The use of bi-xenon lenses, where one lamp is used as a light source for high and low beam, began in the late 90s. Switching to high beam is accomplished by lowering the curtain, which “cuts off” glare when using low beam. The curtain is lowered by an electromagnet when voltage is applied to it. When the feed stops, the curtain returns to its original position using a return spring. But this design complicates and increases the cost of the lens module, therefore, automakers do not use this design in all models where lens optics are installed.
Since the late 90s, lenses have undergone many changes. The materials used to make the reflector, the shape of the lens glass, the quality of surface treatment, and the type of curtain have changed. But, nevertheless, fundamentally, nothing has changed in the lens design itself.
Lens modules received further development in 2003, when adaptive road lighting technology began to be used in headlights. The modules in the headlight have now begun to move not only up and down, but also to the right and left. This design allowed the light to “look” around the corner, as it were. That is, when turning the steering wheel at speed, the headlights began to turn towards the curve of the road, which significantly improved driver comfort. Adaptive light is a complex system that takes information from several sensors - speed, steering angle and many others installed on the car, and then, using a computer, controls the angle of rotation of each headlight individually. As you can see in the diagram below, the angle of rotation of the right and left headlights is always different.
Smart optics has become the next stage of development. When cameras appeared on the car, the computer now had the ability to timely detect the appearance of oncoming and passing cars and turn off the high beams.
Next, in 2006, multi-mode light beam technology began to appear on premium cars. The computer has now begun to take into account an even greater number of parameters, including the number of cars around. In such lens optics, they began to use not one curtain, but a drum, or a set of several curtains. As a result, the headlights became multi-mode.
But, apparently, lens optics have reached their limit in development, as manufacturers began to use LEDs in headlights. LED headlights use several light sources and, thanks to the precise distribution of brightness on each of them, there is no need for moving parts, which previously greatly increased the cost of the design and had physical wear and tear, resulting in breakdowns and failure of the entire system. LED headlights also no longer use reflectors and lenses. The technology of using LEDs now makes it possible to selectively either illuminate or darken different sections of the road.