The solar radiation

The solar spectrum is made up of three families of wavelengths:

Ultraviolet rays or UV from 100 to 380 nanometers

Are not perceptible by the eye. They are nevertheless most harmful and are divided into 3 types:

• UVA (315 à 380 nm) are the principal cause of the ageing of the eye
• UVB (280 à 315 nm), harmful, are at the origin of the sunburns.
• UVC (100 à 280 nm), most dangerous for the eye. They are fortunately filtered by the layer of ozone.

UV400 appelation guarantees a 100 % protection against these radiations.  Nevertheless, the proportion of UV increases according to the intensity of the solar radiation.  Altitude, the light and its reflexion play a role in determining the choice of a lens.

The visible light from 380 to 780 nanometers

It corresponds to the various visible colors that the eye can see. Breaks up as follows:

• 380-500 nm : purple-blue
• 500-600 nm : vert-jaune
• 600-780 nm : orange-rouge

Infra-reds of 780 Nm with 2000 nanometers

imperceptible, they are responsible for a phenomenon of heating and drying. Although not very dangerous, they can be at the origin of certain lesions of the eye, following a too intense exposure.  Beyond are the radar waves.