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changing laser color

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yesterday i was messing around with my green laser and some lens from an old Polaroid and i noticed something weird. when i put the laser up to a small blue lens it slightly changed the tone of the laser. you could barely tell but it had a bluer color to it. is it possible to drastically change the color of your laser like from red to orange or from green to bluish green using colored lens or glass?
 

Amnizu

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No, because the wavelength of light emitted will be the same on either side of the glass, 532nm. It's not like white light, which you can split into many different colours because white light is made up of the entire rainbow.
 
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yea, isn't that how they make a green laser in the first place? IR put through a crystal of some sort which does something to the frequency? like double or half it?
 

Switch

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bobobob121 said:
yea, isn't that how they make a green laser in the first place? IR put through a crystal of some sort which does something to the frequency? like double or half it?
Yea but it's not putting your laser through colored glass.It's a little more complex process.You pump energy into the crystal and get it to emit it's own coherent radiation, I think.The green photons are newly produced ones, not the same ones generated by the diode but with the wavelength changed. :-/( I think, could be wrong though)
Eighter way, laserwayne, what you said is not possible.What you saw was probably a trick of your own eyes.
 

Scriabin

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The reason of seeing strange colors by shinig a green laser on certain surfaces, is because of fuorescence. For example, if you shine a fluorescent dye(ex. a marker) it absorb green light and emits other light of other color. But the light emitted isn't laser light, only incoherent light.
The green lasers work with non-linear crystal KTP: when IR photons hit the crystal some of the light passes through, but some of the photons are caught by molecular lattice of the KTP, and can escape only when they are increased at enough energy(532 nm light is more energetic than 1064).
 

Ace82

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Scriabin said:
The reason of seeing strange colors by shinig a green laser on certain surfaces, is because of fuorescence. For example, if you shine a fluorescent dye(ex. a marker) it absorb green light and emits other light of other color. But the light emitted isn't laser light, only incoherent light.
The green lasers work with non-linear crystal KTP: when IR photons hit the crystal some of the light passes through, but some of the photons are caught by molecular lattice of the KTP, and can escape only when they are increased at enough energy(532 nm light is more energetic than 1064).
This guy knows what he's talking about. incoherent light is perceived from your eyes as a reaction of coherent light reflecting off of another surface, right? So although the laser appears to be “orangish”, the coherent light will never change it's wavelength.
 

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Ace82

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As you can see from my picture, the green laser light is reflecting off of the highlighter. As far as your lens changing the "shade" of your green laser, it was most likely incoherent light.
 

Scriabin

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Ace82 said:
[quote author=Scriabin link=1206475622/0#5 date=1206553334]The reason of seeing strange colors by shinig a green laser on certain surfaces, is because of fuorescence. For example, if you shine a fluorescent dye(ex. a marker) it absorb green light and emits other light of other color. But the light emitted isn't laser light, only incoherent light.
The green lasers work with non-linear crystal KTP: when IR photons hit the crystal some of the light passes through, but some of the photons are caught by molecular lattice of the KTP, and can escape only when they are increased at enough energy(532 nm light is more energetic than 1064).
This guy knows what he's talking about.  incoherent light is perceived from your eyes as a reaction of coherent light reflecting off of another surface, right?  So although the laser appears to be “orangish”, the coherent light will never change it's wavelength.[/quote]

Yes you right ;), maybe I'll say obvious thing, but the original laser light remain always the same...the spot that you see on the marker, is a result from the initial 532nm and the emission spectra of the dye used in the marker, (sometimes rhodamine 6G for orange,sodium fluoresceine for yellow, coumarine for blue). Moreover, only if a light is monochromatic is impossible to change the color,because only a wavelenght is present.
For example, a kripton laser can emits white laser light: it is coherent but can be filtered to pass the desidered colors. On the opposite, a simple LED emits not-coherent light, but it is monochromatic and can't be changed in color.
 

Cyparagon

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Switch said:
Yea but it's not putting your laser through colored glass.It's a little more complex process.You pump energy into the crystal and get it to emit it's own coherent radiation, I think.The green photons are newly produced ones, not the same ones generated by the diode but with the wavelength changed.
The 1064nm wavelength is new energy, but the KTP just doubles the frequency of this energy - so you're half right.
 

RA_pierce

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I don't think a 532nm laser can cause florescence with a bluish color. The light from florescence is always of a longer wavelength than the light that causes it. For example, green light on an orange hilighter fluoresces orange. A red laser on a orange hilighter does not fluoresce. Violet light can get a green hilighter to fluoresce green, but a green or red laser can't. The bluish color you saw was probably just an illusion. Depending on the surface my laser's dot is on or the contrast of the walls/ objects in the area, the beam can appear more yellowish or bluish. For example, light grey may appear white against a black background but when against true white, it would appear darker.
 

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Cyparagon said:
The 1064nm wavelength is new energy, but the KTP just doubles the frequency of this energy - so you're half right.
Always wanted to know that. ;)
For example, light grey may appear white against a black background but when against true white, it would appear darker.
There you go
 

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nikokapo said:
this has become one of the most informative thread.

i just learned so much :O  :eek:
Have you looked at the same color illusion thingy? I find that amazing.I have to stare and concentrate at the A and B tiles for a few seconds to be able to tell that they're the same.
 

Scriabin

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Yes, in general the wavelenght of fluorescence is longer than the pumping light. This is because when a photon hits an electron, this jumps to an upper energy level; than this electron, once in this upper state, loses small part of its energy because this is an unstable condition(by termal dispersion, trasferring energy to other atoms) and when comes back to the initial ground state, releases all the energy absorbed first minus the energy lost previously when it was at upper state. Since high energy means lower wavelenght, it is not possible in normal condition to obtain a fluorescence of lower wavelenght.
 




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