Abstract: There is provided an optical fiber temperature distribution measuring device which measures a temperature distribution along an optical fiber (3) using backward Raman scattering light generated in the optical fiber. The device includes: a reference temperature thermometer (11) disposed in the vicinity of the optical fiber so as to measure a reference temperature (T1, T2) of the optical fiber; an arithmetic controller (7) that calculates a temperature (T) of the optical fiber based on the backward Raman scattering light; and a temperature corrector (12) that corrects the calculated temperature (T) based on a correction formula containing the reference temperature as a parameter.

Abstract: This invention teaches the fiber optic sensors temperature sensors for cryogenic temperature range with improved sensitivity and resolution, and method of making said sensors. In more detail, the present invention is related to enhancement of temperature sensitivity of fiber optic temperature sensors at cryogenic temperatures by utilizing nanomaterials with a thermal expansion coefficient that is smaller than the thermal expansion coefficient of the optical fiber but larger in absolute value than the thermal expansion coefficient of the optical fiber at least over a range of temperatures.

Abstract: Systems and methods for extending the range of a fiber optic DTS system are provided. In one respect, a method may provide steps for transmitting, in a first time period, an optical signal at a first energy level through an optical fiber, collecting backscatter signals as a result of the first transmission, adjusting the first energy level to a second energy level, transmitting, in an additional time period, the adjusted optical signal through the optical fiber, collecting backscatter signals as a result of the adjusted transmissions, and using a portion of the collected backscatter as a result of the first transmission and a portion of the collected backscatter as a result of the additional transmissions, determining one or more parameter profiles, such as a temperature profile.

Abstract: Various embodiments of thermal sensing systems and methods for monitoring thermal conditions in such material processing assemblies are described. The thermal sensing systems include a sensor cable that incorporates or is coupled to one or more thermal sensors. The sensor cable is positioned in the assembly and the thermal sensors provide temperature measurements. In various embodiments, the sensor cable and thermal sensors may be optical or electrical devices.

Abstract: An optical fiber with long period fiber gratings includes an optical fiber axis, a core region extending along the fiber axis, the core region having a core refractive index, a cladding region surrounding the core region, the cladding having a cladding refractive index, and a plurality of microholes perpendicular to the fiber axis with a portion of the core region removed, the plurality of microholes are spaced apart by a grating period.

Abstract: An optical fiber temperature sensor includes an optical transceiver module, a transmission fiber and a sensing head. When the transmission fiber is a polarization maintaining fiber, the sensing head includes a temperature sensing element and a fiber reflector, the temperature sensing element is a section of polarization maintaining fiber. The transmission fiber is fusion spliced with the temperature sensing element, an angle between a polarization axis of the transmission fiber and that of the temperature sensing element is 45 degree at the fusion splicing point. When the transmission fiber is a single-mode fiber, the sensing head includes a polarizer. An angle between a polarization axis of the polarization maintaining fiber connecting the temperature sensing element with the polarizer and that of the polarization maintaining fiber of the temperature sensing element is 45 degree at the fusion splicing point. The present invention is of simple principle and structure, and facilitates manufacturing.

Abstract: A single fiber Mach-Zehnder interferometer comprises an optical fiber having a core region and a cladding surrounding the core region, and a micro-cavity having part of the cladding and the core region removed, wherein the micro-cavity is adapted to receive a light beam and separate the light beam into a first light beam that propagates through the micro-cavity in an unguided mode, and a second light beam that propagates through the core region in a guided mode.

Abstract: Systems and methods are disclosed for distributed temperature and strain sensing along a length of an infrastructure. Two optical sources, such as, external cavity lasers with a narrow linewidth, are used for launching a probe signal into a sensing fiber coupled to the infrastructure, and for producing a local oscillation signal, respectively. The optical sources are coherently locked with a predefined frequency offset with respect to each other, the predefined frequency offset being in the order of the Brillouin frequency shift. The optical sources are included in an optical phase lock loop (OPLL) system. A balanced heterodyne receiver for narrow band detection at radio frequency (RF) bandwidth receives an optical signal generated by coherent mixing of a backscattered probe signal with the Brillouin frequency shift and the local oscillation signal, and produces an output indicative of one or both of a measured temperature and a measured strain.

Abstract: Apparatus for a spatially resolved temperature measurement, with at least one optical fiber (6) for the spatially resolved temperature measurement, and at least one laser light source (2) producing light (3, 23) which can be coupled into the optical fiber (6), wherein the portions of the light (3, 23) backscattered in the optical fiber (6) can be coupled out of the optical fiber (6) and evaluated. The apparatus further includes means for reducing polarization-induced effects, wherein the means may be, for example, a polarization modifier (4) capable of at least partially depolarizing the light (3).

Abstract: A distributed optical fiber sensor system is provided. In this system, backward-scattered light generated in a test optical fiber is filtered to separate the backward-scattered light into Raman scattered light and Brillouin scattered light. The separated Raman scattered light and Brillouin scattered light are each converted into digital data. A change in temperature with respect to the distance of the test optical fiber is measured from the digital data of the Raman scattered light. A change in temperature and a change in the degree of deformation with respect to the distance of the test optical fiber are measured from the digital data of the Brillouin scattered light. The change in temperature and the change in the degree of deformation with respect to the distance of the test optical fiber are separately output using the measured data.

Abstract: An optical fibre temperature sensor comprising: an optical pulse generator; an optical fibre into which said optical pulses are fed; an optical receiver to receive said optical pulses reflected by said optical fibre and to convert them into an electrical signal; a processor which receives said electrical signal and determines the temperature along said optical fibre; said optical receiver comprising a first filter and a second filter to filter said optical pulse reflected by said optical fibre, characterised in that said first and said second filters filter two adjacent portions of anti-Stokes optical signals or of Stokes optical signals

Abstract: A method and apparatus is provided for determining when a battery, or one or more batteries within a battery pack, undergoes an undesired thermal event such as thermal runaway. The system uses an optical fiber mounted in close proximity to, or in contact with, an external surface of the battery or batteries to be monitored. A source of light is optically coupled to the input facet of the optical fiber and a detector optically coupled to the output facet of the optical fiber. Battery health is determined by monitoring the light transmitted through the optical fiber.

Abstract: An automatic and continuous method is presented to improve the accuracy of fiber optic distributed temperature measurements derived from Raman back scatterings utilizing two light sources with different wavelengths, by choosing the wavelengths of the two sources so the primary source's return anti-Stokes component overlaps with the incident wavelength of the secondary light source thereby canceling out the non-identical attenuations generated by the wavelength differences between Stokes and anti-Stokes bands.

Abstract: The present invention relates to an apparatus, which works according to galvanic principles, in particular to a lithium-ion accumulator or, respectively, a lithium-ion cell, with at least two electrode devices (10; 20), in particular, a cathode and an anode, in particular, a separator device (30), arranged between two electrode devices, the apparatus (2) comprises, according to the invention, at least one or a plurality of glass fibers (18, 28, 38) which are configured or, respectively, operable as temperature sensor. It can comprise a net (16, 26, 36) formed by glass fibers, or an arrangement of a plurality of glass fibers, which are arranged substantially in parallel to each other, wherein at least one glass fiber (18, 28, 38) is configured or operable as temperature sensor.

Abstract: An optical fiber based polymer core sensor includes an optical fiber having a core and an end having a cured polymer core affixed to the core of the optical fiber. The cured polymer core extends outward from the end of the optical fiber and has a diameter approximately equal to the core of the optical fiber. Note the cured polymer core can be substantially cylindrical, tapered or geometrically shaped.

Abstract: A new step-index multimode pure silica core fiber for DTS (Distributed Temperature Sensing) system particularly useful for downhole environments is disclosed and described. The new sensor system provides optimum tradeoffs between coupling power, spatial resolution, and temperature resolution.

Abstract: A distributed temperature sensor (10) for cables configurations including at least one optical waveguide (12), the waveguide is constructed from a material with a predefined melting point, a light source (13) which is configured to emit light into the sensing optical waveguide (12), end a detector (14) configured to detect transmitted light intensity from the sensing optical waveguide (12) and an interlock module (15) configured to perform a shutdown of high power fiber coupled laser diodes (11), according to the signal detected by detector (14).

Abstract: The present invention relates to an optical fiber temperature sensor capable of reducing an error in a temperature measurement. The sensor comprises an optical fiber, an optical frequency difference adjusting section, a light source system, a spectrum measuring section, a temperature calculating section, and a correcting section. The light source system outputs, into different ends of the optical fiber, probe light and pumping light of which each center frequency is set corresponding to an instruction from the optical frequency difference indicating section respectively. The temperature calculating section calculates a temperature of an object based on BGS in a first domain measured by the spectrum measuring section. On the other hand, the correcting section outputs a correction instruction to the light source system so that BGS center frequency of a second domain may be in agreement with a reference value thereof.

Abstract: A multiple sensor fiber optic sensing system. A method of sensing distributed temperature and at least another property in a well includes the steps of: interconnecting an optical switch to an optical fiber which extends along a wellbore in the well; operating the optical switch to optically connect the optical fiber to an interferometric measurement system; and operating the optical switch to optically connect the optical fiber to a distributed temperature measurement system. Another method includes the steps of: installing an optical fiber along a wellbore in the well, the optical fiber being a first distributed temperature sensor, the installing step including providing a substantial length of the optical fiber proximate a second sensor which senses the well property; and calibrating the second sensor using a temperature sensed by the first sensor in the substantial length of the optical fiber.

Abstract: A method for monitoring a status of a sleeve for lining a system of pipes or conduits, the sleeve being impregnated with a curable resin, includes the steps of providing the sleeve, disposing at least one fiber optic sensor in thermally conductive contact with the sleeve, and generating, using the at least one fiber optic sensor, a positionally resolved thermographic image representative of a temperature of the sleeve as a function of position and time

Abstract: A sensing fibre for use in a distributed temperature sensing system comprises an optical fibre to be deployed in a measurement region in which a temperature measurement is to be made, which incorporates a reflective element, such as a join between portions of fibre, and a coiled fibre portion positioned adjacent a distal side of the reflective element, the coiled fibre portion contributing substantially nothing to the spatial extent of the optical fibre when deployed. In use, the effect of any forward propagating light incident on the reflective element that is returned for detection by the system, and which saturates the detector, can be eliminated by removing the part of the detected signal that corresponds to the coiled portion, after which the detector will have recovered. The remaining parts of the signal can be used to derive the distributed temperature profile since these parts represent the whole extent of the sensing fibre owing to the lack of spatial extent of the coil.

Abstract: Methods and apparatus for distributed temperature sensing (DTS) along a single mode or multimode optical waveguide or fiber include a calibration of initial Brillouin-based DTS measurements using Raman-based DTS measurements to enable accurate subsequent Brillouin-based DTS measurements. Such calibration may occur while the fiber is deployed in the environment in which temperature is to be sensed and thereby corrects influences on Brillouin scattered light from stress or strain along the fiber. Further, calibration may utilize one or more discrete temperature sensors to correct errors in one or both of the Brillouin-based DTS measurements and the Raman-based DTS measurements.

Abstract: The temperature measuring device of the present invention comprises: a light source for outputting light; an optical fiber to which light outputted by the light source is inputted and from which Brillouin scattered light is outputted; a detection unit for detecting a spectrum of the Brillouin scattered light; a judgment unit for judging whether or not a frequency shift of the spectrum of the Brillouin scattered light detected by the detection unit belongs to a specific region in which the rate of change of the frequency shift with respect to the temperature of the optical fiber is smaller than a predetermined value; and an analysis unit for, when the judgment unit judges that the frequency shift does not belong to the specific region, analyzing the temperature in use of the frequency shift, and for, when the judgment unit judges that the frequency shift belongs to the specific region, not performing analysis, or analyzing the temperature in use of at least the linewidth of the spectrum of the Brillouin scatte