Abstract: A method and an apparatus are disclosed, to screen patients or other areas for ferromagnetic objects, particularly for use intra-operatively in an operating room. The device comprises at least one magnetic field source, at least one magnetic gradiometer, and the associated electronics. The field source and the gradiometer are supported by an arm structure which can be manipulated to position the field source and the gradiometer at one or more positions near areas of interest, such as areas on a patient or other subject, and to orient the field source and the gradiometer so that the axis of the magnetic field is arranged along three different non-parallel, non-coplanar, axes to ensure detection of any ferromagnetic object regardless of its shape and orientation. The device can be manipulated to place the sensor arrays in close proximity to selected parts of a subject's body, for screening purposes.

Abstract: A ferromagnetic detection pillar having one or more applied magnetic field sources and one or more magnetic field sensors, with the magnets and sensors arranged and adapted to detect a ferromagnetic threat object on one side of the pillar. A detection device, such as a motion detector or infrared detector, is also provided, to detect the presence of an object on a selected side of the pillar. A single free-standing pillar can be used, or two or more free-standing pillars can be arranged to constitute a variable aperture detection portal. Single sensors or multiple-sensor configurations can be used.

Abstract: A ferromagnetic detection pillar having one or more applied magnetic field sources and one or more magnetic field sensors, with the magnets and sensors arranged and adapted to detect a ferromagnetic threat object on any side of the pillar. A single free-standing pillar can be used to provide protection in an MRI facility, or two or more free-standing pillars can be arranged to constitute a variable aperture detection portal. Single sensors or multiple-sensor configurations can be used.

Abstract: An MRI pre-screening apparatus having an applied field source and a saturation-resistant magnetoresistive sensor, wherein the applied field source is sufficiently strong to magnetize any anticipated ferromagnetic threat object but the sensor is not saturated by the applied magnetic field. The sensor can be made saturation-resistant by being constructed of non-magnetic materials. A flux concentrator can be implemented to increase sensor sensitivity.

Abstract: A method and apparatus for enhancing detection of a ferromagnetic threat object by magnetizing the threat object with a separate magnetic field, prior to scanning of the subject by a ferromagnetic-detecting sensor system.

Abstract: A magnetic hubbing assembly for engaging and rotating the hub of a removable recording medium has a segmented hub and a hubbing magnet including four or more poles. The hubbing magnet is ring-shaped and the hub is a high permeability SiFe metal. Segments of the hub are equal in number to the number of poles of the magnet.

Abstract: A flux-responsive magnetic head having a transducer gap also has first and second back gaps across which, respectively, are first and second thin film magnetoresistive elements. The elements have similarly oriented magnetization vectors and, as such, the magnetoresistive elements are differentially responsive to flux entering said transducer gap. Spurious fields, however, have no differential effect on the resistances of the magnetoresistive elements. In a preferred form of the invention, an additional, similar working, pair of magnetoresistive elements is employed across the back gaps, such additional elements not only providing increased signal response, but also serving as keepers for the first pair of magnetoresistive elements.