A new facility for the measurement of spectral emittance (emissivity) of materials that employs a set of blackbody sources is being built at NIST. This facility has also been used to investigate the capabilities of Fourier transform (FT) spectrometers to characterize the spectral emissivity of blackbody sources. The facility covers the spectral range of 1 μm to 20 μm and temperatures from 600 K to 1400 K. The principle of operation involves the spectral comparison of an unknown source with a group of variable temperature and fixed point reference sources by means of the FT spectrometer and filter radiometers. Sample surface temperature is measured by non-contact method using a sphere reflectometer. The current reflectometer setup allows measurements of opaque samples, but it is planned to include semitransparent materials at a later stage.

Ceramics are used as construction materials for buildings and thermal technical plants. Depending on the fields of its application between ambient temperature and more than 1000 °C there are different ceramic materials in use. For the temperature measurements with pyrometers and infrared cameras band emissivities are needed as settings. Pyrometers and infrared cameras have different spectral work ranges. Therefore, for different devices different emissivities are needed for one and the same material. Selectivity of the spectral emissivities like with ceramic materials can lead thereby to larger differences between the emissivities of a material, and furthermore to temperature dependence of the band emissivities of a material. Examples of different temperature-dependent spectral, band, and total emissivities are shown. These emissivities for different work ranges of pyrometers and infrared cameras were computed based on measured spectral emissivities. The investigation leads to a selection of suitable band emissivities for radiation thermometry of ceramics.

Fundamental to the design of an infrared sensor is controlling the stray light and internal radiation emission. A series of Bi-directional Reflectance Distribution Function (BRDF) measurements at two infrared bandpasses in the MWIR and LWIR were acquired. Incident beams were oriented 10 and 60-degrees from normal. Forward-scatter (key to baffles and cold-shields) data is presented for infrared black surface preparations including: anodizing, copper oxide, nickel oxide, black paints, and trademarked black surfaces. Comparison is also made between selected surfaces before and after exposure to 78 Kelvin (LN2) thermal cycles. This paper also includes scanning electron microscope (SEM) images and discrete Fourier transform (DFT)) measurements for selected black surfaces, including comparisons of damaged and undamaged nickel oxide.

A multi-wavelength expert-system pyrometer based on a grating spectrophotometer has been able to overcome many well-known difficulties of pyrometry. These include unknown, changing, and/or spectral dependence of emissivity as well as environmental absorption of radiation. In addition to a spectrophotometer and the usual optics, the instrument includes a computer which analyzes each measurement and then returns the temperature, the tolerance (a real-time measure of accuracy), and the signal strength (a quantity directly related to the emissivity at a chosen wavelength). The instrument can save the input data, the thermal spectrum, for each temperature measurement. Accuracy to 0.10% is routinely achieved.

Infrared radiation thermometry has in the past decade seen remarkable success in measuring human body temperature, as evidenced by the many variations on the Infrared Ear Thermometer. There are other devices and additional motivation to speed detection and reduce uncertainty in measurement of elevated temperature in humans, particularly on a mass basis. All the devices employing the various techniques must meet very high standards for equipment performance and calibration stability to be successful. This paper presents an overview of the present status of the various measurements and standards.

The use of infrared tympanic thermometers for monitoring patient health is widespread. However, studies into the performance of these thermometers have questioned their accuracy and repeatability. To give users confidence in these devices, and to provide credibility in the measurements, it is necessary for them to be tested using an accredited, standard blackbody source, with a calibration traceable to the International Temperature Scale of 1990 (ITS-90). To address this need the National Physical Laboratory (NPL), UK, has recently set up a primary ear thermometer calibration (PET-C) source for the evaluation and calibration of tympanic (ear) thermometers over the range from 15 °C to 45 °C. The overall uncertainty of the PET-C source is estimated to be ± 0.04 °C at k = 2. The PET-C source meets the requirements of the European Standard EN 12470-5: 2003 Clinical thermometers. It consists of a high emissivity blackbody cavity immersed in a bath of stirred liquid. The temperature of the blackbody is determined using an ITS-90 calibrated platinum resistance thermometer inserted close to the rear of the cavity. The temperature stability and uniformity of the PET-C source was evaluated and its performance validated. This paper provides a description of the PET-C along with the results of the validation measurements. To further confirm the performance of the PET-C source it was compared to the standard ear thermometer calibration sources of the National Metrology Institute of Japan (NMIJ), Japan and the Physikalisch-Technische Bundesanstalt (PTB), Germany. The results of this comparison will also be briefly discussed. The PET-C source extends the capability for testing ear thermometers offered by the NPL body temperature fixed-point source, described previously. An update on the progress with the commercialisation of the fixed-point source will be given.

Temporal artery (TA) thermometry was developed in answer to requests by pediatricians for a replacement for: 1) ear thermometry due to inaccuracy; and 2) rectal thermometry due to parents’ (and most clinicians’) growing dislike of the method. The underlying technology development spans some 20 years, borrowing heavily from methods invented for industrial processes and medical research. Although the forehead has been used since antiquity to detect fever, its accuracy had always been questionable until physiological artifacts were understood and overcome, and mathematical modeling of arterial heat balance at the skin has made it possible to produce accurate core temperatures entirely non-invasively with just a scan of the forehead. Clinical studies have been conclusive as to TA superiority to ear thermometry, and well on the way to being conclusive as to TA at least as accurate as rectal. The physics are relatively straightforward, but the physiological requirements are not. Underlying physiological artifacts cause errors of more than 2 deg C in non-invasive thermometry and must be reduced by an order of magnitude to provide medically useful temperatures. Patented TA technology incorporates methods of dealing with physiological artifacts to overcome these errors. Mass screening for SARS containment with this method is examined.

The Infrared Fever Screening System (IFSS), conceptualised by Singapore's Defence Science and Technology Agency (DSTA) and Singapore Technologies Electronics during the 2003 SARS outbreak, is the first infrared-based system in the world to be used for fever screening of large groups of people. The IFSS does not measure skin temperature but uses a two-point detection concept to screen for fever. The first decision point is to sieve out probable febrile persons using thermal imagers and the second decision point is the confirmation that the subject has an elevated body temperature using conventional clinical thermometers. Statistics, physics and human physiology were key inputs in the design of the IFSS. Workflow and other operational considerations such as operator training are also important in ensuring the performance of the IFSS. This paper shares our experience in the development and deployment of the IFSS.

Mainly four types of thermal imaging systems for mass fever screening have been identified. The system set-up, working principle, advantages and limitations of each type are described and analysed. A set of critical parameters, which affects the performances of the thermal imaging system for mass fever screening, has been established. The effectiveness of each type of thermal imaging system is evaluated against the set of critical parameters using developed measurement protocol. The evaluation results are summarised.

This paper evaluates the effectiveness of thermal scanner when it is being used for mass blind screening of potential fever subjects. Both regression and ROC curve are used to analyze the data collected from the SARS hospital in Singapore and conclusive results are drawn from them. These results will be vital in determining two very important information: the best and yet practical region on the face to take readings and optimal pre-set threshold temperature for the thermal imager.

SARS (Severe Acute Respiratory Syndrome, commonly known as Atypical Pneumonia in mainland China) caused 8422 people affected and resulting in 918 deaths worldwide in half year. This disease can be transmitted by respiratory droplets or by contact with a patient's respiratory secretions. This means it can be spread out very rapidly through the public transportations by the travelers with the syndrome. The challenge was to stop the SARS carriers traveling around by trains, airplanes, coaches and etc. It is impractical with traditional oral thermometers or spot infrared thermometers to screen the tens of travelers with elevated body temperature from thousands of normal travelers in hours. The thermal imager with temperature measurement function is a logical choice for this special application although there are some limitations and drawbacks. This paper discusses the real SARS applications of industrial infrared cameras in China from April to July 2003.

Blood glucose monitoring is essential for management of diabetes especially for those patients who requires regular insulin injections. A reliable noninvasive technique may eliminate inconvenience associated with frequent skin puncture to draw blood for measurement by a standard meter. Laser-induced thermal waves in tissue and detection of resulting IR response may provide a valuable approach to development of noninvasive glucose sensor. The present report analyzes radiometric response of tissue at the two wavelengths in mid-IR spectral band with phase-sensitive detection to evaluate feasibility of differential phase radiometry for noninvasive glucose monitoring. Sensitivity of the differential phase method is computed using two models of laser-tissue interaction: homogeneous light absorption and a discrete chromophore heating.

We conducted a preliminary IR imaging study of blood circulation in patients with peripheral vascular diseases. Abnormal blood flow is common in older adults, especially those with elevated blood lipids, diabetes, hypertension, and a history of smoking. All of these conditions have a high prevalence in our population, often with more than one condition in the same individual. The differences in blood flow is revealed by temperature differences in areas of the extremities as well as other regions of the body. However, what is needed is an imaging technique that is relatively inexpensive and can reveal the blood flow in real time. The IR imaging can show detailed venous system and small tempearture changes associated with blood flow. Six patients with vascular diseases were tested in a clinic set up. Their legs and feet were imaged. We observed large temperature differences (cooling of more than 10° C) at the foot, especially toes. More valuable information were obtained from the temperature distribution maps. IR thermography is potentially a very valuable tool for medical application, especially for vascular diseases.

Most aerial infrared (IR) is performed by the military, but there are commercial uses. Some of these non-military applications are the focus of this paper. Generally speaking, the farther away one can get from the object of an infrared survey, while maintaining the needed spatial resolution and thermal sensitivity, the more usable the data is. Wide areas and large objects can be effectively imaged from the air. In fact, the use of high-resolution aerial infrared imagery is often the only way that one can see slight nuances of temperature differences and trace the patterns of heat. In order to produce an easy to understand, high quality and useable report, the data must be acquired, recorded and processed in an efficient and effective way. This paper discusses the ongoing advances in methodology, platform and equipment required to produce high quality usable data for the end-user.

The standard air tightness test of containers is based on measurement of global parameters as the outlet of a specific gas, detected by specialised mass spectrometers. The identification and location of air leakages is extremely important especially for the container manufacturer. At the same time, the measure of the mass flux is of importance. IR Thermography has been successfully applied for leakages detection on buildings, but unfortunately, the noise due to The standard air tightness test of containers is based on measurement of global parameters as the outlet of a specific gas, detected by specialised mass spectrometers. The identification and location of air leakages is extremely important especially for the container manufacturer. At the same time, the measure of the mass flux is of importance. IR Thermography has been successfully applied for leakage detection on buildings, but unfortunately, the noise due to environment limits its applicability, particularly in case of a small flux. A new thermal procedure has been developed for the leakage detection. The technique is based on the stimulation of the envelope with a low oscillating heat flux and lock-in analysis. An airflow is injected, with a harmonically varying flowrate and a slightly higher temperature than the ambient. Then, the thermograms sequence is analyzed in the frequency domain. A review of quantitative techniques for the convective heat exchange measurement is reported. The procedure has been utilized for special containers used for both transport and exhibition of pictures inside museums. Tests performed before and after gaskets improvements show the capability of the technique to estimate qualitatively the airflow.

Water Intrusion with resulting damage is too common in many of today's newly constructed buildings. On the positive side of this problem, the original drawings and contractors are generally available to resolve the issues. At the very least, comparable materials are available so that the building can be repaired. With older buildings however this process is not so easy. Depending on how old the building actually is, the original builders usually are retired or deceased and the drawings of the building no longer exist. Needless-to-say, when a vintage building has water intrusion problems, investigation of the causes can be very challenging requiring different test methods to find a solution. This is the case with the study presented in this paper. The project undertaken was a circa 1920s building. Over 70-some years, this building had gone through multiple facade modifications and structural additions. So, not surprising, there was a history of water intrusion problems with deterioration of the interior walls and connected flooring. During the Florida rainy season, the most recent severe water intrusion leant to further damage of the same areas. This damage prompted an overall assessment of the building for the extent of structural deterioration. This was requested by its owner for safety compliance. This paper presents the results of the infrared study performed as well as a borescopic/visual examination on the 1920s brick over terra cotta block structure.

Although, the efficiency of IRT (infrared thermography) as a NDT & E technique in the literature it is well documented, in the investigation of historic structures, where a restoration or conservation treatment can cause irreversible damage to the structure, it is considered to be of most importance. IRT is a non-destructive investigation technique that can be widely used due to the outstanding advantages that offers in a number of applications and specifically in the assessment of structural materials and techniques. In the present work, both IRT approaches, passive and active, were used, depending on the application, for the investigation of traditional-historical materials and structures. IRT was applied on restoration and traditional-historic materials and structures for the evaluation of conservation interventions (materials and techniques) concerning cleaning of architectural surfaces, restoration of masonries by repair mortars, as well as the disclosure of tesserae on plastered mosaic surfaces. For this reason, diagnostic studies on historical sites and structures took place. Wherever necessary, the emissivity values of the investigated materials were taken into account, after their determination in the laboratory on representative samples. Furthermore, in order to obtain useful information from the IRT surveys various properties (thermal, optical, physical) of the examined materials were taken into account. The outcome of this work provides strong evidence that IRT is an effective technique for the evaluation of historic buildings and sites.

The use of the infrared thermography techniques is progressively showing as an important tool in the research of very different thermal applications, in this case air conditioning systems. The Instituto de Ingeniería Energética de la Universidad Politécnica de Valencia has developed a Joule Project, financed by the European Community for the Study and Characterization of propane heat pumps, adapted to the use in the South European countries. The substitution of the fluorocarboned refrigerants by natural fluids as propane is the main objective of this project. With the study, important efficiency improvements have been obtained, in relation with the use of the classical refrigerants, for both summer and winter conditions. The use of the thermography in this project has been quite useful in the achievement of several important tasks as the study of the compressor start up process, as it is described in the paper.

Recently infrared signature simulation has been in a state of great interest. Although various models have been developed to generate synthetic image of infrared scenes, little work has been done to create high fidelity infrared image of bridge. In this paper a realistic model for infrared image synthesis of bridge based on its thermal energy transmission is proposed to generate the infrared image of bridge at different time. Our new IR image synthesis model of bridge accounts for meteorological, environmental, material and artificial factors. Then an energy equilibrium equation is built based on the principle of heat transfer and infrared physics. And a finite difference method is adopted to solve the equations. Finally we get the radiance distribution of target surface. To get high fidelity, the effect of atmosphere is added using LOWTRAN model. The value of attenuation is pre-computed and stored in our database. We also pre-generate infrared texture and depth attenuated image from visible image. Infrared images of bridge from different viewpoints at different time can be rendered. Our results of simulation show that the model is robust and feasible.

A new model for realistic IR image rendering of city buildings was proposed in this paper. Within the model, We first analyzed the main kinds of factors affecting the infrared characteristic of city buildings such as air temperature, relative humidity, wind speed, sun and sky radiations. Then we established an energy equation based on principle of energy equilibrium for the surface parts of city building scene and by adopting multi-layer infinite difference method and Gauss-Seidier’s iterative method, the surface temperatures of building scene under various conditions were acquired. To make the IR scene more realistic, we proposed a new method to obtain IR texture from its corresponding visible image based on the spectral correlation and the thermal attribute of the classified materials in scene. Using Ray tracing to determine IR shadow area and render the IR scene of city building with high-reality. To simulate the attenuated and blurred effect of atmosphere, we propose an IR attenuation imaging model. Finally, various IR images of city buildings at different time in a day and at different detected distance are realistically rendered based on our model.

A cubic-phase distribution is applied in the design and fabrication of inexpensive lenses for passive infrared motion sensors. The resulting lenses produce a point spread function (PSF) capable to distinguish the presence of humans from pets by the employment of the so-called wavefront coding method. The cubic phase distribution used in the design can also reduce the optical aberrations present on the system. This aberration control allows a low tolerance in the fabrication of the lenses and in the alignment errors of the sensor. The lens was manufactured on amorphous hydrogenated carbon thin film, by employing well-known micro fabrication process steps. The optical results demonstrates that the optical power falling onto the detector surface is attenuated for targets that present a mass that is horizontally distributed in space (e.g. pets) while the optical power is enhanced for targets that present a mass vertically distributed in space (e.g. humans).

Thermal imaging has recently been introduced in volcanology to analyse a number of different volcanic processes. This system allows us to detect magma movements within the summit conduits of active volcanoes, and then to reveal volcanic activity within the craters even through the thick curtain of gases usually released by volcanoes such as Mt Etna and Stromboli. Thermal mapping is essential during effusive eruptions, since it distinguishes lava flows of different age and concealed lava tubes’ path, improving hazard evaluation. Recently, thermal imaging has also been applied to reveal failure planes and instability on the flanks of active volcanoes. Excellent results have been obtained in terms of volcanic prediction during the two recent eruptions of Mt Etna and Stromboli, both occurred in 2002-2003. On Etna, thermal images monthly recorded on the summit of the volcano revealed the opening of fissure systems several months in advance. After the onset of the flank eruption, daily thermal mapping allowed us to monitor a complex lava flow field spreading within a forest, below a thick plume of ash and gas. At Stromboli, helicopter-borne thermal surveys allowed us to recognise the opening of fractures along the Sciara del Fuoco, one hour before the large failure that caused severe destruction on the island on 30 December 2002. This was the first time ever that volcanic flank collapse has been monitored with a thermal camera. In addition, we could follow the exceptional explosive event of the 5th April 2003 at Stromboli from helicopter with a thermal camera recording images immediately before, during and after the huge explosion. We believe that a more extended use of thermal cameras in volcano monitoring, both on the ground and from fixed positions, will significantly improve our understanding of volcanic phenomena and hazard evaluations during volcanic crisis.

The reliability of GIS is very high but any failure that occurs can cause extensive damage result and the repair times are considerably long. The consequential losses to system security and economically can be high, especially if the nominal GIS voltage is 420 kV and above. In view of these circumstances, increasing attention is being given to diagnostic techniques for in-service maintenance undertaken to improve the reliability and availability of GIS. Recently considerable progress has been made in diagnostic techniques and they are now used successfully during the service life of the equipment. These diagnostic techniques in general focus on the GIS insulation system and are based on partial discharge (PD) measurements in GIS. There are three main methods for in-service PD detection in GIS: - the chemical method that rely on the detection of cracked gas caused by PD, the acoustic method designed to detect the acoustic emission excited by PD, and, the electrical method which is based on detection of electrical resonance at ultra high frequencies (UHF) up to 1.5 GHz caused by PD excitation in GIS chambers (UHF method). These three dielectric diagnostic methods cannot be used for the detection of poor current carrying contacts in GIS. This problem does not always produce partial discharges and at early stages it does not cause gas cracking. An interesting solution to use two techniques - the current unbalance alarm scheme and partial discharge monitoring was advised by A. Salinas from South California Edison Co. Unfortunately this way is complicated and very expensive. The investigations performed in Japan on standing alone SF6 breaker showed that joule heating of the contact accompanied by released power of 1600 Watt produce temperature difference on the enclosure up to 7 degrees centigrade that could be detected by infra-red Thermal Imaging System. According to CIGRE Joint Working Group 33/23.12 Report, 11% of all GIS failures are due to poor current carrying contacts in GIS. The Israel Electric Company (IEC) in seeking a solution to this problem have undertaken experimental work to examine the possibility of in-service diagnostic of poor contact problem in GIS via direct local heating detection, using a Thermal Imaging System. The experiments were carried out on the part of the GIS with nominal SF6 pressure. The following aspects of the problem were examined: - the range of power released in the defective contact that could give the practical temperature rise on the surface of enclosure; - temperature distribution on the surface of enclosure; - the influence of spacer type (with holes or without) on the heat transfer process; - the influence of the length of SF6 tubes and there position (horizontal or vertical); - the temperature difference between upper and lower parts of the tubes in horizontal position; - practical use of the Thermal Imaging System for detecting poor contact problem in GIS.

In refineries, thermal imaging has been used for many years to monitor the interior temperatures of furnaces, particularly the furnace wall-tubes, in the presence of combustion gas flames. The temperature range in these processes varies from 400 to 1200°C. Flame combustion byproducts contain gases of H₂O, N₂, CO₂, NO and small residues of ashes and other particles that emit thermal radiation toward wall tubes resulting in heating of the tubes. Typically, a mid-infrared (MWIR) instrument is used, equipped with a narrow band-pass filter centered at 3.90μm. In this band there is a void in the emission spectrum of these gases making them transparent, and an instrument operating only in this band can provide very high quality thermal images of the furnace interior. Operating temperatures at other points in petrochemical-related processes, closer to ambient temperature, can also be very critical. For example, a 10°C temperature difference from desired temperature at the coil output of a heat exchanger of a large ethylene plant can result in substantial revenue loss per year. Monitoring of these conditions is usually accomplished using a long wave infrared (LWIR) imaging radiometer operating in the 8-14μm spectral bands. This paper will review the evolution of techniques for furnace wall-tube monitoring, discuss current techniques and conclude with the description of a modern dual-band approach. In this approach a single, portable uncooled thermal imager is deployed in a refinery to monitor both the status of high temperature elements such as wall tubes and the operating condition of the furnace and its ancillary equipment. Case histories with thermographic illustrations will be presented.

The main special feature of elaborated method is that the dynamic IR thermography (DIRT) bases on forming of single image consisting of pixels of chosen minimum (IMAX) or maximum (IMAX) value, noted during adequately long sequence of thermograms with total independence to the moment of its (image's) capture. In this way, additive or suppressed interferences of fluctuating character become bypassed. Due to this method thereafter elaborated in classic way such “artificial thermogram” offers the quality impossible to achieve with a classic “one shot” method. Although preliminary, results obtained clearly show great potential of the method. and confirmed the validity in decreasing errors caused by fluctuating disturbances. In the case of process furnaces of gas-fired type and especially of coal-fired, application of presented solutions should result in significant increasing the reliability of IR thermography application. By use of properly chosen optical filters and algorithm, elaborated method offers a new potential attractive to test temperature problems other than in tubes , as for example symmetry and efficiency of the furnace heaters.

In chemical tankers one crucial concern is the control of thermal insulation of the tanks. Chemical tanker construction techniques may vary, but usually the tanks, as stand alone sandwich structures, are put inside the bulk almost at the final stage of the ship construction. In the case of the present survey, the tanks were composed of three main layers: a framed inner metal surface; a polyurethane (PU) foam layer; an outer thin metal plate surface. The PU is applied by injection between the metal layers. The main parameter to control during this operation is the PU density: a not homogeneous distribution of PU can lead to a bad insulation. To check the quality of the insulation, the inner space of the tank could be heated and the temperature distribution of the outer surface monitored through an IR camera (check of thermal leaks). This methodology is well suited if the survey is carried out on the tank before the installation on board. For tanks already installed, as in our case, it is difficult to analyse the tanks by managing the camera in the narrow hollow spaces between tank and bulk. So a refrigeration plant has been used in order to lower the temperature inside each of the tanks below 0 °C. The IR analysis has then been conducted on the tanks inner surfaces in order to highlight possible hot spots due to thermal fluxes from the outer to the inner surfaces.

Thermography is a powerful tool for locating or verifying levels in tanks and silos. But one could ask “Why bother?” All too often existing level indication instruments are simply not reliable or positive verification of instrumentation readings is required. When properly used, thermography can reveal not only the liquid/gas interface, but also sludge buildup and floating materials such as waxes and foams. Similar techniques can be used to locate levels and bridging problems in silos containing fluidized solids. This paper discusses the parameters and limitations that must be addressed, shows techniques that can be employed, and illustrates the discussions with numerous thermal images.

One-way for a utility to deliver a superior product is for it to use infrared thermography (IR) as a preventative maintenance (PM) tool in its generating stations and on its transmission / distribution (T&D) system. Thermography’s use in a PM program can help avoid emergency restorations, identify additional issues to be addressed during routine maintenance, minimize component deterioration which extends component life cycle, and verify work performed as well as identify bad work practices. All these benefits lead to reduced utility maintenance costs and parts stock, and increased system reliability, utility and customer revenues, and utility customer retention.

An ultra-low-noise readout IC originally designed for low-background imaging when hybridized with indium gallium arsenide (InGaAs) detectors has been combined with indium antimonide (InSb) detectors instead. This novel focal plane array operates in the 3-5 micron waveband and is capable of imaging the very low backgrounds encountered at extremely short exposure or integration times. Combining the FPA with specialized support electronics that enable precision triggering has resulted in a commercially-available camera system that can take stop-motion thermal images of explosions, supersonic bullets and other fast projectiles without the need for rotating mirrors or other optomechanical assemblies that are required in a scanning or streak camera system. The camera system can be easily calibrated to measure the in-band radiance of these objects, as well as enabling estimates of their surface temperature based on laboratory measurements of emissivity.

Infrared (IR) techniques can accurately measure temperatures with high spatial resolution, on the order of a few microns resolution. In microelectronics, however, a device’s hot spot, the junction temperature, is a small fraction of a micron. Accurate prediction of junction temperature is critical for reliability and thermal management. This paper presents an accurate closed form model for the junction temperature as a function of device geometry. Based on knowledge of the temperature profile it is possible to reverse the averaging inherent in the IR measurement and obtain the junction temperature accurately based on IR microscopy. This paper illustrates this approach for the case of field effect transistors (FETs) and applies it to several actual measurements.

In the present paper we describe a novel method for scoring polygraph tests using thermal image analysis. Our method features three stages: image acquisition, physiological correlation, and pattern classification. First, we acquire facial thermal imagery using an accurate mid-infrared camera. Then, we transform the raw thermal data to blood flow rate data through heat transfer modeling. Finally, we classify the subject as deceptive or non-deceptive based on the nearest-neighbor classification method. We perform our analysis on the periorbital area of the subjects’ faces. Our previous research has indicated that the periorbital area is the facial area affected the most from blood flow redistribution during anxious states. We present promising experimental results from 18 subjects. We henceforth anticipate that thermal image analysis will play an increasingly important role in polygraph testing as an additional scoring channel. Our ultimate objective is to increase the accuracy and reliability of polygraph testing through the fusion of traditional invasive 1D physiological measurements with novel non-invasive 2D physiological measurements.

This paper presents preliminary results of the project brought up with aim to verify the hypothesis that small, nocturnal rodents use common paths which form a common, rather stable system for fast movement. This report concentrates on results of merging uniquely good detecting features of modern IR thermal cameras with newly elaborated software. Among the final results offered by this method there are both thermal movies and single synthetic graphic images of paths traced during a few minutes or hours of investigations, as well as detailed numerical data of the ".txt" type about chosen detected events. Although it is to early to say that elaborated method will allow us to answer all ecological questions, it is possible to say that we worked out a new, valuable tool for the next steps of our project. We expect that this method enables us to solve the important ecological problems of nocturnal animals study. Supervised, stably settled area can be enlarged by use of a few thermal imagers or IR thermographic cameras, simultaneously. Presented method can be applied in other uses, even distant from presented e.g. ecological corridors detection.

Spectral selection is a powerful technique for enhancing standard infrared imaging systems that have sensitivity over a broad range of the infrared spectrum. The uses of enhanced systems include imaging objects that typically appear transparent to a standard broadband IR imaging system, or to image through materials that would typically appear opaque. Spectral selection can also be used to detect the presence of various chemical species, and to measure their concentration in the atmosphere, or in liquid and solid materials. Spectral selection can be achieved through the use of filters or through the use of a filtered illumination source. This paper briefly describes various applications for imaging cameras based on InGaAs, InSb, and QWIP focal plane arrays in conjunction with filters that are both fixed and tunable.

In the last decade, a technology of thermal imagers was developing on the basis of new infrared detectors, as well for civil and military uses. These imagers implement miniaturised infrared detectors laid out in a matrix placed in the optical focal plane of the imager. The technology of the FPA associates the detector matrix to specific electronics allowing detection and addressing on each pixel. This technology allowed a fast improvement of the performance of the thermal imager. Nevertheless, their use in thermography measurement requires some metrological care. The principal problem is both the uniformization of the pixel’s response and the temporal stability of this uniformization. The second problem consists in the compensation of the thermal drift. In this paper, we present some practical solutions developed by CEDIP infrared systems to perform non uniformity and thermal drift corrections. Performance and limits are reviewed.

Since its introduction less than a year ago, many camera products and end-user applications have benefited from upgrading to the revolutionary BAE Systems MicroIR^TM SCC500^TM Standard Camera Core. This flexible, multi-resolution, uncooled, vanadium oxide (VO_x) microbolometer based imaging engine is delivering higher performance at a lower price to diverse applications with more unique requirements than previous generations of engines. These applications include firefighting, surveillance, security, navigarion, weapon sight, missile, space, automotive and many others. This paper highlights several cameras, systems, and their applictiaons to illustrate some of the real-world uses and benefits of these products.

Current efforts at Lawrence Livermore National Laboratory in the area of vibrothermography (VibroIR or SonicIR) are presented. The primary goals of the efforts of the NDE group at LLNL have been to demonstrate the applicability of vibrothermography to new areas, to examine the degree to which VibroIR may replace existing NDE inspection procedures, and to conduct research on the underlying processes and optimal parameters in its implementation. We report three new applications of VibroIR, in the areas of brazed tube joint inspection, evaluationtion of thick multilayer carbon/carbon composites as used in the NASA Shuttle, and the inspection of soft composite materials. The goal of the brazed joint inspection process is ultimately the replacement of a current dye penetrant inspection procedure. Therefore a direct comparison between VibroIR and dye penetrant inspection is made. Preliminary results of the analysis of a leading edge panel from a NASA Shuttle is also reported as an example of the application of VibroIR to thick composites. Finally, a comparison betweeen the effectiveness of VibroIR versus a spectrum of other NDE techniques (ultrasonic imaging, radiographic tomography) for the imaging of known ceramic defects is briefly discussed.

Sonic IR has shown potential as a viable nondestructive inspection technique for crack detection by demonstrating that clearly identifiable signals can be generated where known cracks exist in certain structures1,2. However, before a technique can be used in a field environment, the factors that affect the reproducibility of the technique must be evaluated and their effect on the results of the technique understood. This will enable the control of these factors in the execution of an inspection procedure at, for example, an Air Force Depot Maintenance facility. In this program, sponsored by the Air Force Research Laboratory, we are taking a Design of Experiments (DoE) approach to determine the effect of several key variables on the results obtained from Sonic IR testing. A set of small samples with known fatigue cracks was tested according to a statistically designed test matrix. The design of this test matrix, the experimental setup, the test results, and conclusions will be presented.

Sonic, or thermosonic nondestructive testing, which is based on the vibrothermography method introduced in the late 1970’s, has attracted a great deal of recent interest as a means for detection of cracks that were previously considered to be undetectable using thermographic inspection methods. Excitation of a solid sample with bursts of high-energy (500 - 3000 Joule), low-frequency (10 - 50 kHz) acoustic energy has been demonstrated to be effective in generating transient localized heating at crack sites, making them detectable by an infrared camera. Despite the apparent simplicity of the scheme, there are a number of experimental considerations that can complicate, or in some cases even prevent, the implementation of vibrothermography-based inspection. Factors including acoustic horn location, horn-crack proximity, horn-sample coupling, and effective detection range all significantly affect the degree of excitation (or whether any excitation occurs at all) that occurs at a crack site for a given energy input. In cases where the experimental objective is precise measurement of crack length, the method used to visualize the data from the IR camera and its optic must also be taken into consideration.

Several data processing techniques were applied to the inspection of a glass fiber composite reference sample. A statistical data comparison was performed to illustrate that the choice of an optimal sequence of processing algorithms depends on the type of prevailing noise and on whether all possible or only particular defects are to be detected.

In the last few years, several quantitative inversion methods have been proposed to analyze pulsed phase thermographic data: statistical methods [1], Neural Networks [2] and wavelets [3], with a wide range of reported accuracies. In the present paper a new approach is proposed based on absolute phase contrast computations defined in a similar way as for absolute temperature contrast [4]. Phase contrast data is then used to estimate the blind frequency, i.e. the frequency at which the defect becomes visible for the 'first' time [5]. It was found an excellent agreement between defect depth z, and the corresponding blind frequencies f_b. Experimental tests on Plexiglas and aluminum specimens demonstrate the potential of the technique on retrieving the depth of flat-bottomed holes. We also discuss temporal aliasing and its relationship with the phase delay images. As will be stressed, the unavoidable differences between the Continuous and the Discrete Fourier Transform of a time-dependent temperature decay signal can be effectively minimized not only by selecting a sampling frequency rate according to Shannon's Sampling Theorem (as is well-known [6]), but also by choosing an appropriate truncation window size [7].

Pulse thermography has been developed by several researchers as one of effective quantitative thermographic NDT techniques. The interest of the researchers has been focused on how to process transient temperature data after pulse heating to conduct successful identification of defect parameters such as its depth, shape and size. In this paper, a simple thermographic NDT technique termed "Rmax method" is proposed, in which the maximum value of the temperature rise ratio is related to the defect depth. The feasibility of the proposed technique is examined in the quantitative identification of the remaining thickness of the steel plate with corrosive material loss defects. Numerical and experimental investigations were made to obtain the relationships between R_max and remaining thickness ratio. It was found that the relationship between R_max and remaining thickness ratio was independent of material’s thermal properties. It was also found that the relationship between R_max and remaining thickness ratio was not influenced by the size of corrosive material loss defect when the thickness of the plate was thin enough compared to the size of defect. The practicability of the present technique was examined for quantitative identification of actual material loss defects appeared on backside of the steel automobile panel.

The thermal line scanner has proven to be a successful method of rapidly scanning large areas of aircraft fuselage for delaminations and metal pipes for corrosion. The limitation of this technique is with the finite depth by which flaws can be located due to the fixed distance that the thermal camera follows the moving line source. To identify deeper flaws within a material, the thermal imager and line source must have a greater separation distance so that the heat has more time to propagate through the material. Ultimately, one would want to identify flaws at any depth requiring continual scans with greater separation between the line source and imager. The Thermal Photocopier is a hybrid of the thermal line scanner. It utilizes a moving line source and a stationary infrared camera. Any one image captured by the computer shows the sample in gradient cooling due to the moving heat source. An algorithm has been developed that reconstructs full-field images of the material at specific cool down times. These frames represent various depths into the sample as the heat propagates through the thickness of the material. Therefore, an object can be analyzed from the front to the back surface for flaws using this modified thermal detection system. This system has been tested on aluminum and composite materials of varying thickness yielding results consistent with thermographic images obtained with flash and quartz lamps.

Quantitative thermal diffusivity and thickness images can be obtained by minimizing the squared difference between the data and a thermal model. This requires the transient portion of the thermal response to be adequately sampled. For fixed infrared camera frame rates (typically 60 hertz) this may be difficult for very fast thermal transients. The focus of this work is to investigate a technique where the application of the flash heat is controlled by a variable delay. By cycling the flash heating and implementing a linearly increasing delay, thermal transients faster than the frame rate of the thermal camera can be successfully sampled. Detection of subsurface defects with improved defect contrast and spatial resolution on samples with fabricated defects is presented.

Laser welds in light-weight transit bus panels were studied by IR imaging. The corrugated structural panels were made from 3mm thick stainless steel. The panels were welded by a high power laser with lines of equally spaced 1” stitches. After discovering problems by visual and tapping inspections, the panels were sent to our laboratory for further investigation. The IR thermography method was chosen to study the welds because of its non-contact nature and potential for large area, high-speed inspections. We used thermophysical properties of the panels and finite element modeling to predict temperature variations of “good” and “bad” welds. Surface heating and “heat leak” methods were used to inspect each weld. The IR images clearly showed characteristic temperature signatures of “good” and “bad” welds. We also discovered a number of partial welds and questionable welds. In the follow-up destructive inspection, the welds interfaces were imaged and related to the infrared images. None or partial penetrations were found on a number of bad and partial welds. Even in the good welds, the weld stitch appeared to be discontinuous. This study helped the bus manufacturer to assess their welding process and make necessary improvement.

Transient thermography is well established as a capable tool for non-destructive testing (NDT) in aerospace composite structures (see for example Favro, et. al 1995). The basic process involves altering the steady state thermal condition of a structure by adding or removing thermal energy (heat) and then observing the transient temperature patterns on a surface by means of a sensitive infrared imaging system. Many techniques for heat addition have been tried including most commonly convective and radiative transfer to external surfaces. As an NDT technique it is especially appealing for composite structures whose constituent thermal properties may vary considerably leading to interesting and illuminating transient patterns (Favro, et. al. 1993). We have developed a novel application of transient thermography with an application to detecting bonding flaws in boron/epoxy skinned aluminum honeycomb composite structures as found for example in the F14 and F15 aircraft. The technique described below uses induction to selectively heat the structure near the flaw region and has potential benefits in a range of applications.

The necessity for more efficient and cost effective aircraft has led in the development of innovative testing and evaluation techniques. Smart and cost effective methods for evaluating the integrity of aircraft structures are necessary to both reduce manufacturing costs and out of service time of aircraft due to maintenance. Nowadays, thermal non-destructive testing and evaluation (NDT & E) techniques are frequently used in the effective assessment of composites. Such techniques are non-contact; the investigated material is heated or cooled by an external stimulus source (flash lamps, air gun, etc) and the resulting thermal transient at the surface is monitored using an infrared - thermal camera. This paper presents certain applications of thermal transient techniques relating to the investigation of composites. Different features or defects were studied: (i) notches, delaminations and fibre optics under multi-ply composite patching (bonded with FM73 adhesive film to the surface of Al 2024-T3), (ii) drilling induced defects on multi-ply laminates of HEXCEL AS4/8552 carbon fibre composites and (iii) impact damage on carbon fibre reinforced plastic (CFRP) panels and honeycomb sandwich structures (bonded with AF-163-2U.03 adhesive film). The approaches used in this study, provided first-rate results in all cases.

Infrared thermography is a non-destructive evaluation technique that can be used to identify debonded areas in FRP strengthening systems applied to concrete. This research provides a summary of IR thermography experiments that were conducted on full-scale AASHTO girders strengthened with four different FRP composite systems. Significant findings were that the thickness of the FRP system as well as the material composition strongly influences the ability to detect defects at the FRP/concrete interface. Additional experiments were conducted on small-scale specimens with implanted defects. Results from these experiments indicate that IR thermography is capable of detecting defects under multi-layer FRP composite systems; however the defect signal strength and time to maximum signal vary significantly from single-layer systems.

Two non-contact NDT and E (non-destructive testing and evaluation) techniques were employed in the inspection of quarry Pentelic marble samples; surface profilometry and infrared thermography. The samples were processed with different roughness treatments (i.e. 60, 80, 100, 220, 400 and 600 mesh) and were evaluated in the laboratory. Furthermore, different surface cleaning treatments were applied to a Pentelic marble surface in situ and then representative samples were collected and evaluated in the laboratory by the means of these two non-destructive techniques. Quantitative analysis of all samples was performed. In particular, the surface roughness parameter Rq at a specific length scale and 3-D micro-topography plots were attained by the use of the laser profilometry scanning approach, whilst temperature - time plots displaying the intensity of pixels as a function of time on the obtained thermal images were also obtained with the intention of distinguishing the influence of the applied roughness treatments. Results indicate that these two non-destructive techniques can be used for the assessment of surface roughness.

The earlier developed model of rotating kilns used in cement production is applied to the analysis of the efficiency of external control actions, such as air blowing and water spraying, intended to optimize a refractory internal temperature. These actions might be used for detecting defects in a kiln thermal insulation.

In various studies, thermographic methods have been used to measure thermophysical properties of materials. The most widely used such method is the Parker flash technique for diffusivity measurement, in which the transit time of a heat pulse applied to the front face of a sample of known thickness is measured by observing the temperature at the rear surface. In recent investigations, there has been considerable emphasis on single-sided techniques for materials characterization. Typically, quantitative analysis using a single-sided thermographic approach requires some a priori knowledge about the sample, such as thickness, thermal diffusivity, or perhaps a calibration standard with back drilled holes with known diameter and depth. In fact, in certain cases it is possible to use single side pulsed thermographic data to measure, or at least estimate, properties such as thickness, thermal diffusivity and subsurface feature depth with no a priori information about the sample.

The measurement of thermal diffusivity on bulk samples has been previously performed using techniques which require a modulated point heating of the surface and a movement of the temperature detector or of the heating source to determine the phase shift of the modulated surface temperature at an increasing distance from the heating source. Such a movement must be realized with great accuracy and can be the cause of many experimental difficulties. The method proposed herewith is based on the fact that the modulated heating of a bulk sample on a surface spot gives a phase shift, between modulated temperature and heating source, which only depends on the ratio between the spot linear dimension and the thermal diffusion length. A frequency sweep produces a variation of the thermal diffusion length and a variation of the measured phase shift between 0° and -45°, thus allowing for a static single sided measurement of the thermal diffusivity of the sample.

Ceramic matrix composites (CMCs) are potential materials for high temperature applications in gas turbines. Currently, the main areas of consideration include combustor liners and turbine vanes. Because these components contain stress concentrations, it is imperative that candidate materials be fully assessed concerning behavior related to stress risers. In this study, the stress fields adjacent to machined notch roots were examined for woven SiC fiber reinforced, melt infiltrated SiC matrix composites with a BN interphase, utilizing either Hi-Nicalon^TM fibers or the stiffer Sylramic fibers. The double-edge notched tensile test approach was used for multiple notch sizes. In addition, the materials ability to diffuse stress concentrations by inelastic damage mechanisms was considered. The damage was induced by applying predetermined tensile stresses known to cause matrix cracking. The thermoelastic stress analysis technique (TSA, also recognized as SPATE: Stress Pattern Analysis by Thermal Emission) was utilized to define the stress profile on the specimen surface. TSA is based on the fact that materials experience small temperature changes when compressed or expanded. When subjecting a structure to a cyclic load, a related cyclic temperature profile results. The surface temperature profile, measured with an infrared camera, is directly related to the surface stresses on the structure. The amplitude of the TSA signal is defined to be linearly dependent on the cyclic stress amplitude. Here, results were provided concerning the stress concentration behavior as a function of notch length, damage level, as well as the mean stress during TSA measurements.

The aerospace industry makes large use of aluminum components, which must undergo severe fatigue tests simulating the real loads at which they will be subjected. The problem is that the high thermal diffusivity and the low frequency at which fatigue tests on real components can normally be performed often prevent the achievement of adiabatic conditions, and the attainment of quantitative results. Starting on the study of models involving different kinds of mono-dimensional stress distributions, the temperature attenuation can be evaluated and linked to the phase shift. The result is independent from the load applied and from the material. A computer program has been elaborated to correct non adiabatic TSA results on the base of the relation phase shift - attenuation.

Studies of electronic component stress have typically focused on temperature, humidity, and voltage stress. There has been relatively little emphasis on clock signal frequency stress. This study investigated effects of clock frequency stress on a high performance microcontroller used to control the on-off frequency of LEDs on a printed circuit board. Based on the design specification, several frequency levels between 0 and the terminal clock frequency were selected. Thermal profile samples for each stress level were collected using an infrared camera. The data were then divided into two groups for model development and evaluation. Artificial neural network and statistical regression approaches were used to model thermal profiles for each stress level. Objectives were to (1) explore impact of clock frequency stress on IC functionality, (2) observe heating rate differences under clock frequency stress over time; and (3) predict stress levels using the two approaches. Results indicate that the average prediction error is about 7.9% for the neural network approach and about 23.8% for the statistical regression approach. Future directions include thermal profile modeling using Finite Element Analysis (FEA) and development of robust hybrid analytic and experimental models for microcontroller lifetime prediction.

Thermal signature may be one of the defining factors in determining the applicability of fuel cell auxiliary power unit (APU) technology in military applications. Thermal characterization is important for military applications given that identification and detection may be accomplished through observation of its thermal signature. The operating modes and power takeoff operations of a vehicle will likely determine the thermal profile. The objective of our study was to develop and implement a protocol for quantifying the thermal characteristics of a methanol fuel cell and an idling tractor engine under representative characteristic operations. APU thermal characteristics are a special case for which standardized testing procedures do not presently exist. A customized testing protocol was developed and applied that is specific to an APU-equipped vehicle. Initial testing was conducted on the methanol APU-equipped Freightliner tractor using a high-performance radiometric infrared system. The APU profile calls for a series of infrared images to be collected at three different viewing angles and two different elevations under various loads. The diesel engine was studied in a similar fashion using seven different viewing angles and two different elevations. Raw data collected according to the newly developed methodology provided the opportunity for computer analysis and thermal profiling of both the fuel cell and the diesel engine.

A fiber-optic/infrared (F-O/IR), non-contact temperature measurement system was characterized, and the existing technique for data collection improved, resulting in greater repeatability and precision of data collected. The F-O/IR system is a dual-waveband measurement apparatus that was recently enhanced by the installation of a tuning fork chopper directly into the fiber optical head. This permits a shortened distance between fiber and detector pair, and therefore a stronger signal can be collected. A simple closed box with the inside painted flat black was constructed and used to prevent stray radiation and convection, thus minimizing undesired effects on the measurement process. Analyses of the new data sets demonstrate that system improvements provide a cleaner and more reliable data collection capability. The exponential relationship between detector output voltage and object temperature indicates that the instrument is operating within its nominal range. The overall goal of this project was to develop a reliable technique to measure the temperature of Kapton HN, an aluminized polymer material being studied for potential future NASA missions. A spectral model that emulates the instrument was also developed in this study. Our measurements and characterization of KaptonÒ HN will be incorporated into the spectral model in order to determine the sensitivity of the instrument to background radiation, spectral emittance of Kapton HN, and other parameters that may affect thermal measurements.

In the current context of increased surveillance and security, more sophisticated surveillance systems are needed. One idea relies on the use of pairs of video (visible spectrum) and thermal infrared (IR) cameras located around premises of interest. To automate the system, a dedicated image processing approach is required, which is described in the paper. The first step in the proposed study is to collect a database of known scenarios both indoor and outdoor with a few pedestrians. These image sequences (video and TIR) are synchronized, geometrically corrected and temperature calibrated. The next step is to develop a segmentation strategy to extract the regions of interest (ROI) corresponding to pedestrians in the images. The retained strategy exploits the motion in the sequences. Next, the ROIs are grouped from image to image separately for both video and TIR sequences before a fusion algorithm proceeds to track and detect humans. This insures a more robust performance. Finally, specific criteria of size and temperature relevant to humans are introduced as well. Results are presented for a few typical situations.

Fire fluctuation is caused by internal physic-chemical changing mechanism and variations of external environment. The study of fire fluctuation will help to predict developing tendency of fire and to understand the structure and stability of flame. Several parameters can represent the fluctuation of fire, such as velocity, temperature and optical scattering. The transparency of fire changes with flow state in fire plume. Thus, light attenuation-time history of fire is corresponding to fire fluctuation. A technology utilizing laser-based photoelectric pairs as sensors to measure fire fluctuation in intermittent and smoke zone of a pool fire is described here. In this technique, joint time frequency analysis (JTFA) algorithm is used to determine the frequency change of fire fluctuation during combustion procedure. Ethyl-alcohol and gasoline fire were studied with this technique and the results are presented here. Some limitations of this method are also briefly discussed.

Fine water mist with droplet diameter less than 20 microns is less studied in water mist family used as firefighting agent. Experiments were conducted to study the radiant heat blocking function of fine water mist in suppressing pool fire. The fine water mist was generated by a jet atomizer. The jet flow of mist was with low momentum when it exerted on the pool fire. The interaction of this kind of fine water mist with pool fire is quite different from those mists with large droplet size and momentum. A group of ethyl-alcohol and gasoline pool fires with different power is used in the research. Fine water mist was exerted on the pool fire from different distances. Radiant heat flux was measured before and after the mist application. The experiment results show that because of its small droplet size and low momentum, the fine water mist could not even penetrate the buoyant plum zone of relatively larger scale pool fire. No water mist could reach the surface of the flame and result in no radiant heat blocking function would realize in the flame zone. This function is valid in low power pool fire and this limitation is obtained from the research for the studied pool fire.

The demand for improved radiometric accuracy of the remote sensing instrumentation used for diagnostic applications involving hot gas emission spectroscopy requires regular “in-field” recalibration. The most convenient calibration source for such applications is a large emitting area blackbody capable of operating at temperatures approaching 1000 K which is also compact and portable. NPL in collaboration with the University of Reading have designed and assembled a large emitting area blackbody that meets these requirements. The blackbody design is based on a grooved base that is electrically heated to temperatures up to 1000 K. The base is coated with a high emissivity coating, which does not deteriorate during prolonged heating under atmospheric conditions. This base is enclosed by a specularly reflecting cavity that is water-cooled. Monte Carlo calculations were used to design the shapes of the base and reflective cavity to ensure that despite a cavity depth of 203 mm and a black body aperture diameter of 102 mm, the spectral radiance of the blackbody is known with a 1% uncertainty in the 2.5 μm to 14 μm wavelength range. The presentation will describe the design of the blackbody and the processes used for selecting the black coating of the base and the reflective coating of the specularly reflecting cavity.