Lux and light field
Busch & Müller states the light output of headlights using the unit Lux. A Lux value provides
the illumination level in relation to its distance
from the light source – it is exactly this relation
which is a deciding factor when considering a
headlight, because it states the amount of light
on the road. The value Lumen states how much
light exits the headlight at the light source and
it cannot be told whether that light shines onto
the road or is lost as stray light. However, even
Lux is an incomplete value when talking about
the output of a headlight.
Also important is the quality of the light field
which is created on the road. Its width, depth,
homogeneity as well as its glare free light/dark
boundary directly ]affect how it is perceived by
the observing eye. All those qualities cannot be
stated using measured data. This means: Only
when one looks at the light fi eld as a whole, the
true quality of a headlight can be appraised.
From page 6 of
the catalogue.