SPONSORED: LASER SAFETY Shining a light
on safety Keely Portway gets the low-down on some of the emerging risks when it comes to lasers, and gains some advice on how users can keep themselves safe
T
he first laser came into being back in 1960, when American engineer and
physicist Theodore H. Maiman, who was working at Hughes Research Laboratories – part of Hughes Aircraft Company – successfully fired up a prototype, based on theoretical work by fellow physicists, Charles Hard Townes and Arthur Leonard Schawlow. Some six decades later,
it’s no secret that lasers have dramatically increased in popularity across research, sciences, medicine and aesthetic treatments, as well as industrial applications. What has been slightly surprising, however, has been the move into the small business and consumer sphere. Recent years have seen an influx of hobbyists flocking to popular consumer websites and resale sites to order laser marking or etching equipment and PPE supplies from popular consumer websites, in order to make personalised products that they can sell. Preetesh Mistry, sales
manager for photonics at Pro-Lite Technology, explains why this is a concern: “People who have worked with lasers throughout university or during research and development or product development work in industry will be clued up to the dangers that they can present. But if consumers, who arguably have less knowledge surrounding lasers, order equipment from these sites, they don’t know where it’s coming from. This is concerning, partly because
28 Electro Optics November 2022
different countries have different standards, but also because the documentation may not always have the right information for people within Europe in terms of specifications and safety requirements for them to work out what is legally safe. More worryingly, these users may not understand the potential dangers and how to avoid them.”
Recognising hazards Such dangers include the potential beam related hazards that can affect the eyes and the skin. The lasers can cause biological damage both, through temperature effects from absorbed energy and also through photochemical reactions, depending on the wavelength of the light and on the tissue being exposed. For example, when it comes
to the eyes, near-ultraviolet wavelengths result in much of the radiation being absorbed in
the lens. This means that the effects are delayed and may not occur for some time, in the form of cataracts. With far-ultraviolet (UVB) and far-infrared wavelengths, however, the bulk of the radiation is absorbed in the cornea, which can cause Keratoconjunctivitis if too-high doses are received. Visible and near infrared wavelengths cause most of the radiation to be transmitted to the retina, and there is a risk of flash blindness or even retinal burns. When it comes to the skin,
thermal damage can occur if tissue is heated to the point where proteins become denatured. Photochemical damage is also a risk as light starts a chemical reaction in tissue – this is prevalent with short-wavelength light. Laser pulses shorter than about 1µs, meanwhile, can cause a rapid rise in temperature, resulting in explosive boiling of water. Depending on the wavelength,
the beam can penetrate both the epidermis and the dermis. Far and mid-UV can be absorbed by the epidermis, which can cause a sunburn effect. UV exposure is also associated with an increased risk of developing skin cancer and premature ageing.
Regulations and standards A key development in preventing the above has placed the onerous firmly on the supplier when it comes to PPE equipment. Mistry explains: “There was an update to the original PPE directive a little while ago, which meant that it was superseded by EU regulation 2016/425. One of the key points is that the responsibility for selecting the correct eyewear and other protective equipment is now on the suppliers. In the past, someone could call a supplier and ask for a quote for a particular filter and they
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