RE: CDRH rules governing private laser shows.
I had been wondering about this very question, and a few others, for a long time, so in October, 2004 I took the drastic step of calling the CDRH in Maryland.
For a government agency, they were surprisingly helpful and forthright.
The bottom line is this: The CDRH has *NO* juristiction unless there is some form of commerce involved. So, as long as you do not charge admission to your show, you are free and clear as far as the FDA is concerned. (Note that you can still be sued in civil court by members of your audience if you zap someone, and you can also be prosecuted by the local police for reckless endangerment if you do something really stupid...)
The two people I spoke with over the course of a week or so were quite clear to point this commerce clause out to me. They also reminded me that "indirect" commerce can sometimes count as well. This is that grey area where you aren't directly charging for the show, but there is some other form of "compensation" going on in leu of pay. It also includes cases where a club owner installes a laser show and then starts charging a cover charge. While the laser show is "free" in the sense that once you are in the door, all the light show effects are "free", you still have to pay to get in the door, and the club owner is still engaging in laser-based commerce. (Though even here, there are exceptions... It's a strange world!)
After speaking frankly with these two gentlemen, I asked them both the specific question about doing free demonstration shows in a school. Both men agreed that the CDRH had no jurisdiction whatsoever in that case. The second man I spoke with did remind me that some schools, and most universities, will demand that you comply with the ANSI Z 136.5 standards for laser safety - assuming that the school knows what a laser is and that the standard exists, that is.
And finally, I encourage others to make the call to the CDRH... They really were helpful! I plan on calling them again once I start working on my whitelight projector...
Adam