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Thread: To the laser show software companies

  1. #261
    Join Date
    Nov 2011
    Posts
    32

    Default Simple blanking

    First of all, Happy New Year to everyone ! Good Health and good mood !

    Please find attached a very simple blanking method we have proposed to a company doing copper vapor lasers (looooong time ago ! Anyone remember Spectronica ?)

    The beam first hits the scanner mirror next to the shaft, then goes to the adjustable ''return'' mirror. We only have to adjust this mirror so the reflected beam hits the scanner mirror at the other edge. Then the beam goes back to the ''return'' mirror and leaves the setup with the same orientation it entered it.

    In this setup, there is no need to re-glue the scanner mirror vertically, so the speed is not affected. By placing the ''return'' mirror approx 10cm away, you get a fast blank that can easily follow X and Y and needs only a small signal to blank the beam (around 1 volt)

    This is not a '100% perfect' blanking method as it slightly swifts the beam (very little though), but it has worked nicely in most applications, even graphics.

    A benefit is that the scanner mirror is hit at near zero degrees, so a 8mm wide mirror (for example) will accept an 8mm beam.

    (Optionally, the adjustable mirror for returning the beam to the scanner can be placed directly under the scanner, on the baseplate facing up. By doing this, the exit beam goes backwards towards the source).

    Enjoy responsibly !

    All the best to all !


    Tom Kamaras
    EyeMagicClick image for larger version. 

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  2. #262
    Join Date
    Feb 2011
    Location
    New Hampshire
    Posts
    3,513

    Default

    Tom,

    Staying with one scanner, what about a stop? Placing an aperture at @ a focus within the beam would prevent beam wander during blanking? With a longer FL lens pair I'll bet analog control would work as well.

  3. #263
    Join Date
    Nov 2011
    Posts
    32

    Default

    Quote Originally Posted by planters View Post
    Tom,

    Staying with one scanner, what about a stop? Placing an aperture at @ a focus within the beam would prevent beam wander during blanking? With a longer FL lens pair I'll bet analog control would work as well.
    Hello Planters,

    If beam movement is unacceptable, then possibly the only way way to go is to use a lens pair and flag blank around the focal point, as you suggested. You do not need to use long FL pairs, just go a little outside the focal point (where the beam is -for example- 0,5mm or so). Analog control works nicely in this method. You should also avoid the focal point for power density reasons...
    For the flag, you can use a (very good...!) mirror or a polished aluminum piece.

    Regards,

    Tom Kamaras
    EyeMagicClick image for larger version. 

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  4. #264
    Join Date
    Feb 2011
    Location
    New Hampshire
    Posts
    3,513

    Default

    Tom,

    I understand. I use common stainless razor blades in my spatial filters and for diode based lasers up yo 25W and 75mm FL lenses these work very well with no heat distortion and the retro-reflections are nicely diffuse. And they are VERY inexpensive.

    One advantage that I can see with lenses would be to demagnify the beam several fold while it passes through the blanking mechanism. This both reduces the required mirror size (increases the speed) and amplifies the motion across the mirrors (increases the speed). Extremely high speeds will greatly reduce the brightness of the tails.

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