Abstract
A recently assembled setup to measure the spectral emissivity at elevated temperatures above 1000 K is described in detail. It is based on a commercial laser-flash apparatus, which has been substantially modified to measure both the laser pulse energy—leading to the pulse heating of the specimen—and the resulting temperature rise. For these measurements the laser beam was characterized with respect to its spatial energy distribution. The temperature rise itself is detected by a specially designed, fast-response radiation thermometer with a spectral responsivity at the wavelength of the laser radiation of 1064 nm. Additional corrections have been investigated to correct the measured temperature radiation for the influence of the hot surrounding furnace. Also, the non-adiabatic temperature rise is corrected with a for the measurement of the thermal diffusivity established fitting function. First measurement results for the normal spectral emissivity of isostatic-pressed graphite between 1000 K and 1800 K are presented.
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