pyrotechnics and lasers

[evmsynths]

I have been asked to help out with the pyrotechnics
display for a stage show.

They (producer/director) gave me some lasers
and said can you make them draw some computer
graphics on the auditorium walls and ceiling.
As I know nothing about this I naturally agreed.

They gave me:-
5 PC's
3 635-670nM 5mW red lasers 500m focal range
1 532nM 5mW Green laser 2 mile focal range
1 630-680 3mW Red lasers 500m focal range
Lots if MIDI cable, a sound to light unit (3 inputs)
the use of the onsite electrician and directions to
a local hardware store.

So my question is... what kind of contraption can
anyone suggest I build to physically move the laser
beams around to get some images.
I am thinking, PC->serial/parallel port->voltage converters
->motors->mirrors.
Does anyone have experience in this type of hardware
construction. Sync to the music wouid be a big bonus.
Google seems to just offer prebuilt units out of my
set budget.

Any ideas ?

Regards
Etric

[vurt]

1 532nM 5mW Green laser 2 mile focal range

forget pyrotechnic shows man,you can bring planes down with these

[DWb]

I heard about someone getting good effects by gluing mirrors to cheap speakers and then feeding them the sub bass from the music. Or maybe you could have one speaker for the sub bass pointing onto another for the normall bass. Would that get you a 'scope' effect? *tries to think about it* *fails*

[John Vulich]

Your gonna permanantly blind people in the audience with that setup!

[advaya]

Your gonna permanantly blind people in the audience with that setup!

Good lord yes...

You'll probably need everyone in the audience to sign a waiver before entering... In the event that someone tries to sue for scorched retinas...

[Hink]

no offense, but pyro and having so little experience you ask here on KVR flashes images of Great White and a night club in Rhode Island...I would advise you not to take any advice on the use of these displays from here or any other source similar. You must, and I stress must work with someone licensed to work with pyrotechnics.

The two brothers that ownded the club in the Rhode Island blaze will likely spend the rest of the lives in prison. One brother worked for a local tv station and was a roving reporter (you know the poor sap they put out in the middle of a blizzard to tell us it's snowing) and was quite popular. They'll be sitting in the can right next to the technician. Get your advice from the right source or pardon the pun...you're playing with fire.

[DWb]

no offense, but pyro and having so little experience you ask here on KVR flashes images of Great White and a night club in Rhode Island...I would advise you not to take any advice on the use of these displays from here or any other source similar. You must, and I stress must work with someone licensed to work with pyrotechnics.

From the context, I think the OP meant 'light show' rather than actual fire...

[Hink]

no offense, but pyro and having so little experience you ask here on KVR flashes images of Great White and a night club in Rhode Island...I would advise you not to take any advice on the use of these displays from here or any other source similar. You must, and I stress must work with someone licensed to work with pyrotechnics.

From the context, I think the OP meant 'light show' rather than actual fire...

yeah I realized that too, but the title does say pyrotechnics and that made me ask myself why is he not asking about pyrotechnics. Is it because he actually isn't using any? Or because he doesn't feel he needs the help with pyrotechnics? That's why I addressed just the use of pyrotechnics. Hopefully my point is moot, but in the case it isn't it is an important point....

[Unkie Al]

The devices are called "Galvos", and are just as you describe: motorized mirrors or mirrors coupled to voice coils that react to changing voltages. Do a search for "galvos" on eBay, or look up how to build them out of junked drive coils from CD players.
Of course, it seems to me that, if these guys tossed all that gear your way, they'd have a galvo or two knocking around in the toolbox.
And FWIW, those lasers also strike me as being entirely too powerful for the task.

[Unkie Al]

Oh BTW, galvos are analog devices and can be driven by soundcard outputs.

[snooky]

1 532nM 5mW Green laser 2 mile focal range

forget pyrotechnic shows man,you can bring planes down with these

Battlestar Galactica would have been proud!

[evmsynths]

after more googling...
635-670 3mW is the same as the toy laser pointers
that you can buy from the electrical shops so no
real hazard.

The plan is to sight the rig on the top gantry and
only aim at the ceiling and upper walls about 20
meters above the audience to avoid any line of sight.
For absolute safety I will only point the green laser
at the roof.

Unkie Al:
Galvos look good, but not at $699

DWb:
Mirrors on speakers is a great idea. With the sound
to light unit it could give a cheap audio sync effect also.

I think drawing pictures and/or words is too
ambitious and will try simple geometric shapes.

Some interesting things we tried in the last few
hours are firing the lasers at, on or into...
CD's
Bottles/glasses of water
Glass jars
Mirror balls from the props dept
A small glass cube spinning on a floppy drive motor

We are about to take apart a old pair of binoculars
for the mirrors and lenses to experiment with.

Any more ideas welcome.
Sun glasses optional

Regards
Etric

[Hovmod]

I was a stage hand for Pink Floyd once, and snuck off behind the stage to smoke a joint. The pyro guy was less than impressed, as I lit my weed amidst abouta zillion dollars worth of fireworks.

Cool gig, evm!

[androidlove]

http://www.linux-laser.org/links.php?lang=en

freeware and diy here