Assessment of Equivalence of the Spectral Radiance Scales following the results of the comparison between the National Metrology Institutes of Korea, China, and Russia

The paper presents the assessment of equivalence of the spectral radiance scales in the wavelength range from 250 to 2500 nm, reproduced at the national metrology institutes of Korea (KRISS), China (NIM), and Russia (VNIIOFI), carried out in the framework of international comparisons. The common set of three tungsten strip lamps was used as an artefact. Based on a series of blind measurements of the lamps spectral radiance performed at each laboratory alternately, the reference value of the comparison was determined at each wavelength as a weighted mean of the measured data of three laboratories. The degree of equivalence of each laboratory was then calculated as the deviation of the measurement data of that participant from the reference value. A data analysis method was proposed for calculating the degree of equivalences and their uncertainties. The method is based on processing spectral radiance ratios, rather than differences, which allows eliminating the influence of a result of one particular participant to results of other laboratories. The comparison results confirm the equivalence of spectral radiance scales of all the laboratories within their expanded uncertainties (k = 2) except a few wavelength points.