Abstract: A seismic sensing device has a light source, detection measuring and processing device in combination with an optical seismic sensor reconfigurable array. The light source, detection measuring and processing device provides a selective optical signal to the optical seismic sensor reconfigurable array, and responds to an optical seismic sensor reconfigurable array signal, for providing information about a seismic force to be sensed. The optical seismic sensor reconfigurable array responds to the selective optical signal, and responds to the seismic force, for providing an optical seismic sensor reconfigurable array signal containing information about the seismic force over at least one selective length of the optical seismic sensor reconfigurable array. The optical seismic sensor reconfigurable array includes an optical fiber having optical seismic sensors, each having at least one sensor coil arranged between a respective adjacent Fiber Bragg Grating partial reflector pair having a selectable wavelength.

Abstract: Distributed selectable fiber optic sensing system include a plurality of fiber grating sensors 12 connected to an optical fiber 10 and installed in an oil/gas well 15 and an instrumentation box 20 at the surface which selects which of the sensors 12 to activate, or provide output data from to a display 26 or to a remote link 32, such as the internet. The box 20 has a transceiver/converter 22 which provides a source optical signal 14 and receives a return optical signal 16,18 and which converts the return signal 16,18 to a signal indicative of the parameters being measured by the sensors 12. A sensor selection signal is provided from the remote link 32, the keyboard 28 to the converter 22 which is indicative of which of the sensors 12 to be selected to provide output data for. The end user only pays for the sensors 12 that are selected.

Abstract: The present invention provides a seismic sensing system having at least one sensor, transducer, optical source and detection unit, optical fiber and measurement unit. The sensor responds to a seismic disturbance, for providing a sensor signal containing information about the seismic disturbance. The sensor may be a geophone that detects vibrations passing though rocks, soil etc, and provides an electrical voltage sensor signal. The transducer responds to the sensor signal, for providing a transducer force containing information about the sensor signal. The transducer may be a piezoelectric, magnetostrictive or electrostrictive transducer. The optical source provides an optical signal through the fiber. The optical fiber responds to the transducer force, changes an optical parameter or characteristic of the optical signal depending on the change in length of the optical fiber, for providing a transduced optical signal containing information about the transducer force.

Abstract: A method and apparatus for forming a Bragg grating using a high intensity light includes a pair of focussed writing beams 26,34 that simultaneously intersect and interfere with each other at a region 30 of a photosensitive optical fiber 28. The beams 26,34 have a high intensity (e.g., at least about 500 mjoules/cm2) and pass through an interface medium 50 that is substantially transparent to the wavelength of the writing beams 26,34. The medium has a thickness T set such that the intensity of the beams at the surface 56 of the medium 50 is below an surface damage intensity such that no ablations occur on the fiber 28 or the surface 56 when the fiber 28 is exposed to the beams 26,34.

Abstract: A dynamic pressure sensor with measures for its operation in high temperature and high pressure environments. The sensor uses at least one winding about a deformable mandrel of an optical fiber inscribed by a Bragg grating at its beginning and another at the end of the winding. To counter the effects of high ambient static pressure and temperature, various steps are taken: the mandrel is filled with a high-viscosity low bulk modulus fluid, such as a silicone fluid, and is provided with a baffle system that regulates the flow of the fluid between spans around which the optical fiber is wound. The baffle system is based either on protuberances on a core rod inserted into the mandrel and a system of pinhole size passageways through the protuberances, or based on an open cell foam or fibrous material located on a core rod within a span covered by a stiff jacket. In addition, in high pressure gradient applications, the mandrel is pinched off at different locations along its length.

Abstract: The invention provides a select trigger or detonation system featuring an optical source, an optical fiber, one or more optical couplers and one or more light trigger or detonation devices. The an optical source provides an optical signal containing information about triggering or detonating a respective device. The optical fiber has one or more fiber Bragg Gratings for providing one or more fiber Bragg Grating optical trigger or detonation signals, each having a respective optical trigger or detonation wavelength. The one or more optical couplers each respond to the one or more fiber Bragg Grating optical trigger or detonation signals depending on the respective optical trigger or detonation wavelength, for providing a respective coupled fiber Bragg Grating optical trigger or detonation signal.

Abstract: A compression-tuned bragg grating includes a tunable optical element 20,600 which includes either an optical fiber 10 having at least one Bragg grating 12 impressed therein encased within and fused to at least a portion of a glass capillary tube 20 or a large diameter waveguide grating 600 having a core and a wide cladding. Light 14 is incident on the grating 12 and light 16 is reflected at a reflection wavelength &lgr;1. The tunable element 20,600 is axially compressed which causes a shift in the reflection wavelength of the grating 12 without buckling the element. The shape of the element may be other geometries (e.g., a “dogbone” shape) and/or more than one grating or pair of gratings may be used and more than one fiber 10 or core 612 may be used. At least a portion of the element may be doped between a pair of gratings 150,152, to form a compression-tuned laser or the grating 12 orgratings 150,152 may be constructed as a tunable DFB laser.

Abstract: A pressure transducer using as a component for changing shape in response to a change in the pressure being measured a composite elongated body, with specially arranged reinforcing fibers. Such a pressure transducer can use various means for sensing the change in shape of the elongated body, including an optical fiber affixed to the elongated body so as to itself change in length in response to a change in pressure, and having a Bragg grating as part of the optical fiber, with the Bragg grating positioned and arranged so as to convey, in response to an optical signal, information about the change in shape of the elongated body. The elongated body is provided with at least one pair of contra-helically wound reinforcing fibers, which may even be bi-axially braided, and are wound either to amplify the effect of pressure acting on the elongated body or to insulate the elongated body from the effects of pressure and other sources of stress.

Abstract: An accelerometer has a main body in combination with one or more Bragg grating sensors respectively arranged along one or more axes. The main body has a mass that responds to an acceleration, for providing a force having a component in one or more axes. The Bragg grating sensor means responds to the force, and further responds to an optical signal, for providing a Bragg grating sensor signal containing information about the acceleration respectively in one or more axes. The one or more axes may include orthogonal axes such as the X, Y and Z Euclidian axes. In one embodiment, the main body includes a proof mass and a pair of flexure disks, each having an inner ring, an outer ring, and radial splines connecting the inner ring and the outer ring. The proof mass is slidably arranged between the flexure disks. The Bragg grating means has an optical fiber and a Bragg grating sensor arranged therein. A first end of the Bragg grating sensor is fixedly coupled by a first ferrule to the proof mass.

Abstract: A device for providing optical reference signals includes an optical fiber having a reference array formed therein, the array including at least one reference fiber Bragg grating. The array is mounted on a mounting fixture having a low coefficient of thermal expansion. The mounting fixture is in thermal contact with a thermoelectric (TE) element, and a controller controls the temperature of the TE element. A temperature sensor is in thermal contact with the mounting fixture and provides feedback to the controller to control to the temperature of the TE element to thereby maintain the temperature of the mounting fixture at a selected temperature. The other side of the temperature control element is mounting to a heat sink element. The optical fiber is attached to the mounting fixture in a configuration that minimizes any stress or strain in the optical fiber.

Abstract: A system for vertical seismic profiling of an earth borehole includes an optical fiber having a plurality of Bragg grating sensors formed therein, each one of the Bragg grating sensors being tuned to reflect a respective bandwidth of light, each bandwidth having a different respective central wavelength. Each of the Bragg grating sensors are responsive to an input light signal, a static strain, a dynamic strain and a temperature strain for each providing a respective light signal indicative of static and dynamic forces and temperature at a respective sensor location. The physical spacing and wavelength spacing of the Bragg grating sensors are known such that each of the sensing light signals are easily correlated to a specific depth.

Abstract: A pressure sensor capable of measuring pressure in a harsh environment includes at least one intrinsic fiber optic sensor element formed within a core of an optical fiber. A length of the optical fiber containing the sensor element is attached to a pressure sensitive structure. A dimension of the pressure sensitive structure changes in response to changes in the pressure of a pressure field of the environment. The sensor element is responsive to all input signal and to a strain caused by changes in the dimension of the pressure sensitive structure for providing a pressure signal indicative of the pressure. A temperature compensation sensor is also formed in the fiber near the location of the pressure sensor. The temperature sensor is isolated from strain associated with the pressure for providing temperature compensation of the pressure sensor.

Abstract: Lengths of coiled tubing have sensor carrier elements mounted therebetween such that a plurality of sensor carrier elements are positioned along a length of coiled tubing. Each sensor carrier element carriers a sensor implemented with one or more intrinsic fiber optic sensor elements positioned therein for measuring one or more parameters in an environment. The intrinsic fiber optic sensor elements are multiplexed on one or more optical fibers along the length of the coiled tubing thereby forming a length of coiled tubing having a plurality of spaced apart sensors. The optical fiber or fibers positioned along the length of the coiled tubing are positioned in a fiber carrier which protects the fiber or fibers from the harsh environment. The fiber carrier may be interconnected to each of the sensors to isolate the fibers from the harsh environment.

Abstract: A fiber optic sensor includes a sensor element responsive to a property or condition of a material, such a resistivity, capacitance, inductance, frequency, etc., for providing an output voltage signal that is dependent upon the property or condition of the material. The sensor further includes an optical-to-electrical conversion element, such as a photo detector or a solar cell, that converts an optical signal (photo detector driving optical signal) carried by an optical fiber into an electrical signal. The electrical signal is applied to the sensor element, and in response, the sensor element provides the output electrical signal. The output electrical signal is applied to a measurement device, such as a piezoelectric element, having at least one dimension that varies with changes in the output electrical signal.

Abstract: An interferometer array includes a plurality of interferometer sub-arrays, each sub-array including a plurality of interferometers. Each interferometer in a sub-array is implemented with a respective pair of fiber Bragg gratings and a sensing length of optical fiber positioned between the respective pair of fiber Bragg gratings. The fiber Bragg gratings in each respective pair of fiber Bragg gratings have the same characteristic wavelength that is different from the characteristic wavelength of every other pair of fiber Bragg gratings in the sub-array. The sub-arrays are interconnected to minimize the common-wavelength crosstalk between the sensors in the overall interferometer array. In one embodiment, the sub-arrays are connected in series along a common length of optical fiber such that the maximum common-wavelength crosstalk is limited by the number of sub-arrays connected in series.

Abstract: The present invention features an apparatus for detecting a shoulder load between two components in a drill string, comprising a pin connection, a box connection and a washer for sensing tensioning strain force therebetween. The pin connection has coupling means, and the box connection has corresponding coupling means for coupling to the pin connection to form a drill string. The washer is arranged between the pin connection and the box connection. The washer has embedded fiber optic Bragg Grating sensors that respond to a compressive strain shoulder load force when the pin connection is coupled to the box connection, and further responds to a light signal, for providing a compressive strain shoulder load force light signal containing information about a sensed compressive strain shoulder load force between the pin connection and the box connection in the drill string.

Abstract: The present invention features an apparatus that provides an indication of tensioning strain when it is tensioned with respect to a workpiece, comprising either a bolt, stud or fastener together with an embedded fiber optic Bragg Grating sensor. For example, the bolt has a head at one end, threads at the other end and a central bore with a bore wall drilled into at least one end thereof. The bolt responds to a tensioning force applied on the head of the bolt, for providing a tensioning strain force applied inwardly on the wall of the central bore. The fiber optic Bragg Grating sensor is arranged inside the central bore of the bolt and bonded, for example by epoxy, to the central bore wall. The fiber optic Bragg Grating sensor responds to the tensioning strain force, and further responds to a light signal, for providing a fiber optic Bragg Grating sensor light signal containing information about a sensed tensioning strain force on the bolt when the threads are tensioned to the workpiece.

Abstract: The present invention features an apparatus comprising a packer means and a packer pressure sensing means. The packer means inflates to isolate zones in a well, such as an oil well or a gas well. The packer means responds to a material for inflating and providing a packer inflation pressure. The packer pressure sensing means responds to the packer inflation pressure, for providing a sensed packer inflation pressure signal containing information about a sensed packer inflation pressure when the packer is inflated to isolate zones in the oil or gas well. The packer pressure sensing means may include an internal fiber optic Bragg Grating sensor arranged inside the packer means, for providing the sensed internal packer inflation pressure signal. The packer pressure sensing means may also include an external fiber optic Bragg Grating sensor arranged outside the packer means, for providing the sensed external packer inflation pressure signal.

Abstract: A sensor capable of measuring a number of physical parameters in a harsh environment includes a plurality of intrinsic fiber optic sensor elements formed within a core of an optical fiber, the optical fiber being disposed within a capillary tube made of a high strength, corrosion resistant material. The sensor is located at a distal end of the capillary tube, and the capillary tube is mounted in a monitoring location, such as mounted to the casing of an electrically submersible pump (ESP), such that the sensor can be utilized to measure physical parameters, including static and dynamic pressure, temperature, acceleration and acoustic signals, at the monitoring location. Each sensor is constructed such that a reference element, such as a rigid element, isolates a reference location in the optical fiber from mechanically induced strain.

Abstract: A Bourdon tube pressure gauge is mounted for sensing the pressure of a system. The Bourdon tube is connected to at least one optical strain sensor mounted to be strained by movement of the Bourdon tube such that when the Bourdon tube is exposed to the pressure of the system, movement of the tube in response to system pressure causes a strain in the optical sensor. The optical sensor is responsive to the strain and to an input optical signal for providing a strain optical signal which is directly proportional to the pressure. A reference or temperature compensation optical sensor is isolated from the strain associated with the pressure of the system and is responsive to temperature of the system for causing a temperature-induced strain. The reference optical sensor is responsive to the temperature induced strain and the input optical signal for providing a temperature optical signal which is directly proportional to the temperature of the system.