Bright beam of light
Laser technology is used in multiple domains stretching from surgical operations to printing. Lasers produce a very narrow and radiant beam of light. Unlike sunlight, laser light waves have similar lengths and travel together with all their wave peaks lined up, in phase. Laser is an acronym which stands for light amplification by stimulated emission of radiation. Albert Einstein first theorized about the stimulation of light emission in 1917. He used Planck’s law of radiation to describe probability coefficients for stimulated emission of electro-magnetic radiation. His theory proposed that electrons could be stimulated into emitting light of a particular wavelength. This would become the founding principle of all lasers used today even if it took another 40 years or so before scientists were able to come up with a functional device.
While laser technology has enabled huge technical breakthroughs in a wide variety of areas, a number of safety concerns are specific to laser light. Lasers can cause eye injuries to anyone who looks directly into the beam or its reflections from mirror-like surfaces. Moreover, the diffuse reflections from a high power beam can equally cause eye damage. High power lasers can also cause skin damage and ignite flammable materials.
The type of damage and the threshold at which each type of lesion is produced depend on different factors such as exposure time and the absorption properties of the material exposed to laser light.
IEC global classification of laser products
IEC Technical Committee 76: Optical radiation safety and laser equipment, was set up to produce safety standards for lasers as well as LEDs. One of the TC’s major endeavours is the publication of IEC 60825-1. This standard offers a global classification scheme of laser products according to their safety requirements and emission limits. It is widely used by industry and is viewed as the reference for laser equipment by manufacturers, installers and regulators in most countries around the world. For instance, the standard specifies the determination of the nominal ocular hazard distance from the laser source. “If you are outside the hazard distance you are safe from accidental exposure. If you are too close and look into the laser beam, there is a real risk of eye injury,” explains Jan Daem, an expert inside IEC TC 76. He is also environmental compliance officer at Barco, one of the leading manufacturers of image projectors used in cinemas. The company notably manufactures laser projectors, which are much more energy efficient than traditional light projectors and are also expected to project a better image on the screen.
IEC 60825-1 is a horizontal publication, meaning that it is generic and provides a global framework for most other IEC TCs which produce standards for specific laser products, such as printers, hair removal devices, barcode scanners, and so on. It ensures that all the standardization documents produced by each TC are coherent.
TC 76 is divided into seven working groups (WGs) which have different scopes. WG 7, for instance, produces standards for high power lasers. Jan Daem is a member of three of these WGs. The TC has published 35 documents and is working on 12 publications, all new editions of existing standards. It works closely with the International Commission on Non-ionizing Radiation Protection (ICNIRP) and the International Commission on Illumination (CIE).
One of the important standards Daem worked on is IEC 62471-5, which applies to image projectors. “We took three years to publish this document, starting from scratch. We got people from industry to work together and we started first by evaluating scientific data. Following that, we proposed a pragmatic way of measuring conditions for image projectors based on the end user’s exposure,” he explains.
Boon for industry
Being involved in standardization work brings huge benefits for his company as well, according to Daem. “It is a great help: we have the heads up about any changes in standardization, which means we don’t need to redesign any of our products for them to be compliant. The communication with our in house validation and design team is much easier. The whole design process is better streamlined all the way to market launch.”
Daem is also keen to emphasize the welcoming working atmosphere inside IEC TC 76. “Many of the members are total experts who have been working in the field for 30 years. They were all incredibly helpful when I joined and I learnt a lot working with them. There was a great amount of guidance. The TC is very open to scientific and technology advances, as well as accepting and integrating these changes into the standards.”
The time consumed working in standardization not only serves a purpose for the community at large – it also helps the manufacturers involved to be better prepared to meet market requirements.