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Thread: Beam Director

  1. #1
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    Default Beam Director

    I need to steer a large diameter beam (50mm in diameter) with remote (computer controlled) input. The speed is REALLY SLOW. The beam is pulsed at up to a maximum of 4 PPS and the pulse is essentially instantaneous and so nearly 250msec are available for the mirror(s) to slew and settle.

    I originally thought a pair of big mirrors on two of the Pangolin Vrad motors would work, but these mirrors have to be really huge and the controller will also need an amplifier to drive the motors. What about adapting the moving head mount on a Gobo? With the light removed and a single mirror around 150mm square the X and Y can be handled by a single mirror and the control for these already exists as part of their standard operation. How rapidly can these be aimed? Would there be a best choice for my application? If they loose a signal or power do they go nuts or can they remain steady or move to a "safe" mode?

  2. #2
    swamidog's Avatar
    swamidog is offline Jr. Woodchuckington Janitor III, Esq.
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    what about something like this?

    http://www.zaber.com/products/produc...M&tab=Features


    Quote Originally Posted by planters View Post
    I need to steer a large diameter beam (50mm in diameter) with remote (computer controlled) input. The speed is REALLY SLOW. The beam is pulsed at up to a maximum of 4 PPS and the pulse is essentially instantaneous and so nearly 250msec are available for the mirror(s) to slew and settle.

    I originally thought a pair of big mirrors on two of the Pangolin Vrad motors would work, but these mirrors have to be really huge and the controller will also need an amplifier to drive the motors. What about adapting the moving head mount on a Gobo? With the light removed and a single mirror around 150mm square the X and Y can be handled by a single mirror and the control for these already exists as part of their standard operation. How rapidly can these be aimed? Would there be a best choice for my application? If they loose a signal or power do they go nuts or can they remain steady or move to a "safe" mode?
    suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.

  3. #3
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    I don't think this will do it. If the beam is striking the mirror at a 45 degree angle, the optic will need to be a minimum of 3 inches in diameter and the beam may need to be directed such that the foreshortening will require as much as 5 inches. Also, the extreme resolution implies that the max speed is slow. I am hoping to get say 100 degrees/ second or better between pulses. The range at 20 degrees optical is not too bad.

  4. #4
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    is this for lab or light show?
    Stepper motors?
    would u b interested in a older big galvo w/ paddle mirror? there is some older stuff like for fiber fed heads for YAG

  5. #5
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    is this for lab or light show?
    Neither, really. I am trying to steer a pulsed laser to track and then target moving objects (inanimate!). I don't know how big the paddle mirrors get, but other than big industrial galvos, I suspect nearly 80mm minor axis would be very rare. The only reason I don't think this project is crazy hard is the very slow speed for repositioning. Stepper motors are a good idea if micro-stepping resolution is available. The precision jitter error of these micro-steps is acceptable. The reason the moving head is interesting me is that the Y mirror in a mirror pair becomes tremendous. For a clear aperture without vignetting the Y has to be at least 3 times as long as the 50mm beam is wide!

  6. #6
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    a small turret would work too i guess then. or a mirror on a yoke. how accurate r u trying to get? with OpenCV or Openframeworks, an arduino and microstepping drivers you could pull it off affordably.
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  7. #7
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    have you looked into hobby servos? Very easy to control.

  8. #8
    mixedgas's Avatar
    mixedgas is online now Creaky Old Award Winning Bastard Technologist
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    I have some 3" diameter 45' directors on ball bearing bases designed to be turned. I'll take a pic when I get home. I have a LOT of them.

    Steve
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  9. #9
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    I got a neat suggestion from an interesting source.

    http://www.hobbyking.com/hobbyking/s...ontroller.html

    For those with drone experience this might not be the best choice, but in general these gimbals seem to be a really good solution. They slew to 2000 degrees/ second, are made to move weights similar to a good quality (thick) 150mm square mirror and they are inexpensive. They need to interface with a computer and the dongle suggests this one does.

  10. #10
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    RGB laser projectors
    Pangolin Beyond .NET
    APC40 Midi controllers
    Pangolin FB3 controllers
    DZ splitter
    LS MegaWatt Green Machine

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