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Thread: "Safe" green laser pointer?

  1. #31
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    Quote Originally Posted by buffo View Post
    *OUCH*!

    OK, I guess I'll hold off for now...
    Keep in mind, that was for my current fogscreen. My first incarnation (https://www.photonlexicon.com/forums...screen-Project) was only about $800. That used almost 9000 drinking straws and a shit-load of patience to construct. I also got a killer deal on the fans. It was cheaper and worked fairly well.

  2. #32
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    Wonderful to see! I'd love to see the effect of your screen live.

  3. #33
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    Quote Originally Posted by Eidetic View Post
    Wonderful to see! I'd love to see the effect of your screen live.

    Thank you! If you and Chris ever get a South-Western LEM going, I would be game to show it off. I'm sure Chris's abstracts would look great on it! SELEM is just too far for me to transport this thing practically so it really hasn't been in the cards. Maybe one day...

    @Adam, here is a video I put together (finally) showing how I set this up so you can see what is involved:


  4. #34
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    Me and my ideas

    For now nope lol, I have so many things on my plate, I better finish something before starting another. But thanks for the info, in the future I may look into it.

    The cost is not that much when you think about it, I am sure an event agency would hire it (tech firms especially), and pay well too. 5-6 gigs and you are payed off. If you are not already doing it, you should seriously consider it.
    The unit looks VERY clean and professional. Way I picture it, floor mounted on a speech event or something and bam!, blackout, it activates and a laser projects a logo on it. 1200$ pls, ty, bb. And how much exactly to charge, that depends where who and how long.

    An event manager I sometimes work with got a gig from the city hall for a stage or a truss for 3 days(I dont remember exactly) and they gave him a budget of around 2000 euros. He went out and bought the whole thing for 2800 and now he rents that out too.
    Clients are in most cases oblivious, and have in mind that there are 2-3 agencies before you too, so the higher up the food chain, the juicier the pie.
    But, higher up the food chain, the more oblivious too, so prepare yourself for a lot of... lets say, uninformed questions

  5. #35
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    I was not aware of the fact that the fog is confined to a single row of nozzles in the laminar flow portion. I assumed that there would be at least an inch or two of fog, with a couple inches of "air curtain" on either side to contain it.

    Interesting... I'm surprised that it's as visible as it is given how thin the fog field is. (This also explains why you can see the individual "nozzles" of fog near the outlet.) Is there a specific benefit to having the fog layer that thin?

    How are you adjusting the "density" of the fog? Are the ultrasonic humidifiers adjustable themselves, or do you simply vary the speed of the fans pushing the fog into the laminar flow section?

    Adam

  6. #36
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    Quote Originally Posted by buffo View Post
    Interesting... I'm surprised that it's as visible as it is given how thin the fog field is.
    There is a little trickery in physics at work here. I'm projecting the images "through" the fog so, due to the MIE coefficient of the tiny water particles, the image is very bright and clear when viewing head-on, even with the lights on. As you move away from the center, the light scattered becomes less and the image becomes less visible. In fact, if you were on the side of the fogscreen with the projector, so little of the light is reflected back that you can really only see the image in the dark and even then, it's very dim.

    Is there a specific benefit to having the fog layer that thin?
    The thinner the better. The clarity of the image is dependent upon the termination point (the screen). Since the divergence of the projector is huge, if the termination point were thicker, you would see an extruded image. Think of it this way, each droplet of water as a termination point, like a skrim. Imagine how a laser would look if you had 50 or 100 layers of skrim material instead of just one. You would have 50 or 100 images, all a different size since each subsequent layer is further from projector. With laser vector art, it isn't as bad but with a static "raster" image, it become unrecognizable beyond a certain point and that point is reached very quickly. This is demonstrated in the video I posted with the air curtain off and then on. The primary change in that video is the thickness of the screen.

    My fogscreen's fog layer is only .375" thick at the output. I would love for it to be thinner but the water condensation would be too bad in the honeycomb if I went thinner and there would just not be enough fog to make 3000 lumens workable, I'd have to go brighter. So, .375" seems to be a happy medium between image clarity and image quality/brightness.

    How are you adjusting the "density" of the fog? Are the ultrasonic humidifiers adjustable themselves, or do you simply vary the speed of the fans pushing the fog into the laminar flow section?
    You nailed it. All I am doing is adjusting the speed of the fog fans. The speed of the exiting fog/air has very little effect on the air curtain as a whole. The speed of the fog fans really only governs how much fog is pushed through. The air curtain ultimately determines the speed of the fog. For density, the air curtain speed matters too, to a degree. The faster the air curtain moves, the thinner, faster, and sometimes messier the fog layer gets. Because of this, it's the reason why I made everything on this fogscreen variable, hence the DMX interface. Outdoors, I run the air curtain fans a little faster to help against the constantly changing air. For indoor use, I run the air curtain a little slower since it looks better.

    The foggers are just on or off so, there is no adjustability there.
    Last edited by absolom7691; 05-28-2019 at 07:59.

  7. #37
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    Thanks for indulging my curiosity! Your explanation re: the thinness of the fog being compared to a scrim makes perfect sense. Makes me want to see this in person all the more!

    Is there a specific reason you went with so many individual PC cooling fans vs something larger? I'm thinking that a couple patriot fans running on AC via a speed controller would be cheaper and maybe quieter too... Or was it just a matter of using what you had on hand?

    Something else you said in the video kinda confuses me... You pointed out a drain tube that collects condensation from the laminar flow section and sends it back to the water tank. But the fog portion of the laminar flow section is just one row thick, and the bottom of those rows have fog coming out, so how are you collecting any drips without interrupting the fog flow? Or are you actually collecting the condensation from the chamber above the laminar flow portion so the water doesn't get into the center flow passages for the fog? And if so, do you still get drips from those passages? (I would think you would...)

    I have to say, I'm still intrigued by the concept. I'm just suffering from sticker shock! And yeah, I guess if I were to use a standard fog or haze machine instead of the ultrasonic humidifiers I would soon overwhelm everything with an ever-increasing layer of haze. It's just that dealing with water (and all the drips/condensation issues) in close proximity to the electronics for the fans seems like a bad idea.

    Adam

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