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Making a Homemade Laser Question

  1. Jun 5, 2012 #1
    ***Note: I am not trying to make a laser that I can sell or profit from (well at least not now anyways :biggrin:); I'm just focusing on trying to make a laser that is crude and simple, but also one that I can be proud of; thanks.***

    I have done a decent amount of research on lasers, and really, I think I understand the basic principle, but what really bugs me is how to get the right medium-gain material, and how to charge it with the so called "laser-pumping" technique (I know that might not be the correct terminology, but I'm trying my best to convey my thoughts. I'm a newb after all :smile: ).

    Anyway, if I understand correctly, theoretically, you can grab a crystal (say something like quartz), put that in the middle of your two optical lenses, and that will be your medium-gain material, right? Then my next question is could you charge (laser pump) it by sticking a wire with current into it, or no (again forgive me if that is a dumb question)? And if that is possible, then how would you apply the initial light source (the initial light that is to get amplified by the bouncing back and fourth between the medium gain and the mirrors)?

    I guess that is one thing I also never truly understood about the most simplistic types of lasers, which is where would you put the initial light source; it seems if you put something like a light-bulb in the middle, then the object itself that is creating the initial light (the light-bulb) would block the light from entering the medium gain at one of the mirror ends of the laser. Could anyone tell me if I'm understanding this concept correctly or if i even need an initial light source in the first place?

    I know some people will suggest skipping the hardship, and using flash-lamps to act as the laser pump combined with a gain-material, but the problem with them is that they don't last long enough, and with the amount of times I hope to use my laser, I'll end up paying more for the flash-lamp replacements, then I will if I would have just bought a full commercial laser (that maybe a bit of a stretch, but you get my point).

    Really, I just want answers to my questions. Most importantly, I want answers that are not a simple "no, you don't understand anything." I want answers that teach me the correct thinking, the right idea. I want to learn, not be ridiculed for my lack of understanding, as I have been on other forums. So, if anyone could help me out with this, then I would be truly grateful.

    Thank you,
    - Curious_Dude
     
  2. jcsd
  3. Jun 5, 2012 #2

    sophiecentaur

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    Did you ever Google and find this link?
    It appears to be very informative and gets a project like this into perspective.
     
  4. Jun 5, 2012 #3
    Hello sophiecentaur,

    Thank you for the reply! I have skimmed through the link you gave me, and it was quite informative and did put things into perspective to an extent, but had almost none of the answers I was looking for. I should have mentioned, and it was probably my fault that I forgot to mention, that I am looking forward to building a SS laser (solid state laser), not just any other type laser that uses gas, etc.

    The undertaking of making a non-SS laser for me is beyond me; the use of transformers and super-conductors for some models is just information and tinkering and meddling that's not even close to my league of knowledge or capability (not to mention, somewhat out of my price range, although the SS laser can be pricey when looking for specific gem sizes, shapes, and other specifications).
    But, the point is, I still really want answers to my specific questions (in my first post). I want to see if I can create a SS laser without the need of a flash pump; I want to know how I can make it work; And, also, if I even need a "YAG rod?"

    I mean in theory, even if you to bounce light through a medium of energy, back and forth between three mirrors, and then wait until the light gets enough energy, tilt one of the mirrors, causing the light beam to go into a different direction, you would have essentially created a laser. Am I right? Or I am I just speaking gibberish with technological terms? I just want to know.

    Again, thank you for your reply,
    -Curious_Dude
     
  5. Jun 6, 2012 #4

    Bobbywhy

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    Not quartz.

    “Examples of active laser media include:
    Certain crystals, typically doped with rare-earth ions (e.g. neodymium, ytterbium, or erbium) or transition metal ions (titanium or chromium); most often yttrium aluminium garnet (YAG), yttrium orthovanadate (YVO4), or sapphire (Al2O3);[1]
    Glasses, e.g. silicate or phosphate glasses, doped with laser-active ions;[2]
    Gases, e.g. mixtures of helium and neon (HeNe), nitrogen, argon, carbon monoxide, carbon dioxide, or metal vapors;[3]
    Semiconductors, e.g. gallium arsenide (GaAs), indium gallium arsenide (InGaAs), or gallium nitride (GaN).[4]”
    Liquids, in the form of dye solutions as used in dye lasers.[5][6]
    http://en.wikipedia.org/wiki/Active_laser_medium

    Probably you’ve studied these other websites already:

    http://en.wikipedia.org/wiki/Laser_construction
    http://www.rp-photonics.com/ceramic_gain_media.html
    http://www.davincisworld.com/Light/LaserTutorial.htm
    http://en.wikipedia.org/wiki/Solid-state_laser
     
  6. Jun 6, 2012 #5

    sophiecentaur

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    @Curious_Dude
    I went to a lecture on lasers not long ago and the guy 'made' a laser with some Jello and a camera flash, to pump it. Needless to say it was rubbish but it made a point. I have also seen an 'air laser', made with a low pressure discharge tube and mirrors (nasty UV, I believe - so not to be recommended )
    From what you write, I suggest that you look more into the details of actual laser operation. Your 'mirrors' scenario is a bit suspect, I think.

    There are two ways of getting energy into a laser. A flash pump - which can get your energy into anything you want, because there's no connection problem, or an electrical supply. Relatively easy for a gas discharge tube, as all you need is a container, a vacuum pump and a High Voltage supply. If you want a solid state, continuous laser then you need high tech lab to make your diode (which you ain't got and could never afford, I think).
    I suggest you look on DIY laser sites in which (several well-informed) people have gone through all the developmental routes. This is far too hard to jump into wioth no previous knowledge, I think.
     
  7. Jun 6, 2012 #6
    @Bobbywhy: Thanks for replying! I have read those sources already, and I could have sworn I saw the mention of quartz somewhere, but now that I have read them again, I can't seem to find it. Maybe when I read the word "crystal," first thing that came to mind was quartz. This is exactly why I go to forums like these, to avoid misinformation from sources as well as my own stupidity. So, thank you for that correction.

    @sophiecentaur, Thank you once again for replying! After reading your post, I looked into gas lasers a bit, and after seeing how easy it is to build say a "helium-neon laser," compared to getting all the right materials for the SS laser, I have decided to build a gas laser instead :biggrin: . What really made me want to build an SS laser in the first place was actually your first link, which stated that building an SS laser is the most simplistic in terms of designs, and I remember also reading somewhere in it that in order to build gas/ other lasers, that is where you actually needed all that high tech stuff like transformers, etc. Anyway, glad I could figure out that misconception in my mind.

    I still have some questions though. When you suggested to build a gas discharge tube, isn't that exactly like a "build yourself flash-pump" except with a different gas other than xenon, and also that your medium gain is the gas itself? or am I wrong on that one? Also, in terms of high voltage, do you think a USA standard outlet would be enough to supply that, or would a transformer be needed? Last but not least, you suggested the use of a vacuum pump; what exactly is that for? Is it so that the gas does not escape or to put the gas into the container in the first place? And, in terms of a gas laser, I assume that a vacuum pump is not needed, or no?

    Thank you again for your reply,
    - Curious_Dude
     
  8. Jun 6, 2012 #7

    sophiecentaur

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    Discharge tubes work under very low gas pressure. Unless you buy pre-filled tubes you need a pump. Any tube you do use needs good, optically flat ends but all that stuff must be available on the DIY market. You should join a specialist group. They will have sorted out all the wrinkles and will know just what can and can't be done. There's no point in re-inventing the wheel in these matters. You needn't worry that it will be all 'too easy'. It won't be!
     
  9. Jun 6, 2012 #8
    Hello again sophiecentaur!

    Thank you for the information! Only one problem... I tried searching around on the DIY market, but all the sites even remotely close to that name that sold laser parts did not have reflective mirrors, nor any of the parts I needed to build the gas laser I'm thinking of. And I have no idea where to find a specialist group. If you are referring to a specific site, could you perhaps link it?

    Thank you once again,
    - Curious_Dude

    PS: Still need answers on some of the questions in my previous post (wonder if anyone could answer them). Thanks.
     
  10. Jun 7, 2012 #9

    sophiecentaur

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    What is your general experience of building things and getting them to work? I think you can see from the fact that there is not a lot of laser building activity compared with amateur rado / hi fi / gadget construction that it is several orders of magnitude harder.
    I am wondering whether it is a realistic project for you and that something 'using' lasers would be more suitable and likely to succeed. Let's face it, there are lots of interference and diffraction experiments that you could do with a cheap as chips laser from ebay.
    Seriously, it may be the sensible solution to 'getting into' lasers. I don't want to be a wet blanket but I may be talking sense here.
     
  11. Jun 7, 2012 #10
    Alright... I see your point. Maybe I'll focus my mind on a different project... Thanks. At least I learned some stuff.

    Thanks once again,
    - Curious_Dude
     
  12. Jun 20, 2012 #11
    If I may suggest the following website regarding a simple TEA N2 laser - it looks relatively simple to make. I am unsure as to what materials you have access to, nor your familiarity with the electronics required to build such a device. Csele does a pretty good job of describing everything that is involved with this type of TEA N2 laser though, and google is a good friend when you hit a road block.

    http://192.197.62.35/staff/mcsele/lasers/LasersTEA.htm

    As always, be careful when working with lasers. A professor of mine was on the receiving end of a single (albeit high powered) ns pulse which resulted in a blind left eye. He was aligning the laser while a colleague of his (who had no idea where he was) decided to fire the laser to test something. This was in the 1970's, in Moscow I believe.

    Best of luck!
     
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