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Are phosphor sheets used in CRTs transparent?

  1. Sep 12, 2013 #1
    and if they are, to what extent?
     
  2. jcsd
  3. Sep 12, 2013 #2

    berkeman

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    I don't think they are, but it would take some digging to figure this out. What is the context of the question?
     
  4. Sep 12, 2013 #3
    well, if you look at a CRT TV turned off, you just see blackness (and a bit of reflection of the screen), not tiny red green blue dots, so i think, maybe they are transparent.
     
  5. Sep 12, 2013 #4

    berkeman

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    Look closer with a magifying glass...
     
  6. Sep 12, 2013 #5

    berkeman

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    And use a flashlight. You should be able to see the phosphur surface, not the inside of the CRT. :smile:
     
  7. Sep 13, 2013 #6
    how very stupid of me. another thing, can you tell me if the indivudual particles of phosphor are at micro or nano scale? if they they are nano sized and embedded (closely packed) in a plastic sheet, would it be transparent.
     
  8. Sep 13, 2013 #7

    berkeman

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    It sounds like you would like to have a way to have a transparent coating that has the properties of phosphor? Are you going to use an electron beam to excite the phosphor? Are you aware of the X-ray generation issues with using an electron beam to excite phosphor?
     
  9. Sep 13, 2013 #8

    Baluncore

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    The CRT EHT voltage was used to accelerate an electron beam that could then be focussed and deflected to raster scan the phosphor screen. There is no need for EHT to cause a phosphor to emit visible light. The generation of X-rays of 10 to 30keV is best avoided.

    Visible light has an Energy = Plank's constant x Frequency. Three volts is sufficient as is demonstrated by the forward voltage of light emitting diodes.

    Maybe consider electroluminescent display technology where a phosphor is placed between the plates of a capacitor. http://en.wikipedia.org/wiki/Electroluminescence
     
  10. Oct 11, 2013 #9
    These phosphors can not be transparent even if embedded in a plastic film due to the difference between the refractive indexes of the polymer and the inorganic phosphor particles. However, if you need a transparent luminescent material there are glasses and single crystals for this purpose.
     
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