Valgusvoog

Valgusvoog, known in English as luminous flux, is a photometric quantity that describes the total perceived power of light emitted, transmitted, or received by a light source per unit time. It is measured in lumens (lm) and reflects how bright the light appears to the human eye, rather than the radiant power in watts.

Luminous flux is distinct from radiant flux, which measures actual energy in the electromagnetic spectrum without regard to human visual sensitivity. The relationship is established through the photopic luminosity function V(λ); the luminous flux of a source is obtained by integrating its spectral power distribution with V(λ): Φv = ∫ Φe(λ) V(λ) dλ. The result is the total lumen value reported for lamps and luminaires.

In practice, manufacturers quote the luminous flux to indicate brightness. While higher lumens generally mean a brighter light, perceived brightness also depends on color temperature, beam distribution, and glare. Luminous flux relates to other photometric quantities such as luminous efficacy (lm/W), illuminance (lux, lumens per square meter), and luminous intensity (candela, lumens per steradian).

Measurement and standards are defined under standardized conditions using integrating spheres and calibrated photometers. International guidelines, such as those from the CIE, establish how luminous flux should be measured and reported, ensuring comparability across products and applications.