Note 1 to entry: Luminous energy for photopic vision is expressed by

$Q_{\text{v}}=K_{\text{m}}{\displaystyle \underset{0}{\overset{\infty }{\int }}{Q}_{\text{e}\text{,}\lambda }}(\lambda )V(\lambda )\text{d}\lambda$

where Q_e,λ(λ) is the spectral radiant energy at wavelength λ, V(λ) is spectral luminous efficiency, and K_m is maximum luminous efficacy.

Note 2 to entry: The term "quantity of light" is no longer used.

Note 3 to entry: Luminous energy can be emitted, transferred or received.

Note 4 to entry: Luminous energy can be expressed by the time integral of the luminous flux, Φ_v, over a given duration, Δt:

${\displaystyle Q_{\text{v}}={\displaystyle {\int }_{\Delta t}{\Phi }_{\text{v}}}\text{d}t}$

Note 5 to entry: The corresponding radiometric quantity is "radiant energy". The corresponding quantity for photons is "photon energy".

Note 6 to entry: The luminous energy is expressed in lumen second (lm·s) or lumen hour (lm·h).

Note 7 to entry: This entry was numbered 845-01-28 in IEC 60050-845:1987.