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Thread: turning blanking off on Livepro

  1. #11
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    Hi Jeremy;

    Glad you like the timer thingy... Though I really can't take credit for it. Randy (Stuka) is the one that found it.

    As for the power measurement idea - there are a couple different things he can do. If he can get into his projector easily, he could simply block off the beam from the other lasers. But that's cumbersome.

    He could also change the color to RGB rainbow cycle, and then take the color speed down to zero when the correct color is being displayed. He'd have to go up on the color speed and then back down to zero to select the next color.

    You're right in that any pure abstract will work, but the default waveform is a sine wave, so that's going to give you a circle. Note that this trick won't work unless you're outputting a constant abstract, however. (This leads me to believe that abstracts based on ILDA files won't work, and I know it won't work for regular ILDA files that aren't abstracts.)

    I remember Bill talking about how blanking is handled at one of the FLEM's, and he said that the only way to get an accurate power measurement is to create a circle in the abstract generator and reduce the size to zero. However, he may have been talking about the most obvious case, so it may be true that a square or triangle wave will give the same result.

    Adam

  2. #12
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    I find that changing the number of points for the abstract has an effect on the measured power from the laser using this kind of simple sine abstract. The maximum was around 400 points if i recall correctly.

    You change this value in the image properties.

  3. #13
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    Hmmm... That number of points thing must be a control for the LA Studio abstract generator. The LD-2000 abstract generator doesn't work that way, at least not for circles.

    Actually, if it uses points at all, then I'm not sure you'll get a valid reading with the LA Studio abstract. Bill explained that there is a blanking interval between each re-drawing of a point-based frame. With a pure abstract, however, the laser never gets turned off. But if LA Studio can't generate such an abstract, then that blanking interval will still be there and that will throw your power reading off a little.

    Adam

  4. #14
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    Well, with the FB3 there's always blanking, because the processor needs a short break between frames regardless of the software. LAStudio Abstract and the LivePRO Abstract generator are practically the same btw.

    I think I measured the maximum duty cycle to be around 85% with a simple sine abstract. It can go much lower though, so it is not a good way to measure the maximum CW power of the laser. Especially if it handles blanking poorly.

    It's taken me a while, but I'm really starting to see the technical advantages of the QM2000 now.
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  5. #15
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    why not just make up a simple circuit that allows you to dump 5v into each of the mod inputs of the ILDA connector on your laser ?

    this will give you full CW power, without an uncertainty, except though around how much you are losing off your mirrors...
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  6. #16
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    Quote Originally Posted by tocket View Post
    It's taken me a while, but I'm really starting to see the technical advantages of the QM2000 now.
    If you are running LivePRO on the QM, there isn't much difference.. The processor still needs a break with the QM..
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  7. #17
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    Cool

    Quote Originally Posted by dave View Post
    If you are running LivePRO on the QM, there isn't much difference.. The processor still needs a break with the QM..
    Does it need a break when displaying a circle using the abstract generator on the QM? I thought that was one case where it didn't?

    Adam

  8. #18
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    That's the solution I use...
    I made an op amp based gain & offset circuit, with a relay which, when activated, gives 5V instead of the dac voltage to all the lasers. It's great to warm up the laser without modulation so they can reach optimal temp and power.

    Better, the switch has a wireless remote So I can make the laser waming up before a show, even when it is not accessible... Of course, the circuit was made in a way that warm up mode is possible only if the shutter is closed.

    Quote Originally Posted by aijii View Post
    why not just make up a simple circuit that allows you to dump 5v into each of the mod inputs of the ILDA connector on your laser ?

    this will give you full CW power, without an uncertainty, except though around how much you are losing off your mirrors...

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