Patent ID: 7239134

Claim:
An apparatus for excluding ferromagnetic objects from a safe zone, comprising: at least one applied magnetic field source; at least one pair of sensors arranged and connected as a gradiometer, each said sensor of said at least one pair being adapted to sense a magnetic field of an object, said magnetic field of said object being an induced magnetic field caused by magnetization of said object by said at least one applied magnetic field source; a processor adapted to interpret signals from said at least one pair of sensors; and a structure on which said at least one pair of sensors and said at least one applied magnetic field source are mounted, said structure being adapted to selectively position said at least one pair of sensors and said at least one applied magnetic field source in proximity to one or more selected areas of interest, while selectively orienting said at least one pair of sensors and said at least one applied magnetic field source so that the axis of the magnetic field is arranged along a selected axis adjacent each said area of interest, and while selectively moving said at least one pair of sensors and said at least one applied magnetic field source along said selected axis adjacent each said area of interest.