Acquisition Of Thermal Images Research Articles

Flexible hollow optical fiber bundle for infrared thermal imaging

A flexible and coherent bundle of hollow optical fibers was fabricated for infrared thermal imaging. For acquisition of thermal images, differences in the transmission efficiency among the fibers were numerically compensated to obtain high temperature resolution of 1°C for measuring body temperature. In a lens system with 10-fold magnification and hollow fibers of 320-μm inner diameter, the spatial resolution is around 3 mm. The hollow-fiber bundle enables observation of the surface temperature of inner organs and blood flow of the surfaces when the bundle is introduced into the human body with an endoscope.

Flexible hollow optical fiber bundle for infrared thermal imaging

A flexible and coherent bundle of hollow optical fibers was fabricated for infrared thermal imaging. For acquisition of thermal images, differences in the transmission efficiency among the fibers were numerically compensated to obtain high temperature resolution of 1°C for measuring body temperature. In a lens system with 10-fold magnification and hollow fibers of 320-μm inner diameter, the spatial resolution is around 3 mm. The hollow-fiber bundle enables observation of the surface temperature of inner organs and blood flow of the surfaces when the bundle is introduced into the human body with an endoscope.

Passive infrared thermographic imaging for mobile robot object identification

AbstractThe usefulness of thermal infrared imaging as a mobile robot sensing modality is explored, and a set of thermal–physical features used to characterize passive thermal objects in outdoor environments is described. Objects that extend laterally beyond the thermal camera's field of view, such as brick walls, hedges, picket fences, and wood walls, as well as compact objects that are laterally within the thermal camera's field of view, such as metal poles and tree trunks, are considered. Classification of passive thermal objects is a subtle process because they are not a source for their own emission of thermal energy. A detailed analysis is included of the acquisition and preprocessing of thermal images, as well as the generation and selection of thermal–physical features from these objects within thermal images. Classification performance using these features is discussed, as a precursor to the design of a physics‐based model to automatically classify these objects. Published 2009 Wiley Periodicals, Inc.*This article is a US Government work and, as such, is in the public domain of the United States of America.

Evaluation of different approaches for estimating and mapping crop water status in cotton with thermal imaging

Canopy temperature has long been recognized as an indicator of plant water status, therefore, a high-resolution thermal imaging system was used to map crop water status. Potential approaches for estimating crop water status from digital infrared images of the canopy were evaluated. The effect of time of day on leaf temperature measurements was studied: midday was found to be the optimal time for thermal image acquisition. Comparison between theoretical and empirical approaches for estimating leaf water potential showed that empirical temperature baselines were better than those obtained from energy balance equations. Finally, the effects of angle of view and spatial resolution of the thermal images were evaluated: water status was mapped by using angular thermal images. In spite of the different viewing angles and spatial resolution, the map provided a good representation of the measured leaf water potential.

Defect detection of concrete structures using both infrared thermography and elastic waves

There are many nondestructive testing techniques that can be applied to assess the condition of existing concrete structures with little expenditure of human labor. The objective of the current research is to pilot-study how one can combine active infrared thermography (IRT) with elastic wave techniques. In such a manner, the fast scanning of a large structure is followed by elastic wave probing at a given small area. Concrete slabs with embedded defects are heated by means of lamps prior to acquisition of thermal images. The thermal images recorded show clear indication of hidden defects of various depths and areas. At present, the results of IRT provide only limited quantitative information regarding the depth of hidden defects in concrete. Depth of defects is readily deduced based on spectral analyses of received elastic wave signals. The fusion of information gathered from IRT and elastic waves provides effective and efficient means for inspection of the building exterior.

Infrared thermographic SAR measurements of interstitial hyperthermia applicators: errors due to thermal conduction and convection

Thermal conduction and convection were examined as sources of error in thermographically measured SAR patterns of an interstitial microwave hyperthermia applicator. Measurements were performed in a layered block of muscle-equivalent phantom material using an infrared thermographic technique with varying heating duration. There was a 52.7% reduction in maximum SAR and 75.5% increase in 50% iso-SAR contour area for a 60-s heating duration relative to a 10-s heating duration. A finite element model of heat transfer in an homogeneous medium was used to model conductive and convective heat transfer during the thermographic measurement. Thermal conduction artefacts were found to significantly distort thermographically measured SAR patterns. Convective cooling, which occurs when phantom layers are exposed for thermal image acquisition, was found to significantly affect the magnitude, but not the spatial distribution, of thermographically measured SAR patterns. Results from this investigation suggest that the thermal diffusion artefacts can be minimized if the duration of the applied power pulse is restricted to 10 s or less.