LED-based standard source providing CIE standard illuminant A for replacing incandescent standard lamps

The calibration scheme for illuminance meters using incandescent standard lamps have long served the industry. However, phasing out of incandescent standard lamps presents difficulties for maintaining calibration schemes. The National Metrology Institutes have received strong addresses for an alternative light source. To address this, an LED-based standard source providing CIE standard illuminant A (Illuminant A standard LED) was developed. The developed standard LED realized an CIE standard illuminant A spectrum using a customized LED package. The spectral distribution mismatch index according to CIE251:2023, was 2.5 %. The aging characteristic after post-assembly was approximately 0.2 % - 0.1 % after 100 h operation, which is superior that of traditional standard lamps. Moreover, the standard LED can be used with actual calibration schemes, and calibrated illuminance meters with sufficient measurement uncertainty for practical use. Illuminant A standard LED have great potential to replace incandescent standard lamps.