IEVref:845-21-035ID:
Language:enStatus: Standard
Term: spectral luminous efficiency, <for a specified photometric condition>
Synonym1:
Synonym2:
Synonym3:
Symbol: V(λ), <for photopic vision> <pour la vision photopique>
V′(λ), <for scotopic vision> <pour la vision scotopique>
Vmes;m(λ), <for mesopic vision> <pour la vision mésopique>
V10(λ), <for the CIE 10° photopic photometric observer> <pour l'observateur photométrique photopique 10° CIE>
VM(λ), <for the CIE 1988 modified 2° spectral luminous efficiency function for photopic vision> <pour la fonction d'efficacité lumineuse relative spectrale de 2° pour vision photopique (CIE 1988 modifiée)>
Definition: quotient of the radiant flux at wavelength λm and that at wavelength λ, such that both produce equally intense luminous sensations for a specified photometric condition and λm is chosen so that the maximum value of this quotient is equal to 1

Note 1 to entry: The spectral luminous efficiency of the human eye depends on a number of factors, particularly the state of visual adaptation and the size and position of the source in the visual field. The photometric condition should be specified (e.g. photopic, scotopic, mesopic). If it is not specified, photopic vision is assumed and the symbol V(λ) is used. The values of the V(λ) function have been internationally agreed in 1924 by the CIE (Compte Rendu 6e session, p. 67), completed by interpolation and extrapolation [ISO 23539:2005(E)/CIE S 010/E:2004, Photometry – The CIE System of Physical Photometry], and recommended by the International Committee of Weights and Measures (CIPM) in 1972.

Note 2 to entry: For scotopic vision, the symbol V′(λ) is used. The values of the V′(λ) function were adopted by the CIE in 1951, were published in Compte Rendu 12e session, Vol. 3, p. 37 and in ISO 23539:2005(E)/CIE S 010/E:2004, Photometry – The CIE System of Physical Photometry, and ratified by the CIPM in 1976.

Note 3 to entry: For mesopic vision, the spectral luminous efficiency function is denoted by Vmes;m(λ), where m is a coefficient determined by the visual adaptation level. The values of the Vmes;m(λ) function at representative values of m are given in CIE 191:2010, Recommended System for Mesopic Photometry based on Visual Performance.

Note 4 to entry: The V(λ) function applies at all luminance levels for foveal conditions, i.e. for all on-axis visual tasks (where objects seen by the eye are in a narrow field of view). For visual tasks that are not on-axis, the following specifications are given by CIE 191:2010, Recommended System for Mesopic Photometry based on Visual Performance: Scotopic photometric quantities are applicable to the condition where the eye is adapted to an average luminance of < 0,005 cd·m−2; mesopic photometric quantities are applicable to the condition where the eye is adapted to average luminance levels between 0,005 cd·m−2 and 5 cd·m−2; photopic photometric quantities are applicable to the condition where the eye is adapted to an average luminance greater than 5 cd·m−2.

Note 5 to entry: Considering that the spectral luminous efficiency function of the human eye changes with visual angle, in 2005 CIE adopted the "CIE 10° photopic photometric observer", V10(λ), and recommended it for situations where the eye is fully light adapted and the visual target has an angular subtense larger than 4° or is seen off-axis (see CIE 165:2005, CIE 10 Degree Photopic Photometric Observer).

Note 6 to entry: Considering the discrepancies between the average human spectral luminous efficiency and the V(λ) function, in 1990 CIE adopted the "CIE 1988 Modified 2° Spectral Luminous Efficiency Function for Photopic Vision", VM(λ), and recommended it for applications in visual sciences (see CIE 86-1990, CIE 1988 2° Spectral Luminous Efficiency Function for Photopic Vision).

Note 7 to entry: Photometric quantities are calculated by integrating the product of the radiometric quantity by the spectral luminous efficiency function and then multiplying by the maximum of the stated spectral luminous efficacy function, with the integral being taken across the full optical radiation spectrum. For example, for the CIE standard observer for photopic vision, the luminous flux of a source with spectral radiant flux Φe,λ(λ) is expressed by

Φ v = K m 0 Φ e,λ (λ) V(λ)dλMathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgaruWqVvNCPvMCG4uz 3bqee0evGueE0jxyaibaieYdi9WrpeeC0lXdh9vqqj=hEeea0xXdbb a9frFj0=OqFfea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXd bPYxe9vr0=vr0=vqpWqaaeaaciWacmGadaGadeaaeaGaauaaaOqaai abfA6agnaaBaaaleaacaqG2baabeaakiabg2da9iaadUeadaWgaaWc baGaaeyBaaqabaGcdaWdXbqaaiabfA6agnaaBaaaleaacaqGLbGaai ilaiabeU7aSbqabaGccaGGOaGaeq4UdWMaaiykaiaaysW7aSqaaiaa icdaaeaacqGHEisPa0Gaey4kIipakiaadAfacaGGOaGaeq4UdWMaai ykaiaaykW7caqGKbGaeq4UdWgaaa@5301@

where Km ≈ 683 lm·W−1 (see also "maximum luminous efficacy").

Note 8 to entry: The spectral luminous efficiency has unit one.

Note 9 to entry: This entry was numbered 845-01-22 in IEC 60050-845:1987.


Publication date:2020-12
Source
Replaces:
Internal notes:
CO remarks:
TC/SC remarks:
VT remarks:
Domain1:
Domain2:
Domain3:
Domain4:
Domain5: