What compares all the wavelengths of light?

Answer 1

What compares - what do you actually mean? Do you want to measure wavelengths, how much in nm is that light? In that case SPECTROMETER. Do you want to measure energy of certain wavelengths? BOLOMETER

all the wavelengths of light - this is vague to the point of not understandable. All? There is no such machine in the existence, each sup type is for the particular range of wavelengths, because it requires completely different optics