HOW WOULD A CIE L STANDARD ILLUMINANT AFFECT MEASUREMENT UNCERTAINTY OF FIELD MEASUREMENTS (PO38, 950-958)

Our aim was to find out how CIE standard illuminant L would decrease the measurement uncertainty of field luminance and illuminance measurements. With help of data of 10 different photometers and 75 spectral power distributions of light sources a large number of spectral mismatch correction factors (SMCFs) were calculated and analysed. Based on preliminary results 10 different light sources were selected as possible calibration sources. 75 light sources were divided into 6 groups: halogen lamps, white LEDs, fluorescent lamps, HID lamps, monochromatic LEDs and natural light sources and for each group 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 by up to 2 %.