NPL-CSIC comparison of regular reflectance measurements

A comparison of two different scales of regular reflectance measurements ha s been made between the National Physical Laboratory (NPL, UK) and the Cons ejo Superior de Investigaciones Cientificas (CSIC, Spain). Both laboratorie s have spectrally calibrated a reflectance transfer standard at angles of i ncidence of 8 degrees and 45 degrees in the wavelength range 350 nm to 1000 nm. Relative differences in reflectance are between 2 parts in 10(3) and - 2 parts in 10(3) at 8 degrees, and between 1 part in 10(3) and -4 parts in 10(3) at 45 degrees. These results agree well within their respective uncer tainties.