Abstract: New diagnostics are presented that use a digital camera to measure full-field soot temperatures and soot volume fractions in axisymmetric flames. The camera is a Nikon D700 with 12 megapixels and 14 bit depth in each color plane, which was modified by removing the infrared and anti-aliasing filters. The diagnostics were calibrated with a blackbody furnace. The flame considered here was an 88 mm long ethylene/air co-flowing laminar jet diffusion flame on a round 11.1 mm burner. The resolution in the flame plane is estimated at between 0.1 and 0.7 mm. Soot temperatures were measured from soot radiative emissions, using ratio pyrometry at 450, 650, and 900 nm following deconvolution. These had a range of 1600–1850 K, a temporal resolution of 125 ms, and an estimated uncertainty of ±50 K. Soot volume fractions were measured two ways: from soot radiative emissions and from soot laser extinction at 632.8 nm, both following deconvolution. Soot volume fractions determined from emissions had a range of 0.1–10 ppm, temporal resolutions of 125 ms, and an estimated uncertainty of ±30%. Soot volume fractions determined from laser extinction had a range of 0.2–10 ppm, similar temporal resolutions, and an estimated uncertainty of ±10%. The present measurements agree with past measurements in this flame using traversing optics and probes; however, they avoid the long test times and other complications of such traditional methods.

Abstract: Thermal process of 1064 nm millisecond pulsed Nd:YAG laser irradiated silicon was time-resolved temperature measured by an infrared radiation pyrometer, temperature evolutions of the spot center for wide range of laser energy densities were presented. The waveforms of temperature evolution curves contained much information about phase change, melting, solidification and vaporization. An axisymmetric numerical model was established for millisecond laser heating silicon. The transient temperature fields were obtained by using the finite element method. The numerical results of temperature evolutions of the spot center are in good agreement with the experimental results. Furthermore, the axial temperature distributions of the numerical results give a better understanding of the waveforms in the experimental results. The melting threshold, vaporizing threshold, melting duration, and melting depth were better identified by analyzing two kinds of results.

Abstract: Siemens Energy, Inc. has been investigating the potential of a new approach to measuring the process gas temperature leaving the turbine of their heavy industrial gas turbine engines using an acoustic pyrometer system. This system measures the bulk temperature crossing a plane behinds the last row of turbine blades and is a non-intrusive measurement. It has the potential to replace the current intrusive multiple point measurement sensor arrays for both engine control and performance evaluation. The acoustic pyrometer is a device that measures the transit time of an acoustic pulse across the exhaust duct of the engine. An estimate of the temperature of the process fluid can be made from the transit time. Multiple passes may be made at various radial positions to improve the measurement. The gas turbine exhaust is a challenging environment for acoustic temperature measurement where there can be significant temperature stratification and high velocity. Previous applications of acoustic pyrometers to measure process gas temperature in power plants have been confined to applications such as boilers where rapid temperature changes are not expected and fluid velocity patterns are well known. The present study describes the results of acoustic pyrometer testing in an operating gas turbine engine under load using an active acoustic pyrometer system containing eight sets of transmitters and receivers, all external to the turbine exhaust flow path. This active method technology is based on the temperature dependence of the isentropic speed of sound from the simple ideal gas assumptions. Sound transmitters and receivers are mounted around the exhaust duct to measure the speed of sound. Very sophisticated topographical mapping techniques have been developed to extract temperature distribution from using any where from 2 to 8 sensors with up to 24 paths and 400 points. Cross correlation of sensor results to obtain topographical mapping of gas isotherms in a plane in full engine field tests have been conducted to prove the feasible of this technology on a gas turbine engine. The initial installation of the active acoustic pyrometer system in an engine exhaust was accomplished in 2009. All the tests indicate that the steady state measurements of the acoustic pyrometer system fall within 10C of the measured exhaust thermocouple data. An additional installation on a different model engine was subsequently made and data have been gathered and analyzed. Results of these tests are presented and future evaluation options discussed.Copyright © 2013 by Siemens Energy, Inc.

Abstract: The temperature of the flue-gas in the post combustion zone of a waste to energy (WTE) plant has to be maintained within a fairly narrow range of values, the minimum of which is prescribed by the European Waste Directive 2000/76/CE, whereas the maximum value must be such as to ensure the preservation of the materials and the energy efficiency of the plant. A high degree of accuracy in measuring and controlling the aforementioned temperature is therefore required. In almost the totality of WTE plants this measurement process is carried out by using practical industrial thermometers, such as bare thermocouples and infrared radiation (IR) pyrometers, even if affected by different physical contributions which can make the gas temperature measurements incorrect. The objective of this paper is to analyze errors and uncertainties that can arise when using a bare thermocouple or an IR pyrometer in a WTE plant and to provide a method for the in situ calibration of these industrial sensors through the use of suction pyrometers. The paper describes principle of operation, design, and uncertainty contributions of suction pyrometers, it also provides the best estimation of the flue-gas temperature in the post combustion zone of a WTE plant and the estimation of its expanded uncertainty.

Abstract: Experiments in high-energy-density physics often use optical pyrometry to determine temperatures of dynamically compressed materials. In combination with simultaneous shock-velocity and optical-reflectivity measurements using velocity interferometry, these experiments provide accurate equation-of-state data at extreme pressures (P > 1 Mbar) and temperatures (T > 0.5 eV). This paper reports on the absolute calibration of the streaked optical pyrometer (SOP) at the Omega Laser Facility. The wavelength-dependent system response was determined by measuring the optical emission from a National Institute of Standards and Technology-traceable tungsten-filament lamp through various narrowband (40-nm-wide) filters. The integrated signal over the SOP's ∼250-nm operating range is then related to that of a blackbody radiator using the calibrated response. We present a simple closed-form equation for the brightness temperature as a function of streak-camera signal derived from this calibration. Error estimates indicate that brightness temperature can be inferred to a precision of <5%.

Abstract: Numerical simulations of in-cylinder soot evolution in the optically accessible heavy-duty diesel engine of Sandia National Laboratories have been performed with the multidimensional conditional moment closure (CMC) model using a reduced n-heptane chemical mechanism coupled with a two-equation soot model. Simulation results are compared to the high-fidelity experimental data by means of pressure traces, apparent heat release rate (AHRR) and time-resolved in-cylinder soot mass derived from optical soot luminosity and multiple wavelength pyrometry in conjunction with high speed soot cloud imaging. In addition, spatial distributions of soot relevant quantities are given for several operating conditions.

Abstract: This paper addresses the behavior of a high-current vacuum arc after current zero (CZ). Langmuir probes operating in the electron saturation current mode are used to detect the time of arrival of the cathode sheath at the probe position. The probe current is measured just before and after the CZ followed by transient recovery voltage both with and without external axial magnetic field (AMF). For an AMF-stabilized arc, the plasma sheath expanded radially with respect to the electrode axis, whereas for an arc with no AMF, the sheath boundary expanded rather spherically away from the anode. The anode temperature immediately after the CZ is estimated using the optical pyrometry method. Thermal radiation of a hot sample is recorded using a HSFC four-channel high-speed camera. Each camera channel is equipped with an interference filter to record radiation at a particular wavelength (600, 700, 775, and 825 nm). The camera channels are preliminarily calibrated. The calibration sample is a molybdenum crucible with a known spectral emissivity.

Abstract: Different monitoring methods for the laser additive manufacturing process were studied in this study. Possibilities and downfalls of three different methods were compared to each other to define their applicability in future on-line and adaptive monitoring use in LAM processes. The material used on all the LAM process tests was EOS StainlessSteel PH1 in fine powder form. In this study, e.g. parameters like scanning speed, layer thickness and hatch space were tested. Based on the results of this study, the pyrometer seems to be more easily adaptable to continuous monitoring than the spectrometer or systems based on active illumination imaging system. It seems that the pyrometer is a promising method for quality control. The ability to control quality through on-line measurements can be further utilized in future e.g. for on-line quality control and dynamic process control, i.e. the ability to change and correct parameters on the fly.

Abstract: In this paper, a method based on the ordinary least squares method for optimising the wavelength selection used for the multi-spectral temperature measurement of surfaces exhibiting non-uniform temperature-depending emissivity is presented. The goal consists of minimising the standard deviation of the estimated temperature (optimal design experiment). Two methods for wavelengths selection are presented – sequential and global with or without constraints – on the spectral range. Then, the estimated temperature results obtained by two different models taking into account a second-order polynomial transfer function including the emissivity and for different number of parameters and wavelengths are compared. The first model is based on Wien’s approximation and fluxes ratio (as done in the bicolour temperature technique) and the other is based on the fluxes (Planck’s law but without fluxes ratio). Different selection criteria are presented. These points are treated from theoretical, numerical and experimental ...

Abstract: Temperature measurements within the highly complex reaction field of energetic materials are complicated but existing technology enables point source measurements that identify a maximum temperature at a single location. This study presents a method to extend point source measurements to thermally map the spatial distribution of temperature over a large field of interest. The method couples point source temperature measurements from a multi-wavelength pyrometer with irradiance measurements from an infrared camera to produce a highly discretized thermal map that includes the reaction and surrounding field. This technique enables analysis of temperature gradients within the field of interest and an understanding of energy propagation beyond the point of reaction. Point source measurements of maximum temperature are within 10% of reported values. The method was illustrated for the aluminum and polytetrafluoroethylene reaction and the thermal distribution of temperature produced 30 720 temperature measurements over a field of interest corresponding to 3.5 cm × 8 cm.

Abstract: This paper proposes a method for measuring the tool edge temperature during tapping. The infrared ray from the tool edge of the tapping tool was measured using a two-color pyrometer with an optical fiber. In addition, the vibration caused by contact between the first-act tool edge and the workpiece was sensed by an acceleration pickup. The outputs of the pyrometer from the tool edges and chips could be distinguished by analyzing the cutting behavior in the tapping process. The tool edge temperature was successfully measured for tapping of AISI 1045-based free-machining steel and stainless steels. The cross-sectional cutting area appears to control the tool edge temperature. The maximum tool edge temperatures with thee two steels at a cutting speed of 30 m/min reached almost 300 and 400 oC, respectively. The cutting torque for stainless steel 303 was 3.4 N•m lower than when tapping stainless steel 304. The tool edge temperature for stainless steel 304 reached the maximum value of 510 ̊C. The temperature for stainless steel 303 was about 100 ̊C lower than of stainless steel 304.The tool edge temperature for stainless steel 304increased linearly with the cutting speed. The rate of increase in the tool edge temperature with increase in cutting speed from 25 m/min to 30 min was larger than that from 20m/min to 25min. Therefore, the tool edge surroundings apparently became harder with an increase of cutting speed.

Abstract: Optical and thermophysical properties of pure metals at the melting point and in the liquid phase are of general interest for technological applications. This is especially true for those metals that are commonly applied. Many of these elements are used either in their pure form or as alloying components. Due to their widespread use in industry an ongoing need for new and more accurate data exists. Based on an ohmic pulse-heating apparatus, properties of conducting materials can be obtained from temperatures of about 1200 K, at which most metals are in the solid state, up to about 5000 K in the liquid state. To enable a fast and accurate temperature measurement over such a vast range, pyrometric temperature detection based on Planck's radiation law is employed. Furthermore, a microsecond-resolution ellipsometric device with no moving parts, called μs-DOAP (Division-of-Amplitude-Photopolarimeter) as first described by Azzam [1], is applied to measure normal spectral emissivity close to the wavelength of the pyrometer (650 nm). In the present paper, measurements of normal spectral emissivity at 684.5 nm, obtained by means of the above-mentioned pulse-heating technique combined with a μs-DOAP, are summarized for 18 metals, namely cobalt (Co), copper (Cu), gold (Au), hafnium (Hf-3%Zr), iron (Fe), iridium (Ir), molybdenum (Mo), nickel (Ni), niobium (Nb), palladium (Pd), platinum (Pt), rhenium (Re), silver (Ag), tantalum (Ta), titanium (Ti), tungsten (W), vanadium (V) and zirconium (Zr). The results are very important in order to eliminate uncertainties arising from the unknown behavior of emissivity at melting and in the liquid phase when investigating temperature-dependent thermophysical properties.

Abstract: A method of in-situ temperature measurement for a wafer treatment reactor such as a chemical vapor deposition reactor desirably includes the steps of heating the reactor until the reactor reaches a wafer treatment temperature and rotating a wafer support element within the reactor about a rotational axis. The method desirably further includes, while the wafer support element is rotating about the rotational axis, obtaining first operating temperature measurements using a first operating pyrometer that receives radiation from a first portion of the wafer support element, and obtaining first wafer temperature measurements using a wafer temperature measurement device that receives radiation from at least one wafer, the wafer temperature measurement device located at a first position.

Abstract: Expert-system spectropyrometers have been available for fifteen years. The large volume of data collected has confirmed that emissivity is best described as a property of a sample's condition rather than a property of a material; any conventional pyrometer that depends on assumed behavior or tabulated values of emissivity is unlikely to be accurate. The advanced spectropyrometric technique in radiation thermometry discussed herein uses hundreds of narrow wavebands over broad spectral bandwidths to accurately measure temperatures despite initially unknown and constantly changing emissivity. Metals and especially liquid metals are an extreme example; these exhibit substantial changes in both the magnitude and the spectral dependence of emissivity with time and processing. The spectropyrometer determines emissivity behavior from the data collected for every measurement, displaying and saving the thermal spectra as well as temperature, the tolerance, and emissivity. Extensive testing carried out by many third...

Abstract: We have investigated process monitoring of laser beam welding with a TruDisk disk laser to detect process faults. Additionally to monitoring laser beam welding processes by a conventional VIS camera an NIR (near-infrared) camera reveals new information. Our sensor detects thermal radiation between 1100 and 1700 nm from the weld zone, which represents surface temperatures above 1000 K. Using the thermal radiation from the process we can observe all major weld defects without auxiliary illumination. The camera is integrated in a standard TRUMPF welding optics for on-axis observation. A real-time image processing system analyzes the camera images regarding welding irregularities and delivers information to characterize the weld process and its result. Actually, we perform an online passive heat-flow thermography that uses the process itself as the heat source and that probes the thermal attributes of the seam. By this means we can detect regions of bad fusion (“false friends”) virtually during the welding process. In addition to conventional thermography we have investigated the use of ratio pyrometry by using to NIR-cameras that observe the process in two different spectral bands. By considering the pixel-per-pixel ratio the influence of surface effects it greatly reduces and we obtain images of the weld zone with an absolute temperature scale. We have compared ratio pyrometry measurements with conventional thermography.

Abstract: A radiation thermometer (pyrometer) has been built that is relatively low cost but is shown will be capable of providing calibration and industrial laboratories with National Measurement Institute primary standard levels of uncertainty traceable to the kelvin at temperatures above 1300 K following proposed changes to the mise en pratique for the definition of the kelvin.

Abstract: Hypersonic (re-)entry flight vehicle designs are dominated by the thermal protection systems (TPS) required to keep the payload safe. The knowledge of the thermal loading experienced throughout a flight trajectory is critical for the optimal design of the TPS. The thermal loading information is predominantly acquired from extensive ground testing and computational modelling. The ability to obtain high fidelity ground test data is critical for the development and refinement of the computational models used, which then allows for a more accurate and efficient design of TPS for hypersonic vehicles. This thesis presents a new hot wall model method for testing carbon-carbon models at realistic wall temperatures (2000 – 3000 K) in hypersonic impulse facilities. This greatly extends the model wall temperature range possible in impulse facilities from the previous maximum of ~ 1200 K. This opens up a whole new range of hypersonic testing, in particular for (re-)entry vehicles which are characterised by very high wall temperatures and are commonly constructed using carbon fibre based materials. This new methodology has been tested in the X2 expansion tube at the Centre for Hypersonics within The University of Queensland. Models have been tested in an 8.8 km/s Earth re-entry flight equivalent flow field. A set of hemicylindrical models with a diameter to length ratio of 4.5 were constructed and tested. Three different models types were used; an aluminium reference model, cold carbon-carbon models and heated carbon-carbon models. To measure the wall temperature during testing, two high temperature measurement techniques were developed; firstly using a two colour ratio pyrometry technique with a commercially available digital single lens reflex (DSLR) camera, and secondly using a visible near infrared spectrometer. These techniques are capable of measuring temperatures beyond the range available to standard thermocouples (limited to ~1400 K). The metric used to evaluate the effect of the wall temperature on the flow field was the formation of cyanogen due to a surface chemistry reaction between the nitrogen in the air flow and the carbon model. Measurements were taken using a Ultraviolet (UV) spectrometer that was coupled to an intensified charge-coupled device (ICCD) camera for spatially resolved data, and to a photo multiplier tube (PMT) for temporally resolved data. These measurements were taken for all three model types. The results of the UV spectroscopy clearly indicate that the radiation of cyanogen is greatly increased due to the rise in model wall temperature. This is particularly apparent in the boundary layer where measured intensity of the cyanogen molecules is the greatest. This clearly indicates that there thermal surface effects present in this impulse facility testing which have not previously been possible in these facilities. This technique can now be used to investigate other phenomena affected by the thermal surface effects such as, for example, boundary layer development, catalycity and surface thermochemistry. The next step for this work is to conduct (subscale) re-entry vehicle tests with realistic wall temperatures and compare this data to flight data and computational models.

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: A comparison between two different types of thermal radiation sources maintaining near blackbody conditions has been carried out in the range from 50 to 500 °C. An infrared total radiation pyrometer was used as a transfer standard to measure the temperature of blackbodies. A thorough study of temperature distribution has been carried out for the large surface source in order to characterize the best location over the surface blackbody for temperature determination precisely of the order of better than 0.1 °C. The expanded uncertainty in the estimation of temperature of the radiating source in the above range of measurement was evaluated to be within ±0.24 °C at 50 °C and ±0.88 °C at 500 °C. The blackbody temperature sources found to be suitable for calibration of infrared total radiation pyrometers and thermal imaging devices in the operational range as mentioned above for laboratory use or other industrial and medical applications.

Abstract: Accurate temperature measurement remains a challenge for microwave heating of powder materials. We propose a temperature calibration method based on exothermic reactions and the resultant thermal runaway that occurs during microwave heating. The approach was demonstrated on microwave heating of four titanium alloys. Differential scanning calorimetry was used to determine the threshold reaction temperature for each selected titanium alloy. This served as a standard for the microwave heating of these titanium alloys. Infrared pyrometric temperature measurements were then calibrated by comparing the starting temperature of each thermal runaway event with the threshold reaction temperature.

Abstract: A flat light emitting plate, a method for calibrating a pyrometer and a method for determining the temperature of a semiconducting wafer inside a processing chamber by said pyrometer. The invention provides a method for calibrating a pyrometer by means of a cold source which is also applicable to processing chambers with a narrow slit. According to the invention, a flat light emitting plate for simulating thermal radiation is provided, comprising a main body made of a transparent material, a light emission area located on an upper surface of the light emitting plate for emitting light, at least one light source located on a lateral surface of the light emitting plate, at least one detector located on a lateral surface of the light emitting plate, and a regulating circuit for adjusting the intensity of light emitted by the light sources.