Abstract:
An apparatus includes a coil suspended in a magnetic field and an optical detector to detect displacement of the coil in response to a stimulus. The apparatus further includes a feedback circuit to program a gain of the sensor, wherein the feedback circuit is coupled to the optical detector and to the coil.
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:
An apparatus includes a coil suspended in a magnetic field, and an optical detector to detect displacement of the coil in response to a stimulus. The apparatus further includes a feedback circuit coupled to the optical detector and to the coil. A coil constant of the apparatus may be configured to a desired value.
Abstract:
An apparatus includes a network of switchable coils suspended in a magnetic field, wherein a topology of the network of switchable coils may be configured to change at least one characteristic of a sensor, and an optical detector to detect displacement of the coil in response to a stimulus. The apparatus further includes a feedback circuit coupled to the optical detector and to the network of switchable coils.
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:
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 long-period vibration sensor includes an overdamped accelerometer including a magnet fixed to the inside of a casing, a detection coil disposed between magnetic poles formed due to the magnet, a bobbin configured to hold the detection coil, and a support spring configured to support the bobbin in the casing so that the bobbin can vibrate in a predetermined direction, a voltage being outputted from the detection coil when the bobbin is damped, a plurality of digital filters having different frequency characteristics from one another, a selection module configured to select one digital filter from the plurality of digital filters based on an output value of the voltage outputted from the overdamped accelerometer, and a correction module configured to correct the output value of the voltage outputted from the overdamped accelerometer using the digital filter selected by the selection module.
Abstract:
A closed loop broadband geophone which is made by using a high performance method to measure a mechanical vibration is disclosed. All coil portions of the two or more coil sets are located in at least 4 separate recesses of the bobbin. Each coil portion of these coil sets has an individual magnetic field magnitude using Faraday's Law and Lorentz's Law. This mathematic method, significantly improves the accuracy of both measuring the mechanical vibration and providing feedback control to the sensor coils. These coil sets are connected to an electronic device which processes the measuring signal and a feedback signal to the sensing coil as a precision digital forcing signal for a reference position.
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.