Spectral Concentration

The spectral concentration of a quantity characterizing radiation (such as radiant flux or luminous intensity) is the ratio of the quantity in an infinitesimal interval containing the given wavelength λ to the width dλ of the interval. Instead of λ there may be used frequencies, wave numbers, or the logarithms of these quantities. In such cases, the term “spectral concentration” may be made more precise by specifying the quantity used. The graph of the dependence of spectral concentration on wavelength λ or frequency v characterizes the distribution of the quantity in question through the spectrum.