Is the measure of light falling on a surface, measured in lumens per square metre (lux), and represent how much the incident light illuminates the surface.

Luminous Flux

Is the measure of the light emitted by a source. It’s measured in lumen, and represents the brightness of the light source.



Performance of visual tasks of low contrast or very small size (high detail works, very detailed mechanical works, super detailed pencil drawing)


Performance of visual tasks of medium contrast or small size (intensive reading, handwriting, drawing, sewing, difficult inspection)


Performance of visual tasks of high contrast or large size (casual reading, rough bench and machine works or assembly, easy office work)

CRI (Colour Rendering Index)

Is a quantitative measure of the ability of a light source to reveal the colours of various objects faithfully, in comparison with an ideal or natural light source.

CRI is generally scaled from 0 to 100, with 100 representing the reference light emitted by a blackbody radiator, and with differences in CRI values of less than five points not being significant.

Viewing Angle

This is the full angle at which brightness is half of the brightness from dead center.

A wide angle allows to have a bigger surface illuminated properly, and a more homogeneous distribution of the light from the center of focus to the edges of the working area.


Each light source has its own individual color, or ‘color temperature’.

Color temperature is recorded in Kelvin, and it varies from red to blue with the increase of its value.


Over-illumination is linked to various negative health effects, such headache, fatigue, physiological stress and anxiety.

It’s important to be exposed to enough light to successfully perform a chosen task, but not so much to be blinded by excessive light, to avoid these related health risks.


Under-illumination is responsible for eyes irritation, while making you more tired, sleepy, sluggish and sad.

Without the proper illumination, it’s difficult to keep focus, more effort and concentration are required, but also our mood is impacted on the long run.

Just think of the difference in being yourself in a bright sunny spring day, against the shadow of your former self impacted by a grey, cloudy day, without enough natural sunlight.