The nature reserve at RSPB Valley Wetlands is littered with approach lights for the air base next door. There is a clear warning not to look into the lights because they can come on at any moment. They must be bright enough to be seen from a long distance away. I was interested in the design of the outer cover. It is not flat glass but divided into what are probably intended to be like small lenses. There will be a parabolic mirror behind the bulb to pull the light into a beam. Maybe the lenses keep it the beam together more. I have been unable to find out any more about it so I can only speculate.
