Patent ID: 6731968
Filing Date: 2004-05-04
Classification: A61B,G01R,H05K

Abstract:
An apparatus comprising:an enclosure having a wall defining an interior of the enclosure, the wall comprising a layer of a magnetically permeable material disposed such that there is no layer of an electrically conductive material located closer to the interior of the enclosure than the layer of the magnetically permeable material; a background-field magnetometer within the enclosure and having a background-field magnetometer output signal; an electrical coil structure within the interior of the enclosure and producing a magnetic output field responsive to an electrical coil input; a controllable electrical current source having a current source output in communication with the electrical coil input, and a current source command signal input; and a background-field-reducing feedback controller having a controller input responsive to the background-field magnetometer output signal, and a controller output in communication with the current source command signal input.