Abstract: A planar MRI system is disclosed. The system has an open magnet configuration that produces a magnetic field having a remote region of substantial magnetic field homogeneity. Spatial encoding gradient coils and a rf coil provide MRI data for image reconstruction. The open magnet configuration has a ferromagnetic core with a substantially planar core surface layer and a longitudinal axis, and a unipolar current wire pair on a side of the ferromagnetic core adjacent the planar core surface layer. The wire pair is separated along the longitudinal axis and extends in a direction substantially perpendicular to the axis and substantially parallel to the planar core surface layer. The current wire pair provides a magnetic field having a maximum between the current wire pair along a direction perpendicular to the planar core surface layer and in the remote region of substantial magnetic field homogeneity.

Abstract: A planar MRI system is disclosed. The system has an open magnet configuration that produces a magnetic field having a remote region of substantial magnetic field homogeneity. Spatial encoding gradient coils and a rf coil provide MRI data for image reconstruction. A first magnet system having a first ferromagnetic core and a first longitudinal axis with a first pair of coils around the first ferromagnetic core and spaced apart along the first longitudinal axis is located orthogonal to and in substantially the same plane as a second magnet system having a second ferromagnetic core and a second longitudinal axis with a second pair of coils around the second ferromagnetic core and spaced apart along the second longitudinal axis. The open magnet configuration preferably has a ferromagnetic core with a substantially planar core surface layer and a longitudinal axis, and a unipolar current wire pair on a side of the ferromagnetic core adjacent the planar core surface layer.

Abstract: A planar MRI system is disclosed. The system has an open magnet configuration that produces a magnetic field having a remote region of substantial magnetic field homogeneity. Spatial encoding gradient coils and a rf coil provide MRI data for image reconstruction. A first magnet system having a first ferromagnetic core and a first longitudinal axis with a first pair of coils around the first ferromagnetic core and spaced apart along the first longitudinal axis is located orthogonal to and in substantially the same plane as a second magnet system having a second ferromagnetic core and a second longitudinal axis with a second pair of coils around the second ferromagnetic core and spaced apart along the second longitudinal axis. The open magnet configuration preferably has a ferromagnetic core with a substantially planar core surface layer and a longitudinal axis, and a unipolar current wire pair on a side of the ferromagnetic core adjacent the planar core surface layer.

Abstract: A planar MRI system is disclosed. The system has an open magnet configuration that produces a magnetic field having a remote region of substantial magnetic field homogeneity. Spatial encoding gradient coils and a rf coil provide MRI data for image reconstruction. The open magnet configuration has a ferromagnetic core with a substantially planar core surface layer and a longitudinal axis, and a unipolar current wire pair on a side of the ferromagnetic core adjacent the planar core surface layer. The wire pair is separated along the longitudinal axis and extends in a direction substantially perpendicular to the axis and substantially parallel to the planar core surface layer. The current wire pair provides a magnetic field having a maximum between the current wire pair along a direction perpendicular to the planar core surface layer and in the remote region of substantial magnetic field homogeneity.

Abstract: A magnet resonance imaging system is described having an open magnet structure that provides a remote region of background field homogeneity for imaging that is open and accessible. The system includes spatial encoding gradient coils and a rf coil. The open magnet structure has an planar active shimming coil array that provides a remote region of enhanced field homogeneity with open geometry for easy accessibility to a patient. Preferably, the active planar shimming coil array has one or more pair of current loops arranged and constructed in a plane separating the open magnet structure from the remote region, a first loop having current in a first direction to provide a magnetic flux (i.e., magnetization vector) away from the plane and a second loop having current in the opposite direction to provide a magnetic flux (i.e., magnetization vector) toward the plane.

Abstract: A magnet resonance imaging system is described having an open solenoidal magnet structure that provides a remote region of background field homogeneity for imaging that is open and accessible. The system includes spatial encoding gradient coils and a rf coil. The open magnet structure has a pair of primary solenoidal coils and a bias coil system located within the primary coil geometry. The primary and bias coils emit a total additive flux in an imaging region to generate a resulting background magnetic field profile that provides a remote region of substantial field homogeneity with open geometry for easy accessibility to a patient.

Abstract: A magnet resonance imaging system is described having an open magnet structure that provides a remote region of background field homogeneity for imaging. The system includes spatial encoding gradient coils and an rf coil. The open magnet structure has a primary magnet with two primary pole pieces connected by a primary ferromagnetic core for internal flux. Each primary pole piece has a surface facing away from the primary magnet. Located between the two primary pole pieces is a bias magnet having two bias pole pieces connected by a bias ferromagnetic flux pathway for internal flux. The bias magnet has polarity opposite to the primary magnet. Each bias pole piece has a surface facing away from the bias magnet and in a direction the same as the surfaces of the primary pole pieces. Superposition of the magnetic fields of the primary magnet and bias magnet provide a region of substantial background field homogeneity remote from the magnets in said direction.

Abstract: A magnetic resonance imaging (MRI) probe having an external background magnetic field B.sub.o is described. The probe has a primary magnet having a longitudinal axis and an external surface extending in the axial direction and a rf coil surrounding and proximal to the surface. The magnet provides a B.sub.o field having an external region of substantial homogeneity proximal to the surface. Preferably, the B.sub.o field is provided by two magnets spaced axially and in axial alignment and wherein said region of homogeneity intersects a plane located between the magnets and perpendicular to the axis. For MR imaging, surrounding the primary magnet are r-, z- and .o slashed.-gradient coils to provide spatial encoding fields.

Abstract: An MRI imaging device has a cylindrical magnet configuration, gradient coils and an Rf coil. The magnet has a primary and a secondary electromagnet on the same longitudinal center axis but spaced apart along the axis. Each electromagnet is a coil located within a flux guiding member preferably having a cylindrical structure closed at one end. The electromagnets provide a static magnetic field having substantial homogeneity in a central air gap A.sub.G extending from within the primary electromagnet coil axially beyond the primary coil toward the secondary electromagnet coil.

Abstract: An MRI system has a magnet configuration that provides access for a surgeon or other personnel to perform procedures on a patient under support of real time MRI image. The magnet system uses a plurality of C-shape solenoidal magnets oriented to form an imaging volume in a central region of the magnets so that the magnetic flux from each magnet contributes to the magnetic field in the imaging volume. The configuration provides a high strength field in the imaging volume. The MRI system has a gradient coil for providing a magnetic field gradient in the imaging volume and an Rf coil for providing an Rf signal in the imaging volume. Preferably, the Rf coil also receives NMR signals from a specimen in the imaging volume.

Abstract: Apparatus and methods for performing MRI are disclosed wherein the encoding field has a multidimensional, preferably periodic, dependence. Two dimensional image information can be obtained without the necessity for switching the encoding field. Further, velocity information can be obtained. Preferred coil structures for providing preferred encoding fields are described.

Abstract: A magnet configuration particularly suited for MRI imaging in mammography is disclosed. The magnetic structure 50 has a rectangular shaped magnet with at least two parallel magnetic sources 5,6 connected by a ferromagnetic core flux path defining an air gap for imaging. A remote shimming C-shaped magnetic source is preferably used to decrease the front edge fringe effect of the magnetic structure 50 to create a relatively homogeneous field in the air gap beginning at the front edge for effective imaging.

Abstract: A motion and position sensor includes a stationary member having active conductors that carry energizing power and sensing conductors that are electromagnetically coupled by a movable member to generate signals in the sensing conductors that are representative of the position of the movable member. The movable member is contactless and therefore requires no electrical connection to any other component. Thus, frictional reactance torque and electromagnetically generated torque are reduced to a minimum.

Abstract: A suspension gyroscope has a stator and a rotor rotatably mounted with respect to the stator. The rotor has at least one generally hemispherical portion which is, at least in part, electrically conductive. The rotor may also have disc-like portions which project radially outwardly therefrom. Electrical coils serve to generate magnetic fields which induce eddy currents in the hemispherical portions and the disc-like portions. These coils serve to monitor the positions of the rotors with respect to three reference axes. A sensor for measuring departure of the rotor from a desired position is provided and may be optical or magnetic in nature.

Abstract: Received periodic pulses of varying amplitude, representing a measured analog signal, are alternately applied to two interpolation channels through gates alternately activated by a flip-flop element responsive to each incoming pulse. Each channel converts the applied pulses into an interpolated value which is summed with that of the other channel to substantially reproduce the original analog signal value. In a first specific arrangement, each pulse is converted, by the integration of the stored pulse amplitude, into a triangular shaped signal having a height equal to the corresponding pulse amplitude and a base equal to twice the pulse spacing. The successive triangular signals from each channel, each overlapping the adjacent pulse signals from the other channel, are summed to produce an interpolated analog output substantially equivalent to the original analog signal.