The measurement of directional spectral emissivity in the temperature range from 80 ºC to 500 ºC at the Physikalisch-Technische Bundesanstalt
Christian Monte and Jörg Hollandt
Dedicated to Wolfgang Buck on the occasion of his 65th birthday
The instrumentation of the Physikalisch-Technische Bundesanstalt (PTB) for the measurement of directional spectral emissivity in air in the temperature range from 80 ºC to 500 ºC and wavelength range from 4 μm to 40 μm is described in detail. Special emphasis is placed on the calculation of the directional spectral emissivity from the measurement results and on the accurate determination of the sample surface temperature. It is shown that even samples with very low emissivity can be measured with sufficient accuracy. An outlook is given for an extension of the emissivity measurement capabilities with a new instrumentation operated under vacuum. It will allow measurements from 0 ºC to 600 ºC and will go into operation by the end of 2009.
Keywords: Emissivity, Emittance, Radiation Thermometry, Radiometry, Radiance, Pyrometry.