Emissivity is a fundamental property of materials which is an important parameter to determine the accuracy of measurement of temperature by radiation thermometers.
In this study, emissivity of copper is measured by radiomatric emissivity methods and this method makes the large error of emissivity when the real temperature is measured by radiation thermometers, which is brought on imperfection of internal blackbody cavity in the sample.
However, when the real temperature is measused by reference thermocople, the measured value of emissivity are in agreement with those of earlier studies.
The measured spectral emissivity of copper with polished surface is 0.105 ± 0.004 at effective wavelength 650 nm, which increases to 0.7 as oxidizing and spectral emissivity at effective wavelength 910 nm is 0.031 ± 0.005. The dependence of emissivity on temperature is not detected on temperature range of 800-1000℃. The spectral emissivity at effective wavelength 2.9㎛ is linearly increasing with temperature. The measured emissivity is 0.04(at 700℃) with temperature coefficient $1 × 10^{-5}/℃$, which is larger than calculated value.
The emissivity of rough surface larger than that of polished because of increase of diffuse reflection.
