Lasers, xenon, diodes (LEDs) – first of all, by these terms we mean light sources, i.e. lamps. But in the case of a car, we shouldn’t talk about lamps separately, but about an integrated optical system – headlights – otherwise, you won’t get full road lighting. This, in fact, should be discussed in more detail.
How a modern headlight works
A car headlight of any type (there is one exception, but more on that below) has three main elements: a light source (lamp), a reflector-reflector, and a glass diffuser. The lamp provides light, and the rest of the parts shape it into a beam of the desired shape. And the role of the last two elements can be different: sometimes the reflector is the key, sometimes the glass is almost the only thing that makes the difference, which, by the way, is often not glass but plastic. But in any case, the lamp is the most important thing – if it is weak, you will never get an acceptable beam.
Another important factor in the efficient operation of a car headlight is the absolute integrity of all its components. Unlike other vehicle systems, a damaged headlight will not work properly, and may even endanger the safety of other drivers. The main condition here is the exact position of the lamp in the headlight relative to the reflector and diffuser. After all, the point of light emission – for example, the spiral of a halogen lamp or the LED chip of a diode lamp – must be located strictly at the focal point of the optical system. If the lamp is out of focus for some reason, the headlight will not illuminate the road properly, but will instead blind other drivers, including those on the road.
Halogen lamps
To begin with, we must mention the good old incandescent light bulbs – what we now call halogens. They emit light from a filament of refractory metal that is heated by an electric current. Halogen lamps became halogen when their bulb was filled with an inert gas, halogen. This technology increases the efficiency of the lamp while maintaining its service life.
Halogen lamps are inexpensive and technologically advanced, can be connected without additional starters, are not afraid of voltage and temperature fluctuations, and can be easily adapted to any optical system. The disadvantages are low efficiency, about 5-15%. Thanks to the new technology of increasing the pressure in the bulb from 5 to 12-13 bar, it became possible to produce models with standard consumption, but with increased light output: +30% brightness, +50% and even +100%. The best halogens have a lifespan of up to 1000 hours, while more or less mass-produced high-quality ones have a lifespan of no more than 400 hours.
Xenon
In technical terms, these are gas-discharge lamps, in which light is produced by an electric arc ignited between a pair of electrodes in an atmosphere of inert gas, xenon. Compared to halogens, such a lamp consumes almost half the current, but its luminous flux is two to three times higher. A branded discharge lamp lasts longer than a typical halogen lamp. Another positive is that its light spectrum is close to daylight. There are also many disadvantages: high arc temperature, which causes the lamp to burn out the reflectors of standard, non-specialized optics, the need for ignition units and an additional dynamic beam correction system. Xenon lamps are frankly expensive; a high-quality set with starter modules and appropriate optics costs about a thousand dollars.
LEDs
In LED lamps, light is produced by a semiconductor chip that requires two to three times less energy than incandescent lamps. Another significant advantage is durability (up to 100 thousand hours). Today’s LED headlight bulbs are connected to the mains without additional units. It is important that it is possible to create an LED lamp in the size of a conventional halogen lamp (H4, H7, etc.), which means that you can easily use diode light in standard headlights. However, it should be an exceptionally high-quality lamp from one of the world’s two or three leading manufacturers who have learned to produce LED chips no larger than a halogen spiral. At the same time, cheap analogs do not fall into the focus of the optics and do not provide normal lighting, but instead blind everyone around.
Laser headlights
The newest lighting technology today is laser. In these headlights, the road is illuminated not by the laser itself, but by a fluorescent substance that the laser “pumps”. In addition, a special set of lenses and micro-mirrors collects the light from many individual “pixels” and directs it onto the road.
The main advantage of such headlights is their high light output, as the brightness is twice that of LED headlights or xenon. The laser beam reaches 600 meters, but because of its brightness, it is advisable to use it only with the aforementioned matrix technology. Laser headlights can be made small, they heat up less than LED headlights, and last as long as they do.