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# Are there Phosphors that react only to specific frequencies of light? Answered

Are there phosphors that only produce a color of visible light when struck by a specific frequency?

If so, what would happen if this phosphor was struck be two beams of light at right angles, with each beam at half the "trigger" frequency?  If this would not result in an effective "trigger" frequency at that point, is there another method of achieving that effective frequency at a point, with two beams crossing at a single point, where the phosphor lies?

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## 6 Replies

hoonflap (author)2014-10-09

I know that this thread is a bit old, but I found it while looking for something else and have some info that may help. If you haven't found a satisfactory answer thus far, I believe two-photon excitation is what you're describing.

http://en.wikipedia.org/wiki/Two-photon_excitation_microscopy

gschoppe (author)2011-05-23

well, the overall concept that came into my head was finding a way to address a pixel in three dimensions, using a similar method to how those suspended laser etchings are made.

The thought that came into my head was initially to use two low intensity lasers, focused on a block of clear acrylic with phosphors embedded throughout... however, by the result would likely be too muddled to discern, if each beam excites all the phosphors in its path, to some extent.

Goodhart (author)2011-05-22

If so, what would happen if this phosphor was struck be two beams of light at right angles, with each beam at half the "trigger" frequency?

As I understand it, nothing.  Think of it this way; you spray water at a source and then spray some from a "different" angle...will the force increase? Or will one "scatter and interfere" with the other?   The latter is most likely to happen.

gmoon (author)2011-05-22

That might be possible...although not by mixing two sources of the same wavelength.

In the additive color model, mixing red and green produces yellow. And red and blue create magenta. But magenta is non-spectral. It's more of a mixture of two colors than a discrete wavelength.

So some of the magic of additive color is perceptual. Just like like florescent bulbs aren't full spectrum--they are a mix of narrow bands that fool the eye into perceiving white light.

Two light sources wouldn't mix at a point. They would mix proportionally to their distance. If they were carefully focused and directed to a point, there wouldn't be an advantage to use two separate sources... :-)

lemonie (author)2011-05-22

What exactly do you want to do?

L

PointyOintment (author)2011-05-21

I don't have a great understanding of this, but in my physics class I learned that the incoming photons must each have sufficient energy to raise the electrons up to the next energy level. Therefore, any light above a certain frequency (which is specific to each phosphor) will make it glow. But the main problem with your idea is that frequencies do not add together. If you combine two beams of light of the same frequency and the same intensity, you get a beam of light with the same frequency and twice the intensity.