Abstract: Disclosed is a signal processing method for a distributed acoustic sensing system (DAS), where a scattered signal that was scattered at a scattering location along an optical path is received and interfered with a local oscillator signal to generate a first carrier signal that is modulated by a phase difference between the local oscillator signal and the scattered signal. The first carrier signal is then digitally processed in order to generate a second carrier signal that is modulated by a spatial differential of the phase difference. The spatial differential of the phase difference is directly related to the strain (or acoustic environment) of the optical path at the scattering location, and so enables the strain at the scattering location to be estimated.

Abstract: A method includes generating a sequence of multiple optical pulses, for transmission into an optical fiber (12) having an array of multiple equally spaced reflectors (14) embedded therein, the sequence having a pulse duration and a pulse repetition interval (PRI) that guarantee that reflections of any of the optical pulses from any of the reflectors do not overlap. The sequence of optical pulses is transmitted into the optical fiber. The reflections of the optical pulses from the reflectors are extracted from the optical fiber. One or more events affecting the optical fiber are identified by analyzing the reflections.

Abstract: A method (1000) of improving the operation of a wellbore (1), said wellbore (1) including a drill pipe (2) in which a fluid (3) circulates and an optical fiber (5) positioned outside the drill pipe (2). The circulation of said fluid (3) is controlled at least in part by an outlet valve (4a) and/or an injection valve (4b). The method includes steps of generating (100) two digital orthogonal backscatter signals from at least one light signal, preferably polarized, injected into said optical fiber (5), and controlling (400) the opening of injection and/or outlet valves (4) depending on the two digital orthogonal backscatter signals.

Abstract: A method for enabling light detection and ranging (LiDAR) scanning is provided. The method is performed by a system disposed or included in a vehicle. The method comprises receiving a first laser signal. The first laser signal has a first wavelength. The method further includes generating a second laser signal based on the first laser signal. The second laser signal has a second wavelength. The method further includes providing a plurality of third laser signals based on the second laser signal; and delivering a corresponding third laser signal of the plurality of third laser signals to a respective LiDAR scanner of the plurality of LiDAR scanners. Each of the LiDAR scanners are disposed at a separate location of the vehicle such that each of the LiDAR scanners is capable of scanning a substantial different spatial range from another LiDAR scanner. LiDAR systems can use multi-wavelength to provide other benefits as well.

Abstract: In some examples, fiber optic virtual sensing may include generating, by a virtual sensor generator that is operatively connected to a device under test (DUT), at least one virtual sensor along the DUT. A DUT interrogator may be operatively connected to the DUT to transmit a stimulus optical signal into the DUT. The DUT interrogator may analyze reflected light resulting from the transmitted stimulus optical signal. The DUT interrogator may determine, based on the analysis of the reflected light, an attribute of the DUT sensed by the at least one virtual sensor.

Abstract: An intelligent skin based on a small-size distributed optical fiber sensing array. The intelligent skin includes an epidermis sensing array, an embedded optical fiber sensing array, a data collection system module, and a data processing mode recognition module. The body of the intelligent skin is made of a flexible material. The embedded optical fiber sensing array in an epidermis includes a plurality of all-fiber interferomatic sensing arrays. The data collection system module includes a broadband light source, an optical combiner/splitter, an optical path change-over switch, a signal detector and a computer. The data processing mode recognition module includes mode recognition and training of a neural network. The intelligent skin further includes an external display software used to perform intelligent sensing recognition for sense of touch, position, shape, and ingredient, temperature and vibration of an object and so on.

Abstract: An apparatus includes an optical source of an optical wavelength carrier, an optical modulator to receive the optical wavelength carrier, and an optical data receiver. The optical data modulator is configured to produce, from the optical wavelength carrier, an optical signal to carry separate data on different first and second components thereof in individual modulation periods during data transmission and to carry a training sequence on one of the components during time slots for calibration. The first component is relatively phase offset from the second component in the optical signal. The optical data modulator alternates the one of the components between the first and second components over the time slots for calibration. The optical receiver is connected to receive a portion of the optical signal and to temporally interleave a measurement of a characteristic of the first component and a measurement of a characteristic of the second component over the time slots for calibration.

Abstract: Narrow-optical linewidth laser generation devices and methods for generating a narrow-optical linewidth laser beam are provided. One narrow-optical linewidth laser generation devie includes a single-wavelength mirror or multiwavelength mirror (for comb lasers) formed from one or more optical ring resonators coupled with an optical splitter. The optical splitter may in turn be coupled with a quantum dot optical amplifier (QDOA), itself coupled with a phase-tuner. The phase tuner may be further coupled with a broadband mirror. The narrow-optical linewidth laser beam is generated by using a long laser cavity and additionally by using an integrated optical feedback.

Abstract: This application described methods and apparatus for distributed fibre optic sensing. A sensing apparatus has a modulator which modulates radiation from an optical source to interrogate a sensing optical fibre with a first interrogation pulse at a first frequency (F1) and a second interrogation pulse at a second, different, frequency (F2), both different in frequency from a local oscillator (LO). A mixer mixes backscatter from the sensing optical fibre with the local oscillator and supplies the mixed signal to a detector that provides a corresponding digital signal. A processor processes the digital signal (DX, DY) in a first and second processing channels to demodulate respective first and second phase signals based on the respective frequency difference between the first and second frequency and the local oscillator and determines a temporal difference between the first and second phase signals.

Abstract: An optical shape sensing method is provided.

Abstract: The present invention belongs to the technical field of joint surface pressure detection of connecting pieces, and provides an FBG sensor-based bolt fastening joint surface pressure detection method, comprising the steps of determining the size and the position of an FBG sensor; and determining the pressure of a joint surface measuring position on the basis of the single bolt connection joint surface pressure distribution theory, and completing calibration in real-time correspondence to the strain and pressure values to realize precise detection of the joint surface pressure. Determining the size and the position of the FBG sensor embedding slot according to the above method can ensure the reliability and accuracy of strain information; and an accurate strain-joint surface pressure curve can be obtained in combination with the determination of the joint surface pressure, which provides a practical and feasible method for the research on the bolt connection joint surface pressure.

Abstract: In some examples, fiber optic virtual sensing may include generating, by a virtual sensor generator that is operatively connected to a device under test (DUT), at least one virtual sensor along the DUT. A DUT interrogator may be operatively connected to the DUT to transmit a stimulus optical signal into the DUT. The DUT interrogator may analyze reflected light resulting from the transmitted stimulus optical signal. The DUT interrogator may determine, based on the analysis of the reflected light, an attribute of the DUT sensed by the at least one virtual sensor.

Abstract: The present invention provides novel apparatus and methods for fast quantitative measurement of perturbation of optical fields transmitted, reflected and/or scattered along a length of an optical fibre. The present invention can be used for point sensors as well as distributed sensors or the combination of both. In particular this technique can be applied to distributed sensors while extending dramatically the speed and sensitivity to allow the detection of acoustic perturbations anywhere along a length of an optical fibre while achieving fine spatial resolution. The present invention offers unique advantages in a broad range of acoustic sensing and imaging applications. Typical uses are for monitoring oil and gas wells such as for distributed flow metering and/or imaging, seismic imaging, monitoring long cables and pipelines, imaging within large vessel as well as for security applications.

Abstract: In a Brillouin sensing system using optical microwave frequency discriminators and a scrambler provided by the present invention, a laser signal outputted by a distributed feedback laser is divided into two paths of optical signals through a coupler, one path of optical signal is modulated by a modulator to act as a pump light signal and then is transmitted to sensing fibers through a circulator; another path of optical signal is modulated by another modulator to act as a detecting light signal and then directly enters the sensing fibers. When the frequency difference between the pump light and the detecting light is equal to the Brillouin frequency shift of a certain region in the fibers, the region produces the stimulated Brillouin scattering effect, so that through determining the frequency shift and power of the Brillouin scattering signal, the temperature and stress of the sensing fibers are obtained.

Abstract: Various embodiments provide for an integrated temperature sensor and microphone package where the temperature sensor is located in, over, or near an acoustic port associated with the microphone. This placement of the temperature sensor near the acoustic port enables the temperature sensor to more accurately determine the ambient air temperature and reduces heat island interference cause by heat associated with the integrated circuit. In an embodiment, the temperature sensor can be a thermocouple formed over a substrate, with the temperature sensing portion of the thermocouple formed over the acoustic port. In another embodiment, the temperature sensor can be formed on an application specific integrated circuit that extends into or over the acoustic port. In another embodiment, a thermally conductive channel in a substrate can be placed near the acoustic port to enable the temperature sensor to determine the ambient temperature via the channel.

Abstract: A pluggable optical connector is configured to be insertable into and removable from an optical communication apparatus, and to be capable of communicating a modulation signal and a data signal with the optical communication apparatus. A wavelength-tunable light source is configured to output an output light and a local oscillation light. An optical transmission unit is configured to output an optical signal generated by modulating the output light in response to the modulation signal. An optical reception unit is configured to demodulate an optical signal received by using the local oscillation light to the data signal. Pluggable optical receptors are configured in such a manner that an optical fiber is insertable into and removable from the pluggable optical receptors, and configured to be capable of outputting the optical signal to the optical fiber and transferring the optical signal received thorough the optical fiber to the optical reception unit.

Abstract: A high-speed interrogation system is provided for interferometric sensors, one example of which is an EFPI sensor, that operates based on spectral interference. The system uses a two mode operation that includes a lower speed, accurate absolute measurement mode and a higher speed, relative measurement mode. The system achieves greater overall measurement accuracy and speed than known sensor interrogation approaches.

Abstract: A well system includes a target wellbore that penetrates a subterranean formation and a relief wellbore drilled toward the target wellbore and a target intercept location where a fluid flows into the target wellbore from the subterranean formation. A bottom hole assembly is coupled to a drill string extended into the relief wellbore and includes a fiber optic ranging assembly having one or more fiber optic sensors positioned on a tubular member. The fiber optic sensors measure at least one of acoustic energy and thermal energy emitted by the fluid as it flows into the target wellbore. A computer system is communicably coupled to the one or more fiber optic sensors to process measurements of the fluid obtained by the one or more fiber optic sensors.

Abstract: A method for estimating an environmental parameter includes transmitting a first interrogation signal into an optical fiber, receiving a reflected return signal including light reflected from one or more of the plurality of FBG's in the fiber and receiving at a processor data describing the reflected return signal. The received data is comparted to expected data to determine a shift in wavelength of light reflected for one or more of the plurality of FBGs and a change in a length of a dead zone of the optical fiber based on the comparison is also determined. From this, estimates of locations two or more of the plurality of FBG's are formed.

Abstract: A photonic integrated circuit wavelength tunable laser device includes a gain element integrated into a photonic integrated circuit. The gain element provides optical gain to an optical signal. A tunable filter is integrated into the photonic integrated circuit. A modulator is integrated into the photonic integrated circuit that modulates the optical signal as a function of time, wherein the gain element, the tunable filter, and the modulator form a wavelength tunable laser device having a wavelength that tunes as a function of time.

Abstract: An optical sensor and corresponding method of operation can detect a phase transition and/or related property of a hydrocarbon-based analyte. The optical sensor includes an optical element with a metallic film coupled or integral thereto, with a sample chamber holds the hydrocarbon-based analyte such that the hydrocarbon-based analyte is disposed adjacent the metallic layer. The optical sensor further includes a light source configured to direct light through the optical element such that the light is reflected by the metallic layer under conditions of surface plasmon resonance. The optical sensor analyzes the reflected light to detect a phase transition and/or related property of a hydrocarbon-based analyte.

Abstract: The invention relates to a method of interrogating an interferometric optical fiber sensor system including a laser source configured to generate interrogation light and a sensor array with at least a first reflector and a second reflector.

Abstract: A Fiber Bragg grating (FBG) sensor structure, a method of fabricating a FBG sensor structure, and a method of employing a FBG sensor structure comprising an optical fiber portion having at least one FBG formed therein. The FBG sensor structure comprises an optical fiber portion having at least one FBG formed therein; and a sleeve structure capable of transferring vibrations and/or strain along a length thereof; wherein the optical fiber portion is coupled to the sleeve structure such that the central wavelength of the FBG, is variable under the transferred vibrations and/or strain.

Abstract: A distributed fiber optic cable comprises an elongate body and a first optical fiber longitudinally housed in the body, wherein the fiber describes a sinusoid having an amplitude and a first wavelength along the length of the body and wherein the sinusoid rotates along the length of the body so as to describe a twisted sinusoid having a twist wavelength. A method for sensing an acoustic wave comprises a) providing a set of signals collected from the cable, b) processing the signals so as to divide the fiber in each twist wavelength of cable into a predetermined number of channels, c) measuring the amplitudes in each channel and calculating the maximum and minimum amplitude in a preselected length of cable, d) using the calculated maximum and minimum for the preselected length of cable to determine the amplitude and direction of the wave at the preselected length of cable.

Abstract: A confocal chromatic device is provided, including at least one chromatic lens with an extended axial chromatism; at least one broadband light source; at least one optical detector; and at least one measurement channel with a planar Y-junction made with a planar waveguide optics technology, and arranged for transferring light from the at least one light source towards the at least one chromatic lens and for transferring light reflected back through the at least one chromatic lens towards the at least one optical detector.

Abstract: Method and apparatus are disclosed for use of a fiber-optic sensor loop for use within a wellbore; with a plurality of light sources optically coupled to the fiber-optic sensor loop; at least one electromagnetically sensitized region within the fiber-optic sensor loop; and a plurality of detectors optically coupled to the fiber-optic sensor loop; and using the sensing system to detect changes in a magnetic field within the wellbore.

Abstract: The application describes methods and apparatus for distributed fiber sensing, especially distributed acoustic/strain sensing. The method involves launching at least first and second pulse pairs into an optical fiber, the first and second pulse pairs having the same frequency configuration as one another and being generated such that the phase relationship of the pulses of the first pulse pair has a predetermined relative phase difference to the phase relationship of the pulses of the second pulse pair. In one embodiment there is a frequency difference between the pulses in a pulse pair which is related to the launch rate of the pulse pairs. In another embodiment the phase difference between the pulses in a pair is varied between successive launches. In this way an analytic version of the backscatter interference signal can be generated within the baseband of the sensor.

Abstract: The invention relates to a system (1) comprising a deformable surface (2) and a first and a second sensor (C1, C2) designed to provide a first and a second measurement signal (S1, S2) intended to be collected by a processing circuit (12), said system (1) comprising first and second measurement paths (V1, V2) for collecting the first and second measurement signals (S1, S2), said system (1) being characterized in that it comprises a common calibration member (20) for simultaneously injecting into the first and second measurement paths (V1, V2) a calibration signal (SE), said common calibration member (20) being designed so that the image signals (S?1, S?2, S?n) restored via said measurement paths (V1, V2, Vn) are independent of said movable surface (2). Deformable movable surface systems, of the deformable mirror type.

Abstract: An example telemetry signal detection apparatus may include a optical splitter, a light source optically coupled to the optical splitter, and a light detector optically coupled to the optical splitter. The apparatus further may include a reference loop optically coupled to the optical splitter and a sensor loop optically coupled to the reference loop and the optical splitter. The reference loop may be contained within a reference loop enclosure. The sensor loop and reference loop may comprise a zero-area Sagnac loop with folded optical fiber or dual fiber cable configurations.

Abstract: There is described a sensor apparatus. It comprises an interrogator comprising a light source emitting pulses having a wavelength about an average wavelength; and a fiber Bragg grating (FBG) arrangement. The arrangement comprises a FBG sensor array comprising a plurality of FBG sensors on an optical fiber and being for reflecting the pulses, thereby producing reflected pulses at each one of the FBG sensors. FBG sensors of a given FBG sensor array have a spatial separation therebetween which is sufficient to allow, at a receiver, a temporal discrimination between the reflected pulses produced by each one of the FBG sensors. The FBG sensor array has a spectral reflection window which comprises the average wavelength.

Abstract: An optical imaging system includes an optical radiation source (410, 510), a frequency clock module outputting frequency clock signals (420), an optical interferometer (430), a data acquisition (DAQ) device (440) triggered by the frequency clock signals, and a computer (450) to perform multi-dimensional optical imaging of the samples. The frequency clock signals are processed by software or hardware to produce a record containing frequency-time relationship of the optical radiation source (410, 510) to externally clock the sampling process of the DAQ device (440). The system may employ over-sampling and various digital signal processing methods to improve image quality. The system further includes multiple stages of routers (1418, 1425) connecting the light source (1410) with a plurality of interferometers (1420a-1420n) and a DAQ system (1450) externally clocked by frequency clock signals to perform high-speed multi-channel optical imaging of samples.

Abstract: A distributed optical fiber sensing system is provided. The system can include an interrogator, a transmission optical fiber, a sensing optical fiber, and a reflector. Each of the transmission optical fiber and the sensing optical fiber includes at least one circulator. The reflector is optically coupled to the transmission optical fiber for sensing separate regions along the sensing optical fiber.

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: Optical-based apparatus and method for sensing parameters in connection with an asset, such as a pipeline, are provided. At least two sites in an optical fiber may include a respective fiber grating arranged to have a respective optical response in a wavelength spectrum having a distinguishing feature indicative of a value of a respective local parameter at a respective grating site. The two fiber gratings may be further arranged to form, in combination with a respective portion of the optical fiber which extends between the two sites, respective optical backscatter portions that when combined with one another are effective to sense an optical change in the fiber portion between the sites indicative of a value of a distributed parameter. This is a parameter modality different from a parameter modality of the respective local parameters at the respective grating sites.

Abstract: A temperature measuring method for measuring a temperature of a member corresponding to a measuring object arranged within a chamber of a plasma processing apparatus is provided. The temperature measuring method involves obtaining a function (f) for correcting a correction target temperature (Tmeas) according to a measurement window temperature (Tw), the function (f) being computed based on the correction target temperature (Tmeas) corresponding to a temperature of the measuring object measured via a measurement window arranged at the chamber, a reference temperature (Tobj) corresponding to a temperature of the measuring object measured without using the measurement window, and the measurement window temperature (Tw) corresponding to a temperature of the measurement window.

Abstract: Deformation measurement sensor operating in a hostile environment and including an optical movement measurement module, and measurement system using said sensor. The sensor includes: an enclosure comprising an opening; a movable element having a first surface that is brought into contact with an object (4) that can deform, for example a nuclear fuel rod, and a second surface that is reflective and extends into the enclosure through the opening; a sealed, resilient connecting component performing a return function between the element and the enclosure; and, inside the enclosure, a module for creating an interference light using a light reflected by the second surface of the element. Deformation of the object results in a modification to the interference light that is representative of the deformation.

Abstract: An input of an optical interferometer is a periodical optical pulse. A phase of a first half and a latter half of a reference pulse is a 90 degree (independently orthogonal) phase difference. Two interferometric outputs i1 and i2, where the phase difference is 90 degrees from each other, are obtained by interference of the reference pulse and the signal pulse. ? is calculated by referring the amplitude of reference pulse and the signal pulse to remove the light intensity fluctuations. Two values of cos ?1 and cos ?2 are calculated and positions are determined on the cosine curve by obtaining ?1 and ?2 values. ??1 and ??2, which are the phase increment or decrement of both ?1 and ?2 in a T period, are summed and becomes the sensor output signal that removes the measurement range limitation of ±90 degrees (a half wavelength of light) of the light phase.

Abstract: The invention relates to a method for detecting crack formation in a hoisting member, comprising the steps of measuring a stress under load at two points of the hoisting member, comparing the measured stresses and generating a warning signal when the measured stresses differ too much from each other. The invention also relates to a device for detecting crack formation in a hoisting member, comprising means arranged at two points of the hoisting member for measuring a stress under load, means connected to the measuring means for comparing the measured stresses, and means connected to the comparing means for generating a warning signal when the measured stresses differ too much from each other. Finally, the invention relates to a hoisting frame, comprising a number of hoisting members which are mounted thereon close to its corners, and crack detection devices connected thereto.

Abstract: A displacement sensor for sensing the displacement of a movable component of a device is provided. A flexible element of the displacement sensor includes a mounting portion mounted to the device and a coupling portion spaced apart from the mounting portion. A displacement conversion mechanism is coupled to the movable component and is further coupled to the coupling portion of the flexible element. The displacement conversion mechanism is configured to convert a larger displacement of the movable component into a smaller displacement of the coupling portion of the flexible element. The flexible element is arranged such that a displacement at the coupling portion causes the flexible element to bend.

Abstract: A displacement sensor for sensing the displacement of a movable component is provided. The displacement sensor includes a displacement transmission mechanism configured to reduce a large displacement provided at its input into a smaller displacement at its output. The displacement sensor further includes a fiber optic displacement sensor, wherein the output of the displacement transmission mechanism is coupled to the fiber optic displacement sensor.

Abstract: A system for remotely sensing a target material in situ include a broad-band laser source, at least one tunable filter coupled to the source laser for generating a swept-frequency signal an optical device for splitting the swept-frequency signal into a first illumination signal and second illumination signal, a first optical path for directing the first illumination signal unto the target material and receiving a reflected signal from the target material, a second optical path for receiving the second illumination signal and generating a spectral reference signal, and a controller coupled to the first optical path and the second optical path for adjusting the frequency and spatial resolution of the laser source based at least in part on a comparison of the spectral reference signal and the reflected signal.

Abstract: A bearing comprises a Bragg grated optical fiber to measure one or more parameters of the bearing such as load, temperature, acceleration/vibration and identification. To be able to fit as many Bragg gratings as possible, the utilization of the corresponding frequency plane output is optimized by having low bandwidth next to large bandwidth sensors in the frequency place. The corresponding physical sensors such as load sensors on a bearing will not be adjacent. Sensors in the loaded zone are giving a high bandwidth output and sensors in the un-loaded zone are giving a low bandwidth output, thus even though these are not physically adjacent, the corresponding frequency areas are adjacent by appropriate grating.

Abstract: The present disclosure is generally directed to a strain sensor, system and method of fabrication and use that includes an optical fiber, an optical signal generator that transmits an optical signal through the optical fiber, at least two photonic crystal slabs within the optical fiber separated by a first segment of optical fiber, a photo-detector that detects a reflected optical signal from the at least two photonic crystal slabs, and a processor that computes a mechanical strain over the first segment of optical fiber based on the reflected optical signal detected by the photo-detector.

Abstract: A surgical instrument that includes a housing linkable with a manipulator arm of a robotic surgical system, a shaft coupled to the housing, a force transducer on a distal end of the shaft, and a plurality of fiber optic strain gauges on the force transducer is disclosed. The plurality of strain gauges are coupled to a fiber optic splitter or an arrayed waveguide grating (AWG) multiplexer, which can be coupled to a fiber optic connector. A wrist joint coupled to an end effector is coupled to a distal end of the force transducer. A robotic surgical manipulator that includes a base link coupled to a distal end of a manipulator positioning system, and a distal link with an instrument interface, and a fiber optic connector optically linkable to a surgical instrument. A method of passing data between an instrument and a manipulator via optical connectors is also provided.

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

Abstract: An interferometric measurement system suppresses cross talk between optical waveguides used to measure one or more parameters. A first interferometric measurement channel coupled to a first waveguide, and a second interferometric measurement channel coupled to a second waveguide. At least one of the channels includes a reference light path in addition to the first and second waveguides. A reference path optical delay is associated with the reference light path, a first optical delay is associated with the input portion of at least one of the first and second interferometric measurement channels, and a second optical delay is associated with an output portion of the one interferometric measurement channel. A value of the first optical delay and a value the second optical delay are chosen to suppress crosstalk associated with the other of the first and second interferometric measurement channels in the one interferometric measurement channel over a predetermined length of the first waveguide.

Abstract: Interrogation of a phase based transducer is performed by temporally overlapping and interfering a single pulse output from the transducer to determine the rate of change with time of the measurand represented as a phase change. The rate of change, or derivative of the phase change typically has a much smaller amplitude than the signal itself, and the derivative measurement therefore has reduced sensitivity. In this way, large amplitude signals which might otherwise be subject to overscaling effects can be measured more effectively.

Abstract: A personnel monitoring system. The personnel monitoring system includes a host node having an optical source for generating optical signals, and an optical receiver. The personnel monitoring system also includes a plurality of fiber optic sensors for converting at least one of vibrational and acoustical energy to optical intensity information, each of the fiber optic sensors having: (1) at least one length of optical fiber configured to sense at least one of vibrational and acoustical energy; (2) a reflector at an end of the at least one length of optical fiber; and (3) a field node for receiving optical signals from the host node, the field node transmitting optical signals along the at least one length of optical fiber, receiving optical signals back from the at least one length of optical fiber, and transmitting optical signals to the optical receiver of the host node.

Abstract: A method and system for rendering the shape of a multi-core optical fiber or multi-fiber bundle in three-dimensional space in real time based on measured fiber strain data. Three optical fiber cores arc arranged in parallel at 120° intervals about a central axis. A series of longitudinally co-located strain sensor triplets, typically fiber Bragg gratings, are positioned along the length of each fiber at known intervals. A tunable laser interrogates the sensors to detect strain on the fiber cores. Software determines the strain magnitude (?L/L) for each fiber at a given triplet, but then applies beam theory to calculate curvature, beading angle and torsion of the fiber bundle, and from there it determines the shape of the fiber in s Cartesian coordinate system by solving a series of ordinary differential equations expanded from the Frenet-Serrat equations.

Abstract: The present invention is directed to an assembly for use in detecting an analyte in a sample based on thin-film spectral interference. The assembly comprises a waveguide, a monolithic substrate optically coupled to the waveguide, and a thin-film layer directly bonded to the sensing side of the monolithic substrate. The refractive index of the monolithic substrate is higher than the refractive index of the transparent material of the thin-film layer. A spectral interference between the light reflected into the waveguide from a first reflecting surface and a second reflecting surface varies as analyte molecules in a sample bind to the analyte binding molecules coated on the thin-film layer.