Realizations of the units of luminance and spectral radiance at the HUT

Realizations of the units of luminance and spectral radiance at the Helsink i University of Technology (HUT) are presented. These realizations are link ed to HUT units of luminous intensity and spectral irradiance using a chara cterized photometer, a spectroradiometer and an integrating-sphere light so urer. A new method fur determining the spatial uniformity of the output of the integrating-sphere source is described. The uncertainty analysis indica tes a relative expanded uncertainty of 3.6 x 10(-3) (coverage factor k = 2) for the realization of the unit of luminance. The expanded uncertainty for the realization of the unit of spectral radiance varies between 6 x 10(-3) and 2.5 x 10(-2) in the wavelength region 360 nm to 830 nm.