Application of data fusion to thermal wave imaging with lockin thermography

Abstract

Lockin-thermography has become a valuable tool for non-destructive testing (NDE) of materials since it provides in a short time phase images of hidden defects. However, besides finding defects it is important to derive more information to characterise them. We present an innovative way to combine phase images obtained at different lockin-frequencies by using scatter plots. Besides defect depths this method of data fusion allows for feature extraction like thermal wave reflection coefficient, local planarity, and edge effects due to the lateral heat flow caused by them. The extracted features can be traced back to the original image. © 2010 IOP Publishing Ltd.