A New Capacitive Imaging Technique for NDT

A new technique for NDT has been developed which is capable of imaging a wide range of materials and structures, ranging from insulators to metallic conductors. The approach, known as Capacitive Imaging, uses electrode arrays in air to produce an AC electric field distribution within the material. Scanning the electrodes over the material causes a change in the field distribution, and hence changes in output voltage. Capacitive coupling allows the technique to work on a wide variety of material properties, without the disadvantages associated with conventional eddy current and potential drop methods. Images are presented of carbon fibre composite materials, Perspex and metals, illustrating the range of application in NDT.