Science Fair

[ringo42]

My son signed up for the science fair and said he would be testing a laser with convex vs concave lenses to see which would pop a balloon better.
Can someone point me to a laser that will definitely pop a dark balloon, and a couple lenses that he can experiment with please. I see alot of the lasers are focus-able, but I think he wants external lenses.
Any help will be greatly appreciated

 

[Deleted member 16589]

Um thats not a good idea A laser that can pop a baloon will be to dangerous for a kids science fair.
The reflection off the balloon or any reflective surface could blind someone who is not wearing goggles.

 

[H2Oxide]

My son signed up for the science fair and said he would be testing a laser with convex vs concave lenses to see which would pop a balloon better.
Can someone point me to a laser that will definitely pop a dark balloon, and a couple lenses that he can experiment with please. I see alot of the lasers are focus-able, but I think he wants external lenses.
Any help will be greatly appreciated

I'd say any laser that's 200-300 mW would have no trouble popping a dark balloon. If it's for an experiment I'd get a lab style module rather than a handheld. Here's a 250 mW red laser from O-like.

They have mixed reputation here, but even if the laser doesn't meet specifications it should still be able to pop a balloon.

Meredith Instruments has some nice optics assortments. The mounted ones will obviously be easier to use, though they are a bit more expensive. It also seems like the majority of their lenses are meniscus, AKA both convex and concave at the same time. You could also buy the lenses directly from Thorlabs or Newport for $20-$30 each, just type in "plano-convex lens" and "plano-concave lens" in the google shopping tab.

Keep in mind that lasers of this power can blind you, even with reflections. So make sure everyone present while doing the experiment is wearing appropriate eye protection. Stay safe, and best of luck at the science fair!

 

[tuskiomi]

So long as the laser is below 200mw, make sure everyone has a pair of goggles that are made for the correct color. For red lasers, something like
this would do nicely.

 

[Deleted member 16589]

I'd say any laser that's 200-300 mW would have no trouble popping a dark balloon. If it's for an experiment I'd get a lab style module rather than a handheld. Here's a 250 mW red laser from O-like.

They have mixed reputation here, but even if the laser doesn't meet specifications it should still be able to pop a balloon.

Meredith Instruments has some nice optics assortments. The mounted ones will obviously be easier to use, though they are a bit more expensive. It also seems like the majority of their lenses are meniscus, AKA both convex and concave at the same time. You could also buy the lenses directly from Thorlabs or Newport for $20-$30 each, just type in "plano-convex lens" and "plano-concave lens" in the google shopping tab.

Keep in mind that lasers of this power can blind you, even with reflections. So make sure everyone present while doing the experiment is wearing appropriate eye protection. Stay safe, and best of luck at the science fair!

If he is persistent on doing it 50mW will pop a balloon so I would say around 100mW would be best and stay lab style No handheld.
I would still advise against this experiment because all it will take is one idiot to grab the laser or stick something reflective in front and hit someone eye and they would be blinded.

 

[H2Oxide]

If he is persistent on doing it 50mW will pop a balloon so I would say around 100mW would be best and stay lab style No handheld.
I would still advise against this experiment because all it will take is one idiot to grab the laser or stick something reflective in front and hit someone eye and they would be blinded.

True, but the more power it outputs the faster the balloon will pop, adding to the "wow" factor. The one I linked probably doesn't output 200 mW, but as I have never ordered from O-like I can't say how well they preform. If you're really adamant about doing this experiment actually at the fair, you could set up a transparent acrylic or plexiglass box to do it in, preferably the opposite color of the laser to add protection, and lower the risk of someone grabbing it or putting something in front of it.

Also, the goggles tuskiomi linked will be adequate for observers, however I wouldn't recommend using them when actually modifying the beam, especially if you do go with a higher power. Something like this will be more than enough protection.

 

[starlight]

Surplus Shed is great for cheap priced optics

 

[trussmonkey25]

You could always strap down the Laser to a large piece of plywood, and set up lens mounts, fog machine, Beam stop etc cetera. It could be a nice father/son project.

 

[RedCowboy]

I would not take a laser of any kind into a public school without written permission from the school.