Uncertainty model and estimation for emissivity of a steel plate with a multi-wavelength pyrometer

A technique was described in which a multi-wavelength pyrometer was used to measure a sample temperature with its short wavelength based on the reflectivity measurement and then to obtain the normal spectral emissivities at longer wavelengths. The normal spectral emisivities of a roughened and slightly oxidized steel plate were measured with this technique at four wavelengths. The standard relative uncertainty of normal spectral emisivities for the sample at 1000°C was less than 2%.