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Technical environment
Technical environment
Global standard 220V-240V/50Hz-60Hz
Standard for USA/Canada 120V/60Hz, 277V/60Hz
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Luminous flux: light output measured in lumens

Depiction of luminous flux as a measure of luminous output.

Luminous flux is a measure of the light output of a light source

Luminous flux (Φ), measured in lumens (lm), describes the total light output emitted by a light source in all directions. It is calculated from the radiant flux by evaluation with the spectral luminous efficiency of the human eye.

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Luminous flux: depiction of the spectral brightness sensitivity of the human eye for day and night vision

Luminous flux as a photometric quantity indicates the total light output emitted by a light source. In principle, this radiant flux could be specified as emitted energy in the unit watt (W). However, the optical effect of a light source is not adequately described because the emitted radiation is recorded in an indiscriminate way over the entire frequency range and the different spectral sensitivity of the eye is therefore not taken into account.

By including the spectral sensitivity of the eye, the luminous flux is obtained. A radiant flux of 1W emitted at the maximum of spectral eye sensitivity (photopic, 555nm) generates a luminous flux of 683lm. However, the same radiant flux in frequency ranges of lower sensitivity generates correspondingly smaller luminous fluxes according to the V λ curve.

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Further topics on photometry

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