Science fair

Hello everyone!

So I am in high school as you probably could see from profile etc and have been working on building diode lasers and bringing them in to show my AP chem teacher+class and my teacher insists upon me doing some sort of science fair project utilizing laser construction/engineering. This requires typical scientific method research and experimentation. Only problem is I have no idea where to start. I was considering some sort of solid state style laser perhaps with some variation or variable I could work with. So I was hoping that some one here could give me some ideas or where to start. Any suggestions? Thanks for any contributions.

It seems you still haven't received an answer yet, I will try and help you out the best I can in the *diode* department.

If you would like to buy diodes to create a laser for your science fair, this is the place to go!
https://sites.google.com/site/dtrlpf/home/diodes

He offers the following diodes at these respectable powers(to name just a few):
- 4W 650nm
- 300mW 650nm
- 50mW 520nm
- 120mW(New) 520nm
- 500mW 638nm
- 120mW 638nm
- 1.6W 450nm

Umm diffraction gratings? Everyone likes stars. At least I hope so.

You want an adjustable variable though. Umm. You could try slit diffraction. Have a few wavelengths and show what effect changing the wavelength has on diffraction.

Or you know, burning. What burns best and all that. Change the burning target/burning laser.
It'll cost tho.

buy a helium neon laser. this is the best kind of laser for demonstrating how a laser works. just be safe with it. you can buy a cheap one and set it up quite easily. you can easily see how the light bounces between the mirrors and how lasing takes place within the tube.




If you want to do a solid state laser....then it'll look something like this within. not nearly as exciting. the other consideration is safety. A helium neon is eye safe, a burning laser would not be fit for a school project, as it's illegal in public, and I'd hate to see someone get into trouble.

I was thinking gas too. It just screams science fair as stated above. You can go into detail about the inner workings of a gas laser. Throw in some optics and mirrors so you didn't just buy your project.

well, if it were so easy to get a double brewster, you could go into how to set up the mirrors and things, but that's neither cheap, easy, or practical anymore. brewster tubes are rare and fragile, and only made to request now. only sealed mirror coaxial tubes like shown above are really something you can just 'get' now.

but because you can see within, you can go into detail on what a laser is, how it works, and how its different from ordinary light, and it looks cool/impressive. as opposed to a diode laser. with a little luck and time, you could cover a lot more material in a fun, safe manner. If you want info, I'd be happy to help. Between me and a few other members, we could tell you all you could ever possibly want to know about gas lasers. you could build an amazing hene like mine brand new for less than 200 bucks. likely less than 150 if you hunt around, or even less than that if you get it from another member. i've seen people pick up a tube and supply as cheap as 20 bucks before.

DPSS is an option as well, but I (no offense) doubt you could align one, or learn to align one in such a short amount of time, and it'd be much more expensive, and to demo it would involve powerful IR. You can't take something above 4.9mW to a public area, as this is illegal and dangerous.

Thanks for all the replies! As for time I have about a full year to do it. If I were to do some form of material burning I could do the experiment in a private area and then record/photograph results. In the case of solidstate and gas what kind of variable would be changed through experimentation, since demonstrating and explaining that would be a great science project, it wouldn't quite suit the parameters of the science fair. It would be great to have the actual laser there for demonstration but it could probably be done via photograph etc.

Would it be possible to use slightly different mixtures of gases? Then the variables could be concentration of certain gases in the mixture and record/graph changes in output. As for spectrometer/laser power meter, what am I looking at cost wise. I have wanted to get one of each for personal use as well but I don't know where to get/what is the one I should get.

Its possible to change the mix of gases, but you're talking serious money for the equipment and gas to do so. I'm not a gas guy so I can't go in depth with it, but that one is going to be far too expensive for a science fair project...

What about solid state then, perhaps something like varying dopant level, dopant or anything like that?

That won't be happening either, that's even less doable I'm afraid

You could do that but crystals are very expensive. And you'd have to be able to align them.

Though with gas, you could explore how precise the mirrors have to be to get Lasing action if you can find an external mirror tube. (Within 1/2500th of the bore for peak power and 1/1000th to get lasing at all)

Now that's an idea... do it with an argon, see how the alignment affects what lines lase.

ZRaffleticket said:

Now that's an idea... do it with an argon, see how the alignment affects what lines lase.

Click to expand...

The colors are based mostly on the mirror coatings and gas fill. And opening an argon tube is crazy dangerous if you don't know how to handle high voltages...

A hene will often just bite, an accident with an argon will kill and they cost 5x as much... He'd have to learn how to safely work inside the head without zapping himself

Good point. See, this is why I don't do gas

With diode lasers, you zap the diode, the diode dies.

With gas lasers, laser zap you, you die.

Sorry for the off topic couldn't help myself.