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Thread: RGB System. White beam sometimes white, sometimes pink...

  1. #1
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    Default RGB System. White beam sometimes white, sometimes pink...

    Hi all,

    I have my first RGB projector up and working really well.
    DT40 Pro Scan Set
    Pangolin QS and FB3
    LaserWave 640nm @ 300mw
    DHOM 532nm @ 300mw
    DHOM 445 @ 600mw

    The only issue I have is that in certain cases the white is not really white. It flickers between pink and white, but seems to be related to the size of the object. Small objects with white lines are drawn white, while large objects tend to have the white lines pink. Sometimes the pink lines flicker between true white and pink... If I draw a test object in white and plop it on the timeline, then change the properties so the image scales from 0 to 100 % over time, then I drag the timeline cursor to view the behavior of the object the following happens. As the object grows in size it reaches a point where it goes from true white to a flickering pink. I have been all through the color balance min and max settings under projector settings and these have no effect on this issue.

    Any ideas?

    Thanks

    Rob

  2. #2
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    Sound like your green is having a modulation issue oe jelybeaning. It might be poor liniear modulation, an issue with the green not being warmed up, or a TEC problem. It may be the way the color balance is set up in your software or how lineiar the DAC's modulation curve is. It is defiantly your green, green plus magenta equals white; if your green drops a little you will get pink.
    Love, peace, and grease,

    allthat... aka: aaron@pangolin

  3. #3
    Bradfo69's Avatar
    Bradfo69 is offline Pending BST Forum Purchases: $47,127,283.53
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    That would explain what I've been running into with the projector I purchased from Smogthemog. I have similar issues with white and pink and we KNOW the 1 watt Viasho 532 needs a little attention. Rob Stanley had to work on it in a hurry before it was shipped to me and, didn't have enough time to get it back to 1 watt after replacing the IR diode. Apparently they're a bit tedious to align correctly. It's running at about 450mw right now and after SELEM, I think it's going to go visit OSLS for a tuneup.

  4. #4
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    Yep, basically poor modulation for the green. I've had this on all but one of my greens, and I've now found the solution is just to get a bigger green than is needed. That said, I have one LW green that is just excellent under modulation, all the others have been 'less good' but probably typical of most DPSS greens.
    Frikkin Lasers
    http://www.frikkinlasers.co.uk

    You are using Bonetti's defense against me, ah?

    I thought it fitting, considering the rocky terrain.

  5. #5
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    Hmmmm.

    Wonder why only the green has the issue? The red and blue seem rock solid, and the blue is the same manufacturer...
    The green does flicker a lot so that is definitely the issue...

  6. #6
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    In short,
    Because green is the only color that relies on shg to produce its light. The crystal that converts infrared into green light is very sensitive to temperature fluctuations.
    The other colours don't really care about their thermal management, as long as they don't get too hot.

  7. #7
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    Wonder why only the green has the issue?
    Because the green is the only DPSS laser of the bunch. The 640 and 445 are diode lasers which can be modulated reliably on their own. DPSS lasers are notoriously bad for modulating which is why peopple wanting to do it properly use an AOM, or spend a lot of money on the head.

    Pays yer money, takes yer choice
    Frikkin Lasers
    http://www.frikkinlasers.co.uk

    You are using Bonetti's defense against me, ah?

    I thought it fitting, considering the rocky terrain.

  8. #8
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    Guys,

    Thanks for the answers... So where does this leave me? Seems as though this DHOM 300mw Green is destined for chasing the cat instead of being a part of my projector... What 300 to 500mw DPSS Green laser would you guys recommend that does not suffer from these problems?

    Rob

  9. #9
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    They all do to a certain extent - based on my experience of Chinese lasers.
    Not sure about any of the offerings from Kvant etc, as they are quite a lot more expensive.
    Frikkin Lasers
    http://www.frikkinlasers.co.uk

    You are using Bonetti's defense against me, ah?

    I thought it fitting, considering the rocky terrain.

  10. #10
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    Some time ago kvant launched a "new" model with a pretty impressive modulation response.

    HERE!

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