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Thread: Fluorescence/phosphors

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    Default Fluorescence/phosphors

    I am interested in building a phosphor-plate to beam some 445 on, as an effect. But where can one get the best material for such a task? Phosphor is a broad term, what to look for more exactly when wanting to maximize light output from 445nm laser input?

    Example:
    http://www.youtube.com/watch?v=h29SwJDXMBc

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    ..These guys are / offer the best product.. http://www.wildfirefx.com/products/p...minescent.aspx

    (imho..
    cheers..
    j
    ....and armed only with his trusty 21 Zorgawatt KTiOPO4...

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    Let me clarify, I did not mean luminescent - glow in the dark effect, but direct fluorescence effect - when lasers are beaming the phosphor the plate shine instantly.

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    And maybe someone else could clarify to me why why BMWs laser-headlights are said to be able to output so much more light or more effectively, than for example using white LED (blue diodes shining directly into an integrated phosphor layer)? Are the effects stated differently; 2w 445 laser diode gives 2w optical effect, 10W LED White diode draws 10W effect but have what optical effect? There must be a substantial effect loss when using phosphor plate of such large size and with lots of air between source and phosphor.

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    Lasers are specified for power out, LED's are specified by consumption, so you can't compare them directly. Also, lumens depend on eye sensitivity for wavelength, and candelas depend on the stereo angle (related to divergence) of the emission. So comparing LED's and lasers isn't easy.

    A better way to look at it in this case is that assuming you catch all of the emission on the phosphors, and that the phosphors are efficient at converting its energy to light at wavelengths you need to see, it doesn't matter if there is air between source and target screen so long as it won't absorb the energy between them. That leaves the source efficiency. As LED's are maybe 30% efficient in high power diodes, (maybe more, I haven't been watching that detail for a few years), they beat LED's. For a long time I have forecast that laser diodes will be embedded in fluorescent capsules for domestic lighting, replacing LED lamps and making them look as inefficient as LED lamps make compact fluorescent look in comparison. Risks of danger from lasers and methods of safe encapsulation against easy tampering will be developed before they end up in shops, and diode prices would have to fall a lot, production scales would have to rise etc, but it will happen.

    Assuming you mean fluorescence and not phosphorescence, look for dayglo paint. You may get other colours with laser dye powders added to clear varnish. Probably not as cheap though. If you're aiming to mix to mix powders on one screen so one gets excited with one wavelength, while another is excited and glows at a different colour in same space when lit by a different source wavelength, then I'm not sure if it's practical, or even possible. It would look cool though, if it is.

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    Certain liquid laundry detergents are reactive to UV(ish) light ("blacklights" and 405nm lasers), but not sure how well it works with 445. It can come in handy when you want something to look "normal" when the lights are on.

    -Sal

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    Phosphors in the States and Europe are hard to get for two reasons, lack of demand and national security.

    Most fluorescent materials have a mix of phosphorescent and fluorescent properties. (ie.. storage and slow release, vs. instant conversion)
    The slow release materials all instantly convert as well, so if your not trying to modulate the light (ie video) you can use the phosphorescent materials, which you CAN get.

    You can get all the copper doped ZnS you want, which is the medium persistence yellow-green stuff you see in glow in the dark stars etc.
    You can get all the YAG based and Strontium Aluminate based long persistence material out of China (ie the Ebay glow stuff, led lighting blue to white converters)


    Anything else will have to be organic, ie the dye based and florescent paints.

    Otherwise the short persistence materials you want mostly come from one plant in the UK and a few plants in China and cost about 80$ a gram.

    Your only other chance is to find the Phosphor Cookbook section of the Phosphor Handbook (Yen and Weber) and synthesize what you want from scratch. This requires a oven that can reach 1100'C or higher, and usually a tank of carbon monoxide to run the reducing reaction in the oven. Most of the usual phosphors actually need the more expensive upper level lab ovens that get to 1500' C, for synthesis. Neither is easily accessible to a hobbyist (It helps to be a grad student)

    For reasons I can't get into in public,(Actually I can only guess why and was asked not to speculate in public) a certain agency sucks up all US made non lighting phosphor materials.

    Yes, I've had professional reasons to look into this, three times in the last three years. That's all I can say in a public forum. Considering whom I was working for in the past three years, if I cant get it, the odds of a hobbyist finding it are nil. I did end up with a few 10 gram bags of samples at 50-80$ per sample and one Ebay purchase. The Ebay vendor was closed down within a week. Those samples stayed at my employers when I left for a better job.

    If you cant get what you want from Wildfire, who do have some short persistence materials, oe Ebay, you'll have a tough time finding what you want. You may have to make it. This is one class of materials that you very much need to be a incorporated company to purchase.

    10 grams of heavy, often toxic, ceramic powder does not make much paint, in fact it would be wise to avoid using paint as a binder, there are other materials.

    Steve
    Last edited by mixedgas; 01-15-2014 at 05:35.
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    Thanks for very interesting information.

    So if I want an effect like the youtube video I posted, what type of material would be best, to maximize instant light output?
    BTW, what are the risks of overheating such material, can a 1x1cm piece take 8W 445nm laser?

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    can a 1x1cm piece take 8W 445nm laser ?
    Absolutely not!
    All inflammable materials will ignite in seconds at such intensities. (apart from indirect exposure risks)

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    what's the spot size on the phosphor color wheel from the casio projectors?

    Quote Originally Posted by -bart- View Post
    Absolutely not!
    All inflammable materials will ignite in seconds at such intensities. (apart from indirect exposure risks)
    suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.

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