Abstract: An apparatus for measuring bio-magnetic fields includes a plurality of magnetometers for detecting magnetic fields generated from a live body; a driving circuit for driving the magnetometers; a computer for collecting output signals of the driving circuit in the form of data representing at least one waveform of the magnetic fields generated from the live body and for performing an arithmetic processing on the data representing the waveform of magnetic fields, a display unit, and at least one signal processing circuit for processing output signals of the driving circuit. The computer further performs an arithmetic processing of first-order differentiation on the waveform of the magnetic fields in a z direction with respect to time in order to create an arrow map and a contour map. The apparatus can also detect mechanical movement which occurs as blood flows in organs and organs move.

Abstract: A biomagnetic measurement apparatus having functions to detect the release of a magnetic field lock in a SQUID fluxmeter operation circuit due to the influence of a much greater noise level than that of a biomagnetic signal, to notify an operator of the release of the magnetic field lock, and to automatically or manually revert to a state for allowing magnetic measurement. The release of the magnetic field lock occurs when an integrator of the fluxmeter operation circuit is saturated. Thus, a high pass filter is provided at a subsequent stage of the integrator, and a function is provided to judge that the integrator is in a saturated state when the noise level of the output after passing through the high pass filter is lower than a pre-set threshold.

Abstract: A gradiometer integrating pickup coils comprises pickup coils 11Xp, 11Xn magnetically connected to a SQUID through associated input coils 2, and pickup coils 11Yp, 11Yn magnetically connected to a SQUID through associated input coils 2, respectively. Two superconducting loops are connected in series to each of the SQUIDs, when viewed from Josephson junctions 5. The input coils 2 form superconducting closed loops together with the pickup coils 11Xp, 11Xn, 11Yp, 11Yn associated therewith. The SQUIDs are respectively connected to form an 8-figured shape as a whole such that currents flow in two superconducting loops of each SQUID in opposite directions to each other, with respect to the application of a uniform field, in order to reduce environmental magnetic field noise.

Abstract: A biomagnetic field measuring apparatus including: a plurality of magnetometers each employing a superconducting quantum interference device for measuring the magnetic field generated from an organism; a unit for calculating a pseudo-current from a normal component of the magnetic field; a unit for calculating the pseudo-current from the magnetic field obtained from the plurality of magnetometers to integrate the pseudo-current in a fixed direction on the circumference at a fixed distance from each of the associated ones of the sensors; a unit for calculating a maximum value or a minimum value of the integral value obtained by the unit for performing the integral; and a unit for calculating a difference value between the absolute value of the maximum value and the absolute value of the minimum value.

Abstract: Improved calibrations associated with superconducting quantum interference devices (SQUIDs) are accomplished using a single calibration ring that is placed on an outer dewar wall. During initial calibration, a standard current is passed through the calibration ring and channel responses are measured and recorded. During re-calibration, any channel responses that have changed from the original value U to a new value U′, are identified and the corresponding empirical coefficients for these channels are changed from an old value of C to a new value C′ given by: C′=(U′/U)C Channel responses in subsequent measurements are divided by these coefficients C′ in order to make them equal for equal magnetic field inputs, or to provide equal channel sensitivities.

Abstract: A superconducting quantum-bit device based on Josephson junction has a charge as a first principal degree of freedom assigned to writing and a phase as a second principal degree of freedom assigned to reading. The device comprises a Cooper-pair box comprising first and second Josephson junctions defining a charge island of the Cooper-pair box closing up onto a superconducting loop. A read circuit comprises a read Josephson junction JL inserted into the superconducting loop and having a Josephson energy Ej at least 50 times greater than the Josephson energy of each of the first and second Josephson junctions.

Abstract: A bounding box or volume of interest is flooded with a modulated AC electromagnetic signal from a source. Different types of modulated signals may be used, including single-tone AM and FM. One or more sensors disposed on an object or body within the volume are then used to detect the signal, and a digital and/or analog spectral and phase analysis is performed on the received signal in hardware or software. The processing distinguishes between the direct source to sensor response and the response due to eddy currents. By removing the response due to the distorters, the effects of the electromagnetic distortion can be removed through a more conventional “free-space” solution. The invention finds applicability in a wide variety of environments, including head tracking systems and helmet-mounted displays for fighter aircraft; head trackers for armored vehicles; medical-guided surgery and biopsy; remote sensing, among other potential uses.

Abstract: The present invention is directed to satisfying the need to measure and monitor uterine activity non-invasively and accurately. Using superconducting quantum interference device sensors, we have established the feasibility of recording uterine contractile activity with high enough spatial-temporal resolution to determine the regions of localized activation and propagation over the uterus. With the large surface area and the shape of the array, spatial-temporal recordings of uterine activity were obtained using 151 sensors yielding a better insight into the mechanism of uterine contraction. By obtaining a contour plot of the magnetic field distribution, we were able to localize the areas of activation over the uterus during a contraction.

Abstract: An apparatus and method for the repeatable detection and recording of low-threshold molecular electromagnetic signals. The sample material and detection apparatus are contained with a magnetically shielded faraday cage to shield them from extraneous electromagnetic signals. The detection apparatus includes a detection coil and Super Conducting Quantum Interference Device (“SQUID”). White noise is injected external to the SQUID and the signals emitted by the sample material enhanced by stochastic resonance.

Abstract: In the present invention, when measuring magnetism of a measuring portion of a patient by making use of a dewar incorporating magnetism sensors each including a super conducting quantum interference device, a bed is at first positioned outside a position immediately below the dewar. At this position outside the position immediately below the dewar the patient is laid on the bed in an inspection posture. Marks are attached on the body of the patient at three points for setting X and Y axis coordinate on the measurement portion, at the position outside the position immediately below the dewar cross shaped beam patterns are projected and the position of the bed is adjusted so that the marks at the three points locate on the cross shaped beam patterns, thereafter, bed is transferred by a constant amount to the position immediately below the dewar.

Abstract: The present invention, in the physiological magnetic field measuring instrument, recognizes characteristic waveforms (for example, heart beats) repeatedly appearing by physiological activity from measured signal waveforms, registers one of measured heart beats as a reference waveform, evaluates the difference degree of each measured heart beat data from the reference waveform, and executes the averaging process using only waveforms whose difference degrees are less than the allowable value. The present invention registers waveforms whose difference degrees are more than the allowable value as abnormal data and puts them into the display enabled state. Discrimination information is as signed to measurement conditions necessary for measuring the physiological magnetic field and data analysis conditions and when the discrimination information is designated for measurement, the measurement conditions and analysis conditions can be read.

Abstract: Improved calibrations associated with superconducting quantum interference devices (SQUIDs) are accomplished using a single calibration ring that is placed on an outer dewar wall. During initial calibration, a standard current is passed through the calibration ring and channel responses are measured and recorded.

Abstract: According to this invention, a magnetic sensor (1) for measuring a magnetic field distribution of a measurement target S by using a SQUID (2) is characterized by including a storing portion (10) with an interior held in a vacuum state to store the SQUID (2), and a substantially needle-like flux introducing member (30) made of a high-permeability material to guide a magnetic flux from the measurement target (S) to the SQUID (2), wherein the flux introducing member (30) has one end (30a) located in the storing portion (10) to be away from the SQUID (2) and the other end (30b) located outside the storing portion (10).

Abstract: High balance, in the range of about 4×10−4 to about 10−3, is achieved in a gradiometer using Pyrex as the gradiometer support material. A superior technique is disclosed for winding superconducting wire loops with equal loop areas wherein cyanoacrylate glue is used to reduce slack in the wire in the process of winding. Furthermore, a minimal number of turns for each gradiometer type are used to maintain gradiometer sensitivity and to maintain high degree of mechanical balance. Additionally, low sensitivity SQUID magnetometers with optimally selected loop areas are placed among gradiometer channels in the directions of x, y, and z to measure magnetic fields. These measured fields are then fed into the gradiometer with coefficients roughly equal to (−1) (inversion) to compensate for the imbalances in the x, y, and z direction.

Abstract: A signal detector has a SQUID, a bias current supply circuit for supplying a bias current to the SQUID, and a drive circuit for detecting a magnetic flux by receiving a voltage signal of the SQUID and reading out the input signal as an output voltage. The drive circuit has two systems including a flux-locked loop system for converting a voltage signal of the SQUID into a current signal and making a magnetic flux inside the SQUID constant by feeding back a signal whereto, and an output system separate from and operating independently of the flux-locked loop system for converting a voltage signal of the SQUID and reading out the converted voltage signal without feeding back a signal to the SQUID.

Abstract: An apparatus for measuring electromagnetic characteristics includes a sample rod with a sample fixed to a lower part thereof, a helium 3 refrigerator, in which the sample rod is inserted, having a main pipe that forms around the sample rod a space that is cooled by helium 3, a device for supplying helium 3 to the helium 3 refrigerator, an inner tube portion, into which the main pipe is inserted, that supports at an upper part thereof the refrigerator, an outer tube that cools an outer periphery of the inner tube with helium, a liquid helium container that supplies liquid helium to the outer tube, and a device for measuring the electromagnetic characteristics of the sample.

Abstract: In order to measure magnetic characteristics of a sample, the latter is positioned above the SQUID so that both the SQUID and the sample are supported in a vessel in a gaseous nitrogen space above a liquid nitrogen coolant so that the measurement can take place at ambient pressure and in a nitrogen atmosphere.

Abstract: A solid-state quantum computing structure includes a set of islands that Josephson junctions separate from a first superconducting bank. A d-wave superconductor is on one side of the Josephson junctions (either the islands' side or the bank's side), and an s-wave superconductor forms the other side of the Josephson junctions. The d-wave superconductor causes the ground state for the supercurrent at each junction to be doubly degenerate, with two supercurrent ground states having distinct magnetic moments. These quantum states of the supercurrents at the junctions create qubits for quantum computing. The quantum states can be uniformly initialized from the bank, and the crystal orientations of the islands relative to the bank influence the initial quantum state and tunneling probabilities between the ground states.

Abstract: A solid-state quantum computing structure includes a d-wave superconductor in sets of islands that clean Josephson junctions separate from a first superconducting bank. The d-wave superconductor causes the ground state for the supercurrent at each junction to be doubly degenerate, with two supercurrent ground states having distinct magnetic moments. These quantum states of the supercurrents at the junctions create qubits for quantum computing. The quantum states can be uniformly initialized from the bank, and the crystal orientations of the islands relative to the bank influence the initial quantum state and tunneling probabilities between the ground states. A second bank, which a Josephson junction separates from the first bank, can be coupled to the islands through single electron transistors for selectably initializing one or more of the supercurrents in a different quantum state. Single electron transistors can also be used between the islands to control entanglements while the quantum states evolve.

Abstract: A minimal magnetic-field measurement Dewar vessel includes an inner container which contains a superconducting device and cooling medium, a radiation shield which is composed of an electrical insulation substrate and a first and second plurality of thin line stripes provided on opposite surfaces of the electrical insulation substrate so that the first plurality of thin line stripes is electrically insulated from the second plurality of thin line stripes and provided in a high stripe dense state, an outer container, and a cooling apparatus. A width of one portion of at least one of the first and second plurality of thin line stripes arranged in one area of the radiation shield surrounding the superconducting device is smaller than a width of another portion of the at least one of the first and second plurality of thin line stripes arranged in another area of the radiation shield, respectively.

Abstract: Method for detecting changes of magnetic response with at least one magnetic particle (20) provided with an external layer (22) in a carrier fluid. The method comprises utilization of a method of measurement comprising measuring of the characteristic rotation period of said magnetic particle regarding the effect of said external layer.

Abstract: In a superconductive quantum interference element comprising Josephson joints, a washer coil and a detecting coil constituting a superconductive loop and a feedback modulation coil, to provide a superconductive quantum interference element capable of promoting spatial resolution by preventing an effective detection area of the detecting coil from enlarging even when a width of a superconductive wiring constituting the detecting coil and a superconductive film at a vicinity of the detecting coil are larger than an inner diameter of the detecting coil, there is constructed a superconductive quantum interference element having a structure provided with a slit at a detecting coil and/or a superconductive film at a periphery of the detecting coil.

Abstract: A biomagnetic field measuring apparatus has a plurality of fluxmeters disposed externally of a living body and each including a superconducting quantum interference device (SQUID) for detecting a biomagnetic field generated from the living body, the plurality of fluxmeters being operative to detect a temporal change of a component of the biomagnetic field in a first direction which is vertical to the surface of the living body, an operation processor for performing computation for determining a temporal change of a value proportional to a root of square sum of differential value of the first-direction magnetic field component in second and third directions which cross the first direction and computation for integrating the temporal change of the value over a predetermined interval to determine an integral value, and a display for displaying the determined integral value. Distribution of magnetic fields generated from the heart is determined with a small number of fluxmeters.

Abstract: A method and apparatus is described for making multichannel signal measurements of weak signals in noisy environments, wherein the elimination of background interference signals from the multichannel signal measurement is performed. The method is based on an adaptive compensation technique in which the large interfering background signals are first recorded. By a statistical analysis of this multichannel measurement, independent components of the interference are determined. The apparatus is provided with compensator elements which are coupled to individual sensors for both collection and distribution of information on the interference signals during the measurement. In this way the output of a device can be made immune to the large amplitude interference components present in the device's environment. This reduces the dynamic range requirement for the data transport and storage systems.

Abstract: Improved superconducting coils for a nuclear magnetic resonance probe use capacitive elements that are located in regions further from an active sample volume than magnetic field generating elements to which they are electrically connected. The sample volume is a substantially oblong shape, and the magnetic field generating elements run substantially parallel to the major axis of the shape, while the capacitor elements run perpendicular to the major axis. The magnetic field generating elements and the capacitor elements may vary in length relative to their distance from a center of the oblong shape. The total number of capacitors formed by the loops may vary from one embodiment to another, typically depending on the necessary resonant frequency. A coil may use sub-coils, each of which incorporates a plurality of the magnetic field generating elements and interdigital capacitor elements, the capacitor elements preferably being located to both sides of the oblong shape.

Abstract: A self-adjusting assembly and method are disclosed. In the disclosed embodiments, a support assembly for supporting a device comprises a pair of support members for supporting the device. One of the members is adapted to help support the device from a ground, and another of the members is adapted to provide lateral support for the device and to permit free longitudinal movement of the device as it expands or contracts due to temperature variations.

Abstract: A magnetic field measuring apparatus has a magnetic field shielding apparatus including non-magnetic cylindrical members on which high-permeability sheets are located in a state of being partially overlapped with each other. The cylindrical members are located to surround an axis of a first direction concentrically and having a hollow portion, the cylindrical member located on an innermost-side having a first opening at one end of the first direction, a second opening at the other end of the first direction, and a third opening penetrating the cylindrical members in a direction perpendicular to the axis of the first direction. In addition, the magnetic field measuring apparatus has a living-body holder located in an inner-side space of the cylindrical member and a cryostat inserted into the third opening and maintaining SQUID magnetic-flux meters.

Abstract: A system, method, and computer program product are provided for scanning objects such as computer chips. A near-field scanning Single Electron Transistor (SET) is used to detect features of the object. In particular, the SET detects variations in an electric field surrounding or emanating from the object. The variation in the field may be associated with an irregularity in the object, such as an open in the circuitry of a chip. In the case of a chip or a multi-chip module, a voltage is applied to the line containing the suspected open. If an actual open is present, the open will be manifested in an irregularity in the electric field associated with the line. The SET detects the irregularity in the field. For the SET to operate, a sufficiently cold operating temperature is maintained for the SET. A very low (cryogenic) temperature allows the use of a larger, more sensitive SET. Scanning SETs are known in the literature, but in such systems the object to be scanned must also be at cryogenic temperatures.

Abstract: A method and system for determining the dominant cerebral hemisphere of a subject. There is further provided a method and system for using information obtained regarding hemisphere dominance for programming electronic devices such as robots, prostheses, as well as methods for using such information during treatment and surgical procedures in order to obtain superior function and/or movement when there is injury or disease to an area of the brain. A vectorial view of the role of callosum in the underpinning lateralities of speech and handedness, and as such, provides a technical definition of handedness (i.e., which hemisphere of the cerebrum is dominant in a particular individual subject). This technical definition is then used to completely accurately replicate or predict voluntary movements of the subject and this information, in turn, can be utilized in the field of prosthetics and robotics in order to obtain more accurate depiction of brain function and hence, more authentic replication of movement.

Abstract: A dewar for SQUID is provided. In the dewar for SQUID, an amount of leak gas discharged from absorbent arranged in the upper portion higher than the liquid surface level of liquid helium is small even if the liquid surface level of the liquid helium is lowered.

Abstract: An apparatus can detect a magnetic field with a high sensitivity using an ordinary-temperature pickup coil even when the pickup coil is arranged outside a cryostat. Specifically, the apparatus for measuring a magnetic field includes a pickup coil for detecting an external magnetic field, a SQUID electrically or magnetically connected to the pickup coil, a cryostat for holding the SQUID at low temperatures, and a driving device for driving the SQUID. The pickup coil is made of a normal-conducting material and is placed at an ordinary temperature outside the cryostat. By arranging outside the cryostat, the pickup coil can be brought close to a subject and can thereby detect a weak magnetic field in the subject with a high sensitivity.

Abstract: A SQUID bias current adjustment device supplies a sinusoidal current at 40 kHz, for example, to a coil to generate magnetic field at a SQUID. The amplitude of the field corresponds to a half period of a field-voltage characteristic. Voltage generated from the SQUID at this time is filtered by using a filter to pick out components of 40 kHz and 80 kHz. The picked out signal components are rectified and converted to direct current, and the bias current is adjusted such that the maximum value is obtained. In this way, a SQUID bias current adjustment device can be provided capable of automatically adjusting bias current properly in a short period of time.

Abstract: A biomagnetic field measuring apparatus including: a plurality of magnetometers each employing a superconducting quantum interference device for measuring the magnetic field generated from an organism; a unit for calculating a pseudo-current from a normal component of the magnetic field; a unit for calculating the pseudo-current from the magnetic field obtained from the plurality of magnetometers to integrate the pseudo-current in a fixed direction on the circumference at a fixed distance from each of the associated ones of the sensors; a unit for calculating a maximum value or a minimum value of the integral value obtained by the unit for performing the integral; and a unit for calculating a difference value between the absolute value of the maximum value and the absolute value of the minimum value.

Abstract: According to this invention, a magnetic sensor (1) for measuring a magnetic field distribution of a measurement target S by using a SQUID (2) is characterized by including a storing portion (10) with an interior held in a vacuum state to store the SQUID (2), and a substantially needle-like flux introducing member (30) made of a high-permeability material to guide a magnetic flux from the measurement target (S) to the SQUID (2), wherein the flux introducing member (30) has one end (30a) located in the storing portion (10) to be away from the SQUID (2) and the other end (30b) located outside the storing portion (10).

Abstract: A device for discharging fastening elements, and a method of preventing a device from discharging fastening devices into human flesh, are disclosed. The device includes a coil proximate a location of discharge, a capacitive element coupled in parallel with the conductive coil to form a resonant tank circuit, an oscillator that drives the tank circuit, a frequency detector, an amplitude control circuit and a processor. The detector detects a frequency of oscillation of the tank circuit as affected by a material proximate the coil. In response to an electrical signal from the oscillator, the control circuit generates a control signal that is provided back to the oscillator. Based upon the frequency and an additional signal functionally related to the control signal, the processor provides an output signal that prevents the device from discharging when the material proximate the coil is human flesh.

Abstract: According to this invention, a magnetic sensor (1) for measuring a magnetic field distribution of an object (40) by using a SQUID (7), includes an inner container (3) forming a substantially cup-like shape to store therein a coolant (8) for cooling the SQUID, an outer container (2) which stores the inner container and has a window (23) at a position opposing a bottom of the inner container (3), and a heat conductor (6) located such that one side thereof is attached to a heat conductor attaching portion (3b) of the bottom of the inner container and the other side thereof opposes the window of the outer container, the other side being attached with the SQUID, wherein a space (4) between the inner container (3) and the outer container (2) is held in substantial vacuum, the inner container (3) is made of a metal material, and the outer container (2) is made of a nonmetallic material.

Abstract: A magnetic field measuring apparatus for precise cancellation of environmental noise includes a plurality of first SQUID gradiometers to detect noise and biomagnetic fields, a plurality of second SQUID gradiometers to detect noise, a driving circuit to drive these gradiometers, and a computer to execute signal processing after collecting the signals detected by these gradiometers. First and second SQUID gradiometers are provided which include first-order gradient pickup coils with the baselines formed by the coils of second gradiometers being shorter than those of first gradiometers. The apparatus cancels noise, from detected biomagnetic signal waveforms, caused by variant noise cancellation rates of the coils of first gradiometers, different baselines of the coils of second gradiometers, and the frequency property of a magnetically shielded room in which the apparatus is installed.

Abstract: A scanning head for eddy-current testing includes a probe coil configuration disposed on a film on a film base. The film base is matched to a shape of an object to be tested. This allows quick, low-interference eddy-current testing. A method for producing a scanning head for an eddy-current test and an eddy-current test method are also provided.

Abstract: A flux locked loop for providing an electrical feedback signal, the flux locked loop employing radio-frequency components and technology to extend the flux modulation frequency and tracking loop bandwidth. The flux locked loop of the present invention has particularly useful application in read-out electronics for DC SQUID magnetic measurement systems, in which case the electrical signal output by the flux locked loop represents an unknown magnetic flux applied to the DC SQUID.

Abstract: The present invention provides an improved magnetometer to efficiently evaluate subsurface characteristics of conductive material without destroying the material. A white noise generator drives an induction coil to induce measurable currents in a work piece at multiple frequencies. Multiple super conducting quantum interference devices (SQUIDs) measure the magnetic filed created by the currents. The SQUIDs are housed in a liquid nitrogen Dewar. The SQUIDs are aligned along a Josephson junction and are manufactured on a single substrate. A mover moves the work piece adjacent the super conducting quantum interference devices. A computer analyzes the measured data.

Abstract: In a superconductive quantum interference element comprising Josephson joints, a washer coil and a detecting coil constituting a superconductive loop and a feedback modulation coil, to provide a superconductive quantum interference element capable of promoting spatial resolution by preventing an effective detection area of the detecting coil from enlarging even when a width of a superconductive wiring constituting the detecting coil and a superconductive film at a vicinity of the detecting coil are larger than an inner diameter of the detecting coil, there is constructed a superconductive quantum interference element having a structure provided with a slit at a detecting coil and or a superconductive film at a periphery of the detecting coil.

Abstract: Read-out electronics for DC SQUID sensor systems, the read-out electronics incorporating low Johnson noise radio-frequency flux-locked loop circuitry and digital signal processing algorithms in order to improve upon the prior art by a factor of at least ten, thereby alleviating problems caused by magnetic interference when operating DC SQUID sensor systems in magnetically unshielded environments.

Abstract: A modulation current at a predetermined frequency f is applied from an AC source to a flux locked loop for maintaining magnetic flux supplied to a SQUID at a constant value. An output voltage is picked out from the SQUID in this state to which a predetermined bias current is being applied from a current and field bias application circuit, and the picked out voltage passed through a filter and a rectifier is monitored by a voltage monitor. The filter picks out a frequency component of 80 kHz which is twice as high as the frequency component f, 40 kHz, applied from the AC source, and maximizes it. In this way, a method and a device for easily adjusting magnetic field bias in a modulation drive circuit for a SQUID can be provided.

Abstract: A magnetic field measuring apparatus has a magnetic field shielding apparatus including non-magnetic cylindrical members on which high-permeability sheets are located in a state of being partially overlapped with each other. The cylindrical members are located to surround an axis of a first direction concentrically and having a hollow portion, the cylindrical member located on an innermost-side having a first opening at one end of the first direction, a second opening at the other end of the first direction, and a third opening penetrating the cylindrical members in a direction perpendicular to the axis of the first direction. In addition, the magnetic field measuring apparatus has a living-body holder located in an inner-side space of the cylindrical member and a cryostat inserted into the third opening and maintaining SQUID magnetic-flux meters.

Abstract: A technique for accurately determining states of bioelectric currents occurring in particular positions in a site of interest of a patient. Transfer functions between the particular positions and each magnetic sensor are derived from a positional relationship between the site of interest and each magnetic sensor. Weight coefficients are computed from an inverse matrix obtained by adding a predetermined value to a matrix of the transfer functions, and virtual biomagnetism information obtained virtually by bioelectric currents set to the particular positions. Enhanced biomagnetism information with only the biomagnetism from the particular positions enhanced is acquired by superposing the weight coefficients of measured biomagnetism information. Based on this enhanced biomagnetism information, states of bioelectric currents occurring in the particular positions are determined accurately.

Abstract: A method of performing synthetic aperture magnetometery on the signals from a target organ using an array of biomagnetic sensors positioned in a predetermined manner around the target organ, each sensor in the array having a position vector and an orientation vector relative to a common coordinate system encompassing the target organ.

Abstract: A magnetic field sensor which can be used as an active antenna is disclosed that is capable of small size, ultrawideband operation, and high efficiency. The sensor includes a multiplicity of magnetic field transducers, e.g., superconducting quantum interference devices (SQUIDs) or Mach-Zehnder modulators, that are electrically coupled in a serial array. Dummy SQUIDs may be used about the perimeter of the SQUID array, and electrically coupled to the active SQUIDs for eliminating edge effects that otherwise would occur because of the currents that flow within the SQUIDs. Either a magnetic flux transformer which collects the magnetic flux and distributes the flux to the transducers or a feedback assembly (bias circuit) or both may be used for increasing the sensitivity and linear dynamic range of the antenna.

Abstract: Architecture for frequency multiplexing multiple flux locked loops in a system comprising an array of DC SQUID sensors. The architecture involves dividing the traditional flux locked loop into multiple unshared components and a single shared component which, in operation, form a complete flux locked loop relative to each DC SQUID sensor. Each unshared flux locked loop component operates on a different flux modulation frequency. The architecture of the present invention allows a reduction from 2N to N+1 in the number of connections between the cryogenic DC SQUID sensors and their associated room temperature flux locked loops. Furthermore, the 1×N architecture of the present invention can be paralleled to form an M×N array architecture without increasing the required number of flux modulation frequencies.

Abstract: An minimal magnetic-field measurement Dewar vessel including an inner container which contains a superconducting device and cooling medium; a radiation shield which a plurality of thin line stripes is electrically insulated and in a high strip dense state; an outer container which surrounds the radiation, and in which a vacuum state is kept; and a cooling apparatus which cools the radiation shield; wherein the number density and the width of, each thin line stripe arranged surrounding the superconducting device is larger and smaller than those values of a thin line stripe arranged in other areas, respectively. Further, by the above composition, the thermal resistance of the radiation shield can be reduced, and this can reduce magnetic noises and the evaporation amount of liquid helium.

Abstract: A magnetic field measurement apparatus comprises a plurality of magnetometers each comprising SQUID's and three detection coils each of which detects each of three orthogonal directional magnetic field components ( Bx, By, Bz) of a magnetic field generated from a subject to be inspected, a display which displays time variation of waveform of magnitude {{square root}(Bx2+By2+Bz2)} of magnetic field synthesized by square sum of each of the three orthogonal directional magnetic field components of the magnetic field generated from the subject to be inspected, a holding means for holding Dewar's vessel for arranging magnetometers therein, and a controlling means for controlling a positional relationship between the subject to be inspected and the Dewar's vessel.