# 17-25-115

spectral mismatch correction factor, <for a photometer>

DEPRECATED: colour correction factor

F*

factor by which the readings of a physical photometer can be multiplied in order to correct for the error caused by differences between the relative spectral responsivity of the photometer and the spectral luminous efficiency for photopic vision, V(λ), that it is intended to simulate when the photometer is used to measure a source having a relative spectral distribution different from that of the source with which the photometer was calibrated

Note 1 to entry: Most photometers are designed to simulate the spectral luminous efficiency for photopic vision, V(λ), and are calibrated using a source corresponding to CIE standard illuminant A. For such a photometer, the spectral mismatch correction factor can be calculated using the equation:

where srel(λ) is the relative spectral responsivity of the photometer and S(λ) and SA(λ) are the respective relative spectral power distributions of the source to be measured and CIE standard illuminant A.

Note 2 to entry: The term "colour correction factor" is no longer used.

Note 3 to entry: The term "spectral mismatch correction factor" can also be applied to other detectors whose response is intended to simulate a particular observer function, such as actinic radiometers.

Note 4 to entry: The spectral mismatch correction factor has unit one.

Note 5 to entry: This entry was numbered 17-1224 and 17-205 in CIE S 017:2011.

Publication date: 2020-12