Optical radiation is part of the electromagnetic spectrum. It is subdivided into ultraviolet radiation (UV), the spectrum of light visible for man (VIS) and infrared radiation (IR). Optical radiation ranges between wavelengths of 100nm-1mm.
The greatest risk to health from non-laser optical radiation is posed by UV radiation from the sun. Exposure of the eyes to UV radiation can damage the cornea and produce pain and symptoms similar to that of sand in the eye. The effects on the skin range from redness, burning and accelerated ageing through to various types of skin cancer.
The second greatest risk to health from optical radiation is posed by the misuse of powerful lasers. High-power lasers can cause serious damage to the eye (including blindness) as well as producing skin burns.
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A laser device can emit both visible light and invisible ultraviolet and infrared radiation.
Are lasers dangerous?
Whether or not a laser is dangerous depends upon its use and output power. Very low power lasers are safe. Moderate to high power lasers can be hazardous to the eyes and, in some cases, the skin.
Countries such as the USA, where many diode laser pointers come from, have laser safety standards with mandatory classification and labeling requirements. In this system, all lasers are classified into one of four classes. The classification number (one to four) and appropriate warning statements must be labeled on the device.
However, some companies sell lasers on-line along with:
- safety warnings
- availability to purchase protective eyewear
- age verification (on-line)
- requirement for reading hazard warnings (on-line)
- availability of a free (on-line) safety course
There seems to be no restriction on who can purchase a laser, and no restriction on the classification of laser that can be purchased!
Class 1 lasers do not generally present a hazard. Nevertheless, avoid pointing lasers to the eye.
Emit in the visible portion of the spectrum (400 to 700 nanometers. This type of laser does not present a health hazard provided one does not focus the beam directly into one's eyes. Furthermore, eye protection is generally achieved by the aversion response. Class 2 lasers have powers less than1 milliwatt (mW).
Class 2M lasers
Emit in the visible portion of the spectrum (400 to 700 nanometers). Eye protection is normally afforded by the aversion response for unaided viewing. However, Class 2M is potentially hazardous if viewed with certain optical aids (magnifying instruments).
Class 3 lasers may be hazardous under direct and specular reflection viewing conditions, but are normally not a diffuse reflection or fire hazard. These lasers fall into one of two sub-classes: 3a and 3b.
Class 3a Lasers
They are slightly more powerful than class 2 lasers and one should not focus the laser beam in anyone's eyes. Class 3a lasers, when viewed through a magnifying lens, have the ability to cause harm. Class 3a lasers are not fire hazard or diffuse-reflection hazard
These lasers are dangerous and can damage to one's eyes instantaneously upon direct exposure. They require a longer exposure time to burn skin. However, they are not a diffuse reflection or fire hazard. Class 3b lasers can have powers up to 500 mW.
Class 4 lasers are dangerous and can damage eyes and skin instantaneously upon exposure. Some can damage eyes even from a diffuse reflection. Class 4 lasers can cause materials to ignite. Class 4 lasers have powers higher than 500 mW.
Sun & ultraviolet rays
Ultraviolet solar radiation (Outdoor UV
), ultraviolet sun lamp radiation, and ultraviolet sun bed radiation (Indoor UV
) are known to be human carcinogens. On sunny days, people should protect their skin with sunscreens, shade, hats, clothing and sunglasses. Babies SHOULD NOT be exposed to the sun.
Visible light -non-laser optical radiation
Visible light ranges between wavelengths of 380-780 nm.
Environmental Health Services, Radiation Protection, developed a Radiation Issue Note (RIN 27) addressing the exposure of the general public to visible light emitted by large outdoor LED screens.