1, luminous flux φ unit lumen [LM];
Light and the human eye receives energy sum is the luminous flux (φ).
2, light intensity l unit: candela [CD];
In General, the light is in different directions and different intensity. Visible light emission intensity in a particular direction angle is called the light intensity (l).
3, illuminance e units: Lux [LX]; coefficient of the ratio between the luminous flux with the illuminated area.
LX the 1lm distribution of luminous flux average brightness in the area of LM2.
4, luminance l unit: candela/square meter [CD/m2];
Eye see objects reflected light intensity in one direction.
5, the light effect units: lumens per watt [LM/w];
The efficiency of electric energy into light.