The difficulty with pyrometric temperature measurements is that the emissivity must be known. Spectral emissivities, especially of new materials, are often not available and at high temperatures the emissivity varies because of oxidation or other surface reactions.
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The difficulty with pyrometric temperature measurements is that the emissivity must be known. Spectral emissivities, especially of new materials, are often not available and at high temperatures the emissivity varies because of oxidation or other surface reactions.