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Are there commercially bought materials to make a laser?

  1. Feb 5, 2009 #1
    How do lasers work? Are there comercially bought materials to make a laser? What is the minimum wattage for a steel cutting laser? And does anyone know some cool experiments to do with lasers???

    Thanks in advance.
     
  2. jcsd
  3. Feb 5, 2009 #2

    mgb_phys

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    Re: Lasers???

    How much physics do you know ? Start here http://science.howstuffworks.com/laser.htm


    Shouldn't be too hard to make a he-ne laser yourself.

    >100W too big to really want to play with yourself.

    Amusing cats?

    https://www.youtube.com/watch?v=uxJvyzwQipw
     
  4. Feb 6, 2009 #3
    Re: Lasers???

    Hmm, cool is a very subjective term. Lasers are massively inefficient so any 'wow' stuff like damaging things is not really possible at home. For 'at home' type experiments probably the best thing lasers do is let you measure very small distances by setting up an interferometer.

    It depends what you consider cool though...
     
  5. Feb 6, 2009 #4
    Re: Lasers???

    You can buy one of http://www.ledshoppe.com/Product/ledp/LP1076.htm" [Broken] green 50mw lasers. You can see them in the dark, it's really cool.
     
    Last edited by a moderator: May 4, 2017
  6. Feb 6, 2009 #5
    Re: Lasers???

    Actually diode lasers are incredibly efficient and can put out enough power to destroy things. Diode efficiency is up to 65% i think the last time i looked. Flashlamp pumped solid state lasers are usually below 1% overall efficiency.

    You can get a diode laser for relatively cheaply and build your own control circuit to go with it. Fun little project really.
     
  7. Feb 6, 2009 #6

    Nabeshin

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    Re: Lasers???

    As far as I know, the most you can do with a purchased laser is pop balloons from a distance (this should give you an idea of the kind of power put out). Anything stronger than that is regulated by the government. (again, I think)
     
  8. Feb 6, 2009 #7

    Mk

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    Re: Lasers???

    Maybe you'd like this :wink:
    http://www.i-hacked.com/content/view/272/1/ [Broken]
     
    Last edited by a moderator: May 4, 2017
  9. Feb 6, 2009 #8
    Re: Lasers???

    I know a teacher who demonstates the use of a laser to transmit sound. He has a radio playing music through an external speaker. A small mirror has been glued to the paper diaphragm of the speaker. A laser sits on the workbench and is aimed at the mirror. The reflected ray goes across the room and is incident on a small panel of photovoltaic cells that sits on a different workbench. The wires from the photovoltaic panel are connected to the input of an audio amplifier. The output of the amplifier is connected to another speaker. Result: the sound coming out of the second speaker is a distorted copy of the sound coming out of the first speaker.
     
  10. Feb 7, 2009 #9

    Mk

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    Re: Lasers???

    Very cool, does anybody have any info on building laser microphones?
     
  11. Feb 7, 2009 #10
    Re: Lasers???

    A laser mic would be pretty cool.

    For designs - google is your friend: http://www.williamson-labs.com/laser-mic.htm

    EDIT: If you make lasers that are powerful enough to injure people (One that can pop a balloon will have the same effect on your eye!) I'm pretty sure you can be held accountable if you don't adhere to the quality documents that regulate the manufacture of lasers. Generally they'll need to be labelled and need a key to turn them on - but I'd suggest not going down that route. The full quality document is probably 100 pages +!
     
  12. Feb 7, 2009 #11
    Re: Lasers???

    Is it probable that damage-lasers will become part of regular warfare in the future? Or do they require too much power for low amounts of damage compared to bombs, grenades and projectile weapons?
     
  13. Feb 7, 2009 #12
    Re: Lasers???

    As open minded as I like to be, lasers are not going to offer any improvement in terms of someone walking round with one anytime soon.

    You can't simply point a laser at something and have it slice through it like it does in the films. The laser heats the object and a jet of gas blows the material out the way. You can't have long range, precise jets of gas. Pointing even a huge industrial laser at a human would just burn their skin; that'd be against the conventions for weapons production. A more realistic use would be to shine a bright green laser in their eyes to temporarily blind them. Again, if you do actually blind them, that's against the conventions.

    Laser are generally not efficient, some of them produce a percent or so of output for their input. The beam could easily be deflected with mirrors or absorbed by moisture & debris in the air. Setting fire to things, releasing smoke would soak it up.

    About the only serious use for them at the moment is shooting big projectiles out the air. Although, you're back with issues like targeting and absorption. The equipment is also power hungry and significantly more delicate than a standard weapon.

    These apply for a great number of the weapons the government is presently wasting your money on via research grants. Anything that requires electricity to power it is probably going to be a waste of time for now.

    Batteries store power ionically, they are at a massive energy disadvantage in regards to the chemical storage of an explosive. There are big losses in conduction and conversion to kenetics and you need special equipment to generate it. Explosives in bullets can be made in bulk, cheaply, they work simply and producing kenetic energy is basically their nature; they don't need taming into it.

    Furthermore, it's okay to splatter holes through people or blow them to bits, and it's easy to produce a huge amount of power to do that by putting the explosive in a casing. A shiny surface or smoke will not absorb a bullet.

    The most lasers that currently work in a military sense also use a chemical reaction to generate the beam, not electrical discharge. The reaction requires special equipment, quite a lot of careful handling and reactants.

    So no, nothing electronic is going to realistically replace good old bullets and bombs for a long time.

    A bullet is cheap, easy to make and works perfectly well in virtually every circumstance.

    The only time high tech, star trek style weapons will appear is when they have nuclear or anti-matter batteries in them. That's the only way you'll keep up with explosives in terms of output. I am sure that the government is presently working on some form of weapon based on this, an anti-matter bomb for example. They will have spent a lot of money designing some facility, somewhere in an attempt to optimize anti-matter production for this purpose. It's the next atomic bomb, only with a lot of additional possibilities.

    The future of weapons is automation, fuzzy logic and swarm intelligence. This is currently under the guise of intelligence gathering. We'll wait and see how that works out. Detachment from murder. Personally, I have a very bad feeling about where we could go with this solider saving technology.

    The CIA and other people have used laser microphones. They're not quite as simple as bouncing the beam off a window, they use interference patterns.

    They're generally quite complex and, with the advent of double and triple glazing, probably significantly harder to use or even make function.

    The wattage depends on how rapidly the energy is lost from the steel and how quickly you want to cut it.

    In general, a laser table will be at least 1kW. The faster, more expensive ones can be multiples of that. And they use about ten times more in electricity. With the table costing about a quarter to half a million dollars to buy and then pouring through the juice, they're not a cheap thing to get setup or run. Adding on the cost of replacement optics and gas for the nozzle is also something to think about, as well as tube servicing and replacement.

    Once you have a few kW, the thickness doesn't really matter. The operator will usually change the nozzle to one with a different focal length and run the program slower.

    Cutting anything other than sheet on a laser is generally a very, very bad idea in terms of cost.

    A flame table will cut through ten or more inches of steel quickly and cheaply. The result can be put through a mill if it needs to be precise. It'll come out more accurate than the laser will manage. You could probably buy the flame table and mill for less than the laser, and produce a more accurate result quicker and cheaper. Plasma is another option, although not as good as flame for work over an inch or so.

    Similar rules apply to waterjets as to lasers. Jets are much better in terms of cutting strange materials. Like ceramics.

    To make a laser table realistically affordable, you need to have it running 24/7 doing jobs for a whole bunch of people. The present economic environment means manufacturing is being hit hard anyway. The slightest error in tuning a manufacturing process, unnecessarily using a laser for example, will wipe out the profit margin and your business.

    Punch pressing is also a big competitor for laser cutting sheet.

    You can DIY a lot of gas lasers. Look at Sams Laser FAQ (google it). It has just about everything you'll find on the net about DIY lasers. You'll never produce something worthy of commercial cutting of steel at home, but you can make a bunch of colorful lasers that would be fun if you're into bright LEDs and lights.
     
    Last edited: Feb 7, 2009
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