The defination of luminous flux,luminous efficacy of a source and luminous intensity

- Dec 26, 2019-

Luminous flux

An optical metric derived from the effect of radiation on a standard photometric observer. In other words, the amount of light emitted per second from the source. Unit: lumen, lm.

The luminous flux represents the ability of the light source to emit light, similar to the flow of the pump. The greater the flow of the pump, the greater the pumping capacity of the pump. Similarly, the larger the luminous flux, the stronger the luminous capacity of the light source.


Luminous efficacy of a source

The ratio of the luminous flux emitted by a light source to the power consumed. Unit: lumen/watt, lm/w.

The luminous efficiency indicates the luminous efficiency of the light source, that is, how much lumen light can be produced for each watt of electrical power provided. This is an index that concerns with energy-saving, the light source with higher efficiency is more energy-saving.


Luminous intensity

The luminous flux radiated by a light source in a unit solid Angle in a specific direction is called the luminous intensity of the light source in that direction, or the intensity of light for short. I'm going to use the symbol I, unit candela, CD

The intensity of the light indicates how bright the source (point source) is and is a characteristic of the source itself, regardless of the distance from the source to the observer. For the same luminaire, the intensity of light in different directions is different. Calculation of company is: I = Φ/W