Abstract: A distributed fiber optic acoustic sensing system comprises an elongate body having an outer surface, an optical fiber disposed on the outer surface at a first predetermined wrap angle, and light transmitting and receiving means optically connected to the fiber for. The elongate body may include at least one substantially flat face, and/or a layer of swellable elastomer surrounding the body, and/or an outer elastomeric tube surrounding the elastomer layer. There may be at least one sensor pad disposed in the outer layer, the sensor pad comprising a stiffener and at least one longitudinal fiber affixed thereto or embedded therein. There may be a body of protective material surrounding the tube, which may have an outer surface that includes at least one substantially flat face and at least one sensor pad disposed in the body.

Abstract: An apparatus and method for measuring bending of an object, a position of an item touching the object, and a shearing force of the item using an optical waveguide may include a frequency measurer to measure a frequency of light reflected from a grating of an optical waveguide, and a bending measurer to determine bending of an object to which the optical waveguide is attached using the frequency.

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: 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 second Fiber Bragg Grating.

Abstract: A sensor comprising an optical fiber that includes a Bragg grating and a longitudinal-strain-inducing (LSI) jacket for inducing longitudinal strain into the optical fiber as a function of a transverse load, i.e., pressure or force. As the LSI jacket induces strain into the optical fiber, the fiber grating deforms, thereby changing the character of light reflected from the grating. The changes in character of the reflected light can be measured using suitable optical instrumentation. Additional physical characteristics that can be measured/sensed using an LSI-jacket-based sensor include moisture content/presence, chemical content/presence, and temperature. A transverse-load-sensing sensor can include transverse-load-applying structures that compress the LSI jacket under transverse load, causing the jacket to controllably elongate and thereby induce longitudinal strain into the optical fiber. Chemical and moisture LSI jackets can comprise materials that swell in the presence of the chemical or moisture.

Abstract: A fiber-optic sensor can have a Michelson sensor portion and a Mach-Zehnder sensor portion. A first splitter-coupler can be configured to split incoming light between a first fiber portion and a second fiber portion. A first polarization-phase conjugation device can be configured to conjugate a polarization phase of incident light corresponding to the first fiber portion, and a second polarization-phase conjugation device can be configured to conjugate a polarization phase of incident light corresponding to the second fiber portion. Each of the first and second polarization-phase conjugation devices can be configured to reflect light toward a detector and through the respective first and second fiber portions. A coupler can be configured to join light in the first fiber portion with light in the second fiber portion, and a third fiber portion can be configured to receive light from the coupler and to illuminate a second detector.

Abstract: An apparatus and method for determining an expanded diameter of a catheter balloon. An optical sensor includes an elongated optical fiber with at least one diffraction grating formed in a core of a distal portion thereof. The fiber distal portion is coupled to the inflatable balloon. Broadband light is transmitted to the diffraction grating by an optical interrogator. A portion of the light is reflected from the diffraction grating and is received by a wavelength detector. The wavelength of the reflected portion of light is dependent on the strain applied to the diffraction grating. The wavelength detector determines the strain in the balloon and correlates the strain to the diameter of the balloon.

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: An impact sensor of an active hood system includes a rear member, optical fiber sensors, a front member and membrane switch. Each of the optical fiber sensors is disposed on upper and lower portions of a front of the rear member and senses an impact force delivered from a bumper at the time of a crash with a pedestrian. The front member is disposed at the front of the rear member and has a protrusion part pressing the optical fiber sensors by the impact force delivered from the bumper at the time of the crash with the pedestrian. The membrane switch is disposed between the front member and the optical fiber sensor, divided into a plurality of regions from a left of the front member to a right thereof, and configured to sense a region which is pressed when the pedestrian crashes with the region.

Abstract: A bed monitoring device for monitoring bodily activity of a person and in particular vital signs such as respiration, cardiac activity and body's physical movement, including the presence, absence, step out or even falling out of a person using a sleeping environment such as a bed; mattress; top-mattress, bedding such as mattress covers, and pillow covers; a pad; a futon and the like. Based on the monitoring of bodily activity, it further allows determining sleep comfort and sleeping position of the user. It accordingly provides a valuable R&D tool to manufactures of sleeping articles like beds, mattresses, top-mattresses, futons and the like; but also in counseling consumers when buying sleeping articles under professional guidance. It comprises an optical fibre fixed to or mixed into a flat body positioned within said sleeping environment for detection of bodily activity by measuring a polarization variation of light propagating through the fibre.

Abstract: A method and corresponding apparatus for coupling an optical beam into a first end of an optical fiber includes two steps. First, light is coupled into a second end of the optical fiber such that an optical reference beam is output from the first end of the optical fiber. Second, at least one beam parameter of the optical beam is matched with the corresponding beam parameter of the optical reference beam. The second step may be performed using a wavefront sensor.

Abstract: An optical fiber (FD) that can be used for measuring pressure is arranged as follows. The optical fiber (FD) comprises a core (CO) and a cladding (CL) surrounding and contacting the core (CO). A stress-applying arrangement (SE1, SE2), which is embedded in the cladding (CL), applies constant anisotropic stress on the core (CO). This causes the core (CO) to exhibit a deformation. A pressure conversion arrangement (HO1, H02), which is also embedded in the cladding (CL), converts isotropic external pressure applied to the optical fiber (FD) into pressure-dependent anisotropic stress applied to the core (CO). The pressure conversion arrangement (HO1, H02) is disposed with respect to the stress-applying arrangement (SE1, SE2) so that the pressure-dependent anisotropic stress enhances the deformation of the core (CO) caused by the constant anisotropic stress.

Abstract: Disclosed is an endo-microscopic probe based on a non-resonant scanning method using an optical fiber which includes a housing configured to have a specific size, an optical fiber placed within the housing and configured to transfer a light source, a tubular piezoelectric element configured to surround the optical fiber within the housing, include a guide unit for guiding a movement of the optical fiber at the end of the tubular piezoelectric element, and provide a deformation value according to a deformation amount to the optical fiber through the guide unit using an external power source, and a lens unit placed within the tubular piezoelectric element, fixed to an end of the housing, and configured to transfer light output from an end of the optical fiber to a sample.

Abstract: A proximity sensor for detecting non-contact detection of a target using a fibre optic strain sensor and a system for operating multiple such proximity sensors is disclosed. The proximity sensor includes an optic fibre that has an optic fibre strain sensor that is coupled to a mass that moves in response to the target. The mass can be a magnet that moves when a ferrous target is within the magnetic field of the magnet causing the magnet to move and apply strain to the optic fibre strain sensor. The optic strain sensor can include periodic variation in the refractive index of the optic fibre, such as a fibre Bragg grating. The proximity sensor can include a second fibre optic sensor that is sensitive to temperature or a second fibre optic strain sensor coupled to a second magnet that operates in opposition to the first magnet. A system coupling multiple proximity sensors can include an interrogator that has an optical power source and a detector, each coupled to a processor.

Abstract: A display method and apparatus provides an easy to interpret presentation of multiple channel data, in the form of columns where the height of the column represents the relative measurement. A threshold line provides an indication of whether the measurement is above or below the threshold. Greater detail and numeric measurement values can be displayed for individual channels while the multiple channel display is in view.

Abstract: An instrument system that includes an elongate body and an optical fiber is provided. The elongate body has a longitudinal axis and capable of being twisted about the longitudinal axis. The optical fiber is operatively coupled with the elongate body and having a strain sensor provided thereon. The strain sensor is configured to indicate twist of the elongate body.

Abstract: A fiber optic acoustic sensing array. The fiber optic acoustic sensing array includes a core strength member and an optical fiber wound on the core strength member. The optical fiber includes a plurality of Fiber Bragg Gratings, and is coated with a voided plastic coating. An outer jacket covers the optical fiber coated with the voided plastic coating. Also disclosed are fiber optic sensing systems, methods of forming a fiber optic acoustic sensing array, and methods of operating fiber optic sensing systems.

Abstract: A method for measuring bending is provided. The method includes receiving a reflected signal from a strain sensor provided on an optical fiber; determining a spectral profile of the reflected signal; and determining bending of the optical fiber based on a comparison of the spectral profile of the reflected signal with a predetermined spectral profile.

Abstract: A method for measuring a physical parameter at a plurality of spaced locations in a subterranean formation using 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 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 second Fiber Bragg Grating.

Abstract: In certain variations, fiber shape sensing or measuring systems, devices and methods are described herein, which allow for measurement of three dimensional bending as well as twist measurements of various fibers, e.g., optical fibers and fiber optic probes of various sizes. In certain variations, the systems are designed to take advantage of unique light guiding properties of optical fibers and various fiber gratings.

Abstract: A system and method using both static and transient modeling of power cables coupled with real time measurements of distributed temperature profiles of both the cable and it's immediate environment to optimize the current loads of the power cable. The optical fibers used for measuring distributed temperature profiles can be integrated directly into the monitored power cables or be deployed alongside the power cables, including using the optical fibers deployed in optical power ground wire systems.

Abstract: A method and system for acoustic monitoring using a fiber optic cable. The optical fiber is used as a distributed interferometer that may be used to monitor activity, such as activity with respect to 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, production logging and/or the like.

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 optical system for pressure measurement has a pressure sensor element (4) with at least two parallel partially reflecting surfaces (5, 7), one of which is arranged on a diaphragm (6) movable with respect to another fixed said surface as a consequence of pressure differences across said diaphragm. Said surfaces are arranged so as to cause interference phenomena of light inciding substantially perpendicularly onto and reflected by the two surfaces depending upon the actual 10 distance between these surfaces. The pressure sensor element is made of material being stable at a continuous temperature up to at least 800° C. At least said diaphragm (6) of the sensor element is made of Si C, and at least a part (23) of the optical fiber (3) connecting to said sensor element is made of a material able to withstand a continuous temperature of at least 800° C.

Abstract: A fiber-optic sensor package (10) comprises a serial array of fiber-optic sensing coils (14, 16, 18, 20, 22) each of which is comprised in a respective fiber-optic sensor. Four (14, 16, 18, 22) of the coils are housed in a protective casing (24). One of the coils (22) is comprised in a fiber-optic electromagnetic field sensor. The other coils are comprised in respective fiber-optic geophones and/or hydrophones. A single package of the invention allows detection of both seismic and electromagnetic signals. An array of packages of the invention provides detection of both seismic and electromagnetic signal at a series of positions over a long distance or wide area, thus avoiding the need for two conventional arrays. A packages of the invention, and an array of such packages, require little or no electrical power input.

Abstract: An optical fiber may be constructed of a material having at least first and second constituents. The constituents and their relative abundance are selected such that the aggregate Brillouin frequency-shift response exhibited by a fiber constructed using the combined material is insensitive to a selected physical condition, such as temperature or strain, or the sensitivity is below an acceptable application-specific level, over an acceptable range of conditions. The constituents are selected such that the slopes or derivatives of the Brillouin frequency-shift response (with respect to the selected physical condition) of two of the constituents have opposite signs, and are combined in proper quantities such that the constituents balance each other to reduce the slope or derivative of the aggregate Brillouin frequency-shift response of the combined material to zero, or to an acceptable application-specific level, over an acceptable range of conditions.

Abstract: When a transverse force is applied to a stretched string that is fixed by its two ends, the string bends and the strain of the string increases to balance the transverse force. As a result, the axial force along the string can increase much more than the transverse force applied. By developing Fiber Bragg Grating (FBG) accelerometer based on transverse force rather than axial force, the force required for maintaining a high sensitivity is much smaller and thus the size of FBG accelerometers can be dramatically reduced. More importantly, FBG accelerometers based on transverse force have an inherent low cross-axial sensitivity. Simultaneous measurement of acceleration, temperature and displacement is realized by using two under-tensioned FBG. Displacement change is calculated by using the differential of the two FBG results.

Abstract: An apparatus for optical signal detection may include a housing in which a channel may be defined to receive an optical fiber in a bent configuration. The channel may have a predetermined radius of curvature to cause optical energy to escape from the fiber when an optical signal is being conveyed in the fiber and be detected at a photodetector arranged at the predetermined radius of curvature.

Abstract: A fiber-optic sensor for liquid-immersion detection includes an optical fiber and an interface material layer. The optical fiber has an angled physical contact (APC) surface. The interface material layer contacts with the APC surface. The interface material layer has a rough surface when in a dry state to produce a diffusion reflection. The interface material layer has a smooth surface to produce a specular reflection when the interface material layer absorbs a liquid in a wet state.

Abstract: The present disclosure provides an optical device comprising a first optical fiber portion having a first region and further regions between which the first region is positioned. The optical device also comprises a second optical fiber portion having a second region and further regions between which the second region is positioned. Further, the optical fiber comprises at least one member to which the first and second optical fiber portions are attached at the first and second regions. The first and second regions are positioned at opposite sides of an area defined between the first and second regions and spaced apart from each other by a first distance and wherein adjacent further regions are spaced apart by a second distance that is smaller than the first distance.

Abstract: The present invention provides systems, devices, and methods employing fiber optic shape and position tracking. The systems, devices, and methods permit measurement of and continuous tracking of the shape and position of objects whose shape dynamically changes with time. Applications include tracking and monitoring of endoscopes for diagnostic and surgical procedures.

Abstract: A monitoring device for monitoring a plurality of microactuators includes an optical fiber with a plurality of sensors, each sensor being placed close to a microactuator and having optical properties varying as a function of at least one environmental parameter, the monitoring device also including a polling device with at least one transmitter/receiver for a fiber optic network, and processing means capable of modulating the frequency of the optical signal transmitted by the transmitter to select the sensor close to a given microactuator, and of comparing the received optical signal with a template characteristic of the correct operation of the microactuator, and of generating a resultant signal, representative of the correct operation of the monitored microactuator. The invention has applications in the field of health monitoring of vehicles, notably of aircraft.

Abstract: A novel micro-optical electric field sensor exploits morphology-dependent shifts of the optical modes of dielectric cavities to measure temporally- and spatially-resolved of electric field with extremely high sensitivity. The measurement principle is based on the electrostriction effect on the optical modes of dielectric micro-resonators (or micro-cavities) and exploits recent developments in optical fiber and switching technologies. The optical modes are commonly referred to as “whispering gallery modes” (WGM) or “morphology dependent resonances” (MDR). By monitoring the WGM shifts, the electric field causing the electrostriction effect can be determined. Different sensitivities and measurement ranges (maximum measured electric field) can be obtained by using different cavity geometries (for example solid or hollow spheres), polymeric materials (PMMA, PDMS, etc) as well as poling the dielectric material.

Abstract: A fiber Bragg grating (FBG) based sensor is used as a strain sensing element to determine frame foot loading of a generator. Three FBGs may be used in tandem to form a basic Frame Foot Loading Module (FFL Module). Two modules are fixed on each vertical support gusset at the corner of the generator frame, with one module on the front of the gusset and a second module on the back of the gusset. Thus, each gusset may be instrumented with six FBG strain gauges or sensors. The gussets are chosen on each of the four corners of the generator. For two-pole generators the first three gussets at each corner may be used and, for four-pole generators the first four gussets may be used.

Abstract: An electrical line (5) for electrically conductively connecting two units arranged in a motor vehicle, where the units have insulated electrical conductors surrounded by a common electrically effective screen. Over the entire length of the line (5) the construction of the line includes at least one light conductor (10) which is connected in the operating position to an evaluating unit (12) coupled to a switching element (11), and is integrated in the screen (9) of the line (5), or is arranged directly underneath the screen (9) of the line (5) while being in contact with the line (5), so that damage to the line (5) leads with certainty at least to a deformation of the light conductor (10) which leads to a signal which can be recognized by the evaluating unit (12).

Abstract: A twisted, multicore fiber communicates light input to each core to an output. The twisting mitigates relative time delays of the input light traveling through each of the cores in the multicore fiber to the output caused by bending of that multicore fiber. An example application is in an optical network that includes an optical input terminal and an optical sensor connected by a twisted multicore connecting fiber. One example of twisted multicore optical fiber is helically-wrapped, multicore fiber.

Abstract: An instrument system that includes an elongate body, an optical fiber, and a detector is provided. The elongate body is capable of being twisted. The optical fiber includes a first portion coupled to the elongate body and a second portion having a curved shape adapted to reduce transfer of twisting or bending from the elongate body to the second portion, the second portion having a strain sensor provided thereon. The detector is coupled to the optical fiber and adapted to receive a signal from the strain sensor.

Abstract: An apparatus and method for testing composite structures in which ultrasonic waves are used to detect disbonds in the structures are described. The apparatus comprises a flexible structure carrying acousto-optical transducers such as fiber Bragg gratings. During use, the apparatus is mechanically and conformally coupled to the structure under test.

Abstract: The invention provides a method of obtaining the FBG data in final form (transforming the raw data into frequency and location data) by taking the raw FBG sensor data and dividing the data into a plurality of segments over time. By transforming the raw data into a plurality of smaller segments, processing time is significantly decreased. Also, by defining the segments over time, only one processing step is required. By employing this method, the refresh rate of FBG sensor systems can be improved from about 1 scan per second to over 20 scans per second.

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 fiber Bragg grating hydrophone includes a fluid chamber (1) and an optical fiber (2) in which a Bragg grating (3) is integrated, the optical fiber extending through the fluid chamber such that the Bragg grating is positioned inside the latter. The fluid chamber is filled with a compressible fluid and is defined by a rigid casing (4) including two end surfaces (28a, 28b) that are rigidly connected to the optical fiber. At least one of the two end surfaces of the rigid casing includes an opening (5a, 5b) closed by a deformable diaphragm (6a, 6b) that is rigidly connected to the optical fiber and that can be deformed in reaction to a difference in the pressures applied to the surfaces thereof, thereby modifying the length of the optical fiber as measured by a variation in the wavelength of a luminous flux extracted from the optical fiber.

Abstract: A method is provided for monitoring velocity of a fluid flow through a predetermined fluid flow space. A fiber optic conductor includes a flow measurement portion defining an elongated dimension extending across a portion of the fluid flow space. The fluid flow in the fluid flow space causes the measurement portion of the fiber optic conductor to flex in a direction transverse to the elongated dimension. Optical radiation is supplied to the fiber optic conductor, and optical radiation is received from the fiber optic conductor after the supplied optical radiation has passed through the measurement portion. The received optical radiation is analyzed to effect a determination of a flow velocity of the fluid flow.

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: An optical probe for emitting and/or receiving light within a body comprises an optical fiber that transmits and/or receives an optical signal, a silicon optical bench including a fiber groove running longitudinally that holds an optical fiber termination of the optical fiber and a reflecting surface that optically couples an endface of the optical fiber termination to a lateral side of the optical bench. The fiber groove is fabricated using silicon anisotropic etching techniques. Some examples use a housing around the optical bench that is fabricated using LIGA or other electroforming technology. A method for a forming lens structure is also described that comprises forming a refractive lens in a first layer of a composite wafer material, such as SOI (silicon on insulator) wafers and forming an optical port through a backside of the composite wafer material along an optical axis of the refractive lens. The refractive lens is preferably formed using grey-scale lithography and dry etching the first layer.

Abstract: The invention relates to an optical sensor arrangement comprising a measuring optical fiber demonstrating birefringence modifiable as a function of a measurement variable, and to an optical analysis unit having two optical branches implemented as optical fibers forming a Mach-Zehnder interferometer and an optical coupler for bringing together light guided in the two branches, wherein at least one output of the coupler is optically connected to at least one light-sensitive element, and wherein the analysis unit comprises a polarizing beam splitter from which the optical branches originate, wherein the measurement optical fiber is connected upstream of an optical input of the polarizing beam splitter, and wherein a polarization converter is disposed in a course of one of the optical branches. The invention further relates to a detection method that can be performed using said sensor arrangement.

Abstract: Methods and systems using one or more distributed feedback (DFB) lasers for capturing changes in the lasing environment are disclosed. Specifically, a sensor for measuring a measurand, such as pressure or temperature, or changes in a measurand, includes a fiber with at least one core, at least one fiber laser cavity formed by a single fiber grating in the core, wherein the laser operates on at least two modes along at least part of its length. The DFB laser includes a section that is bent into a non-linear shape and at least one pump laser connected to the fiber laser cavity. When the DFB laser experiences a perturbation or measurand change that changes the spacing of the modes, a change in an RF beat note is generated. This beat note can then be measured and related to the measurand change.

Abstract: An impact sensor of an active hood system includes a rear member, optical fiber sensors, a front member and membrane switch. Each of the optical fiber sensors is disposed on upper and lower portions of a front of the rear member and senses an impact force delivered from a bumper at the time of a crash with a pedestrian. The front member is disposed at the front of the rear member and has a protrusion part pressing the optical fiber sensors by the impact force delivered from the bumper at the time of the crash with the pedestrian. The membrane switch is disposed between the front member and the optical fiber sensor, divided into a plurality of regions from a left of the front member to a right thereof, and configured to sense a region which is pressed when the pedestrian crashes with the region.

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: An illumination apparatus having a radiation source and a light guide coupled thereto. The temperature of the light guide is monitored along its complete length. If a threshold temperature is exceeded, a switching mechanism will be triggered. The switching mechanism switches off the radiation source or triggers a warning signal.