If you embark on your own, remember: It's all fun hacking until your 18 sided mirror sticks and you dump that laser beam into a single spot and burn a blind spot on someone's retina.
Make half the fun be the redundant safety systems.
You need to spread enough photons per second across the entire area of the image to make it bright enough to see and look good. This translates into a fairly good bit of light.
As a thought exercise, consider a ridiculously bright 3 watt LED flashlight. Shine it through a 35mm slide to make a miniature projector. You now have enough photons to make something like a 3 foot image. You are going to need about 3 watts of laser to do the same job (no free lunch, except for green of course). A 1 watt laser is more than 10 times the power needed to instantly burn a permanent hole in your retina.
I can't find a wattage or a laser classification anywhere on the site. I wanted to say that they don't make 1w laser pointers, but I decided to fact check that first.
I was wrong, they do make "laser pointers" that powerful. Browsing their laser safety forum has a post from a teacher wondering what to tell the parents of a rich kid who is playing irresponsibly with a 200mw laser. Someone suggested helping them find a guide dog....
And another person wonders if they should shine their 1w laser back at the neighbors who shine 100-200mw lasers into their house and how may have injured them. I honestly wonder just how far we are from a media frenzied panic that gets nearly everything banned, safe or otherwise.
The voice of reason appears to be some inquisitive teenager, who appears to be more responsible than everyone else. Forget age restrictions, someday we should figure out a way to test how responsible people are and ban people from doing stuff based on that.
35mm slides are quite opaque when showing most images. The only equivalent would be a pure-white scene, which is an extremely far cry from the MGM logo they demonstrated with. You're also comparing LED wattage with laser wattage and claiming the lumens are the same - I doubt they are, though I have no idea what the actual difference is.
But yeah, a 1 watt laser is a massive amount of power. That'd be kinda terrifying to have in one of these.
Not true. Lasers are just light. They can be dangerous because they can focus a lot of energy on a small area, and are actually more dangerous when you cannot see them, but if they're weak enough, you can, in fact, stare directly into the laser with no eye damage. I have done this as a demonstration.
Granted, I was using a weak laser pointer I knew to be safe and I'd never do that for a powerful or unknown laser, but that particular one I used wasn't any worse than staring at an ordinary light bulb.
I should mention that there are "laser pointers" strong enough to be dangerous (e.g. the ones that can pop balloons or be seen from X miles away and whatnot). The one I used was not one of those and I knew that the wattage was low enough to be safe. And I have the eye doctor take pictures of my (very healthy) retinas during screenings, so I'm reasonably sure there was no hidden damage.
Like you alluded to, but I think it's good to be specific, dim != weak[1]. There could be a lot of infrared coming out of a cheap laser device you cannot see. Obviously no one should do your demonstration unless they have the laser device fully vetted by someone who knows what they're doing.
What was the milliwattage of the laser in your demo? I imagine 5 - 10mw is too dangerous, so it must have been really low power.
I don't remember a wattage offhand and I no longer have that laser pointer, but I think it was under 1 mw. But there are other safety factors that can come into play, too. Mostly, it's a matter of how much energy is focused onto how small of an area for how long, not to mention how much of that energy is visible, which is why it's good to know the safety classifications.
There are dangerous lasers, after all and it's a bad idea to be cavalier about eye safety around those. In fact, I saw some just the other day in operation at MakerBench, where they were cutting plastic. The paper covering the plastic was getting set on fire... not something you want shining into your eyes.
EDIT: Reading your article scares me a little. I had a laser from a reputable supplier with an accurate classification. If they're selling crap with no filters like that nowadays, that's a lot more worrisome. People might own a laser that's a lot more dangerous than it's marked as being. Some lasers, especially cheap, "dim" green ones may not be what they're marked as. If it's cheap and not red, it's probably frequency doubled IR, so, yeah, beware....
Make half the fun be the redundant safety systems.