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7th Grade Science Fair Project

Hemlock_Mike

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Dave -- Sometime, let Dakota post on here. He's the center of this project.
You can not be the center point, only an advisor.

HMike
 

Duster

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Good Idea, tonight his is at his moms and over this weekend. But he knows about you guys already. Looking forward to next week when he will be home.
 
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sightfx

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Here is a link to 105 ways to use a Laser. http://www.***************.com/forums/showpost.php?p=5562&postcount=1

Edit: OK so there must be some rivalry I don't know about or something because the URL is being edited out. just replace the stars with laser enthusiast all one word.

I know lighting a match and popping balloons is fun bit some of these other ideas are good for science projects.


I personally like #18. Internal Reflections in a Water Jet - When a laser beam is traveling inside a stream of water, internal reflections at the edges of the jet can prevent the beam from leaving the water. This happens whenever the angle of incidence between the laser beam and the normal to the water surface is greater than the critical angle for water (48° ). Punch or drill a 5mm hole near the bottom of an empty 1 liter clear plastic soda bottle. Aim the beam of a laser so it goes into the bottle and out the hole. Fill the bottle with water. When the water emerges from the hole, the laser beam will follow the water jet as it arcs downward. This illustrates the internal reflections that take place in a fiber optics cable.

-Ryan
 
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lasersbee

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Remove the four "*" and paste it into your browser....

ht*tp://www.laser*en*thu*siast.com/forums/showpost.php?p=5562&postcount=1


[Edit]....fixed it...


Jerry
 
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swimminsurfer256

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Remove the four "*" and paste it into your browser....

ht*tp://www.*en*thu*siast.com/forums/showpost.php?p=5562&postcount=1

Jerry
Jerry I think you forgot a word :p
-->

ht*tp://www.laser*en*thu*siast.com/forums/showpost.php?p=5562&postcount=1
 

Duster

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Been working on the mill all day. My friend flies RC Helicopters. When he has a tough landing the main shaft can get bent, just ever so much, then it vibrates any where from a little to real bad. He has a bunch of bent ones, 50 or so. (I think he needs to work on his landing a little more) Anyway you have to buy a new one, no one makes a way to straighten them. So he asked me to make him a truing tool so he can straighten them. So far it looks good, it should work great (will see).

I like making prototype stuff like that. Anyway, like I said before Dakota is at moms this weekend so lasers are on hold until he comes back on Monday. When I get the chance later tonight I am going to look at the 105 ways to use a laser, sounds cool. See ya.
 

Duster

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Hello everyone, Dakota is starting his report. Just the basics mind you. Have a few questions.
He as written: Three basic components of a laser. pump source, gain medium, optical resonator. (correct?)
Our question is: Is the Pump Diode the Pump source? The pump source provides energy to the laser system. This is the internal energy needed to excite the atoms within the gain medium. yes?

Our next question (s) is the Gain Medium the Pump Focusing Lens? Is it something we can point out in a diagram? It helps to see what he is trying to express.

And lastly: is the Optical Resonator or Optical cavity, what holds the mirrors in place? (feel kind of dump on this one!)

We just need real basics, I forget sometimes this is way over his head at this point, so I don't want to scare him with to much this year. We are still popping balloons though and that is cool. He also knows what LASER stands for and is proud of that.

Any help would be cool, findig info from a few sites, like here, How Do Lasers Work?, http://www.repairfaq.org/sam/laserfil.htm,1. Learn Everything You Need To Know About Lasers
 

Duster

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This is the diagram we are using, it may not be the best we could be using.
 

Duster

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High power lab quality 500mW green laser, build that some day!



Specification:
Range: 200 miles
Continuous output power: 500mW class 3B
Laser diode: 2 watts
Power: Mains 120v/240v power supply, (included)
Dimensions: 170 X 80 X 60mm
Laser life: Over 20,000 hours
Wave length: 532nm
Weight: 145gm
Warm up time (seconds): <10
Beam divergence (mrad): 1.5
Beam Diameter: 2mm
Power Supply: 120v AC - 240v AC
 

Duster

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Examples of different gain media include:

Liquids, such as dye lasers
Gases, such as carbon dioxide, argon, krypton
Solids, such as crystals and glasses.
Semiconductors, a type of solid

I think I know what the medium is in a 5mW laser: the Pump Focusing Lens. Right?
 

Duster

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I think.........the Expanding Lens and the Cullimating Lens are the mirrors thus the Optical Resonator or Optical cavity? correct me if I am wrong, not problem. Thanks
 

pullbangdead

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No, sorry, that's not the gain medium. If you want to get REALLY technical, there are 2 gain mediums in your diagram. In these DPSS systems, it's like running 2 lasers: You provide electrical energy to pump the 808nm diode (the materials in the 808nm diode provide gain when pumped with the electrical energy), so the semiconductor material in the diode is a gain medium.

Then that light is focused (that's the Pump Focusing lens) into the 2nd gain medium, which is the Nd:YVO4. The Nd:YVO4, getting pumped by the light from the 808nm diode, then acts as a gain medium for the 1064nm light.

Also, with how these things are built, the gain medium in both cases here is the same as the optical resonator: the semiconductor chip in the 808nm diode is the gain medium and its 2 ends form the optical resonator. Same the the Nd:YVO4, the crystal is the gain medium as well as forming the optical resonator. For the "mirrors" of the optical resonator, they just use the facets of the crystal. The semiconductor/air interface forms the mirrors on the diode, and the crystal/air interface of the Nd:YVO4 crystal forms the mirrors for it. In practice, sometimes this simple interface is enough reflectivity, but often it's preferable to put simple thin film coatings on the the ends of the semiconductor or the Nd:YVO4 to increase reflectivity. In that case, the facets are still the mirrors, but the mirrors are enhanced by the thin film coatings.
 
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Hemlock_Mike

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Dave -- Have you let Dakota post yet? He's the man in this project !!
The info above might be a bit much for now but that is how the DPSS lasers work.
808 pumps the 1064 which is doubled to 532. Simple -- Right?

HMike
 

Duster

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Ahhhhhhhhh pullbangdead, that makes a lot of sense, now we know that he will be able to explain it and put the info in writing. Been looking around today trying find this information out. Thats a fine diagram, but it did not answer our questions nor did the website explain it the way you just did. It might have been there, but I did not see it. Very cool explanation. It will be until tomorrow before he reads this. About an hour or two is about all he can take before he has to go outside and play ball or just have some fun (its the WEEKEND!). I will try and get my head around this tonight for myself. Thank you, Credit DUE!
 




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