Luminous flux

Specifies the total light output from the light source. This quantity is derived from the energy flux (power sent, transferred or received in the form of radiation, the so-called radiant power) on the basis of the degree of its impact on the eye of a normal (reference) observer:

where:

• spectral distribution of the energy flux
• relative spectral luminous efficacy
• luminous efficiency of radiation
• electromagnetic wavelength.