Abstract: A remote temperature measurement system for a gas turbine engine includes an optical emitter/receiver in communication with the control system and a probe system embedded within a component of the gas turbine engine, the probe system within a line-of-sight of the optical emitter/receiver, the control system operable to determine a local temperature of the component in response to optical communication with the probe system.

Abstract: A method and apparatus for calibration non-contact temperature sensors within a process chamber are described herein. The calibration of the non-contact temperature sensors includes the utilization of a band edge detector to determine the band edge absorption wavelength of a substrate. The band edge detector is configured to measure the intensity of a range of wavelengths and determines the actual temperature of a substrate based off the band edge absorption wavelength and the material of the substrate. The calibration method is automated and does not require human intervention or disassembly of a process chamber for each calibration.

Abstract: A method and an apparatus for determining the heating state of an optical element in a microlithographic optical system involves at least one contactless sensor which is based on the reception of electromagnetic radiation from the optical element. The radiation range captured by the sensor is varied for the purposes of ascertaining a temperature distribution in the optical element.

Abstract: A measurement system is provided for predicting a future status of a refractory lining that is lined over an inner surface of an outer wall of a manufacturing vessel and exposed to an operational cycle during which the refractory lining is exposed to a high-temperature environment for producing a non-metal and the produced non-metal. The system includes one or more laser scanners and a processor. The laser scanners are configured to conduct one or more pre-operational laser scans of the refractory lining prior to the operational cycle to collect data related to pre-operational cycle structural conditions, and one or more post-operational laser scans of the refractory lining after the operational cycle to collect data related to post-operational cycle structural conditions of the refractory lining. The processor is configured to predict future status of the refractory lining after subsequent operational cycles based on the determined exposure impact of the operational cycle.

Abstract: Provided are embodiments including a system for performing aircraft overheat detection using fiber optic monitoring of light reflectance changing temperature strips. Embodiments also include a sensing strip configured to detect a temperature of an object, a controller configured to monitor the sensing strip, and a fiber optic cable configured to transmit or receive a light signal to the sensing strip, wherein the fiber optic cable is operably coupled to the sensing strip and the controller. Embodiments also include a method for operating an aircraft overheat detection system.

Abstract: A remote monitoring system can include a plurality of infrared cables, where each of the infrared cables can have a respective first opening at a first end of the cable and a respective second opening at a second end of the infrared cable that is opposite the first end. The infrared cables can be configured to conduct infrared light emitted from a respective one of a plurality of monitored locations into the respective first opening to exit at the respective second opening. An infrared camera including an infrared sensor array can be optically coupled to each of the second openings of the plurality of infrared cables.

Abstract: A thin sensor film that is capable of indicating temperature and an associated sensor readout kit that illuminates the sensor film and detects the return fluorescence for analysis to determine temperature. The sensor film may be detached and reattached in order to be reused. The initial design achieves high sensitivity and accuracy in the range of interest to biologistics and can potentially address temperatures ranging from ?200 to 300° C. A variation allows for the use of optical fibers for measurements of surfaces inside enclosures.

Abstract: Examples of an integrated active fiber optic temperature measuring device are disclosed. The integrated temperature measuring device comprises a fiber optic probe and an optoelectronic circuitry integrated into a single device which is then individually calibrated. The fiber optic probe has a fiber bundle with an active material at the tip of the probe. The optoelectronic circuitry is connected to the fiber optic probe. The optoelectronic circuitry includes a light source configured to provide an excitation light to the active material, a detector to detect the emitted light, a processing unit configured to determine a temperature based on a change in an emission intensity at a single wavelength range or the change in intensity ratio of two or more wavelength ranges, a lifetime decay, or a shift in emission wavelength peak of the emitted light, and a calibration means configured to calibrate the integrated active fiber optic temperature sensor.

Abstract: An apparatus for accurate measurement of surface and sub-surface temperatures of an object from a distance without contacting the object is provided. Illustrative embodiments provide for simultaneous measurement of thermal emission and emissivity in the mm-wave regime thereby enabling real-time non-contact measurement of emissivity. Corrected temperatures for the object which may be used for calibration of infrared thermographic cameras are determined from the measurement of emissivity.

Abstract: A measurement system is provided for predicting a future status of a refractory lining that is lined over an inner surface of an outer wall of a metallurgical vessel and exposed to a heat during which the refractory lining is exposed to molten metal. The system includes one or more laser scanners and a processor. The laser scanners are configured to conduct a plurality of laser scans of the refractory lining when the metallurgical vessel is empty. At least one of the laser scanners is configured to laser scan the refractory lining prior to the heat to collect data related to pre-heat structural conditions of the refractory lining. At least one of the laser scanners is configured to laser scan the refractory lining after the heat to collect data related to post-heat structural conditions of the refractory lining. The processor is configured to predict the future status of the lining.

Abstract: In one embodiment, a temperature sensor includes an optical waveguide having a distal tip and a thermochromic sensing element mounted to the distal tip of the optical waveguide, wherein light transmitted through the optical waveguide to the distal tip is reflected back from the thermochromic sensing element and wherein the reflected light provides an indication of a local temperature at a location of the thermochromic sensing element.

Abstract: A system includes a thermographic temperature sensor that may measure a temperature of a fluid. The thermographic temperature sensor includes a probe, an optical source coupled to the probe, and a detector coupled to the probe. The system also includes a housing of the probe; and a light pipe of the probe disposed within the housing and including a thermographic phosphor that may phosphoresce in response to absorbing light from the optical source. The phosphorescence by the thermographic phosphor is representative of a temperature of the fluid within a flow path of the fluid, and the detector may detect the phosphorescence by the thermographic phosphor.

Abstract: A thermographic temperature sensor includes a probe having a housing and a light pipe disposed within the housing. The light pipe includes a thermographic phosphor that may phosphoresce in response to absorbing light. The phosphorescence by the thermographic phosphor is representative of a temperature of a fluid in contact with the probe, and a surface area of the light pipe is not in contact with an inner surface of the housing.

Abstract: A device for measuring temperature of a turbine wheel in a turbocharger includes: a guide that passes infrared ray generated from the turbine wheel and includes a coolant path; a protection unit that protects an optical head which senses the infrared ray; and a signal processing unit that measures a temperature of the turbine wheel by processing a signal corresponding to the sensed infrared ray.

Abstract: A method for designing cutting conditions for cutting a workpiece with a cutting tool uses design parameters, including a feed speed, an axial direction cutting amount, a radial direction cutting amount, and a cutting speed of/by the cutting tool. A deflection amount of the cutting tool is calculated from the design parameters. Then a “chattering vibration” occurs or not in the cutting tool is determined. Depending on the determination result, a maximum cutting thickness of the workpiece is calculated. Then a cutting temperature of the cutting tool is calculated. Then whether a tool life of the cutting tool is satisfied or not is determined. Depending on the determination result, a cutting efficiency of the cutting tool is calculated and compared with data of a cutting efficiency stored in advance. When the calculated cutting efficiency is a maximum value among the data, the design parameters are used as the cutting conditions.

Abstract: The subject matter of the invention is a collective remote signaling device for a plurality of serially-arranged devices, wherein each of the devices has an optical signaling unit, with the devices being arranged on a mounting rail, wherein the collective remote signaling device (FM) is likewise arranged on the mounting rail, with the collective remote signaling device having an optical sensor, wherein the optical sensor is connected to the optical signaling units of the devices via an optical waveguide, wherein a state which is displayed by means of one of the optical signaling units at one of the devices is relayed via the optical waveguide to the optical sensor, and is detected in the collective remote signaling device and signaled, with the collective remote signaling device having an optical transmitter, with the optical transmitter being connected to the optical signaling units of the devices via the optical waveguide and light is provided at least for a time to the optical signaling units, whereupon th

Abstract: An optical fiber network test device comprising an actuator that is manually operable, without manual handling of optical fibers, firstly to direct light from a light path of the optical network so that test equipment associated with the network can be operated to test the quality of the said light path, and secondly to return the light path to its previous state after completion of the test.

Abstract: Disclosed herein are representative embodiments of methods, apparatus, and systems for determining the temperature of an object using an optical pyrometer. Certain embodiments of the disclosed technology allow for making optical temperature measurements that are independent of the surface emissivity of the object being sensed. In one of the exemplary embodiments disclosed herein, a plurality of spectral radiance measurements at a plurality of wavelengths is received from a surface of an object being measured. The plurality of the spectral radiance measurements is fit to a scaled version of a black body curve, the fitting comprising determining a temperature of the scaled version of the black body curve. The temperature is then output. The present disclosure is not to be construed as limiting and is instead directed toward all novel and nonobvious features and aspects of the various disclosed embodiments, alone or in various combinations and subcombinations with one another.

Abstract: The subject matter of this specification can be embodied in, among other things, a system for removably attaching an optical fiber sensor loop onto a tubular member, which includes an optical fiber sensor loop having a continuous optical fiber positioned arranged in a plurality of loops, each of said loops having a first end turn and a second end turn, a first and a second turn guide each including a plurality of turn grooves increasing outwardly in increasing radii, each of said turn grooves configured to receive an end turn portion of the optical fiber, a first and a second supporting wedge each having a planar first surface configured to receive a turn guide and a curved second surface configured to be received on the tubular member, and a connector configured to couple the first mounting wedge to the second mounting wedge.

Abstract: Thermometer comprising an organic-inorganic matrix which comprises tris complex (?-diketonate) of two different cations of lanthanide elements. In addition, the invention also relates to the matrix, methods for preparing it and methods of using a thermometer to measure absolute temperatures.

Abstract: Calibration of optical time domain reflectometry optical loss measurement in optical fibers having potentially dissimilar light backscattering properties is disclosed. For example, an optical time domain reflectometer (OTDR) can be employed to perform a single-ended optical loss measurement on an optical fiber before and after joinder (e.g., a splice) to determine the efficiency of the joinder. The individual optical fibers provided in a joined optical fiber may have dissimilar backscatter light collection efficiencies resulting in an erroneous OTDR optical loss measurement, because an OTDR assumes the backscatter light collection efficiency of the joined optical fiber is identical before and after joinder. An OTDR calibration factor is first determined before an OTDR optical loss measurement of the joined optical fiber is made. The OTDR calibration factor is used to correct any error in an OTDR optical loss measurement of the joined optical fiber.

Abstract: Scattering parameters of a test fixture having a first port and a second port are measured by providing a test instrument; outputting a one-port reflection test signal from the test instrument to the first port with the second port terminated in a reflective termination having a known reflection coefficient, and receiving at the test instrument a one-port reflection measurement signal from the first port; subjecting the one-port reflection measurement signal to first time gating to generate a first time-gated measurement signal, the first time gating using a first gating function temporally disposed about the first port; subjecting the one-port reflection measurement signal to second time gating to generate a second time-gated measurement signal, the second time gating using a second gating function temporally disposed about the termination; and deriving the scattering parameters from the first time-gated measurement signal and the second time-gated measurement signal.

Abstract: The present apparatus includes: an intensity ratio calculation unit configured to calculate a first and a second intensity ratios which are ratios of Stokes light intensity to anti-Stokes light intensity obtained when a light pulse is output to a first end and a second end of an optical fiber, respectively; a temperature calculation unit configured to calculate a temperature distribution along the optical fiber based on a reference temperature, the first and the second intensity ratios, and a total length loss ratio, which is a loss ratio of Stokes light to anti-Stokes light with regard to a total length of the optical fiber; and a total length loss ratio calculation unit configured to calculate the total length loss ratio based on the first and the second intensity ratios with regard to a location in a predetermined section close to both ends of the optical fiber whose temperature is kept constant.

Abstract: An optical absorption gas analyzer is provided for determining the concentration of a target gas in a sample, comprising: a chamber for containing the sample in use; an optopair, comprising a light emitting diode (LED) arranged to emit radiation into the chamber and a photovoltaic radiation detector arranged to detect radiation transmitted through the chamber from the LED and to output a corresponding detection signal SS; a temperature sensor arranged in thermal contact with the LED and the photovoltaic radiation detector, and to output a temperature signal T representing the temperature of the optopair; a memory having stored therein data representative of the baseline detection signal ST output by the optopair in the absence of the target gas as a function of the temperature of the optopair across a range of temperatures; and a processor adapted to generate a differential detection signal SA indicative of the concentration of target gas in the sample by retrieving from the memory the baseline detection sign

Abstract: A milliwave melter monitoring system is presented that has a waveguide with a portion capable of contacting a molten material in a melter for use in measuring one or more properties of the molten material in a furnace under extreme environments. A receiver is configured for use in obtaining signals from the melt/material transmitted to appropriate electronics through the waveguide. The receiver is configured for receiving signals from the waveguide when contacting the molten material for use in determining the viscosity of the molten material. Other embodiments exist in which the temperature, emissivity, viscosity and other properties of the molten material are measured.

Abstract: A testing device equipped with: a microchip having a receiver for a test fluid, a discharge lamp which emits light into the microchip test fluid receiver, a light source housing in which the discharge lamp is located, and an arithmetic calculation mechanism, which calculates the concentration of the component to be detected, based on the intensity of the light emitted from the test fluid container unit. To reduce the size of the device and to shield the arithmetic calculation mechanism from electromagnetic waves generated around the light source, the light source housing is equipped with shielding connected to the ground on the outside of the light source housing made of insulating material. The light source housing is positioned within an enclosure of the testing device holding the microchip and containing the arithmetic calculation mechanism, analysis output device(s), and other components of the testing device.

Abstract: A calorimeter is provided for measuring a quantity of heat. The calorimeter has a liquid constrained so as to allow expansion of the liquid solely in one dimension along a single axis such that liquid expansion may be measured on the basis of light impinging along the single axis of liquid expansion by means of a non-contact displacement transducer. Interferometric optical means for remote measurement of multiple microcalorimeters permits parallel monitoring of multiple chemical reactions and the performance of parallel biochemical assays.

Abstract: Methods and systems are provided for determining the density and/or temperature of a fluid based on a reflection of optical energy directed at the fluid.

Abstract: Disclosed is a method of forming an optical monitoring or transmitting light guide and a resulting apparatus that begins by bonding a bundle of optical fibers together using an epoxy and polishing the distal end of the bundle of optical fibers to create an optical aperture. The ratio of fiber size to binder particulate size of the epoxy used in the bonding process is sufficient to maintain the integrity of the bundle of optical fibers during the polishing of the distal end. The method positions the bundle of optical fibers into a protective sheath and a connector. The coefficient of thermal expansion of the epoxy used in the bonding process matches that of the connector. Once assembled, the invention positions the connector through the opening in the surface of a device, such that the distal end of the bundle of optical fibers is either recessed in, substantially flush with, or extends from the surface of the device through which the connector extends, depending on field-of-view requirements.

Abstract: A method is provided for measuring a temperature of a molten metal bath by an optical fiber surrounded by a cover. The optical fiber is immersed in the molten bath, and the radiation absorbed by the optical fiber in the molten bath is fed to a detector, wherein the optical fiber is heated when immersed in the molten bath. The heating curve of the optical fiber has at least one point P(t0, T0), wherein the increase ?T1 in the temperature T of the optical fiber over the time ?t in a first time interval t0??t up to the temperature T0 is smaller than the increase ?T2 in the temperature of the optical fiber over the time ?t in an immediately following second time interval t0+?t.

Abstract: An apparatus for continuously monitoring a photopolymerization reaction in real time by optical pyrometry includes a housing having a chamber; a sample mount that may be disposed within the chamber; a light source for supplying light to induce a photopolymerization reaction in a monomer sample disposed on the sample mount; and an optical pyrometer that may be attached to the housing for measuring temperature of the monomer sample. The temperature of the sample with respect to time is used to monitor progress of the reaction. Another apparatus for monitoring a photopolymerization reaction combines optical pyrometry and infrared spectroscopy. The apparatus includes a sample mount disposed in a beam of an infrared spectrometer a light source for supplying light to induce a photopolymerization reaction in a monomer sample disposed on the sample mount and an optical pyrometer for measuring temperature of the monomer sample.

Abstract: A method and apparatus for sensing temperature using optical fiber is provided. In one embodiment, a method for sensing temperature using optical fiber includes launching a polarized optical signal having sufficient intensity to produce Brillouin scattering of the signal into a polarization maintaining optical fiber, receiving a first signal reflected from the launched signal, receiving a second signal reflected from the launched signal; and resolving a metric indicative of temperature from the first and second received signals. The method is particularly useful for sensing temperature in hazardous locations such as down hole gas and oil field applications or other applications where minimization of strain effects to signal transmission is desired.

Abstract: A method and apparatus for sensing temperature using optical fiber is provided. In one embodiment, a method for sensing temperature using optical fiber includes launching a polarized optical signal having sufficient intensity to produce Brillouin scattering of the signal into a polarization maintaining optical fiber, receiving a first signal reflected from the launched signal, receiving a second signal reflected from the launched signal; and resolving a metric indicative of temperature from the first and second received signals. The method is particularly useful for sensing temperature in hazardous locations such as down hole gas and oil field applications or other applications where minimization of strain effects to signal transmission is desired.

Abstract: A lamp house storing a plurality of flash lamps and a chamber storing and holding a semiconductor wafer are fitted to each other in an openable/closable manner. The lamp house and the chamber are fixed to a closed state with male screws. In order to process a semiconductor wafer, a shutter plate is drawn out to open an irradiation window. In this state, the shutter plate shields a space located above the male screws so that the male screws cannot be detached for opening the lamp house and the chamber. In order to open the lamp house and the chamber, the shutter plate must be inserted for shielding the irradiation window while opening the space located above the male screws. Thus, a thermal processing apparatus capable of preventing the lamps from breaking during maintenance thereof is provided.

Abstract: A method and apparatus is disclosed for measuring the flow of fluid in the conduit, giving the example of oil in a well bore (12). A heat exchanger such as a cooling station (66) is placed in the well bore (12) and caused to create a slug of cooled oil whose passage, through the well (12) can be monitored by a temperature sensor in the form of a continuous fiber optic loop (62). Knowledge of the movement of the cooled slug of oil and of the free cross-section of the conduit (54) wherein the oil is flowing permits the volume flow-rate of oil to be calculated. Cooling stations (66) are cooled by Joule-Thompson cooling employing high pressure nitrogen gas. Cooling stations (66) may be placed at plural locations within the well bore (12) to monitor individual flows (68) from multiple flow sources.

Abstract: A fiber optic cable is used as a distributed temperature sensing (DTS) transducer for temperature profile measurements in a protective underground duct in which a high voltage (HV) cable has already been laid. The sensing cable is not incorporated into the power cable itself, and in some installations does not have direct physical contact with the HV cable. The sensing cable is installed externally (along side) of the HV power cable, either in direct surface contact with the HV cable, or alternatively, the fiber optic sensing cable is installed in a small diameter guide tube that is placed in the upper annulus between the HV cable and the protective duct. The sensing fiber and one or more guide tubes are installed in a loose bundle at least in part by fluid drag forces (blowing with pressurized air) using conventional cable launching equipment.

Abstract: Use of an optical fibre for the direct receipt of heat radiation for transmission to a remote pyrometer is enabled by the provision of an apertured, contaminant free compartment in the component being heated, and aligning the heat receiving end of the optical fibre with the aperture so as to receive radiated heat from within the compartment.

Abstract: An optical time-domain reflectometer (OTDR) launches pulses of light into a link or a system of multiplexed links and records the waveform of pulses reflected by the seals in the link(s). If a seal is opened, the link of cables will become a discontinuous transmitter of the light pulses and the OTDR can immediately detect that a seal has been opened. By analyzing the waveform, the OTDR can also quickly determine which seal(s) were opened. In this way the invention functions as a system of active seals. The invention is intended for applications that require long-term surveillance of a large number of closures. It provides immediate tamper detection, allows for periodic access to secured closures, and can be configured for many different distributions of closures. It can monitor closures in indoor and outdoor locations and it can monitor containers or groups of containers located many kilometers apart.

Abstract: A gas-insulated cable includes a plurality of sections separated by sealed partitions, each section including a cylindrical steel case, a cylindrical aluminum screen coaxial with and inside the case and three conductors. A monitoring device includes, between the case and the screen, optical fibers equal in number to the number of sections of the cable and extending from one end to the other of the cable, each of the sections being monitored by a single fiber. The monitoring device further includes at least one optical internal arc detector inserted in series into each fiber in the corresponding monitored section, at each end of the device, a device for detecting light conveyed by the optical fibers, and at least one optical threshold temperature detector inserted in series into each fiber in the corresponding monitored section.

Abstract: A fiber optic linked flame sensor for continuous optical monitoring of the combustion process within the combustion chamber of a gas turbine engine. The system includes a high temperature optical probe, a fiber optic cable, and electro-optics module. The high temperature probe is mounted on the engine skin and sighted in a manner so as to view the combustion process taking place at its origin just aft to the fuel nozzle. The appropriately constructed fiber optic cable connects the high temperature probe with the electro-optics module. The radiation transmitted via the fiber optic cable is then received by an ultraviolet photodiode located in the electro-optics module and coupled with appropriate electronics.

Abstract: A temperature distribution measuring apparatus and related method uses optical time domain reflectometry to determine temperature distribution along an optical fiber. A light pulse enters the fiber at one end, and backscattered light at each of various points in the optical fiber has a Raman spectrum which contains temperature information. An impulse response to the Raman spectra of backscattered light is produced using a transformation to provide a temperature distribution along the optical fiber. An impulse response on the anti-Stokes component and an impulse response of the Stokes component of the Raman spectrum are each produced, and the ratio between them indicates temperature distribution. Each impulse response is obtained by performing deconvolution on the Stokes component and the anti-Stokes component using an inverse matrix of measured incident light, the inverse matrix being obtained by an iteration method with an optimum number of iterations.

Abstract: Wall temperatures of a reactor vessel are monitored by arranging an optical fibre in thermal contact with the wall and employing an optical time domain reflectometry system to monitor the respective temperatures at different points along the fibre. Such a monitoring method can be cheaper and more reliable than comparable prior art methods. An alarm may be triggered automatically when hot spots are detected.

Abstract: A temperature sensor having a light fiber connecting a light source and a reflectometer. Temperature measurement zones are formed by sensing elements made of shape-memory alloy. The elements exert a stress on the fiber when they are subjected to an increase in temperature due to their memorized state. The change in temperature is detected by the reflectometer.

Abstract: In a temperature distribution measuring apparatus which projects pulsed-light into an optical fiber, measures Raman spectrum of backscattered light occurred in the optical fiber, and obtains a temperature distribution along the optical fiber, to improve the positional resolution, it is necessary to narrow the width of the incident pulsed-light. A response of the backscattered light to a pulsed-light of a finite width is considered to be convolution and deconvolution of the measured value of the backscattered light is performed to obtain an impulse response. Deconvolution which is an inverse transform requires a waveform of the incident light and which is previously measured. When deconvolution is performed by using an inverse matrix of the incident light, it is necessary to calculate the inverse matrix by means of an iteration method.

Abstract: An apparatus for measuring a temperature distribution along an optical fiber, comprises a light source for inputting pulsed-light into the optical fiber, an optical filter for receiving backward Raman-scattered light from the optical fiber and extracting anti-Stokes' light and Stokes' light, an optical attenuator for attenuating the intensity of the Stokes' light extracted by the optical filter, first and second signal paths each of which includes a light-receiving element and an analog-to-digital converter, a signal processor for calculating a temperature distribution along the optical fiber on the basis of the first and second signal paths, and an optical switch having a first input port for receiving the anti-Stokes' light, a second input port for receiving the Stokes' light, a first output port, and a second output port, the optical switch transmitting the anti-Stokes' light and the Stokes' light to the first output port and the second output port in a first switching position and transmitting the Stokes'

Abstract: An optical sensor system includes a housing having an open end; first and second windows situated in the housing; a fastener for situating the first window closer to the open end than the second window and permitting an air exchange between a sensing region and the second window; a hermetic seal between the second window and the housing; and an optical sensor situated between the second window and a wall of the housing such that the air exchange does not occur inside the optical sensor. The first and second windows can include materials selected from the group consisting of sapphire, quartz, and glass; the optical sensor to be protected can include silicon carbide; and the sensing region can include a combustion region.

Abstract: Optical time domain reflectometry methods and apparatus are proposed in which the back-scattered optical radiation used to produce output signals is restricted to that resulting from Rayleigh scattering of light launched into a fiber 2 at a first wavelength and that in an anti-Stokes spectral band resulting from Raman or Brillouin scattering of optical radiation at the first wavelength. A first set of output signals produced in dependence upon the anti-Stokes back-scatter may be normalized to the geometric mean of a second set of output signals, produced in dependence upon the Rayleigh back-scatter at the first wavelength, and a third set of output signals, produced in dependence upon Rayleigh back-scatter resulting from light launched into the fiber at the anti-Stokes wavelength.

Abstract: An apparatus and method for measuring a temperature of a high temperature liquid contained in a furnace. An optical fiber covered with a metallic tube is inserted through a passageway inside a nozzle arranged on a furnace wall of the furnace. The nozzle communicates with an interior of the furnace containing the liquid, and gas is supplied into the passageway inside the nozzle to prevent the nozzle from clogging. The metal-covered optical fiber is fed through the passageway inside the nozzle into the liquid such that spectral light radiated from the liquid enters a tip of the metal-covered optical fiber and is propagated therealong. The temperature of the liquid is determined by a radiation thermometer, coupled to the metal-covered optical fiber, based on the spectral light propagated along the metal-covered optical fiber.

Abstract: An optical method for measuring the temperature of a substrate material with a temperature dependent bandgap. The substrate is illuminated with a broad spectrum lamp and the bandgap is determined from the spectrum of the diffusely scattered light. The spectrum of the light from the lamp is sufficiently broad that it covers the spectral range above and below the bandgap of the substrate. Wavelengths corresponding to photon energies less than the bandgap of the substrate are transmitted through the substrate and are reflected from the back surface of the substrate as well as from the front surface while the wavelengths corresponding to photon energies larger than the bandgap are reflected only from the front surface. If the front surface is polished the front surface reflection will be specular while if the back surface is rough the reflection from the back surface will be non-specular. The back surface reflection is detected with a detector in a non-specular location.

Abstract: A birefringent active fiber laser sensor includes one or more fiber lasers 12, 14, 16, each having a pair of Bragg gratings 18, 20, embedded in a fiber 10 and excited by a common pump light 30. At least one of the lasers 12, 14, 16 has a laser cavity wit a predetermined birefrigence and a lasing light at a first lasing frequency along a first polarization axis, and at a second fusing frequency along a second polarization axis. A difference frequency between the first and the second lasing frequencies is related to the magnitude of the birefringence, and the birefringence varies in response to a perturbation. Output light 104 from each of the lasers 12,14,16 is fed to a defraction grating 106 which splits the beam 104 into different wavelength groups, each group having the two lasing frequencies and polarizations of a given laser.