Interesting BBC summary of research into LED street lamps and the effect they could have on reducing light pollution.
According to the BBC, up to 20 percent of the light from traditional street lamps is scattered “horizontally or vertically because it is difficult to control their beams.”
Replacing those with LED lamps reduces power consumption and reduces the amount light scattered to 10 percent. But researchers have proposed an LED street lamp that would potentially reduce the amount of light scattered to just 2 percent.
Their proposed lamp uses three features to ensure the vast majority of its light is limited to a pre-determined rectangular shape covering the road:
- A special “total internal reflection” lens for each LED designed to focus its light’s rays so that they travel parallel to each other in a single direction. This is rather than criss-crossing and diverging from each other causing many to spill beyond the target area.
- A reflecting cavity into which the lens-covered LEDs are fitted. This helps “recycle” any light rays which fail to travel the desired path.
- A diffuser through which the focused light passes to help tackle unwanted glare.
The researchers suggest that the set-up would also save on electricity costs since it should require between 10 and 50% less power to illuminate a section of road than current LED streetlamps.