Quantifying Surface Deformation With the Edge of Light-Enhanced Visual Inspection

Edge of light (EOL) is a rapid enhanced visual inspection technique developed by the Institute for Aerospace Research, National Research Council Canada. One application of interest is the inspection of aircraft lap joints for pillowing deformation caused by hidden corrosion. The EOL technique provides an intuitive result, which is a representation of surface topography. However, a quantitative interpretation of the inspection results is still a challenge. In this paper, the quantification of surface deformation is investigated by using a laser-displacement sensor as a calibration tool. A procedure that implements the reconstruction of the deformed surface from EOL scanning is proposed. Experimental results obtained from a pillowing simulator and a service-retired aircraft lap joint are presented in this paper to demonstrate the effectiveness of the proposed approach.