Method and apparatus for defect detection

摘要

A method and apparatus for detecting defects on a metal surface, particularly the inside surface of tubular articles. Resonance tuned electrical circuits and associated eddy current coils are used to produce an eddy current in the surface to be inspected for surface defects. Voltage changes resulting from circuit loss changes in any one of the circuits caused by the presence of defects in the metal surface adjacent to one of the coils is detected and a related output signal is produced. <IMAGE>