Defined-end beam theory

[ATL Kenobi]

HereÂ’s a thoughtÂ…

What if a very narrow-spectrum coherent light source is collimated and then directed into a beam splitter and subsequently reflected to a focal point three feet away? If the refractive index of the beam splitter and reflector is chosen such that one beam is precisely phase shifted plus 90º and the other shifted minus 90º, would the resultant 180º shift cause the two beams to cancel each other out, resulting in a defined end beam? (Ala a light saber :love .)

If someone has access to an optics lab, IÂ’d be curious to know if thisÂ’d work.

Thanks wackychimp.

ATL Kenobi

 

[xeno]

they won't cancel each other out, it would double the brightness or power

I don't thonk there is something like photons and anti photons


Xeno

 

[YenChih Lin]

Since it's a laser and coherent, the amplitude of the beam will double, if the phase of the beams are the same

 

[donsolo]

The beams would continue after they cross as well, if I'm not mistaken... nice diagram though.

 

[Darth Lars]

I am not sure. Two laser beams of the same frequency, 180° out of phase should cancel eachother out if they were directed straight at eachother or together in the same direction. I am not so sure about two laser beams crossing eachother at a small angle...
Even if it would work in theory, I believe getting any good-looking result would be very difficult. To get to see the beam you would have to put something in it's path that would scatter it which would make the light at the tip to be more or less incoherent anyway.

 

[HAL9000]

Fine, nice theory. But isn't the only problem with a 'laser' lightsaber
that you wouldn't actually be able to see the beam unless you had
alot of very dense smoke or steam in the room?

Surely a constrained active particle beam is what you need?

 

[Eagle]

If anyone can build a lightsaber, this guy can:

http://tesladownunder.com/

 

[DL 44 Blaster]

<div class='quotetop'>(Eagle @ Sep 9 2006, 06:49 PM) [snapback]1316741[/snapback]</div>

If anyone can build a lightsaber, this guy can:

http://tesladownunder.com/
[/b]

:eek It looks like the guy has harnessed "Force lightning"

I'm certain that in OUR lifetime a true lightsaber will be made. Whether it can cut through 12" of steel as in Episode I's beginning I completely doubt, or have any cutting power whatsoever, but I do think a beam of light will be harnessed in a way as to have a solid beam of light at a desired length.

Of course it will be a uber fan of Star Wars who happens to be a uber scientist/physicist/electronic guru he's probably lurking in these very pages..............somewhere...out there...no wait that's a BSG line. :lol

Steve

 

[Darth Lars]

Lots of interesting stuff on that site. What caught my eye was the smoke ring ("ring vortex") generator.
What if a smoke ring generator could produce a stream of rings of some kind of charged smoke or aerosol that are "sucked" back to the emitter using a magnetic or electric field? Then we could have a column of smoke that could be illuminated.

Another thing about lasers is that when laser light is focused into a point in the air, the laser energy would ignite the air at the focal point into a plasma - which emits light. If you move the focal point fast enough, you could possibly create what appears to the human eye as a solid line of light. However, the line would be very thin and I don't think you could make it very bright.
I got the idea from some researchers that are using this phenomenon for three-dimensional computer displays.

 

[ATL Kenobi]

<div class='quotetop'>(Darth Lars @ Sep 9 2006, 04:54 PM) [snapback]1316687[/snapback]</div>

I am not sure. Two laser beams of the same frequency, 180° out of phase should cancel eachother out if they were directed straight at eachother or together in the same direction. I am not so sure about two laser beams crossing eachother at a small angle...
Even if it would work in theory, I believe getting any good-looking result would be very difficult. To get to see the beam you would have to put something in it's path that would scatter it which would make the light at the tip to be more or less incoherent anyway.
[/b]

Darth Lars,

Those are my thoughts eactly - it should work. See Destructive interference . I also agree with you that the optical precision may not be obtainable in this galaxy ,and that actually seeing the beam may be difficult, unless, as HAL9000 pointed out, something is present for the beam to illuminate. But I think this idea might be a starting point.

The "Tesla down under" site is cool. Thanks for the link.

ATL

 

[b26354]

Technology to use a laser to turn air into balls of visible plasma already exists:

http://www.aist.go.jp/aist_e/latest_resear...0/20060210.html

Line up all the dots in a straight line and you've got a lightsaber blade - you could also animate the beam up and down.

Or course fiting it into a graflex might be tricky

 

[Darth Lars]

Two times in this thread, people have repeated what I posted first. :lol

 

[b26354]

<div class='quotetop'>(Darth Lars @ Sep 11 2006, 05:16 AM) [snapback]1317138[/snapback]</div>

Two times in this thread, people have repeated what I posted first. :lol
[/b]

Your link to the Japanese site seems to be broken.