title: Nondestructive evaluation of incipient corrosion in a metal beneath paint by second-harmonic tomography.
abstract: A second-harmonic optical scanning imaging method for nondestructive evaluation of corrosion of painted metals is demonstrated. Two-dimensional images of the sectional structure from a sample of painted metal with corrosion were obtained by detection of second-harmonic generation (SHG). The second-harmonic signals generated from paint, corrosion, and metal can be spatially imaged in ~10-mum sliced subsurface layers. Corroded metal layers covered with paint are found to have more intensity variation than normal polished metal. The spatial mapping of the second-harmonic signals shows depth differentiation of paint, corrosion, and metal surfaces. The depth of corrosion beneath the paint can be measured from the SHG images.
authors: J
authors: J
authors: Ying
authors: F
authors: F
authors: Liu
authors: P P
authors: PP
authors: Ho
authors: R R
authors: RR
authors: Alfano