3610results about "Force measurement by measuring optical property variation" patented technology

The central system component of the present invention is a flexible “smart cable” which enables accurate measurement of local curvature and torsion along its length. These quantities are then used to infer the position and attitude of one end of the cable relative to the other. Sufficiently accurate measurements of the local curvature and torsion along the cable allow reconstruction of the entire cable shape, including the relative position and orientation of the end points. The smart cable for making these measurements comprises a multicore optical fiber, with individual fiber cores constructed to operate in the single mode regime, but positioned close enough to cause cross-talk (mode coupling) between cores over the length of the fiber. This cross-talk is very sensitive to the distribution of strains (curvature and torsion) along the cable.

Apparatus is provided for diagnosing or treating an organ or vessel, wherein a deformable body having at least two optical fiber sensors disposed in a distal extremity thereof is coupled to processing logic programmed to compute a multi-dimensional force vector responsive to detected changes in the optical characteristics of the optical fiber sensors arising from deflection of the distal extremity resulting from contact with the tissue of the wall of the organ or vessel. The force vector may be used to facilitate manipulation of the deformable body either directly or automatically using a robotic system.

Systems and methods for measuring the stress profile of ion-exchanged glass are disclosed, based on the TM and TE guided mode spectra of the optical waveguide formed in the ion-exchanged glass. The method includes digitally defining from the TM and TE guided mode spectra positions of intensity extrema, and calculating respective TM and TE effective refractive indices from these positions. The method also includes calculating TM and TE refractive index profiles nTM(z) and nTE(z) using either an inverse WKB calculation or a fitting process that employs assumed functions for nTM(z) and nTE(z). The method also includes calculating the stress profile S(z)=[nTM(z)−nTE(z)] / SOC, where SOC is a stress optic coefficient for the glass substrate. Systems for performing the method are also disclosed.

In one exemplary embodiment of the present invention, method and system can be provided for obtaining information associated with at least one portion of a sample. For example, a temperature change can be caused in the portion of the sample. At least one first electro-magnetic radiation can be forwarded to a section near or in the portion of the sample. A deformation of the section can be identified at a plurality of depths as a function of (i) a phase of at least one second electro-magnetic radiation provided from the section, and / or (ii) a rate of change of the phase and / or an amplitude of the second electro-magnetic radiation. In another exemplary embodiment of the present invention, method and system can be provided for controlling a temperature distribution in a sample. For example, an electro-magnetic radiation can be provided to the section in the sample at a particular wavelength. The temperature distribution can be controlled by modifying the particular wavelength of the electro-magnetic radiation when the electro-magnetic radiation is provided to the section.

A fiber optic force sensing assembly for detecting forces imparted at a distal end of a catheter assembly. The structural member may include segments adjacent each other in a serial arrangement, with gaps located between adjacent segments that are bridged by flexures. Fiber optics are coupled to the structural member. In one embodiment, each fiber optic has a distal end disposed adjacent one of the gaps and oriented for emission of light onto and for collection of light reflected from a segment adjacent the gap. The optical fibers cooperate with the deformable structure to provide a change in the intensity of the reflected light, or alternatively to provide a variable gap interferometer for sensing deformation of the structural member. In another embodiment, the gaps are bridged by fiber Bragg gratings that reflect light back through the fiber optic at central wavelengths that vary with the strain imposed on the grating.

The present invention concerns movement facilitation devices for facilitating movement between a first portion of a first object and a second portion of the first object. One or more of the movement facilitation devices may be combined to form a movement device for facilitating movement of at least one joint or limb of a patient's body. One form of a movement device according to the invention is a glove which at least partially encloses the joint or limb. The invention also encompasses systems for applying Continuous Passive Motion therapy to a joint or limb of a patient using the devices of the invention. The invention also encompasses the use of shape memory materials and of conducting polymers in the devices and systems of the invention, as well as the design of force transducers and actuators that may be used in the devices.

A multi-force sensing instrument includes a tool that has a tool shaft having a distal end and a proximal end, a strain sensor arranged at a first position along the tool shaft, at least one of a second strain sensor or a torque-force sensor arranged at a second position along the tool shaft, the second position being more towards the proximal end of the tool shaft than the first position, and a signal processor configured to communicate with the strain sensor and the at least one of the second strain sensor or the torque-force sensor to receive detection signals therefrom. The signal processor is configured to process the signals to determine a magnitude and position of a lateral component of a force applied to the tool shaft when the position of the applied force is between the first and second positions.

A system such as for sensing strain or temperature of an aircraft and for transmitting information in communication systems. A sensor array includes a first light responsive Bragg grating sensor having a first operating bandwidth and a second light responsive Bragg grating sensor having a second operating bandwidth. Each sensor modifies light provided to it at a wavelength indicative of changes in strain or temperature. The second sensor operates within a bandwidth which is different from the operating bandwidth of the first sensor. A tunable light source such as an LED and tunable etalon provides light for illuminating the first and second sensors, the provided light having a wavelength which varies within a band including the first and second bandwidths. A detecting circuit provides signals representative of light modified by the first and second sensors. A processor processes the representative signals to determine the strain and / or temperature.

A tactile sensor includes a photosensing structure, a volume of elastomer capable of transmitting an image, and a reflective skin covering the volume of elastomer. The reflective skin is illuminated through the volume of elastomer by one or more light sources, and has particles that reflect light incident on the reflective skin from within the volume of elastomer. The reflective skin is geometrically altered in response to pressure applied by an entity touching the reflective skin, the geometrical alteration causing localized changes in the surface normal of the skin and associated localized changes in the amount of light reflected from the reflective skin in the direction of the photosensing structure. The photosensing structure receives a portion of the reflected light in the form of an image, the image indicating one or more features of the entity producing the pressure.

The invention discloses a device for monitoring the state of a power transmission line tower-line system, which fully utilizes the advantages of corrosion resistance, wide operation temperature range, anti-electromagnetic interference, passivity, long measuring distance, reliable operation and long service life and the like of optical fiber sensors to configure the optical fiber sensors on a transmission conductor and a tower in a quasi-distributed structure for detecting the temperature, the strain and the acceleration of the transmission conductor and the multipoint stress variation on the tower which are transmitted to an optical modulator demodulator for demodulating and are sent to a computer analyzing and processing system for calculating to obtain the icing quality, the waving amplitude, the breeze vibration amplitude and frequency and the sag of the transmission conductor, and the inclination angle of the tower, thus realizing the simultaneous monitoring on the icing, the waving, the breeze vibration and the sag of the transmission conductor, and the inclination angle state of the tower, and being capable of finishing long-time reliable operation under the on-site severe environment conditions.

The invention relates to an instrumented tubular device for transporting a pressurized fluid notably in the field of oil exploration and in that of the transport of gas or hydrocarbons. This device comprises a tube (20) in which this fluid flows, with which are associated means for measuring the main deformations of this tube, and means for measuring the temperature of the fluid in the tube. This tube is equipped with measurement means integral with its surface and offset by at least one remote optical cable towards an electronic measurement system. These measurement means are means for assembling at least two non-parallel optical fibers which comprise at least three assemblies (B1, B2, B3) of at least two optical gages with Bragg gratings attached to at least three measurement locations (22) and connected to the remote optical cable (23) via optical fibers. At least one assembly further comprises a temperature gage.

The invention relates to a system for distributed or dispersed measurement of axial and bending deformations of a structure including at least one threadlike device (10) equipped for the distributed or dispersed measurement of these axial and bending deformations, and means for processing measurement signals generated by said device, in which each device includes a cylindrical reinforcement (11) supporting, at its periphery, at least three optical fibres (12) locally parallel to the axis of the reinforcement, and in which the processing means implement means for spectral or time division multiplexing of signals coming from optical fibres.

A fiber optic acoustic sensor system including an optical conductor having low reflectivity mirrors is provided. Optical sensors are provided by sections of the optical conductor bounded by pairs of the low reflectivity mirrors. Pulses of light are injected into the optical conductor and reflected by the low reflectivity mirrors. The reflected pulses of light are processed using a compensating interferometer to generate interference patterns representative of the environmental conditions acting upon the optical conductor.

A technique facilitates the monitoring of elongate structures. An elongate structure is combined with an optical fiber deployed along the structure. An interrogation system is operatively joined with the optical fiber to input and monitor optical signals to determine any changes in parameters related to the structure.

A distributed fiber sensor based on spontaneous Brillouin scattering uses a single-frequency fiber laser as a source and a cw Brillouin fiber ring laser as an OLO to optically shift the frequency of the OLO to set the Brillouin / OLO beat frequency within the bandwidth of a conventional heterodyne receiver. The distributed fiber sensor is capable of real-time measurement of both temperature and strain.

An optical displacement sensor is disclosed that provides a optical displacement sensor that includes a optically-resonant cavity tuned to an operating wavelength without some of the disadvantages for doing so in the prior art. An embodiment of the present invention tunes an operating wavelength used with a Fabry-Perot interferometer to develop a desired relationship between the wavelength and the Fabry-Perot interferometer's initial cavity length.

The invention was originally developed to determine the strain-relief capability of a fusion splice protector as well as the compressive stress imparted to a fusion splice by the splice protector. The invention also permits performance and comparative analyses of splice protectors as well as any package in which the optical fiber is at least partially disposed. To those ends a fiber Bragg grating (FBG) is axially arranged relative to the package such that a free or reference section of the FBG protrudes from the package while a shielded section lies within the package. Broadband light is supplied to the FBG which reflects certain wavelengths that are measured by an optical spectrum analyzer. The FBG reflected spectra will be split into two peaks as the reference and shielded sections experience different amounts or types of stress thereby providing a powerful analysis tool. A wavelength shift in the reflected spectra reveals the amount of stress experienced by the reference and free sections and permits a qualitative and quantitative analysis of the stress applied by the package and the package's ability to protect fiber from stress (e.g. such as that imposed by a tension pull test). Measurements may be made after a variety of conditions are changed such as splice protector curing, axial tension application, axial tension release, time, and age accelerating environments. Comparative studies and various other calculations may also be performed to evaluate different packages.

The present invention provides a sensor system for sensing a parameter, comprising an optical source, coupler and signal processor system in combination with multiple structured fiber Bragg gratings. The optical source, coupler and signal processor system provide an optical source signal to the multiple structured fiber Bragg gratings. The optical source, coupler and signal processor system also responds to multiple structured fiber Bragg grating signals, for providing an optical source, coupler and signal processor system signal containing information about a sensed parameter. The multiple structured fiber Bragg gratings respond to the optical source signal, and further respond to the sensed parameter, for providing the multiple structured fiber Bragg grating signals containing information about a complex superposition of spectral responses or codes related to the sensed parameter. Each of the multiple structured fiber Bragg gratings includes a respective broadband spectral response or code related to the sensed parameter.

An apparatus for measuring at least one parameter associated with a fluid flowing within a pipe comprises an optical measurement device and a signal processor. The optical measurement device provides output signals indicative of unsteady pressures within the fluid at two or more axial locations along the pipe in response to light reflected from an outer surface of the pipe. The signal processor provides an output signal indicative of at least one parameter associated with the fluid in response to the output signals. The optical measurement device may include, for example, an electronic speckle pattern interferometer, a Fabry-Perot device, and / or a laser vibrometer. The at least one parameter may include at least one of: density of the fluid, volumetric flow rate of the fluid, mass flow rate of the fluid, composition of the fluid, entrained air in the fluid, consistency of the fluid, size of particles in the fluid, and health of a device causing the unsteady pressures to be generated in the pipe.

Disclosed herein is an accelerometer and / or displacement device that uses a mass coupled to a rhomboidal flexure to provide compression to an optical sensing element preferably having a fiber Bragg grating (FBG). The transducer includes a precompressed optical sensor disposed along a first axis between sides of the flexure. The top portion of the flexure connects to the mass which intersects the flexure along a second axis perpendicular to the first axis. When the mass experiences a force due to acceleration or displacement, the flexure will expand or contract along the second axis, which respectively compresses or relieves the compression of the FBG in the optical sensing element along the first axis. Perturbing the force presented to the FBG changes its Bragg reflection wavelength, which is interrogated to quantify the dynamic or constant force. A temperature compensation scheme, including the use of additional fiber Bragg gratings and thermal compensators axially positioned to counteract thermal effects of the optical sensing element, is also disclosed.

A dislodgement sensor for use with dialysis and other blood transfusion equipment that detects when a venous needle is dislodged from a patient. The sensor includes a photosensor attached to the venous needle or to tubing attached to the venous needle, an opaque cover placed over but not attached to the photosensor, and a signal line from the photosensor to the equipment. If the venous needle is dislodged, the photosensor is withdrawn from beneath the opaque cover, exposing the photosensor to light, which causes the photosensor to send a signal to the equipment indicating that the venous needle has been dislodged. Also, a method of using such a sensor.

Sensors, including fiber optic sensors and their umbilicals, are mounted on support structures designed to be retro-fitted to in-place structures, including subsea structures. The sensor support structures are designed to monitor structure conditions, including strain, temperature, and in the instance of pipelines, the existence of production slugs. Moreover the support structures are designed for installation in harsh environments, such as deep water conditions using remotely operated vehicles.

An optical sensor (10) that provides for concurrent pressure and temperature measurements at substantially the same location includes at least one launch fiber (22) and at least one temperature sensitive material (52) having a refractive index that changes with a change in temperature. The launch fiber and temperature sensitive material are spaced from each other across a gap (21) having length (L). A reflecting fiber (26) can be provided adjacent the temperature sensitive material. The optical sensor (10) also includes a sealed cavity (20). The launch fiber (22) and reflecting fiber (26) can be attached to the tube and at least partially disposed within the cavity. Changes in pressure change the length (L) of the gap (21).

According to embodiments of the present invention, a distributed pressure and shear stress sensor includes a flexible substrate, such as PDMS, with a waveguide formed thereon. Along the waveguide path are several Bragg gratings. Each Bragg grating has a characteristic Bragg wavelength that shifts in response to an applied load due to elongation / compression of the grating. The wavelength shifts are monitored using a single input and a single output for the waveguide to determine the amount of applied pressure on the gratings. To measure shear stress, two flexible substrates with the waveguide and Bragg gratings are placed on top of each other such that the waveguides and gratings are perpendicular to each other. To fabricate the distributive pressure and shear sensor, a unique micro-molding technique is used wherein gratings are stamped into PDMS, for example.

An electric cable includes a strain sensor longitudinally extending along the cable and including a strain optical fibre arranged within a bending neutral region surrounding and including a bending neutral longitudinal axis of the electric cable, and at least two longitudinal structural elements, at least one of the at least two longitudinal structural elements being a core including an electrical conductor, wherein the strain sensor is embedded in a strain-transferring filler mechanically coupling at least one of the at least two longitudinal structural elements with the strain sensor. With the disclosed cable construction, the strain experienced by the at least one of the at least two longitudinal structural elements is transferred to the strain sensor at least in a strained condition. In the preferred embodiments, the electric cable is a heavy-duty cable.

A garment and system includes a monitoring fabric that exhibits a light reflection property and substantially no light transmission property when the fabric is illuminated with light having wavelength(s) in the range of 400 to 2200 nanometers. The amount of useful light reflected by the fabric into an aperture of acceptance defined with respect to an axis extending from the fabric relative to the amount of light lost to the aperture of acceptance detectably changes when the fabric stretches in response to motion, as the motion induced by physiological activity (e.g., heart rate). The system includes at least one radiation source and at least one radiation detector, with the detector disposed in the aperture of acceptance. The source and detector may be attached to the fabric in relative positions such that the reception of incident radiation by the detector is directly affected by a change in the amount of useful light reflected by the fabric into the aperture of acceptance as the fabric stretches in response to motion.

Broadband energy incident on a transducer having partially or fully reflective surfaces separated by a gap which is greater than the coherence length of the broadband energy but smaller than one-half a coherence length of a band of energy within said broadband energy causes a portion of the spectral content of the broadband energy corresponding to a coherence length greater than twice the gap length to exhibit interference effects while the average power of the broadband energy remains unaffected. Splitting energy reflected from the transducer into two beams which are filtered at preferably similar center frequencies but with different pass bands yields beams which are radically different in sensitivity to changes in gap length. Analyzing the beams to derive a ratio of powers (since source intensity and fiber attenuation in a common fiber are thus self-cancelling) allows high accuracy and high resolution absolute measurement of temperature, pressure or strain. Effects of any of these physical parameters which are not of interest in a measurement can be fully compensated or made arbitrarily insignificant in a simple transducer structure of extremely small size. Use of broadband energy permits measurement over greater lengths of optical fiber.

The fiber optic pressure sensing system includes a sensor housing formed using MEMS processing. The sensor housing has ribs and grooves in both horizontal and vertical directions relative to the surface to allow the membrane to flex in a consistent manner. The flexing of the membrane allows the pedestal to be repeatedly positioned in response to pressure acting on the extension of the sensor head and membrane.

A portion of a polarization maintaining (PM) optical fiber having two polarization states is analyzed. First and second spectral responses of the PM fiber portion are determined. In a preferred implementation, the spectral responses are determined using Optical Frequency Domain Reflectometry (OFDR). Each polarization state of the PM fiber portion has a corresponding spectral component in the first spectral response. First and second spectral analyses of the PM fiber portion are performed using the first and second spectral responses. Based on those spectral analyses of the PM fiber portion, a first physical characteristic affecting the PM fiber portion is determined that is distinct from a second different physical characteristic affecting the fiber portion. Example physical characteristics include temperature and strain. An output signal related to the first physical characteristics affecting the fiber portion is provided, e.g., for display, further processing, etc.