Idea for car head lights - why doesn't this already exist?

I've got an idea for vehicle head lights, that seems simple enough and, in my mind, has great benefits, but does not, to my knowledge, exist (yet). Unless someone here can point out why this idea is dumb or won't work, I think I'm going to build a prototype.

Here it is: front windshield tint, that doesn't diminish the brightness of your headlights for night driving, but does block other driver's lights, and blocks sunlight for daylight driving.

Pretty simple really. I've got some headlights currently on the Little Lamb-orghini http://www.littlelamborghini.com that when turned all the way up make well over 14k lumens. That is effing bright. This is all well and good as long as you are behind them, but pity the fool who approaches an oncoming vehicle with 14k+ lumens on the grill. So I could make do just fine with half that much light. So apply a linear polarizing film to all the lights, and I only get the vertical wave light out of the headlights, and essentially half the light output. Now, I still have the issue of oncoming traffic's lights, the blinding sun, and the occasional distracting light from an alien abduction. Some window tint would be nice, except that I wouldn't be able to see where I'm going at night, right? No problemo though, just install a vertical linear polarizing film on the windshield. Half of all the light from outside the car will be blocked... EXCEPT for your headlights, which, already being linearly polarized the same orientation will pass right through the windshield with virtually no loss in intensity.

Obviously, orientation of the film is important for this to work. Put the polarizer on the headlights sideways and NONE of the light coming out of them would be visible through the windshield.

Yeah, polarizer seems a bit expensive, until you go to your local recycle center and see all those LCD big screen TV's and computer monitors, all of which have a linear polarizing film in them to make them work. Or you can buy the stuff, it's not prohibitively expensive relative to some things we put on cars, Enough to cover the windshield will set you back $200-$300.

I've already got one response for 32" worth from this ad: http://evansville.craigslist.org/wan/3536268631.html And I think 16VCorey may have some scraps for me as well.

They experimented with polarized headlights back in the 50s or 60s. I remember reading that while it worked it just wasn't practical from a cost standpoint, and it didn't work "that" much better to warrant it.

Then you could make 3D traffic signs and signals.

Sounds like a good candidate for a kickstarter project...

A few hundred bucks to cut all external glare in HALF? Granted visors are cheaper, but they're always falling down stuff. It doesn't seem that expensive to me given the benefits. And the added benefit of having a polarized surface the length of the windshield for bouncing your HUD off of (but that's a different topic all together).

N Sperlo wrote: Then you could make 3D traffic signs and signals.

Or even so it looks like the other cars are coming right at you!

N Sperlo wrote: Then you could make 3D traffic signs and signals.

Only if you had half of the windshield polarized one direction and the other half in another...

Well the big problem I see is that not being able to see an oncoming car's headlights at all isn't a good thing...

Can't light change polarization after reflecting off stuff? So after you lit up a stop sign you might not see the reflection?

In reply to GameboyRMH: I believe they would only be at half-brightness, not completely gone.

To make it work best, you'd want the polarizing at 45 degrees and on every car. That way you'd see your headlights but approaching lights would be blocked. Or heavily attenuated, anyhow.

Aren't some vehicles windshields already polarized?

Also, just get light brown polarized sunglasses......they're essentially blue blockers at night, plus you can laugh at GM minivans for having solid blue windshields in the daytime

What happens when the oncoming car has headlights that are polarized the same as yours?

So you mean that the windsheild would dim the bright spot much like some sunglasses dim in bright light...

In reply to yamaha:

Part of the story not told is that I need a polarized windshield anyway to fix some of the ghosting I get on my heads up display. But yeah, sunglasses should do the job as well as long as they're polarized in the right orientation. And I can fit them under my helmet (got to make this work for LeChump races too) Of course I'm blind without my prescriptions, so I'd have to have prescription polarized glasses, or get some bitchin' clip ons.

And just something about cruising around in sun glasses at night that seems a bit... well, nevermind. That part would make me look cool. Especially with clip ons.

In reply to Sky_Render:

Then it would be no worse than it is today without the tint

So all you would need is all of the car companies to have a standard that they all follow the exact same (which happens to increase cost significantly for every single vehicle made) and would make it much harder to see any vehicles and lights that aren't following the same standard?

Sounds brilliant, let us know how it pans out!

Bryce

naw, it should still work (better) if I've got the only car on the road doing it. If they have light polarized like my headlights, my windshield tint does virtually nothing for to block their glare. Still works for sunlight, and other cars tho.

One of the problems is that DOT won't approve it for one reason - No one has come up with a polarizing film that doesn't block significant amounts of light. They are a pretty dark tint since they basically absorb about 30% of the light rays (that is, the light rays that hit the polarizer nearly perpendicular to the orientation of the polarizing axes).

Any tint on windshields or headlights is a big no-no.

I think its a great idea with potential, but you'd have to prove that potential to NHTSA, which might take a multi-million dollar R&D budget. You might be able to build a prototype and then sell it to an auto maker. If you show them that it can be done, they might be able to see the profit in it and buy your idea. Then its THEIR problem to get it past NHTSA.

curtis73 wrote: One of the problems is that DOT won't approve it for one reason - No one has come up with a polarizing film that doesn't block significant amounts of light.

Ray Ban has. My sunglasses are polarized and clear inside in dim light, dark as night out in the sun.

Windshield is already tinted maximum amount allowed by DOT from factory from every manufacturer I know.

There are films you can place on your front windshield now that are already for sale. very popular in Texas/Arizona/New Mexico. These films do not reflect (not absorb, tint does not absorb, if it did your windows would glow) light but filter the UV spectrum.

I am not sure this was your exact idea, but I think the legal possibilities on front windshield treatments have been explored.

Unless you know some legislators that will craft a very closely worded bill to prevent anyone but you from doing it, it's been done.

Yeah, I hear ya. Tint on the windshield may not be legal (but I'm 99% sure I've seen gangster tint on windshields cruising through my town, as I have seen blacked out or smoked headlights a plenty). Though I can argue that the intent of the law is met with this concept the letter may not be, so making it a 'product' would be a real PITA, but installing it on my own personal vehicle I'd expect I could get away with unless I really whizz in a state patrolman's Wheaties.

Same concept, but put the polarized film on my helmet visor or glasses, totally works, totally legal. Well, if wearing a helmet in a car is legal...

I've got a plan 'B' for my HUD anyway that I think is going to work better than what I brought to the GRM challenge anyway, so my first reason for putting polarized film on the windshield may be moot of plan B works. Plan B involves some sample materials from these guys: http://superimaging.com/ , and a modified pico projector. Basically turning my helmet visor into Google Glass for less than the cost of dinner and a movie. Or at least that's how awesome it is, in my mind.

Just a CRAZY thought...But why not simply install non-overpowered headlights for road use??

This idea also seems to assume that the headlights provide all of the useful lighting in dark conditions and that the reduction in ambient lighting through the polarized windshield will not have any effect on night time driving visibility. While this may be true for back country roads in the middle of nowhere on a moonless night, it certainly does not hold true much of the rest of the time.

Giant Purple Snorklewacker wrote:

curtis73 wrote: One of the problems is that DOT won't approve it for one reason - No one has come up with a polarizing film that doesn't block significant amounts of light.

Ray Ban has. My sunglasses are polarized and clear inside in dim light, dark as night out in the sun.

Didn't know that, but... it kinda proves my point... it doesn't matter WHAT light is allowed through, if it restricts light of any kind, it most likely won't pass DOT.

Your Ray Bans... not photo-sensitive?

curtis73 wrote:

Giant Purple Snorklewacker wrote:

curtis73 wrote: One of the problems is that DOT won't approve it for one reason - No one has come up with a polarizing film that doesn't block significant amounts of light.

Ray Ban has. My sunglasses are polarized and clear inside in dim light, dark as night out in the sun.

Didn't know that, but... it kinda proves my point... it doesn't matter WHAT light is allowed through, if it restricts light of any kind, it most likely won't pass DOT.

Stahp!!!!!

Flight Service wrote: Windshield is already tinted maximum amount allowed by DOT from factory from every manufacturer I know.

but since you need semantics.

U.S. glazing summery and link to PDF for NHSTA regulations and ANSI and SAE standards.

also look for glazing not tint