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Galvanometer help

  1. Dec 1, 2006 #1

    taylaron

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    hey all,
    ill start you off with what im trying to make here... im tryting to make a galvanometer.. 2D.
    im trying to make a galvanometer so i can bounce a laser off a mirror mounted on it. then use the mirror to create laser patterns.
    first of all, does anybody know where i can buy a cheap one?not some ancient one......(there all over the internet)
    im trying to make it simple by finding one that can move in 2 dimensions. up down, and sideways.


    my orignal plan was to use a speaker and mount a mirror on it. (not those crappy kind that you just stick a piece of tin foil on the cone and "let her rip"
    i've made a series of designs incuding mounting a wire used in model airplanes for the rudders. then sticking one end of the wire on the cone, then the other on the middle of one side of a hunk of square aluminum that is being supported by a piece of fuel line tubing fromt the local hobby shop. then do the same process with another speaker but for the other side of the aluminum. mount a small mirror in the middle of the piece of aluminum and shine a laser on the mirror. after i supposedly get this to work i would create a program to write the complex sound files for the speakers to move the mirror in 2D in a defined pattern.
    one problem is that the speakers have a degree of inaccuracy and anything i build that is mechanical (brass parts, etc.....) there is some inaccuracy in the movement of the parts.

    another thing i tried was to mount a brass bar across the top of a speaker (in front of the cone) and then mount one side of the mirror to the cone and the other make it pivot on a stationary point.:surprised .....aaah just look at the picture....


    does anybody know of this trying to be done before?
    input anybody?
    i'd very much appreciate you advice and or help on this matter.:cry:
     

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    Last edited: Dec 1, 2006
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  3. Dec 2, 2006 #2

    NoTime

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    It's been a while since I did any work with this.
    The general solution I've seen is to use two mirrors.
    1 for vertical motion and 1 for horizontal.

    Using voice coil drivers is not a bad approach, but it might help to use small cheap speakers and remove the cone part.
     
  4. Dec 2, 2006 #3

    taylaron

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    great suggestion. i never though of actually removing the cone. pretty dangerous to the coil's integrity though i would think.
    whats this about voice coil for drivers?
    i understand the concept of the coil in a speaker, but are you saying removing the coil and use the coil??

    would it work to cut off the "cone" in the center and place a light weight mirror there?-before i go taking a rasor to my poor speakers...

    but do you know of anybody using speakers for the drivers of the 2 mirrors?
     
    Last edited: Dec 2, 2006
  5. Dec 4, 2006 #4

    taylaron

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    Help Somebody!!!!!!!!
     
  6. Dec 6, 2006 #5

    NoTime

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    I was thinking of using the coil as a linear motor.
    Yes, you coluld destroy a few speakers easy enough and if you do this you may need need to add a guide to keep the coil from tilting and rubbing. Mostly it takes a lot of power to move the cone and depending on how you want to move the mirror the sound could be rude.
    The general idea is to tilt the mirror. One edge is a hinge the opposit edge is connected to the coil.

    A spherical mirror could work.

    Normally it would be linear drive (with or without feedback).
    This is basicly a voice coil.
    Rotating polygon mirrors like the one in a laser printer are also used.

    Edit: This has ome info
    http://www.cambridgetechnology.com/news/Choosing_A_Galvanometer.html
     
    Last edited: Dec 6, 2006
  7. Dec 6, 2006 #6

    taylaron

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    cool,
    but would spherical mirror work for what im trying to accomplish? -hence the first post-

    -im trying to get around spending a couple grand on some cambridge galvonometers here............ whither its worth it or not......
     
  8. Dec 7, 2006 #7

    NoTime

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    If you have specific performance requirements that's an entirely different matter.
    You haven't said what they are.
    Just that you wanted to make patterns.
    You could only use a spherical mirror for one of the mirrors.
     
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