Abstract: A fiber optic sensing system is provided. The fiber optic sensing system includes: at least one fiber optic transducer; an optical backscatter interrogator for interrogating backscatter optical signals from the at least one fiber optic transducer; and an optical fiber between the optical backscatter interrogator and the at least one fiber optic transducer.

Abstract: A remotely actuated clamping device for a borehole seismic sensing system. The remotely actuated clamping device includes a clamping mechanism configured to engage a surface of a borehole by actuation of the clamping mechanism. The remotely actuated clamping device also includes a fluid based actuator configured to actuate the clamping mechanism. The fluid based actuator includes a chamber configured to be kept at a pressure that is isolated from an ambient pressure of the borehole. The fluid based actuator also includes a piston within the chamber. The chamber receives a pressurized fluid to move the piston within the chamber to actuate the clamping mechanism. The pressure used to actuate the clamping mechanism is independent of the ambient pressure of the borehole. Also disclosed are methods of operating the device.

Abstract: A fiber optic sensing system is provided. The fiber optic sensing system includes: at least one fiber optic transducer; an optical backscatter interrogator for interrogating backscatter optical signals from the at least one fiber optic transducer; and an optical fiber between the optical backscatter interrogator and the at least one fiber optic transducer.

Abstract: A fiber optic sensing system. The fiber optic sensing includes an optical source and a lead cable for receiving an optical signal from the optical source. The fiber optic sensing system also includes a sensor array for receiving the optical signal from the lead cable. The sensor array includes a plurality of fiber optic sensors, each of the plurality of fiber optic sensors including an interferometer having two legs. The plurality of fiber optic sensors includes a noise compensation sensor. Each of the legs of the interferometer of the noise compensation sensor is configured to sense vibration in substantially the same manner.

Abstract: A remotely actuated clamping device for a borehole seismic sensing system. The remotely actuated clamping device includes a clamping mechanism configured to engage a surface of a borehole by actuation of the clamping mechanism. The remotely actuated clamping device also includes a fluid based actuator configured to actuate the clamping mechanism. The fluid based actuator includes a chamber configured to be kept at a pressure that is isolated from an ambient pressure of the borehole. The fluid based actuator also includes a piston within the chamber. The chamber receives a pressurized fluid to move the piston within the chamber to actuate the clamping mechanism. The pressure used to actuate the clamping mechanism is independent of the ambient pressure of the borehole. Also disclosed are methods of operating the device.

Abstract: An array of fiber optic hydrophones or geophones is formed by winding of optical fiber around a continuous, yet flexible cylindrical core. The cylindrical core contains an elastomer filled with a specified percentage of voided plastic microspheres. The elastomer provides the necessary radial support of the optical fiber, and with the included voided microspheres, provides sufficient radial compliance under acoustic pressure for proper operation of the hydrophone. The cylindrical core can be made in very long sections allowing a plurality of fiber optic hydrophones to be wound onto it using a single optical fiber, with individual hydrophone elements separated by integral reflectors such as Fiber Bragg Gratings (FBSs). The center of the core may include a strength member and a central hollow tube for the passing of additional optical fibers. The aforementioned hydrophone array is then packaged within a protective outer coating or coatings as required for the specified application.

Abstract: A pair of fiber optic coils are mounted on opposite sides of a flexural disk and are arranged to form an interferometer that produces an output signal in response to acceleration of the flexural disk. The flexural disk is mounted in a housing having first and second end plates with a sidewall extending between them. A support member extends between the end plates and through a central passage in the flexural disk. A pair of compressive dampers is mounted in the housing between the flexural disk and the housing end plates. A shear damper mounted on the central support member exerts a radial force on an inner edge of the central passage in flexural disk to dampen vibrations of the flexural member and control the output signal amplitude over a selected frequency range.

Abstract: An accelerometer of the type in which a disk is mounted upon a vertical post. The accelerometer may be employed as a hydrophone, for example, including a watertight case, and forming a neutrally buoyant structure or may be suitable for hull-mounting. The disk comprises a planar honeycombed structure. A solid, dense ring-like peripheral mass is fixed to the central honeycombed structure to form a composite apparatus. The honeycombed central structure contributes enhanced stiffness without a corresponding increase in weight when compared with disks of solid fabrication while the peripheral concentration of mass increases radius of gyration sufficiently to offset gain dimunition due to increased stiffness so that an increase in figure of merit is obtained.

Abstract: A telemetry harness for a hydrophone array which carries and positions the signal carrying elements of the array for ready assembly and reconfiguration. An elongated fabric incorporates bare optical fibers as well as optical and electrical cables and tension-resistant strength members. The fiber is characterized by markings, fiber slackness and apertures at predetermined locations that assist an assembler in determining where to cut selected bare fibers for splicing. The harness is wrapped around a layer of open cell foam that surrounds the aligned and linked sensors of an array segment with the resultant locations of the various sensors in resultant registration with the appropriate overlying fibers of the harness.

Abstract: A fiber optic displacement sensor includes a flexural disk assembly affixed to a mounting post that extends from a support base that is enclosed by a housing. Spiral wound optical fiber coils are mounted on opposite sides of the flexural disk with optical fiber leads extending from both the inner and outer diameters of the optical fiber coils and being optically coupled together to form an interferometer. An inertia ring connected to the periphery of the flexural disk has a plurality of peripheral slots therein for routing the optical fiber leads from the optical fiber coils to other components in the housing. The slots in the inertia ring are arranged to allow differing lengths of fiber to be wound circumferentially in different depth slots to accommodate mismatches in optical fiber lead lengths.

Abstract: A pair of fiber optic coils are mounted on opposite sides of a flexural disk and are arranged to form an interferometer that produces an output signal in response to acceleration of the flexural disk. The flexural disk is mounted in a housing having first and second end plates with a sidewall extending between them. A support member extends between the end plates and through a central passage in the flexural disk. A pair of compressive dampers is mounted in the housing between the flexural disk and the housing end plates. A shear damper mounted on the central support member exerts a radial force on an inner edge of the central passage in flexural disk to dampen vibrations of the flexural member and control the output signal amplitude over a selected frequency range.

Abstract: A fiber optic sensor comprises a flexural disk having a pair of fiber optic coils mounted on opposite sides thereof and connected together to form an interferometer that produces an output signal in response to acceleration of the flexural disk. The flexural disk is mounted in a housing having first and second end plates with a sidewall extending between them. The sidewall is formed to have an inwardly facing groove in which an outer edge portion of the flexural disk is mounted. A support member extends between oppositely facing portions of the first and second end plates and through a central passage in the flexural disk. A damping member is mounted on the central support member and arranged to exert a radial force on an inner edge of the central passage in flexural disk to dampen vibrations of the flexural disk and control the sensor output signal amplitude over a selected frequency band in order to maximize dynamic range.

Abstract: A fiber optic sensor comprises a flexural disk having a pair of fiber optic coils mounted on opposite sides thereof and connected together to form an interferometer that produces an output signal in response to acceleration of the flexural disk. The flexural disk is mounted in a housing having first and second end plates with a sidewall extending between them. The sidewall is formed to have an inwardly facing groove in which an outer edge portion of the flexural disk is mounted. A support member extends between oppositely facing portions of the first and second end plates and through a central passage in the flexural disk. A damping member is mounted on the central support member and arranged to exert a radial force on an inner edge of the central passage in flexural disk to dampen vibrations of the flexural disk and control the sensor output signal amplitude over a selected frequency band in order to maximize dynamic range.

Abstract: Interconnection mechanisms for a laser gyroscope assembly (10) enable it to be rapidly and non-harmfully assembled and disassembled prior to a more durable interconnection, to facilitate repair and rework. The assembly includes a fiber optic spool (12), an inner shield (16) and an outer shield (18), which are formed of a stress-annealed magnetic and generally malleable material. The outer shield comprises upper and lower portions or parts (30, 32) whose first and second end segments (62, 66) respectively terminate the portions. Segment (66) has angled intersecting conical surfaces (74, 76) which engage surfaces (65, 67) on segment (62). Stops (80, 83) are formed respectively on the ends of the segments so that a distal end (68) contacts an interior ledge surface (80) of outer shield (34), thereby to limit the mutual engagement and to center the segment configuration interfit.

Abstract: An accelerometer of the type in which a disk is mounted upon a vertical post. The accelerometer may be employed as a hydrophone, for example, including a watertight case, and forming a neutrally buoyant structure or may be suitable for hull-mounting. The disk comprises a planar honeycombed structure. A solid, dense ring-like peripheral mass is fixed to the central honeycombed structure to form a composite apparatus. The honeycombed central structure contributes enhanced stiffness without a corresponding increase in weight when compared with disks of solid fabrication while the peripheral concentration of mass increases radius of gyration sufficiently to offset gain dimunition due to increased stiffness so that an increase in figure of merit is obtained.

Abstract: Modular apparatus for packaging and interfacing a planar photodiode with an optical fiber terminated in a ferrule. An elongated terminal pin protrudes from a header of a generally-cylindrical housing. The ferrule end of the fiber is received at the opposed end of the housing and aligned with a disk-shaped photodetector fixed to the end of the pin interior to the housing. A wire is bonded to a surface of the photodetector and, via the conductive casing of the header, to the housing to provide a miniaturized single-pin pigtailed modular arrangement that is readily adaptable for automated manufacturing process.

Abstract: Single and multi-level structures provide neatly organized, secure and easily repairable optical fiber connections between a pump source laser diode (54) and optical fiber coils represented by x-axis coil (22), y-axis coil (24) and z-axis coil (26). The structures employ specially organized trays (60, 62) for supporting such components as a 1×3 fiber optic coupler (46), an optical isolator (ISO) (48), a wavelength division multiplexer (WDM) (50), a doped fiber coil (52) and a tap coupler (56), and for holding and routing the optical fibers coupled to and between the components. Routing and secure holding of the fibers are facilitated by a built-in optical fiber holder (120), integral with tray (60), and individual optical fiber holders (140), which are stackable upon the built-in holder or upon each other.

Abstract: A fiber optic displacement sensor includes a flexural disk assembly affixed to mounting post that extends from a support base. The flexural disk assembly is mounted in a housing. Spiral wound optical fiber coils are mounted on opposite sides of the flexural disk with optical fiber leads extending from both the inner and outer diameters of the optical fiber coils. Optical signals output from the coils are coupled together to form an interferometer. An inertia ring connected to the periphery of the flexural disk. has a plurality of peripheral slots therein for routing the optical fiber leads from the first and second optical fiber coils to other components in the housing. The inertia ring has curved side edges formed such that the optical fiber leads may be spiral wound thereon between the first and second coils and the peripheral slots to prevent damage to the optical fiber leads from sharp bends.

Abstract: An optical waveguide is formed on a first side of an integrated optics substrate. The optical waveguide is included in a first arm of an interferometer that is arranged to produce an interference pattern. The integrated optics substrate is mounted and arranged such that acceleration of the integrated optics substrate along a selected axis produces a change in the interference pattern. Changes in the interference pattern are monitored and correlated with the acceleration.

Abstract: A temporary latchable or clasping interengageable interconnection mechanism is provided for an optical gyroscope assembly (10) to enable it to be rapidly and non-harmfully assembled and disassembled prior to a more durable interconnection, to facilitate repair and rework. The assembly includes a fiber optic spool (12), an inner shield (16) and an outer shield (18), which are formed of a stress-annealed magnetically permeable, and generally malleable material. Should the assembly be dropped, bent or dented, their magnetic shielding properties will be compromised, which is the harm to be avoided by the temporary interconnection. Accordingly, the fiber optic spool (12) and the inner shield (16) are temporarily interconnectable with the outer shield (18) and its spacer ring (38) by interengageable elements having the ability to latch or clasp the shield and the spacer ring together to prevent or, at a minimum, resist disassembly therebetween.