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The Nobel Prize in Physics 2014 is for LED. There is a related Haitz's law:

...every decade, the cost per lumen (unit of useful light emitted) falls by a factor of 10, and the amount of light generated per LED package increases by a factor of 20, for a given wavelength (color) of light.

There are many plots of data (se below), but what are actual formulas describing these data?

I would like to plot those straight lines in Log-scale plot so that years and y-values would correctly appear on the plot.

One of many SOURCEs:

http://www.leapfroglighting.com/better-led-bulbs-and-a-lower-price-its-the-law

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  • $\begingroup$ Looks like pretty good exponentials to me, with exception of the white flux $/Lumen ratio. I would also guess that the exponential part of these curves is almost over. The efficiency of LEDs is getting close to the physics limit and the thermal limit on packages is probably almost maxed out, already. This leaves a reduction in price based on the volume of the manufacturing process, after which the "law" has to saturate. One can guess that the saturation limit can be described by a cost/demand curve from economics, but that's not something that can be derived from physics principles. $\endgroup$
    – CuriousOne
    Oct 7, 2014 at 19:22
  • $\begingroup$ Thanks @CuriousOne I understand this approximately. I would like to plot those straight lines in Log-scale plot so that years and y-values would correctly appear on the plot. $\endgroup$
    – iLie
    Oct 7, 2014 at 19:24
  • $\begingroup$ I would probably digitize the data (google "plot digitizer" or "graph digitizer" for software) and then use a spreadsheet program to re-plot and to do the fit. Excel has a remarkably good fitting algorithm for problems like that. You could, of course, use a lot of more "scientific" tools, if you like. $\endgroup$
    – CuriousOne
    Oct 7, 2014 at 19:32
  • $\begingroup$ @CuriousOne I am looking for simple "rough" relation that relates a year to approximate value and looks like a line in log-plot. JUst a simple rough relation that is the expression of words I quoted from Wikipedia. $\endgroup$
    – iLie
    Oct 7, 2014 at 20:58

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