Smokescreen versus Lasers

[Serafina]

Simple question:

How would smokescreens affect weapon-grade lasers?
"Weapon-grade laser" as in "able to damage modern-day tanks" at least
and "smokescreen" as in "some kind of smoke/fog-forming substance"

Another intersting question is how one could devise the smokescreen to be better at interfering with lasers, say by putting larger particles in it (say, glass-dust or something like that).
Would such a smokescreen be able to block, or at least disperse lasers that could otherwise blow up a tank?

Regards
Fina

[Norade]

I would see no reason why it wouldn't work. I mean half the challenge with lasers is that normal air breaks them up and scatters them. As for glass shards, that could work, but if you're going that far maybe make them into tiny prisms to totally mess with the beam.

[Sea Skimmer]

If a laser is powerful enough to pierce the armor on a tank then it’s probably going to burn through a normal smokescreen . Laser rangefinders can already defeat smoke to a modest extent, and they have power levels in the low double digit watts. However the details would depend entirely on the depth and density of the screen, as well as how fast the smoke if is moving (this keeps pushing more smoke into the beam) and most importantly what kind of smoke it is. Not all smoke is equal. Anti thermal smoke for example relies on burning rubber particles actually being lofted into the air, creating a very hot cloud which doesn’t cool rapidly as it rises. You wouldn’t get the same effects from smoke from a giant burning pile of wet wood even if both block the naked eye equally well.

When laser weapons become commonplace it is like that specialist anti laser smokes would be developed, probably relying on lofting some kind of very reflective, very high melting point particular matter (dust in other words) into the air. Howeffective this could be, I don’t know.

[Norseman]

When laser weapons become commonplace it is like that specialist anti laser smokes would be developed, probably relying on lofting some kind of very reflective, very high melting point particular matter (dust in other words) into the air. Howeffective this could be, I don’t know.

Such things have already been theorized in many places, can't be good for your lungs though.

[open_sketchbook]

Eh, stay in your tank/power armour then. If your armour happens to be compromised, well, sucks for you, chump, should have put more points into your luck stat.

[Gil Hamilton]

When laser weapons become commonplace it is like that specialist anti laser smokes would be developed, probably relying on lofting some kind of very reflective, very high melting point particular matter (dust in other words) into the air. Howeffective this could be, I don’t know.

I imagine you can be even more specialized than that in a world of commonplace laser weapons. If the lasers aren't readily tunable for different wavelengths (quite possible, lasers often are the results of pumped electronic transitions, after all), you can inject into your dust bomb various kind of particles that have strong absorbance bands in those regions. Unless it was a really diffuse cloud of marginal path length, that would wreck the effectiveness of a laser, in addition causing rampant fluorescence that would make the clouds even harder to see through.

Of course, about five minutes later there will be protestors out because your anti-laser gas cloud mortals are giving people various kinds of metal poisoning, killing the crops of the natives, et cetera, but I'm certain that military-industrial complex folks won't let that disturb their sleep.

[Sea Skimmer]

Luckily for the military-industrial complex those kinds of people spend political capital and media airtime faster then they acquire it. Dense inert mental explosives for example have become relatively common in the last couple years, especially in Israeli use, and are basically certain to give the wounded cancer, and yet you hardly ever hear a word about them in mass media. That’s despite several campaigns to have them banned. The fools spent all the creds they getting anti personal mines banned.

Course this is also why you see TV adds for Lockheed Martin ect... all the time, even though they basically don’t build anything the average consumer can directly buy. The ad money flows to the media, the media shuts the fuck up because in the end they only care about entertainment programing disguised as new reporting to make money.

[TheMuffinKing]

Depending on the time-frame and power of the laser, I could see desert battlefields providing a natural screen that inhibits laser use.

[Darth Wong]

There may be some passive defenses against lasers. If we're talking about shooting lasers at targets such as ground vehicles, you might develop some kind of applique armour which naturally throws up a lot of thick blocking vapour when hit by a laser. That would be easier than deploying smoke canisters.

[Stuart]

Anti-laser smoke screen generators already exist and are in service. They're of no use in protecting missiles or aircraft but work very well in protecting tanks and ships. How they work is classified.

The applique armor idea is interesting.

[Serafina]

Remember, we are talking about weapon-grade lasers here, not about targeting or rangefinder ones.

And isnn't the applique armor idea an working prinicple of ablative armor anyway? Or did i misunderstand something here?

[Darth Wong]

Remember, we are talking about weapon-grade lasers here, not about targeting or rangefinder ones.

And isnn't the applique armor idea an working prinicple of ablative armor anyway? Or did i misunderstand something here?

The idea is that you can bolt on something specially formulated to grant maximum protection against lasers, without altering the basic armour composition and performance against projectiles (and without having to redesign existing vehicles).

[Terralthra]

I would see no reason why it wouldn't work. I mean half the challenge with lasers is that normal air breaks them up and scatters them. As for glass shards, that could work, but if you're going that far maybe make them into tiny prisms to totally mess with the beam.

Prisms work by splitting light into its composite wavelengths. Lasers generally only have 1 wavelength of light, so all a prism would do is bend the beam by the index of refraction of the material. Dust and the other things discussed herein are better ideas, cost-efficiency wise.

[Sea Skimmer]

Special applique armor would be useful, but its never going to be able to protect the entire vehicle. It just can’t. Against conventional anti tank weapons this is an accepted limitation, because even guided missiles aren’t accurate enough to do much in terms of targeting very specific parts of a tank. A laser however could be targeted on a gun barrel or a track or the commanders cupola. This could allow a tank or other AFV to be crippled as a fighting unit without any need for the firepower to melt through the main armor. A smoke screen some distance from the vehicle would prelude such precision targeting.

Another option, more useful in static situations then mobile ones, is a water spray curtain. The Sweds have used them for a long time to defend coastal batteries. This has the advantage that unlike a smoke screen you don’t have a plum drifting 100 meters in the air giving away your position for all to see.

[Serafina]

Special applique armor would be useful, but its never going to be able to protect the entire vehicle. It just can’t. Against conventional anti tank weapons this is an accepted limitation, because even guided missiles aren’t accurate enough to do much in terms of targeting very specific parts of a tank. A laser however could be targeted on a gun barrel or a track or the commanders cupola. This could allow a tank or other AFV to be crippled as a fighting unit without any need for the firepower to melt through the main armor. A smoke screen some distance from the vehicle would prelude such precision targeting.

Another option, more useful in static situations then mobile ones, is a water spray curtain. The Sweds have used them for a long time to defend coastal batteries. This has the advantage that unlike a smoke screen you don’t have a plum drifting 100 meters in the air giving away your position for all to see.

Does water work against lasers that are strong enough to melt armor, tough?

Really, i don't have the physics-knowledge to know wether it does or doesn't - thats why i am asking, after all.

Of course, even a reduction if firepower by 10-20% may be well worth it. So you don't have an "all or nothing" game.

[Gil Hamilton]

Does water work against lasers that are strong enough to melt armor, tough?

Really, i don't have the physics-knowledge to know wether it does or doesn't - thats why i am asking, after all.

Of course, even a reduction if firepower by 10-20% may be well worth it. So you don't have an "all or nothing" game.

Yes, atually. What it does is that when a water droplet interacts wth the laser beam, the water droplet is immediately vaporized and turns into basically spherical ball of steam. The ball of steam acts as a lens, which disperses the beam. How much the beam is dispersed is a function of the pathlength and density, but such a thing can degrade the performance of a laser rapidly.

The trick is to fire two discharges through the same path. The first discharge vaporizes all the water into gas and a bit of a second later, when the optical path is somewhat more evenly vaporized and you don't have less lensing effects, you fire the full power pulse through.

Water vapor is defeatable, but for a place like the coast of Sweden, it's basically free and it makes a hypothetical laser attack need a bit more oomph to it than turning the beam on the target, burning a hole in it, and moving to the next target.

[Darth Wong]

Special applique armor would be useful, but its never going to be able to protect the entire vehicle. It just can’t. Against conventional anti tank weapons this is an accepted limitation, because even guided missiles aren’t accurate enough to do much in terms of targeting very specific parts of a tank. A laser however could be targeted on a gun barrel or a track or the commanders cupola. This could allow a tank or other AFV to be crippled as a fighting unit without any need for the firepower to melt through the main armor. A smoke screen some distance from the vehicle would prelude such precision targeting.

That's a good point, although there's no rule that the applique armour has to be rigid. If it's some kind of flexible material, it could be more of a curtain-like structure, and it could get a lot closer to the ground (and be made into funkier shapes to conform to the outside of the tank) without causing a problem.

Another option, more useful in static situations then mobile ones, is a water spray curtain. The Sweds have used them for a long time to defend coastal batteries. This has the advantage that unlike a smoke screen you don’t have a plum drifting 100 meters in the air giving away your position for all to see.

How well would that work for a vehicle? Does it use up water quickly enough that the vehicle would need a huge water reservoir to make it last for any duration?

[Sea Skimmer]

How much water you’d need would depend on how powerful the laser is, since you’ve got to spray it up as fast as it can be vaporized. It might not work well for moving vehicles, but an awful lot of military equipment and installations are relatively static or don’t move often. In those cases being able to draw on local water supplies at least some of the time could be useful. For fixed positions it could also be realistic to sustain a water curtain 24/7 while you probably would not want to keep smoke going all the time even if you have unlimited fuel to do so. Since lasers would basically give no warning to even duck for cover surprise attacks are going to be a serious problem.

[Gil Hamilton]

How much water you’d need would depend on how powerful the laser is, since you’ve got to spray it up as fast as it can be vaporized. It might not work well for moving vehicles, but an awful lot of military equipment and installations are relatively static or don’t move often. In those cases being able to draw on local water supplies at least some of the time could be useful. For fixed positions it could also be realistic to sustain a water curtain 24/7 while you probably would not want to keep smoke going all the time even if you have unlimited fuel to do so. Since lasers would basically give no warning to even duck for cover surprise attacks are going to be a serious problem.

Water screens are great for coastal installations where water is basically free, but in alot of places, like in a desert, you aren't going to want to shoot large amounts of pressurized water into the air. The water spray method is just as dependant on the velocity of the spray as much as anything to attenuate the beam and one can imagine one of the conflict areas in the future will be places where people are fighting over water as a scarce resource.

[[R_H]]

Instead of using a laser as the primary weapon, what about using it as a secondary weapon and targetting optics and other vunerable bits, like Sea Skimmer said?

[Gil Hamilton]

Because I think we are thought exercising lasers as a primary weapon. The basic technology exists, though it painfully unmature. Like the MTHEL laser system that exists for shooting down missiles and even mortars and artillery exists... however, while the M stands for "Mobile" it still requires a couple semi trailers of equipment to operate and also the deuterium needed for it isn't exactly the cheapest material (you cannot substitute hydrogen for the reaction)*. It works, the Israelis were nailing mortars with it in tests, to say nothing about Katyusha rockets bulleyes. In the future, with the refinement of the technology**, there isn't a reason why we shouldn't see lasers-as-death-ray weapons on the field.

*I imagine though if we get cheap nuclear fusion at some point in the future as well, we can invent an efficient pathway for synthesizing deuterium directly and not have to worry about natural abundance issues.

**And let's face it, weapons developers suffer from the "Let's make something AWESOME and sell it to the government" itch more than most people. If they possibly can engineer some War of the Worlds Death Ray Shit, they will try. Funnily enough, MTHEL, the laser I mentioned above, is an infrared laser... sounds like something that a 19th century man would describe as a Heat Ray?

[Serafina]

Either way, it is about stopping them, not directly about their usage as weapons.

So far, i have seen quite convincing arguments that a smokecreen of some sort should work, at least to a certain extent.
Water may be a nice substitute, but suffers from obvious logistical problems (rarity in some region, huge volume).

[Sea Skimmer]

Instead of using a laser as the primary weapon, what about using it as a secondary weapon and targetting optics and other vunerable bits, like Sea Skimmer said?

Weapons like that have been around for a while decades now. The US Army fielded a couple anti optics laser units, mounted on the Bradley Stingray during the Gulf War for one example. However most work in the west has been held back because laser blinding weapons are illegal, and most politicians don’t want to here about the different between something meant to burn up and eyeball and something meant to ruin optics. We could use all the laser rangefinders on tanks and missile launchers as blinding weapons already if we wanted too, making the arguments against rather stupid. But when you look at the utter lack of logic involved in banning specific types of weapons, well it’s no surprise.

[Sarevok]

But is not aiming a laser at an enemy soldiers eyes difficult at useful ranges ?

[Gil Hamilton]

You just need to wave it in their faces, really. Retinas are reasonably easy to fry even with my 532nm laser pointer. An incidental exposure should be enough to put them out of action with messed up eyeballs.

Skimmer, you'd know better than I, are lasers meant for actually killing people directly still something that weapons researchers are pursuing? Cause I'd find it interesting if weapons meant to blind people with light were illegal, but weapons meant to cause small bits of people to explode in steam clouds are kosher.