Development, and uncertainty evaluation of luminous flux integrating sphere photometer system at NIS-Egypt

The description in detail of the developed luminous flux (lumen) system based on 2.5 meters integrating sphere at the National Institute of Standards (NIS) is presented. The developed system consists of a two and half-meter integrating sphere, a LMT photometer, a precise and stable power source, and standard references luminous flux sources. The description of the system is described and the uncertainty budget of the measurements is evaluated. The uncertainty estimation reveals that the relative expanded uncertainty (k=2) of 1.49 % including the standard lamp uncertainty. According to the evaluation results that carried out between the two NIS's systems, of the integrating sphere and goniophotometer, the ratio of the measured luminous flux value of the integrating sphere to that of the goniophotometer was 1.01 with an expanded uncertainty (k=2) less than,1.5 %. All the system's instrument has been developed and controlled by the LabVIEW PID algorithm program.