Multi-Spectral Techniques Applied for the Measurement of the Microscale Temperature Through Cooled Multiplier Tube in Photon Counting Mode

The aim of this paper is to present a non-intrusive 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 Photo-Multiplier Tube (PMT) and a photon-counting card. The photonic flux exhibits a random phenomenon that can be well-described through classical statistic laws such as Poisson or Normal distributions. We show in this paper that the signal we measure agrees well with these laws and that the surface temperature can be obtained either from the average or the standard-deviation of the Photonic flux. Multi-spectral techniques based on either physical and optical techniques like monochromatic filters and reflection/transmission diffraction gratings or digital techniques as a Multi-Channel Analyser (MCA) are proposed to get ride of the knowledge of the local surface emissivity. This is of a 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 to validate our facility and the presented measurement techniques.