Light spectrum for maximum luminous efficacy of radiation and high color quality

To date, many studies on the optimization of the spectral power distributions (SPDs) have been conducted to maximize the energy performance and color quality of white light-emitting diodes (LEDs). Here, not only for LEDs but for any light source, we numerically calculate the SPDs which maximize luminous efficacy of radiation (LER) in function of the color rendering index and of color temperature. As previously reported in the literature, we obtain optimal SPDs that are discrete spectra rather than continuous, but with considerably higher LER values. Such optimal SPDs may be used to design various lighting technologies: incandescent, fluorescent, high-intensity discharge, laser, and solid-state lighting.