Nereus
Enlightened
Moving from Luxeon 3 to Cree XRE we have seen roughly 100% increase in led efficiency: lumens have doubled, keeping watts at the same level. But remember, human eye reacts logarithmically to light intensity. You have to double the lumens to _feel_ the light clearly brighter.
So where are we now? Some 25% of electricity pumped in to led will be transformed to light. One "wow this _looks_ brither" step upwards in efficiency means 50% efficiency. Again second (highly hypothetical...) step like this will take us to the absolute maximum, 100% efficiency.
To sum up, when it comes to the way human eye actually perceives brightness we are only one or two "wow this _looks_ brighter" steps or "lux3 -> Cree XRE" steps from the best possible. That's very close after all!
-N
So where are we now? Some 25% of electricity pumped in to led will be transformed to light. One "wow this _looks_ brither" step upwards in efficiency means 50% efficiency. Again second (highly hypothetical...) step like this will take us to the absolute maximum, 100% efficiency.
To sum up, when it comes to the way human eye actually perceives brightness we are only one or two "wow this _looks_ brighter" steps or "lux3 -> Cree XRE" steps from the best possible. That's very close after all!
-N