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Thread: "Safe" green laser pointer?

  1. #21
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    Quote Originally Posted by buffo View Post
    I thought your fog screen was designed to sit on the ground and the fog flowed upward? Are you saying that you can invert it and have a "falling" fog screen too? If so, I must have missed that part of the original thread!
    Actually, my old Fogscreen was designed to be in any orientation as the fog was piped into the fogscreen. My new fogscreen has an internal tank so it can only blow fog downward. That is how I have kids walk through it on Halloween.

    If you used straws for both the mist channel and the surrounding "curtain" air, would there be any difference vs the honeycomb material? I'm wondering what the specific advantage the honeycomb shape has with regard to maintaining the smooth laminar flow.?.
    To be honest, I think the round shape of the straws actually provide a better laminar flow. The Honeycomb material I am using is more uniform though. My first fogscreen was made out of drinking straws and I noticed that from one straw to another, the "roundness" varied quite a bit. How much any of this affects air, I don't know. I just know that both work.

    It's hard to make a comparison though because the honeycomb cells are 3/8" and the straws were 1/4". The straws were longer too so, all of these variations make it hard for an honest and fair comparison.

  2. #22
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    Up to down makes the most sense if you are going for a screen, gravity working for you. Maybe you could run a flow sim before you go ahead and build your next one.
    I think SimScale could do it and it should be free. You could try different configurations testing different shapes before committing time and material.

  3. #23
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    I finally got around to shooting some video...

    This is a demonstration showing what it would look like just running the fog through a row of straws without a laminar curtain and then with the laminar curtain. This goes back to what I was saying earlier... a fog wall with just straws will work but it is WAY better with a full laminar air curtain.


  4. #24
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    Holy crap! It's amazing the difference that the laminar flow air curtain makes!

    OK, so if I'm ever going to build one of these, it *must* include the outer air curtains to sandwich the fog in-between.

    Wondering what it would look like with a standard haze machine supplying the fog instead of the ultrasonic humidifiers? I mean, obviously the fog wouldn't dissipate much, but I'm thinking that if you used a fog chiller to cool the haze before you sent it through the laminar flow head it might spread out once it hit the floor and then stay on the ground... That could be a neat effect for halloween!

    Brian, I know you've posted it before, but please refresh my memory... What's an approximate cost to build one of these?

    Adam

  5. #25
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    You could in theory watch a flick on there lol. And I guess a haze is a no no, because some clients do not want haze in their event, so a water mist is more suitable. Ever tried laser projections on it? Skrim screen (albeit not that light and possibly deadly)

  6. #26
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    Quote Originally Posted by Ableton69 View Post

    Ever tried laser projections on it? Skrim screen (albeit not that light and possibly deadly)
    I have. It looks pretty cool. One of the best things is that you can turn the skrim on and off! So you are free to do graphics and beams and one will not interfere with the other like a physical skrim.

  7. #27
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    Quote Originally Posted by absolom7691 View Post
    I have. It looks pretty cool. One of the best things is that you can turn the skrim on and off! So you are free to do graphics and beams and one will not interfere with the other like a physical skrim.
    Oh no, you gave me an idea. And when I get idea, money goes down the drain

    The same system but pushing the mist up, how far do you think it can go before breaking up?

  8. #28
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    Quote Originally Posted by buffo View Post
    Holy crap! It's amazing the difference that the laminar flow air curtain makes!

    OK, so if I'm ever going to build one of these, it *must* include the outer air curtains to sandwich the fog in-between.
    For superior image quality, absolutely!

    Wondering what it would look like with a standard haze machine supplying the fog instead of the ultrasonic humidifiers? I mean, obviously the fog wouldn't dissipate much, but I'm thinking that if you used a fog chiller to cool the haze before you sent it through the laminar flow head it might spread out once it hit the floor and then stay on the ground... That could be a neat effect for halloween!
    When this project was still on paper, I thought about the different methods to generate fog. I settled on the misters because it was nothing but clean water vapor and they are one of the most inexpensive components when considering all of the other parts needed. A hazer would work but I the hang time would probably be a killer. I also don't know about any build up inside the fogscreen. That's why I never used a glycol fogger. I thought the build would be a bitch to clean.

    Brian, I know you've posted it before, but please refresh my memory... What's an approximate cost to build one of these?
    The honeycomb was the most expensive component of this screen. All in all, I would say this was right around $1800~$2000.

  9. #29
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    Quote Originally Posted by Ableton69 View Post
    Oh no, you gave me an idea. And when I get idea, money goes down the drain

    The same system but pushing the mist up, how far do you think it can go before breaking up?
    Isn't that how all ideas go???? lol

    Well, with lasers, it's a lot more forgiving than a video projection. Vector vs "raster". Even as the fog starts to break down, it would still look okay. But it's hard to say about breakdown. There are a ton a variables. The other thing to keep in mind, laminar airflow works when the environment is fairly calm. Outdoors, you would need almost perfectly still air. It's one of the reasons why I build a tunnel for halloween. Partly for the spook-factor but mainly to keep the wind from destroying the effect. That being said, in a room with "unlimited" height, and with my fogscreen, I would say entropy would set in around 12 feet. I have never tried though so, that is complete speculation.

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