Measuring temperatures on absorbers irradiated in a solar furnace by flashassisted multi-wavelength pyrometry (FAMP)

In a solar furnace, the sample is heated by concentrated solar radiation of which a certain fraction will be reflected. If the thermal (Planckian) emi ssion of the sample shall be used to measure its surface temperature one ha s to either separate the thermally emitted from the reflected radiation or to make sure that the reflected solar radiation is negligible compared to t he emitted thermal radiation. Furthermore, the accuracy of radiation thermo metry significantly relies on an accurate knowledge of the sample emittance which generally depends on wavelength as well as on temperature. In this p aper, we propose a multi-wavelength analysis for the separation of emitted and reflected radiation and the use of an additional flash to probe the spe ctral emittance. We first outline the basic ideas and discuss their limitat ions. We then show experimental and numerical results and add some comments addressing the possibility of avoiding the need for a flash.