Electrical substitution cryogenic radiometer based spectral responsivity scale between 250–2500 nm wavelengths

This paper presents the spectral responsivity scale between 250–2500 nm developed by the National Metrology Institute of Turkey (UME). For that purpose silicon photodiode based trap detector and electrically calibrated pyroelectric radiometer (ECPR) that were calibrated against primary level absolute electrical substitution cryogenic radiometer (ESCR) were used as transfer standards. Using highly collimated and stabilized (10–5) lasers, absolute optical powers and absolute responsivity of trap detector were measured with an uncertainty of the order of 10–4. In visible (VIS) region responsivity scale was set by means of the models for the reflectance and internal quantum efficiency. In the ultraviolet (UV) and near-infrared (NIR) regions spectrally flat (0.1%) ECPR was used.