Laser for education

[THLL]

Were doing a experiment in class the consists of lighting a small firework in a closed container. Now the point of the experiment is to detonate the explosive and watch it in slow motion to understand some physical laws such as thermodynamics and ideal gas law.
(This is under the supervision of a professional and safety is the prime concern)

Im looking for a laser the can detonate the fuse. Now the laser should be able to light the fuse through a 1/2-1/4inch clear plastic. The laser will also be against the plastic or a couple inches from it.

Budget of about 150$

Ps if it can be ir that would be a plus!

 

[pschlosser]

light the fuse by overheating a thin wire (with current) twisted around the fuse.

the laser has little educational value in the experiment described.

 

[ZRaffleticket]

Unless he discusses heat transfer, % absorbed and such. I think it would make a neat experiment if you tried it with 650nm and 405nm. (note these two wavelengths are best for burning due to the beam specs, and there should be an apparent difference if both are the same power. 100mW should be enough)

You can get 650nm and 405nm focusable lasers easily within your budget. I'd recommend lazerer.com or o-like.com. Make sure the lasers are focusable! Since you're doing this in a demonstration, make sure you have the focal distance set up ahead of time and have no stray reflections pointed toward someone or else you'd need to get a shield of some sort to protect the observers' eyes, if the laser can light things on fire it can easily cause permanent damage if used unsafely...

But if you're looking to ignite the fuse quickly in a confined space, the wire is probably the safest option.

Edit: why IR? those are inexpensive but also the most dangerous...

 

[THLL]

There are plenty of safety precautions with this experiment. In fact the nearest person would be 50ft away. The wire would be a great choice but the sensors we are using are extremely metal sensitive. To make the experiment as accurate as possible we can not use anything else but the firework. This is why we thought the best way to light the explosive would be with a laser

The reason for ir would be so the camera wouldn't see the laser. Pretty much trying to see only the explosion but this isn't required it would just be a plus.

Alright so im shopping for a 650nm or 405nm with at least 100mw of power (focusable) . Are you certain this would go through the plastic container as well? Would it burn though the container first?

 

[ZRaffleticket]

Believe it or not, the camera may actually pick up the IR light better than the human eye, not many cameras are filtered for it (though, if you're using a high speed camera it's probably filtered, but those shouldn't get saturated by the light from the laser either)

If you go for the 650nm, 250mW would be the most practical as the bare cost of the components would be the same as 100mW. The only price differences will be because 100mW < 250mW, and people fall for it

405nm, 100mW should be plenty as materials tend to absorb this wavelength better than most others. To be safe feel free to increase power if nobody is at risk for getting a reflection, shouldn't be too much more costly.

At $150 you can simply buy a 1W 445nm blue laser off the forums with $50 to spare, burns nearly anything but the beam shape is horrendous.

 

[THLL]

Believe it or not, the camera may actually pick up the IR light better than the human eye, not many cameras are filtered for it (though, if you're using a high speed camera it's probably filtered, but those shouldn't get saturated by the light from the laser either)

If you go for the 650nm, 250mW would be the most practical as the bare cost of the components would be the same as 100mW. The only price differences will be because 100mW < 250mW, and people fall for it

405nm, 100mW should be plenty as materials tend to absorb this wavelength better than most others. To be safe feel free to increase power if nobody is at risk for getting a reflection, shouldn't be too much more costly.

At $150 you can simply buy a 1W 445nm blue laser off the forums with $50 to spare, burns nearly anything but the beam shape is horrendous.

Awesome this experiment is gonna be great. Thanks again!

 

[HippyHop]

At $150 you can simply buy a 1W 445nm blue laser off the forums with $50 to spare, burns nearly anything but the beam shape is horrendous.

I dont understand why you would advise using a monster lazor to do the work of a 100mW 405nm lazor. :thinking: Everyone in the room would need goggles. Reflections would be abound. Also there are many cheap alternatives that are completely safe. Why not extend the fuse out of the container...and use a match? Or use a longer fuse...light it...and place in the container? A 1W lazor is complete overkill for this application...and could easily cause injury.

 

[ZRaffleticket]

That bit was there as a last resort, also just to say things are cheap these days