DIY Laser Pistol Shoot 1MW Blasts

An anonymous reader writes "It doesn't get cooler than this — a German hacker put together a 1MW laser pistol capable of shooting straight through a razor blade with a single pulse. Quoting: 'Fitted with a Q-switched Nd:YAG laser, it fires off a 1 MW blast of infrared light once the capacitors have fully charged. The duration of the laser pulse is somewhere near 100ns, so he was unable to catch it on camera, but its effects are easily visible in whatever medium he has fired upon.'" Update: 03/17 18:22 GMT by T : Too bad; turns out it's "only" 1KW, rather than 1MW. I still want one.

Comments

Sweet

[Anonymous Coward]

Sweet. How long does it take to charge? IMMA FIRING MY LAZORS PEW PEW PEW

Re:Sweet

[halfEvilTech]

now the bigger question...

Did he add a sound modulator that makes the PEW sound every time he squeezes the trigger?

Re:Sweet

[gstoddart]

Did he add a sound modulator that makes the PEW sound every time he squeezes the trigger?

He likely didn't need to ... I suspect the squeals of glee followed by maniacal laughter suffice for the time being.

Wrong power

[MightyYar]

1kW, not 1MW.

Re:Wrong power

[conspirator57]

panda eats, shoulds, and leaves?

Re:Wrong power

[Leekle2ManE]

What he's saying is that at 1MW, it wouldn't shoot through just a razor, but probably through the wood behind the razor. And the bricks behind the wood. And the cinderblock wall behind the bricks. And the lead statue across the quad and the sign over the diner across the campus. Where he would stop for a burger.

Re:Wrong power

[Chris Burke]

Er, normally the power output is given as the power of the laser pulse, is it not? Rather than normalized to an equivalent laser that is on continuously. A 1 MW laser that is pulsed at 10 Hz with a 50% duty cycle would be outputting 1 MW during the pulses,and 0 otherwise, for a total of half the energy of a 1 MW continuous laser.

For example the laser in TFA, which is actually only 1 kW, pulses only once for 100ns. The actual power output of the pulse is 1 kW; it is not a 10 MW pulse that they average out over a second.

Re:Wrong power

[_0xd0ad]

http://en.wikipedia.org/wiki/Inverse-square_law

The inverse-square law generally applies when some force, energy, or other conserved quantity is radiated outward radially from a point source.

A laser does not act like a point source... or it does, but it acts like a point source which is very, very far away.

Re:Wrong power

[Anonymous Coward]

What the fuck is the matter with you guys??? He's got a cool, hand-held -laser gun- that shoots holes in stuff. Who gives a damn about "log10(4200), blah, blah, blah"

It's like a friend's just got laid by a Victoria's Secret model (this is for argument's sake, so shut up) and the discussion devolves into an argument about the velocity of the ejaculate.

Re:Wrong power

[_0xd0ad]

No. Re-focusing light creates a virtual image. Remember that from optics? It is the distance to that which the inverse square law follows, and that virtual image (in the case of a laser) is very, very far away. In a perfect laser, the distance to the virtual image would be infinite.

The inverse square law requires a point source. Suppose your laser has an aperture which is 1 mm in diameter. At 1000 m, the beam has expanded to a 2 mm diameter. By simple geometry you can infer that if a point-source of the light exists, it actually appears to be 1000 m behind the laser itself. Doubling the distance from the laser's aperture would only increase the distance from the virtual point-source by a factor of 1.5, not 2.

Re:Wrong power

[Salus Victus]

The problem here is that people aren't trained in physics. Watts are a measure of power, not energy. If you multiply the Power x the amount of Time, the result is the amount of Energy.

Think of it like a firehose vs. garden hose: the firehose pumps gallons of water per minute, but the garden hose takes a lot longer to pump the same amount of water. The "power" is like the size of the hose: how much energy does it pump in one second? That's like Watts. How much water ended up in the bucket? That depends on both Power and Time; you can fill the bucket faster with a firehose, but if you turn the firehose on and back off right away, then it's easy to get more water out of the garden hose by leaving it on longer. How much water ends up in the bucket is like how much Energy you used. 1 Joule is the amount of energy you get when you push 1 Watt for 1 Second. (1 Kilowatt-hour is the amount you get when you push 1,000 Watts for 1 Hour. If you're following the math, that means 1 KWH = 3,600,000 Joules.)

In a pulsed laser, each burst has a duration, and the most useful information is how much Energy is released per pulse (Joules). That's why they're measured by Energy (Joules or milliJoules). For a continuous laser, there is no "time" element, so the output is measured in Power (Watts).

So ... a 1 MW laser (Power) firing a pulse of 100ns (100 x 1/1,000,000,000th of a second), would give 1,000,000 Watts x 100 ns x 1 ns / 1,000,000,000 ns/sec = 100,000,000 / 1,000,000,000 = 100 / 1000 = 1/10th of 1 Joule each time it fires. A 60 Watt bulb uses 60 Watts per second ... 600 times as much Energy in 1 second as a 1MW laser delivers in 100ns. It's the incredibly small amount of time the pulse is firing (less than 1 millionth of a second) that results in so little energy being delivered to the target. It's the incredibly small area (focusing via the lens) that causes so little energy to do so much damage.

A 1 KJ (Kilojoule) laser would be delivering as much Energy in a single pulse (remember: if we're measuring the laser in Joules, we're giving the value per pulse) as a 1,000 Watt spotlight would use (mostly becoming heat) in 1 second.

I'm not saying this was made using a MW laser. I'm just explaining why a 1MW laser firing a millionth-of-a-second pulse isn't going to burn through anyone's bathroom wall. (And I'm not replying directly to Chris; I just wasn't sure where to drop this water-hose explanation into the conversation.)

Re:infrared? bogus.

[fuzzyfuzzyfungus]

It's a stormtrooper: you don't need to see the shots to know that the answer is "close enough to add drama; never close enough to kill an important character, despite these guys being the Empire's crack infantry forces..." In a universe ruled by narrative causality, ontology is an excellent substitute for empiricism...

Thievery

[Dan East]

A couple months ago I came a across a "game" at the mall, and I immediately thought "A person with a portable high powered laser could steal every bit of stuff out of this". Anyway the game is similar to those claw games, where you move the claw with a joystick to pick up an item. This game differs in that expensive items like DSi, PSP, iPod, are dangling from strings. The player moves an arm with an (obviously inept) pair of scissors on it, which tries to cut through the string to drop the item. It must take many cuts to gradually cut through the string, because I could see where strings had been slightly damaged by the cutters, but still needed a lot more to cut all the way through.

Anyway, a person with one of these lasers could clean house. The case is clear glass all the way around, so I assume the laser would shine right through it.

Sweet - of course Youtube to the rescue:
http://www.youtube.com/watch?v=BxeAi0v2DrI

Do not look at laser with remaining eye

[Z8]

This is cool and all, but I would be scared to go anywhere near that. That's way over class 3 on the laser safety scale and minor reflections could do permanent damage to your eyes. I've played with ~0.5W lasers, and those are scary enough. Apparently this is 1kW! The class 3 limit for pulsed lasers in that frequency is 1/3000th as much apparently (30mW). Basic safety goggles only filter out so much light and you can still get blinded through them.

I would guess it's just a matter of time before whoever bought this accidentally hits something shiny and the "ricochet" blinds someone.

Wrong unit

[slim]

It's not all that interesting what the power is, without knowing how long it's applied for. TFA says 100ns.

1kW * 100ns = 0.0001 joules
1MW * 100ns = 0.1 joules

Neither of which is very much energy. Next question: how small an area is that energy applied to? Pretty damned small, I'm assuming, if it's going to punch a hole in a razor blade with that little energy.

It doesn't seem to add up, though

[Kupfernigk]

1MW for 100ns = 0.1J, roughly equivalent to dropping 100g a distance of 10cm. 1kW for 100ns = 0.1mJ, equivalent to dropping a 1 gramme mass approx. 1mm. I believe the latter could pop a balloon, but it doesn't seem enough to punch through a razor blade. My memory may be faulty, but I seem to recall it takes of the order of magnitude of 10^10 W/sq cm to do that. Focussing the beam to 10^-7 sq. cm would be quite an achievement.

Perhaps either the original estimate is correct or the pulse duration is much longer, of the order of 100 microseconds.

Re:HAN PUNCHED FIRST!

[gstoddart]

It's actually spelled Snookiee. A lot of people make that error.

Not sure which is more sad ... the fact that you know that, or that you think we care. ;-)

Re:Total energy

[slim]

That's about the same amount of energy as lifting a 100 g
chocolate bar 10 cm vertically in the air....

... focussed on a tiny point -- it doesn't say how tiny.

Imagine attaching a needle to that 100g chocolate bar, then dropping it point-first at your hand, from a 10cm height.

Re:infrared? bogus.

[stjobe]

Stormtroopers are excellent marksmen - what you see depicted in those Rebel propaganda videos is a tactic called "herding". Funnily enough the makers of the propaganda videos never show what happens after the stormtroopers have herded the scruffy nerf-herder rebels into their trap...

Re:Awesome! and effective

[swb]

Part of the reason stopping power is such a big deal is that it takes a lot of energy to punch through rib cages and skulls. Most people who die from handgun wounds do so from exsanguination, not disablement of vital organs, and most of these people are shot with cartridges an order of magnitude more powerful than .22 long rifle.

I suspect that any energy weapon that wants to match a handgun in terms of energy delivered in the same time domain will need to produce at least as much energy to do the damage necessary, or operate on principals similar to a Taser and act on the nervous system.

Yeah, but...

[stink_eye]

Can I get a phased plasma rifle in a forty watt range?

Re:Talk about cool

[Local ID10T]

30797 fatal crashes occurred in the United States in 2009. Do you really want to add the risk of falling out of the sky to that?

Yes. More so if I can shoot them out of the sky with my laser pistol :)

Re:Awesome!

[Card]

From Wikipedia:

Infrared lasers are particularly hazardous, since the body's protective "blink reflex" response is triggered only by visible light. For example, some people exposed to high power Nd:YAG laser emitting invisible 1064 nm radiation, may not feel pain or notice immediate damage to their eyesight. A pop or click noise emanating from the eyeball may be the only indication that retinal damage has occurred i.e. the retina was heated to over 100 C resulting in localized explosive boiling accompanied by the immediate creation of a permanent blind spot.

Re:infrared? bogus.

[Lost Race]

In a universe ruled by narrative causality, ontology is an excellent substitute for empiricism...

That's exactly what I always say!

In a universe ... ruled by narrative causality ... one man ...