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I would like to know if a very bright light will attract an incoming laser guided weapon such as a laser guided missile.

Say for example that a tank has a six-foot pole on the top of it and attached to the end of this pole is a high-voltage carbon arc lamp and it emits light in all directions. I am wondering if the intense light of a carbon arc lamp will outshine the reflecting laser light coming off the surface of the tank and the incoming laser guided missile will steer itself towards the carbon arc lamp.

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Can a very bright light attract an incoming laser guided weapon?

I want to point out that I am not an engineer and I know very little about how laser guided systems work, so I am asking this question simply out of scientific curiosity.

user57467
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2 Answers2

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No. It might blind it but it would not attract it.

Laser guided weapons aren't just laser versions of heat-seeking weapons. You would modulate the targeting laser so that it could be differentiated even in the presence of another light of the same wavelength.

And if the missile has optical filters (which it will) they will just prevent most of the light at irrelevant wavelengths from ever getting to the sensor to saturate it. That would mean that your arc light would have to emit enough light specifically at the pass-gap and to saturate the sensor.

DKNguyen
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    What you said makes sense. This now makes me wonder if the brightness of a carbon arc lamp would make it difficult for the person pointing the laser at the tank to clearly see the tank and to keep the laser pointed at it. For example, the person's eye may have trouble staying focused due to the bright light. – user57467 Mar 15 '22 at 21:24
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    @user57467 sunlight have enough wavelength difference from arc lamp it should be possible to just filter them if it ever becomes commonplace https://www.researchgate.net/figure/Spectrum-of-enclosed-carbon-arc-lamp-and-sunlight-8_fig1_297682159, but this would only work on close enough range, the same reason infantries doesn't pop out bright light to blind snipers. Targeted laser works, but if you can pinpoint the sniper accurately, you send artilleries, not light. – Martheen Mar 16 '22 at 03:31
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    @Martheen Sending bright monochromatic focused light is becoming a thing. – Russell McMahon Mar 16 '22 at 07:39
  • @RussellMcMahon Dazzler? Great for CQC, but how much watt on open areas? Plus, if you have the location, why not just spray it with good ol' lead? – Martheen Mar 16 '22 at 07:43
  • @Martheen I was thinking of a LASER response. Pros and cons. – Russell McMahon Mar 16 '22 at 07:52
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    @Russell's approach could dazzle the sensor as a direct beam will be far brighter than the reflection off the target, even making the beam slightly divergent and aiming/delivering photons at a fast-moving missile is far easier than aiming bullets at it. "Far brighter" means the modulation of the targetting laser is lost in the noise, or the detector is saturated and reading max value for all pixels at all times. I can't instantly find what wavelengths are used for guidance but it will be a small list – Chris H Mar 16 '22 at 10:42
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    There's a lot of history here, and yes early optical guided missiles might have been distracted this way. Since the advent of solid-state imaging chips, things like anti-tank missiles use image processing for the final approach so they can precisely hit points like the turret-body interface. – Carl Witthoft Mar 16 '22 at 15:20
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    It seems to me that the Hedy Lammar anti-jamming solution for guided torpedos is relevant here. – JimmyJames Mar 16 '22 at 20:51
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    This means that an arc lamp is specifically useless: It emits light that is heavy in blue and UV radiation, totally breaking camouflage in the visible spectrum, while emitting preciously little IR light. I guess that most targeting lasers use IR light, as IR lasers are much easier to produce and there light is easy to handle optically. So the guiding camera would only sees the arc lamp as a tiny, dim spot right next to the bright, monochromatic, correctly modulated spot created by the guiding laser. – cmaster - reinstate monica Mar 17 '22 at 08:52
  • @JimmyJames that was frequency hopping wasn't it? That's harder to do optically – Chris H Mar 17 '22 at 11:47
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    @cmaster-reinstatemonica I thought carbon arc lamps had a few very strong, but very narrow IR spikes. – DKNguyen Mar 17 '22 at 13:15
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    @DKNguyen That may be the case, I don't know the details of their spectrum. What I do know is that they predominantly produce thermal radiation from heating a very tiny speck of air to very high temperatures. And that does not produce much IR radiation. And even if you have some super-termal IR spikes due to quantum effects, you cannot assume that they will be close enough to the laser's wavelength to blind the guiding optics. – cmaster - reinstate monica Mar 17 '22 at 13:35
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    @cmaster-reinstatemonica Yes, their narrowness and intensity would be hit or miss. – DKNguyen Mar 17 '22 at 13:36
  • @cmaster-reinstatemonica, so, would it be safe saying that a high-voltage. unshielded IR heat lamp, having a 1000 watt bulb that shines IR radiation in all directions, would be more distracting to an incoming laser guided missile? – user57467 Mar 17 '22 at 15:24
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    @user57467 What you'd need would be a heat radiator, i.e. a large, red glowing surface. That would provide you with much more IR blinding capability per watt than an arc lamp. That said, the argument about modulated, narrow band lasers still applies: You'd need insane amounts of IR power to blind laser optimized optics. You best defense would be a tunable counter-laser and broad-band laser detection optics with an inbuilt spectroscopy to quickly select the correct wavelength for the counter-laser. Not simple, but definitely within the realm of possible. – cmaster - reinstate monica Mar 17 '22 at 16:11
  • @ChrisH You could be right, I wouldn't really know. But there are other ways you could encode encrypted signal in light. The mechanism would be different but the principle the same. – JimmyJames Mar 17 '22 at 17:26
  • @JimmyJames yes, by modulation, which was already discussed - that is done, helps a lot, and is in fact necessary when you might get things like changing reflections of sunlight. What it can't handle is overloading the sensor - imagine a unique binary pattern identifying the laser, but then countermeasures are bright enough to force the sensor output to just read 11111... – Chris H Mar 17 '22 at 17:29
  • @cmaster-reinstatemonica rather than a tunable counter-laser, just a few separate emitters at the right wavelengths. There won't be many. – Chris H Mar 17 '22 at 17:32
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    @user57467 it's really worth going for a beam or a narrow cone, for a few reasons - to avoid making your position even more obvious, to avoid dazzling your own/comrades own optics, and to put the light in the right place. A 1° cone is pretty broad at km ranges, but about 40,000 times more efficient at illuminating the target with the same brightness – Chris H Mar 17 '22 at 17:36
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Probably not.

Look, anything is possible. You could throw some rocks at a keyboard, and have it open SE, log in, and post an proof of trisection.

It ain't real likely.

Laser guided weapons usually have some specific frequency they're looking for. Then, on top of that, the laser is pulsed as an identifier (think of it spelling four letters in Morse code on a loop — not how it works, but a good analogy).

To misguide your missile, you're looking at the narrow band of light you're looking for coming off the arc lamp, then flickering in a way that duplicates the "Morse code" the weapon is looking for. That's... unlikely.

More plausible is that you can put out so much light that you blind the missile, and it doesn't hit anything. Of course, the more traditional way to do this is with another laser that you shine back at it - much lower power cost; far fewer friendly effects.

fectin
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    So, you are saying that the carbon arc lamp would have to pulsed at the same frequency/modulation of the tracking laser. That's interesting, yet I imagine the frequency/modulation of a laser would be pretty high and I wonder if a carbon arc lamp would be capable of producing such a high frequency. It's something I'll have to research. – user57467 Mar 16 '22 at 23:14
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    @user57467 Not just frequency but the same "code". In combat it's possible to simultaneously target multiple targets with multiple lasers and launch multiple bombs and none of the bombs will go to the wrong target. It's like, the laser is spelling "LOOK-I_AM LAZER:NUMBER=22" and the bomb is looking for a laser signal that is broadcasting "LOOK-I_AM LAZER:NUMBER=22" and ignoring the one that says "I_AM_CHINESE-LASER-SYSTEM-NUMBER-513". That's not exactly the codes used in the real world but you get the idea. – slebetman Mar 17 '22 at 07:38