Luminous flux is measured in lumens (lm) and describes the visible radiant power of light. It indicates how much light a light source emits per second in all directions. The higher the luminous flux of a light source, the brighter it appears. When selecting lamps and luminaires, the luminous flux can be used as a measure of brightness and performance.
Luminous Intensity - Candela (cd)
Luminous intensity is measured in candela (cd) and indicates how much light is emitted from a light source per solid angle. In signalling technology, the proportion of luminous flux that is emitted in a particular direction is taken into account, as this is what gives the signal to the observer. For a household candle, the total luminous intensity is 1 cd.
Illuminance - Lux (lx)
Illuminance is measured in lux (lx) and is the amount of light that falls on a certain defined area. Illuminance indicates how bright or intense the light is on a surface. It depends on the light source, its distance from the surface and the angle of radiation. In contrast to luminous intensity, which is a property of the light source itself, illuminance refers to the illuminated surface.
