# Solid State Lasers



## RobynC (Jun 10, 2011)

This is pretty straight forward: How much damage would a 15kw, 50kw, 90kw and 150kw laser do a house, an aircraft, and a human being?


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## tanstaafl28 (Sep 10, 2012)

RobynC said:


> This is pretty straight forward: How much damage would a 15kw, 50kw, 90kw and 150kw laser do a house, an aircraft, and a human being?


Burn a hole through it, depending on how close the laser is to the target.


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## Scrabbletray (Apr 27, 2014)

Well, obviously the big question is how often these lasers fire for? Most lasers generate a lot of energy for a short period of time. Obviously, a watt is a joule per second so every second these lasers are putting out 15,000J-150,000J of energy. I guess a good way of looking at the amount of energy is seeing how much water you could boil per second with each laser. Assuming the water is at 25C you have to heat it by 75C + boil it. That would be (75*4.184)+2260=2573.8 J/g, so these lasers could boil 5.8g, 19.4g, 35g and 58g of water per second respectively. That might not sound like a lot, but water takes a LOT of energy to boil. An easier metric for people to understand might be to compare it to other military hardware. 

Wikipedia lists the following muzzle energies for different sized military rounds:

pistol	9 mm 519J
pistol	.45 ACP 564J
rifle	5.56 × 45 mm 1,796J
rifle	7.62 × 39 mm 2,070J
heavy	.50 BMG 15,037J

So, for example, looking at a 7.62mm round like what an AK-47 fires shows that a 15,000kW laser is putting out energy at a rate of 7.5 AK-47 rounds a second and a 150,000kW laser is equivalent to 75 AK-47 rounds a second. In terms of heavy machine gun rounds a laser of these sizes would put out the equivalent of between 1 and 10 rounds per second depending on its size. Of course, keep in mind that this is the difference between kinetic energy and heat energy and so its effect on different targets would be far different. Shooting stuff with bullets obviously breaks stuff into pieces whereas shooting a laser at it is more likely to start a fire or cause severe burns or even total destruction of tissues on humans. I'd say a laser that can project this sort of energy at a distance for an extended period of time could do similar damage to a vehicle mounted machine gun, but is obviously far less than what could be achieved with tanks, planes, helicopters etc. It would be a very powerful infantry weapon, but a very weak weapon for a plane except for certain uses (like setting shit on fire).


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## Vaan (Dec 19, 2010)

There already is a solid state laser in use in the US navy. If you look on YouTube you will see it destroying a drone.

The biggest issue for lasers is cooling. Because it has to build up the energy it needs immense cooling to ensure it doesn't destroy itself doing so.


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## Zombie Devil Duckie (Apr 11, 2012)

RobynC said:


> This is pretty straight forward: How much damage would a 15kw, 50kw, 90kw and 150kw laser do a house, an aircraft, and a human being?




Coming up next on "*Will it burn*", we set a Kim Kardashian on fire from 1 mile away.


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## tanstaafl28 (Sep 10, 2012)

Vaan said:


> There already is a solid state laser in use in the US navy. If you look on YouTube you will see it destroying a drone.
> 
> The biggest issue for lasers is cooling. Because it has to build up the energy it needs immense cooling to ensure it doesn't destroy itself doing so.


Who needs lasers when they have rail guns?


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## Vaan (Dec 19, 2010)

tanstaafl28 said:


> Who needs lasers when they have rail guns?


Indeed, I much prefer the rail gun to lasers, our tech levels need to increase before lasers become a useful weapon.


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## tanstaafl28 (Sep 10, 2012)

Vaan said:


> Indeed, I much prefer the rail gun to lasers, our tech levels need to increase before lasers become a useful weapon.


The projectile requires no explosive content; the _velocity at impact_ provides all the required force, however, the EM charge required to fire the projectile is still a slight problem. 

There is talk that the new Zumault class destroyer may eventually be fitted with a railgun. It will be able to be fired at a range of 110 nautical miles (126 mi/203km) at speeds between mach 5-7.5. Sea trials are said to begin soon. If successful, it will replace far more expensive and slower cruise missiles as the most economic means of reaching out and killing targets.


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## tanstaafl28 (Sep 10, 2012)

@RobynC

Sorry for the sideline into railguns, here's some interesting info on the kinds of lasers you were talking about. 

Military Lasers


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## tanstaafl28 (Sep 10, 2012)

This is apparently the most powerful laser in the world, currently. 500 Terawatts:


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## RobynC (Jun 10, 2011)

How much power would you need to incinerate somebody?


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## tanstaafl28 (Sep 10, 2012)

RobynC said:


> How much power would you need to incinerate somebody?


Not a problem of power, but a problem of beam width. Like a big magnifying glass intensifying the power of the sun. I don't think a small bore laser will do the trick no matter how powerful, it will just burn a hole in a person, cauterizing the wound. It would not continue to burn outside the the radius of the beam.


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## Scrabbletray (Apr 27, 2014)

Also, incinerating someone would be a huge waste of energy. All you have to do is burn a hole through their heart or brain and they're dead, why go to all the extra effort to try and reduce them to ashes?


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## RobynC (Jun 10, 2011)

@a1b2c3d4

Well I could have told you that...


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## LibertyPrime (Dec 17, 2010)

@RobynC






It looks like it can vaporize a man, take down small aircraft, boats and land vehicles. It would probably light a house on fire instantaneously.



a1b2c3d4 said:


> Also, incinerating someone would be a huge waste of energy. All you have to do is burn a hole through their heart or brain and they're dead, why go to all the extra effort to try and reduce them to ashes?


..that kind of depends. You'd still be running on adrenalin even if the heart got hit long enough to shoot them in the head. People don't die instantly, for example a pipe the diameter of you thumb could shoot through your brain and if you are lucky you'd survive till old age or a few more painful years .

To kill someone with a sword instantly you'd have to slice their head off their shoulders, otherwise they'd survive long enough even with a claymore through their chest to kill you as well ^^;...

Real life is not the movies where people die exactly when the bullet hits them and they'd be so pumped on adrenalin that they probably won't notice the pain right away.


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## Scrabbletray (Apr 27, 2014)

FreeBeer said:


> @RobynC
> ..that kind of depends. You'd still be running on adrenalin even if the heart got hit long enough to shoot them in the head. People don't die instantly, for example a pipe the diameter of you thumb could shoot through your brain and if you are lucky you'd survive till old age or a few more painful years .
> 
> To kill someone with a sword instantly you'd have to slice their head off their shoulders, otherwise they'd survive long enough even with a claymore through their chest to kill you as well ^^;...


I think you're giving way to much credit to the ability of adrenaline to keep a person going after sustaining a mortal wound. I know there have been people to have significant brain trauma and survive, but that is a one in a million scenario. If the trauma is to your motor cortex you literally will drop like a rock. Other places would be just as bad, even if you survived a few seconds if the part of your brain that controls your ability to see, or think has been damaged your useless anyways. A hole through the heart is more or less the same way. Even though it may technically take a minute or two before brain cells start dying you are going to go into shock almost instantly. You might not be dead, but you're sure as hell not going to be shooting back either. It's kind of funny you mentioned decapitation though since when they used to guillotine people sometimes doctors would see how long the brains of the victims were still working and I've heard of studies where the severed heads could continue to make conscious decisions (like being told to blink one eye or another) for 30 seconds after decapitation had been performed. At any rate, in the course of a war whether someone dies instantly or after 30 seconds has very little impact. The probability that their last dying shot is going to hit someone seems pretty remote.


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## HAL (May 10, 2014)

a1b2c3d4 said:


> I think you're giving way to much credit to the ability of adrenaline to keep a person going after sustaining a mortal wound. I know there have been people to have significant brain trauma and survive, but that is a one in a million scenario. If the trauma is to your motor cortex you literally will drop like a rock. Other places would be just as bad, even if you survived a few seconds if the part of your brain that controls your ability to see, or think has been damaged your useless anyways. A hole through the heart is more or less the same way. Even though it may technically take a minute or two before brain cells start dying you are going to go into shock almost instantly. You might not be dead, but you're sure as hell not going to be shooting back either. It's kind of funny you mentioned decapitation though since when they used to guillotine people sometimes doctors would see how long the brains of the victims were still working and I've heard of studies where the severed heads could continue to make conscious decisions (like being told to blink one eye or another) for 30 seconds after decapitation had been performed. At any rate, in the course of a war whether someone dies instantly or after 30 seconds has very little impact. The probability that their last dying shot is going to hit someone seems pretty remote.


I think it depends on whether the person is aware their wound is mortal or not. Pain and shock manifests itself in funny ways.

If you can see a massive hole in your chest it might make your body go into shock shut down into last-ditch survival mode, with you going limp and lifeless or comatose.

However, I can give an example of a certain British police officer who was stabbed in the heart by a huge screwdriver. She thought the criminal had just punched her so she just carried on chasing him until she collapsed. She survived but only thanks to a very good and quick-thinking surgeon. So her ability to carry on was most likely due to the fact that she hadn't undergone the psychological trauma of knowing what had happened to her.

In general I think many things are not painful or shocking at all until you're aware of them. So maybe a person could do a lot more after receiving a mortal wound.


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## RobynC (Jun 10, 2011)

I know these questions sound pretty anti-social to ask, regardless I'm wondering how long before they'll somehow figure out how to justify using these things domestically


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## Death Persuades (Feb 17, 2012)

Google is your friend, dudette.


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## RobynC (Jun 10, 2011)

What are you talking about?


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