Idea for a "real" Light Saber, can this be done?

How to build a "real" Light Saber?
I want to have an exact live replica of the star wars type light saber.
It's composed by a handle (easy to build a replica)
and a thick laser beam 4-5 feet long that terminates in mid air. This post is how to acheive that.

A powerful collimated laser can pack enough light to show the beam in mid air, but it wont terminate after 4-5 feet, how can this be achieved?

Proposal 1:
One could have a thin metal beam 4 feet long that ends with a mirror. This could bounce back the beam and create the appearance of a light saber.

Pro: Easy to build
Con: Ugly looking when powered off, if metal flex it could send the beam around.

Proposal 2:
One could have a cylinder of plexyglass and coat it with UV reflective paint.
An UV laser at the base will generate a nice light saber glow of light

Pro: Easy and cheap to build
Con: Ugly looking when powered off, heavy


Is it possible to do something to stop the laser beam without using any objects?

Proposal 3:
Nothing is attached to the LS handle, when powered off it can fit in a pocket.
Once powered on a 2 inches think laser beam start to grow from the base of the handle until it reach the desired length and stops there.

How I imagine the above:

With the current standard lens the laser can be collimated to a specific point in the space.
This area have an higher light density, therefore is more visible to the naked eye than the non-collimated beam.

Now imagine to mount the lens on a small sized speaker/woofer.
When you pump a sound into it, the oscillation will collimate the beam to a different position into space. This will appear as a moving bright dot in mid air.
If the frequency is fast enough the human eye will see it as continuous "chunk" of light standing in mid air (instead of a fast moving dot).

Here we are, a mini light saber (the section is extremely small but luminous).

How to make the beam thick?

With other type of lens and a strip of laser diodes one should be able to focus the beam on a 2 inches line. If the lens is oscillated as above one will have a thin but 2 inch wide "chunk" of light, a strip.
If finally the lens is mounted on a ball bearing and rotated fast enough, the strip will become a cylinder, and here you have a "real" light saber replica!

In other words the idea is to collimate a beam to millions of points inside a virtual cylinder fast enough to trick the human eye to think that the entire cylinder is emitting light.

What do you think?
Can you point any technical reason that makes proposal 3 impossible to achieve?

I think the disadvantage will be that beyond the cylinder projected in the air there is still a laser beam visible and it will end somewhere with high enough power to be dangerous. It's still a nice experiment to see if it works.

IMO Your best bet is to construct a clear collapsing segmented tube. (IE a portable radio antenna only clear plexiglass) You build that and have a beam stop in the top end, and you could use the mechanism and motor from an automobile retractable antenna to open and close the LS.

That's how I would do it.

Or you could use balloons.

^^^^:crackup::crackup:^^^^

Jerry

oH NOES!!11
It's this thread all over again.

LOL @ Balloons

I think that Anselm's post will be the best "Star Wars" like Experience. Get some gold cap, I heard thats the best stuff....

Just have some people put on some masks and you feel like your fighting a Real Alien :beer:

ok, I got definitely convinced by the balloons model, but I'll ensure I take enough mushrooms to maximize the effect lol

I do realize I am probably the millionth guy that ask on this forum how to build a light saber,but I got struck with this idea of vibrating optics that could focus the beam so quickly to give the impression of a standing "chunk" of light.

I am ignorant so I don't know why it's impossible, maybe you can help me to figure it out.

After a beam focuses to a point in mid air guess what it does past that point?

It keeps going and spreads outwards more.

So can you see how your idea is flawed now?

Hello Krogith, and Bluefan,
so far the exception you pointed out is the best

When I say I want the beam to stop in mid air, I mean the visible beam:

In my little experiments I noticed that the beam of a low power laser is not visible in a room, but if you focus it, let's say 10CM from the lens, the beam a little before and a little after the focal point becomes more visible, as more light is packed in a smaller place.

I do understand that in my idea expressed in the first post you will have some non collimated light proceeding to the infinite, but my hope was that this light is not dense enough to be seen in mid air, while the area around the focus should be dense enough to be visible.
I don't really aim to stop a laser beam in mid air without any target

What do you think about it?

I like the idea and I can see what you mean. But imagine a laser shaken in fog. The flat rays are not as bright as if you would hold it still and just watch the beam. Not sure why. But if you used a low powered one to be able to make this visible only at its collimated part, and change the focus point very rapidly it'll fade even more. In order to do this you would need a higer powered one but that would be visible better on the far field as well.. So it should be tested but there would be some compromises.

Hi Firsh,
this really make sense, too much power and you see the beam, too few and you don't see the collimated dot.
What about introducing another variable: The size of the beam when it leave the last lens.
I am thinking about a very large lens (i.e. 10 cm) that creates a "cone" of light with a very large base.
The light density there will be pretty small (not visible) but the top can still be very small and therefore visible. /\

Do you think this is this possible?

Yeah I was just thinking about this a few years ago and I always end up with a very large base. It could work, and the far field wouldn't be that dangerous as well. But I don't know what kind of mechanism could do this to the light, what can move the lens so fast? Just a speaker? I don't see that working. But maybe. Depends on how extreme extrusion the collimating lens needs to move the focus point from zero to 1 meter or something like that. Correct me if I'm wrong I'm not too good at physics and lenses.

Dark4ngeL said:

How to build a "real" Light Saber?
I want to have an exact live replica of the star wars type light saber.
It's composed by a handle (easy to build a replica)
and a thick laser beam 4-5 feet long that terminates in mid air. This post is how to acheive that.

Click to expand...

Your physics began to break down right about there

Now go back to the drawing board with the realization that a light saber works with a plasma NOT laser light

Peace,
dave

daguin said:

Your physics began to break down right about there

Now go back to the drawing board with the realization that a light saber works with a plasma NOT laser light

Peace,
dave

Click to expand...

Yeah but where can you buy a handheld plasma "pointer"

Firsh said:

Yeah but where can you buy a handheld plasma "pointer"

Click to expand...

BINGO!

Get that man a kewpie doll :san:

There are a million experiments that you CAN do with laser light. Some of them can kill you or your friends. Why waste time trying to build something that our physics cannot support?

YOU might be the one to advance the physics. However, first, you must master that which exists, my young padawan.

Peace,
dave