1. Light

Light is a kind of electromagnetic wave.

Visible light: refers to the part of visible radiation sent from a light source.

The wavelength of visible light: 380nm----780nm

The wavelength of ultraviolet light: 100nm---380nm. It is invisible to human eye.

The wavelength of infrared light: 780nm---1mm. It is invisible to human eye.

2. Colour Temperature / Correlated Colour Temperature (CCT)

Colour temperature is measured by the unit of absolute temperature, K. When the black-body radiator is heated up to different temperatures (kelvin), it will display different colours which vary from red, light red, orange, white, blueish white to blue gradually. By the definition of light colour variation, when the light colour matches that of the black-body radiator at a certain temperature, the absolute temperature of the black-body radiator then is called the correlated colour temperature of the light.


3. Colour Rendering Index (CRI)

It measures the ability of light to reveal the true colours of various objects.

Light with a higher colour rendering index Ra (0-100) produces a colour which is closer to the natural colour.

CRI has 15 colour names: R1 (light greyish red) , R2 (dark greyish yellow) , R3 (dark yellowish green) , R4 (moderate yellowish green) , R5 (light bluish green) , R6 (light blue) , R7 (light violet), R8 (light reddish purple) , R9 (dark red) , R10 (dark yellow) , R11 (dark green) , R12 (dark blue), R13 (white skin colour) , R14 (leaf green) and R15 (yellow skin colour).


3.1、Colour Temperature and Feel


3.2、Bio clock and Light colors


3.3、Effects and applications of CRI


4. Luminous Flux (Lumen Lm)

Lumen, an international (SL) unit of luminous flux, refers to the total amount of light emitted by a light source. (More light emitted, more lumina)

5. Luminous Efficacy
Luminous Efficacy is the efficiency of a light source to convert electric energy to light. Its unit is Lm/W.
6. Average Lifespan

Also known as rated lifetime, it refers to the average lifetime of a lighting product when it works at a rated voltage and current and under a controlled working environment, namely, the lighting hours of lights before half of them are not on.


7. Luminous Intensity

Candela, an international (SL) unit of luminous intensity, refers to the luminous flux within a solid angle emitted by a light source in given direction.