lumén

Lumén is a proposed photometric unit intended to quantify luminous energy in a time-resolved way. It sits conceptually between lumen, which measures luminous flux, and duration, aiming to express how perceptual brightness accumulates over time. In discussions of dynamic lighting, display technology, or visual ergonomics, lumén offers a framework for comparing sources not just by peak intensity but by sustained perceptual impact.

Origin and naming: The term derives from lumen (light) with a diacritic accent to signal a distinct, time-sensitive meaning. It is used principally in theoretical or design contexts rather than as part of the formal SI system.

Definition: One lumén can be defined as the luminous energy emitted or received per second, equivalently a lumen-second under a given spectral weighting. More precisely, lumén equals the integral over time of the luminous flux weighted by the CIE V(λ) function. Thus lumén is lumen-times-second, representing perceptual energy rather than radiant energy.

Relation to other units: The lumen measures luminous flux (lumens). The lux measures illuminance on a surface. The candela measures luminous intensity. The lumén differs by incorporating time into the quantity, creating a unit for cumulative perceptual exposure. It is not an SI unit and has no formal standard.

Applications and limitations: In theory, lumén could aid in comparing flickering displays, rapidly changing lighting, or visual comfort across devices. In practice, standardization, calibration, and consensus on spectral weighting would be needed before adoption; at present, lumén remains a hypothetical concept rather than a widely used unit.

See also: lumen, lux, candela, photometry, CIE V(λ).