Detection of Voids and Contaminants in Polyethylene Insulated Cable Utilizing a Fir Laser Beam

A prototype cable inspection instrument for the detection of defects in PE and XLPE insulation is described. The operating principle involves the Miescattering of laser illumination at submillimeter wave- lengths that match the size range of defects of interest. This instrument is capable of detecting defects as small as 50 vm inside the insulation, and providing a realtime cable inspection with essentially full coverage during manufacturing. Detectable defects include voids and contaminants within the insulation, and protrusions and skips in the conductor shield. Other applications of this technology will also be discussed.