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CES: Laser Headlights Edge Closer To Real-World Highways
jeffb (2.718) writes "Audi will display laser-headlight technology on a concept car at the 2014 Consumer Electronics Show, joining BMW, whose plug-in hybrid should reach production in 2014. A November article on optics.org describes the technology in more detail. This approach does not scan or project a 'laser beam' from the car; instead, it uses blue lasers as highly efficient light emitters, and focuses their light onto a yellow phosphor, producing an extremely intense and compact white light source and then forming that light into a conventional headlamp beam. The beam isn't coherent or point-sourced, so it won't produce the 'speckling' interference effects of direct laser illumination, and it won't pose specular-reflection hazards. It's just a very bright and very well-controlled beam of normal white light.
HID lights are illegal to retrofit on any road-going vehicle not originally equipped with them in the USA for just that reason. They really do need an active aiming system that is careful not to shine the beams at other vehicles.
Technically, the Xenon/HID retrofit kits that put the lamp into your existing headlamp housing are illegal. If you retrofit by replacing the entire headlamp assembly, then it is legal. This is due to the differences in the optics required to achieve the required illumination pattern. You can not achieve a legal lighting pattern when you install a xenon lamp in an incandescent housing, it just doesn't work.
A Halogen lamp produces its light over a (short) line, while a xenon lamp is much closer to a point source of light. As such, the optical design of the lenses/reflectors is significantly different.
...si hoc legere nimium eruditionis habes...
Perhaps actually try it? All car mirrors have a second mirror behind the first, at precisely the angle that the switch adjusts by. When being followed by a car with bright headlights, flick the switch and you'll observe that you get a much-dimmed version of the same image. At night, you'll perfectly well be able to make out the car behind you.
Well, not quite... On manually dimmed rear-view mirrors, what you're actually doing is switching to the surface reflection off of the glass, rather than the reflection off the silvered surface. On average, standard glass will reflect about 4% of the light striking its surface. The glass used in rearview mirrors is manufactured so that it's ever so slightly wedge shaped. During normal use, the reflection off the silvered surface dominates (and the 4% gets aimed down at your chest), but when you flip that little tab on the mirror, it aims the silvered reflection up into your car's headliner, and puts the front surface in its place.
This is also the reason why it's bad to have any kind of lighting (computers, DVD players, reading lights, etc... ) going in the back seat, especially if you have a light coloured headliner... It's pretty easy for the glow on the headliner to overwhelm the reflection of what's behind you.
...si hoc legere nimium eruditionis habes...
BULLSHIT. This is a lie you tell yourself to justify what you did to your car.
Stock Audi's, BMW's and more are all blinding other car drivers. In an urban environment the HID lights are somewhat balanced by the ambient lighting and several-per-block streetlights; in a suburban or highway environment the reduced frequency of streetlights makes their giant light contrast more dangerous because the eye spends more time adjusting and readjusting between dark and blindingly bright.
It's much worse for car drivers when these are on SUVs or trucks. Even in the rare cases when the lights are adjusted for those vehicle's increased heights, that's no help when the assholes pull up behind you at a light.
Bullshit indeed, Captain Clueless AC.
HID-equipped cars don't use traditional aiming lenses. They use a projector ball in front of the bulb which shapes the light emitted. Additionally, between the bulb and the projector there's a metal cut-off plate that prevents light from being thrown upwards. While HIDs typically emit about three times as many lumens, virtually none of it is permitted to aim towards oncoming traffic.
The point Lumpy was making is that proper projector housings cost serious money while a set of HID bulbs and inverters cost in the realm of $50. Yes, many, many ricer idiots retrofit HIDs into their cars unsafely by keeping their lens-based housings. Which means... three times as much light in oncoming traffic.
Now you know, which should help you to stop being uneducated. Or you WOULD know if you'd not posted AC and got a nice notification someone replied to you.
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