| Abstract | This intercomparison of spectral responsivity between the National Institute of Standards and Technology (NIST) in the United States and the National Research Council (NRC) of Canada was carried out to test the level of agreement between the two laboratories for routine detector calibrations and also to support the uncertainties quoted by NIST and NRC in appendix C of the Mutual Recognition Arrangement (MRA) drawn up by the International Committee of Weights and Measures (CIPM). The comparison was carried out in two stages: 250 nm to 1100 nm using three silicon (Si) photodiodes, then 700 nm to 1800 nm using two germanium (Ge) and two indium gallium arsenide (InGaAs) detectors. This paper describes briefly the derivation of the spectral responsivity scales, measurement procedures and apparatus used for each laboratory. The results of the intercomparison are presented. In the spectral ranges from 250 nm to 1000 nm for silicon and 750 nm to 1700 nm for germanium and InGaAs, the agreement between the two laboratories is well within the combined uncertainties. In particular, in the 450 nm to 1000 nm spectral range, the agreement is better than ±0.2%. In the 900 nm to 1600 nm spectral range, the agreement is typically ±0.5%. Consequently, the results of this intercomparison are shown to support the uncertainties claimed by NIST and NRC in their routine calibrations, and in their appendix C entries of the MRA. |
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