changing laser color

[Ace82]

Wow. Just a little over my head. I am more of a visual learner. Scriabin, I feel honored reading your input. It's funny how there is a logical explanation for most things...

And Switch, that color illusion is really a trip! This is a good example of why you can’t always believe (and especially solely) what your eyes see! That’s why I try to always keep an open mind.

 

[Tallaxo]

Red lasers will actually flouresce too. However they do so at a longer wavelength into the infra red , so you can never actually see it with the human eye.

Jase

 

[Gibs]

Hi everyone , I am new to this forum and this is my first posting. Sorry if my english is not perfect, but I am from Quebec, Canada and I usually speak french, so I will try to do my best to be well understood. So feel free to correct me if I'm wrong. Thanks.

I've found this topic interesting and I have a theory on this one that may sound like a question. What if the blue coating lens that Laserwayne uses as blocked most part of the IR, would it change the final result ?

I understand that IR is not visible to the human eye, but what if, by mixing it with other "colours" makes it kind of "visible" by resonnance... After all, wavelengths contained in laser's component are harmonics.

 

[Switch]

I doubt mixing IR with green would have any effect on how we see the green.I mean, green+invisible=green.If that was true , you would be able to see IR with the bare eye by shinig green light on it, thing which I don't think I've ever heard of. :-/

 

[likewhat]

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).

I dont like this description very much.

The KTP crystal is transparent to light, you can see right through them. low intensity IR light will shine right through a crystal with 100 percent transmission assuming no reflections or impurities. In fact the index of refraction at both the input and doubled frequencies has to be the same for frequency doubling to work properly.

When you shine light on to one of these crystals a polarization occurs in the crystal that follows the electric field (consider electrons in atoms following the electric field). At high intensity there is a polarization that occurs that is 2 times the input frequency due to a Chi^2 nonlinearity, the electric field driving this polarization is E^2, the input electric field squared. From simple math you know that exp(iwt)*exp(iwt) = exp(i2wt). So, now you have a polarization that is at a frequency of twice the input frequency. This polarization oscillating at 2w can then transfer energy into an electromagnetic wave (this comes from maxwells equations which you can look up if you are interested). So the output of the crystal (assuming it is lined up such that this process can occur) will be the input 1064nm light as well as 532 nm light that was created when the polarization oscillating at 2w transfered energy from the 1064nm input to electromagnetic radiation at its frequency. Now to get your green beam alone you just need a mirror that only passes the green light and dumps the IR light.

I know that description was a little more complicated, but nonlinear optics is not easy to understand without an advanced math background.

 

[MarioMaster]

I doubt mixing IR with green would have any effect on how we see the green.I mean, green+invisible=green.If that was true , you would be able to see IR with the bare eye by shinig green light on it, thing which I don't think I've ever heard of. :-/

i think he's talking about frequency summing like as in how yellow lasers work

 

[Switch]

Yea but frequency summing happens in the crystal , not in mid air.