Abstract: A method for measuring the deformation of a specimen using 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 fiber gas sensor including a core fiber comprising at least one Bragg grating region, a fiber cladding in contact with the core fiber along an entire length of the core fiber, and a sensing matrix structure disposed upon the outer surface of the fiber cladding along a portion of the length of the fiber cladding and surrounding the fiber Bragg grating region. The sensing matrix structure comprising a bonding layer disposed on the outer surface of the fiber cladding layer, a nano-structured trampoline matrix layer disposed on the outer surface of the bonding layer and a capping layer disposed on the outer surface of the matrix layer. The thermally modulated response amplitude of the fiber gas sensor is found to linearly depend upon the gas molecular weight, and can be directly used to determine heat specific capacity ratio of Cp/Cv.

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: The removal of material from the path of a high power laser beam during down hole laser operations including drilling of a borehole and removal of displaced laser effected borehole material from the borehole during laser operations. In particular, paths, dynamics and parameters of fluid flows for use in conjunction with a laser bottom hole assembly.

Abstract: An optical fiber cable for distributed fiber sensing of fluid pressure is disclosed. There are also disclosed a method and an apparatus for distributed fiber sensing of fluid pressure using the optical fiber cable. The optical fiber cable is adapted for distributed pressure sensing, and comprises: one or more optical fibers (120); and a buffer (130) surrounding the one or more optical fibers and adapted to deform asymmetrically under isotropic pressure (P) such that the fiber experiences asymmetric strain changing the birefringence of the one or more optical fibers. The optical fibers incorporated in the cable may be conventional single mode optical fibers. The optical fiber cable may be used to determine a pressure distribution along the length of the cable. The cable, apparatus or method may be used to detect pressures over long distances such as in pipes, pipelines, or wells.

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: Disclosed herein is a packing container including: a packing container body including a leading-out section which contains an optical probe having a first end section for incoming of a laser beam and a second end section for outgoing of the incoming laser beam, which leads out the first end section of the optical probe thus contained to the exterior and which is sealed, and a window section by which the laser beam going out from the second end section of the contained optical probe is led out to the exterior; and a light-transmitting member which closes the window section and permits the laser beam to pass therethrough.

Abstract: A shape sensing apparatus comprises an instrument including an elongated shaft with a neutral axis. The shape sensor also includes a first shape sensor with an elongated optical fiber extending within the elongated shaft at a first radial distance from the neutral axis. The apparatus also includes a shape sensor compensation device extending within the elongated shaft. The apparatus also comprises a tracking system for receiving shape data from the first shape sensor and compensating data from the shape sensor compensation device for use in calculating a bend measurement for the instrument.

Abstract: A temperature sensor that has an elongated sensing element having a length of at least 10 m, measured at a temperature of 20° C. The elongated sensing element includes an elongated jacket and an optical fiber mounted in the jacket and having an EFL of at least 0.35%, wherein the elongated sensing element has an average temperature error of less than 2° C.

Abstract: A long-distance fiber optic monitoring system having a sensing unit and an analyzer that is remotely located from the sensing unit is provided. The sensing unit comprises a source of optical energy for injecting optical energy into the fiber optical cable and an optical detector configured to detect an optical return signal from the optical fiber. The detected optical return signal is associated with an acoustic signal impinging on the optical fiber. The analyzer receives a signal from the remote sensing unit via the optical fiber that is representative of the optical return signal, and determines a location of a disturbance based at least on the received signal. The representative signal can be transmitted from the remote sensing unit to the analyzer as an optical signal or via a metallic wired included with the optical fiber.

Abstract: This disclosure is of a fiber optic switch, where an actuated plunger causes a snap-action mechanism to change rapidly from a first state to a second state and place a loaded member from a first strain condition into a second strain condition where the two conditions are substantially different. A strain sensor mounted on the loaded member senses the strain of the loaded member and transmits a corresponding signal on a fiber optic cable.

Abstract: This application describes methods and apparatus for distributed acoustic sensing providing enhanced sensitivity for certain acoustic signals. The method uses a fibre optic distributed acoustic sensing (DAS) apparatus (106) to detect acoustic signals wherein the fibre optic distributed acoustic sensor comprises at least one optical fibre (104) deployed in an area of interest (204) such that at least one section of said optical fibre is deployed to monitor the acoustic response of a cavity (206) to incident acoustic signals. The cavity is dimensioned such that the cavity resonates at a desired frequency and thus the relevant sensing portions of the DAS sensor show an enhanced response to acoustic signals which excite resonance in the cavity. The optical fibre (104) may be deployed to run through said cavity.

Abstract: A side-hole optical cane for measuring pressure and/or temperature is disclosed. The side-hole cane has a light guiding core containing a sensor and a cladding containing symmetrical side-holes extending substantially parallel to the core. The side-holes cause an asymmetric stress across the core of the sensor creating a birefringent sensor. The sensor, preferably a Bragg grating, reflects a first and second wavelength each associated with orthogonal polarization vectors, wherein the degree of separation between the two is proportional to the pressure exerted on the core. The side-hole cane structure self-compensates and is insensitive to temperature variations when used as a pressure sensor, because temperature induces an equal shift in both the first and second wavelengths. Furthermore, the magnitude of these shifts can be monitored to deduce temperature, hence providing the side-hole cane additional temperature sensing capability that is unaffected by pressure.

Abstract: A method for determining the physical location of a fiber optic channel in a fiber optic cable comprises the steps of a) providing at least one location key having a known physical location, b) establishing the location of the location key with respect to the fiber optic channel, and c) using the location information established in step b) to determine the physical location of the channel. The location key may comprises an acoustic source, a section of fiber optic cable that is acoustically masked, or at least one magnetic field source and step b) comprises using a Lorentz force to establish the location of the magnetic field source with respect to the fiber optic channel.

Abstract: The invention relates to an optic-based sensing assembly and a system incorporating the assembly and related use of the assembly. In particular, the invention relates to an optic-based catheter assembly and related system used to determine contact between a catheter and surrounding proximate environment, such as tissue. An embodiment of such a system may, for example, be used for visualization, mapping, ablation, or other methods of diagnosis and treatment of tissue and/or surrounding areas.

Abstract: In one embodiment, a force sensor apparatus is provided including a tube portion having a plurality of radial ribs and at least one fiber optic strain gauge positioned over each rib of the plurality of radial ribs. The strain gauges are comprised of a negative thermo-optic coefficient optical fiber material in one embodiment. A proximal end of the tube portion is operably couplable to a shaft of a surgical instrument that is operably couplable to a manipulator arm of a robotic surgical system, and a distal end of the tube portion is proximally couplable to a wrist joint coupled to an end effector. In another embodiment, adjacent fiber optic strain gauges with differing thermal responses are used to solve simultaneous equations in strain and temperature to derive strain while rejecting thermal effects. In yet another embodiment, a thermal shunt shell is over an outer surface of the tube portion. An advantageous surgical instrument having improved temperature compensation is also provided.

Abstract: Methods of manufacturing optical devices are disclosed. The method includes providing a structure-forming fiber bonded to at least one other optical component, the structure-forming fiber having a preferentially-etchable portion including at least one radial etching boundary and at least one axial etching boundary, and etching the preferentially-etchable portion to the radial and axial etching boundaries to produce a precise optical structure. The preferentially-etchable portion may be removed through one or more radial openings in the structure-forming fiber. Numerous other aspects are provided.

Abstract: A surface layer formed of a composite material is stacked on the surface of a core layer formed of a foam synthetic resin material, and an arrester portion is provided in an interface region between the surface layer and the core layer to prevent the progression of delamination between the surface layer and the core layer. Optical fibers with grating portions are embedded inside the arrester and along the surface layer, and the spectra of reflected light from the optical fibers are compared to detect the occurrence position of a crack between the surface layer and the core layer.

Abstract: A Fabry-Perot optical sensor for sensing a parameter such as pressure or the like is provided. The sensor includes a lead optical fiber from the end of which projects a spacer having an end surface curving inwardly. A diaphragm extends across the forward end of the spacer. The diaphragm is flexible in response to the parameter to be measured and defines a forward reflector of the Fabry-Perot cavity within the optical sensor. A method for manufacturing such a sensor is also provided.

Abstract: A fiber-optic vibration sensor for generators in power stations is disclosed. The sensor includes an optical fiber which has a freestanding end, wherein the freestanding end is caused to oscillate under the influence of vibrations, and the resulting oscillations are detected as a measure for the vibrations. Only the net weight of the optical fiber serves as a centrifugal mass.

Abstract: A fiber optic splice housing and integral dry mate connector system. In a described embodiment, a fiber optic connection system includes optical fiber sections in respective conduit sections. Each of the conduit sections is received in the housing assembly. An optical connection between the optical fiber sections is positioned within the housing assembly.

Abstract: The present invention relates to a sensor using a tilted fiber grating to detect physical manifestations occurring in a medium. Such physical manifestations induce measurable changes in the optical property of the tilted fiber grating. The sensor comprises a sensing surface which is to be exposed to the medium, an optical pathway and a tilted grating in the optical pathway. The grating is responsive to electromagnetic radiation propagating in the optical pathway to generate a response conveying information on the physical manifestation.

Abstract: A fiber optic splice housing and integral dry mate connector system. In a described embodiment, a fiber optic connection system includes optical fiber sections in respective conduit sections. Each of the conduit sections is received in the housing assembly. An optical connection between the optical fiber sections is positioned within the housing assembly.

Abstract: A fiber-inline MZI device for temperature sensing or refractive index (RI) sensing, the device comprising: a section of a Photonic Crystal Fiber (PCF) having at least two air holes infiltrated with a liquid analyte to form a waveguide channel, the liquid analyte forming rods in the PCF; wherein the rods leave an interference fringe pattern in the transmission spectrum when light is injected into the PCF, and fringe dips are tracked over a wide wavelength range in order to sense the temperature or refractive index.

Abstract: An acoustic-wave sensor (10) is constructed by a membrane (11) adapted to be displaced by an acoustic wave, a first waveguide (16a) for transmitting light therein, an optical coupling part (15) to which the light transmitted through the first waveguide (16a) is adapted to be optically coupled, and a second waveguide (16b) through which the light coupled from the optical coupling part (15) transmits. When the membrane (11) is displaced by its reception of the acoustic wave, at least one of an optical coupling coefficient between the first waveguide (16a) and the optical resonator (15) and an optical coupling coefficient between the second waveguide (16b) and the optical resonator (15) is changed to output a corresponding optical signal.

Abstract: According to some embodiments, the optical fiber comprises: (i) a core having a first index of refraction n1; (ii) a cladding surrounding the core and having a second index of refraction n2, such that n1>n2, wherein cladding has at two sets of stress rods extending longitudinally through the length of the optical fiber, wherein the two sets of stress rods have CTE coefficients and/or softening points different from one another and different from that of cladding.

Abstract: A mechanical stress activated interface and system comprising piezo-optical elements is described. The piezo-optical elements are fabricated from waveguides each having a core surrounded by a cladding material. The waveguides are supported on a substrate, thereby forming a thin sheet. The interface may take advantage of ambient light for illumination. Activation of the cores, such as by a user pressing the interface, may result in changes to their indices of refraction. More ambient light will be conducted along the lengths of the cores under stressed conditions than under non-stressed conditions. The output at the ends of the piezo-optical elements may be detected by light receiving elements. The output of the light receiving elements may be used by electronics coupled to a computer to determine which waveguides have been stressed, thereby determining the location of the touch on the interface. Methods for fabricating and using the interface are also described.

Abstract: A medical instrument system includes an elongate instrument body defining a longitudinal axis and capable of being twisted about its longitudinal axis and an optical fiber sensor coupled to the instrument body. A detector is operatively coupled to the optical fiber sensor and configured to detect respective light signals transmitted on the optical fiber sensor. A controller is operatively coupled to the detector and configured to determine a twist of a portion of the instrument body about its longitudinal axis based on an analysis of detected light signals.

Abstract: A fiber optic splice housing and integral dry mate connector system. In a described embodiment, a fiber optic connection system includes optical fiber sections in respective conduit sections. Each of the conduit sections is received in the housing assembly. An optical connection between the optical fiber sections is positioned within the housing assembly.

Abstract: The present invention provides an apparatus for distributed pressure sensing. The apparatus comprises a series of Bragg gratings, a light guide incorporating the series of Bragg gratings and a plurality of moveable wall portions. The moveable wall portions are coupled to respective Bragg gratings so that the movement of one of the moveable wall portion causes a force on the respective Bragg grating resulting in a change in strain of the respective Bragg grating. The apparatus also comprises at least one rigid member that is attached at attachment regions between which a sensing region of at least one Bragg grating is defined. The rigid member is arranged so that a strain in the sensing region is not directly influenced by a change in strain of the light guide outside the sensing region.

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: A device having two sets of raised portions inside a metal case is provided for bending an optic fiber. According to some embodiments, the two sets of raised portions are on two plates that are biased apart by a spring means. According to some embodiments, the metal case prevents viewing of an optic fiber in the metal case. According to some embodiments, an adjustable stopping element is provided to limit movement of the two plates toward each other.

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 rotor blade monitoring system for use with a wind turbine. The wind turbine includes at least one rotor blade. The rotor blade includes a sidewall that extends between a root portion and a tip portion. The rotor blade monitoring system includes a fiber optic strand that is coupled to the rotor blade sidewall. The fiber optic strand has a length that extends from the root portion towards the tip portion. A plurality of sensors are coupled to the fiber optic strand. Each sensor of the plurality of sensors is axially spaced along the fiber optic strand and is configured to transmit a signal indicative of a position of a respective portion of the rotor blade.

Abstract: It is an objective of the present invention to provide a highly sensitive optical pressure sensor that uses a Mach-Zehnder Interferometer to measure pressure. The pressure sensor comprises a deflectable diaphragm including a substantially central boss and channel and an optical waveguide having a first arm and a second arm, 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, and further wherein the first and second arms contain a periodic array of etched holes to improve the overall sensitivity of the pressure sensor. The pressure sensor further comprises a light source coupled to the optical waveguide for introducing light to the waveguide and a light detector coupled to the waveguide for detecting changes in the intensity of light. The change in light intensity is then correlated to an applied pressure.

Abstract: A method of measuring fiber twist in a multi-core optical fiber bearing an FBG with polarization dependent reflectivity. The state of polarization of the launched light is adjusted until the reflected FBG wavelength is maximal, indicating that light reaching the FBG is linearly polarized, and the polarization axis of the light reaching the FBG is aligned with the slow birefringent axis of the FBG; the SOP of launched light is now measured. Bending experienced by the fiber is measured conventionally, and birefringence produced by bending of the multi-core optical fiber is calculated. A candidate amount of twist between the launch location and the FBG is proposed, and the corresponding twist-induced birefringence is calculated. When calculations show that light with the launched SOP becomes linearly polarized and aligned with the FBG after traversing a fiber section with the calculated birefringences and proposed rotation, the amount of twist has been properly identified.

Abstract: A security system lays out a sensing optical fiber tautly at the perimeter of an area to be secured. The sensing optical fiber has at least one sensing Fiber Bragg Grating (FBG) which is stretched when the sensing optical fiber is stretched by an intruder. The center wavelength of reflection of the stretched sensing FBG shifts towards longer wavelengths. The shifted center wavelength of reflection is detected using a reference FBG with a longer center wavelength of reflection. The sensing optical fiber has a loose buffer coating for isolating the sensing optical fiber and the sensing FBG from nuisance disturbances and noise such as vibrations caused by wind. Trip wires may be attached to the sensing optical fiber for enhancing intruder detection. A cut of the sensing optical fiber may be detected by monitoring the optical power exiting the far end of the sensing optical fiber.

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 bridge intelligent cable system with a built-in fiber grating sensor is provided, which is applied in a cable bearing structure such as a cable-stayed bridge, a suspension bridge, and an arch bridge. The system includes an anchor cup, a wire dividing plate, a connecting cylinder, a fiber grating sensor, and a cable body, in which the fiber grating sensor includes a fiber grating strain sensor and a fiber grating temperature sensor, tail fibers of the fiber grating strain sensor and the fiber grating temperature sensor are led out, the packaged fiber grating strain sensor is fixedly connected to an outer-layer steel wire of the connecting cylinder, the packaged fiber grating temperature sensor is suspended on the steel wire of the connecting cylinder, holes are punched in the wire dividing plate, and a preserved steel pipe is buried in advance in the connecting cylinder and the anchor cup.

Abstract: A method, apparatus and system for determine a parameter of a structure is disclosed. A fiber optic cable is coupled to a member. The fiber optic cable includes at least a first core helically arranged in the fiber optic cable that includes at least a first sensor and a second sensor. A first measurement related to the parameter is obtained at the first sensor, and a second measurement at the second sensor related to the parameter is obtained at the second sensor. A difference between the first and second measurements is used to determine the parameter.

Abstract: The invention relates to an optical strain gauge using a glass fiber (1) comprising a Bragg grating (2). The glass fiber is coated with a sheath (3) of polyether ether ketone with an admixture of at least 10 weight percent and a maximum of 40 weight percent of an inorganic filler, with a particle size of between 0.08 ?m and 12 ?m. The outer diameter of the sheath (3) is between 0.2 mm and 1.2 mm. The ratio D/d between the outer diameter D of the sheath (3) and the diameter d of the glass fiber (1) is between 2 and 6. A pressure of the sheath (3) on the glass fiber (1) is such that essentially no relative movement can occur between the glass fiber (1) and the sheath (3).

Abstract: A detector (50) including a sensor (52) configured to detect entry of a portion of a wheel (20) into a portion of a clearance gap (37) and thereby to signify that the wheel (20) has deviated from the intended wheel path.

Abstract: A system for making temperature and pressure measurements distributed over a distance comprises a plurality of Bragg grating measurement points disposed in an optical fiber with a predetermined spacing between adjacent Bragg grating measurement points and a substrate with the optical fiber disposed thereon, at least a portion of the optical fiber being wrapped around the substrate with at least one predetermined wrap angle, wherein the predetermined wrap angle and predetermined spacing are selected to enable a temperature measurement signal to be distinguished from a bending measurement signal, wherein the substrate has a first coefficient of thermal expansion greater than a second coefficient of thermal expansion of the optical fiber and wherein the substrate comprises a hollow tube portion and a solid rod portion, each having optical fiber disposed thereon.

Abstract: A sensor is disclosed herein. The sensor includes a fiber operable to communicate a light wave. The sensor also includes at least first and second Fiber Bragg Gratings disposed along the fiber. The sensor also includes a structure operable to be deformed in a plane of deformation. The at least first and second Fiber Bragg Gratings are disposed on opposite sides of the structure in the plane of deformation. The sensor also includes an interrogation unit operable to receive first and second signals corresponding to first and second wavelengths from the at least first and second Fiber Bragg Gratings. The first signal is associated with the first Fiber Bragg Grating and the second signal is associated with the first Fiber Bragg Grating. The sensor also includes a processor operably to derive a difference between the wavelengths of the first and second signals and compare the difference with data correlating wavelength differences to extents of deformation of the structure to yield a current extent of deformation.

Abstract: An optical fiber sensing apparatus includes: a substrate configured to deform in response to an environmental parameter; an optical fiber sensor including a core having at least one measurement location disposed therein and a protective coating surrounding the optical fiber sensor, the protective coating made from a polyimide material; and an adhesive configured to adhere the optical fiber sensor to the substrate, the adhesive made from the polyimide material.

Abstract: A method and system for designing a patient-specific orthopaedic surgical instrument includes coupling a knee sleeve to a leg of the patient. The knee sleeve includes sensors configured to generate sensor data indicate of the position of the respective sensor. The method also include determining angulation data indicative of the angulation of the knee based on the sensor data. The angulation data may be indicative of, for example, the ligament laxity of the knee. The method may also include generating a medical image(s) of the knee. The design of the patient-specific orthopaedic surgical instrument is determined based on the angulation data and the medical image(s).

Abstract: An integrated transducer device includes an optical transducer and an acoustic transducer integrally joined with the optical transducer. The acoustic transducer includes a membrane responsive to acoustic signals, the membrane being aligned with the optical transducer such that optical signals emitted or received by the optical transducer pass through the membrane. A propagation direction of the acoustic signals emitted or received by the acoustic transducer is collinear with a propagation direction of the optical signals emitted or received by the optical transducer.

Abstract: Acoustic monitoring is carried out using a fiber optic cable. Coherent Rayleigh noise generated by the transmission of a coherent beam of radiation through the fiber optic cable is detected, a phase of the coherent Rayleigh noise is measured and the measured phase is processed to identify an acoustic occurrence along the fiber optic cable. In certain aspects, an optical fiber serves as a distributed interferometer that may be used to monitor a conduit, wellbore or reservoir. The distributed interferometric monitoring provides for accurate detection of acoustic occurrences along the fiber optic cable and these acoustic occurrences may include fluid flow in a pipeline or wellbore, processes taking place in a wellbore or pipeline, fracturing, gravel packing, or production logging.

Abstract: Systems and methods for sensing properties of a workpiece and embedding a photonic sensor in metal are disclosed herein. In some embodiments, systems for sensing properties of a workpiece include an optical input, a photonic device, an optical detector, and a digital processing device. The optical input provides an optical signal at an output of the optical input. The photonic device is coupled to the workpiece and to the output of the optical input. The photonic device generates an output signal in response to the optical signal, wherein at least one of an intensity of the output signal and a wavelength of the output signal depends on at least one of thermal characteristics and mechanical characteristics of the workpiece. The optical detector receives the output signal from the photonic device and is configured to generate a corresponding electronic signal.

Abstract: A long-distance fiber optic monitoring system having a sensing unit and an analyzer that is remotely located from the sensing unit is provided. The sensing unit comprises a source of optical energy for injecting optical energy into the fiber optical cable and an optical detector configured to detect an optical return signal from the optical fiber. The detected optical return signal is associated with an acoustic signal impinging on the optical fiber. The analyzer receives a signal from the remote sensing unit via the optical fiber that is representative of the optical return signal, and determines a location of a disturbance based at least on the received signal. The representative signal can be transmitted from the remote sensing unit to the analyzer as an optical signal or via a metallic wired included with the optical fiber.