Spectral concentration of radiometric quantity [Spectral radiation intensity of radiance]
The ratio of the radiance in an infinitely small wavelength (frequency) range, Δλ, including the given wavelength (frequency), to this range, Δλ.
The ratio of the radiance in an infinitely small wavelength (frequency) range, Δλ, including the given wavelength (frequency), to this range, Δλ.