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Fog Lights

09/21/2006 2:28 PM

How come nobody knows how to build a decent set of automotive fog lights that really work? I've tried different high and low dollar brands and they really don't cut through the fog, theyr'e just like dim low beams. I'm thinking of a fanned laser at a particular wavelength might do the trick. It's really a b**ch driving in the dark in the morning when you can't see 10 feet with deer jumping out in front of the car..

Whoopee

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#1

Re: Fog Lights

09/21/2006 3:29 PM

LASER is dangerous so as per rule, don't try that. It can easily cut the eye if it is strong enough even to the level of milli watts, while bulb of 1000W may not harm at all.

If you want to see through fog, then use IR LED and IR camera mounted on your head. You can see in nights also. Try night vision camera.

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#2

Re: Fog Lights

09/21/2006 3:54 PM

Please don't use lasers...With a properly mounted set of Hella fog lights you should be able to see fine, you might be mounting them to high. Where are you driving? If you really need some extra light just pickup one of these (approaching drivers will need the shades )

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Guru
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#3
In reply to #2

Re: Fog Lights

09/21/2006 4:06 PM

This may be of some interest

http://www1.cs.columbia.edu/CAVE/publications/pdfs/Nayar_ICCV99.pdf

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#4

Re: Fog Lights

09/21/2006 10:56 PM

The simple answer is... POWER.

For years I used a landing light from a Lancaster bomber hidden behind the 'yoke' of my 58 Edsel. At 48 volts it needed 3 extra batteries to power it and it would set fire to newspaper at 3 feet, but it cut through the worst fogs Montreal could muster and gave me more than a half mile of 'tunnel'.

Back then when the Volvo crowd covered the fronts of their cars with rally lights and tried to burn you off the highway even on clear nights, I could generally intimidate them without going through the entire 30-second warm up. They would usually shut theirs off as mine moved from orange to yellow on it's way to very bright.

I still have the light and may soon be using on the idiots with blue headlights.

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#6
In reply to #4

Re: Fog Lights

09/22/2006 1:28 AM

Awesome, I too love going into the blue light. Let me know if you ever want to sell the light. We don't get alot of fog here but I am interested in bubbling the paint on the hoods of the blue demons.

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Guru

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#5

Re: Fog Lights

09/22/2006 12:29 AM

What you need is a gated image intensifier. Basically it is a night vision device that uses a strobed light. The image tube is gated and the timing is such that you only look at the light that reflects from a certain distance away that you can "tune". Used by the military to see through fog, smoke whatever. Never saw one but I heard it worked well.

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#7
In reply to #5

Re: Fog Lights

09/22/2006 4:38 AM

The gated intensifier would work but the set-up would cost more than your car did. Jaguar have shown a car with infra red vision which sees through fog but I don't know if it made it into production.

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Guru
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#8
In reply to #7

Re: Fog Lights

09/22/2006 6:52 AM

I agree that it will be high cost thing.

IR camera to get image will cost about US$30000 to US$40000 range and then you need a computer and LCD screen to come up for virtual image to drive through absolute foggy and ultralow visivility area. You also need fater image frames to move faster on the road and hence cost may go up lot more. Perhaps, considering the number of cars that may use, the total amount for the equipment may be about US$50000 and not less. It will give you power of a video game.

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#10
In reply to #8

Re: Fog Lights

09/22/2006 8:23 AM

Thank you all for the responses.

I do not take lasers lightly (no pun intended) I presently own a 488nm argon laser

which I use for entertainment purposes and a helium-neon laser which is temporarily out of commision.

I was thinking of mounting 4 inches off of the road aimed no where near the oncoming traffic line of sight, but it seems like I just need a whole lot of incandescent power. The one on the Edsel--How many watts? I have tried the Hellas without too much success. This is a car, so I don't want to mount them on the roof.

I'm wondering if there is a visible light frequency (450-700nm) that is not reflected by water droplets suspended

in mid-air.

I think that driving with night-vision gear strapped to my head may impair my perifial

vision :)

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#11
In reply to #10

Re: Fog Lights

09/22/2006 9:37 AM

Water droplets (fog, vapor, etc) are generally larger than the longest wavelength that you can view with a human eye. Even at 10.6 um, a CO2 laser is greatly affected was water vapor in the air.

A long wave IR system (12 um or longer) will see better thru the fog, then when you view the image on a display, of course, the image is converted back to the visual spectrum you can see with your eyes.

I suspect the reason that the high power incandescents work is that they are high power and HOT.. and thus actually do 'burn away' the water droplets out to a range when the power is dissipated to a level it doesn't work.. ie. higher power the better? *G*

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#12
In reply to #10

Re: Fog Lights

09/22/2006 10:11 AM

I could spend an hour trying to dig up my landing light, but I think it was around 750 watts. It is a sealed-beam, really nicely made, with a completely flat face, very contained beam and a filament that looks like it's 14 gauge wire. It connects with wire braids with screw-on ends, and runs at about twenty amps, at 48 volts. (I know that's more than 750 watts.)

It is more effective in fog than Halogen lamps, likely because the output is 'hotter' - more red and less blue.

As I mentioned I mounted mine behind the grill partly because I was afraid it might be illegal. Positioning is obviously dependent upon vehicle design. (I think if I put it in my F-150 it would melt the grill.)

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#9

Re: Fog Lights

09/22/2006 8:03 AM

Mercedes have a IR camera and dash mounted screen on their new S-class. It improves night vision greatly and apparently feels very intuitive to use rather than being distracting.

I have no idea how well this would work in fog but as an option for a few thousand pounds it's certainly a lot cheaper than the setup suggested above!!

Andrew

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Guru
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#13
In reply to #9

Re: Fog Lights

09/22/2006 12:55 PM

That sounds better, but all cheap camera will be only at best up to 1100nm and not beyond. This sure may help a bit. It is not easy to get faster camera above 2300nm bands as most fo them work on Pyroelectric methods and multiple photon-phonon interaction bases.

If Quantum dot intensifiers are produced then one can get image intensifiers even for greater than 16000nm and the output in visible light, which we all can see easily. Only IR lens may be required which will be most expensive part. Perhaps KCl single crystal lense may work.

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#14

Re: Fog Lights

09/23/2006 8:17 AM

Cibie are what your looking for.

They use Frannel type lens to focus (shape) the light beam so that all the light is at or below the center line of the vertical. This means that the light is not Blooming the fog directly infront out your eyes.

I have seen anything better. I've used them since the mid 70's.

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#15

Re: Fog Lights

09/24/2006 7:38 PM

I like the Lancaster landing light on the Edsel - it's probably creating it's own micro-climate with sufficient warming to dissipate the fog in front of your car - but seriously for any light to be effective in fog it must be mounted as low as possible.

Andy

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#16
In reply to #15

Re: Fog Lights

09/25/2006 7:21 AM

Yeah, an Edsel with a Lancaster bomber landing light.

Too much!

I can almost get a visual image of what that must have looked like...

Like something out of a Stephen King movie

Gotta love it!!!

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Guru
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#17
In reply to #16

Re: Fog Lights

09/26/2006 12:14 PM

I am not sure if you can pump that much energy from a car. It is like firing a heat missile or nepalm bomb to see the road. I think some simple way can be found like ultrasound imager with some 100m range. Use something used to watch fish in the sea. It is Doppler Radar. As car moves, everything else also moves at relative speed so you can scan the road. This may need little power and can provide good black and while image of things on the road.

If you have lots of money and driving a sport car then use costal radar. EM wave can also do the imaging in fog and utter darkness.

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#18
In reply to #17

Re: Fog Lights

09/26/2006 1:05 PM

No, I don't have a lot of cash to spend on this project.

How about focused microwaves to burn away the mist instead of a high power lamp?

(There may be safety issues involved with this approach, I'm sure..)

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#19
In reply to #18

Re: Fog Lights

09/26/2006 10:58 PM

Radiating microwave is not allowed as it can cook the brain of all on the road. Microwave oven are designed for not having leakage of power. If you want to avaporate water in air then it is already evaporated water there. You can gain only by increasing the light intensity, to get back fraction of light back. Selecting a wavelegth helps. If there is smog (smoke + fog) then it is more likely some chemical based and will have specific band. I think www.epa.gov will have some information on this and also www.nasa.gov as they also come across this problem very often.

Perhaps RED light travels much longer in visible zone but gives poor idea of shape. Try Sodium light, which is closer to it. Lower wavelegth towards, green and blue will not travel much due to higher energy absorption and scattering. Yellow Sodium light may be a problem for color blindness. Hence, Mercury and Sodium mixed power may be much better. Helogen lamps are often used, but Sodium lamp is more efficient.

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#20
In reply to #19

Re: Fog Lights

09/27/2006 8:12 AM

Thanks Shyam, I'll try to find a 12 volt sodium light. I suppose what I'll find will be 120/240 volts AC and need a ballast. I'll probably use an inverter if the current is not too high, and it can handle an inductive load.

As far as the microwaves go, I was thinking of a short range/ wide dispersal /low power setup

that won't cook anything, just clear the fog out a bit...but the sodium light sounds better.

As far as smog and chemicals go, I live in the southwest virginia mountain area U S, so its pretty much just thick H20 fog.

Thanks for everyone's input and thanks to the CR4 team.

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#21
In reply to #20

Re: Fog Lights

09/27/2006 12:49 PM

Sodium lamp does not start working immediately. Sodium needs to be evoporated by heating method and that takes time. Sodium in vapor state can be ionized to yield two very close yellow lines. This may take time and you should never switch OFF the lamp while you need it, else you will have to wait for minutes for the lamp to warm up.

Output intensity of the Sodium lamp may be about 4 times to the mercury lamp light efficiency. 250W Sodium lamp will be highly powerful and will give visibility of 50m-100m even in dense fog. Perhaps two Sodium lamps will be just great. Sodium lamp will also not hurt the vision of the in coimg driver.

You can use that silver reflector housing for the ready made Sodium lamps. People often put these as extra lights and they are also used on Police Vans with lots of Yellow light reflectors. In fact they give great look.

Sodium lamp also come blended with Mercuty in it. Blending with mercury will avoid accedent with color blind driver. Some people can't see some colors so they may be seeing nothing when you put Sodium lamp. This may sound funny but is the truth of the nature. Some will see it as different color than yellow so no problem as they will see you some how. Not seeing is worst as you will be an invisible man for such people.

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#22
In reply to #21

Re: Fog Lights

09/28/2006 7:38 AM

I am having trouble locating miniature high pressure sodium bulbs.

Do you have any links or sites?

Thanks

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Guru
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#23
In reply to #22

Re: Fog Lights

09/28/2006 8:58 AM

I think you can get them everywhere. They are Ostrich egg shape bulbs and you can hold them in hand. They are not so big. Just go to some lamp store and you should find them. They are also used for street lights with yellow color. I am in India so my local addresses may not be of much use.

You may like to read this

http://scienceservice.si.edu/027084.htm

http://www.nextag.com/high-pressure-sodium-lamp/search-html

http://www.lamptech.co.uk/Documents/SO1%20Introduction.htm

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