Correlated Color Temperature (CCT):
The actual color of the LED is called the color temperature and is defined in terms of the spectral tri-stimulus values (color coordinates) according to the recommendations of IESNA LM-16. For color coordinates near the blackbody loci, the correlated color temperature, measured in Kelvin (K), is used.
LED stands for light-emitting diode. A diode is an electronic component that allows current to flow in one direction. LEDs pass an electrical current over a semiconductor chip, and that causes the chip to emit a photon or beam of light.
A complete LED lighting unit consisting of a light source and driver together with parts to distribute light, to position and protect the light source, and to connect the light source to a branch circuit.
Lumens (lm) are units of measurement to describe the brightness that comes from a light source, that is equal to the amount of light given out through asolid angle by a source of one candela intensity radiating equally in all directions. The higher the lumens, the brighter the light.
LED lumen maintenance (L70):
The length of time declared by the manufacturer at which 70% lumen maintenance of any large sample of LEDs is reached.
Luminous efficacy is the most commonly used measure of the energy efficiency of a light source. It is stated in lumens per watt (lm/W), indicating the amount of light a light source produces for each watt of electricity consumed.
Color Rendition (CRI):
The effect the spectral characteristic of the light emitted by the LED has on the color appearance of the objects illuminated by it is called color rendition. Color rendering index (CRI) indicates how well a light source renders colors of people and objects, compared to a reference source. This is measured in a scale out of 100.
During fabrication, LEDs grow in the form of a crystal wafer. A 2-inch diameter wafer can carry more than 20,000 LED chips. Color and intensity variations are common across a wafer. LEDs can be “binned” into various groups by wavelength, luminous intensity, voltage drops, and other characteristics.