Via CarbonLighthouse comes an interesting discussion of just how many lumens per watt (LPW) we can theoretically get out of LED emitters. Spoiler: 683. And only at one wavelength, a practical color-changing entertainment fixture will have to contain different types of emitters at different wavelengths and the LPW will necessarily go down.

At last we see the light: a light source that is 555 nanometers in wavelength and that uses one Watt of power and is 100% efficient will produce 683 lumens. Thus the efficacy of such a light would be 683 lumens per Watt.

The discussion gets wonderfully technical, but it’s fascinating.