Since this thread is lacking Raw info and I get asked this All the time, I figured Id ad this here (could be a FAQ as well
Here is a basic idea of how a Headlamp Projector works. The Main Key is the Lens. A Convex
lens is able to refract/focus light rays very well. Any light rays that hit the "top" part of the lens will be refracted downward and any light passing thru the "bottom" of the lens will be refracted up.
Here is a diagram of how a Convex
lens works. The Arrow'd lines are light rays.
As you can see the light that passes thru the bottom of the lens (that would be refracted upwards) gets stopped by the cut-off
sheild, thus allowing only the downward light rays to pass thru to the road.
Bixenons: These are same structure as Single xenon or (low beam) projectors. The only thing that differs is that there is a solenoid (basic electric motor) attached to the bottom of the cut-off shield allowing it to articulate like a hinge. Once the solenoid gets power from the car, it activates, pulling the shield down to allow ALL the light rays to escape from the reflector thru the projector lens. This is also known as a "FULL BEAM" overseas.
Here is a diagram of the physical structure of Headlight Projector. The Yellow Light Rays are better represented in the diagram above.