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Thread: Why do I need to have a sealed optical cavity...?

  1. #1
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    Default Why do I need to have a sealed optical cavity...?

    Ever wondered why it is best to seal off your optics?

    Well, here's the answer... A picture of my RGB after being at a festival for a week... looks pretty grim, but the optics are sqeaky clean thanks to my perspex box around them...


    Click image for larger version. 

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    Mark

  2. #2
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    Exclamation

    Holy Crap!

    Where did you have that thing mounted? Out in the desert? In the middle of a sandstorm?

    What is all that crap? Surely it's not just dust?

    Adam

  3. #3
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    It was hanging off a truss in a huge tent... The dust is basically dry soil where so many people were dancing, the whole arena was just a cloud of dust... Kind of a natural hazer

    If you think that is bad, you should see the state of the laptop and control desks... Let alone the state of the DJ decks...

    Mark

  4. #4
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    Default

    Thats about par for the course for a dry festival really, even if you can't see the dust its amazing how much you find on kit at the end.

    Question, did you leave it powered throughout? I notice you use positive pressure fans with the open exhaust on top (and perhaps elsewhere) but if you switch it off, that all goes out the window, right?

  5. #5
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    Quote Originally Posted by norty303 View Post
    Thats about par for the course for a dry festival really, even if you can't see the dust its amazing how much you find on kit at the end.
    Spot on, I have done several festivals with various lasers and always end up the following week cleaning everything up :-)

    Really this post was a bit of fun and also to alert new builders as to why you need to keep your optics separate from the cooling systems... I have seen several builds with fans in the optical area recently.. And with the new high power blues everyone is getting, it won't be long before the diode burns the dust onto the optics and then the optics are ruined...

    Quote Originally Posted by norty303 View Post
    Question, did you leave it powered throughout? ?
    Absolutely not... Leaving the laser on throughout would contradict my risk assessment... Any time that machine is unattended, it is powered down, unplugged and the key is safely in my pocket... So it was only on during the show, probably a total of 16 hrs over the 4 nights...

    Quote Originally Posted by norty303 View Post
    I notice you use positive pressure fans with the open exhaust on top (and perhaps elsewhere) but if you switch it off, that all goes out the window, right?
    I have 4 fans on the front and 4 on the back pulling air in, with 2 on the side pushing air out and of course the huge vent on top to get the rest of the heat out... That vent was not by best design feature, should have put it underneath... All it takes is one drop of rain, and boom... Oh well, everyone makes mistakes, as the Dalek said, climbing off a dustbin

    Mark

  6. #6
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    Absolutely not... Leaving the laser on throughout would contradict my risk assessment... Any time that machine is unattended, it is powered down, unplugged and the key is safely in my pocket... So it was only on during the show, probably a total of 16 hrs over the 4 nights...
    Might want to revise your power scheme if you do a lot of events like that.
    My projectors are set up so that even with lasers defeated, the fans (and scanners) continue to run. This means it can be powered but safe overnight thereby reducing the risk of dust ingress and condensation forming. It's the same reason why most sound and light co's will run amps and moving heads overnight.

  7. #7
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    Hey Mark,
    I remember seeing that beast at one of the UKLEM's . Any chance you and it will be making it to the next one

    Adrian

  8. #8
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    Quote Originally Posted by norty303 View Post
    Might want to revise your power scheme if you do a lot of events like that.
    My projectors are set up so that even with lasers defeated, the fans (and scanners) continue to run. This means it can be powered but safe overnight thereby reducing the risk of dust ingress and condensation forming. It's the same reason why most sound and light co's will run amps and moving heads overnight.
    Most of the HSE I deal with insist that the laser is powered down and key fully removed at most events I do... Plus I never like leaving things running when I'm not there... Just in case

    Quote Originally Posted by RGbee View Post
    Hey Mark,
    I remember seeing that beast at one of the UKLEM's . Any chance you and it will be making it to the next one

    Adrian
    Hey Adrian, sadly it's looking unlikely as I have an all night show to do on 2nd Oct... But one way or another, I'll do my best... Either Friday for a day If I can get time off work or I might drag myself up there Sunday if I can survive with no sleep...

    Mark

  9. #9
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    Most of the HSE I deal with insist that the key fully removed at most events I do
    Yep, me too, that doesn't stop the fans running though

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