LED’s and photo-biological safety

Perth, 27th May 2010

It is well known that lasers are a safety hazard when it comes to the human eye. Direct exposure to a laser beam can cause immediate and irreparable damage to the retina. Hence lasers have always been classified as hazardous light source. There are strict standards for the safe use of lasers. But there are also reports on the photo biological safety of other lamps and systems.

So not surprisingly one of the debates going on is about the photo biological safety of LED’s. While some years ago this may have been a non issue because of the low intensity of LED’s, the fast development in performance has created LED systems with very narrow beams and very high intensities. Some of the LED systems currently available have such a high brightness …

One of the issues that makes the assessment of LED safety difficult seems to be the measurement of its radiance, the quantity of light that may cause retinal damage. This is due to the small size and directional characteristics of LED’s.  Further issues that influence the results are exposure time (also known as MPE or maximum permissible exposure) and distance away from which the radiation is observed. The CIE is one of the organizations in the process of analyzing and producing guidelines for the safe use of LED’s.

While pretty much an untraded terrain in terms of lighting design (at least to my knowledge) it is easy to see that regulations and due care will need to be applied now and in the future when applying high intensity LED systems. Contrary to high intensity gas discharge floodlights which are obvious and generally safely mounted away, LED systems are small and compact, often used in a small building envelope and because of their high directional character sometimes surprisingly bright and glaring when confronted head on. Let’s keep “an eye” on this issue…

27. May 2010 by Martin Klaasen
Categories: light and health | 3 comments

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