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 P: 1 I'm trying to find the "Spectral" Illuminance (lux/nm) of a LED in order to find the spectral irradiance (watt/nm). I am somewhat new to optics, especially when it comes to the radiometric and photometric units. I understand that the Lux is just the watt/M^2 scaled to the human eye using the luminous efficacy for each wavelength. I want to know if this method is correct. What I have---- The relative luminosity function (call it L(λ)) lm-1 The total Illuminance from the source (~8 lux) What I think I need to do---- Integrate my L(λ) function multiply by C and set that equal to 8 C is this "normalization" constant (I based this off of the fact that if I have 3 lux of light A and 4 lux of light B on a surface, I will have 7 lux total. In this case A and B are different colours, and I have a full continuous spectrum of them ~350nm-600nm) Then the spectral Illuminance call it S(λ) is just C* L(λ) now I can take this function, C* L(λ) and divide it by the luminous efficacy function η(λ) finally my spectral irradiance function E(λ) is =C* L(λ) / η(λ) Physically this equation incorporates the LED characteristics, the measured light, and the whole lumen/watt : photo/raido metric stuff. Could someone tell me if this is correct and whether or not I missed something? Thanks