Lichtflusses

Lichtfluss is a German term that translates to luminous flux in English. It is a measure of the total quantity of visible light emitted by a light source per unit of time. Luminous flux is measured in lumens (lm). The lumen is the SI derived unit for luminous flux. It is defined as the luminous power of light that is emitted from a source in all directions into a solid angle of one steradian, and that has a frequency of 540 x 10^12 Hz. Essentially, it quantifies how bright a light source appears to the human eye. Factors such as the spectral power distribution of the light source influence the perceived brightness, even if the total radiant flux (measured in watts) is the same. Different types of light sources, like incandescent bulbs, LEDs, and fluorescent lamps, will have different lumen outputs for the same power consumption. When comparing light bulbs or other light sources, lumen output is a more relevant metric for determining overall brightness than wattage alone, especially with the advent of energy-efficient lighting technologies.