Definitions and related interaction and philosophy of glare and visibility, Luminance, Illuminance and other technical terms are presented with discussion of relationships among seeing distance and glare.
The influence of vertical and lateral aiming on glare and visibility is examined in detail, considering various hypotheses on roads and measurement of glare and visibility.
Eight pilots illustrate the interaction of increasing glare and decreasing visibility.
Aiming regulations and practices in different countries like Germany, France, USA and Japan are described in detail. A synthesis on aiming operation result is presented with the five main points to be retained.
Six proposals are made to improve the distinctly sub-optimal situation of lighting today because of generally bad aiming.
Throughout the study, it is demonstrated that even a good headlamp’s performances can be spoiled by bad aiming. A good Xenon low beam aimed 0.5° too low gives seeing performances no better than a typical halogen lamp , while a Xenon low beam aimed 1° high increases discomfort glare from “Just acceptable” to “Unbearable” with the same glare level as high-beam headlamps.
The author closes the 30 page report by presenting 6 proposals to have a better light not only in the labs of car makers but also in the streets.