Abstract: A pistol detection system including a main control unit for controlling all constituting units of the system, a magnetic force generating unit for generating a control signal for a generation of magnetic fluxes, a gate for generating magnetic fluxes of a desired intensity while receiving the generated magnetic fluxes, thereby generating an induced voltage, a magnetic force receiving unit for detecting the induced voltage, thereby determining whether or not a person who passes through the gate carries a pistol, a camera for picking up an image of the person who passes through the gate while carrying a pistol, a time generating unit for outputting time information, an image signal processing unit for composing an image signal generated from the camera with the time information generated from the time generating unit, storing the resultant signal, an automatic dialing unit for automatically dialing a previously set telephone number, and interior and exterior alarm lamps respectively for generating an alarm and e

Abstract: A miniturized coil arrangement made by planar technology for the detection f material having a magnetic permeability other than zero, provided with a magnetizable core in a first plane of a substrate, an electrically energizable coil wound around a first section of a core to generate flux therein and at least one other coil in a second plane of the substrate adjacent another section of the coil responsive to disturbance in the flux.

Abstract: A process for characterization of magnetic materials for validating documents carrying marks which include magnetic materials is based on an analysis of signals supplied by an oscillator generating a low frequency signal supplying emitter windings and receiver windings that have different conformations. The receiver windings (A) and (B) are joined to an amplifier that has two outputs (S1) and (S2), output (S2) yielding, upon conformation, a signal (X) that is used as a time reference, and output (S1) yielding, after various transformations, two signals (Y) and (Z), each of which is entered into a microprocessor which, together with valid magnetic marker data, generate signals accepting or rejecting the document.

Abstract: In a time domain electromagnetic mapping technique of the type using transmitter pulses of half-sinusoidal waveform, with the half sinusoids being segments of a sinusoidal waveform having a frequency and corresponding to a resonant frequency of the transmitter coil, an improved current fall time at the end of each pulse is obtained by forming each transmitter pulse of plural immediately successive half sinusoids, the transmitter coil being tuned to an appropriately increased resonant frequency relative to the pulse repetition rate. Circuits for generating the improved pulse waveforms are disclosed.

Abstract: A method of determining a concentration of magnetic powderly material in a sample is disclosed. In this method, a pair of series-connected exciting coils are disposed in such a manner that magnetic fields generated from the respective exciting coils oppose to each other. A detecting coil is disposed at a position where the magnetic fields from the pair of exciting coils cancel out each other. A sample mixed with magnetic powder is inserted into one of the pair of exciting coils. Then, the method detects a voltage induced in the detecting coil in association with the insertion of the sample into the exciting coil and determines the concentration of the magnetic powder in the sample based on the detected voltage.

Abstract: A method of increasing the spatial resolution of polar coordinates sensor devices by phase-amplitude modulating the sine-cosine excitation signals to the hollow toroid driving core. A rotating elliptical sensing pattern is generated by digital synthesis means. Values of the elliptical sensing pattern and its complete revolution are stored in digital "look-up" tables and sequentially read at a high rate into two digital-to-analog converters to produce two "staircase" approximations of the sine-cosine waveforms. The ellipse generation has a first angular frequency and the ellipse precession has a second sub-multiple frequency.

Abstract: An improved two-coil apparatus for measuring the absolute value of magnetic penetration depth .lambda. of superconductor films which is capable of measuring the absolute value of magnetic penetration depth which is denoted as .lambda. of a large area high temperature superconductor film using a low frequency or a static weak magnetic field, which includes a drive coil that is designed to suppresses the screening current of the film at the film edge a receive coil opposingly spaced-apart from the drive coil; sample holders disposed at the left-and right-sides of the receive coil; a large area low temperature superconductor film attached on the sample holder between the drive coil and the receive coil; and a large area high temperature superconductor film mounted on the large area low temperature superconductor film between the drive coil and the receive coil.

Abstract: A method for excitation and detection of magnetic resonance elements (10) in an interrogation zone (11), whereby a magnetic excitation signal is generated by at least one excitation means (12) and is supplied to the resonance element, so as to force the resonance element (10) into mechanical self-oscillation, and whereby a magnetical signal caused by the self-oscillation is detected. The excitation signal is generated by at least two excitation means (12) being located at a distance from each other, whereby a symmetry plane (14) for the excitation signal is obtained between the excitation means (12). The magnetic signal caused by the self-oscillation is symmetrically recorded at both sides of the symmetry plane (14), and the resonance elements are placed between an excitation means (12) and the symmetry plane (14), the recorded signal thereby containing the magnetic signal caused by the self-oscillation, but lacking the excitation signal.

Abstract: A plasma density monitor is described for determining the ion current of a plasma flowing through a conduit (14). The monitor comprises a plate (18) having a face and an orifice extending from the face through the plate. The internal surface of the orifice conforms with the internal surface of the conduit when the face is adjacent the conduit. The monitor also comprises a detector circuit (22) for sensing the ion current collected by the internal surface of the plate (18). Another embodiment monitors plasma density by determining electrical conductivity in the afterglow of a microwave induced plasma. A resonant LC circuit (50, C3) has a multi-turn coil (C3) surrounding the conduit, an RF oscillator circuit (54, 56) for driving the LC circuit, and a circuit (64, 66, 68, 70, 72, 76) for measuring the decay time of the LC circuit. Plasma flowing through the conduit alters the resistivity of the coil and the time constant of the LC circuit proportional to the electrical conductivity of the flowing plasma.

Abstract: An elongated hollow toroid driving core having a pick-up core formed as an integral part. A cross shaped driving core having two orthogonal sine-cosine excited flux circuits, a polar sensor is mounted where the cross arms intersect, the axis of the polar sensor being perpendicular to the driving core surface, thus disposing the winding turns of the pick-up coil coplanar to the driving flux lines. A third embodiment of a driving core device includes a hollow toroid and cross shaped driving core combination providing dual interacting rotating fields generating a sensing pattern having additive or subtractive dipoles that may be steerable.

Abstract: The invention is an apparatus for controlling an electrical heating element to control a cooking temperature of a cooking pot and contents therein.

Abstract: A magnetic influence system for underwater systems has a low-inductance source coil for generating an impulsive magnetic dipole field in the vicinity of the underwater system. A high-voltage power source provides a transient voltage pulse to the source coil, resulting in a rapid current pulse rise time in the source coil. The impulse source coil is mounted on a non-conductive hull section of the underwater system. A plurality of impulse sensor coils are also distributed on the system hull at the null points of the magnetic dipole field and detect the returning scattered signal generated by the impulse source coil.

Abstract: In a proximity-detector, a Hall transducer produces a signal Vsig. Two counters, P-counter and N-counter count pulses from a clock and produce count signals respectively to two DACs, PDAC and NDAC. The DACs output signals track and hold, respectively, the positive pulses and negative pulses in Vsig. These output signals are compared with Vsig to produce a proximity-detector binary output voltage Vout that becomes high when a tracking voltage V.sub.DAC-P produced by PDAC rises to each peak positive voltage V.sub.pk in Vsig, and that becomes low when a tracking voltage V.sub.DAC-P falls to each peak negative voltage in Vsig. The peak V.sub.DAC-P is held until Vsig drops by a fixed amount below V.sub.pk to produce an output pulse that resets the counter connected to PDAC at a time shortly following the actual peak in Vsig. Similarly, the peak V.sub.DAC-N is held until Vsig rises a fixed amount above V.sub.DAC-N to produce an output pulse that resets the counter connected to NDAC. The N-counter is reset at t.sub.

Abstract: A metal detector system is described for detecting metal objects in a monitoring zone, where the metal detector system comprises: (a) a transmitter coil for generating a magnetic filed in the zone to be monitored, the coil being disposed on a first side of the zone; (b) a first sensing coil disposed on a second side of the zone opposed to the first side, the first sensing coil generating a first sensing signal in response to perturbations in the magnetic field caused by the presence of a metallic object in the zone; (c) a second sensing coil disposed on the second side of the zone, the second sensing coil being spaced apart from the first sensing coil, the second sensing coil generating a second sensing signal in response to perturbations in the magnetic field caused by the presence of a metallic object in the zone; and (d) a sensing circuit for comparing the amplitudes of the first and second sensing signals to generate a difference signal and for generating a first trigger signal for a zero down-crossing of

Abstract: A monitoring apparatus is provided for determining permeabilities of a vacuum-deposited second pole piece of a magnetic head at the wafer level by providing wafer-mounted monitors which have layers formed by the same masking and deposition steps employed in making the magnetic heads so that the layers of the monitors are replicated layers, except for a shaping layer on top of a replicated second pole piece of some of the monitors. Each monitor is a transformer wherein each of a primary winding and a secondary winding comprises essentially a replicated magnetic head. The first and second pole pieces of the replicated magnetic heads are joined so as to magnetically couple the primary and secondary windings that constitute the transformer.

Abstract: Metal detector (1) including an oscillator (10) generates an RF field in the vicinity of the head (2). Two reference signals (13, 14) are generated, one signal (14) being in phase with the oscillator (10) and the other signal (13) being shifted from the oscillator signal by 90.degree.. The signal (8,9) from the receive coils (6,7) is amplified and quadrature demodulated into two signal channels, each channel giving the orthogonal component of the original signal (8,9). The signals of each channel are digitized and read by a microprocessor (37) that controls the amplitude of the balance signals (43, 49). One signal (43) is in phase with the oscillator signal (11) and the second signal (49) is shifted 90.degree. from the oscillator signal (11). Signals (43,49) return to detection circuitry (6,7), maintaining balance on each channel. By monitoring the magnitude of the phase shifted and unshifted signals (49,43), the microprocessor (37) determines the characteristics of the product.

Abstract: A metal detection device is disclosed and includes a housing defining a central aperture. An induction member is mounted to the housing and surrounds the aperture for generating an output voltage in response to the presence of a metal object near the induction member. A mechanism is provided for calibrating the induction member by comparing the output voltage to a reference voltage to establish a threshold voltage which is unaffected by transient fluctuations in the output voltage. A mechanism is also provided in the housing and spaced about the aperture for selectively sensing an object passing through the aperture. The sensing mechanism generates a detection signal in response to passage of an object through the aperture only upon activation of the sensing mechanism. A mechanism activates the sensing mechanism upon generation of an inductive member output voltage above the threshold voltage. Finally, a device is provided for triggering an alarm in response to the generation of the detection signal.

Abstract: A device for the measurement by induction of a medium through a metal wall using a transmission portion permitting the induction of a signal in the medium beyond the metal wall and a receiver for receiving a signal transmitted by the medium in response to the induced signal. The transmission portion includes at least one current generator directly connected to the metal wall in such a way that the current passing into the wall induces a signal beyond the wall.

Abstract: A system for detecting metal targets located in a background environment such as the ground evaluates metal targets by processing components of signals at two or more different frequencies. A component of the received signal induced by the ground can be eliminated by subtracting signal components measured at two different frequencies. The received signal can be processed to account for changes in the background response with frequency. The type of an unknown target can be identified by processing background excluded components to produce data characterizing the target type.

Abstract: A device for and method of testing toroidal magnetic cores for magnetic anomalies which prevent uniform performance of the cores. The core is positioned on a drive device which can rotate the core through 360.degree.. The core passes through an input winding which receives the test signal and an output winding coupled to a display device which shows the presence or absence of such magnetic anomalies.

Abstract: Apparatus and methods are disclosed which provide increased sensitivity, selectivity and dynamic range for non-contact measurement of actual physical and/or kinematic properties of conducting and magnetic materials. The apparatus and methods are based upon various methods for increasing sensitivity, selectivity and dynamic range through proper construction of a magnetometer sensor and for proper selection of operating point parameters for the application.A measurement apparatus for measuring one or more MUT properties includes an electromagnetic winding structure which, when driven by an electric signal, imposes a magnetic field in the MUT and senses an electromagnetic response. An analyzer is provided for applying the electric signal to the winding structure. A property estimator is coupled to the winding structure and translates sensed electromagnetic responses into estimates of one or more preselected properties of the material.

Abstract: A steel hardness measurement system and method of using same are provided for measuring at least one mechanical or magnetic characteristic of a ferromagnetic sample as a function of at least one magnetic characteristic of the sample. A magnetic field generator subjects the sample to a variable external magnetic field. The magnetic field intensity of the magnetic field generated by the magnetic field generating means is measured and a signal sensor is provided for measuring Barkhausen signals from the sample when the sample is subjected to the external magnetic field. A signal processing unit calculates a jump sum rate first moment as a function of the Barkhausen signals measured by the signal sensor and the magnetic field intensity, and for determining the at least one mechanical or magnetic characteristic as a function of the jump sum rate first moment.

Abstract: A security thread for use in a paper-based value document, such as currency or banknote paper, includes a plastic substrate coated with one or more regions of "soft" magnetic material. A device for verifying both the authenticity and the denomination of the document includes a coil that is driven by an alternating current to thereby provide a uniform magnetic field within a predetermined spatial region. As the document passes in proximity to the drive coil, the applied magnetic field saturates the regions of magnetic material on the security thread. The magnetic regions provide a response magnetic field that, because of the saturation of the magnetic regions, is a non-linear response containing a multiple of frequency components, including a component at the fundamental or drive frequency and various harmonic frequency components. A receive coil senses the response magnetic field.

Abstract: A microdevice is provided for measuring the electromagnetic characteristics of a medium in a borehole. The microdevice includes at least one emitting or transmitting coil (31), and at least one receiving coil (41,51). The microdevice generates an A.C. voltage at the terminals of the transmitting coil and measures a signal at the terminals of the receiving coil. The microdevice also includes an E-shaped electrically insulating, soft magnetic material circuit serving as a support for each of the coils and which is positioned adjacent to the medium in the borehole.

Abstract: A structure for a small and durable eddy-current probe for testing of conductive tubes, pipes and apertures in work pieces such as vias in printed circuit boards. A thin, rectangular elastic dielectric printed circuit substrate has sensor conductor loops printed on one side. That dielectric printed circuit substrate is placed on a thin rectangular steel sheet (the probe body) and the substrate and body are rolled into a strong, unitary eddy current probe structure which has the sensor loops 3 safely protected on the interior of the rolled-up probe body 1. The steel probe body cylinder thus formed has an external diameter D and an internal diameter d. The ratio of D/d is, preferably, in a range of 1.4 to 1.6. Bonding pad sites 5 are formed on the elastic substrate, for making electrical connections to the probe. The probe interior may be filled with magnetically conductive material.

Abstract: This invention is for a pulse induction metal detector which uses combinations of the signal detected during non-transmission of the magnetic field to eliminate those contributions to the signal due to the remanent magnetization of ferrites and asynchronous magnetic fields within the target volume.

Abstract: A metal detector especially adapted to prevent the inadvertent or unauthorized deposit of metal objects into receptacles includes a housing provided with a central opening surrounded by a funnel-like surface for directing articles into a receptacle such as a medical waste disposal bag, a trash can, or a laundry hamper. For use in the medical field to prevent the inadvertent disposal of surgical instruments, the metal detector housing may be pivotally connected by a hinge mechanism to a medical waste bag disposal bag holding cart to allow convenient removal and replacement of disposal bags. Battery powered detection circuitry includes a detector coil surrounding the central opening and operative to trigger visual and audible alarms for signalling the passage of a metal article through the housing opening if the output voltage in the detector circuit exceeds a predetermined threshold value.

Abstract: A metal detector comprise a coiled conductor located within a metal enclosure operative to provide an a.c. generated primary electromagnetic field. Metal screening is provided adjacent the coil so as to provide a secondary induced magnetic field which opposes the primary electromagnetic field so as to significantly reduce the metal free zone.

Abstract: An arrangement of the magnetic detection and excitation head has an excitation head with a U-shaped excitation core of soft magnetic material forming two legs, each having an end plane facing a surface of a measured object, and an excitation coil wound on the core excitable by a low frequency current; and a detection head with a rod-shaped detection core of non-magnetic or soft magnetic material and a detection coil wound thereon. An end plane of the detection core which is to be close to the surface of the object, and the end planes of the two legs of the excitation core are arranged such that the end plane of the detection core is between the end planes of the two legs and all the end planes are substantially on a common flat plane.

Abstract: High-energy permanent magnetic materials are characterized by exposing the material to sequential pulsed fields of respectively different rates of change of magnetic field strength, sensing the total magnetic field strength, sensing the total magnetic field generated in the sample by the respective pulses including eddy currents induced therein, and eliminating eddy current components from the said fields, whereby the net magnetic fields relate to the magnetic characteristics of the sample. Preferably the pulsed field is capacitor-generated via a solenoid and the rate of change of the magnetic field strength is produced by holding the waveform constant and altering the pulse duration, for example by providing taps on the solenoid together with an inductor and a balancing resistor, to enable the ratio of resistance to inductance to be maintained substantially constant across the range of taps utilized.

Abstract: A non-obtrusive, non-threatening weapon detection system for discriminating between a concealed weapon and other metal objects. The system is designed for a high probability of detection with a low false alarm rate. When the subject system is in use, a person under surveillance need not be aware that he or she is being monitored nor is the person's privacy invaded. The system includes the use of a magnetic field generator for transmitting low intensity electromagnetic step pulses causing eddy currents to flow in any metal object carried by the person. The eddy currents scatter a signal that is detected by one or more fast response magnetic field sensors. The eddy currents excited in the metal body, which may be called a target, by the leading edges of the transmitted step pulses take the form of an exponentially decaying transient immediately following the step pulses abrupt initial rise. This "decay curve" provides a basic observable, namely, a time constant of the current decay.

Abstract: Apparatus for measuring the sidewall thickness of cylindrical articles during in-process ram and die drawing, inclined axis multiple polar sensors induce eddy currents by means of the angular motion of a rotating magnetic field, the signal phase angle representing sidewall thickness, also ram and die centering signals generated. Inclined axis polar sensors also measure both cylindrical and flat article hardness by phase shift.

Abstract: A high frequency magnetic property measuring apparatus for soft magnetic film includes a magnetic detection device for detecting the intensity of magnetization in a sample material, a high frequency magnetic field generator for generating magnetic field, a power source for supplying current to the magnetic field generator, and a data processing device for getting high frequency magnetic parameters of the sample by using a detection signal output from the magnetic detector. The magnetic field generator is made up of a plane-shaped coil of a conductor having a configuration in which both ends of the plane-shaped coil are closed to form a cavity as a second internal cavity in which the detector is placed. The magnetic detector is made up of a plane-shaped coil of a conductor having a configuration in which both ends of said plane-shaped coil are closed to form a cavity as a first internal cavity in which the sample material is placed. The magnetic detector is placed in the magnetic field generator.

Abstract: A measuring circuit obtains desired characteristic values of a device under test by accurately measuring a voltage and a current. Errors are eliminated that originate from the transmission characteristics of cables used in measurements at high frequencies and measurements using long cables. The errors are eliminated by connecting resistors that are equal in resistance to the characteristic impedance of cables, to the inputs of the cables which connect the device under test to a measuring device.

Abstract: An active impulse magnetometer includes a magnetic field transmitter which generates a low frequency magnetic impulse waveform. A separate magnetometer receiver responds to the transmitted waveform, and produces a receive waveform which is transformed by a Fast Fourier Transform device into the frequency domain. The transformed signal is processed to indicate the presence of any detected objects.

Abstract: The present invention is a measuring method for detecting penetrant metal intruded in refractories having a conductive cover at a first wall and a nonconductive surface at a second wall and for measuring their thickness. At least one sensor head is used including a metal sensor with a first and second conductive coil for measuring distance between the sensor head and a conductive substance and a distance sensor for measuring distance between the sensor head and the refractories. The sensor head is disposed at a plurality of fixed positions close to the second wall to face the refractories and an alternating current is applied to the first coil to generate an eddy current in the conductive substance which faces the metal sensor. An induced voltage induced in the second coil by at least the eddy current is detected and a first distance is obtained between the sensor head and the conductive substance based on the detected induced voltage.

Abstract: An inductive proximity sensor determines if a metallic object is in close proximity. An inductor is placed near the object. Several switches control the direction of the voltage passing through the inductor. During a first time period, the voltage flows through the inductor to induce a magnetic field in the object. During the second time period, the voltage is reversed in the inductor to quickly eliminate any current in the inductor. The decaying magnetic field in the object induces a voltage in the inductor which is measured during a third time period and compared to a reference value to determine the proximity of the object to the sensor.

Abstract: A magnetic flux microscope that measures the magnetic field about a sample surface. The apparatus uses a thin-film superconducting quantum interference device (SQUID) as the scanning device. Magnetic shielding is provided about the SQUID and is held stationary relative to the SQUID. The apparatus and method provides a very high magnetic image of the sample with a very high spatial and field resolution.

Abstract: A magnetic inspection head adapted for use with samples having non-planar surfaces. A magnetically permeable core has a pair of poles joined by a magnetically permeable bridge to form a closed magnetic circuit between the pole legs, bridge and the test material. Each pole has magnetically permeable support means terminating in a magnetically permeable deformable surface for engaging the sample. The support means is yieldable such that when the inspection head is placed in contact with the irregular surface of the sample, the deformable surface is deformed to accommodate the shape of the sample with minimal air gaps therebetween. Preferably, the deformable surface is provided by a plurality of pins slidably engaged in a pole structure and urged outwardly for contact with and conformance with a non-planar sample surface.

Abstract: In an induction logger, a method for nulling the output signal from a pair of series-coupled receiver coils by altering the magnetic flux distribution within the coils by use of one or more magnetic equalization bodies. The shape and aspect ratio of the equalization body are chosen to minimize temperature dependence of the initial permeability. Alternatively, a highly conductive equalization body may be used.

Abstract: In an apparatus for testing test objects equipped with magnetic properties, the magnetic circuit with an air gap having a detector consists of at least a soft-magnetic material and a permanent-magnetic material, whereby the static magnetic field produced by the permanent-magnetic material penetrates the magnetic circuit. The air gap is preferably formed between an end of the soft-magnetic material and a pole of the permanent-magnetic material.

Abstract: Apparatus and methods are disclosed which provide increased sensitivity, selectivity and dynamic range for non-contact measurement of actual physical and/or kinematic properties of conducting and magnetic materials. The apparatus and methods are based upon various methods for increasing sensitivity, selectivity and dynamic range through proper construction of a magnetometer sensor and for proper selection of operating point parameters for the application. A measurement apparatus for measuring one or more MUT properties includes an electromagnetic winding structure which, when driven by an electric signal, imposes a magnetic field in the MUT and senses an electromagnetic response. An analyzer is provided for applying the electric signal to the winding structure. A property estimator is coupled to the winding structure and translates sensed electromagnetic responses into estimates of one or more preselected properties of the material.

Abstract: A device for and method of testing toroidal magnetic cores for magnetic anomalies which prevent uniform performance of the cores. The core is positioned on a drive device which can rotate the core through 360.degree.. The core passes through an input winding which receives the test signal and an output winding coupled to a display device which shows the presence or absence of such magnetic anomalies.

Abstract: An inspection device has an exciting coil for generating an electromagnetic field and an induction coil which are integrally connected to each other a coaxial relation so as to induce mutual inductance in the induction coil by the electromagnetic field. The mutual inductance caused in the induction coil varies with a given object to be inspected which is present in the electromagnetic field. The object can be inspected by analyzing the change in inductance.

Abstract: Apparatus and process for sorting used batteries and accumulators on the basis of their chemical constitution based on the analysis of the inductive effect produced by the substances which are contained in the battery or accumulator, and whose ferromagnetic properties differ according to their chemical constitution. The measurement process in which the apparatus is used is based on the consecutive application to the excitation circuit of at least two different voltage amplitudes at the same frequency or two different frequencies at the same voltage amplitude.

Abstract: An object detecting device for detecting an object at least partly having a magnetic substance or magnetic-flux permeable material is formed of a detection coil arrangement including a primary coil for generating magnetic flux and a secondary coil disposed separately from the primary coil at a predetermined interval for receiving the magnetic flux from the primary coil; and a detection circuit for detecting an increase of the magnetic flux transmitted to the secondary coil due to presence of the object within a space between the primary and secondary coils. The detection circuit produces signal indicating the presence of the object upon detection of the presence.

Abstract: The sensitivity of an induction-type motion sensor having a magnetic circuit with a permanent magnet to small movements is increased by the use of a stator with a core containing a permanent magnet as a fixed part thereof. An electrical coil is wound around the stator and a pendulum-type rotor has a ferromagnetic moving element which, when the motion sensor is subjected to movement forces, passes in and out of the air gap of the stator, thereby alternating the magnetic field in the stator and inducing a current in the electrical coil.

Abstract: A fluxmeter includes an application unit for applying a magnetic field, a superconducting quantum interference element and a flux transmitting circuit. The flux transmitting circuit includes a pickup coil formed of a superconducting print coil and a core for the pickup coil. The core is formed of a soft magnetic material. The core serves to suppress the leakage of magnetic flux to magnetically couple the pickup coil and the superconducting quantum interference element efficiently to improve the sensitivity and resolution of the fluxmeter. The pickup coil may be manufactured by photolithography, sputtering, laser beam deposition, MBE deposition, MOCVD or spray pyrolysis.

Abstract: A perfected metal detector for passageways, equipped with transmitter-recer Tx-Rx windings connected, using suitable amplifiers A and D, to an Analysis and Control Logic Unit LAC where the signals are compared; and also equipped with at least one corrective receiver winding CC on each side of a supervised passage used to supply information to the LAC unit about metal bodies in transit along paths close to it, with the aim of rendering uniform the interceptive sensivity throughout the transit area, even when more than one metal body is in simultaneous transit.

Abstract: A continuous method of measuring magnetic properties of a strip or sheet of an electrical steel comprises the steps of inducing in the strip or sheet electro magnetic forces and measuring the value of such induced electro magnetic forces by passing the strip or sheet continuously through a flux density detecting search coil. The search coil comprises along a part of its length a jet of fluid electrolyte.