Abstract: A whispering-gallery-mode-based seismometer provides for receiving laser light into an optical fiber, operatively coupling the laser light from the optical fiber into a whispering-gallery-mode-based optical resonator, operatively coupling a spring of a spring-mass assembly to a housing structure; and locating the whispering-gallery-mode-based optical resonator between the spring-mass assembly and the housing structure so as to provide for compressing the whispering-gallery-mode-based optical resonator between the spring-mass assembly and the housing structure responsive to a dynamic compression force from the spring-mass assembly responsive to a motion of the housing structure relative to an inertial frame of reference.

Abstract: In accordance with one aspect of the present invention, a fiber surveillance system for monitoring a pipeline is provided. The surveillance system includes an optical fiber acoustically coupled to the pipeline to detect acoustic signals associated with vibrations or other activity near or from the pipeline. Optical energy is injected into the optical fiber and an optical detector receives an optical return-signal having certain characteristics resulting from vibrations impinging on the optical fiber. An analyzer is configured to determine operating information about the pipeline based on the optical return-signal. Two or more fibers can be acoustically coupled to the pipeline and arranged in varying configurations to yield greater resolution.

Abstract: A magnetically actuated photonic crystal sensor is disclosed. An optical fiber comprises at least one photonic crystal means coupled to a first end thereof, and a magnetic material coupled to the at least one photonic crystal means.

Abstract: In accordance with an aspect of the disclosed technology, a fiber surveillance system includes a single optical fiber, used, for example, in the detection of acoustic signals associated with vibrations or other activity. In one embodiment of the disclosed technology, the fiber is arranged in a two dimensional topology to improve the spatial resolution of the system. With such a topology the spatial monitoring resolution of the surveillance system is significantly improved over systems in which the fiber is deployed in an essentially straight line topology. In a further embodiment of the disclosed technology, two or more such oriented fibers are juxtaposed or overlapped to yield even greater resolution.

Abstract: A vital sign measurement device includes a sensor fixation device, a sensor frame, an optical sensing system, and an output unit. The sensor fixation device is adapted to be placed against an anatomical location of a subject. The optical sensing system includes an optical waveguide, an optical source device to supply optical energy to the optical waveguide, and an optical detector to detect an amount of optical energy exiting the optical waveguide. The optical sensing system is adapted to sense an arterial pulse from the compression or flexing of at least a portion of the optical waveguide resulting in reduction of the amount of light exiting the optical waveguide. The output unit is configured to receive a signal indicative of the amount of light exiting the optical waveguide and to generate a measure of the vital sign based at least in part on the received signal.

Abstract: A strain sensing device has a sub-assembly with at least one optical fiber therein, and a metallic coating encasing the sub-assembly. The metallic coating is strain coupled to the sub-assembly. A strain sensing system and a method of anticipating failure in a structure are provided. The strain sensing system and method of anticipating failure in a structure use the strain on the strain sensing device to calculate the strain on a structure of interest.

Abstract: A magnetic flux sensor is disclosed. The sensor comprises an optical fiber and at least one twin-grating structure formed on the optical fiber. Each twin-grating structure comprises a first optical grating structure, a second optical grating structure adjacent the first optical grating structure, and a sensing cavity disposed between the first and second optical grating structures. Each twin-grating structure is selectively responsive to a unique wavelength of light to generate an optical interference fringe signal. The sensor also includes a magnetostrictive coating disposed over each twin-grating structure to change an optical property of the twin-grating structure and a phase of the optical interference fringe signal when the magnetostrictive coating is exposed to changing magnetic flux.

Abstract: A telecommunications optical fiber is secured against intrusion by detecting manipulation of the optical fiber prior to an intrusion event. This can be used in a non-locating system where the detection end is opposite the transmit end or in a locating system which uses Fresnel reflections and Rayleigh backscattering to the transmit end to detect and then locate the motion. The Rayleigh backscattering time sliced data can be stored in a register until an intrusion event is detected. The detection is carried out by a polarization detection system which includes an optical splitter which is manufactured in simplified form for economic construction. This uses a non-calibrated splitter and less than all four of the Stokes parameters. It can use a polarimeter type function limited to linear and circular polarization or two linear polarizers at 90 degrees.

Abstract: In a method for the production of optical bands with several optical fibers, the surface of the optic fibers in said bands is treated such as to increase the optical damping in sections of the optic fibers. The generated damping may be reliably adjusted, whereby during (or after) the processing of the surfaces a measuring light is introduced into the fiber optic and the light output at the other end of the band is measured by means of a sensor such as a CCD camera. Possible production errors can thus be compensated for during the production process, for example, by an increased process time for the optic fiber. Optical sensor bands can be produced by the above method for application in the bumpers of motor vehicles as recognition sensors for the impact of a pedestrian. Other applications in which the bending of a sensor band is to be determined by optical means are also envisaged.

Abstract: In accordance with one aspect of the disclosed technology, wireless communications are used in a fiber surveillance system to enable monitoring of remote locations for vibrations, acoustic signals, stresses, stress fatigue or other detectable characteristics. A fiber that is deployed in the structure or region being monitored is connected a wireless transmitter that is used to transmit, to a receiving system, return optical signals obtained with the surveillance system. The return signals can be transmitted in raw form or after partial or total analysis.

Abstract: An optical system and method are disclosed. In an exemplary embodiment, the optical input system comprises a fiber optic cable defining an axial beam path, the fiber optic cable configured to reversibly deform at a bend location; an optical source coupled to the fiber optic cable and configured to inject an optic signal along the axial beam path; a detector coupled to the fiber optic cable and configured to receive a reflected signal from the fiber optic cable, the detector further configured to generate a distance parameter corresponding to the origin of the reflected signal; and a signal decoder configured to select a first input code from a plurality of input codes, the first input code corresponding to the distance parameter.

Abstract: The present disclosure provides an apparatus for sensing a motion. The apparatus comprises an optical fibre portion comprising a Bragg grating and an element for reducing an impact of an external force that is transversal to the Bragg grating. Further, the apparatus comprises a contact region arranged so that movement of a further region, that is in direct or indirect contact with the contact region and moves in a direction along a portion of the apparatus, causes movement of the optical fibre portion at the contact region. The apparatus also comprises a holder arranged for reducing movement of the optical fibre portion at a holding region when the optical fibre portion is moved at the contact surface. The apparatus is arranged so that movement of the contact region relative to the holding region causes a change in strain of the Bragg grating.

Abstract: A catheter for diagnosis or treatment of a vessel or organ is provided in which a flexible elongated body includes a tri-axial force sensor formed of a housing and a plurality of optical fibers associated with the housing that measure changes in the intensity of light reflected from the lateral surfaces of the housing resulting from deformation caused by forces applied to a distal extremity of the housing. A controller receives an output of the optical fibers and computes a multi-dimensional force vector corresponding to the contact force.

Abstract: A medical instrument system includes an elongate flexible instrument body with an optical fiber substantially encapsulated in a wall of the instrument body, the optical fiber including one or more fiber gratings. A detector is operatively coupled to the optical fiber and configured to detect respective light signals reflected by the one or more fiber gratings. A controller is operatively coupled to the detector, and configured to determine a twist of at least a portion of the instrument body based on detected reflected light signals. The instrument may be a guide catheter and may be robotically or manually controlled.

Abstract: A combined pressure and temperature sensor, the sensor comprising at least one first optical sensing element of a first type and at least one second optical sensing element of a second type, wherein the sensor is adapted to compensate for temperature and/or pressure effects in the first or second optical sensing element using a response of the other of the second or first optical sensing elements.

Abstract: An intruder detection system including a light emitting unit, a light guide, and a light receiving unit. The light emitting unit is arranged to emit light into the light guide and the light guide is arranged to guide the light to the light receiving unit. The impact of an intruder on the light guide causes changes in the characteristics of the light received at the light receiving unit.

Abstract: The present invention provides an apparatus for pressure sensing. The apparatus comprises a light guide, a Bragg grating incorporated into the light guide and a moveable wall portion. The moveable wall portion has opposite first and second sides and is being positioned so that a change in pressure at one of the sides relative to a pressure at the other side will move the moveable wall portion. The moveable wall portion is coupled to the Bragg grating so that the movement of the moveable wall portion causes a force on a side of the Bragg grating. The force has a component that is transversal to the Bragg grating and effects a change in strain of the Bragg grating and thereby a change in an optical period of the Bragg grating.

Abstract: The present invention relates to a system for sensing of a disturbance on an optical link. Data traffic from an optical source with a short coherence length is transmitted along the link to a receiver station on one or more of a plurality of time-division-multiplexed channels. One of the channels is used to transmit encoded phase information relating to the phase characteristics of the optical source output. At the receiver station, the actual phase characteristics of the arriving light from the optical source is compared with the encoded phase information. Since a physical disturbance of the link is likely to alter the actual phase characteristics of the arriving light but not the encoded phase information, it is possible to determine if a physical disturbance has occurred. The system can conveniently be used to monitor an optical link carrying communications traffic.

Abstract: A sensor arrangement using an optical fiber and methodologies for performing an analysis of a subterranean formation, such as a subterranean formation containing a hydrocarbon based fluid. The sensor arrangement may be used to measure one or more physical parameters, such as temperature and/or pressure, at a multiplicity of locations in the subterranean reservoir. The sensor arrangement may comprise a sensor array comprising an elongated outer casing for insertion in the subterranean formation and into a fluid in the subterranean formation. The sensor array may comprise an optical fiber defining an optical path that links one or more temperature sensors and one or more pressure sensors and transports measurement data generated by the temperature and pressure sensors. A data processing system may be connected to the sensor array to receive measurements from the sensor array and to compute one or more values of a property of an extraction installation operating on the subterranean formation.

Abstract: A patient monitoring system includes a plurality of diffraction gratings integrated along the length of an optical fiber, wherein the optical fiber and each grating are together configured to alter either the effective refractive index or grating periodicity of the respective grating at its corresponding location along the fiber in response to at least one desired external stimulus.

Abstract: The present disclosure provides an apparatus for sensing a motion. The apparatus comprises an optical fibre portion comprising a Bragg grating and an element for reducing an impact of an external force that is transversal to the Bragg grating. Further, the apparatus comprises a contact region arranged so that movement of a further region, that is in direct or indirect contact with the contact region and moves in a direction along a portion of the apparatus, causes movement of the optical fibre portion at the contact region. The apparatus also comprises a holder arranged for reducing movement of the optical fibre portion at a holding region when the optical fibre portion is moved at the contact surface. The apparatus is arranged so that movement of the contact region relative to the holding region causes a change in strain of the Bragg grating.

Abstract: A fault detection system for subsea pipeline DEH cable includes fiber optic element(s) (7) provided along the cable section concerned and located outside at least some of the cable insulation (2,3,4). The fiber optic element(s) are adapted to be influenced by fault inducing effects or damages to said cable section, so as to bring about an optical signal indicating a fault condition. The main feature of the invention is that said fiber optic element(s) (7) extend(s) inside a tubular, electrically conductive metal element (7a) adapted to melt down in the case of a fault current flowing therethrough as a result of damage to the cable insulation (2,3,4) at a point along said cable section.

Abstract: An optical sensor for detecting a substance includes a first waveguide and a second waveguide optically coupled via a directional coupler to the first waveguide. The sensor has a functional surface in a region of the directional coupler for accumulating or storing the substance to be detected so that an intensity of a coupling arranged by the directional coupler between the first waveguide and the second waveguide can be changed by the accumulating or storing of this substance. The first waveguide extends in a freely floating manner over a coupling path covered by the directional coupler or rests on a swellable material. The first waveguide is guided in a vicinity of the coupling path so that a spacing between the first waveguide and the second waveguide can be changed there by a deformation or movement of the first waveguide or of a carrier of the first waveguide.

Abstract: A tilt meter includes a housing structure defining an inner chamber sealed from an environment outside the housing structure. First and second optical fiber sections are provided in the inner chamber. The second optical fiber section is optically coupled to the first optical fiber section, with the second optical fiber section rotated azimuthally with respect to the first optical fiber section. The first and second optical fiber sections are arranged to receive light transmitted from a remote light source, and a tilt of the housing structure induces a differential pressure within the inner chamber to be detected by the first and second optical fiber sections.

Abstract: An apparatus for estimating at least one parameter includes: a deformable member configured to deform in response to the at least one parameter; a housing surrounding at least a portion of an external surface of the deformable member to define an isolated region around the portion and an isolated surface of the deformable member; and at least one optical fiber sensor disposed on the isolated surface and held in an operable relationship with the isolated surface, the at least one optical fiber sensor configured to generate a signal in response to a deformation of the deformable member.

Abstract: An optical coherence tomography system and method with integrated pressure measurement. In one embodiment the system includes an interferometer including: a wavelength swept laser; a source arm in communication with the wavelength swept laser; a reference arm in communication with a reference reflector; a first photodetector having a signal output; a detector arm in communication with the first photodetector, a probe interface; a sample arm in communication with a first optical connector of the probe interface; an acquisition and display system comprising: an A/D converter having a signal input in communication with the first photodetector signal output and a signal output; a processor system in communication with the A/D converter signal output; and a display in communication with the processor system; and a probe comprising a pressure sensor and configured for connection to the first optical connector of the probe interface, wherein the pressure transducer comprises an optical pressure transducer.

Abstract: A fiber grating sensor including an elastic circular plate and one or two FBG'ss attached to the bottom surface of the elastic circular plate. Two ends of the FBG are connected to an optic fiber for signal transmission. The fiber grating sensor readouts are independent of temperature variation. The fiber grating sensor mechanism according to the present invention may be applied in a variety of sensors such as gauge pressure transducer, differential pressure transducer, load cell and displacement transducer with a distributive design, and for various purposes.

Abstract: A system for use in a well includes an optical cable for positioning in the well. An optical sensor is optically coupled to the optical cable, where the optical sensor has a capillary tube and an optical fiber in the capillary tube. The capillary tube also includes a first sealed region containing a metallic material that is in liquid form at a downhole temperature in the well. A joint mechanism may attach the optical sensor to the optical cable.

Abstract: An embodiment of a sensor fiber includes: at least two fiber sections with a plurality of holes; and at least one other fiber section situated between said at least two fiber sections, wherein the at least one other fiber sections being without the plurality of holes.

Abstract: Acoustic monitoring of a conduit, a wellbore or a reservoir associated with hydrocarbon production or transportation and/or carbon dioxide sequestration is carried out using a fibre optic cable extending along or appurtenant to it as a distributed interferometer. Coherent Raleigh noise generated by the transmission of the coherent beam of radiation through the fiber optic is detected and processed to identify an acoustic occurrence.

Abstract: Calibration methods and apparatuses for a shape sensing optical fiber are disclosed. Strain is sensed in an optical fiber that is associated with a kinematic chain, and information derived from the sensed strain is used to determine a calibration relationship between the fiber and the kinematic chain. The strain may be sensed at a plurality of angles between two links in the kinematic chain. The strain may be sensed in a segment of the optical fiber that is associated with a joint in the kinematic chain as the joint sweeps through an arc. The strain may be sensed for the optical fiber in a known, predefined bend shape. The calibration information is stored in memory for later use during operation of the kinematic chain, so that shape information from the optical fiber can be used to accurately indicate the shape or pose of the kinematic chain.

Abstract: An apparatus for estimating a parameter at distributed locations, the apparatus including: an optical fiber having: a first series of fiber Bragg gratings (FBGs) and configured to measure the parameter at a portion of the distributed locations; a second series of FBGs and configured to measure the parameter at another portion of the distributed locations; and an optical interrogator configured to illuminate the optical fiber and to receive light signals resulting from the illumination, the light signals including first light signals from the first series of FBGs within a first range of wavelengths, second light signals from the second series of FBGs within a second range of wavelengths, and other light signals within a third range of wavelengths, the ranges of wavelengths being distinct from each other; wherein the first light signals and the second light signals are used to estimate the parameter at the distributed locations.

Abstract: An apparatus for estimating a shape, the apparatus including: an optical fiber configured to conform to the shape and having a first core offset from a centerline of the optical fiber, the first core having an optical characteristic configured to change due to a change in shape of the optical fiber wherein a change in the optical characteristic is used to estimate the shape. A method for estimating a shape is also disclosed.

Abstract: The present invention relates to devices which operate on gradient optical forces, in particular, nanoscale mechanical devices which are actuable by gradient optical forces. Such a device comprises a waveguide and a dielectric body, with at least a portion of the waveguide separated from the dielectric body at a distance which permits evanescent coupling of an optical mode within the waveguide to the dielectric body. This results in an optical force which acts on the waveguide and which can be exploited in a variety of devices on a nano scale, including all-optical switches, photonic transistors, tuneable couplers, optical attenuators and tuneable phase shifters. The waveguide can also comprise a gap such that two cantilever bridges are formed.

Abstract: In an FBG (Fiber Bragg Grating) sensor, a stress direction converter includes a flat portion to which stresses are applied from the exterior, and stress transmitting sections that are bridged from the flat portion to an optical fiber cable. An inclined portion of the optical fiber cable, through which reflected light reflected by gratings is transmitted, is disposed along an inclined section that makes up one of the stress transmitting sections.

Abstract: A system and method for monitoring the structural integrity of a structure is provided. An optical fiber is acoustically coupled to one or more of the structural elements. A source of optical energy is configured to inject optical energy into the optical fiber, and an optical detector is configured to detect a first optical return signal having characteristics that are affected by vibrations of the structural elements. An analyzer measures characteristics of the optical return signal to determine information concerning the movement of the structural elements monitored by the fiber optic cable. The results of the analyzer can be stored and so that the analysis of the optical return signal can be compared to previously recorded signals to determine changes in structural integrity over time. Multiple fibers can be acoustically coupled to the monitored structural elements to obtain additional data concerning the structural integrity.

Abstract: A compact, optically double-ended sensor probe with at least one 180° bend provided in the optical fiber in close proximity to a fiber Bragg grating temperature sensor suspends the optical fiber within a casing in such a way that the expansion and contract of the probe casing will not materially influence the temperature reading of the fiber Bragg grating by adding time varying or temperature varying stress components.

Abstract: A sensor for force is formed from an elastomeric cylinder having a region with apertures. The apertures have passageways formed between them, and an optical fiber is introduced into these passageways, where the optical fiber has a grating for measurement of tension positioned in the passageways between apertures. Optionally, a temperature measurement sensor is placed in or around the elastomer for temperature correction, and if required, a copper film may be deposited in the elastomer for reduced sensitivity to spot temperature variations in the elastomer near the sensors.

Abstract: An FBG (Fiber Bragg Grating) sensor is equipped with a plurality of stress detection sensors made up from optical fibers in which gratings that reflect light of a specified wavelength are arrayed, and a stress direction converter that converts stresses applied from the exterior into stresses of a direction in which the gratings are arrayed, and which transmits the stresses to each of the gratings. Consequently, the stress direction converter can transmit stresses, which are applied from a body, to a plurality of gratings.

Abstract: Localized strain is effectively eliminated in a shape sensing optical fiber where the fiber exits a link in a kinematic chain. In one aspect, the fiber is positioned in a channel within a fiber fixture portion of the link, and a surface of a lip of the channel is curved. The curved surface of the lip begins tangent to a wall of the channel and has a maximum radius of curvature that is less than the minimum bend radius that the fiber will experience during shape sensing. In another aspect, the fiber is positioned within a shape memory alloy tube that extends from the link.

Abstract: An extensometer having a loop of a single-mode optical fiber. At least two points of the loop are attached to desired locations on a specimen. Light is transmitted through the loop and the transmitted optical power is measured by a photodetector. The deformation of the specimen causes the size and shape of the loop to change, which changes the transmitted optical power. The change in optical power is related to extension or compression using calibration curves. The sensor works on the principle of transmitted power modulation through the curved section.

Abstract: A pressure sensor including: a deflectable diaphragm including a substantially central boss and channel; and, an optical waveguide having first and second arms, wherein the first arm is substantially aligned with an edge of the boss and the second arm is substantially aligned with an edge of the channel.

Abstract: An embodiment of the invention is a remote sensor that has an optical fiber terminating in a tip. A thin film porous particle having a characteristic optical response that changes in the presence of an analyte is optically coupled and physically attached to the tip of the optical fiber. The optical response of the particle changes in the presence of analyte, and the particle also serves to concentrate analyte. The thin film porous particle can be functionalized toward sensitivity for a predetermined analyte or analytes. A method of remote sensing exposes the remote sensor to an environment to be monitored for analyte. The thin film porous particle is probed with a beam of light. Reflected light is monitored through the optical fiber for a shift in frequency or intensity.

Abstract: At least one sensing region is formed on the bending sensor by providing a flexurally elastic base cover which is interrupted in at least one partial region of the sensing region or is structured using elevations and/or depressions. At least one planar optical fiber core is generated on the base cover. The optical fiber core has a greater index of refraction than the base cover. The optical fiber core is covered by a shroud. The optical fiber core has a greater index of refraction than the shroud.

Abstract: An optical device for monitoring a rotatable shaft is disclosed. The optical device has an optical waveguide arranged on the rotatable shaft and an optical sensor. The optical device further has a transmitting unit transmit the light signal, a transfer device to transmit the light signal between the transmitting unit and the optical waveguide and an evaluation unit for determining a physical variable from a light signal coming from the optical sensor and transferred by the transfer device, the evaluation unit being associated with the transmitting unit. The transfer device has an optical ‘multimode’ waveguide associated with a coupling device, the waveguide being associated with the transmitting unit and a further optical ‘multimode’ waveguide, with an associated coupling device associated with the optical waveguide and arranged on the rotatable shaft eccentrically to its axis.

Abstract: In accordance with one aspect of the present invention, a fiber surveillance system for monitoring a pipeline is provided. The surveillance system includes an optical fiber acoustically coupled to the pipeline to detect acoustic signals associated with vibrations or other activity near or from the pipeline. Optical energy is injected into the optical fiber and an optical detector receives an optical return-signal having certain characteristics resulting from vibrations impinging on the optical fiber. An analyzer is configured to determine operating information about the pipeline based on the optical return-signal. Two or more fibers can be acoustically coupled to the pipeline and arranged in varying configurations to yield greater resolution.

Abstract: Provided are a fluid conveying tube and a fluid leakage detecting system which can convey a cryogenic fluid such as LNG and which can quickly and reliably detect leakage of the fluid within the tube and the position of the leakage. An optical fiber 17 is continuously wound over the entire length of a flexible tube 1a. Leakage information detected by an optical fiber temperature sensor 21 is transmitted via a terminal 25a to an externally provided temperature measurement device. Meanwhile, when similar leakage occurs in the vicinity of a coupling section 3, the gas pressure inside the heat insulating layer 13a or the like increases due to the pressure of LNG within a corrugated tube 11 or a pressure generated as a result of evaporation of LNG. When the pressure inside the heat insulating layer 13a increases, information representing a change in the gas pressure is transmitted to a terminal 25b via a hollow pipe 27.

Abstract: A fiber-optic temperature sensor assembly comprises a cap with an inner cavity. A sensor member is received in the inner cavity of the cap. The sensor member has light-transmitting properties adapted to change with temperature variations. An optical fiber has a first end received in the inner cavity of the cap, and a second end of the optical fiber being adapted to be connected to a processing unit for transmitting light signals between the sensor member and the processing unit. A pressing device is received in the cap and pressing against the sensor member such that the sensor member is in operational contact with the first end of the optical fiber for transmission of light therebetween during operation of the fiber-optic temperature sensor assembly.

Abstract: A vibration monitoring system for an electrical submersible pump (ESP) that includes a fiber optic cable coupled with the ESP and an optical sensor coupled with the fiber optic cable. The optical sensor emits electromagnetic radiation into the fiber optic cable, some of which reflects back from optical discontinuities provided in the fiber optic cable. By receiving the reflected electromagnetic radiation, the optical sensor estimates the location of the optical discontinuities. Displacement and rate of displacement of the optical discontinuities can be estimated when the reflections are received over a period of time. Because the fiber optic cable, and the optical discontinuities, move with the ESP, displacement measurements of the optical discontinuities correlate to ESP movement, including ESP vibration.

Abstract: A measurement device including a fastener for use in attaching a first member to a second member, in which the fastener has an aperture extending through a length of the fastener, and a first optical fiber located within the aperture, in which the first optical fiber includes at least one fiber Bragg grating sensor. At least a portion of the first optical fiber can be secured within the aperture. A first end of the first optical fiber can be connected to an associated first optical connector and a second end of the first optical fiber can be connected to an associated second optical connector.