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Thread: Beamshutter question

  1. #1
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    Default Beamshutter question

    I was thinking of making an beamshutter for my 1.7watt laser.
    I got an solenoid that I may use for it.
    BUT I was thinking of the reflection of the beam...it can damage the optics of the laser..
    Any ideas?? Maby add an dichros that pass green/reflect green at the front of the laserhead? Then the beamshutter after the dichros?

    Anyway, here is my setup. Just need to build an case


    Thinking of adding beamshutter in the square some place

    Pangolin FB3 QS/LivePro/SMS2Laser
    Riya MultiBus
    Pangolin LD2000 Pro

  2. #2
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
    Infinitus Excellentia Ion Laser Dominatus
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    The usuall route is black anodized metal flag made of a rough cut chunk of aluminum. Any black anodized AL should do it. The flag is NEVER perendicular to the beam if done right.

    Steve

  3. #3
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    Here is one om my beamshutters.

    There is 2 wires that requires 18-20V (got an PSU to drive this)

    But I need something to connect this to the ILDA pin 13. to activate the beamshutter..

    any ideas?
    Thanks
    Attached Thumbnails Attached Thumbnails beamshutter.jpg  


    Pangolin FB3 QS/LivePro/SMS2Laser
    Riya MultiBus
    Pangolin LD2000 Pro

  4. #4
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    The shutter should also be immediately after the emitter, not after subsequent optics, if it's also part of safety or legal requirements for use in a public place. Also, make sure the unpowered state is the blocked state. I'm not sure how strict that requirement is in Europe's mainland but if in doubt, do it. And I agree with Steve, black anodised aluminium is so good at conducting heat that it will safely block far stronger lasers. The one exception is UV which can bleach the pigment and raise reflectivity. I bought a sensor head that this had happened to, it looked really weird. Tried to spraypaint it black again but the paint wouldn't stick well.

    Some small heatsinks might make good flag shutters because they have a fine texture to raise surface area, and that can absorb more light, and will scatter what it reflects so well that it won't be critical how you align it.

    If the signal in pin 13 is positive at more than 3V or so, you could use a MOSFET (no other part required). Almost any might do this. Make sure you protect it with a diode against the collapse surge when disconnecting the solenoid.

  5. #5
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    Like Steve said, use a black anodized piece and make sure its not perpendicular to the beam. Something else to remember, it looks like you are using a Ledex solenoid. You will really want to pay close attention to the specifications of that model solenoid you have. If it says 18V, that may be at a certain duty cycle. On the spec sheet it should have voltage ranges for different duty cycles. Since you will want this to operate essentially for an infinite lenght of time, you might find that driving the solenoid with 5-8V would be more appropriate. If you tell me the model number I can look it up if you can't find it.

    The ledex solenoid works great as a shutter, but you might find that you would be much happier with something like a GM-20 since they make no noise.

  6. #6
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    Just a simple thought here...

    When using very high power lasers or anything in question at all we have made it our policy to use a 3mm (or 1mm) white light mirror glued (No 5 minute epoxy here just a bit of RTV will do it) to the end of a flag that is mounted to the shutter actuator. We then twist the flag to achieve about a 45 degree angle to then intercept the beam and at the same time fire it directly back down into the beam table. This will save your ever expensive shutter (GM20, MFE, or clone) from the heat that will absolutely be absorbed through the flag via the laser source your are currently blocking. Trust me we burned up many actuators in the past and this is by far the best method of intercepting a beam while at the same time not causing or adding too any heat issues that may occur with your expensive laser components.

    Again just a tidbit of info to keep more $$$ in your pockets rather than learning by doing which at times may and can end up being very pricey in the long run...

    Good luck on your build completion...


    OSLS

  7. #7
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    Hey Cruch,
    I used a solid state relay for my shutter control. It accepts less than 3.5 volts in at very low ma, and will switch on up to 32 volts DC @ 10amps on output side. Everything is Isolated. I bought mine from www.Grainger.com here is the part number, check it out:

    Part #5Z950

    Solid State Relay, Input DC, Maximum Input Voltage 32 VDC, Minimum Input Voltage 3.5 VDC, Output DC, Minimum Output Voltage 0 VDC DAYTON
    5Z950 1 Today $26.45 271

    http://www.grainger.com/Grainger/items/5Z950

    The only note is that you have to follow + and - on your circuit. But works great with my pangolin cards.

    I did try a coil relay, with no luck, it tried to draw to much current from card. And I forgot I am also using 2 ledex rotary solenoids for my shutters.

    and I agree of the use of the diode across the leads of the solenoid..

  8. #8
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    Quote Originally Posted by Misebeam View Post
    Solid State Relay, Input DC, Maximum Input Voltage 32 VDC, Minimum Input Voltage 3.5 VDC, Output DC, Minimum Output Voltage 0 VDC DAYTON
    5Z950 1 Today $26.45 271
    You can get fifty IRF630 MOSFETS on eBay for much less than that, each one of which will do that job. Gate capacitance is too high for a modulated laser driver but for moving mass they're great, they handle up to 9 amps through a resistance of 0.35 ohms, with a negligible current to control them which is only drawn during the charging of the gate capacitance. They even have protection diodes built in, though you might want to add an external one if you're driving a solenoid. They draw so little current from the controlling circuit that you'll want a resistor between its output and ground if the output doesn't sink as well as source, just to make sure a residual charge doesn't keep it switched on. This is NOT a problem with them, I'm just describing it to show how efficient they are.

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