Application of different metrics for describing light color quality of a white LED

Abstract

Using an example of UV-excited Ca9KMg(PO4)7:1% Eu2+ phosphor, there are described methods for characterizing emitted color quality of light at different operating temperatures. The effect is discussed, of adopting two different colorimetric observers established by the International Commission on Illumination (i.e., the CIE 1931 observer with a viewing angle of two degrees and the CIE 2015 observer with a viewing angle of ten degrees) on the position of a chromaticity point of light emitted by phosphor. It was demonstrated that using the CIE 2015 photometric observer to determine the position of a chromaticity point, the tested phosphor is characterized by smaller changes in the color of emitted light as a function of operating temperature rather than when the CIE 1931 observer is used.