Cavity emissivity of fixed-point blackbody

This paper describes a study of the effective emissivity of different design cavities for fixed-point blackbodies. Cavity reflectivity was measured by using a laser, an integrating sphere and a white diffuse plate as a reference. The intrinsic emissivity of the graphite was estimated as 0.89. The difference of cavity emissivity was compared to the difference in the radiance at the freezing point.