Tractor beams come to life

September 8, 2010 By Mike Lucibella, ISNS
The tractor beam in action suspends a small particle over an optics table. Credit: Courtesy of the Australian National University

Tractor beams, energy rays that can move objects, are a science fiction mainstay. But now they are becoming a reality -- at least for moving very tiny objects.

Researchers from the Australian National University have announced that they have built a device that can move small particles a meter and a half using only the power of light.

Physicists have been able to manipulate tiny particles over miniscule distances by using lasers for years. Optical tweezers that can move particles a few millimeters are common.

Andrei Rhode, a researcher involved with the project, said that existing are able to move particles the size of a bacterium a few millimeters in a liquid. Their new technique can move objects one hundred times that size over a distance of a meter or more.

The device works by shining a hollow around tiny glass particles. The air surrounding the particle heats up, while the dark center of the beam stays cool. When the particle starts to drift out of the middle and into the bright laser beam, the force of heated air molecules bouncing around and hitting the particle's surface is enough to nudge it back to the center.

A small amount of light also seeps into the darker middle part of the beam, heating the air on one side of the particle and pushing it along the length of the laser beam. If another such laser is lined up on the opposite side of the beam, the speed and direction the particle moves can be easily manipulated by changing the brightness of the beams.

Rhode said that their technique could likely work over even longer distances than they tested.

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"With the particles and the laser we use, I would guess up to 10 meters in air should not be a problem. The max distance we had was 1.5 meters, which was limited by the size of the optical table in the lab," Rhode said.

Because this technique needs heated gas to push the particles around, it can't work in the vacuum of outer space like the tractor beams in . But on Earth there are many possible applications for the technology. The meter-long distances that the research team was able to move the particles could open up new avenues for tweezers in the transport of dangerous substances and microbes, and for sample taking and biomedical research.

"There is the possibility that one could use the hollow spheres as a means of chemical delivery agents, or microscopic containers of some kind, but some more work would need to be done here just to check what happens inside the spheres, in terms of sample heating," said David McGloin, a physicist at the University of Dundee in the U.K not connected with the Australian team.

Explore further: Integrated optical trap holds particles for on-chip analysis

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5 / 5 (6) Sep 08, 2010
Tractor beam? Isn't it pushing the particle, rather than pulling? That may seem like a minor distinction, but i would have been infinitely more impressed with a single laser attracting a particle rather than propelling it.
5 / 5 (2) Sep 08, 2010
Correct, this is a pressor beam rather than a tractor beam. Doc Smith knew proper usage.
5 / 5 (1) Sep 08, 2010
If another such laser is lined up on the opposite side...

I would be more impressed if even a single laser pushed it. You could always launch some kind of mirror on the opposite end. This tech is more of a moving net than a tractor.
not rated yet Sep 08, 2010
One word: Lightsaber!

Not the real thing(?) but probably a nice fake, using the technique to hold particles, a gas or something prisonner in the hollow laser beam.

Would that work?
not rated yet Sep 08, 2010
not rated yet Sep 08, 2010
Actually as this in air the laser would disperse creating a cone of hot air. By increasing the dispersion rate of the laser over time the cone would get shorter and 'pull' the glass bead towards the source of the beam.

Or you could have a secondary laser that crosses the first beam and so you can move the bead as you like, I believe this was stated in the article.
not rated yet Sep 08, 2010
This is pretty cool. I wonder what variations could be made?

Perhaps using the laser in heavier inert gases with higher beam strength could increase the speed of transportation to make it viable in the distant future.

I wonder what could be the affect of lasers on the matter being transported, or if special materials containers might get better transportation results.

Great work Aussie mates! I wish my work was so cool. :)
not rated yet Sep 08, 2010
The heading "Tractor beams to come" is the heading but the article does describe what is actually happening and yes it is not a tractor beam and nothing like it.

But it is very useful and may well be incorporated amongst other devices in nuclear fusion or other cutting edge science.
not rated yet Sep 09, 2010
Instead of light tweezers this is more like light tongs.
not rated yet Sep 09, 2010
I know its been pointed out already! But a tractor beam pulls not pushes.
not rated yet Sep 09, 2010
Along with pressure chamber centrifugal processes spinning and weaving vapor into thinfilms or materials such as diamonds and exotic ceramics from simple gasses, optical tweezers and magnetic fields becomes a simple possibility.
not rated yet Sep 10, 2010
Teleportation. Cloaking. The entire spectrum of the moustache sciences.
1 / 5 (1) Sep 12, 2010
They are doing this on an object in air.
Do it in a vacuum and then get back to me.

""When the particle starts to drift out of the middle and into the bright laser beam, the force of heated air molecules bouncing around and hitting the particle's surface is enough to nudge it back to the center.""

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