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Old 02-13-2012, 08:17 AM
66Scorpio 66Scorpio is offline
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Why canít we use lasers as ray guns?

I'm no scientist but I am ex-military and a sci-fi game designer. The problems with energy weapons are the amount of energy you need to generate, and the speed at which you release it.

A .22 caliber pistol has a typical muzzle energy of 159 joules and it delivers that energy in about 3/100,00ths of a second.

Your basic unit of work is the Watt and defined as one joule per second. Hold the phone: 159 divided by 3/100,000 is 5,300,000. You need better than a 5 megawatt laser to deliver the same punch as a puny .22! Even scaling down to a 10 millisecond pulse, you still need to generate 16 kilowatts to put the same amount of energy on target.

Lasers with this sort of power output are still vehicular mounted rather than something you could hip holster.
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  #2  
Old 02-13-2012, 10:16 AM
XT XT is online now
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Here's the article for anyone interested.

Yeah, until they have small, high output energy source that is both portable and has a quick recharge, ray guns and the like aren't going to be something you carry on your hip...or even on a backpack.

-XT
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Old 02-14-2012, 12:53 AM
Hagen Hagen is offline
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So, what I'm wondering is how long will I have to wait before energy density is enough to rival, say, a Glock. Isn't there something like Moore's law for energy? Or is there a limit for chemical energy? Can we miniaturize a nuclear reactor maybe?
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Old 02-14-2012, 11:53 AM
John W. Kennedy John W. Kennedy is offline
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We cannot miniaturize a fission reactor; fission simply doesn’t work until you have enough fissionable material gathered into a small space. There are all sorts of problems with natural-decay reactors, including shielding. And fission reactors require confinement, plus shielding.

I suppose there’s something like Moore’s law for energy, but it’s much slower. (In 1907, a Stanley Steamer was clocked at 197mph before it hit a bump and, the entire car serving as a lifting body, flew a hundred feet before it crashed.)
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Old 02-21-2012, 04:52 AM
enigmatic enigmatic is offline
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As I mentioned in the other thread, I wrote a whole article about this - LINK

The TLDR version is that any laser powerful enough to actually burn a hole in you, is going to be thousands of times over the level in which it can blind you just by reflecting off nearby (matte) surfaces.

Lasers are also poor at actually damaging stuff, compared to firearms, because heat tends to stay in one place, compared to kinetic energy, which has more drive and ambition

Lasers are good at putting a lot of energy in one place, though, and the power source issues aren't insurmountable. It's the blindness thing that makes laser pistols pretty much impossible.

It's hard to market a weapon that has a tendency to blind the wielder when fired at a target wearing a white t-shirt.

Last edited by enigmatic; 02-21-2012 at 04:53 AM..
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Old 02-21-2012, 05:55 AM
Mijin Mijin is offline
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Quote:
Originally Posted by enigmatic View Post
It's hard to market a weapon that has a tendency to blind the wielder when fired at a target wearing a white t-shirt.
Is that necessarily true? Surely there are EM frequencies which are damaging but will not reflect / cause photon emission to dangerous levels.
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Old 02-21-2012, 06:31 AM
enigmatic enigmatic is offline
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My understanding is that this is true over all of the frequency ranges that could reasonably feature in what we'd describe as a laser (the working definition of which is a little wooly). It's certainly true that invisible frequency light lasers actually tend to be more dangerous, as they won't trigger the blink reflex

There are going to be moderating factors, like you say, different reflection profiles will be an issue, I'm also pretty sure that there is a specific frequency range that is absorbed well by the fluid in your eyes, which does make lasers safer.

As I understand it, though, clever frequency selection is only going to buy you a few orders of magnitude worth of risk mitigation, and any halfway destructive laser is already so far over the optical danger zone that this just doesn't cut it.

I'm not a laser expert though.
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Old 02-23-2012, 08:26 AM
Hagen Hagen is offline
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I would venture that in this case laser applies to directed energy weapons. UV, microwave, IR; I'd consider all of these "lasers" if it comes in a nice handheld design, features a trigger and goes pew pew.

As for energy requirements, I realize that there are limits to batteries as an energy source, but it's hardly the end all of energy generation and storage. What about fuel cells, generators, etc? Surely there's some alternative.

Cheers
Luke
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Old 02-23-2012, 03:26 PM
John W. Kennedy John W. Kennedy is offline
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Generators don’t get energy from nowhere. For the figure posited above of 16 kilowatts, you’re talking 21 horsepower. That means you're carrying a rather large power mower on your back—not to mention the noise and pollution and heat. Fuel cell? Less noise and pollution and heat, but if it's hydrogen-fueled, you’re lugging a bomb around.
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  #10  
Old 03-01-2012, 12:11 PM
jawshoeaw jawshoeaw is offline
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lasers!

There are large scale lasers that can user the energy from a chemical reaction, i.e. explosive reaction - see "gas dynamic lasers". They fire in bursts, one shot per "explosion" or continuous with a gas/gasses fed in as fuel. Solves the problem of energy storage, since chemical fuels have high energy density.

Problem is still scaling down for portability. If only there was a way of packing small amounts of explosive chemicals in some sort of "cartridge".

That said, batteries and capacitors can be used for very powerful single shots from a laser beam. Considering a $40 toy laser can burn your hand almost instantly, a quasi-l , burn-a-hole-in-you laser is already available. They have as an advantage, almost perfect precision. A computer can track a very rapidly moving target and hit it with almost 100% guarantee, something no projectile can match (maybe hypervelocity projectiles come close). It is frustrating to see machine guns used in much sci-fi still, come on guys, guns, really? But then I was thinking, in space, bullets just keep on going, whereas lasers start to spread out over large distances. And bullets have a nasty habit of poking holes in things that you don't want any holes in, like spacesuits.

My personal theory for the star wars type "blasters" is that a small amount of metal would be heated to almost a vapor, then accelerated to very high speeds. That way you have a sort of hypervelocity projectile that carries punch AND heat. Plus it explains how you can see the beam flying through the air.
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Old 03-01-2012, 01:33 PM
John W. Kennedy John W. Kennedy is offline
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Human-built, space-approved small arms on “Babylon 5” shoot helium plasma.
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