‘The application of infrared thermographic inspection techniques to the Space Shuttle thermal protection system’, NASA, Langley Research Center. Available from: http://ntrs.nasa.gov/search.jsp?R=20050241763

What the hec?! articles are not intended to be the definitive account on the topic or acronym in question. Readers’ comments and contributions are welcomed. Email: ndtnews@bindt.org