Improving the Dynamic Emissivity Measurement Above 1000 K by Extending the Spectral Range

To improve the dynamic emissivity measurement, which is based on the laser-flash method, an array spectrometer is characterized regarding its spectral radiance responsivity for a spectrally resolved emissivity measurement above \(1000\,\)K in the wavelength range between \(550\,\)nm and \(1100\,\)nm. Influences like dark signals, the nonlinearity of the detector, the size-of-source effect, wavelength calibration and the spectral radiance responsivity of the system are investigated to obtain an uncertainty budget for the spectral radiance and emissivity measurements. Uncertainties for the spectral radiance of lower than a relative \(2\,\%\) are achieved for wavelengths longer than \(550\,\)nm. Finally, the spectral emissivity of a graphite sample was determined in the temperature range between \(1000\,\)K and \(1700\,\)K, and the experimental data show a good repeatability and agreement with literature data.