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Plastic or glass that can block one colour/ wavelength?

  1. Dec 17, 2014 #1
    Hi, new member here, I know very little about physics so have no idea if this is a very basic question or not, but I was wondering if anyone knows the answer to the following:

    Does there exist a type of plastic or glass that (whilst remaining completely see through) can allow the user to see every colour through it except for one?

    Thanks.
     
  2. jcsd
  3. Dec 17, 2014 #2

    DrClaude

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    Staff: Mentor

  4. Dec 17, 2014 #3
    Look up notch filters. They are used, for example, in Raman spectroscopy.
     
  5. Dec 17, 2014 #4

    davenn

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    yes but doesn't quite fill the OP's comment ... definitely not optically transparent at other wavelengths



    http://www.semrock.com/filter-types-for-raman-spectroscopy-applications.aspx

    Maybe the same problem sure ? .... only looked at a couple of sites

    I wonder if visually looking through it if it appears transparent to everything ( like a sheet of clear glass) other than the notch wavelength ?
    that is what the OP is asking :)

    Dave
     
  6. Dec 17, 2014 #5

    cjl

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    The line filters from that site appear to be exactly what the OP is looking for...
     
  7. Dec 17, 2014 #6

    Drakkith

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    Pretty much any optical filter that blocks only a small range of wavelengths will do. The notch filter from the link above works perfectly. It blocks practically all of the light within the notch's wavelength range (stopband) and allows almost all of the light outside of this range to pass through. The line filter does the opposite. It blocks everything except a small range of wavelengths from passing. I have a filter in my astrophotography camera's filter wheel that works identically to the line filter. It only allows light around 656 nm to pass through. I believe the passband is about 10 nm.

    Wavelength is a better term to use here than "color" because color is both subjective and lacks an accurate way of measuring it. The color "red" exists over a wide range of wavelengths, and many people would disagree about where the color red begins and ends. There is no confusion if you use "wavelength" instead.
     
  8. Dec 17, 2014 #7

    davenn

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    Exactly :) which is why I did

    ( http://www.semrock.com/filter-types-for-raman-spectroscopy-applications.aspx )

    the notch filter, at least going by the graph ( lower right) would be OK. I was initially put off by the colouring of the filters used in their drawing but that was for the edge filters

    the line filter ( as in the lower left graph) appears to be a narrow band pass which wouldn't be any good as it would have the opposite effect to what the OP wants

    Dave
     
  9. Dec 18, 2014 #8

    cjl

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    Oh - you're correct. I was reading the graphs backwards.
     
  10. Dec 18, 2014 #9

    sophiecentaur

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    It's worth while pointing out that filters as precise as the ones in that link are seldom achieved with pigments or dyes. They will be Interference Filters, made with several layers of transparent materials, each of around a quarter the wavelength of the light, The multiple reflections between the layers ( at each interface) will cause constructive and destructive interference of different wavelengths. Interference filters are used to stop reflections on the surfaces of lenses (blooming of camera and binocular lenses) and to produce the stunning colours that you can get on thin oil films on water or in butterfly wings and bird feathers. Trying to do the same thing with pigments is hopeless because the way light interacts with the molecules in dyes is much less well defined.
    See 'Dichroic Filters' in this link.
     
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