I want to measure the emissivity (or more correctly the absorbtivity) in the wavelength range 1 - 10 micrometer of very hot (~1000 degrees Celcius) ceramic materials. At room temperature this is typically done using an FTIR spectrometer with a gold coated integrating sphere. But for very hot objects the spectrometer would burn! Any ideas of how such emissivity measurement can be performed in a practical, yet accurate, way? I have access to varius furnaces.