No abstract

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.

To eliminate axial misalignment-induced measurement errors of discrete light-emitting diode arrays in the far-field condition, a robust and effective method for correcting the measured luminous intensity distribution is proposed. The precision of the correction can be determined beforehand by setting a criterion which can also be used to determine the required test distance. To validate the feasibility and practicability of the proposed approach, numerical simulations of light-emitting diode arrays with three kinds of typical luminous intensity distributions were performed. In addition, the test distances as a function of the light-emitting diode luminous intensity distribution, packing density and dimensions under translational misalignment were analysed. Some beneficial operating methods and rules for practical application are summarised. Finally, physical measurements of several experimental examples were collected. The correction results agreed with the desired data and again proved the utility of the presented method.