"Halogen" "HID", "LED" & "Laser" Headlights...What's Different?

It wasn’t that long ago that headlights were a no-thought-required feature. All cars had them and no one really paid them much heed unless they failed or were shaped in a particularly ugly manner. View more details after the cut…

Halogen

Reliably generating light with the limited resources at a car’s disposal was a problem for early automotive engineers.

Tungsten filaments, similar to the kind found in household incandescent light bulbs, were finally settled on as the solution. From the mid-1960s until now these tungsten filaments have been encased in a bubble of halogen gas in order to improve performance and longevity. Combing low cost and a working life of between 500 and 1000 hours, halogen bulbs are the most common headlamp type in use today, although that is rapidly changing. Spurring things along is the desire of car makers to improve efficiency. Halogen bulbs draw around 55 watts of power, and much of that is wasted as it’s converted into heat rather than light.

High Intensity Discharge

In high intensity discharge (HID) headlights, such as those used across the Lexus IS range, a mixture of rare metals and gases are heated to produce a bright white glow. HIDs are around two to three times brighter than halogen lamps and their glare can be particularly annoying for other road users. As such, the Australian Design Rules require cars equipped with HIDs to also have a self-levelling mechanism and a headlight washer. The former ensures that the headlights are always aimed towards the ground. The latter minimises the build up of dirt and grime, both of which can divert more light into the eyes of on-coming drivers.

LED

Whether you realise it or not, they provide most of the lighting used in today’s instrument panels, entertainment head units and car interiors. As well, arrays of these diodes are employed in fog lamps, indicators and brake lights. Car designers love LEDs because their small size allows them to be fashioned into ever thinner and more distinctive shapes.

Although LED headlights currently fall a little short of the brightness achieved by HIDs, they hit maximum brightness within a millionth of a second compared with the half second required by incandescent and halogen lights. Touch a halogen bulb or xenon globe when it’s on and you’ll likely recoil in pain from the intense heat, but with LED headlights you’ll struggle to break a sweat. Therein lies their great advantage, they convert most of the energy directed to them into light not heat. In fact most of the heat generated by LEDs is at their electrical base, not on the bulb surface.

Laser

The tech relies on a rapidly moving micro-mirror that redirects the beam from an Osram laser, which starts as a 450-nanometer blue beam that is converted to white light via a fluorescent filter. "The mirror used for this, which comes from the Bosch company, is a micro-optical system that features electro-mechanical control and is based on silicon technology." It is very sturdy and exhibits very long life. Such components are also used for accelerometers and control units for electronic stability control. The light will feature in some of the next generation cars.