Knowledge

Luminous Flux, Unit: Lumen [lm]

Lumen is the measure of the perceived power of light.
luminous intensity, Unit Candela [cd]

The candela is the unit of measurement for luminous intensity and it is used to indicate how bright a lamp is in a given direction.
Illuminance, Unit: Lux [lx]

Lux is the quantity of light or luminous flux incident on a surface to the area of tha surface (πr2).
Luminous Efficcacy, Unit: lm/w

Energy efficiency of light sources is typically measured in lumens per wat (lm/w).
Color Temperature, CCT, Unit: Kelvin [K]

The Color temperature is the specif color shown at a particular temperature. It is normally shown in unit of absoulute temperature, Kelvin [K]...
Color Rendering Index, CRI, [Ra]

Visible Color ↑↓＝CRI [Ra] ↑↓ The criterion here is the color rendering property of a light source. It is called General Color Rendering Index" [Ra].
Beam Angle, Unti: degree

It is the angle between two directions opposed to each other over the beam axis for which the luminous intensity is half that of the maximum luminous intensity...
LED of Wavelength (λ)

Light-Emitting Diodes (LED) differs from others light sources, such as incandescent and flourescent lamps, in the way they generate white light...
Camparison of different lamps sources

Comparison chart of different lamp sources
LED Development

Lumen rating vs. in fixture