Changes in Angular and Spatial Distribution Introduced into Fiber Optic Headlamp Systems by the Fiber Optic Cables

Design of fiber optic headlamp systems incorporates coupling between a source and the beam-forming optics. In many situations, the coupling includes a bent section of fiber to minimize the package size of the headlamp system. The bend can introduce changes in the light distribution which impact the headlamp performance. The bent fiber is investigated using state of the art illumination design software. The intensity (angular) distribution, the illuminance (spatial) distribution, and the total flux at the output of the bent fiber are the main performance parameters investigated. In addition, modeling results showing that the illuminance distribution varies as a function of view angle are included. A model that incorporates an attenuation coefficient into the fiber clad is shown to provide excellent agreement with measurements. In addition, a novel method for minimizing the changes in the fiber output with a tight bend is shown.