How Projector head lights work?

Visibility is an important tool while driving. Not being able to see an object, or people, in the road can lead to very dangerous situations. This was the understanding behind the concept of the headlight in the first place. Headlights are lamps that illuminate the road ahead. headlights improve night visibility while enhancing the appearance of the vehicle.

The first main projector headlight made its debut in 1981 on the Audi Quartz. The car was designed by Pininfarina for the first Audi Quattro-based concept car. During this time, the concept of a projector headlight was also being developed by Hella in Germany and Cibie in France. Those two developers were looking into a projector low beam for a more accurate focus and smaller optical devices. In 1986, BMW 7 Series was the first mass produced automobile to have the polyellipsoidal low-beam headlights.

The elements put into a projector headlamp are a light bulb , projector, shield and reflector. The ellipsoidal reflector has filament on one end and a condenser lens on the other. The condenser lens is connected to the front of the lamp. Between the reflector and the lens is a shade that is located at the image plane. As the light from the bulbs is projected, the shade provides a cutoff for the low beam. The shade is shaped and positioned in such a way that the sharpness of the light is controlled. It is also because of the shade that the light gives off a soft blue hue.
Some projector headlamps have solenoid present. If it does, then the shade will have a pivot that is actuated by the solenoid. This pivot provides both a high beam and a low beam. A projector lamp that has this is called BiXenon or BiHalogen.

How it Works
The elements put into a projector headlamp are a light bulb, projector, shield and reflector. The ellipsoidal reflector has filament on one end and a condenser lens on the other. The condenser lens is connected to the front of the lamp. Between the reflector and the lens is a shade that is located at the image plane. As the light from the bulbs is projected, the shade provides a cutoff for the low beam. The shade is shaped and positioned in such a way that the sharpness of the light is controlled. It is also because of the shade that the light gives off a soft blue hue.
Some projector headlamps have solenoid present. If it does, then the shade will have a pivot that is actuated by the solenoid. This pivot provides both a high beam and a low beam. A projector lamp that has this is called BiXenon or BiHalogen.
Xenon or Halogen
Projector lights can come with or without Xenon (a type of gas that gives the appearance of a more crisp illumination). The filament of a projector bulb is so much thinner than that of a normal headlight. This is the reason why it burns brighter. In order to prevent the filament from melting, other gases are needed to alter the gas mixture inside the bulb.
Another form of gas used in projector bulbs is halogen, and is sometimes used instead of Xenon. Halogen is a type of gas; chlorine, bromine, fluorine, astatine and iodine are all forms of halogen gases. A halogen gas is sometimes mixed with krypton inside the bulb.
This, along with the heavy-duty glass or plastic sphere in front of the lamp, is what sets projector lights apart from the other types and defines what they are. The sphere distributes the light evenly across the front of the car, which is why projector headlamps have a bigger range of visibility than other headlights.