The LED revolution dealt a fatal blow to fibre optic lighting, right? Why would anyone want to use that kind of clunky kit when there’s an elegant, light-on-its-feet, technology like LED available. Well, whatever our techie friends might think, the fibre optic lighting system is far from dead. Indeed, its demise has been greatly exaggerated as fibre optic technology has found a way to live in an LED world.
For our younger readers, this is what I’m talking about:
There are always places where it’s not so easy - or safe - to run electrical wiring due to a lack of space. For those occasions, optical fibre is perfect.
A fibre optic system consists of three elements: the light engine at one end, the light delivery system at the other end and a length of optical fibre connecting the two.
The light engine
The light engine is a special projector housing, designed to deliver a focused beam of light into the end of a bundle of fibres, which is known as the harness. The efficiency of the system depends not only on the luminous efficacy of the light source, but also on how much light can be delivered into the harness.
One of the traditional limiting factors of fibre optic lighting was how to control the heat within the light beam from a halogen or halide lamp; as heat tends to damage the harness.
When it came to heat control, LED proved itself to be very helpful. The different thermal arrangement of LED, with heat being generated at the back of the module rather than in the light beam itself leads to a far better rate of transmission into the fibre harness.
An ideal optical fibre would provide 100 percent total internal reflection along its length, with no shift in the colour spectrum and minimal losses in light intensity. This, however, is a very tall order.
Early fibre optic systems suffered due to inefficiencies within the fibres themselves. Light was lost due to impurities in the material, the light tended to leak and the longer the fibre length, the more likely it was that there would be colour inconsistency.
Modern fibres have a high refractive index so that the photons in the light beam bounce along the inner walls of the fibre core until they exit via the light delivery system. The fibre cables that are bundled into the harness come in a variety of diameters, so light outputs can be varied according to what you want the light to do.
The light delivery
While the real technology is tucked away above ceilings and inside cabinets, the light delivery is the thing that everyone cares about. Typically, there are three ways that fibre optic light is delivered into a space.
Simply polish the end of an optical fibre and you get an effective glow of light, ideal for decorative features like star ceilings, chandeliers and integration into display features.
Downlights and way-marker lights represent a very popular use of fibre optic lighting, often in locations where electrical wiring isn’t acceptable.
Fibre optic lighting made its name in creative museum and gallery display projects and that is still very much the case. Small-scale fixtures with close control on light output and all electrical wiring tucked away in the bottom of a cabinet is still one of the the most popular uses of the technology.
Let’s finish with a recap of why fibre optic lighting is still so popular:
- Fibre optic lighting can be installed into secure enclosures. No maintenance is needed at the point of delivery and the light engine can be located outside of the secure zone.
- Fibre optic systems can use one light source for a large number of lighting points. A star ceiling can consist of over a hundred ‘stars’, but maintenance is only required at one location. With LEDs, the length of time between light source changes is even greater.
- There is no UV radiation from a fibre optic system and there is no heat within the light beam, which makes it an ideal contender for the display of delicate materials.
- You'll be able to find out more about fibre optic lighting at the LuxLive 2016 exhibition in London on Wednesday 23 November and Thursday 24 November. Entry is free is you pre-register here.