Laser Art Exhibit

[rickyk586]

Hey everyone! I'm going to a 3 day art event called Youtopia in San Diego. It's similar to Burning Man but much smaller.

My idea for an exhibit to bring was involving lasers, because they're awesome and everyone loves them :). There are a bunch of trees around so my plan was to have laser beams bouncing between mirrors attached to trees. So, I bought 10 cheapo green lasers ($5.40 a piece), 100 3"x3" mirrors, and refrigeration hose for attaching the mirrors to the trees and allowing us to bend and adjust the mirror angles.

So we tried it last night in a park and came across a couple problems. One is that the lasers became pretty dull after about 10 minutes. After some googling I see that they are not designed for continuous use at all. So my first question is: Is there a way I can keep these lasers on for a few hours? As far as batteries go, they normally take 2 AAAs so I rigged up 2 Ds instead which worked, but after about 10 minutes the laser got pretty hot and it also got pretty dull. I was thinking maybe they got dull because of the heat, but they also got dull using the AAAs but it didn't get hot (only slightly warm). After cooling down, the laser worked normally. I understand that continuous use will also shorten the lifespan of the lasers, but I'm not too concerned about it because of how cheap they were.

The other problem we had is not nearly as important, but I figured I would still ask about it just in case anyone had any pointers. The glass on the mirrors is kinda thick and therefore only allowed the laser to bounce off of maybe 4 of them before the beam was not visible anymore. Is there anything I can do about this besides buying much more expensive mirrors?

Any input you have is appreciated. Thank you very much! Also I can provide pictures if anyone asks.

 

[hellokitty[hk]]

Might help if you add some smoke?

 

[Eidetic]

Mirrors for reflecting laser light are coated on the front surface, not the back, and are often made to reflect >90% of the light. Cheap back surface coated mirrors will degrade the beam as you see. Good mirrors can be found cheap inside old overhead projectors or rear projection TVs.

You need a "lab" laser that plugs in, not one designed to be handheld. Anyway, you're proposing a very dangerous thing to do with laser light. Mirrors mounted to tree branches can and will move out of alignment, regardless of how well you mount them. Trees move. The beam can go anywhere. Not a good idea with a beam powerful enough to see off to the side, unless professionally done (and even then, sketchy).

 

[rickyk586]

Mirrors for reflecting laser light are coated on the front surface, not the back, and are often made to reflect >90% of the light. Cheap back surface coated mirrors will degrade the beam as you see. Good mirrors can be found cheap inside old overhead projectors or rear projection TVs.

You need a "lab" laser that plugs in, not one designed to be handheld. Anyway, you're proposing a very dangerous thing to do with laser light. Mirrors mounted to tree branches can and will move out of alignment, regardless of how well you mount them. Trees move. The beam can go anywhere. Not a good idea with a beam powerful enough to see off to the side, unless professionally done (and even then, sketchy).

Thanks for the mirror tip. I might have to look into finding broke rear projection TVs.

The 10 lasers I bought are all <5mW (well, rated as so at least), so I'm not too worried about the safety of it. We will be fixing the mirrors to the trunks of the trees, 1' to 8' from the ground, so we're not too worried about the trees moving either. During our first trial, we were able to successfully mount the laser and 4 mirrors and were able to still see the beam, granted not very well and not really from 90 degrees, but still good enough for us. So, we would still like to be able to use the 5mW lasers if there's someway to keep them on for extended periods of time. We might look into passive heatsinks, and possibly using a resistor for the D batteries.

 

[bshanahan14rulz]

Green lasers can be finicky sometimes, just due to their nature. You may be able to find a 12mm heatsink for your green modules, but this may or may not help stability.

first surface mirrors, as Eidetec mentioned, would be best, and very helpful. TVs would be the best source, since they would be coated for visible light. Some laser printers will have mirrors that should do OK for visible green. HD platters can be used in a pinch, too, although they can be fairly lossy as well.

Would be best to keep horizontal lasers away from eye level, is a main rule when dealing with stationary lasers. Would recommend goggles for everybody involved. When you know you are in a safe spot and nobody's making adjustments, you can take your goggles off and admire your art, but how will you admire your art if your art blinds you?

 

[Eidetic]

Would be best to keep horizontal lasers away from eye level, is a main rule when dealing with stationary lasers. Would recommend goggles for everybody involved. When you know you are in a safe spot and nobody's making adjustments, you can take your goggles off and admire your art, but how will you admire your art if your art blinds you?

The first sentence above is right on the money, regardless of the laser power in use. The bit about goggles is ridiculous (nothing personal). There's waaaaaaay bigger risk to your eyes from the branches when mounting the mirrors than from the low powered laser you're planning to use.

 

[Changchung]

If you can add a sound activated module, that way you can avoid the overheating...


Sent from my phone with camera with flash and internet on it... :D

 

[rickyk586]

Hey guys thanks for all of your help last year. We ended up not being able to solve the overheating problem in time so the project was put on hold until next year (which is now!)


Following the advice, this year our plan is to just have a box (maybe 3x3 ft.) with the laser bouncing around inside. We don't have a plan yet, but we're thinking just something simple like this.


Whatever we end up doing, the main ingredient is a beam producing laser that can stay on over night and won't overheat. Do you guys have any recommendations for that?

 

[bshanahan14rulz]

You'll want a custom build, cheapest way to get a laser with that kind of duty cycle. Think Aixiz 12mm module-based laser (a common and easy-to-work-with configuration for custom lasers), bolted to a large heatsink or brick of metal.

Confining yourself to a box would be the easiest and likely safest way to create this. I imagine a sturdy box full of mirror pieces (like a disco ball), with laser and mirror pieces mounted sturdily to the box. Then, you can let the beam do its random bounce thing, and find a good spot to make the beam stop. You can stop the beam by drilling a hole in the box for the beam to pass into, and find a safe way to terminate the beam with something that won't burn up.

Again, I do recommend the use of goggles, esp. during the setup phase, but if your mirrors, box, laser, etc., are sturdy enough, you shouldn't need goggles once the artwork is complete (and isn't shooting beams out in random directions).