Understanding Luminous Flux
Luminous flux measures the total quantity of visible light emitted by a source per unit time, weighted according to the human eye's sensitivity to different wavelengths.
Introduction & History
The concept of luminous flux was developed in the early 20th century as part of the field of photometry, which studies the measurement of visible light in terms of its perceived brightness to the human eye.
Key Units
Lumen (lm)
The SI unit of luminous flux, equal to the amount of light emitted per second in a unit solid angle of one steradian by a point source with a luminous intensity of one candela.
Lux (lx)
A derived unit of illuminance, equal to one lumen per square meter.
Practical Applications
Lighting design
Photography
Astronomy
Display technology
Architectural lighting
Key Formula
Luminous Flux Calculation
The luminous flux (Φᵥ) is calculated by integrating the spectral power distribution (Φₑ(λ)) weighted by the luminosity function (V(λ)) over the visible spectrum, multiplied by the maximum luminous efficacy of 683 lm/W.