A free-form side-emitting lens for airfield lighting

Side-emitting lenses are essential devices in some special lighting fields. Two types of side-emitting lenses with refractive and total reflective free-form surfaces are introduced. The principles of geometric optics and non-imaging optics are adopted to construct the free-form surfaces without complex mapping or a differential iteration process. As an example, an elevated taxiway edge light is designed for airfield lighting. A side-emitting lens with two sawtooth additions on top is designed to meet the luminous intensity distribution required by the US Federal Aviation Administration (FAA). An analysis is carried out to determine tolerance limits during manufacture and installation. Computer simulation results show that a side-emitting efficiency of 85.4% is achieved for a Cree XP-E LED. The light distribution of this elevated taxiway edge light complies with the FAA regulations.