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3D laser images in mid air no screen!

zxn474l

zxn474l

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Did anyone watch nation geographical channel last thursday night on "pirotechnics" because at the end of it they interviewed a japaneese company that sucessfully was able to produce muliple 3D images in mid air using no "screen" to prodject these images and is the only country in the world to be able to get a laser to focus it's focal point in mid air without the "beam coninuing past it's focal point! AMAZING! In theory using this technology you could then make a real "light saber!" STAR WARS is here my friends!
 





zxn474l said:
Did anyone watch nation geographical channel last thursday night on "pirotechnics" because at the end of it they interviewed a japaneese company that sucessfully was able to produce muliple 3D images in mid air using no "screen" to prodject these images and is the only country in the world to be able to get a laser to focus it's focal point in mid air without the "beam coninuing past it's focal point! AMAZING! In theory using this technology you could then make a real "light saber!" STAR WARS is here my friends!
Click to expand...

This is a very simple trick that has been around for a long time. Because of the high peak powers of Q-Switched lasers, they can produce a plasma in the air due to the concentrated local heating. This plasma will disturb the beams propagation causing it to scatter. All this company did was to put a setup with a XYZ scanning system in front of a Q-Switched laser with a high repetition rate. The XY will position the angle of the beam while the Z axis consists of a fast moving lens to change the focal point of the laser.

This kind of setup is not practical for anything besides demonstrating it can be done. It is far to dangerous and costly to do this on any sort of consumer level product. The scattered light alone is enough to blind anyone directly viewing the system who is not wearing protective eyewear.

We have done this experiment at work with the pulsed Continuum PV mode locked system we have. It has a high enough peak power that it can create a plasma without any focusing. For this reason, most high energy beams are only used within a vacuum or a ultrapure gas such as dry nitrogen.
 
Wouldn't "eye-safe"wavelengths be the best choice for this? Or are the powers just so high that it will burn anything no matter what?
 
As far as I know, no visible wavelength is "eye safe".

And also, most of the light is turned into plasma. Plasma doesn't have a wavelength, does it?
 
to randomlugia:

Plasma is the 4th state of matter, so it can't have a wavelength; but, one of its caracteristic is that atoms, because of their very excited state, will release photons; and I think that the atoms excitement state can influence the photon's wavelength.

But that I'm not sure.


Random gun
:gun:
 
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At these powers, the energies will burn your cornea before then even reach the retina. There are eye safe wavelengths, however they are not available in high enough powers.

In any gas laser, you have a plasma, it is emitting photons which you see as a color. Depending on the atomic transitions of the gas, it emits different wavelengths.
 
randomlugia said:
As far as I know, no visible wavelength is "eye safe".

And also, most of the light is turned into plasma. Plasma doesn't have a wavelength, does it?
Click to expand...

It's not necessary for the laser to be visible in order to create plasma points in the air.. in fact, I think such a system would work best with invisible lasers.
 
this really sounds amazing, but however there's a point I don't get.

For a laser to create plamsa in the air the air must absorb the laser energy, and I thought gases weren't absorbing the light!

Do they?

Yours,
Albert
 
If there is enough power density, then they have little choice but to absorb at least some of the energy.
 
but even if air absorb a very very little amount of light, then how comes we for example can see the stars? Even if there are very few gases on the space there are some, and if they are really absorbing light, then how comes we can see them?

I'm really astonished about this.

Yours,
Albert
 
To be honest, absorbed isn't really the right word. If you have a powerful enough laser, and you focus all of it's power to a point, then at that point the power density will often be enough to actually ionize the air and cause a light discharge accompanied by a snap of noise.. Lightning does the same thing, this is why it emits light and thunder, but it is caused by electrical energy ionizing the air molecules instead of photons in the case of lasers.. you could say it's photonic lightning in a way.
 
I have observed my SSY-1 1064 nM Q switched laser make momentary plasma bursts using a 3" FL lens. Yes it damaged the lens but it was neet to actually see.

Mike
 
I'll bet.. I've never seen it with my own eyes, and it would be pretty awesome to do it with one of my lasers, but I don't have anywhere near that much power..:(
 
As asked earlier, yes, air does absorb some light. This is why you would be able to see many more stars in space then on the ground. While this amount is very very small, when you have enough energy density at a single point, it will reach the breakdown point of air.

Another good example of why it happens, why do you think the air is so hot on a sunny day. Part of it is from the ground absorbing the light and making heat, but another bit of it is from the air absorbing the light.
 
Laser_Ben said:
As asked earlier, yes, air does absorb some light. This is why you would be able to see many more stars in space then on the ground. While this amount is very very small, when you have enough energy density at a single point, it will reach the breakdown point of air.

Another good example of why it happens, why do you think the air is so hot on a sunny day. Part of it is from the ground absorbing the light and making heat, but another bit of it is from the air absorbing the light.
Click to expand...

This and the thunder explanation helped me a lot :o Rep for both!
 
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