New CIE Standard Illuminant L and its Affect on Measurement Uncertainty

The aim of the research was to find out how proposed new CIE standard illuminant L would influence the measurement uncertainty of photometrical field measurements of luminance and illuminance. With help of data of 10 different photometers and 75 spectral power distributions (SPDs) of light sources a large number of spectral mismatch correction factors (SMCFs) were calculated and analyzed. Based on preliminary results, 10 different light sources were selected as possible calibration sources. For each SPD of considered light sources most suitable calibration source was found together with overall best calibration source which gives SMCFs closest to value 1 for all photometers and light sources. Results show that white LED with CCT close to 4000 K is the best suitable calibration source and its use would in average decrease the measurement uncertainty of field measurements of luminance or illuminance by up to 2 %. The decrease can be noticed at average as well as at very good instruments.