The characterization of a high-temperature black body as the basis for the NPL spectral-irradiance scale

The paper describes the stabilization and radiometric characterization of a Russian-made high-temperature black body. The black body is actively controlled at around 2500 K, emitting radiation which is stable in radiance to +/- 0,01% at 800 nm, over several hours. Techniques are described which show how the radiance of the black body can be maintained at a constant level from day to day. The techniques used to determine the absolute spectral radiance of the black body using a laser-characterized monochromator are also described.