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Laser Art in Science Class?

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Hello All,
Thanks for reading, and let me first start by saying that I know very nearly nothing about lasers. But I have an idea for a project including lasers and crystals to illustrate the idea of refraction. Here's my plan:

- Build an open cage from wood (just 1x1 plywood on top and bottom held up by dowels.)
- Suspend a high-optical quality crystal from a thin string or fishing line from the top of the cage
- Build small wooden stand for laser pointer and direct the beam into the crystal
- People can play with the crystal, moving it through the laser and watching as the light is absorbed and diffracts.

My questions:
- Would this be even remotely safe?
- Would I basically just need the lowest powered laser pointer I could find to produce light, since I don't need it to actually 'do' anything?
- What kind of lasers could I use for different colors? I think it would be nice to eventually have something like this with different colored lasers interacting in the same crystal to produce interesting light effects.
- What am I not considering here? The amount I don't know about lasers could fill an ocean...

I appreciate any insight and expertise you can provide. Thanks again!
 

DrSid

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If you want the beam to be visible, in thin air .. in bright lit room .. you will need high, not-safe power. But you can make the beam more visible by using smoke machine and dark room, or crystal which is not perfectly clear.
Green is the best visible color. Powers up to 5mW are considered safe. Problem is it is hard to get 5mW green, which actually is 5mW.
You can also get 5mW reds, which are usually on specs, and very cheap. They are much less visible at the same power though, especially the beam.
Other colors are a lot more expansive.

So I say your best bet is to get certified 5mW green .. and adapt the scene to improve beam visibility. Unfortunately I don't have source of such lasers at the moment. Maybe some other members can help ..
 
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hwang21

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LaserGlow has a lot of 5mW green lasers... laserglow.com Wicked Lasers sells a 5mW green laser called the Core... wickedlasers.com/core

Both have APC (auto power control) to ensure a 5mW output.
 
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It's not imperitive that the beam be visible in daylight, only that the crystal be lit while it's in the path of the beam. Sid indicated that a clear crystal would make it hard to see the beam; I am guessing then that a natural crystal with inherent imperfections would produce a better 'glow' effect inside the crystal?

Are other colored lasers so terribly expensive? I am hoping that I can get a very low powered red, green, yellow and blue for fairly cheap. I read around here that often building your own lasers is more cost-effective; I'm not abject to this, I just don't know where to start!

The end goal of this is going to be for kids to play with, so it needs to be 100% safe and not require the use of eye protection. If I used a higher powered laser, could I build a transparent enclosure to protect the viewers? What would such an enclosure be made from?
 

ZRaffleticket

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Red and green you wont have any problem finding, yellow and blue however-- not so cheap.
 

DrSid

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Yes, we build lasers .. but the weakest reasonable build would be 200mW red .. we do also 700mW 405nm or up to 3W 445nm or even more .. those are all very strong lasers.

You want 5mW at max, and there is no sense in building those. Well you can buy the stand alone modules real cheap, which contain all circuitry, laser itself and optics .. all you need is to provide power source and some housing. But even with the modules there will be problem with power .. lots of them are lot stronger then specified.
 
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Antharak

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What you could do buy a 650nm red pointer. Check to see if there are any members in your area that have a LPM and get a reading of what the pointer is putting out.

http://laserpointerforums.com/f70/now-40-listed-list-lpf-members-lpms-locations-81288.html


If it's too high get a neutral Density Filter, to bring the power down to a safe level.
They are not cheap but they will make the setup safe.
This group would work for red.
Thorlabs - ND Filters: Unmounted, AR Coated for 350 - 700 nm

If you do go this way make sure the filter can not come off. High grade Epoxy or something as strong.

This is some work I did with a crystal in water with fluorescent dye.


http://laserpointerforums.com/f48/first-try-posting-pics-81975.html
 
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Lazerbeak

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If all else fails, Radio Shack is convenient and has a red and green that should be on spec. $40 and $60 respectively. Convenience stores, Walgreens and the such sometimes have cheap red laser/led combos $3-$5 if you can find them.

I have a natural quartz crystal that just lights up great with a little laser light :D An enclosure with some glycerin fog might make for a nice display. Good luck look forward to seeing the end result.

~ LB
 




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