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Light

"Light" refers to the visible region of the optical radiation - between UV radiation and infrared radiation. Most people can perceive wavelengths of between about 400 nanometres (nm) and 780 nm visually.

Light from artificial radiation sources has been used for medical and cosmetic purposes since quite a long time (e.g. for blue light therapy for the treatment or prevention of neonatal jaundice (icterus neonatorum), for epilation and tattoo removal). Many lasers and intense pulsed light sources (IPL, flash lamps) use various wavelengths of light.

What does visible light mean?

Light or "visible light" refers to the visible region of the electromagnetic spectrum – that is, the range of wavelengths that trigger brightness and colour perception in humans. It lies between UV and infrared radiation. Most people can perceive wavelengths of between about 400 nanometres (nm) and 780 nm visually.

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Protection against visible light

The eyes are of paramount importance in any consideration of the potential risks due to visible light, especially with regard to photochemical effects on the retina. Although thermal damage – that is, damage due to heating – is possible, this only occurs at higher irradiances.

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Querschnitt durch das menschliche Auge, die Pfeile kennzeichnen die Durchlässigkeit für optische Strahlung

Effects of light

Light allows us to perceive our surroundings using our eyes. Light is not only used for sight but also has an influence on endogenous messenger substances and sets the "body clock". If the irradiance exceeds certain levels, light can also be harmful – especially to the eyes.

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