DJs beware - Buying a laser could be a waste of your money!A large number of lightshow lasers are now available on the market, mostly aimed at the DJ market. Prices have tumbled over the last few years, and these lights have become increasingly popular. However, a laser is not 'just another lighting effect' - unlike other forms of lighting, the light energy does not disperse much over distance, and even a small laser can cause permanent eye damage. As an example, a small 5mW handheld red laser pointer is approximately the same brightness as the sun! Furthermore, the eye is around 30 times more sensitive to green light than red, so a typical class 3b 100mW green laser, as fitted to a typical small laser projector, is 600 times brighter than the sun! Unfortunately, because of the way the eye corrects itself, laser eye damage can go unnoticed but is cumulative and usually permanent. Although the sale of handheld laser pointers >1mW is now banned on Ebay, projectors containing much more powerful lasers are still readily obtainable.
European regulatory authorities have finally woken up to this risk, so in April 2010, new legislation - CD227 - Control of Artificial Optical Radiation at Work Regulations - comes into force.
The effect of this legislation will be that anyone operating a Class 3B or Class 4 laser in public, where there is any risk of anyone being exposed to the beam, will have to prove that it's safe - this will mean having a full safety analysis, including Maximum Permissable Exposure calculations, and the laser will need to be fitted with a scanner failure detection board to prevent static beams reaching the audience.
If your laser does not comply, the only way you will be able to use it legally will be to point it at the ceiling; any laser that points at the audience must comply with the new regulations. The vast majority of laser projectors sold in the last few years do not comply.
A good source of information about lasers is the Photonlexicon forum (ask Google!) - this also contains some very useful reviews of a number of sellers - buyer beware!