title: Reliability of point source approximations in compact LED lens designs.
abstract: In many applications, compact concentrator lenses are used for collimating light from LEDs into high output beams. When optimizing lens designs, the LED is often approximated as a point source. At small lens-to-LED size ratios this is known to be inaccurate, but the performance compared to optimizations with more realistic models is rarely addressed. This paper examines the reliability of a point source model in compact lens design by comparing with optimisations that use a factory measured LED ray-file. The point source is shown to cause significant, unnecessary efficiency loss even at large lens sizes, while the use of a ray-file allows for a >55% reduction in the footprint area of the lens. The use of point source approximations in compact lens designs is therefore generally discouraged.
authors: Dept. of Physics and Nanotechnology, Aalborg University, Skjernvej 4A, DK-9220 Aalborg, Denmark. tkj@nano.aau.dk
authors: Thøger
authors: T
authors: Kari
authors: Jesper
authors: J
authors: Gadegaard
authors: Thomas
authors: T
authors: Søndergaard
authors: Thomas Garm
authors: TG
authors: Pedersen
authors: Kjeld
authors: K
authors: Pedersen