Characterization of developed integrating sphere photometer system for total luminous flux measurements

This research focuses on characterizing a developed integrating sphere photometer system for measuring total luminous flux at the National Institute of Standards (NIS) in Egypt. The research examines factors such as the efficiency of the integrating sphere across different wavelengths, the sphere photometer calibration factor (SPCF), and temperature variations in the photometer system during measurement days. One setup utilizes a spectroradiometer with an uncertainty of 4.7% and a 2.5-meter integrating sphere to measure the spectral responsivity of the sphere photometer. Another setup involves a 2.5-meter big-integrating sphere and NIS-photometer, along with NIS- luminous flux standard lamps calibrated at (NPL) with an uncertainty of 0.8%, to determine the SPCF. The overall uncertainty of the final (SPCF) ranges from 0.03% to 0.05%, while the temperature variation during measurements ranges from 0.045% to 0.07%.