High lumen density sources based on LED-pumped phosphor rods: opportunities for performance improvement

摘要

Recently, LED-based sources with high luminance (10~9 cd/m~2) have been developed. These sources can be applied in projection systems, as well as in other applications requiring high luminance. The technology makes use of a transparent phosphor rod that is pumped by a multitude of blue LEDs. Most of the converted light is guided in the rod towards one of its small sides, where it is extracted using suitable extraction optics. The radiant conversion efficiency (blue flux to converted flux) is presently approaching 0.3. The possibilities for improving this number are discussed. The available phosphor materials emit light in various wavelength regions, ranging from green to yellow and red. These can be used in various light sources, e.g. for DLP and LCD projection.