Abstract: According to some embodiments of the invention, a magnetic sensor having a track width of greater than about 50 millimeters is provided. The magnetic sensor is adapted to detect a magnetic feature and produce a linear, analog output in response to the magnetic feature. The analog output is along a single data channel.

Abstract: According to some embodiments of the invention, a magnetic sensor having a track width of greater than about 50 millimeters is provided. The magnetic sensor is adapted to detect a magnetic feature and produce a linear, analog output in response to the magnetic feature. The analog output is along a single data channel.

Abstract: According to some embodiments of the invention, a magnetic sensor having a track width of greater than about 50 millimeters is provided. The magnetic sensor is adapted to detect a magnetic feature and produce a linear, analog output in response to the magnetic feature. The analog output is along a single data channel.

Abstract: According to some embodiments of the invention, a magnetic sensor having a track width of greater than about 50 millimeters is provided. The magnetic sensor is adapted to detect a magnetic feature and produce a linear, analog output in response to the magnetic feature. The analog output is along a single data channel.

Abstract: A method and apparatus for detecting ferromagnetic threat objects on a recumbent patient, including magnetizing/sensing stations having mutually orthogonal magnetizing axes. Two magnetizing/sensing stations can be used, but three or more are preferred. The magnetizing/sensing stations are arranged on a table-like mounting structure providing a path for the patient to roll beneath the magnetizing/sensing stations on a gurney. Three additional magnetizing/sensing stations can be provided on either side, or on each side, of the gurney path, at the same height as the patient.

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: According to some embodiments of the invention, a magnetic sensor having a track width of greater than about 50 millimeters is provided. The magnetic sensor is adapted to detect a magnetic feature and produce a linear, analog output in response to the magnetic feature. The analog output is along a single data channel.

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 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 particulate magnetic recording media wherein the magnetic particles are substantially spherical. The spherical particle shape makes possible a media which is magnetically isotropic, well dispersed and low in noise, and free of magnetically inferior broken particles.

Abstract: In the simplest embodiment of the invention, the apparatus holds the edge of the magnetized film to be measured close to, and above, a linearly biased magnetoresistive (MR) element. Magnetic poles appearing at the magnetic discontinuity at the edge of the film generate a magnetic field which is incident on the MR element, and which results in a measurable change in the element's resistivity. In a preferred embodiment, a pair of MR elements are placed so that they are both linearly biased by a magnet; only one of the MR elements being in close proximity to, and influenced by the magnetic field emanating from the edge of the magnetized film. The second MR element, selected for matched characteristics with the first MR element, is located out of the field of the magnetized film, but still subject to the same temperature environment and field noise as the first MR element.

Abstract: A magnetic fingerprint image is implemented by having the user coat his finger tip with a magnetic powder and transferring the powder particles to the document surface. The magnetic fingerprint image is then covered by a thin, non-removable, plastic film that is optically opaque but is magnetically transparent. The print is scannable by a magnetic head whose output signal consists of a sequence of electrical waveforms characteristic of the ridges and depressions that define the fingerprint. The fingerprint image may be angularly rotated about an axis perpendicular to the plane of the print prior to fixing the fingerprint image onto the document. Because the image is covered by the opaque film, the outside observer cannot determine the angular orientation of the image relative to the document edge. A magnetically encoded "address" readable by the scanning magnetic head before it reads the magnetic fingerprint itself, informs the scanning apparatus of the fingerprint angular orientation.

Abstract: A magneto-optic layer of bismuth-garnet deposited on a thin transparent substrate is utilized in viewing very low amplitude magnetic field patterns. When subjected to a magnetic field perpendicular to the layer, the layer lowers its magnetic energy by breaking up into a series of reversed domains called meander patterns. As the magnetic fields to be viewed are too low in amplitude, (approximately equal to, or less than 1 Oe), to directly modify the meander pattern, the magneto-optic layer is excited with an AC magnetic field of more than 100 Oe which is then slowly reduced to zero; (a small DC bias field is simultaneously applied to control the background of the viewed field, and to cancel the earth's field). This causes the anhysteretic transfer of the pattern of the low amplitude field onto the magneto-optic layer, with the resultant meander pattern replicating the low amplitude field pattern.

Abstract: In order to measure the magnetic saturation flux density of a sample material, a first and a second sample holder are symmetrically position on either side of a cylindrical permanent magnet. Coils are placed around the sample holders and the permanent magnet is rotated. The signals induced in the coils in the absence of a magnetic material in one of the sample holders are applied to an amplifier/meter in such a manner as to provide a null signal. When a sample is placed in one of the sample holders, the magnetic saturation flux density can be measured. The present device finds particular application to determining the concentration of a magnetic particles dispersed in a fluid.

Abstract: A magnetic assembly for detection and authentication of magnetic documents. The magnetic assembly includes a permanent magnet (PM), first and second magnetically soft high permeability pole pieces shaped to form a tapered, variable gap size magnetic circuit with the permanent magnet. The PM is located at a first gap between the first and second pole pieces. A magnetoresistive (MR) sensing element is located at or near the center of a second gap between said first and second pole pieces. The second gap and MR sensing element are proximate a magnetic document to be sensed.

Abstract: A method is disclosed to provide a unique indicator of authenticity of currency or a document, optically responsive to a local magnetic field and which employs material difficult to duplicate. The indicator is in the form of magnetic viewing material added to the document either by adherence of a patch or strip of the material, or by printing it directly onto the document's surface. The basic ingredient of the magnetic viewing material is a multitude of minute micro-capsules, each having tiny nickel flakes suspended in a viscous fluid encapsulated by a tough, transparent plastic shell. A layer consisting of these micro-capsules has the property that the planes of the nickel flakes will align themselves in the direction of an applied magnetic field. If the field is perpendicular to the layer, the flakes will be seen edge on and will reflect a minimum amount of light.

Abstract: A low Curie temperature magnetic material (such as chromium dioxide) is used as a magnetic pigment to validate valuable documents such as banknotes. CrO.sub.2 is very black in color and is an excellent magnetic recording medium, and has a Curie temperature of 128 degrees C. A region of a banknote or other valuable document is printed with an ink containing CrO.sub.2 particles. To test the validity of the document, the magnetic media on the document is subjected to magnetic field having a characteristic spatial pattern; the field of a permanent magnet having alternating magnetic poles is a convenient field source. The banknote, and its magnetized region, is then brought to a temperature of at least 128 degrees C, which is readily accomplished by use of a heat lamp, and the region inspected with a magnetic field sensitive optical reader. If it is a genuine bill whose magnetized region was printed with an ink containing CrO.sub.

Abstract: A magnetic assembly for detection and authentication of magnetic documents. The magnetic assembly includes a permanent magnet (PM), first and second magnetically soft high permeability pole pieces shaped to form a tapered, variable gap size magnetic circuit with the permanent magnet. The PM is located at a first gap between the first and second pole pieces. A magnetoresistive (MR) sensing element is located at or near the center of a second gap between said first and second pole pieces. The second gap and MR sensing element are proximate a magnetic document to be sensed. An electrical conductor is adjacent to the MR sensing element, but is electrically insulated therefrom.

Abstract: A detection system for detecting and/or verifying the magnetic properties of the magnetic ink layer on common printed or copied documents includes, in order of interaction with the magnetic ink of a Document, a saturation record head, a saturation read head, a non-saturation record head, and a non-saturation read head. The disclosed method of operation is equivalent to the normal testing of the magnetic layer of a Document, but eliminates the need for an erase magnet.

Abstract: A silver halide photographic element comprising a support having thereon at least one light-sensitive silver halide emulsion layer and a transparent magnetic recording layer on the substrate, the transparent magnetic recording layer having barium ferrite platelet particles in a transparent binder, the barium ferrite platelet particles being aligned such that the easy axis of the particles is parallel to the substrate.