I've used the laser from a DVD burner and let me say that it doesn't burn much of anything!
I got several lasers from a couple of DVD burners and combined them with an adjustable focus lens that was specifically made for laser diodes. I then shot it at anything and everything. Here's what I can tell you about what burns and what doesn't:
Black Electrical Tape: You can burn a hole in this. It takes some time to get the laser focused right, but when it does you can burn very small holes. It's hard to actually "cut" the tape with the laser. It's more like making a series of very small holes than slicing a line through it.
White paper: Forget about it. The laser, even when well focused, just reflects off of this and does nothing.
Black paper: Will put small holes in it. By small, I mean something around 0.5 mm. Larger holes are difficult and needs to be made from a bunch of smaller holes.
Brown Paper (a.k.a. Cardboard): With time and effort it can make small holes. The holes only go through the first layer and not completely though the cardboard.
Plastic: Will make very small marks in black plastic. No holes. Does nothing to light colored plastic.
Balloons: Might pop a dark colored balloon. Nothing to a light colored balloon.
Matches: It can work, but it's hard. It doesn't work on white or red tipped matches. Darker colors, or matches marked with a black marker, will ignite.
So... It won't work for ping-pong balls. But it's still cool and worth making one to just play with.
Warning: You MUST use eye protection with this! Seriously. I speak from hard-earned experience. The laser, when reflecting off of brown cardboard, has enough energy to make your eyes hurt after 30 minutes of playing around. If you accidentally got hit directly in the eyes or got a reflection off of something shiny then you'd be in a world of hurt. At this wavelength and optical power, a simple pair of dark sunglasses is good enough in a pinch. Of course a real pair of laser goggles is preferred.
1) Is it really as simple as grabbing a laser drive chip and a
three-terminal diode from digikey and hooking them up according to the
datasheet? Should the laser drive chip be able to handle all
protection mechanisms necessary, or is there typically another device
that's needed to handle some other form of protection?
The laser drive chips I'm familiar with are more about applying rapid modulation to the laser than providing DC power. Usually there's an additional power circuit required; and that power circuit is where the protection is normally implemented.
If you have a different type of drive chip in mind, please link the datasheet in your question.
2) Is there a central regulatory body that does any testing to
determine what class of laser you have, and whether your product
follows all the necessary regulations?
In the US, it's up to the laser manufacturer to self-certify their product. You may be able to find a consultant to assist you with that process if you don't have the expertise.
3) Are there any known issues using lasers with 1mm core plastic
optical fiber? I know that POF has very different transmission windows
vs. glass fiber, and I know that one of these optimal windows is
650nm.
Would the beam stay narrow inside the fiber, or would it begin
to disperse?
The fiber is a waveguide, and the laser power will remain confined within the fiber core. It will attenuate (lose power over distance). There is also a process called dispersion which means different components of the laser power taking different amounts of time to traverse the fiber---but if you're not switching the signal quickly that's not likely to affect you.
Edit: A major difference between POF and glass fiber is that even in its transmission window, POF has much higher attenuation than glass. Attenuation in glass fiber is measured in tenths of dB per km. Attenuation in POF (last time I worked with it, several years ago) is measured in tenths or whole dB per meter.
Would it still be coherent and collimated after going through, say, 15 meters > of POF?
The signal will still be coherent, but the dispersion effect I mentioned above may reduce the coherence length if you've gone through a very long fiber.
The output beam will diverge at a substantial angle (not strictly collimated) when it exits the fiber. The divergence is a diffraction effect and the angle is inversely related to the fiber core diameter --- meaning POF will have a lower divergence angle than smaller-core fibers. In multi-mode fiber like POF the output divergence angle also depends on details of the fiber construction. In general the output divergence angle will be similar to the input acceptance angle.
I am investigating the laser approach, because it seems like most LEDs aren't even capable of 500 uW.
It doesn't matter much what most LEDs can do --- if you can find one LED that meets your needs, that is enough. And I think you should be able to find an LED to produce 1 mW and couple into POF, if you look long enough. But a laser should be able to do it more efficiently (but maybe more expensively).
Edit: Be aware that using an LED does not reduce your safety concerns. 1 mW is still 1 mW and can still be dangerous. You will want the same safety precautions (you mentioned open-fiber control) whether you use a laser or LED. Regulations have not all kept up with the improved capabilities of LEDs in recent years, but that doesn't mean you shouldn't protect yourself and your users.
Best Answer
First, just to pick nits, an LED is not a laser, and vice-versa.
That said, you might try eBay, searching for "laser module TTL", and you can get quite powerful lasers which can be digitally modulated, usually in excess of 10 kHz - that's why you need to specify TTL. Beware of the small cylindrical units - they typically cannot run for more than 60 seconds without overheating unless you provide extra heatsinking. And the bigger ones will have problems with eye safety, but you can get around that by defocussing them. However, you really need to start learning about the ins and outs of eye safety, since more or less by definition you're going to be pointing lasers at people's eyes. Nowadays folks tend to really freak out if they find themselves looking down the beam of a laser (the wussies).
While you're on eBay, consider finding very narrowband optical filters at the wavelength you're planning to use. When you're operating in the great outdoors, Mr. Sun is not your friend.
Putting a detector in an old headlight is a decent idea in principle, but the details of actually making a robust mount will be more of a challenge than you think. Plus, the better your system gets at concentrating your incoming light, the narrower its field of view and the more difficult aiming it gets. Maintaining alignment also gets iffier, too.
As an aiming guide, you might consider sending a constant stream of null data, as close to alternating ones and zeros as you can, and producing an audio output from the receiver. This will let you aim your system by listening to the tone, and such fast audio feedback will be enormously useful.
I'm not bringing this up to discourage you, just to let you know that you're in for a tussle.