Nothing beats photons. We can align these quantum particles into columns of light to make lasers, which have turned out to be pretty handy. Although lasers are useful in every corner of the world, they can be hazardous if used improperly.
That's because lasers have a peculiar property called radiance, which means that they are brighter than any known light source. The properties that can project lasers to the Moon make them strong enough to be hazardous even over those distances. With radiation or with other light sources exposure hazards decrease rapidly with distance; not so with lasers.
Members of IEC technical committee 'Optical radiation safety and laser equipment' IEC TC 76 address laser safety by writing a multitude of safety Standards. IEC TC 76 is so large that its meetings typically involve 65 delegates from 10 countries for each meeting. Safety of laser products – Part 1: Equipment classification and requirements IEC 60825-1, the basic Standard of IEC TC 76 is an IEC, top-10, best-seller. The Standard applies to the safety of laser products emitting laser radiation from the ultraviolet to the infrared within the 180 nm to 1 mm wavelength range.
Jerome Dennis, now on his third term as IEC TC 76 Chair, wants people to understand that laser products, though hazardous, can be used safely if the proper steps are taken and users are properly trained. Dennis has worked to develop laser safety Standards for 25 years, most recently as the lead technical person in maintaining the United States Food and Drug Administration's Center for Devices and Radiological Health.
To keep abreast of the latest in laser biological effects, IEC TC 76 relies on photobiophysical journals, as well as the International Commission on Non-Ionizing Radiation Protection which provides exposure limits that IEC TC 76 translates into safety Standard emission limits and product requirements.
The Standards address user safety of more hazardous lasers by providing requirements for controls, indicators, and warnings in instructions provided by the manufacturer. The instructions, for example, warn against ancillary hazards about which the laser product manufacturer is aware.
'Although our primary responsibility is to product manufacturers, we also recognise there's other information the users need in order to use laser products safely,' says Dennis.
Red light for green lasers
Lasers are divided into four hazard classes, ranging from not hazardous to quite dangerous. Dennis says that IEC TC 76 aims to recognise the hazard levels and to specify requirements to control the hazards without being overly restrictive.
For example, for the garden-variety, red laser pointers, the risk of injury risk is small. Higher luminous-power, and held green lasers are of much more concern because they are more powerful. There have been incidents of individuals directing these green lasers at aircraft. 'Imagine somebody performing a vision-critical task such as trying to land an aircraft and all of a sudden the cockpit lights up with green light,' says Dennis. Many European countries and Japan have prohibited the sale of laser pointers greater than class 2. The US Customs and Border Protection can block the import of laser products that fail to conform to the US/FDA/CDRH Standard that is very similar to the IEC 60825-1.
William Ertle, President of Rockwell Laser Industries and IEC TC 76 Secretary explains that different wavelengths affect different areas of the eye. Long wavelength infrared lasers such as CO2 can cause severe skin burns. Laser equipment may also give rise to other hazards such as fire and electric shock. Lasers used in industrial applications generate thousands of watts and can start fires. Ertle stresses that in these instances lasers pose ancillary hazards; the primary beam is not bringing harm. And, the dangers come from users not properly trained. Joint efforts of IEC TC 76 and ISO (International Organization for Standardization) TCs have addressed laser guards.
A bright future
IEC TC 76 boasts members who work for manufacturers, testing labs, and for government safety organisations, such as the FDA. 'We're blessed with a committee of very bright people who respect each other very much and keep each other informed,' says Dennis, 'I'm proud to be associated with them.'
Dennis is also keen on liaising with other committees interested in laser applications. He'll have this chance in October 2010 when IEC TC 76 meets during the general meeting. IEC TC 76 primarily develops horizontal Standards, which means they apply to all lasers no matter the use, industrial welding, drilling, medical settings, laser light shows, laser printers, and so on. Many other committees develop Standards for particular types of products that may contain lasers. Meeting with such committees will help foster understanding.
'We're just overjoyed that we've been invited to the general meeting this year because it gives our technical experts an opportunity to meet with experts from other committees including fibreoptic communications, and medical equipment and consumer products,' says Dennis.
In the meantime IEC TC 76 has just re-approved its Standard for fiberoptic communications and is simplifying labelling to accommodate multilingual users. 'We hope that Standards remove some of the mystery surrounding lasers and recognise that these products are under the control of Standards,' says Dennis. 'Where there's a hazard, it's not hidden.'
'It's not all Buck Rogers.'
By Jeanne Erdmann and reprinted with permission from IEC e-tech April 2010.
- IEC 60825-1 Safety of laser products – Part 1: Equipment classification and requirements
- IEC 60825-2 Safety of laser products – Part 2: Safety of optical fibre communication systems
- IEC 60825-4 Safety of laser products – Part 4: Laser guards
- IEC 60825-12 Safety of laser products – Part 12: Safety of free space optical communication systems used for transmission of information
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