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Thread: Propagating Rainbow Effect?

  1. #1
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    Default Propagating Rainbow Effect?

    I remember reading about a laser light show effect that, if I remember correctly, produced a beam that looked like different colors chasing each other away from the source. Like a propagating rainbow. I recall it might be simply the result of proper timing of modulated R G & B beams before combining them. Is this a commonly used effect?

  2. #2
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    Hi Robert

    It is by me!

    A few of my analogue controllers have colour sequencing due to their colour keyboard scanning technique. This allows a selection of colours to be locked into memory and then sequenced with a variable clock speed. If this is used with the figure generator running through an x/y sample and hold board (with its own variable clock) which I call a "Digitizer" you end up with a colour chase superimposed on a figure section which chases round whatever lissajous figure you have set up.

    (This can be just a straight line but that's boring).

    The effect is similar to a tape being waved around in the air but with the colours chasing along the tape trail.

    Obviously best after a few beers

    Colour is the English word for that which our transatlantic cousins call color!

    Confusing isn't it!


    Cheers

  3. #3
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    So you're saying that for the straight line case (no x-y scanning), and say through a good fog, a viewer from the side will see colors chasing each other along the beam? Can they be stopped, or run backward toward the source?

  4. #4
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    Default analog controller

    hi
    i would like to know more about your analog controller please , do you have a link to where i can read more on it ??
    cheers
    chris

    Quote Originally Posted by catalanjo View Post
    Hi Robert

    It is by me!

    A few of my analogue controllers have colour sequencing due to their colour keyboard scanning technique. This allows a selection of colours to be locked into memory and then sequenced with a variable clock speed. If this is used with the figure generator running through an x/y sample and hold board (with its own variable clock) which I call a "Digitizer" you end up with a colour chase superimposed on a figure section which chases round whatever lissajous figure you have set up.

    (This can be just a straight line but that's boring).

    The effect is similar to a tape being waved around in the air but with the colours chasing along the tape trail.

    Obviously best after a few beers

    Colour is the English word for that which our transatlantic cousins call color!

    Confusing isn't it!


    Cheers

  5. #5
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    I nearly replied to this earlier but didn't as I couldn't decide exactly what effect you were looking for.

    I think (depending on the speed you require) its possible to create this in Quickshow or LivePro by using the colour slider on auto:

    If you click on the ->| symbol at the opposite end to where the slider is currently (indcated in the picture below by the green arrows), then the slider will slide itself through one end of the spectrum to the other at a constant rate. If you click at the other end, you can send it immediately back through the spectrum.







    Video Clip - you have to remember you're seeing the front edge of the beam here and not the actual beams themselves:

    Last edited by White-Light; 08-15-2010 at 03:13.

  6. #6
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    That looks like control for the color of the output beam from an RGB projector. I'm looking for a single beam that was red for a distance (say 1M), green for a similar distance, then blue for a similar distance. The colors repeat the pattern and move along the beam slowly, at a perceptible speed so it looks like the colors are chasing each other along the beam. I remember illustrations showing a sawtoothed chopping blade (the article I recall was in the very early '80s), so I believe this to be a simple chopping technique.

  7. #7
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    Quote Originally Posted by robert hess View Post
    So you're saying that for the straight line case (no x-y scanning), and say through a good fog, a viewer from the side will see colors chasing each other along the beam? Can they be stopped, or run backward toward the source?

    Oh lord! I think I have been confusing things again!

    The example I gave doesn't have colours tracking "along the beam" they track along the beam trajectory. The only time I have ever managed to track along the beam was about thirty five years ago. I was installing in a disco with such low ceilings that I had beams running through glass tubes fixed to the ceilings. After going to such expense I decided to connect the "input" ends of these tubes through plastic pipes to a large box with a tiny fogger , a butterfly valve and a sub-woofer. The music base beat sent puffs of smoke down the glass distribution tubes and gave an "along the beam effect". This was too early on for me to be using colours however and I just sync strobed the argon blue/green mix to get the travel speed to look fast.

    Sorry but this is not quite what you are looking for I think!

    Given the speed of light getting colours to travel "along" the beam sounds like a very tall order since it requires the colours to end somewhere along the beams trajectory or at least to metamorphosize into a different colour interferometrically.

    Tough one that!
    Sorry

  8. #8
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    Quote Originally Posted by badger1666 View Post
    hi
    i would like to know more about your analog controller please , do you have a link to where i can read more on it ??
    cheers
    chris
    Hi Chris,
    Sorry mate, they are all hand built and each time I build they evolve.
    I have been boring the pants off lots of people in this forum already with my weird antiquated ideas. Shoot me a PM with specific questions and I will try to answer them as best I can.

    Cheers

  9. #9
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    Quote Originally Posted by robert hess View Post
    That looks like control for the color of the output beam from an RGB projector. I'm looking for a single beam that was red for a distance (say 1M), green for a similar distance, then blue for a similar distance. The colors repeat the pattern and move along the beam slowly, at a perceptible speed so it looks like the colors are chasing each other along the beam. I remember illustrations showing a sawtoothed chopping blade (the article I recall was in the very early '80s), so I believe this to be a simple chopping technique.
    Ah sorry Robert I know what you mean now.

    I think I can think how it can be done but it means building and colouring the frames yourself from a frame editor unless you know someone who already has such a file. I'm thinking fan effect if you had the chopper effect abut it could just be a single beam scanned quickly side to side and the camera shutter effect.

  10. #10
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    I think I know of a pill that'll give you the desired effect - only problem is you need enough for a room full of people!

    Otherwise I can't see how you would possibly achieve that with coherent light - although I'd love someone to show me otherwise! (without the pills)

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