In the design of the headlight systems, the conflicting targets – visibility range and safety have to be considered. In order to achieve a large visibility range, long-range headlights having a high luminous intensity and a sufficient dispersion on the side and elevation are used; the optical demands being rather small. Further, the low beam must be so designed as to avoid dazzling the driver of the oncoming vehicle. The legislation prescribes a minimum and maximum lighting power, depending on the illuminated zone in front of the vehicle.