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7th Grade Science Fair Project

Duster

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Hello everyone! My name is David, my son is Dakota. He has a science fair project to do in school and after seeing a video on Youtube by chance (one that everyone has seen, I am sure) He wanted to light matches on FIRE with a LASER! Cool I replied, lets do it. So without any further research we started in, I bought 7 of the cheapest 5mw 532nm Green laser pens we could find on Ebay. The guy in the video said thats all we needed! (haha) So we built the test equipment (thats been the real fun so far) and then took apart three of the lasers and mounted them. As you can imagine, "What?, they don't work?" They don't lite the matches!?

We did everything that was shown in the video. I had bought 7 pens so we could have some to screw up, and a few extra in case we really screw up. Well we have some cool test equipment and learned a lot about lasers for sure. He is a little disappointed, but like I told him "The light bulb was not invented on the first try!" Got to stick with it and learn from your mistakes and be willing to, never GIVE up.

I have spent the day today myself looking over this forum and what an education this is. I also have down loaded a bunch of info on how lasers work. It will be a great science fair project, even if we don't light any matches on Fire! I downloaded some pics of the test equipment we built if anyone is interested is seeing it. Kind of cool. We will stay in touch and update as things progress, See ya, Dave and Dakota
 

Hemlock_Mike

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Dave & Dakota ---

It's sad how much crap about science is out there. I'm glad you did the research however and found some knowledge to show.
You can't combine 5 mW pointers into a "death star" arrangement to light a match.

However, popping a black balloon MIGHT be possible if one of those pointers gets to about 50 mW. You will have to carefully focus it with a magnifying glass to a tiny point. Some pointers do go above spec and one of yours might do it.
Hope your son learns a little hands on science. That's where it all starts. I wish more parents were as involved as you.
HMike
 
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get safety goggles.

and if you really want to impress, since i know everyone has seen red laser, alot of people have seen green lasers, why not do a blu-ray.

like the phr803. 110mw is enough to light some matches.
 

Duster

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YES, safety goggles are a must! I think what it will end up being is "You can't use a 5mw Green laser to light matches and why" Got to go with the flow!
 
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Duster

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Learning curve! yes you are so right. But then we did get to mess up a bunch of cheap lasers, that was kind of fun for the price.
 

Hemlock_Mike

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I just popped a balloon with 35 mW of green with a 2" FL plastic lens. This done over 6" and because the balloon is black, limited reflection.

HMike
 

Duster

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thats cool, I think we will look into that. Where did you get all the components for doing that? Like the 2" FL plastic lens?
 

Hemlock_Mike

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The 35 mW is a cheap pointer rated at about 25 mW but puts out more. The lens I got from DX over a year ago. If you need a lens, I'll send you one but you need a solid 20 mW minimum to make it work.
Balloon popping impresses the masses and is a pretty safe demo at low power.

HMike
 

Duster

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I will do that, can I order the laser from DX right? And thank you for your offer. I will let you know when I get the laser, I posted some more pics, these are of Dakota.
 

Hemlock_Mike

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DX won't import those lasers to the USA.
Look on these forums for O-like or Rayfoss or someone like that. Maybe someone else will help here too. Maybe one of what you got will do the job with a close focus lens. Looks like you have a variable power source for the lasers. I don't know how much current you are providing and at what voltage. Many pointers "benefit" from e2 cells measuring 1.7 volts per cell. Some of these 5 mW lasers wake up with 3.4 volts!

HMike

Test -- Put a small black dot on your wrist with a sharpie marker. Shine the green laser at the dot from 1 to 3'' -- do you feel the heat? I mean inches!
 
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Duster

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We are using two 1.5v C8 Duracell batteries per laser. I wanted each laser to have its own power supply.
 

Hemlock_Mike

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Read above -- Lithium Ion Duracell e2 or ultimate cells.
Try the black dot test. If you feel heat is a second, the lens trick should work.
HMike
 

Duster

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See there ya go, I learned something again today, thanks so much. He will run some more tests. Then see what happens.
 

Duster

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Oh, where would you buy the goggles? I can find them but what would you recommend?
 




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