What is optical radiation?

Ultraviolet (UV) radiation is the highest-energy form of optical radiation and includes the wavelengths from 100 to 400 nanometres (nm).

The term "visible light" refers to the region of the electromagnetic spectrum that humans can see. These wavelengths range from 400 to 780 nm. Some animals can see a wider region of the spectrum than humans.

Infrared (IR) radiation is also referred to as thermal radiation. It is next to visible light as the spectrum moves towards longer wavelengths – from 780 nm to 1 mm.

Optical radiation – natural or artificial

The natural source of optical radiation is the sun. Optical radiation can also be generated artificially, e.g. in lasers, lamps, radiant heaters, sunbeds, electric arcs, etc. Some sources of optical radiation, such as the sun, emit every region of optical radiation (UV, VIS and IR). By contrast, artificial optical radiation sources can also produce just narrow regions of optical radiation (e.g. LED, lasers). In some sources of optical radiation , parts of the optical spectrum are filtered out.

Excessive exposure can be harmful

People who expose themselves to excess optical radiation can damage their skin and eyes. This applies both to optical radiation of a natural origin and to artificially generated optical radiation. The type and extent of damage depend primarily on the wavelengths of the radiation, the duration of exposure, and the irradiance. Even radiation in the visible region can be detrimental to health. Staring at the sun damages the eyes not only because of the UV radiation but also, above all, because of the high intensity of the visible light and infrared radiation.

UV radiation – acute and long-term damage

UV radiation can cause not only immediate (acute) but also long-term (chronic) damage. For example, acute damage due to UV radiation includes sunburn of the skin or "welder's flash" in the cornea of the eye. Chronic damage due to UV radiation is premature ageing of the skin, skin cancer and - in the eyes - opacity of the lens (cataract).

IR radiation can be detrimental to health

Excessive exposure to IR radiation can also be detrimental to health. Some studies have shown that chronic exposure to IR radiation alone or in combination with UV radiation can cause damage to the skin.

Too much light can also be harmful

If the irradiance exceeds certain levels, visible light can also be harmful – especially to the eyes. This is particularly true of the high-energy blue region of the visible spectrum ("blue light hazard"). Lasting damage to the retina can be caused by looking at the sun or powerful sources of artificial light, e.g. lasers, without eye protection.