Basic lighting terms
Luminous flux
Unit: lumen [lm]
The amount of light emitted by the light source in a unit time is called the luminous flux of the light source.
Light intensity L
The unit - [cd]
The luminous flux emitted by the light source in a given direction is called the luminous intensity of the light source in the direction of the light intensity.
Note: some people use candles to indicate the intensity of light, after 1968 the candle was abolished.
brightness
Unit: Candela per square meter [cd/m2] (Neate (NT) is the name of the old unit of brightness, has now been abolished)
The brightness of a light source in a certain direction is the ratio of the intensity of the light source in the same direction and the surface area of the light emitting surface in the direction.
Note: brightness is the intensity of light. It is a subjective quantity. Different from the brightness, the corresponding amount of the physical definition is the light intensity.
Illumination E
Unit: [lx] lux.
Illuminance is the amount of light transmitted by the light source on the unit area of the object.
Light effect
Unit: lumen / watt (lm/W)
The ratio of the total luminous flux emitted by the light source to the electric power (watt) consumed by the light source is called the light efficiency of the light source.
Color temperature
Unit: Kelvin [K]
When the color of the light source is the same as that of the black body at a certain temperature, the temperature of the blackbody is called the color temperature of the light source. Absolute temperature K (kelvim).
