During fabrication, LEDs grow in the form of a crystal wafer. A 2-inch diameter wafer can carry more than 20,000 LED chips. Colour and intensity variations are common across a wafer.

Black Body Radiation

All matter emits electromagnetic radiation when it has a temperature above absolute zero. A perfect black body is in thermal equilibrium with its surroundings.

CAD (Computer Aided Design)

An abbreviation used to describe the creation of models to represent 3D objects and their associated drawings. See IGES and STEP file formats.


The SI base unit of luminous intensity which is the power emitted by a light source in a particular direction, weighted by the sensitivity of the human eye.


An optical system that uses both reflection and refraction of light. E.g.

CCT (Correlated Colour Temperature)

The temperature of the black-body radiator whose perceived colour most closely resembles that of a given stimulus at the same brightness and under specified viewing conditions.

CIE Chromaticity Diagram

In 1931 (Commission Internationale de l’Eclairage (CIE) established the X-Y-Z tristimulus system for measuring colour properties, based on the assumption that every colour is a combination of three

Colour Mixing Lens

A colour mixing lens uniformly mixes the light of different colour LEDs into a single colour which is the resulting combination.

Colour Over Angle (COA)

Colour Over Angle (COA) is a term to define the variations in colour of light over angular displacement.

CRI (Colour Rendering Index)

A number on a scale 0-100 that represents the ability of an artificial light source to reproduce how the colours in an object look compared to an ideal light source, e.g. day light CRI = 100.

Daily Light Integral (DLI)


Total amount of PAR that lands on a square meter surface per day.

Dominant Wavelength (λd)

A measure of the hue sensation perceived by the human eye.