Fourier-transform radiation thermometry: measurements and uncertainties.

A Fourier-transform radiometer is used to measure blackbody temperatures in the 5001000-K range. The measurements involve collecting mid-infrared spectra at two known reference temperatures and one unknown temperature. The accuracy of the interpolation measurement technique is discussed, and the effects of the uncertainty in the temperature reference points, the voltage ratio measurement, and the wavelength accuracy are described. Temperature accuracy at the 0.5% level has been achieved; the main uncertainty component is caused by the interferometer drift. Directions to reach 100-mk accuracy levels have been identified.