Hilbert transform-based pulse compression approach to infrared thermal wave imaging for sub-surface defect detection in steel material

Infrared thermal non-destructive testing (TNDT) is a fast, reliable and non-contact inspection approach for the evaluation of various solid materials. Of various TNDT approaches, non-stationary thermal wave imaging (NSTWI) techniques with a pulse compression approach have gained wide acceptance due to their merits, such as a higher defect detection sensitivity and resolution compared to conventional TNDT techniques. The present work highlights the applicability of the NSTWI technique for defect detection in a mild steel sample. Further defect detection capabilities of the time domain phase approach have been presented.