Abstract: An apparatus includes an enclosure having a wall defining an interior of the enclosure and having 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 and an electrical coil structure are positioned within the enclosure. The electrical coil structure is driven by a controllable electrical current source. A background-field-reducing feedback controller has a controller input responsive to a background-field magnetometer output signal, and a controller output in communication with the current source command signal input. A signal magnetometer, such as a biomagnetometer, within the enclosure detects a magnetic field produced by a source within the enclosure.

Abstract: An apparatus includes an enclosure having a wall defining an interior of the enclosure and having 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 and an electrical coil structure are positioned within the enclosure. The electrical coil structure is driven by a controllable electrical current source. A background-field-reducing feedback controller has a controller input responsive to a background-field magnetometer output signal, and a controller output in communication with the current source command signal input. A signal magnetometer, such as a biomagnetometer, within the enclosure detects a magnetic field produced by a source within the enclosure.

Abstract: A magnetometer comprises a magnetic field pickup coil and a magnetic field detector that receives electrical signals from the pickup coil and produces an electrical detector output responsive thereto. The pickup coil and detector, which are preferably made of high temperature superconductors, are enclosed in an insulated enclosure having no vacuum insulation structure. Preferably, the enclosure is made of a foamed polymer material such as styrofoam. A coolant is provided to the interior of the enclosure, to cool the pickup coil and detector to a temperature below their superconducting transition temperature. A number of such modular magnetometers may be connected together to form an array.

Abstract: A biomagnetometer includes a magnetic field sensor including a magnetic field pickup coil and a detector of small electrical currents flowing within the pickup coil. A vacuum-tight enclosure surrounds the sensor. The enclosure has a concavely upwardly curved first wall, with the magnetic field pickup coil located adjacent to the first wall. A vented reservoir of liquefied gas is located within the enclosure, and a solid thermal conductor extends from the sensor. There is a vacuum-tight thermal feedthrough by which the solid thermal conductor passes between the interior and the exterior of the enclosure. Electronic circuitry for filtering and amplifying the signals of the detector is also provided. Such a biomagnetometer is placed below the body of a reclining subject, and a second portion of the biomagnetometer can be placed above the body.

Abstract: A biomagnetometer includes a magnetic field sensor unit having a magnetic field pickup coil. A vessel contains the sensor unit. The vessel includes a flexible contact face with the magnetic field sensor unit mounted in the interior of the vessel adjacent to the flexible contact face. Insulation at the flexible contact face of the vessel prevents excessive heat flow through the flexible contact face. Pickup units using this structure can be connected together into flexible or rigid arrays. In operation, the pickup coil is cooled to a temperature of less than its superconducting transition temperature. A detector measures the magnitude of magnetic fields sensed by the sensor unit.

Abstract: A biomagnetometer measures a magnetic field produced by a source within the body of a subject, using a magnetic field sensor system. The biomagnetometer includes an ultrasonic transceiver that determines the internal physical structure of the body with ultrasonic waves. An electromagnetic transmitter/receiver establishes the position of the ultrasonic transceiver relative to the magnetic field sensor system. A computer controls and integrates the magnetic field sensor system, the ultrasonic transceiver, and the electromagnetic transmitter/receiver. The biomagnetometer permits a direct association between the measured biomagnetic field and the location of the source within the body of the subject.

Abstract: An apparatus for making magnetic measurements of the human body includes a biomagnetometer having a magnetic field sensing coil that measures magnetic fields arising from a selected portion of a body. A position monitor used in conjunction with the biomagnetometer produces no magnetic fields that can interfere with the taking of magnetic field measurements, and can operate simultaneously with the taking of magnetic field measurements. The position monitor includes an optical target mounted on the selected portion of the body, the optical target having a variation in light reflectance across the target. An input optical guide directs a beam of light at the target, an output optical guide collects a reflected beam of light from the target, and a limit detector receives the beam of light from the output optical guide and determines whether the intensity of the received light varies outside of predetermined limits.

Abstract: An apparatus for making bioelectromagnetic measurements of the human body includes an apparatus for measuring the bioelectromagnetic reaction of a living body to a tactile stimulation and a tactile stimulator that controllably applies a tactile stimulation to the body without creating a magnetic or electrical field that is detected directly by the apparatus for measuring the bioelectromagnetic reaction. The tactile stimulator includes a pressure chamber closed on one side by a movable body such as a piston or flexible membrane, a conduit that transmits pneumatic pressure to the pressure chamber, and apparatus for applying pneumatic pressure to the conduit. The measuring apparatus, such as a biomagnetometer, may be located within a shielded room, and in this case the pressure chamber and movable body are preferably located within the shielded room, the apparatus for applying pneumatic pressure is located outside the room, and the conduit passes from the exterior to the interior of the room.

Abstract: An information storage device includes a magnetic recording medium, preferably supported upon a rotating disk, an electromagnetic writing device that writes magnetic patterns into the recording medium, and a superconducting quantum interference device (SQUID) that reads the magnetic patterns in the recording medium, the writing device and the SQUID preferably being mounted upon a read/write head. The SQUID as operated in its superconducting state is a highly sensitive and directional detector of the magnetic state of the recording medium, permitting it to be spaced relatively distantly from the recording medium yet read the state of small areas of the medium. Use of high temperature superconductors in the SQUID permits practical construction of the information storage device. The read/write head may support a plurality of write devices, and an array of SQUIDs can be utilized so that little or no relative movement of the read/write head is required to read and write from all tracks of the disk.