Are Measurements for the Cut-Off Gradient of Head Lamps in Different Measurement Distances Possible? 2000-01-0803
In combination with the discussion of a worldwide harmonized passing beam pattern of headlamps in Europe the question has been raised, at which distance between headlamp and photocell the cut-off, or rather the gradient, should be measured.
In principal for the measurement distance there are two positions under consideration:
10 m, because the aiming equipment is designed for a distance of the aiming screen at 10 m.
25 m, because in the relevant ECE-Regulations the required minimum distance for the photometric measurements is 25 m.
The determined gradients are different depending from the distance at which they are measured. This paper discusses the possibility to find a correlation between the measurement procedures carried out at different distances to get assessments of the same cut-off quality independent from the measurement distance.