nit (nt)

[3.5.8]  (See SI unit of luminance.)

luminous efficacy of a source

[3.11] The total emitted luminous flux divided by the total source electrical input power; expressed in lumens per watt (lm/W). Note 1: The term luminous efficacy can be applied to […]

CIE scotopic luminous efficiency function

[3.10.3] V’ (Λ) The spectral luminous efficiency function for scotopic vision, adopted by the International Commission on Illumination (CIE) in 1951. (See Table T-7.) NOTE: This term and its definition […]

CIE photopic luminous efficiency function

[3.10.2] V(λ)   The spectral luminous efficiency function for photopic vision.  It was adopted in 1924 by the International Commission on Illumination (CIE) and in 1970* by the International Committee […]

spectral luminous efficiency of radiant flux

[3.10.1] The ratio of the luminous efficacy for a given wavelength to the value at the wavelength of maximum luminous efficacy. It is dimensionless. Note: The term spectral luminous efficiency […]