How safe is Laser Graphics on a Hot Air Balloon?

[kamakajee]

Hello All,
I have an inquiry for projecting laser graphics on an inflated Hot Air Balloon, I plan to use a 500 to 1000mW green laser for the purpose.
My concern is :-

• How safe is it to use a laser onto these babies
• Is there a distance that I should keep in mind from where I where I would be projecting.

It is a projection onto the hot air balloon & not from inside.
Any help will be highly appreciate, the sooner the better as I have to let the organiser know with 24 hrs... sorry for rushing things !
Cheers!
Kama

[colouredmirrorball]

Do you fear that the laser light might harm the balloon? If your beam is super tight and you use hot/stray/static beams on your balloon then there might be an issue, but otherwise not really. If the balloon is at reasonable height there is no problem.
Will there be a person in the basket of the balloon? I don't know the regularisations where you are but my guess would be that if you give that person safety goggles it should be ok as he is not a part of the crowd.

[kamakajee]

Hi C.M.Ball.. thanks for the super fast response .. yes I fear the beams might have an adverse effect on the balloon cloth.
The balloon will not be up in the air.. though inflated, they will be stationed on the ground & I have to do the graphics on it.
Is there any recommendation on the power of the laser that I should be using plus if any suggestions from what distance.
I can be real close to the balloon say around 10 meters to get the desired size & have checked a 200mw laser too is good enough.
It is not a real graphic show but the laser beams are the part of the show. & I guess there won't be anyone inside the basket.
kama

[colouredmirrorball]

Again I'm not an expert on legal issues in the States so you should inform yourself better at this, but I've always heard that the projector needs to be 3 meter above the audience (or was that 3 meter above the floor?) so if the balloon is on the ground you need to consider this as well.

Also, there are lots of laser show regulations in the US. Have you taken them into account? For instance your projector needs to be varienced and stuff.

In my opinion the laser won't affect the cloth (unless the balloon is made out of super heat sensitive material which I doubt because a balloon is filled with hot air anyways). But if you shine a static 1 W beam onto the cloth for long enough then you can melt it, but as long as you are scanning there shouldn't be a problem at all. After all, a 1 W laser can be used to safely scan a person's retina so I'd assume the much firmer balloon material will hold on better.

[kamakajee]

Hi CM Ball, Yes I know the precaution procedure & all that is taken care off.. just the concern is for the hot air balloon cloth.

[WookieBoy]

Hi Kamakajee.

The cloth will be fine unless you're dumping alot of wattage in a tight beam.

These cloths are designed to withstand heat and to a lesser extent flame for a short period of time.

Unless you dump all the power from your laser into a single beam spot (or using a weird UV laser), you're very unlikely to harm the balloon!

[kamakajee]

Hmm.. so even if it is a 200mw there are chances of a damage?

[Stoney3K]

Hmm.. so even if it is a 200mw there are chances of a damage?

Strictly speaking, it depends on the colour of the laser, the colour of the balloon cloth and the amount of heat sinking (air flow) around it.

If you have a 200mW green DPSS on a white balloon, it's not going to leave a mark. No matter how hard you try, because the cloth is white, it will scatter most of the laser power back off the balloon, towards the audience (which is what you want, since it makes your graphics visible), and only a tiny fraction is absorbed heating up the balloon's cloth. Now since that thing is outside and there will probably be some wind passing through or over it, there will be no damage even on static beams.

If you have any doubts, try and ask the balloon's manufacturer for a cloth sample and abuse it with your laser.

On a black balloon there may be more trouble if you have static full-power beams in your image and there is no air flow. 200mW may be able to damage some plastics, depending on material type and thickness, but I've (accidentally) shot my 400mW 445nm at quite a few black objects and the only thing affected is duct/electrical/gaffer tape which is fairly fragile plastic film with no heat sinking.

Trying to burn a hole into something light-coloured is going to be very difficult, with a black or dark coloured object it's a lot easier because all of the light will be absorbed, not scattered back off. Again, I'm taking the worst case 'static beam' scenario as a bench mark here.

I can't comment on any legal issues since I'm not a US resident.

It does give me an idea with some semi-transparent PVC inflatables for use in a show though.

[kamakajee]

Hi Guys,
Thanks a lot for all the reply.. much appreciated!
Stoney a BIG thanks for the detailed explanation now I can pitch in with confidence
Cheers!
Kama

[Picasso]

You will want software or hardware that can do geometric correction if your going to project gfx/animation on the balloon and want people to work out wtf it is your projecting.