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Why brown sunglasses filter blue light?

  1. Dec 28, 2015 #1
    Im selecting sunglasses for the holidays. How come brown sunglasses will filter blue light? How about green sunglasses? it's supposed to filter some blue light.. how much and why?
     
  2. jcsd
  3. Dec 28, 2015 #2
    From what I've seen from looking a few things up, it looks like that rose colored sunglasses also filter blue light. In addition, orange colored safety googles filter UV light. If you think of the electromagnetic spectrum, or even rainbows for that matter, this begins to make sense. Brown (just a darker shade of orange typically), orange, and red light all lie to one side of the spectrum, while blue and UV light are on the other side. And light is either reflected or absorbed when it hits a surface; what is reflected is not absorbed and vice versa. So, what happens with orange (or brown) or red colored things is that they reflect orange (or brown) or red and absorb blue and possibly (depending on the material) UV light. In the end, this results in you seeing the reflected light, and not seeing the absorbed light when you look at the object.

    I'm not sure about green, as it lies more in the middle of the spectrum so I hypothesize that it would filter less blue light than brown sunglasses.

    Also, if you're looking at polarizing lenses, that's a whole different concept.
     
  4. Dec 29, 2015 #3
    Yes. It's polarizing lenses. I initially got the brown.. the visual is clearer than average because it's supposedly filter all blue (removing all haze).. but I changed it to green because brown only good for older people. But it's same concept as what you described above. Is it not? I know polarizing lens block all horizontal light.. but this is separate from the colors and blue filtering?
     
  5. Dec 29, 2015 #4
    It's a similar effect but polarization doesn't necessarily depend on the color of the lens. For instance, here are some red lenses that are (advertised to be) polarized:
    https://www.amazon.com/Replacement-Polarized-Lenses-Oakley-Sunglasses/dp/B00MZL6ZAQ
     
  6. Dec 29, 2015 #5
    Also, more fundamentally, polarization deals with eliminating all but one plane of vibration for electromagnetic waves. Reflection and absorbing on the other hand are caused by atoms in the material absorbing the light then "spitting out" the excess energy.
     
  7. Dec 29, 2015 #6

    sophiecentaur

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    It's worth while pointing our that it's not so much an 'elimination' of all planes but one because that would end up with very little light getting through. When light passes through a polariser, the polariser selects just the component of the wave(s) in a particular plane. It actually lets through half of the energy of unpolarised light.
    Also, the filters in sunglasses are usually very broadband and let some proportion of all wavelengths through (except for joke glasses) or they would distort the colours too much for comfort. You'd normally describe the lens colour as a "tint".
    Aamof, I have been after a photographic filter which would have a sharp cut off near the blue end (rather than just a UV filter). Haze would be reduced and pictures taken in snow and mountains could be much improved but there would still be enough blue to give believable and natural looking colours. I have looked in catalogues but can't find what I'm looking for. Such a filter would look 'warm' but not too much, as there would be a reasonable amount of longer wavelength blues. Sorry - that's only a very minor hijack.
     
  8. Jan 4, 2016 #7
    I have personally tried the maui jim brown glasses (HCL bronze) versus grey and green in the optical store. There is just obviously greater contrast in the brown glass.

    Is it entirely due to our eyes unable to focus blue light because of our adaptable to the sky blue filter.. or what other causes why our eyes is not good with blue light. About the brown glasses.. could it have greater contrast because of the brown colors itself? What you think?

    See http://www.mauijim.com/en/shop/sunglasses/rimless/sandhill for the lens color scene comparison.
     
  9. Jan 6, 2016 #8
    Guys this is simple, a paper filter will filter every other light frequencies except the color we see (this is going to be controversial please do not talk about this sentence i can't express it any better) like blue filter filter light rays other than blue and white filter just lets all rays to pass through(again controversial alert) the brown the op talked about May have contain brown pigment which filter the color blue only(again...)
    Please correct me if any mistakes.
     
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