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Thread: Why my dot can turn orange but no other color...

  1. #1

    Default Why my dot can turn orange but no other color...

    Can someone explain this to me...yesterday I was shining my greenie around and noticed when I hit a certain area on a poster which is like a flourescent orange and pink, the dot turned a bright orange. What allows this to happen while the green stays green on every other color? By the way, I took a picture, and in the picture the dot was green while my eyes saw bright orange. I'll post it later tonight as I'm at work right now.

  2. #2
    *Retired* The_LED_Museum's Avatar
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    Default Re: Why my dot can turn orange but no other color...

    The orange/pink areas on that poster are fluorescent - that is, they absorb the shorter wavelength green light from your laser and re-radiate it in longer (redder) wavelengths as an orange color.
    The other colored inks or paints on that poster are not fluorescent, so they do not absorb the green radiation and re-radiate it in a longer (redder) wavelength.

    Orange and pink mail and UPS labels are fluorescent in the same manner. Shine a green laser on them and you'll see an orange reflection.

  3. #3

    Default Re: Why my dot can turn orange but no other color...

    red + green = orange [img]/ubbthreads/images/graemlins/smile.gif[/img]

    just so simple...
    when i light at anything red the dot is orange [img]/ubbthreads/images/graemlins/smile.gif[/img]

  4. #4

    Default Re: Why my dot can turn orange but no other color...

    You can produce other colors but you need to use shorter wavelength light. Below you'll read why green light works and the difference between Anti-stokes and fluorescence.

    Anti-Stokes Emission Always Outputs More Energy than the Operator Inputs
    Anti-Stokes emission, e.g., has been verified overunity (the medium outputs more energy than the operator inputs) for more than 50 years. In most (but not all) cases, at the time a photon is absorbed by a molecule in this effect, a collision with one or more other molecules adds extra energy to the absorbing molecule. Consequently the absorbing molecule receives excess energy over and above what it received from absorbing the photon, and enters a higher excited state than it would have entered from the absorption alone. That means that the molecule has collected additional excess energy in its "superexcited" state. The molecule is then free to decay from this superexcited state and emit a more energetic photon than it originally absorbed.
    This does indeed happen and is quite rigorously proven.
    However, usually in such a medium there are other Stokes emission processes ongoing, where a molecule absorbing a photon from its environment or input, simultaneously has its own kinetic energy reduced by collisions, and so it gives up energy as it absorbs energy. Hence it may enter an excited state less than it would have entered from absorbing the photon alone. Therefore this "subexcited" energy state [Fluorescence] can subsequently decay to emit a photon less energetic than the one it absorbed.

    Further info can be found here: http://www.cheniere.org/misc/antistokes.htm

    Question - What is flourescence? How does it work? ----------------- Fluorescence is when a molecule absorbs light of one energy and later emits light of a lower energy. Briefly, what happens is that upon absorption of the first photon, an electron is promoted to a higher-energy orbital. This raises the energy of the molecule by an amount equal to the energy of the photon absorbed. Electrons move very fast, as they are much lighter (factors over 1000) than atomic nuclei. When the electron is in its new higher-energy state, the most favorable arrangement of the nuclei changes a little. Because the nuclei are so heavy, they will (comparatively) slowly reorganize to their most favorable arrangement. This lowers the total energy of the molecule. It is still higher than in the ground state, but not as much higher as the energy of the absorbed photon.

    Further info can be found here: http://www.newton.dep.anl.gov/askasc...9/phy99540.htm

  5. #5

    Default Re: Why my dot can turn orange but no other color...

    Thanks a lot for that info, it really explains it.

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