Characterizing defects in materials with fusion of thermography and shearography

Abstract

Thermography and shearography are optical techniques for detecting and characterizing subsurface defects in structures. Both techniques possess unique advantages and abilities, as well as limitations, based on their distinct mechanisms. In this study, the feasibility in fusion of thermography and shearography is explored. Thermal excitation is selected to induce temperature variation and out-of-plane deformation on the object surface, acquiring the shearography phase maps and thermography image sequence simultaneously. Infrared images are dealt with by the Fourier phase analysis incorporate with an edge-aware filter. Fusion of the detecting images is obtained by performing a projective transform between each pair of the thermography and shearography images. Subsequently, both thermography and shearography images are separated into detail and background images. The fused image is reconstructed from the detail and background images by applying a weighting function. Experiments have indicated that the proposed method is effective in identifying defects by combining two image-based NDT methods.