The aim of this paper is to present a nonintrusive and optical method based on the classical thermal radiation laws for the measurement of microscale surface temperature. To overcome the diffraction limit, measurements are performed in the ultraviolet-visible range. According to the Planck’s law, emitting energy is low at these wavelengths and only a photonic flux can be measured through a cooled photomultiplier tube and a photon-counting card. The photonic flux exhibits a random character that can be described through well-known statistic laws such as Poisson or normal distributions. It is shown in this paper that the measured signal (photonic flux) agrees well with these statistics laws and that the surface temperature can be obtained either from the average or/and the standard deviation of the photonic flux. A multispectral technique is also introduced to get rid of the knowledge of the local surface emissivity, which is of particular interest for the measurement of temperature in microscale applications. Finally, temperature measurements carried out on a specific high temperature blackbody developed in our laboratory are compared with those obtained through an infrared camera and allow us to validate our facility and the proposed measurement technique.
This study is part of the general context of thermophysical characterization of liquid metals with an aerodynamic levitation device and laser heating. The density measurements vs temperature of pure and alloyed metals are determined during cooling of the sample. The temperature and shape of the sample are measured, respectively, with a bichromatic pyrometer and filmed by a high-speed camera. The sample visualization is performed by backlighting, which has been preferred to self-illumination. The post-treatment process consists in a binarisation of each recorded image, and then, an ellipse is fitted on the detected edge. The density is directly calculated with the ellipse volume and the sample weight. The good agreement of experimental results on pure metals with the literature validates the method. Then, an industrial steel of unknown liquid density is characterized from 1750 K to 2250 K.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.