Saturday, April 23, 2011

Parts and preperation

Next project on the docket: Building a laser gun

First things first: lasers are not particularly effective for destroying things. They deliver heat. A large burning and cutting laser with a price tag in the tens of thousands might be a 50W laser. That means it's delivering 50 J/s. So if you hold it on target for 1 second, that target will receive 50J of energy. By contrast, an AK-47 bullet will deliver about 2000J to the target. Those can be had for about $300, weigh a lot less and don't need to plug into the wall. Thats why we don't use lasers for war: They're overpriced, weak, hard to port about, and generally a waste of money that could be spent on real guns.

So why build one? For starters, they're bad ass. Also, they're quiet, more socially acceptable to carry, and actually useful at times. I probably wouldn't start a camp fire with an AK. I would with a laser pistol.

That begs the question, what about all those costs? Well, the internet has already solved that. The goal of a laser is just to have a single wavelength of light. With one wavelength, it's possible to control and direct the beam in a way that multi-spectrum light can't. Multi-spectrum lite through lenses will disperse and it becomes difficult to control (this is what prisms do, except on purpose). By contrast, if you can make light of all the same wavelength going in some well known and regular direction, you can focus it to go just exactly where you want. For instance in a single straight column.

I gather there are really two ways to handle this. One way is to have a separate lasing material which you shine initiating light into and then pump. This is the shitty, expensive way. But it get you to higher power. The other way is to have a laser diode produce that light. It is difficult to get such diodes to high power (probably due to heat, but I'll admit I don't know).

I do know that Casio, the electronics company, developed a way to get them up to about 1W. And then they put 24 of em in a projector (a rather nice project, actually). These are the lasers that the Wicked Lasers people are harvesting. Except that Wicked Lasers is charging $300 for a single laser while the projectors are only $800. So I bought a projector.

It turns out the projectors even comes with a bunch of really convenient columnizing optics (though I've yet to run it independently, that's what it appears to be).

I only started ripping it apart, however, when my laser protection arrived.

Let me tell you, Thor Labs is a funky company. You buy $150, fuckin class-a laser goggles... and they send you some complimentary snacks. I can only assume these are meant for the starving grad students spending university money and eating out of vending machines.

To Thor Lab's credit, the snacks were both tasty and healthy.

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