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Fibre optics for use in lighting?

  1. Apr 15, 2014 #1
    Is it possible to send enough light down a fibre optic cable to produce say 1000 Lumens? How would I go about calculating this?

    My thoughts here are using fibre optic cables to transfer light from the rooftops of buildings to the rooms inside. Is it possible? I know fibre optics are used to transfer power in MRI machines.
     
  2. jcsd
  3. Apr 15, 2014 #2

    Drakkith

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    I would think so, as long as you can get 1,000 lumens into the fiber optic cable to begin with. The problem you'll run into is that without some sort of small, bright light source, like the LED's and lasers they typically use, the amount of light you can pump into them is extremely limited thanks to the very small aperture of the opening. You'd need to focus the light from a much larger area down and get it into the cable. (Without burning up the cable)
     
  4. Apr 15, 2014 #3

    wukunlin

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    A couple of years ago in our labs we had a PhD working on using a lossy fibre to wrap around electric fences so they light up at night to prevent our dairy farmers from zapping themselves. They were able to illuminate over a hundred metres of electric fence so I think you can easily transfer that much energy through your fibre.
     
  5. Apr 15, 2014 #4

    davenn

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    ummm ... and how did the electric fence produce the continuous light source along its length that was injected into the fibre to light it up ?
    The only time I have seen electric fences produce light was from small sparks where it was shorting out to ground

    the light source for the fibre must have been back at the start of the fibre, a LED or globe shining into the end of it
    ya don't need a PhD to work that out :wink:

    cheers
    Dave
     
  6. Apr 15, 2014 #5

    wukunlin

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    I never said the light source came from the fence?

    The student was probably working on a side project for a partner in the dairy industry. I don't know the details but you do need to find ways to produce fibres with consistent loss so you get a even glow along the fibre (and the fence) instead of just a small spot at the end.
     
  7. Apr 15, 2014 #6

    berkeman

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    Seems like the loss would need to be inverse exponential to give an even glow along the length of the fiber -- even harder...
     
  8. Apr 16, 2014 #7

    UltrafastPED

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    All you need are defects in the fiber surface, more or less evenly distributed ... then it leaks.

    When it gets too dim, you need to inject more light. But here they total distance wasn't too great, so probably most of the light was simply transmitted.

    I've bumped into an electric fence more than once ... but I did it in full daylight, so this would not have helped me!
     
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