Group sets safety threshold for blue LED

17 Jun 2002

Prolonged exposure to incoherent blue light at 460 nm is damaging tothe human retina, says a US Japan research collaboration. Theresearchers say that they are the first to put down a safety level of 11mW/cm2 for light from an LED.

Donald Armstrong, from Florida's College of Veterinary Medicine, toldILSC 99 that the figure is extrapolated from the effects of the light onthe retinas of rhesus monkeys. The tests projected 3 mm spots of lightat 11 mW/cm2 on the retinas of anaesthetised animals for periods from12.5 to 90 minutes.

Approximately 30 minutes exposure was enough to produce long-lastingdamage. The researchers now want to investigate the safety thresholdsfor red and green LEDS and blue lasers.