Remote optical non-destructive inspection techniques for metal and composite structures

This paper presents a laser based non-destructive inspection technique which is purely non-contact. An acoustic device is used to remotely excite the material under inspection while a scanning laser vibrometer is employed to measure the resulting vibrations. The test materials, mostly aluminum or composite aircraft structures, have been successfully inspected from a standoff distance of at least a meter. The NDI system clearly shows the defect locations overlaid on the images of the test objects for ease of the end user. Metal and composite delamination and subsurface corrosion in aluminum structures are among the defects that were detected.