An experimental and comprehensive method to measure emission characteristics

The characteristics of emission may be of thermal infrared multispectral processes: either through direct measurements on the emitted flux, which are compared to a reference black body, or through measurements on reflectivity and application of the Kirchoff laws. Both approaches have advantages and drawbacks according to the type of emission characteristics that are studied. The method which is used in this study uses the first principle: it concerns itself with relatively high levels of emissions (greater than 0.5), which are directional and controlled by a given sensor. In order to maximize the precision of measurements, testing respects the following conditions: (1) lessening of residual parasite flux, through the use of low emission materials and a cooled diaphragm, thus creating a confined enclosure; (2) taking into account the residual parasite flux, through models of radiation exchange within the enclosure; (3) assessment of the homogeneity in temperature of both the sample and the reference materials; and (4) calculations on the confidence levels, in function of the variances in the beginning parameters. This use of models, added to technical advances, make it possible to build a very inexpensive test site, at least as far as specific purchases were concerned. Several comparative measurements showed that the range of measurable emissions goes from 0.5 to 1, with an absolute confidence level of 0.05 to 0.02, according to the material. The best performance was obtained when highly emissive and highly heat conductive materials were used.