A comparative survey of some possible systems of polarized headlights.

In a polarizing headlight system polarizers are placed on automobile headlights and in a viewer before the eyes of automobile drivers. These polarizers are so oriented that the viewer is crossed with the headlights of an approaching car. This blocks most of the light from approaching headlights. A polarizing system has other features which make it different from a non-polarizing system. The amount of the polarized component of the reflected light from an object illuminated by a car’s headlights which is transmitted back through the viewer in the same car depends on the type and orientation of the polarizers. Thus objects have different brightness depending on the polarizing system being used. Similarly, the contrast between objects and their background will be different for different polarizing systems. In this paper some basic matrices of an optical calculus are derived. This calculus is then used to show the orientation of the headlights and viewer polarizers for all possible polarizing systems. For each of these systems the relative brightness of a specularly reflecting object is determined. Finally, equations are derived for the contrast of various types of objects with their background and a few special cases are calculated.