Engineering Project--Lasers and Sharks

[The Lonely Protons]

Hello everyone, my name is Josiah Norton.

I am a member of an engineering design team (The Lonely Protons) at Humboldt State University in Northern California. I found this forum as I was searching for some online expertise in lasers, and this seems to be an active community that could provide me with some information and help as we design our project.

That being said, perhaps you're interested in the project, and what exactly we are using lasers for? The answer is something like this:

My design team was issued a task. We were to provide an interesting graphic display for real time energy use at a local charter school. The display has to be as close to real time as possible, and understandable by all ages. We have the monitoring system pretty much dialed in, and I am researching lasers for part of our graphic display, which brings me to the part you're probably reading this for: sharks and lasers!

Our display's general idea is to have an object that glows a color that is linked to the energy usage at the school. For example, if the usage is above a predetermined threshold, the object will glow red; if the usage is below that threshold but above another, it will glow another color, and below that threshold, yet another color.

The fun part is how that object glows, and where that object is. The idea is this: we have a cabinet with a transparent front, and a fish tank inside that holds the object. The fish tank will house...you guessed it...sharks! Well...we aren't sure that we can pull off a saltwater aquarium in the long run, so we will be finding a fish that looks like a shark but is freshwater...but that's besides the point. Sharks and freakin' lasers! But I digress.

There will be several different colored lasers inside of the cabinet that are controlled such that they turn on depending on the energy usage. The beams from those lasers will bounce off of x number of mirrors and be directed into the object that glows inside of the tank.

Now here are my questions for you laser experts/enthusiasts.

1. In order to have the laser beams visible, I understand that we will need a combination of lighting conditions and laser power. We are thinking of having one way glass, so that the lasers are in a dark environment, but their beams will be visible on the outside. Anyone know if this works?
2. If the one-way glass thing won't work, is there something else that would? If we can't limit the light, what kind of power do we need to have clearly visible beams?
3. We are thinking of using a quartz crystal as the object that glows. I have seen a video on youtube ([https://www.youtube.com/watch?v=oBqFJknNyLQ]) that shows this working, but he is holding the laser directly to the crystal. Will the beams be powerful enough to light up this crystal after they have been redirected off several mirrors?

Thank you very much for your time. I appreciate any input you may have, and I also appreciate it even if you've just taken the time to read this.




Cheers on behalf of The Lonely Protons and myself,
-Josiah Norton

 

[Optik Illusion]

You know, I have one simple request. and that is to have freaking sharks with laser beams attached to their head. now evidently my Cyclopic colleague informs me that cant be done.

 

[daawood123]

Wait, so whats the point of the sharks? and how big will the aquarium be?

 

[ZRaffleticket]

Regarding the light and 1-way glass: I have no idea. If it doesn't work you could always do this.

If it doesn't change the experiment too badly use small amounts of fluorescent dye and use a 445nm laser (or 405nm), the beams should show up nicely. (as these wavelengths will excite fluorescent materials) Just getting some dye out of a highlighter should do.

If you go that route, make sure your diode is a single mode diode (perfectly round dot) - 405nm lasers are almost always single mode, if you want to use a 445nm diode (it will be more expensive), use an orsam PL450B.

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As for the quartz, as long as the crystal doesn't have a perfect structure (and the laser spot beam remains intact after the mirrors), you should be fine. You'd want to make sure your water is as clean as you can get it (obviously), and you'd want to make sure your mirrors DO NOT have glass coating in front of them. (all mirrors do, but not both sides of all mirrors do) I can't remember the name of this mirror for the life of me but it's used in nearly every laser-mirror-related application.


Hope I helped a little, the best thing to do is experiment in this case because it's not necessarily a common project.

 

[The Lonely Protons]

Hey, thanks for the replies.

daawood213: The point of the sharks is literally just for the interest factor. They don't directly add to the ability to interpret the data, but an aquarium in just about anywhere is a draw; the more people that come to look at the display, the more that are aware of the energy usage as well. The tank will be somewhere in the realm of ~50 gallons, it looks like.

ZRaffleticket: I did some research, and the one-way glass idea won't work due to the nature of how the stuff works. It doesn't alter the amount of light that passes through in the manner I had thought.

As for the dye idea...that may work, but I think that it's not totally clear on where the lasers are traveling. Prior to entering the tank, and going to the prism, the lasers will be passing through air only, and will be redirected with mirrors. When the lasers enter the tank, they will be traveling up through a tube that has no water in it, until they make contact with the crystal, which will be sitting on the top of the sealed tube. The tank will have a hole in the bottom that this sealed tube goes through.

Thanks for the tip on the mirrors. Let me know if what I've said changes anything, or if you have any other tips.


Edit: In consideration of the mirrors: The accuracy and the amount of diffusion we encounter may not be as important as in some applications. We need our mirrors to reflect enough of the laser through several deflections to be able to still see the beam, and to hit a target that is at least 1.5" in diameter. Should I still be looking at such high quality mirrors, or do you think a standard mirror would work?



Cheers,
-Josiah