A magnetic imager 10 includes a generator 18 for practicing a method of applying a background magnetic field over a concealed object, with the object being effective to locally perturb the background field. The imager 10 also includes a sensor 20 for measuring perturbations of the background field to...http://www.google.es/patents/US5650725?utm_source=gb-gplus-sharePatente US5650725 - Magnetic imager and method
