How is the cutoff line created?
First, the reflector shapes a rough cutoff above the shield. Then, the cutoff shield defines the final shape of a horizontal line on the wall separating darkness and light. Because a razor sharp beam cutoff is needed, the reflector beam is overlapping the cutoff shield edge, so that maximum intensity is kept close to cutoff line. The light that hits the gray cutoff shield will partially be converted to heat and partially deflected into stray light.
