The protocol only prohibits the use of weapons whose intended purpose is to blind people. If a laser is meant to be lethal and happens to blind you, that wouldn't violate the protocol.
> Article 3: Blinding as an incidental or collateral effect of the legitimate military employment of laser systems, including laser systems used against optical equipment, is not covered by the prohibition of this Protocol. [0]
Don't know how effective it would be, since it's not the primary goal of such system.
One of the simplest missiles of all, the TOW [1] costs almost $20k. A friend who is a former Marine says it was common to fire half a dozen in practice.
I've heard from people who work for military contractors that development is very expensive because everything is very inflexible and clamped down and there is so much paperwork.
I wonder if that price is due to low production and that the price would come down with mass production in war. Maybe not the case here but I always assume this is the case with expensive new weapons that are likely mostly r&d costs being spread across relatively few orders in peacetime.
Partly, but mass production in time of war simply isn't a thing in this day and age — hot wars between roughly-comparable adversaries (as opposed to the asymmetric conflicts such as counter-insurgency campaigns) are generally over in double-to-triple-digit hours, a couple of weeks at most.
So the policy of most developed nations' militaries is "come with whatever you've got" and don't plan on building more kit until it's over.
For example WWII started with months of "phoney war" where both sides moved onto a war footing, followed by a short violent blitzkrieg.
WWII is also shows powers capable of exercising restraint, even Hitler, conducting a war he was obviously losing, opted to not use chemical weapons. WWIII could be fought in a couple of hours or it could go on for years with neither side willing to press the biggest button.
An active radar set in the missile, guidance computer, actuators, with power source and antennas, all hardened enough to tolerate being on a rocket accelerating hard to Mach 2, plus the missile itself with an engine big enough to get it to ~80k ft, plus a warhead and proximity fuse. I have no problem believing that it costs $3 Million.
Plus Raytheon overheads and profit. Either of which might be a larger portion of the price than any one of those hardware items. I'm not saying this is necessarily bad, just that it's a cost component. I bet the DoD is not super cost-sensitive for amazing weapons systems that can protect large assets, but they drive a hard bargain on butter and toilet paper.
Is anyone at liberty to talk about overhead and profit margins for these kind of systems? I previously worked for a related business which precludes me from giving numbers.
The laser weapon might not have a per-shot profit margin. Though they can build that into the service contract...
Some of that, for sure. I'm not saying that Raytheon et al are angels or anything, but in their defense, most of the "overhead" is likely due to the hoops they have to jump through to do things the way that their customer wants them to be done.
I haven't worked with Government or their suppliers, but I have worked for a large company that did a lot of manufacturing of semi-exotic stuff, and their procurements demands were completely irrational. They didn't want to maintain an inventory of parts that were complex to manufacture, but required that they be available to purchase on short notice without any kind of contract or schedule, and were willing to pay any price to get that. So suppliers sprang up to hold these parts in inventory for them and supply them on-demand at vastly marked up prices, to cover their costs of maintaining the inventory. I'm not sure if any explicit corruption was involved in setting that up, but that's the kind of thing that tends to happen at large organizations.
Then again, even if there wasn't any explicit corruption when setting these things up, it tends to happen later on as suppliers get established and try to bend the customer into having even more bizzare procurement rules, so that no other company could possibly comply with them and take their business.
Given that you put "General" in quotes, I'm not sure which part you think is bullshit.
If it's the part about him saying it, here's the youtube video[0] of a 4-star general in the US Army (Gen. David Perkins) making that claim.
And he's not advocating for lasers (it's unrelated to this article), he's advocating for alternative options, and mentions cyber and something like "sema?".
As far as could the patriot hit it, I would think the hard part would be tracking it. No idea what the RCS looks like on a quadcopter vs., say, a stealthy cruise missile.
As far as threats for use in asymmetric warfare, we've seen cheap drones that are used for recon, and we've seen them used to drop ordnance.
Huh, thanks for the link to the talk. That wasn't in the original article so I could hardly believe they got that correct.
Still, I don't see how that's justifiable even if they can drop grenades. They won't be able to do it very effectively, and in fact if it's close enough to drop a grenade on troops you probably don't want to be detonating a Patriot missile in the same area.
Actually, I think his whole point was that it wasn't really justifiable, but it wasn't the US Army that did it (I am curious who it was). Totally agree about the proximity thing.
The Patriot is not a shoulder-fired missile. It is a heavy-duty anti-aircraft missile that weighs 1,500 lb. In fact, some versions can shoot down medium-range ballistic missiles.
It'll be an interesting development if somebody manages to put a real laser weapon like this in the field and it ends up being effective against vehicles and aircraft. Missiles are expensive and relatively slow; a laser weapon could potentially shoot down missiles and aircraft so fast as to be a game-changer.
There's been a lot of noise about whether aircraft carriers and other capital ships are viable at all in the face of high-speed anti-ship missiles. Intercepting them with CIWS and counter-missiles is dicey, but a good laser system could make anti-ship missiles useless.
On the other hand, you have to wonder if operating aircraft at all might become non-viable if your enemy has weapons like that. Speed might become much less important and stealth much more important.
Yeah... that's a lot of momentum to deal with, in a rail gun. Deflecting it would be hard, and disrupting it would tend to turn the slug into a co-moving cloud of superheated particles/plasma. I'm not sure that's hugely desirable either!
Well, that superheated cloud would probably disperse some, making it more susceptible to air resistance than the slug is. On the other hand, if you only liquefy it, and so you get hit with the same mass of liquid metal...
If you can launch 20, I can add another laser. Just in terms of economics, you aren't going to win that fight.
A rail gun: If I shoot a laser at a missile, I can detonate the warhead, or the propellant, or destroy the guidance system. If I fire it at a railgun projectile, I can vaporize the whole thing, or I can vaporize part of it and hope that it changes the course due to either ablation forces or changing the aerodynamics. That's harder. On the other hand, a railgun isn't really a precision weapon, either.
Look at the bright side -- we seem to be approaching a point where the expected outcome of any serious war is one of either (1) no human lives lost at all, because high-tech weapons blow each other up before they can actually hit anything living or (2) a few of those high-tech weapons make it through the defenses, efficiently destroying your civilization in a matter of a few minutes and constraining human suffering to that brief period. :)
Mechas will always remain SF. There's just so much that's impractical about them, where do you even begin. Balance is one issue: if you can make it fall over, you've killed it. Speed is another; anything that big will be extremely slow. Another issue is the ground pressure (weight divided by surface area of feet); they would destroy most surfaces (including all roads), and they would easily get stuck this way. Another issue is the huge amounts of fuel and frequent refueligs it would need. Another is the huge cost, which coupled with sluggishness and corresponding permanent proximity to the battlefront makes them a prime target for infiltration and sabotage.
Even something as comparatively small and practical as the Boston Dynamics robots have failed to gain traction; years after even being in actual service for testing with the military, LS3 has been literally shelved because it's just not useful.
One of the funniest battle mecha scenes is from Pacific Rim (which is chock-full of stupidity) where the one mecha is just a crappy missile delivery system. Once it's waded half way out to sea and spent its missiles in about two seconds, it's bloody useless. Why didn't they rather spend the cash on other, more sensible launch platforms that could deliver orders of magnitude more firepower using the same kind of missiles? Or why not just attack the alien things much further away from shore with torpedoes launched from fighter jets? Or why not just launch nuclear-tipped torpedoes down the portal hole? (Well, it would be a boring movie, that's why.)
> Intercepting them with CIWS and counter-missiles is dicey, but a good laser system could make anti-ship missiles useless.
Of course, such a good laser system could make the aircraft, missiles, and landing craft launched from aircraft carriers, assault ships, and major surface combatants useless, too, at which point the survivability of the ships themsleves is something of a moot point.
I don't think that current laser systems are anywhere near powerful enough to destroy a landing craft. I think that reason why lasers are potentially effective against aircraft and missiles is that they are intrinsically fragile and rely on speed to avoid getting hit. But a landing craft can afford to have some armor, and I don't think it takes much armor to stop a laser.
Hypersonic doesn't get you anything close to the speed of light. As long as the targeting electronics can handle the hypersonic speed of the target - and those electronics are not getting slower - hypersonic won't make much difference.
Presumably the amount of energy dumped into the target is a function of how long the laser dot is on it. You'd probably need the laser on a particular area of the target a little while to disable it.
If your target is ducking behind waves and goes from beyond the horizon to onto of you fast enough, that would be pretty good against a laser probably?
Also in a real shooting war there won't just be a one or two missiles launched against an aircraft carrier, but 10s at least or maybe over a hundred. Tom Clancy's book Red Storm Rising examined this scenario.
The advantage of laser weapons isn't that they're the best response to expensive, high-end threats (say, a big supersonic missile) - the advantage is that they're cheap and suitable for low-end threats, since you pay pennies per "shot".
A few days ago there was an article about a US ally shooting down a ~$200 drone with a ~$3M Patriot missile, which is a great trade for the attacker in that scenario (like a pawn for a rook). Even assuming that there's some kind of coating that makes a missile laser resistant by dramatically reducing absorptivity in the spectra of concern, it's bound to have tradeoffs- likely in the form of expense, weight, or increased vulnerability to sensors.
In the short term, while the technology is still pretty new, perhaps. But that would assume an agility on the part of the people building the targeted missiles that I'm pretty sure only players like Russia and China can offer, and we don't want to get into a shooting war with them, anyway. For most of the other states (or non-state actors) that we might be exchanging fire with, that's out of their reach, making this a potentially very cheap (relatively) and effective countermeasure.
Moreover, if battlefield lasers follow the growth-curve of most other technologies, they will quickly reach a point where, not only is adding power to the lasers easier than adding armor to the missiles, the amount of additional mass required becomes infeasible.
On the flip side, it seems that mirroring the surface of a missile or UAV would make it easier to detect, and therefore easier to target with "legacy" systems. I imagine both legacy and laser-based systems would be used in conjunction with each other.
You'd be right. It would need to dwell for considerable time on the same part of the tank's armor to have any meaningful effect, and even that would rely on slow, inefficient heating as a mechanism. (Assuming a rather improbable 100% kinetic energy transfer from a 60kW beam, that equates to about three .50 BMG rounds per second from contact range. That's a big round, but not big enough to have a significant effect on tank armor.)
To address another commenter's point, it would not set off explosive reactive armor (ERA). While I don't have detailed information on the ERA compositions in common use, the constraints at hand effectively necessitate the use of relatively insensitive plastic explosives, broadly similar in characteristics to the well-understood C4. Such explosives require a shock wave, provided by a special device or (in the case of ERA) by the impact of a shaped charge, to detonate; heat and fire will not set them off. (Vietnam-era American soldiers burned pieces of C4 from Claymore mine charges as cooking fuel. The smoke was toxic, but that was the only danger.)
You need a composition like this for ERA because it is not an actively controlled system. It's not as though there is a computer in the tank which detects an impact and detonates the corresponding ERA segments; the physical processes of such impacts play out far too quickly for such active control to work. ERA therefore has to work on a purely physical basis if it's going to work at all, and that means you need to use an explosive susceptible to detonation on impact. But you don't want an explosive that's very sensitive to impact, or to heat or fire, because you don't want to waste ERA or unnecessarily endanger infantry operating near the tank. (ERA's dangerous enough already that way without giving it a hair trigger!)
So it's already not all that plausible that a beam like this might transfer enough energy, even on direct impact with a mass of such explosive, to set it off. But the impact won't be direct, because ERA isn't constructed of bare explosive blocks; there's always going to be a layer of metal, not armor but still relatively thick, between the explosive and the outside environment. This structure would intervene between the explosive and the beam, and would dissipate the transfer energy as heat. That might eventually set the underlying explosive on fire, but, for the reasons we've already covered, it would not cause a detonation.
I'm really not getting your point on the context here. The actual effects of this on a real target will depend on a huge number of variables (I bet it's great against stealth things, but cheap drones will start using aluminum paint).
They do. That's exactly the point. Or, more specifically, if your laser is so strong that mirrors can't handle it, you can't also generate it because you need mirrors for that too.
It's just that you can't use them everywhere. It may be useful to ask where mirrors can viably go, and where they can't, but discussing the effects on mirrors won't lead anywhere.
If the mirroring is perfect, the photon transfers a bit of momentum as it reflects. If the mirroring isn't perfect, it has some probability of being absorbed, transferring half the momentum that it would if reflected, but transferring all its energy...
The rendering of the mounted laser system firing a massive, fuzzy red beam at an unspecified target is exactly how I remember it looked when I last saw it demonstrated...some thirty years ago.
From what I've read about these high intensity lasers in rain and fog they just 'burns a hole' though to the target. That absorbs energy but only for the initial start up. In a monsoon situation I would expect it to be useless though.
I wondered if they might make for a sort of 'fog plow' which would burn away the fog but the volume of air you would need to heat to keep a road cleared is rather huge.
Dust, and in particular volcanic ash (which is basically glass shards) are more of an issue. It raises the question of whether a missile could eject a powder to mitigate laser power landing on the missile.
Even in a monsoon I imagine a powerful enough laser should have no problem, no? Relative to the light of the laser, the rain drops are stationary. But maybe the power required to 'burn' through all that rain is higher than the discussed class of laser weapons.
Interestingly flying through volcanic ash, even in small amounts, is exceptionally hard on aircraft. So hard in fact that in one of the DARPA call for wild ideas rounds I suggested a "puffer ball" defense system consisting of a steam or air pressured dispenser on ship that could fire a 'plume' of volcanic ash to a height of up to 1000 meters. If any aircraft 'buzz' your ship with that plume up they are going to lose their engines. It could also make for a shore based cruise missile defense where you puff it infront of the missile and hope that the missile's radar can't see enough of it to jog left or right. It is remarkable stuff[1]
> How does this perform in adverse weather conditions?
One could ask the very same thing about WWI era aircraft. Look at where we are today.
Presumably there would other defense systems to fall back on during adverse weather. Even if this first-generation laser system worked well only on days where it wasn't raining, that would still represent an enormous cost savings.
Are there any physicists here who might be able to explain whether or not laser weapons would be effective underwater, e.g., mounted on a submarine for point defense against torpedos?
What about from LEO or from space? Would the atmospheric layers or other factors affect the operation of a laser weapon possibly fired from space to Earth?
(Most of us are curious about the possibility of sharks with lasers on their heads, but would be strongly discouraged from asking directly.)
> Are there any physicists here who might be able to explain whether or not laser weapons would be effective underwater, e.g., mounted on a submarine for point defense against torpedos?
Not a physicist, but as I understand the optimal wavelengths for underwater use would be substantially different than for use it atmosphere, and with similar output effective ranges will be much shorter, but there is no fundamental reason why you can't have underwater laser weapons.
> there is no fundamental reason why you can't have underwater laser weapons
Even at optimal wavelenghts and clean water, seawater absorbs/scatters light so much more strongly than air that underwater laser weapons are pretty much infeasible. The best wavelength is blue-green-ish, but even there you lose 5% intensity per meter (the loss is exponential in distance).
Water is also pretty good at muffling explosions. If you can take out torpedoes at 30 meters (80% of energy wasted, needs 5x more power), it might still be worth it as a point defence.
I'm not a physicist, an EE, but I saw a conference presentation on underwater LIDAR. Talking with the presenter, the silt is a real issue and severally limits beam quality and range. Sea water is pretty dirty.
No, not amortized. That's the variable cost only; it's not amortizing the fixed cost at all.
Think about a plane that fires missiles, for example. This would be saying that the missile costs $1 million. That's per missile. It's not saying that, after enough missiles, we also have paid for the plane.
Military lasers are getting close. The consensus has been that around 100KW, they start being effective weapons. This one is 60KW. The ship-mounted XN-1 LaWS, from 2014, is 30KW.
The US had a 2.2MW continuous laser, the MIRACL, in the 1980s, but it was a chemical laser that used large quantities of deuterium fluoride, was building-sized, and broke down frequently. The newer lasers are solid-state devices.
95 comments
[ 2.7 ms ] story [ 166 ms ] threadDon't know how effective it would be, since it's not the primary goal of such system.
[0] https://en.wikipedia.org/wiki/Protocol_on_Blinding_Laser_Wea...
I thought they were at most $50k a piece. This is unbelievable.
[1] https://en.wikipedia.org/wiki/BGM-71_TOW
So the policy of most developed nations' militaries is "come with whatever you've got" and don't plan on building more kit until it's over.
For example WWII started with months of "phoney war" where both sides moved onto a war footing, followed by a short violent blitzkrieg.
WWII is also shows powers capable of exercising restraint, even Hitler, conducting a war he was obviously losing, opted to not use chemical weapons. WWIII could be fought in a couple of hours or it could go on for years with neither side willing to press the biggest button.
(Source: http://www.fi-aeroweb.com/Defense/Patriot-PAC-3-MSE.html)
Is anyone at liberty to talk about overhead and profit margins for these kind of systems? I previously worked for a related business which precludes me from giving numbers.
The laser weapon might not have a per-shot profit margin. Though they can build that into the service contract...
I haven't worked with Government or their suppliers, but I have worked for a large company that did a lot of manufacturing of semi-exotic stuff, and their procurements demands were completely irrational. They didn't want to maintain an inventory of parts that were complex to manufacture, but required that they be available to purchase on short notice without any kind of contract or schedule, and were willing to pay any price to get that. So suppliers sprang up to hold these parts in inventory for them and supply them on-demand at vastly marked up prices, to cover their costs of maintaining the inventory. I'm not sure if any explicit corruption was involved in setting that up, but that's the kind of thing that tends to happen at large organizations.
Then again, even if there wasn't any explicit corruption when setting these things up, it tends to happen later on as suppliers get established and try to bend the customer into having even more bizzare procurement rules, so that no other company could possibly comply with them and take their business.
Sounds like this "General" was making an embellished hypothetical example of why this laser system is useful.
If it's the part about him saying it, here's the youtube video[0] of a 4-star general in the US Army (Gen. David Perkins) making that claim.
And he's not advocating for lasers (it's unrelated to this article), he's advocating for alternative options, and mentions cyber and something like "sema?".
As far as could the patriot hit it, I would think the hard part would be tracking it. No idea what the RCS looks like on a quadcopter vs., say, a stealthy cruise missile.
As far as threats for use in asymmetric warfare, we've seen cheap drones that are used for recon, and we've seen them used to drop ordnance.
0 - https://youtu.be/6v7nfB5bV3E?t=14m54s
Edit: here's a link to a picture of an ISIS-modified drone used to drop grenades: https://twitter.com/AlexMello02/status/819259288950624256/ph...
Still, I don't see how that's justifiable even if they can drop grenades. They won't be able to do it very effectively, and in fact if it's close enough to drop a grenade on troops you probably don't want to be detonating a Patriot missile in the same area.
https://en.wikipedia.org/wiki/MIM-104_Patriot
https://www.youtube.com/watch?v=HoT-h0S1gkE
https://www.youtube.com/watch?v=EkzxP-Wt9oo
The difference here is Lockheed knows why they're developing this technology, in Real Genius they were being tricked.
There's been a lot of noise about whether aircraft carriers and other capital ships are viable at all in the face of high-speed anti-ship missiles. Intercepting them with CIWS and counter-missiles is dicey, but a good laser system could make anti-ship missiles useless.
On the other hand, you have to wonder if operating aircraft at all might become non-viable if your enemy has weapons like that. Speed might become much less important and stealth much more important.
There are also things like rail guns, which might be harder to intercept with a laser.
You know, I think you'd just see a radical re-design in that case, you'd have to; like the Zumwalt, only more armored.
A rail gun: If I shoot a laser at a missile, I can detonate the warhead, or the propellant, or destroy the guidance system. If I fire it at a railgun projectile, I can vaporize the whole thing, or I can vaporize part of it and hope that it changes the course due to either ablation forces or changing the aerodynamics. That's harder. On the other hand, a railgun isn't really a precision weapon, either.
Yay F-35!
Even something as comparatively small and practical as the Boston Dynamics robots have failed to gain traction; years after even being in actual service for testing with the military, LS3 has been literally shelved because it's just not useful.
One of the funniest battle mecha scenes is from Pacific Rim (which is chock-full of stupidity) where the one mecha is just a crappy missile delivery system. Once it's waded half way out to sea and spent its missiles in about two seconds, it's bloody useless. Why didn't they rather spend the cash on other, more sensible launch platforms that could deliver orders of magnitude more firepower using the same kind of missiles? Or why not just attack the alien things much further away from shore with torpedoes launched from fighter jets? Or why not just launch nuclear-tipped torpedoes down the portal hole? (Well, it would be a boring movie, that's why.)
Of course, such a good laser system could make the aircraft, missiles, and landing craft launched from aircraft carriers, assault ships, and major surface combatants useless, too, at which point the survivability of the ships themsleves is something of a moot point.
If your target is ducking behind waves and goes from beyond the horizon to onto of you fast enough, that would be pretty good against a laser probably?
A few days ago there was an article about a US ally shooting down a ~$200 drone with a ~$3M Patriot missile, which is a great trade for the attacker in that scenario (like a pawn for a rook). Even assuming that there's some kind of coating that makes a missile laser resistant by dramatically reducing absorptivity in the spectra of concern, it's bound to have tradeoffs- likely in the form of expense, weight, or increased vulnerability to sensors.
Moreover, if battlefield lasers follow the growth-curve of most other technologies, they will quickly reach a point where, not only is adding power to the lasers easier than adding armor to the missiles, the amount of additional mass required becomes infeasible.
To address another commenter's point, it would not set off explosive reactive armor (ERA). While I don't have detailed information on the ERA compositions in common use, the constraints at hand effectively necessitate the use of relatively insensitive plastic explosives, broadly similar in characteristics to the well-understood C4. Such explosives require a shock wave, provided by a special device or (in the case of ERA) by the impact of a shaped charge, to detonate; heat and fire will not set them off. (Vietnam-era American soldiers burned pieces of C4 from Claymore mine charges as cooking fuel. The smoke was toxic, but that was the only danger.)
You need a composition like this for ERA because it is not an actively controlled system. It's not as though there is a computer in the tank which detects an impact and detonates the corresponding ERA segments; the physical processes of such impacts play out far too quickly for such active control to work. ERA therefore has to work on a purely physical basis if it's going to work at all, and that means you need to use an explosive susceptible to detonation on impact. But you don't want an explosive that's very sensitive to impact, or to heat or fire, because you don't want to waste ERA or unnecessarily endanger infantry operating near the tank. (ERA's dangerous enough already that way without giving it a hair trigger!)
So it's already not all that plausible that a beam like this might transfer enough energy, even on direct impact with a mass of such explosive, to set it off. But the impact won't be direct, because ERA isn't constructed of bare explosive blocks; there's always going to be a layer of metal, not armor but still relatively thick, between the explosive and the outside environment. This structure would intervene between the explosive and the beam, and would dissipate the transfer energy as heat. That might eventually set the underlying explosive on fire, but, for the reasons we've already covered, it would not cause a detonation.
I'm really not getting your point on the context here. The actual effects of this on a real target will depend on a huge number of variables (I bet it's great against stealth things, but cheap drones will start using aluminum paint).
> > > So, is now when everyone starts to put mirrors on their missiles, tanks, and aircraft?
> > ...
> It melts.
That's their point: mirrors don't magic away lasers. Dismissing this weapon with a simple "but mirrors!" is foolish.
They do. That's exactly the point. Or, more specifically, if your laser is so strong that mirrors can't handle it, you can't also generate it because you need mirrors for that too.
It's just that you can't use them everywhere. It may be useful to ask where mirrors can viably go, and where they can't, but discussing the effects on mirrors won't lead anywhere.
http://www.3djoes.com/cobra-maggot.html
I'm thinking dust storms, rain, and fog — anything that puts droplets/dirt in the beam path is going to scatter/absorb energy.
Which brings us back to the old staple of warfare, the smokescreen.
I wondered if they might make for a sort of 'fog plow' which would burn away the fog but the volume of air you would need to heat to keep a road cleared is rather huge.
Dust, and in particular volcanic ash (which is basically glass shards) are more of an issue. It raises the question of whether a missile could eject a powder to mitigate laser power landing on the missile.
[1] http://www3.alpa.org/portals/alpa/volcanicash/03_NASADC8AshD...
One could ask the very same thing about WWI era aircraft. Look at where we are today.
Presumably there would other defense systems to fall back on during adverse weather. Even if this first-generation laser system worked well only on days where it wasn't raining, that would still represent an enormous cost savings.
What about from LEO or from space? Would the atmospheric layers or other factors affect the operation of a laser weapon possibly fired from space to Earth?
(Most of us are curious about the possibility of sharks with lasers on their heads, but would be strongly discouraged from asking directly.)
https://www.paypal.com/donate/?token=M3PrHdnj1UclPkUsMMZgfvH...
Not a physicist, but as I understand the optimal wavelengths for underwater use would be substantially different than for use it atmosphere, and with similar output effective ranges will be much shorter, but there is no fundamental reason why you can't have underwater laser weapons.
Even at optimal wavelenghts and clean water, seawater absorbs/scatters light so much more strongly than air that underwater laser weapons are pretty much infeasible. The best wavelength is blue-green-ish, but even there you lose 5% intensity per meter (the loss is exponential in distance).
https://www.youtube.com/watch?v=TvPOWjF9nEM
Amortized over a few million shots.
Think about a plane that fires missiles, for example. This would be saying that the missile costs $1 million. That's per missile. It's not saying that, after enough missiles, we also have paid for the plane.
The US had a 2.2MW continuous laser, the MIRACL, in the 1980s, but it was a chemical laser that used large quantities of deuterium fluoride, was building-sized, and broke down frequently. The newer lasers are solid-state devices.
For instance, stick it on a drone and use it to weed a field from 1000 ft?