Hi How do you get a photon flux per unit wavelength curve for solar radiation? My understanding of "per unit wavelength" is that the wavelengths within a very short range are fired at a detector. The range is then gradually changed to cover higher wavelengths. The values of flux measured by the detector are divided by the size of range. 1) Is this how it works? 2) Also, how do you restrict the solar radiation to lie within a specific "range"? Wouldn't a filter only allow photons of a single wavelength, not range of wavelengths. Thank you.