luminous efficiency, <for a specified photometric condition>
V, <for photopic vision>; V′, <for scotopic vision>; Vmes;m , <for mesopic vision>; V10 , <for the CIE 10° photopic photometric observer>; VM , <for the CIE 1988 modified 2° spectral luminous efficiency function for photopic vision>
quotient of radiant flux weighted by the spectral luminous efficiency and the corresponding radiant flux for a specified photometric condition
Note 1 to entry: The photometric condition should be specified (e.g. photopic, scotopic, mesopic). If it is not specified, photopic vision is assumed and the symbol V is used. For other photometric conditions the respective symbol for identification shall be used.
Note 2 to entry: Luminous efficiency for photopic vision is expressed by
where Φe,λ is spectral radiant flux, V(λ) is spectral luminous efficiency, λ is wavelength, K is luminous efficacy of radiation, and Km is maximum luminous efficacy.
Note 3 to entry: The luminous efficiency has unit one.
Note 4 to entry: This entry was numbered 845-01-57 in IEC 60050-845:1987.
Note 5 to entry: This entry was numbered 17-731 in CIE S 017:2011.