# e-ILV

The e-ILV provides free access to all the terms and definitions contained in the international standard CIE S 017:2020 ILV: International Lighting Vocabulary, 2nd edition.

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# 17-21-074

fluence

He,o; Ho

time integral of spherical irradiance, Ee,o, at a given point over a given duration, Δt

Note 1 to entry: The radiant spherical exposure is the quotient of the radiant energy of all radiation incident on the outer surface of an infinitely small sphere centred at the specified point and the area of the diametrical cross-section of that sphere.

Note 2 to entry: The radiant spherical exposure is the appropriate radiometric quantity for describing a dose for a photobiological or photochemical effect in a scattering medium (e.g. light in skin). It is also the appropriate radiometric quantity for describing the irradiation of microorganisms. The radiant spherical exposure is frequently used incorrectly as a substitute for radiant exposure.

Note 3 to entry: The radiant spherical exposure is expressed in joule per square metre (J·m−2 = W·s·m−2).

Note 4 to entry: This entry was numbered 845-01-45 in IEC 60050-845:1987.

Note 5 to entry: This entry was numbered 17-1028 in CIE S 017:2011.

Publication date: 2020-12