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quotient of transmitted radiant flux, Φt, and incident radiant flux, Φm

Note 1 to entry: Transmittance is also defined spectrally in terms of wavelength, in which case, "spectral" is added before the quantity name.

Note 2 to entry: Due to energy conservation, α + ρ + τ = 1 except when polarized radiation is observed, where α is absorptance and ρ is reflectance.

Note 3 to entry: Transmittance, τ, is the sum of regular transmittance, τr, and diffuse transmittance, τd: τ = τr + τd.

Note 4 to entry: The transmittance has unit one.

Note 5 to entry: This entry was numbered 845-04-59 in IEC 60050-845:1987.

Note 6 to entry: This entry was numbered 17-1337 in CIE S 017:2011.

Publication date: 2020-12
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