Abstract: A dual core geophone includes a dual magnetic core packaged in a housing providing higher sensitivity and a reduction of electric wires in the device. The geophone includes a locking mechanism for the dual magnetic core to protect the device from strong vibrations when the device is not in use. A method for measuring acoustic vibrations in a downhole with a dual core geophone as above includes locking the dual magnetic core when the geophone is not detecting acoustic vibrations.

Abstract: Disclosed are methods of building Z-graded radiation shielding and covers. In one aspect. the method includes: providing a substrate surface having about medium Z-grade; plasma spraying a first metal having higher Z-grade than the substrate surface; and infusing a polymer layer to form a laminate. In another aspect, the method includes electro/electroless plating a first metal having higher Z-grade than the substrate surface. In other aspects, the invention provides methods of improving an existing electronics enclosure to build a Z-graded radiation shield by applying a temperature controller to at least part of the enclosure and affixing at least one layer of a first metal having higher Z-grade than the enclosure.

Abstract: A device for capacitive sensing includes: a plurality of sensor electrodes, the plurality of sensor electrodes comprising: a plurality of receiver electrodes and a plurality of transmitter electrodes, wherein a transmitter electrode of the plurality of transmitter electrodes comprises a first portion and a second portion with a separation between the first portion and the second portion; and a processing system, configured to: drive the first portion of the transmitter electrode with a transmitter signal, receive a resulting signal corresponding to the first portion of the transmitter electrode via a first receiver electrode of the plurality of receiver electrodes, receive a reference signal corresponding to the second portion of the transmitter electrode via a second receiver electrode of the plurality of receiver electrodes, and determine a modified resulting signal based on the resulting signal and the reference signal.

Abstract: In one aspect, an apparatus is disclosed comprising: a housing; a proof mass movable within the housing; an optical element mounted on one of the housing and the proof mass; a reflective element on the other one of the housing and the proof mass; a light source configured to illuminate grating and minor; and one or more detectors configured to detect light incident from the reflective element and the diffractive element and generate a signal indicative of the relative displacement of proof mass and the housing.

Abstract: Methods and apparatus for cable termination and sensor integration at a sensor station within an ocean bottom seismic (OBS) cable array are disclosed. The sensor stations include a housing for various sensor components. Additionally, the sensor stations can accommodate an excess length of any data transmission members which may not be cut at the sensor station while enabling connection of one or more cut data transmission members with the sensor components. The sensor stations further manage any strength elements of the cable array.

Abstract: This invention relates to an active vibration isolation installation based on electromagnetic and aerostatic floatation which is essential for the super-precision measurement and manufacture. It mainly consists of an isolation platform, an intermediate sleeve and a base. The isolation platform supports any object(s) placed on the platform and is supported by the intermediate sleeve. And the intermediate sleeve is supported on the base which is fixed on the ground. This invention uses the combination electromagnetic and aerostatic floatation to achieve large bearing capacity while excellent vibration isolation performance is maintained. This invention realizes automatic control of stiffness, using closed-loop speed control methods. It is therefore conclude that this invention can impose an excellent inhibitory action on the vibration originating from surroundings and the platform itself.

Abstract: A rotational seismometer having a housing that encases an optical lever having a light source for emitting a beam of light through a slit defined by the optical lever that is focused by a lens for focusing the beam of light to a balance bob suspended within the housing is disclosed. The balance bob includes a mirror secured to a plate attached to the housing through an arrangement that includes a thin fiber attached to a stiff wire such that the stiff wire bends and the thin wire does not bend when a tilt motion is applied to the rotational seismometer.

Abstract: Disclosed are an earthquake monitoring device and a method of installing the same, which can permit stable and efficient installation and operation on any ground surface with free-field conditions including level and sloped ground conditions, and can provide precise monitoring results of earthquakes. The earthquake monitoring device includes a sensor for sensing vibration; and a base having an upper surface formed into a leveled surface, wherein the sensor is secured to the upper surface, and the base is placed on an excavated ground such that the upper surface of the base is positioned on a ground surface or the sensor on the upper surface of the base intersects the ground surface.

Abstract: A micro geophone having pole pieces do not extend out around the sides of the magnet, thereby allowing a reduced geophone diameter for a given magnet diameter. The pole pieces are adhesively bonded to the magnet using an adhesive, which may be made suitably electrically conductive by silver or nickel fillers or non-conductive by mica fillers such as borosilicate glass micro-spheres. Axial space is economized by eliminating traditional spider retaining rings. The spider springs are seated directly against the coil form and secured by adhesive fillets disposed on the outward-facing spring circumferences. The spider springs include circumferential notches to receive adhesive. A two-piece bimetallic coil form of aluminum and a heavier material, joined by adhesive, is provided. Headers are affixed to the housing within the seats by adhesive. A straight or rounded chamfer at each of the geophone ends allows the overall geophone dimensions to be maximized.

Abstract: A micro geophone having pole pieces do not extend out around the sides of the magnet, thereby allowing a reduced geophone diameter for a given magnet diameter. The pole pieces are adhesively bonded to the magnet using an adhesive, which may be made suitably electrically conductive by silver or nickel fillers or non-conductive by mica fillers such as borosilicate glass micro-spheres. Axial space is economized by eliminating traditional spider retaining rings. The spider springs are seated directly against the coil form and secured by adhesive fillets disposed on the outward-facing spring circumferences. The spider springs include circumferential notches to receive adhesive. A two-piece bimetallic coil form of aluminum and a heavier material, joined by adhesive, is provided. Headers are affixed to the housing within the seats by adhesive. A straight or rounded chamfer at each of the geophone ends allows the overall geophone dimensions to be maximized.

Abstract: Methods and systems utilizing seismic sensors configured or designed for use in seismic signal detection. The seismic sensors output displacement signals of a displacement sensor superimposed on velocity signals generated by a moving coil of the seismic sensors.

Abstract: Vibration transducers, sensors including the vibration transducers, and methods for manufacturing the same. The vibration transducer may include a magnet. The vibration transducer may include a bobbin disposed about the magnet. The vibration transducer may include a first coil disposed about the bobbin. The vibration transducer may include a controllable damping coil disposed about the bobbin. The first coil is movable relative to the magnet. The magnet is polarized with respect to the axis of the vibration transducer.

Abstract: An apparatus and a method for detecting vibration are disclosed. The apparatus comprises a housing, a magnetic structure forming a magnetic field in the housing, and a coil structure in the magnetic field, concentric of the magnetic structure. In response to external vibration, the coil structure and the magnetic structure are movable with respect to each other. The coil structure comprises at least two sets of coils overlapped in space, of which a first coil set is for detecting vibration and a second coil set is for applying control in accordance with a control signal.

Abstract: Embodiments of a directional acoustic sensor or acoustic velocity microphone are disclosed that include a sensor frame structure, a support means, and a buoyant object. The buoyant object is suspended in the sensor frame structure using the support means. The buoyant object has a feature size smaller than a wavelength of the highest frequency of an acoustic wave in air. The buoyant object receives three-dimensional movement of the air excited by the acoustic wave. The three-dimensional movement that the buoyant object receives is detected using a detection means. A particle velocity of the acoustic wave is derived from the three-dimensional movement of the buoyant object using the detection means. The detection means can be an optical detection means, an electromagnetic detection means, or an electrostatic detection means. An acoustic image of the acoustic wave can be determined by distributing two or more directional acoustic sensors a multi-dimensional array.

Abstract: A micro geophone having pole pieces do not extend out around the sides of the magnet, thereby allowing a reduced geophone diameter for a given magnet diameter. The pole pieces are adhesively bonded to the magnet using an adhesive, which may be made suitably electrically conductive by silver or nickel fillers or non-conductive by mica fillers such as borosilicate glass micro-spheres. Axial space is economized by eliminating traditional spider retaining rings. The spider springs are seated directly against the coil form and secured by adhesive fillets disposed on the outward-facing spring circumferences. The spider springs include circumferential notches to receive adhesive. A two-piece bimetallic coil form of aluminum and a heavier material, joined by adhesive, is provided. Headers are affixed to the housing within the seats by adhesive. A straight or rounded chamfer at each of the geophone ends allows the overall geophone dimensions to be maximized.

Abstract: A micro geophone having pole pieces do not extend out around the sides of the magnet, thereby allowing a reduced geophone diameter for a given magnet diameter. The pole pieces are adhesively bonded to the magnet using an adhesive, which may be made suitably electrically conductive by silver or nickel fillers or non-conductive by mica fillers such as borosilicate glass micro-spheres. Axial space is economized by eliminating traditional spider retaining rings. The spider springs are seated directly against the coil form and secured by adhesive fillets disposed on the outward-facing spring circumferences. The spider springs include circumferential notches to receive adhesive. A two-piece bimetallic coil form of aluminum and a heavier material, joined by adhesive, is provided. Headers are affixed to the housing within the seats by adhesive. A straight or rounded chamfer at each of the geophone ends allows the overall geophone dimensions to be maximized.

Abstract: A micro geophone having pole pieces do not extend out around the sides of the magnet, thereby allowing a reduced geophone diameter for a given magnet diameter. The pole pieces are adhesively bonded to the magnet using an adhesive, which may be made suitably electrically conductive by silver or nickel fillers or non-conductive by mica fillers such as borosilicate glass micro-spheres. Axial space is economized by eliminating traditional spider retaining rings. The spider springs are seated directly against the coil form and secured by adhesive fillets disposed on the outward-facing spring circumferences. The spider springs include circumferential notches to receive adhesive. A two-piece bimetallic coil form of aluminum and a heavier material, joined by adhesive, is provided. Headers are affixed to the housing within the seats by adhesive. A straight or rounded chamfer at each of the geophone ends allows the overall geophone dimensions to be maximized.

Abstract: A method includes enabling a power supply of a ground sensor device to provide power to one or more components of the ground sensor device based on one or more rotations of a rotor of the ground sensor device.

Abstract: Methods and systems utilizing seismic sensors configured or designed for use in seismic signal detection. An electrical current is applied to a seismic sensor such that the moving coil is located at a neutral position relative to the magnetic field in the seismic sensor to compensate for gravitational acceleration.

Abstract: A geophone in which a coil bobbin assembly ideally includes a provision for receiving a third coil winding between the upper and lower coils. A third mass-tuning coil is wound around the bobbin whose purpose is to adjust the overall mass of the bobbin assembly with greater accuracy and precision than can be achieved by machining techniques alone. Mass is adjusted by adding or subtracting one or more turns of wire in the tuning coil. The tuning coil is preferably electrically shorted for increasing geophone damping.

Abstract: Methods and systems utilizing seismic sensors configured or designed for use in seismic signal detection. An electrical current is applied to a seismic sensor such that the moving coil is located at a neutral position relative to the magnetic field in the seismic sensor to compensate for gravitational acceleration.

Abstract: Methods and systems utilizing seismic sensors configured or designed for use in seismic signal detection. The seismic sensors output displacement signals of a displacement sensor superimposed on velocity signals generated by a moving coil of the seismic sensors.

Abstract: A geophone utilizing an Alnico-9 magnet and having an improved sensitivity over Alnico-9 geophones of prior art through the lengthening of the parasitic air gap between the upper and lower pole pieces which, results in less magnetic flux leakage. The flux concentration through the geophone coils is increased and shifted towards the ends of the magnet. The increase of sensitivity of geophone of the present invention over prior art geophones may exceed 3 dB. The axial length of the coil bobbin is increased, and the positions of the electrical coils are moved towards the ends of the magnet to align with the shifted magnetic flux.

Abstract: Methods and systems for determining coil eccentricity of seismic sensors configured or designed for use in seismic signal detection. A direct electrical current is applied to a moving coil of a seismic sensor such that the moving coil is dislocated from a neutral position relative to the magnetic field in the seismic sensor. A predetermined indicator is measured and eccentricity of the coil (?) relative to the center of the magnetic filed is determined using the predetermined indicator.

Abstract: The present invention provides a sensory signal output apparatus, which is constructed such that several frequencies of output can be realized. The sensory signal output apparatus includes a coil (15), to which an alternating signal is transmitted, a magnetic circuit (11) including a magnet (1 Ia), a top plate (1 Ib) and a yoke (1 Ic) to form an opening such that magnetic flux linkage perpendicular to the coil is induced, and a casing (1) receiving the magnetic circuit therein. The sensory signal output apparatus further includes a first vibration unit (10a) having the magnetic circuit, which responds to a magnetic field depending on a direction of the input signal, thus vibrating, and a first vibrating screen (13) adhered or welded to a ring-shaped protrusion of the yoke, thus generating a sensory signal.

Abstract: Methods and systems for determining coil eccentricity of seismic sensors configured or designed for use in seismic signal detection. A direct electrical current is applied to a moving coil of a seismic sensor such that the moving coil is dislocated from a neutral position relative to the magnetic field in the seismic sensor. A predetermined indicator is measured and eccentricity of the coil (?) relative to the center of the magnetic filed is determined using the predetermined indicator.

Abstract: A geophone in which a coil bobbin assembly ideally includes a provision for receiving a third coil winding between the upper and lower coils. A third mass-tuning coil is wound around the bobbin whose purpose is to adjust the overall mass of the bobbin assembly with greater accuracy and precision than can be achieved by machining techniques alone. Mass is adjusted by adding or subtracting one or more turns of wire in the tuning coil. The tuning coil is preferably electrically shorted for increasing geophone damping.

Abstract: A geophone utilizing an Alnico-9 magnet and having an improved sensitivity over Alnico-9 geophones of prior art through the lengthening of the parasitic air gap between the upper and lower pole pieces which, results in less magnetic flux leakage. The flux concentration through the geophone coils is increased and shifted towards the ends of the magnet. The increase of sensitivity of geophone of the present invention over prior art geophones may exceed 3 dB. The axial length of the coil bobbin is increased, and the positions of the electrical coils are moved towards the ends of the magnet to align with the shifted magnetic flux.

Abstract: Methods and systems utilizing seismic sensors configured or designed for use in seismic signal detection. An electrical current is applied to a seismic sensor such that the moving coil is located at a neutral position relative to the magnetic field in the seismic sensor to compensate for gravitational acceleration.

Abstract: A seismic sensor comprising a coil assembly suspended in a magnet field produced by a magnet assembly, and a locking mechanism for preventing the coil assembly from moving freely until a seismic event is initiated at the surface or within an earth formation to collect seismic data.

Abstract: A seismic sensor comprising a coil assembly suspended in a magnet field produced by a magnet assembly, and a locking mechanism for preventing the coil assembly from moving freely until a seismic event is initiated at the surface or within an earth formation to collect seismic data.

Abstract: A sensor assembly includes a seismic sensor element and a shell. The shell at least partially surrounds the sensor element to shield the sensor element from a magnetic field that is generated outside of the shell.

Abstract: The method and the apparatus disclosed serve to acquire seismic induced movements. A coil and a permanent magnet are contained in an enclosure and the seismic movements induce a relative movement between said coil and said magnet. The current induced into the coil is appraised as a measure of said seismic movement. The position of the coil in relation to the permanent magnet is monitored by a position sensor. A closed loop control generates a current that is fed into the coil so that the coil settles at a given neutral position relative to the permanent magnet.

Abstract: A vibration transducer such as a geophone, comprising a central pole piece (110) with a magnet (112) and coil (118) concentrically arranged around it. The position of the magnet (112) is fixed relative to the pole piece (110) and the coil (118) is movable relative to the magnet (112). A method of manufacturing a vibration transducer is characterised in that a bobbin carrying the coils is formed from a substantially tubular body which is positioned on a mandrel and at least one coil is wound around its outer surface, the mandrel being removed from the bobbin when the coil is complete. Another method is characterised in that the coil is formed separately and the bobbin is formed from a substantially tubular body which is positioned inside the coil and expanded to contact the coil when in position.

Abstract: A geophone including conductive terminals positioned on opposite sides of the geophone housing. The geophone includes a pair of coils resiliently mounted within the geophone housing and a magnet. A first end plate, a first spring, and a first coil support provide a first end of the electrically conductive path. A second end plate, a second spring, and a second coil support provide a second end of the electrically conductive path. The first and second end of the electrically conductive path are electrically insulated from each and the geophone housing. Providing one or more remaining components with electrically non-conductive surfaces provides electrical insulation.

Abstract: A transducer (1) with a transducer axis (2), with a membrane (3), with a magnet system (6) having an outer magnet system part (7) and an inner magnet system part (8), with a moving coil configuration (27) connected to the membrane (3) and having a coil carrier (28) and a moving coil (29) held by the coil carrier (28) in an air gap (14) between the two magnet system parts (7, 8), and with guide means (36) for a rectilinear guidance of the moving coil configuration (27) parallel to the transducer axis (2), wherein the moving coil configuration (27) has a cylindrical boundary surface (42) which together with a cylindrical boundary surface (15) of the outer magnet system part (7) delimits a cylindrical gap (43) which is acoustically impermeable above a lower limit frequency of at most 100 Hz.

Abstract: Force-balance feedback geophone apparatus and methods for characterization of the geophone apparatus. Control inputs (65) provide for switching (61, 63) of a force-balance feedback geophone between operational states, thereby allowing for in situ determination of geophone characteristics. Feedback circuit modification provides for increased bandwidth and a series RC circuit in the reference resistance provides for increased damping without significantly affecting low frequency performance.

Abstract: Systems and methods of the invention can equalize the pressure between an interior cavity and an environment exterior to the interior cavity, while providing for acoustic isolation between the two environments so that acoustic energy propagating through one environment does not cause acoustic vibrations in the other environment. In one application, these pressure compensation systems are employed to equalize the pressure on either side of a moving coil projector, thereby reducing the deleterious effect that a pressure differential across the moving coil projector can have on the operation of the moving coil projector and reducing the likelihood that propagating acoustic energy can result in phase cancellation that reduces the acoustic performance of the moving coil projector.

Abstract: A device which picks up elastic waves, such as a geophone for example, in positions far from the natural operating position for which it is designed. The device comprises an electrodynamic pickup including a magnet (1), a moving coil (2) placed in the magnetic field, springs (4) suited to hold the coil in a well-centered static position when the axis thereof is parallel to a selected reference direction (horizontal or vertical, for example) and a current source which applies to the coil an electrical current which corrects any unbalance of the coil in relation to the static position thereof due to an inclination of the axis of the coil in relation to the reference direction. The current source may be for example a source of direct current (5) and a voltage divider (P) whose division factor depends on the angle between the axis of the pickup and a reference axis or a compensating device suited to minimize the distortion ratio of the geophone.

Abstract: The invention converts a conventional velocity geophone to a force-balance accelerometer. A single, spring supported geophone coil, in conjunction with a permanent magnet assembly fixed to the geophone housing, is used as both an electromagnetic velocity sensor and a force actuator. An electronic circuit is used to implement a force-balance feedback control system. The electromotive force associated with the velocity of the coil is detected and used as an input to the feedback control system. The output of the control system is applied to the same coil in such a manner as to provide negative feedback. In the presence of accelerations, the coil velocity with respect to the geophone housing is reduced essentially to zero. Thus, the force related to the external acceleration acting on the coil-mass, is balanced by the applied force. Specifically, the current applied by the control system to the same coil is proportional to the acceleration of the housing.

Abstract: An earthquake detector including a platform fixedly coupleable to a recipient surface for receiving vibrations generated as a result of an earthquake; a spring-loaded frame secured to the platform; an alarm mechanism coupled to the spring-loaded frame for providing an alarm when the platform and frame are shaken; and a counterweight coupled to the frame for damping its vibration.

Abstract: A geophone is disclosed that has a cylindrical housing closed at one end by a bottom and the other end by a top. A magnet assembly of a rare earth magnet with pole pieces at each end of the magnet is centrally mounted in the housing providing an annular space between the magnet assembly and the housing. A coil form is located in the annular space. Springs support the coil form for axial movement relative to the magnet assembly along the longitudinal axis of the housing. The rare earth magnet produces a magnetic field sufficiently strong that the pole pieces can be made longer than the coils on the coil form thereby provided a uniform magnetic field in which the coils move thereby reducing the amount of harmonic distortion produced by the geophone.

Abstract: A variable reluctance acoustic projector includes a piston structure that provides rigid retention and precise alignment of electromagnetic cores within the projector housing. The piston structure provides a pair of metallic piston blocks having cavities in which the electromagnetic cores are mounted. The piston blocks rigidly retain the electromagnetic cores within the cavities by compressive loading, improving the structural reliability of the device. In addition, the piston blocks enable precise alignment and orientation of the pole faces of opposing electromagnetic cores parallel to one another. Flexure ribs formed in the piston blocks increase the compliance of the blocks to substantially confine motion of the piston blocks to translation along a single axis of actuation during excitation of the electromagnetic cores.

Abstract: An electromechanical transducer having permanent magnet means forming a bias field in a region between poles, and a vibratable armature having a first part in that region. The armature has a second part extending from the first part substantially externally of that region. Magnetically permeable structure includes a portion opposing the second part across a transverse gap. The latter structure is included in a closed magnetic loop comprising said first and second parts, a working gap in said region and the transverse gap, and an electrical signal coil is threaded by the loop.

Abstract: An electrically driveable shockwave source for generating acoustic shockwaves of the type suitable for medical therapy, as a coil arrangement and a membrane disposed adjacent the coil arrangement. The membrane and/or the coil arrangement is formed by a multi-layer structure, with each layer having electrically conductive elements therein insulated from each other, in the form of electrically conductive sections in the membrane, or electrically conductive windings connected in parallel in the coil arrangement.

Abstract: A sonar projector having a pair of opposed oscillating pistons driven by an electromagnetic assembly is provided with reduced weight and high power by forming the electromagnetic assembly with a permanent magnet structure consisting of two coaxial longitudinally juxtaposed members each having permanent magnets radially poled oppositely to the permanent magnets of the other coaxial member, each of the permanent magnets of one coaxial member forming a series magnetic circuit with one of the permanent magnets of the other coaxial member. As a result of this arrangement, the amount of iron required for pole pieces of the electromagnetic assembly is reduced without reducing power. Furthermore, the size or volume is also reduced as compared to an equivalent projector.

Abstract: A geophone system for measuring mechanical vibrations such as seismic waves include a mechanical transducer with an electronic processing circuit. The mechanical transducer includes an inertial mass adapted to be excited by an input acceleration signal and by a force transducer. The excitation is detected by a sensor element and the processing circuits of the geophones control the force transducer and are connected with a central station via a transmission line.

Abstract: A noise cancelling watertight transducer that converts sound wave to electromagnetic waves or conversely electromagnetic waves to sound waves comprises a hollow shell having curved walls mounted for movement in a resilient container. A freely movable inertial mass is located inside said shell. The inertial mass resists movement when a force is applied thereto. Signal translating means are incorporated therein consisting of either an electromagnetic device, a piezoelectric element or voltage potential senative element that is mounted in and connected with said shell and interacts with said inertial element. In response to appropriate signal some embodiments of the instant invention acts as a bidirectional device converting electrical signal to acoustical signal or conversely acoustical signal to electrical signal.

Abstract: An underwater transducer system reproduces high-fidelity audio signals underwater, and detects and monitors low levels of sound activity, both adjacent to a body of water such as a swimming pool, and in the water. The system includes an underwater housing for a diaphragm that directly contacts the water, a coil assembly movable within the housing and rigidly connected to the center of the diaphragm by a tubular member of the coil assembly engaging a cylindrical boss portion of the diaphragm. The housing can be suspended by an elongated cord member from a wall coping, or mounted within a wall fixture structure. The system can have a source of illumination, a conduit from the source terminating in the housing on the coil axis proximate the diaphragm, and an optical element sealingly protrudes the diaphragm for transmitting light-amplified illumination into the water.

Abstract: An electromagnetic transducer for use in generating transient acoustic pulses in particular for medical purposes such as the destruction of kidney stones. The transducer comprises at least one pair of conductors, of which one is held against movement by a carrier having a high sonic impedance, whereas the other is displaceable with respect to the first to actuate an emitter for generating a pressure pulse as soon as both conductors are traversed by contradirectionally oriented currents so as to repel one another. The conductors of each pair are laid parallel to each other and so connected electrically that the portions adjacent to each other in each case of the cooperating first and second conductors can be traversed by the currents fed into the conductors contradirectionally to generate repulsive forces and equidirectionally to generate attractive forces.