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 lu minous-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. Th is method enables photometric values to be derived from absolute spectroradiometric measurements by exact co mputation. A filtered trap detector has been charac- terized and used to measure the absolute spectral power distribution of standard lamps. Fro m these data a photometric scale of lu minous intensity has been realized. The results were co mpared to the cert ified calib ration values obtained by Nat ional Physical Laboratory (NPL), and showed agreement within uncertainty of ± 1.8%