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

AI Thread Summary
The discussion centers on converting lumens to radiant flux in Watts for visible LEDs, as the user seeks a method to standardize measurements across different wavelengths. They reference the standard luminosity function and express a desire for a tool or program that facilitates this conversion. A key point mentioned is that a lumen is defined as 1/683 Watt at 555 nm, highlighting the challenge of using different units in lighting versus radio engineering. The user plans to derive values from blue to near-infrared (NIR) wavelengths and share their findings with the community. The conversation underscores the need for standardized measurement approaches in optical engineering.
Andy Kellett
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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
https://en.wikipedia.org/wiki/Luminosity_function
but was hoping someone knew of a website or program that already does this.
Thanks!
 
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Andy Kellett said:
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
https://en.wikipedia.org/wiki/Luminosity_function
but was hoping someone knew of a website or program that already does this.
Thanks!
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.
 
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tech99 said:
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.

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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