The Need For Laser Safety laseroptical.co.uk

The purpose of laser safety is to minimise the risk of laser accidents, particularly eye injuries. It is possible to cause permanent eye injuries with very small amounts of laser light.
The predominant cause of laser radiation injuries are from the thermal effects of laser light. Eye injuries can be caused moderately powered lasers. High powered lasers can burn the skin. Very powerful laser cause diffuse reflection from a surface and this too can be hazardous to the eye.

The coherence and low divergence angle of laser light, aided by focusing from the lens of an eye, can cause laser radiation to be concentrated into an extremely small spot on the retina. A transient increase of only 10 °C can destroy retinal photoreceptor cells. If the laser is sufficiently powerful, permanent damage can occur within a fraction of a second, which is faster than the blink of an eye. Sufficiently powerful lasers in the visible to near infrared range (400-1400 nm) will penetrate the eyeball and may cause heating of the retina, whereas exposure to laser radiation with wavelengths less than 400 nm or greater than 1400 nm are largely absorbed by the cornea and lens, leading to the development of cataracts or burn injuries.