Main Beam

Function

The main beam is meant to homogeneously illuminate the road in front of the car. Driving on main beam is only allowed when there is no oncoming traffic which might be dazzled. In contrast to dipped beam there is no limited light/dark boundary. Due to the density of the traffic in Western Europe, main beam might not be frequently used, in Northern Scandinavia, which has much less traffic, this is different.

How it works

As the figure above shows main beam always uses the whole paraboloid reflector. Theoretically, a paraboloid is the result of rotating a parable around its main axis. It has in contrast to ellipsoid reflectors only one focussing point. Beams leading off from this point leave the headlight parallelly bundled, making the paraboloid reflectors well suited for main beam. The second (left) coil inside the halogen bulb is placed exactly in the focussing point. Without any cover the beams are reflected. Main beam might be used in a four-headlight system too. Other systems such as lamps with ellipsoidal reflectors can only function in a four-headlight system.