Observation of damage in insulated copper cables by THz imaging

•Internal copper wires covered with insulating polyethylene have been imaged by THz.•The disconnection of the internal wire was detected.•THz was successfully applied to non-destructive inspection of copper cables.

A novel non-destructive inspection method using terahertz waves for the detection of broken wires in copper cables shielded by insulating polymer opaque in the visible and near infrared light region is presented. Terahertz reflection imaging, using a 0.14 THz IMPATT oscillator and a Schottky barrier detector, was applied to insulated copper cables that had been artificially damaged. The internal insulated wires embedded in the opaque polyethylene can be clearly visualized using THz radiation. It was shown that a gap in a wire can be detected by a decrease in the intensity of the reflected signal where the size of the gap is greater than the wavelength of the oscillator.