Non-destructive inspection of copper corrosion via coherent terahertz light source

In order to investigate the infrared activities of corrosion products of copper in terahertz (THz) frequency band, THz absorption spectra of copper (I) oxide (Cu₂O) and copper (II) oxide (CuO) powders are measured. In view of the practical application for nondestructive inspection of copper wire deterioration, THz reflectance spectra of copper conductive wires with and without oxidization were also measured. THz spectroscopy results have shown some clear specific absorption bands in 1-5THz region, and the THz reflection spectra have revealed clear reflection intensity difference at around 1.7THz band between corroded and notcorroded copper wires. It is also shown that the surrounding polyethylene (PE) of copper electric wire is very transparent for THz wave, thus non-destructive inspection of the corrosion status of copper wire surrounded by the invisible PE insulator can be possible by using THz wave.