Not really sure what to make of this, other than it seems pretty odd. Though I’m sure they said the same thing about LEDs being used for lighting even a room in your house a few years ago.
$$ Cha-ching $$
Not a good idea. Laser light is coherent. That means it is one frequency and completely in phase. Even very low levels of coherent light can cause serious damage to our eyes. Instead of being spread across a spectrum of frequencies like regular light so that the sensors in our eyes can spread out the absorption, laser light concentrates on one set of receptors that must absorb all the power.
Its like the difference between being hit by a brick vs. being hit by a sharp knife, both with the exact same momentum. Its much easier to absorb the shock of the brick.
Pretty soon, the driver will become blind to that particular frequency of light and wont be able to see anything reflected from his own headlights. He will still be able to see most other frequencies of visible light.
I have personal experience with this. I was doing some demonstrations using a Helium-Neon laser, 0.1 watt output. I had split the beam into about twenty separate beams and one of them hit me in the eye. It was only for a fraction of a second but it left me red blind for the rest of the day. due to low power and limited time exposure, I was OK the next day.
I don’t think it’s a good idea either. Can you imagine a malfunctioning headlight laser hitting your rearview mirror? Drivers have been blinded for years with approaching headlights from the front and the rear. Lasers will add a whole new dimension of danger to the mix.
I doubt that eye exposure will be the main concern. It’s certainly possible to diffuse the emitted light so that it’s harmless. But I’m not sure what the point is either. Headlamps are already plenty bright, and HID lights do a great job and without blinding oncoming motorists.
I’d be mostly worried at the >$1000 repair bill to replace a headlight on your BMW. But with BMW having the bright idea of eliminating the oil dipstick on some models, it seems like a natural progression of insanity.
As a side note, imagine if it would be possible for one of these to malfunction and emit a beam of coherent light. Not only would oncoming motorists be at risk, but if the beam reflected off a mirror or other shiny surface of a car in front of the BMW, it could easily blind the driver as well.
It’s already coherent light as mentioned earlier. There are already lasers used where eyes are a concern and they use various techniques to make them eye safe. The “lens” would be a filter if necessary. I just don’t see the need for increased visible light and the cost/benefit tradeoff is not good IMO. Now if they want to revisit the NIR w/heads up display- that’s something I feel would be a great feature to make more commonly available.
If you filter out coherent light, then you have no light. If you diffuse the beam, which the lens will have to do anyway, it does not make it less coherent. It will still blind you to that specific frequency or wavelength. It takes a very small amount of coherent light to do a lot of damage.
C’mon Keith, this shouldn’t be confusing. The issue of eye safety was brought up. The laser will be designed to emit in a safe region. For out of band energy, a filter will eliminate those wavelengths or at least knock them down to a safe level. Coherent light in of itself is not determining of eye safety, it is the wavelength and energy of the source.
I agree with Keith on this. Coherent light that is within the visual spectrum is dangerous to the retina. It’s a highly concentrated energy. Coherent light in a “safe wavelength”, a wavelength that does not activate the retina, is invisable and would not be usable as a headlight. Note that I know I’m using the term “light” (normally used for only energy in the visual spectrum) a bit loosely here.
In addition, light sensitivity is commonly associated with age-related eye diseases, and the population is definitely aging. Having incandescent bulbs come up over the road’s crest is bad enough, having HID bulbs do the same is worse. Getting hit in the eyes with a laser would be, I imagine, a real pain. Lasers are great for eye surgery, not for headlights.
As I write this I’m beginning to wonder how laser headlights will affect visability of colors. Lasers operate in a specific frequency. Although I have to wonder if BMW is actually designing a night vision system. If they were to use lasers to “paint” a picture in the dark and then convert that to a night vision display, perhaps in a “heads up” application, and then mix that with the LED reflected light “picture”, they may have something good here. Probably expensive, but good.
I don’t like the idea for several reasons.
A bright line spectrum light (think of those orange lamps on the freeways) only provide a small range of light color. When you do this you don’t get (see) illuminated objects nearly a well by a light of the same color. It is a problem with those HID headlamps.
We use not only the amount of light, but also the color of the light in everyday viewing.
Our technology is improving, but what you are talking about is just not a good idea.
OK, I saw the link to the actual press release. They are using the laser as a source to excite a fluorescent coating on the inside of the headlamp. In other words, this is going to be a high tech CFL. I don’t have the bandwidth to do the video, I’m on a satellite.
Thanks Keith. I had a feeling I was missing something.
As to my feelings on the new technology, I don’t have the budget. Nor do I see the advantage. And I’m puzzled why everyone is in such a rush to switch over to bulbs that use mercury vapor.
It won’t use mercury vapor, that part of what the laser is for. What gets me is taking big car with a bigger engine and then worrying about the efficiency of the light bulbs, especially going from LED to this new light. They are trying to save fuel. If they are really serious about saving fuel, I think they need to look just behind the headlights.
What you say about the mercury vapor makes sense.
I agree with your other statements too, but the nut behind the steering wheel is the only one in a vehicle that cannot be fixed.
I have to abashedly admit that I’m one of those nuts. I just made some intake system modifications that have cost me over 2 mpg. The gain in highway power is definte and noticable. I could return it to the original configuration, but I love the extra power. Of course, I could retrain my right foot…but I’m having too much fun feeling young again.
From Keith
“OK, I saw the link to the actual press release. They are using the laser as a source to excite a fluorescent coating on the inside of the headlamp. In other words, this is going to be a high tech CFL. I don’t have the bandwidth to do the video, I’m on a satellite.”
That sounds interesting. I suspect it may still have the “bright-line” effect, but it may not. I will have to watch to to see if there is more on this.
I think that there would be optics to diffuse the light so that it would throw a wide beam rather than the pencil-thin laser that we are used to. Surely a professional automaker like BMW would thoroughly test the laser headlights before deploying them on their new cars. Back to the wide beam: not as wide as the lamps we have today, but narrow enough that they would push the visibility zone.
jt, its going to be a fluorescent light bulb, not a laser light. In todays florescent bulbs, a stream of electrons passing from one end of the tube to the other excites the phosphoric coating on the bulb. The BMW bulb will use a laser beam instead of a stream of electrons to excite the phosphors. The light from the excited phosphors is non coherent and omnidirectional. It will need mirrors and focusing lenses just like todays bulbs.
BMW thinks these bulbs will be more energy efficient than even todays latest LED bulbs.
That’ll teach me to read the posts and not the article!
Maybe they’re gonna test this alongside the laser spark plugs we’ve heard about
I agree with Keith on this. Coherent light that is within the visual spectrum is dangerous to the retina. It’s a highly concentrated energy. Coherent light in a “safe wavelength”, a wavelength that does not activate the retina, is invisable and would not be usable as a headlight. Note that I know I’m using the term “light” (normally used for only energy in the visual spectrum) a bit loosely here.
TSM, I apparently gave you more credit than you deserved! 
Let’s use one easy to cite example to illustrate my point and refute your assertion that ANY coherent light is damaging to the retina. Laser pointers are both spatially and temporally coherent light. Below 1mW, there is absolutely no risk to the retina and you can stare into that beam all day long with it pressed up against your eyeball if you so choose. That is a class IIIa laser and at even moderate power, can be damaging to the eye. So the only difference between the two is the POWER LEVEL of the emitted light. If coherent light is inherently dangerous, how do you explain this?
Excerpted from: Laser safety - Wikipedia
*Van Norren et al. (1998)[22] could not find a single example in the medical literature of a <1 mW class III laser causing eyesight damage. Mainster et al. (2003)[23] provide one case, an 11 year old child who temporarily damaged her eyesight by holding an approximately 5 mW red laser pointer close to the eye and staring into the beam for 10 seconds, she experienced scotoma (a blind spot) but fully recovered after 3 months. Luttrulla & Hallisey (1999) describe a similar case, a 34 year old male who stared into the beam of a class IIIa 5mW red laser for 30 to 60 seconds, causing temporary central scotoma and visual field loss. His eyesight fully recovered within 2 days, at the time of his eye exam.