4.3 - Emissivity measurement under vacuum in the wavelength range from 4 μm to 100 μm and temperature range from -40 °C to 500 °C at PTB

A new facility of the Physikalisch-Technische Bundesanstalt (PTB) for emissivity measurement under vacuum was brought into operation capable to measure directional spectral emissivity in the wavelength range from 4 μm to 100 μm and temperature range from -40 °C to 500 °C. Here we present the measurement scheme with respect to the spectral radiance of two blackbodies at different temperatures and discuss the evaluation of the emissivity results. We present first results of emissivity measurements under vacuum in the wavelength range from 4 μm to 100 μm and temperature range from -20 °C to 200 °C, compare them with results obtained in air and show that samples with very low emissivity can be measured with sufficiently low uncertainty.