ISO 23946, published in November 2020, defines the absolute quantum efficiency measurement method for LED phosphors used to make white light. This phosphor is a standard phosphor developed by the National Institute of Materials Science (NIMS) in Japan and manufactured in accordance with the ISO 23946 standard. Due to the excellent chemical stability and temperature characteristics of this phosphor, stable emission characteristics can be obtained with almost no change with time. This phosphor can be used to check quantum efficiency measurement results, quality control of optical measuring equipment, quality control of phosphor products, etc.