Optical design of precision approach path indicators in a portable runway lighting system

Portable runway lighting systems pose an interesting illumination challenge. They are typically used in harsh environments where generators or batteries are used to provide electricity. As a result, not only do the systems have to satisfy the regulatory requirements which determine the light intensity profile but they also need to be highly efficient and within a compact design. This paper summarises the optical design and performance of a PAPI system using LEDs which are coupled into a waveguide to generate the required light distribution at an intermediate plane after the waveguide. The use of waveguides means that a single projection lens is used to generate the final beam and this images the output of the waveguides into the far field.