Analysis of Lightguides Regarding Uniform Appearance and Coupling Efficiency

This paper describes the results of non-sequential ray-tracing simulations about light guides with prisms.

Main problem with prismatic structures is the realization of uniform light output over the whole surface. To get the information about the light distribution and uniformity of innovative light guides without many expensive samples it is necessary to create realistic models for the simulation.

With realistic models the coupling from the reflector into the light guide and the splitting from one light guide arm into two arms was investigated by simulation and measurement.

The effects of the beam splitter on the efficiency and uniformity of the system were of special interest because by using beam splitters the amount of glass fibers and therefore the costs can be decreased.

The best results regarding efficiency and uniformity were reached by using two arms which are converging smoothly together under a very acute angle. By using H6W or H10W bulbs the loss of flux with these beam splitters is acceptable to realize lightguides for position lamps with only one glass fiber per lightguide. But also closed shape light guides are possible with beam splitters.