Measurement of Luminous Intensity Using Filtered Trap Detector

The work described in this paper is a part of the process of lamp and photometer calibration to obtain a new luminous-intensity scale with a lower uncertainty. The procedure and the results of realizing the photometric scale with a standardized detector at the National Institute for Standards (NIS) are described. This method enables photometric values to be derived from absolute spectroradiometric measurements by exact computation. A filtered trap detector has been characterized and used to measure the absolute spectral power distribution of standard lamps. From these data a photometric scale of luminous intensity has been realized. The results were compared to the certified calibration values obtained by National Physical Laboratory (NPL), and showed agreement within uncertainty of ± 1.8%