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Backing-out luminosity togo from lumens to radiant flux in W

  1. Jan 6, 2017 #1
    Hi. Has anyone already done the work to back out the standard luminosity function so I can go from lumens at a particular wavelength to radiant flux in Watts? I have visible LED spec sheets with optical characteristics in lumens and I want to calculate the outputs in W. My NIR LED has specs in radiant flux in W because we can't see that. I want everything in W. I found the expression for the standard luminosity function here
    but was hoping someone knew of a website or program that already does this.
  2. jcsd
  3. Jan 7, 2017 #2


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    Wikipedia says a Lumen is 1/683 Watt measured at 555 nm (green).
    What pity illumination engineers do not simply use the same units as radio engineers - Transmitted Power and Isotropic Effective Radiated Power (EIRP) etc.
  4. Jan 9, 2017 #3
    Yes - I know why lighting engineers are concerned with the response of the human eye, but I'm exciting silicon! I will probably just back this out from blue to NIR and share with the group. Thanks for your response and help.
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