Yes, it is possible to convert illuminance to irradiance for a single wavelength if you have the necessary information. Illuminance and irradiance are related quantities that measure the amount of light falling on a surface, but they are defined for different scenarios.
Illuminance (measured in lux) refers to the amount of light incident on a surface, taking into account the sensitivity of the human eye to different wavelengths. It is weighted by the photopic luminance function, which represents the spectral sensitivity of the human eye under well-lit conditions. The photopic luminance function is typically represented by the CIE (International Commission on Illumination) V(λ) curve.
Irradiance (measured in watts per square meter or W/m²), on the other hand, refers to the power of electromagnetic radiation incident on a surface, typically at a specific wavelength. It represents the total energy arriving per unit area and is not weighted by the human eye's spectral sensitivity.
To convert illuminance to irradiance for a single wavelength, you would need to know the following information:
- The illuminance value for the specific wavelength, given in lux.
- The photopic luminance weighting at that wavelength, represented by the CIE V(λ) curve.
Once you have these values, you can use the following formula to perform the conversion:
Irradiance (W/m²) = Illuminance (lux) / [V(λ) × K],
where V(λ) is the photopic luminance weighting at the given wavelength, and K is a constant that converts lux to watts per square meter.
Please note that the specific value of the constant K depends on the wavelength and the units being used, so you would need to consult appropriate references or standards to determine the correct value for your specific case.