10. Feb 2015

Observations from Karl Albert Fischer

Rapid development
The congress documented the status quo of LED technology worldwide and once again showed the rapid tempo at which developments are taking place in this sector. The exhibitors presented products with surprisingly new light quality – highly welcome when you think that these light sources are soon to become the primary basis for the vast majority of lighting solutions. Colour quality Emphasis was placed not only on the brightness or light output of LED light sources, but their continually improving colour quality. As long as an LED spectrum still contains significant peaks and, above all, relatively high blue content, there will always be photobiology experts who will refrain from recommending LEDs – because the spectrum is too far removed from the homogeneous spectrum of the light emanated by thermal radiators (such as tungsten halogen lamps or sunlight). Some months ago we were made aware of an LED spectrum that beats everything we have seen so far on the market when it comes to the spectral quality of LEDs: a spectral curve whose uniformity is very close to that of daylight, which only features one small blue peak (and is thus hardly likely to present a “blue light hazard” to the eye) and still achieves a colour rendering index of over 90 per cent (CRI = 92).

It is unfortunate but true that the spectral composition of such new artificial sources is not visible to the naked eye – be the viewer a lighting expert or a layman with no notion of what spectrum means. The luminosity curve can only by revealed with any accuracy when using a spectrometer. Even when the light emanated by a lamp is perceived by the viewer as being warm light, the light spectrum may still contain a number of blue peaks and thus, according to experts from the field of photobiology, present a danger to the eye.

The main topics of discussion
lighting solutions that address our biorhythms and support human health and well-being because they replicate or align with natural lighting conditions over the course of the day – referred to by the lighting industry as “Human Centric Lighting”

-changes in colour temperature and brightness – technologies and tools: the combination of warm white and cool white LEDs enable colour temperature and brightness to be adapted and programmed to meet individual needs

-lighting spaces using RGB fixtures together with tunable white LEDs. Fascinating coloured lighting installations and spatial atmospheres can be designed – not only using RGB technology. Developers from the lighting industry exchanged ideas on these topics with representatives from the fields of science and research, with some discussions developing into heated debates. But how do we stand when it comes to communicating with lighting design practitioners? A short exchange I had is worth a mention in this context. I took part in a discussion workshop comprising professionals from different specialist fields and happened to ask: “So where are the lighting designers?”, to which a woman in my group replied: “I think you are at the wrong congress?”

Dynamic light
What also stood out in Bregenz was that many of the companies present are making a tremendous effort to deliver truly high-quality light, especially with the goal of enabling dynamic lighting schemes that replicate daylight conditions over the day. Their approach has nothing to do with the comparatively primitive RGB technology many have been using up to now, but already comprises up to ten individual colour LEDs whose light is added to a light spectrum which is substantially more complete – all of which can, of course, be controlled and modulated to suit a time schedule. Equally advanced are the lenses and optical technologies available today – both glass and plastic. Reflectors have also undergone some improvements. Photometry – measuring light – is still very relevant to our work today. I saw at least five Ulbricht spheres of different sizes at the congress. And there were sophisticated robot systems on display that enable a luminaire to be measured from different sides and angles. Light quality today is no longer purely a question of technology, but rather of the will to actually apply new findings. The next LED professional Symposium will be taking place from 22. to 24. September, 2015 in Bregenz/A.

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