Abstract:
Infrared thermography is a well-established technique for the nondestructive characterisation of various materials. This technique relies
on the analysis of acquired temperature profile over the test sample
to evaluate the presence of surface and sub-surface anomalies within
the material. Over past decade coded thermal excitation schemes
and associated post processing (signal/video processing) schemes
have gained vital attention in infrared thermographic community in
various fields. However, in thermal non-destructive testing the usage
of coded excitations are still relatively uncommon. This paper explores
the feasibility of using complementary Golay coded excitation in
active thermography. The newly developed technique is shown to
be effective in increasing temporal signal to noise ratio by suppressing
side lobes of the compressed pulse. The present experimental
investigation emphasises the defect detection capabilities of Golay
coded thermal wave imaging to characterise a carbon fibre reinforced
plastic material having blind holes and inclusions as defects. An
investigation of spatial signal to noise ratio is also presented.
