A Recommendation for the U.S. Lower-Beam Pattern for Visual/Optically Aimable Headlamp

Headlamp aiming is one of the most important factors of lighting performance. In the U.S, visual/optically aimable headlamps must have a certain cut off vertical gradient for adjustment, and should conform to photometric requirements at its position. The manufacturer can choose a vertical cut off position either on the left side (VOL) or the right side (VOR) of the optical axis for particular headlamp system designs.

However regulations aren't clearly written on headlamp aiming position on the vehicle. Even if the headlamp aiming is positioned correctly on the vehicle, the beam may cause discomforting glare to oncoming or ongoing road users, depending on the height of the lamp on the vehicle. This could also cause safety problems.

The discomforting glare to oncoming drivers and the mirrors of ongoing traffic is compared between VOL and VOR of each headlamp height. This paper recommends optimum Lower-beam patterns at each headlamp height.