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Thread: minimum mW for visible beams

  1. #1
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    Default minimum mW for visible beams

    I am working on a project for our local science meusem for a kiosk about light and need to know the minimum power for each red (635 & 650) green (532) and blue (473) (in regular indoor lighting/no smoke) to have a static visible beam

    thanks

  2. #2
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    Cool

    Normal indoor lighting? As in, the sort of lighting you'd have in an office environment? And no fog? You're talking about a lot of power then!

    If you want to just barely be able to see the beam, I'd guess somewhere north of a full watt of red, and at least a watt of blue. Just 500-750 mw of green will probably be enough though. This will look rather pathetic, but you should be able to see the beams.

    If you want a beam that really stands out - one that is clearly visible like beams normally are in a dark room with fog in the air - then you're looking at 5 to 6 watts of red, 3 to 4 watts of blue, and around 2 watts green. Minimum.

    Why the "no fog" restriction?

    Adam

  3. #3
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    Default

    Quote Originally Posted by buffo View Post
    Normal indoor lighting? As in, the sort of lighting you'd have in an office environment? And no fog? You're talking about a lot of power then!

    If you want to just barely be able to see the beam, I'd guess somewhere north of a full watt of red, and at least a watt of blue. Just 500-750 mw of green will probably be enough though. This will look rather pathetic, but you should be able to see the beams.

    If you want a beam that really stands out - one that is clearly visible like beams normally are in a dark room with fog in the air - then you're looking at 5 to 6 watts of red, 3 to 4 watts of blue, and around 2 watts green. Minimum.

    Why the "no fog" restriction?

    Adam

    im not sure how i ended up with two threads but anyhow

    the idea is a demo of using light for communications, so the idea was to modulate a laser with audio... have two kiosks with handsets, each kiosk has a laser aimed back at the other for a full-duplex audio link...

    its a science meuseum so its not as bright as say, an office building, but its not dark either... no fog becuase its just not practical

  4. #4
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    Default

    Sorry to say but you need to have 500mw(532nm)X400mw(473nm)X1000mw(635nm) for a good show with smoke and light effects so no smoke and some light.... you need multiply it by 2.

    So.

    1W green or 800mw Blue or 2W red. Thats reality. No "my 100mw works great" doesn't work here...

    As far as I understood only one beam is needed so my config will work. If you plaining to scan Buffo's power solution is needed.
    Last edited by Dr Laser; 04-08-2008 at 21:51. Reason: Thanx mliptack
    I hired an Italian guy to do my wires. Now they look like spaghetti!

  5. #5
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    Quote Originally Posted by Dr Laser View Post
    Sorry to say but you need to have 500nm(532nm)X400nm(473nm)X1000nm(635nm)
    He means "mw" instead of "nm" for the notation outside the parenthesis.

    I would still say that is a bit underrated... my 532nm that is performing around 1watt is visible with the lights on, but it is in no way spectacular. Also if you are not facing the output of the beam it is much less visible.

    I am not sure what the type of communication demo you are doing but I've always wanted to try to do the old window reflection "bounce" pickup. Of course for legal purposes only... just to see how effective it is.

    -Max

  6. #6
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    Have you considered doing something to make just part of the beam, or maybe a spot visible? I'm not sure how this would affect a communication link, but it would probably be doable for less $$ than getting a powerful enough laser to have a visible beam in normal office lighting. (but hey, it zaps bugs at the same time!)

    idea #1) for a spot, I'm thinking of something like a piece of glass or other transmissive material that would show the spot but let enough of the beam through so communications would still work. Maybe make one side use red, other side use blue, and see two spots.

    idea #2) for a beam, what about a translucent cube, or maybe a box, filled with something making the beam visible. This may make communication poor though.

    idea #3) how about hollow translucent box, hooked to a button activated fogger/hazer but enclosed so the fog does not get into the general room. If it could be made to work, people could chat through it, then someone hits the button, box fills with fog, and "ooh" pretty beams are visible (but chat may fail till the fog clears).

    Just some random ideas

  7. #7
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    Default

    How about one of those little ultrasonic humidifier blocks in a sealed lexan case. You could put a tiny amount of bleach in the water to keep things from growing and do a basically closed system.

    Chad


    When the going gets weird, the weird turn pro.


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