Language of Light

2.Concepts

2.2 SPECTRORADIOMETRY

Spectroradiometry is the measurement of light energy at individual wavelengths within the electromagnetic spectrum. It can be measured over the entire spectrum or within a specific band of wavelengths.

2.2.1 SPECTRAL RADIANCE

The radiance of a light source is a single value which is the sum of all energy measured over a spectrum. The individual energy values at a particular wavelength in nanometer (nm) can be determined by a spectral radiance measurement.
The SI units for spectral radiance is Watt/square meter Steradian nanometer (Watt/m2 sr nm).

2.2.2 SPECTRAL IRRADIANCE

This is a measure of radiant flux at particular wavelength incident on per unit area.
The SI units for spectral radiance is Watt/square meter nanometer (Watt/m2 nm).