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Thread: Arduino controlled ILDA for animated projection - Help wanted -

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    Default Arduino controlled ILDA for animated projection - Help wanted -

    Hi All,

    I am new to this forum and admittedly am not a laser expert. Want to get a projector built for a proof of concept demonstration and I don't know how or where to start. The laser projector should produce animated projection based signals from a micro controller. Any dvise would be much appreciated or PM if you want to work on this project. Cheers!

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    A Raspberry Pi 4 and a modified USB sound device is a much more capable solution.
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    Quote Originally Posted by james View Post
    A Raspberry Pi 4 and a modified USB sound device is a much more capable solution.

    Did you compile LB for the pi?
    leading in trailing technology

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    Yes. It works very well.

    Since it uses libSDL 1.2, it can work with the Linux frame buffer. So you don't even need X. You can run it from the native command prompt.
    Creator of LaserBoy!
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  5. #5
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    The minimum to make your project worthwhile and compatible with good vector graphics is that every 3.333 x 10^-6 seconds or so, you have to dump out, at a minimum, the following:


    • Ten bits resolution or greater of X axis position, converted to a bipolar analog signal
    • Ten bits resolution or greater of Y axis position, converted to a bipolar analog signal
    • Eight bits of red color data converted to an analog signal, 0 to 5 volts
    • Eight bits of Green color data converted to an analog signal, 0 to 5 volts
    • Eight bits of blue data converted to an analog signal, 0 to 5 volts
    • Galvanometer scanners do not do well with PWM as the reconstruction filter needed phase shifts the signal distorting the images. So you need DAC chips and the associated interface timing and memory. DACs take time to load. This hardware requirement and the tight timing rapidly takes you away from Arduino and "Processing".
    • You need the X, Y, and color DACs to update at the same time, known as "Double Buffering", or you can see a fluctuating skew at the corners of an image.
    • Without some way to sync the show output to music or without having at least 60 keypresses to link effects to, or without something like scripting or OSC, your life will be miserable.
      • ~
        ~
      • 1 over KPPS = minimum update rate for the DAC, so for 30 KPPS point update rate, that is 1 divided by 30,000 for the point update rate in seconds. So your processor needs to output a minimum of five streaming waveforms, The response of angle vs time for the galvos that deflect the beam is non-linear, and so we tune the galvos to an industry standard test pattern, the result of this you need an output with a bandwidth about 7-10 times that of the galvos themselves. the galvos act as a sort of complex low pass filter or integrator with a resonance (or two or three or more) and have a bandwidth that changes (real big simplification of the actual physics) with the deflection angle of the previous jump and the angle of the next one. . So at eight degrees deflection and the standard test pattern the galvos have a response (small angle) of about DC to 2400 Hz. But we feed them the updates at roughly ten times that, so 30,000 updates per second is often needed. So five DC to Audio waveforms need to be streamed out of your controller.

    • A typical frame of an animation contains anywhere from 10 to 1100 points. That means you need access to a LOT of RAM or other storage to put on a decent show.
      • Steve
    Last edited by mixedgas; 05-04-2020 at 18:35.
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    Like I said: A Raspberry Pi 4 with a modified USB sound device works very well. It actually works well on a RPi 2, but a 4 is even better. If you get a USB SND8 sound device you have 8 channels. So you have the 5 you need for laser control signals and you still have room for left and right audio all at 16 bit 48KHz. You can play 8 channel waves. I know it works. I have done it.

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    Last edited by james; 05-04-2020 at 19:25.
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    All software has a learning curve usually proportional to its capabilities and unique features. Pointing with a mouse is in no way easier than tapping a key.

  7. #7
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    There is also:

    https://www.ether-dream.com/

    Talks to anything, Mac, Linux, Windows..
    Can play off an SD card.


    And if you can link to a PC...

    https://github.com/cfavreau/Laser-Show-Shield

    I have one of the Show Shields, but the timing is really, really, tight and the color resolution is three bits.

    And if you can link to a PC:

    http://aldebaran-systems.com/WaveUSB.htm

    Steve
    Last edited by mixedgas; 05-05-2020 at 06:56.
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    Creator of LaserBoy!
    LaserBoy is free and runs in Windows, MacOS and Linux (including Raspberry Pi!).
    Download LaserBoy!
    YouTube Tutorials
    Ask me about my LaserBoy Correction Amp Kit for sale!
    All software has a learning curve usually proportional to its capabilities and unique features. Pointing with a mouse is in no way easier than tapping a key.

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    some time ago I saw this,
    maybe you may be interested


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    Quote Originally Posted by haze View Post
    some time ago I saw this,
    maybe you may be interested

    That's pretty close to how AndyCon and I started with the boomdog boxes. Both of us stayed entertained with that about a week and that's what lead both of us to this forum and real equipment.

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