Commercially available high power laser diodes can have overall conversion efficiencies of 45% to 50% and research is underway to boost this to a staggering 80%! How do LED compare?
(From: Don Klipstein (Don@Misty.com).) The “Overall luminous efficacy” (lumens out per watt in) is the conversion efficiency (watts out per watt in) times the “luminous efficacy of the emitted light”, and that is 683 (used to be 681) times the photopic function of the emitted light. Photopic function overall is a “weighted average” of the photopic function of every wavelength (or narrow slice of the spectrum), weighted by the amount of optical output at each wavelength or in each little slice of the spectrum. The most efficient (conversion efficiency) visible LEDs to my knowledge are Lumileds “Luxeon” red ones with truncated inverted pyramid dice. At full power, they typically achieve 42 lumens per watt in. The luminous efficacy of the emitted light (lumens out per watt out) is around 160 lumens/watt, maybe a little more. This means the conversion efficiency (watts out per watt in) is around 25%. Lumileds red, orange and yellow LEDs are most efficient when slightly to moderately underp
