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Type of laser -- which is easiest to make?

  1. Dec 31, 2014 #1
    Hello,

    Which type of laser are easier to make ? Micro-wave (MASER), infrared, visible light, UV... ?
    Which type of light leads in an easier way to a population inversion ? Is it maser because the level energy involved are closed ?
    Thank you
     
  2. jcsd
  3. Dec 31, 2014 #2

    mfb

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    Easier in which context? With material you have at home, in a good lab, in a laser factory?
    Historically, the maser came first. The cheapest source for coherent light (visible and infrared) today should be laser diodes.
    UV is tricky.
     
  4. Dec 31, 2014 #3

    SteamKing

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    X-ray lasers are the worst. You need a strong source of X radiation, like what comes from a nuclear blast. This was a big stumbling block in building the SDI.
     
  5. Dec 31, 2014 #4

    mfb

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    Nuclear weapons don't work for laser emissions.
    Free-electron lasers can produce coherent x-rays - up to ~10 keV at SLAC, for example. The European XFEL should achieve even higher energies.
     
  6. Dec 31, 2014 #5

    SteamKing

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  7. Dec 31, 2014 #6

    mfb

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    Oh wow, nuclear weapons to pump an x-ray laser. I didn't expect that.
    Good to have more... non-destructive sources now.
     
  8. Jan 1, 2015 #7
    @mfb Just easier if we talk about the energy of the light involved. (not about the material, juste suppose that you have access to anything)
    Is it true to think that's MASER because of the proximity between the level involved ? If we look at the boltzmann distribution, ΔE is smaller with maser and it would be easier to obtain N2 > N1 ? Is that reasoning correct ?

    Thank you
     
  9. Jan 1, 2015 #8

    sophiecentaur

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    I don't what application the OP had in mind for a laser / maser but an optical EM generator is far easier to detect.
    I saw a demonstration of a laser which consisted of a block of Jelly ("Jello") and a Photo Flash but we had to take the guy's word that it was producing anything worth having. Nitrogen Lasers are easy to make, I believe but they produce ionising radiations and are not safe to use - bad idea, even if it could prove the point.

    It's down to what you mean by "easier". Not long ago the word "possible" would have been more appropriate until they developed a semiconductor industry. Now, semiconductor lasers are very 'easy' to produce - but probably not on your kitchen table.
     
  10. Jan 2, 2015 #9

    mfb

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    You need less energy per system to get a population inversion, but that is not an issue for lasers. Power comes from the wall plug.
     
  11. Jan 10, 2015 #10
    And, just to be sure, is it possible to avoid the reflection of some frequency during the wall plug ? To be able to have only the frequency of the laser transition and avoid transition from the ground state (to maintain the population inversion).
     
  12. Jan 10, 2015 #11

    mfb

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    I have no idea what you are asking in your last post.
    The laser operation has nothing to do with the power grid.
     
  13. Jan 10, 2015 #12
    Yes you're right, it's another thing. I just want to know if it is possible to avoid some reflection (in the gain medium) ? can we modulate the miroir to absorb (and so not reflect) some frequencies ?
     
  14. Jan 10, 2015 #13

    mfb

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    Which frequencies are you talking about?
    Different modes in the laser cavity? Mirrors won't be specific enough to differentiate between them, but you can add more cavity-like structures to suppress unwanted modes.
     
  15. Jan 11, 2015 #14
    If we consider a 3 level laser, we have to avoid absorption from level 1 to 2 (if it lase between 3 and 2). So, I'm asking if it is possible to not reflect the hν12 which is made by the spontaneous emission between this 2 level ?
     
  16. Jan 11, 2015 #15

    mfb

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    Sorry, I have no idea what you are asking.
     
  17. Jan 11, 2015 #16
    Hiltac, what are you starting with? What's your budget? What's your goal? How much time do you want to put into this? There are plenty of DIY laser instructions on the web. You can get a functionning red diode for less than a dollar, and you can ask gouvernments for billion dollar grants to gamble on something new. Solid, liquid, gas, or diode? That's a start.
     
  18. Jan 12, 2015 #17
    Helium neon gas lasers are simplest to make. The first polarized amplified beam of radiation was microwave a maser.
     
  19. Jan 12, 2015 #18
    I have put together several types, most need good glass skills, and a good vacuum system.
    I remember reading a Scientific American Article in the 70's about building a CO2 laser
    with a water aspirator, manometer, and wall voltage, very simple setup.
    I don't remember what they used for an output coupler.
    Be careful! 10.6 um can be very dangerous.
     
  20. Jan 12, 2015 #19
    I've seen the X-Ray beam from a CT scanner melt the table in diagnostic mode, sticky iris.
     
  21. Jan 12, 2015 #20
    Normally red lasers are the cheapest, you can get a mouse pointer for like nothing. Blue and Green cost more but require more power, at least they used to, today who knows.
     
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