Abstract: A temperature probe includes a sensor material optically communicating with a waveguide, and a sheath having a sheath coefficient of thermal expansion substantially matched to a thermal expansion coefficient of the waveguide. The waveguide has first and second ends secured proximate corresponding sheath ends. In another aspect of the invention, waveguide ends are secured near the sheath ends, the sheath is bent at one or more locations so that it is noncylindrical, and a midsection of the waveguide is loosely held within the bent sheath. In still another aspect of the invention, a metallic tube with the sensor material disposed therein is secured to the waveguide by direct attachment to a metallic coating on the waveguide.

Abstract: Simultaneous measurement of neutron flux and temperature is provided by a single sensor which includes a phosphor mixture having two principal constituents. The first constituent is a neutron sensitive 6LiF and the second is a rare-earth activated Y203 thermophosphor. The mixture is coated on the end of a fiber optic, while the opposite end of the fiber optic is coupled to a light detector. The detected light scintillations are quantified for neutron flux determination, and the decay is measured for temperature determination.

Abstract: A luminescence-based integrated optical and electronic system for measuring temperature or some other parameter from the decay time of a luminescent sensor is disclosed. A high bandwidth, low noise amplifier applies a detected decaying luminescent signal to a digital system that acquires that signal and processes it in order to determine its decay time characteristics that are related to temperature or another parameter being measured. The digital signal processing includes use of a digital curve-fitting technique. A preferred luminescent material for temperature measurement is a chromium-doped yttrium gallium garnet material. The entire optical and electronic portions of the measuring system can be accommodated on a small single circuit card.

Abstract: An apparatus and method for remotely measuring emissivity and hence temperature of a surface of an object. The apparatus includes a detector having a radiation receptor for measuring infra-red radiation, an integrating cavity surrounding the receptor for receiving radiation from a surface facing the cavity and delivering the radiation to the receptor, at least two sources of infra-red containing radiation (e.g. light from an incandescent lamp) within the integrating cavity positioned to produce separate beams of the radiation which strike the surface at different angles suitable for reflection to the receptor, and a processor for determining the temperature of the surface from the radiation measured by the detecting means. The use of at least two mutually angled radiation beams compensates for surface anisotropy of the surface whose temperature is to be measured.

Abstract: The monitoring of energy radiating from a heated material, such as a hot melt adhesive, dispensed onto a substrate may be accomplished by an infrared sensor. The wand of the infrared sensor is located downstream of the dispensed material for receiving the radiant energy. The wand is provided with internal air for cooling and for providing laminar air flow in the vicinity of the lens to prevent the accumulation of airborne contaminants on the lens. The wand is also provided with a light aiming device.

Abstract: A concentration correcting apparatus comprising a correction coefficient calculating means and a correcting means is shown and described. The correction coefficient calculating means calculates a correction coefficient for correcting the concentration of the material when the actual density of the medium at the measurement of the material is calculated in terms of the density of the medium under the reference temperature and pressure, from the results of the temperature measuring means and the pressure measuring means. The correcting means corrects the results of the material measuring means to a concentration under the reference temperature and pressure on the basis of the correction coefficient.

Abstract: Thermal, optical, physical and chemical characteristics of a substrate (11) surface are determined with non-contact optical techniques that include illuminating (23) the surface with radiation having a ripple intensity characteristic (51), and then measuring the combined intensities (53) of that radiation after modification by the substrate surface and radiation emitted from the surface. Precise determinations of emissivity, reflectivity, temperature, changing surface composition, the existence of any layer formed on the surface and its thickness are all possible from this measurement. They may be made in situ and substantially in real time, thus allowing the measurement to control (39, 41) various processes of treating a substrate surface. This has significant applicability to semiconductor wafer processing and metal processing.

Abstract: A temperature abnormality detecting structure for a fluid pipe detects a temperature abnormality location by laying an optical fiber serving as a temperature detecting portion of a Ramam scattering optical fiber distribution type temperature sensor along a fluid pipe. The fluid pipe is divided into a plurality of sections in the longitudinal direction, independent optical fibers are laid along the fluid pipe in the respective sections. A portion of the optical fiber laid along one of the adjacent sections is superposed to be laid on a portion of the optical fiber laid along the other of the adjacent sections in the vicinity of each of the respective boundaries of the sections.

Abstract: A method for monitoring temperature in a turbine component includes detecting a change in photoconduction properties in a fiber-optical cable disposed inside a turbine component, being caused by a temperature change in the turbine component. An apparatus for monitoring temperature in a turbine component includes a fiber-optical cable disposed in the interior of a turbine component, and a device for detecting a change in photoconduction properties in the fiber-optical cable being caused by a temperature change in the turbine component.

Abstract: Optical sensors for physical parameters use a parameter-dependent relative distribution of the intensity of interrogating light of wavelengths .lambda..sub.1 between two light-guiding regions of a light-guiding probe. The relative distribution can be determined by a plurality of means including the spatial separation of the lights carried by the two light-guiding regions, and/or the conversion of one of the lights into light of wavelengths .lambda..sub.2 different and easily separable from light of wavelength .lambda..sub.1. The sensors can be adapted to measure diverse physical parameters, including but not limited to temperature, and to measure infrared radiation by measuring its heating effect on the sensing probes.

Abstract: A temperature measuring system that utilizes an electronic control unit and a rod made of a first material with a first thermal coefficient of expansion, the rod being attached at one end within a tubular device made of a material having a second coefficient of expansion. A reflecting surface is on the outer end of the rod of first material. At least one optical fiber is associated with the tubular member and is located so as to create a gap between the optical fiber and the reflecting surface. The first and second materials are chosen based upon their respective coefficients of thermal expansion such that a change in temperature of both materials will cause the length of the gap to either increase or decrease, thereby causing a change in the amount of light that is reflected and detected by the optical fibers.

Abstract: An optical switch (14) is disposed with in a measuring section (3) and connected to a base portion of an optical fiber (2). The optical switch (14) includes a pair of adjusting optical fibers (15, 16) having lengths different from each other by a half of a distance resolution, and the optical switch (14) is driven by a pulse driving circuit (4) in synchronism with a semiconductor laser (5) which emits a light pulse. When the optical switch (14) is driven, either one of the adjusting optical fibers (15, 16) is selectively connected to the optical fiber (2) so that two detection routes having different lengths are formed. The temperature distribution measurement values respectively for the two detection routes and having a phase displaced from each other corresponding to the half of the distance resolution are calculated in a high speed averaging processing unit (11), and then a temperature distribution value along the optical fiber (2) is calculated in a data processing unit (12).

Abstract: An optical fiber temperature sensor including an optical fiber (1) which has a mirror (3) at its end, and which is associated with temperature-sensitive means, means for launching a signal into said fiber and means for receiving the signal reflected by said mirror back along the fiber, said temperature-sensitive means being a section of amplifying optical fiber (10) bonded to said optical fiber (1), cooperating with a light pump source, and doped with a chosen rare-earth element.

Abstract: A high temperature optical probe for an optical gas temperature sensor includes a support, a generally conical hollow tip, and a joint physically interconnecting the support and the tip. The tip includes as an electromagnetic radiation emitter a sapphire-free ceramic selected from the group consisting of silicon carbide and silicon nitride.

Abstract: A temperature sensing system has a signal means which provides a signal representative of a temperature responsive luminescence, where the luminescence has a characteristic time-rate-of-decay. A means for comparison is connected to the signal means and samples the signal during two time intervals, the first interval overlapping the second. The averages of the samples are compared to provide a difference signal representative of the difference between the two measured averages. Control means coupled to the comparison means provide an output representing the temperature as a function of the time-rate-of-decay, by adjusting the overlapping intervals so that the difference signal converges to a preselected limit.

Abstract: A multi-point non-invasive, real-time pyrometry-based temperature sensor (200) for simultaneously sensing semiconductor wafer (22) temperature and compensating for wafer emissivity effects. The pyrometer (200) measures the radiant energy that a heated semiconductor wafer (22) emits and coherent beams of light (224) that the semiconductor wafer (22) reflects. As a result, the sensor (200) generates accurate, high-resolution multi-point measurements of semiconductor wafer (22) temperature during a device fabrication process. The pyrometer (200) includes an infrared laser source (202) that directs coherent light beam (203) into beam splitter (204). From the beam splitter (204), the coherent light beam (203) is split into numerous incident coherent beams (210). Beams (210) travel via optical fiber bundles (218) to the surface of semiconductor wafer (22) within the fabrication reactor (80). Each optical fiber bundle (218) collects reflected coherent light beam and radiant energy from wafer (22).

Abstract: A sensor for use in an optical temperature detector system having a birefringent element made of a single crystal metal oxide plate. A broad band light spectrum is transmitted through a first linear polarizing element to create a linearly polarized wave. The linearly polarized wave on passing through the single crystal metal oxide plate decomposes into first and second orthogonally polarized waves. Propagation of the linearly polarized wave through the birefringent single crystal metal oxide plate introduces a temperature dependent phase shift between the two waves. Thereafter, a second linear polarizer combines the first and second orthogonally polarized waves to create a modulated light spectrum having a fringe pattern, the fringe pattern being a function of the current temperature experienced by said birefringent element.

Abstract: A temperature sensing apparatus and method of measuring the temperature at the bottom of a rotor slot in a rotating rotor using a temperature sensitive phosphor material. The temperature sensitive phosphor material is placed at the bottom of a rotor slot and is excited, as the rotor rotates, by an excitation source located at a location opposite the rotor, the excited radiation being detected at two spaced locations from the excitation source, the two spaced locations being located also opposite the rotor and spaced apart along the direction of the rotor. Then the decay rate of the detected radiation from the phosphor is determined and from this decay rate the temperature at the bottom of the rotor slot.

Abstract: A temperature distribution analyzer is disclosed. In the analyzer, a measuring optical fiber is provided so as to extend through a target region in order to analyze the temperature distribution of the region. A LD pumped solid state laser generates pulse light having high energy and supplies the pulse light to one of the terminal portions of an optical fiber. This causes a stimulated-Raman-scattering phenomenon in the optical fiber whereby Raman-scattered light is obtained from the other terminal portion of the excitation optical fiber. An optical filter selects light having a predetermined wavelength from the Raman-scattered light and outputs the selected light. An optical device introduces the output light of the optical filter to one of the terminal portions of the measuring optical fiber and receives Raman-backscattered light generated in the measuring optical fiber through the same terminal portion. A photodetector converts the Raman-backscattered light to an electrical signal.

Abstract: A relatively simple optical monitoring technique is utilized to measure temperature within a processing chamber. A III-V direct-bandgap semiconductor is optically excited to emit photoluminescence (PL). Spectral resolution of the emitted PL provides a direct measure of the bandgap of the semiconductor. In turn, the temperature of the semiconductor is derived from the bandgap measurement.

Abstract: A temperature sensing system has a signal means which provides a signal representative of a temperature responsive luminescence, where the luminescence has a characteristic time-rate-of-decay. A means for comparison is connected to the signal means and samples the signal during two time intervals, the first interval overlapping the second. The averages of the samples are compared to provide a difference signal representative of the difference between the two measured averages. Control means coupled to the comparison means provide an output representing the temperature as a function of the time-rate-of-decay, by adjusting the overlapping intervals so that the difference signal converges to a preselected limit.

Abstract: It is a problem of pyrometric temperature measuring of melts in a vacuum that the material of the melt will be deposited on mirrors, windows and other optical devices so that the radiation will be screened more and more effectively, the closer it comes to the pyrometer. In order to avoid vapor desposition in the path of radiation, a grating arrangement is provided between the melt and the pyrometer, which focusses the incoming radiation and concentrates it onto the pyrometer. The grating arrangement is partly permeable to the molecules of the melt material. The direct path between the melt and the pyrometer is blocked by a screen. In this way, vapor deposition on the window prefixed to the pyrometer are avoided, while the radiation can reach the pyrometer.

Abstract: High temperature range black body techniques are combined with lower temperature range photoluminescent techniques to provide an optical method and apparatus for measuring temperature over a very wide range. Among the various optical probe configurations disclosed which combine the black body and photoluminescent technologies is an optical temperature measuring probe including an elongated transparent light pipe with a black body cavity and a photoluminescent material adjacent one end of the light pipe. Signal detection and processing can be combined, and temperature measurements made by the photoluminescent technique within an overlap of the two temperature ranges can be used to calibrate measurements made in the higher range by the black body technique.

Abstract: An optical temperature sensor has an outer probe with a sapphire element at its forward end within a stagnation chamber through which hot gas flows and heats a thermally-emissive coating on the element. A lens focusses radiation emitted by the coating onto one end of a fibre-optic cable that extends within the rear of the probe. A gas passage along the probe enables cooling gas to flow from an inlet at the rear end, around the fibre optic cable, lens and through an outlet rearwardly of a transparent thermal barrier which protects the sapphire element from the cooling gas.

Abstract: In an optical fiber laying structure for an electric power cable line trouble occurrence location detecting system for detecting a trouble occurrence location by laying an optical fiber along an electric power cable line, the portion of the optical fiber laid along the cable of one of the two adjacent sections is superposed on the portion of the optical fiber laid along the cable of the other sections in an area in the vicinity of the boundary of the electric power cable line. Thus, if a temperature rise occurs due to a trouble such as a ground-fault in the boundary area, the temperature peak position, i.e., the trouble occurrence location can be detected by the two different optical fibers. Therefore, the trouble occurrence location in the boundary area can be accurately detected.

Abstract: A heat cooking apparatus arranged to cook a food article through heating by projecting microwave energy generated by a magnetron and heat rays produced by an electric heating unit onto the food article placed in a heating chamber, and including a light source for projecting visible light rays onto the food article, a photo-detector for detecting a light amount of the visible light rays reflected by the food article, a temperature sensor for detecting temperature within the heating chamber, and a control unit which monitors variation with time of detection signals from the photo-detector and the temperature sensor during heating of the food article by the electric heating unit and controls to complete the heating of the electric heating unit by judging that the heating is to be terminated when the detection signal of the photo-detector is reduced by a predetermined value from a maximum value, and the detection signal of the temperature sensor is increased by a predetermined value from an initial value.

Abstract: A thermometer for measuring the core temperature of a body by measuring infrared radiation emitted by the tympanic membrane of the ear. The thermometer includes a fiber optic fiber bundle assembly which is inserted into the ear canal to a location adjacent to the tympanic membrane. Infrared radiation is conveyed to a thermopile which converts the radiation to an electrical signal. To assure an accurate signal in changing ambient temperature conditions, circuitry is provided which measures the thermopile resistance (heat) just prior and/or just subsequent to taking a temperature reading and nulling this signal. A disposable sheath is provided to cover the end of the fiber optic assembly inserted into the ear canal to prevent cross contamination between patients. The sheath includes an infrared radiation transparent window over the end of the fiber optic so that there are no openings in the sheath within the ear.

Abstract: A precious metal blackbody radiator fired on a silica or sapphire fiber is disclosed for use in an optical fiber thermometer. The fiber can be coated or uncoated. If a coated fiber is used, the fiber can be a silica or sapphire fiber, protected with an outer metallic coating, such as platinum, which may be electroplated over a thin electrically conductive film coated on the fiber. The blackbody radiator may be mounted on a first end of the fiber, and the fiber may have a second end terminating at a receptor apparatus. The blackbody may comprise semisolid platinum paste placed on a coated or uncoated fiber, dried, and fired over a flame or in a high-temperature furnace. The firing step causes strong adhesion of the blackbody to the fiber.

Abstract: A multi-point non-invasive, real-time pyrometry-based temperature sensor (200) for simultaneously sensing semiconductor wafer (22) temperature and compensating for wafer emissivity effects. The pyrometer (200) measures the radiant energy that a heated semiconductor wafer (22) emits and coherent beams of light (224) that the semiconductor wafer (22) reflects. As a result, the sensor (200) generates accurate, high-resolution multi-point measurements of semiconductor wafer (22) temperature during a device fabrication process. The pyrometer (200) includes an infrared laser source (202) that directs coherent light beam (203) into beam splitter (204). From the beam splitter (204), the coherent light beam (203) is split into numerous incident coherent beams (210). Beams (210) travel via optical fiber bundles (218) to the surface of semiconductor wafer (22) within the fabrication reactor (80). Each optical fiber bundle (218) collects reflected coherent light beam and radiant energy from wafer (22).

Abstract: A non-contact pyrometric technique is provided for measuring the temperature and/or emissivity of an object that is being heated by electromagnetic radiation within the optical range. The measurement is made at short wavelengths for the best results. The measurement may be made at wavelengths within those of the heating optical radiation, and the resulting potential error from detecting heating radiation reflected from the object is avoided by one of two specific techniques. A first technique utilizes a mirror positioned between the heating lamps and the object, the mirror reflecting a narrow wavelength band of radiation in which the optical pyrometer detector operates. The second technique is to independently measure the a.c. ripple of the heating lamp radiation and subtract the background optical noise from the detected object signal in order to determine temperature and emissivity of the object. Both of these techniques can be combined, if desired.

Abstract: A temperature sensor comprising a probe, infrared fibers, super-cooled detors and their associated electronics, and a computer for determining the temperature from the output of the electronics. Photons from a heat source are collected by the infrared fibers and transmitted to the detectors where they are amplified by the electronics. A voltage is then outputted which represents measured temperature. The voltage is sampled by the computer where it is converted to temperature by use of computer algorithms.

Abstract: High temperature range black body techniques are combined with lower temperature range photoluminescent techniques to provide an optical method and apparatus for measuring temperature over a very wide range. Various optical probe configurations are disclosed which combine the black body and photoluminescent technologies. Signal detection and processing can be combined, and temperature measurements made by the photoluminescent technique within an overlap of the two temperature ranges can be used to calibrate measurements made in the higher range by the black body technique.

Abstract: It is a problem of pyrometric temperature measuring of melts in a vacuum that the material of the melt will be deposited on mirrors, windows and other optical devices so that the radiation will be screened more and more effectively, the closer it comes to the pyrometer. In order to avoid vapor deposition in the path of radiation, a grating arrangement is provided between the melt and the pyrometer, which focusses the incoming radiation and concentrates it onto the pyrometer. The grating arrangement is partly permeable to the molecules of the melt material. The direct path between the melt and the pyrometer is blocked by a screen. In this way, vapor deposition on the window prefixed to the pyrometer are avoided, while the radiation can reach the pyrometer.

Abstract: A temperature-measuring method comprises inputing laser pulses into an optical fiber to be measured and measuring temperature distribution in the fiber from the ratio of the amplitudes and the delay time of Stokes light and anti-Stokes light contained in the return beam from the optical fiber, wherein the temperature distribution is measured by using equations: ##EQU1## where T(x) is temperature to be measured, .THETA. is the reference temperature, R' (T) is the relative ratio of amplitude at the measuring point, R' (.THETA.) is the relative ratio of amplitude at the reference temperature point, k is Boltzmann's constant, h is Planck's constant, c is velocity of light, .nu. is Raman shift, .alpha. is distance, wherein the attenuation difference .alpha. is represented by a function .alpha.{T(.tau.)} dependent on temperature T(.tau.) at the measuring point .tau., and the exponential function in which the exponential part is represented by a value obtained by integrating the function .alpha.{T(.tau.

Abstract: A device for the measurement of a temperature in a relatively low range having the lower limit of below 100.degree. C. is proposed. The device is suitably used for measuring a temperature of a substrate 4 during a sputtering treatment in a vacuum environment. Infrared rays radiated from the substrate 4 in a vacuum chamber 1 are collected by an optical lens 13 mounted in a freely movable probe 10 via a mirror (15) provided in a hood 14 attached to a front end of the probe (10) for deflecting the incident rays to the lens 13. The collected rays are led outside the chamber 1 to a sensor through a fluoride fiber 8 optically connected to the lens 13. The fiber 8 is enveloped in an air-tight manner within a metal bellows 9.

Abstract: The invention is drawn to methods and devices which allow the simultaneous optical measurement of temperature and another physical parameter using a single probe, a single interrogating light source and a single photodetector. The invention also allows the use of a single probe for meausring temperature in two independent physical modes, using a single interrogating light source and a single photodetector. The single probe includes a photoluminescent material having luminescent centers which when excited with transient interrogating light of a wavelength within a predetermined spectral range emit luminescence light from two excited electronic energy levels, one of them being higher than the other and having a higher rate of luminescence decay than the other level, and wherein the relative intensities of the luminescence light emitted from each of the two excited energy levels vary as a function of the probe temperature.

Abstract: A temperature sensor comprising a hollow shield including a cone shaped tip portion and a substantially cylindrical portion. The cylindrical portion surrounds a high temperature collection rod (e.g., a lightpipe or optical fiber). The collection rod is arranged to collect radiant energy from the cone shaped tip portion and transmit the radiation to a fiber optic cable attached to the opposite end of the collecting rod.

Abstract: A temperature-measuring method which comprises inputting laser pulses into an optical fiber to be measured and measuring the temperature distribution in the fiber from the ratio of the amplitudes and the delay time of the Stokes light and the anti-Stokes light contained in the return beam from the optical fiber, wherein the temperature distribution is measured by using an equation: ##EQU1## where T(x) is the temperature to be measured, .THETA. is the reference temperature, R'(T) is the relative ratio of amplitude to the measuring point, R'(.THETA.) is the relative ratio of amplitude at the reference temperature point, k is the Boltzmann's constant, h is the Planck's constant, c is the velocity of light, .nu. is the Raman shift, .alpha. is the attenuation difference in the optical fiber between the Stokes light and the anti-Stokes light, and x is the distance, wherein the attenuation differenct .alpha. is represented by a function .alpha.{T(.tau.)} which is dependent on the temperature T(.tau.

Abstract: Improved thermooptical sensing devices are provided wherein at various predetermined sectons of an optical fiber is juxtaposed a material characterized by a temperature dependent index of refraction. This material forms a temperature sensitive area which controls the transmission of light through the optical fiber thereby allowing detection of temperature changes along the fiber. The materials may be crystalline thermoplastic polymers, modified organic polymers containing inorganic modifiers, polymer systems containing discrete phases of organic polymers and inorganic additives or thermochromic inorganic compounds.

Abstract: An apparatus and method for sensing temperature of a surface comprises a plurality of time domain intensity transmission networks. Each network comprises pairs of fiber optic power dividers which are connected to each other by bridges. One power divider in each pair is connected in a series by delay lines that form an output bus for propagating a light pulse supplied to an initial power divider in the output bus. This produces a train of light pulses which are returned to a light detector by a receiving bus which interconnects the power dividers at the opposite end of each bridge. Each power divider is in thermal contact with the surface whose temperature is to be measured and the intensity of the train of light pulses is changed in accordance with changes in the temperature of the surface.

Abstract: An optical fiber is installed to pass through a plurality of measurement places. Predetermined positions in the optical fiber are set at a predetermined temperature. When an optical signal is radiated on the optical fiber, Raman scattering occurs at various portions of the optical fiber. The intensities of the Raman scattered light components depend on temperatures. Backscattered light components of the Raman scattered light are sampled and stored in a memory. A temperature distribution on the optical fiber is obtained on the basis of the stored data. The temperatures of the mesurement places can be specified on the basis of the predetermined temperature on the obtained temperature distribution as a reference. The temperatures of the measurement places can be corrected on the basis of the predetermined temperature.

Abstract: A heater probe assembly used to heat treat a portion of a metallic tube that is surrounded by a heat sink is disclosed. The heater probe assembly heats the tube to a selected temperature range to relieve stress in and prevent degradation of the tube portion. The heater probe assembly includes an elongated probe body that is insertable and slidably movable within the tube portion. A radiant heat source is removably mounted on the probe body and heats the tube portion to incandescence within the selected temperature range. A temperature monitoring device monitors the temperature of the tube portion. The temperature monitoring device includes first and second optical measuring devices which determine the color of the tube portion at its longitudinally middle and end portions of the tube portion. An optical pyrometer translates the optical color measurement into a temperature measurement.

Abstract: An infrared thermometer (10) with a fixed aperture (99), focusable remote pickup head (12) conveys infrared light (16) from a target (14) to a photosensor (52) of a defocused sensor head (20). The remote pickup head (12) has a reimaging lens (84) and means for selectively adjusting the focus of the lens (84) relative to the target (14) after the pickup head has been fixedly mounted. The aperture setting is kept fixed during the focus adjustment to eliminate the need to recalibrate after the focus adjustment. The defocused sensor head (20) has a defocused relay lens (50) which is selectively out of focus to convey a slightly blurred, out of focus image of the output end of the fiber optic cable (18) to the photosensor (52) to reduce noise, average the light signal and reduce calibration difficulties due to high intensity spots in the image field and to make the unit less susceptible to misfocusing.

Abstract: In a method of measuring a quantity of heat, the distance between the position of an end of an exposed fiber portion before heating and the position of the end after heating is measured, and the quantity of heat applied to the end of the exposed fiber portion is calculated based on the distance. When heat is applied to an end of an exposed fiber portion, the end is fused and is rounded due to surface tension. For this reason, the position of the end of the exposed fiber portion retracts from the position it occupied before heating by the volume required for rounding the end. This retraction amount corresponds to a quantity of heat applied to the end of the exposed fiber portion. Therefore, by meauring the retraction amount, the quantity of heat applied to the ends of the exposed fiber portion can be quantitatively measured.

Abstract: Methods, materials and devices for the remote measurement of physical variables with fiber optic systems use a single excitation light source for generating through the use of at least one luminescence converter, both a signal beam and a reference beam, and allow the transmission of both beams through a single fiber to a single photodetector, thus producing photo-electric signals the relative intensities of which are only minimally affected by changes of the intensity of the interrogating light beam, optical losses, or detector drift. In contrast to the prior art, the luminescent materials of this invention can be used either as transducers for physical parameters or as means for processing information from other optical transducers, without requiring a change in the luminescence properties of said materials under the influence of the measured parameter.

Abstract: An apparatus for measuring temperature in a region of high temperature is disclosed herein. The measuring apparatus includes a sensor made from a fluorescent material, located within the region of high temperature. The fluorescent decay time of the fluorescent material is dependent upon the temperature of the fluorescent material. A first optical waveguide is located within the high temperature region and coupled to the sensor by means of a glass solder. The first optical waveguide is coupled to a second optical waveguide located outside the region of high temperature, and the second optical waveguide is connected to a means for detecting and evaluating the fluorescent radiation, also located outside the region of high temperature. A source of excitation radiation is used to cause the fluorescent material to fluoresce, and by measuring the fluorescence decay time, the temperature within the region can be determined.

Abstract: A radiation thermometer comprises a housing (1) within which is mounted a radiation detector system including a radiation sensor (2) positioned to receive radiation through a window (5) in the housing. The radiation detector system generates an electrical signal related to the sensed radiation. An optical signal generator (11, 14) is responsive to the electrical signal from the radiation detector system (9) and an internal housing temperature detector to generate a modulated optical signal whose frequency is related to the electrical signal from the radiation sensor and whose mark-space ratio is related to the signal from the internal temperature detector. The housing (1) is connectable with an optical waveguide, such as an optical fibre (16), into which the optical signal is coupled in use. A power source (13) is mounted within the housing (1) and is connected to the detector system (9).

Abstract: A single sensor is provided as part of a fiberoptic probe to measure up to three parameters, namely pressure (or force or displacement), temperature, and heat flow or fluid velocity. A solid elastomeric optical element is formed at the end of optical fiber transmission medium, and adjacent light reflective and temperature dependent materials are formed on the resulting convex surface of the optical element. The amount of light reflected is proportional to the force or pressure against the element. The temperature dependent material is preferably a luminescent material. Over the luminescent material is formed a layer of material that is absorptive of infrared radiation, thereby allowing a determination of characteristics of heat or fluid flow by measuring the rate at which heat is carried away from the infrared heated layer. The sensor can be formed at the end of a single optical fiber, thereby having extensive applications where a very small sensor is required.

Abstract: The pyrometer includes at least one optical fibre (10) transparent to infra-red made of fluorite glass, a reference emitter (20) of infra-red flux, an infra-red detector (30) for receiving the infra-red flux emerging from the optical fibre (10) or the infra-red flux originating from the reference emitter (20), a mechanical modulator (40) for infra-red flux positioned, in the direction of flux propagation, upstream of the infra-red detector (30) for periodically and successively interrupting the infra-red fluxes emerging from the optical fibre (10) and originating from the reference emitter (20), an electronic means of demodulation (50) for receiving the output signal from the detector (30) and a servo-control signal emitted by the mechanical modulator (40) in order to ensure a synchronized measurement, and a measuring apparatus (60) connected to the electronic demodulation means (50) for indicating the temperature to be measured of the target irradiating the optical fiber.

Abstract: A method of measuring the temperature in a high pressure furnace of a hot isostatic pressing apparatus, wherein a closed-end pipe having its inside communicated with the inside of the high pressure furnace and enabling a pressure medium to pass therethrough is disposed in the furnace, an incident top end of an optical fiber, a bundle of optical fibers or like other equivalent optical rod-like memeber is disposed to the open end of the closed-end pipe so as to be capable of receiving thermally radiated light from the inside of the closed-ended pipe and an exit rear end thereof is led out through a cover and to the outside of said high pressure vessel and a measuring system is connected to said exit rear end to detect heat radiation power from the top end of the closed-end pipe to thereby measure the temperature inside of the furnace.