Physicists create real life tractor beam using lasers
Invention brings us one step closer to realizing 'Star Trek'-like technology.
Wed, Oct 24, 2012 at 01:50 AM
"Star Trek" has inspired countless scientists over the years to dedicate their lives to developing space-age technology. Perhaps it's no surprise that so many breakthroughs today seem as though they come straight out of a "Star Trek" episode. Case in point: scientists from New York University have invented the world's first tractor beam prototype using Bessel beams, reports Physorg.com.
Bessel beams are basically types of lasers that project light in concentric circles around a single dot. They have the unusual property of being non-diffractive. In other words, they do not "spread out" after being focused down to a small spot, unlike most light beams. One result of this is that they are also self-healing, in the sense that they can reform at another point down the beam axis, even if the beam is partially obstructed.
Scientists realized that this self-healing property could be manipulated to pull an object back toward the beam source by firing the beam so that the object partially obstructs its path. If done precisely, this causes the beam to push on the backside of the object as it reforms, thus producing a tractor beam effect.
The concept sounds simple enough, but it's remarkably difficult to achieve in practice. Researchers David Ruffner and David Grier tried and failed during their first attempts using a single Bessel beam. Their stroke of genius came only after a process of trial and error. They then decided to try and use two beams instead, with a lens that bent the beams slightly to cause them to overlap. This created a strobe effect, which was more powerful than the single beam alone. Long story short: it worked. The object got pulled backwards.
Though the tractor beam they created looks as though it pulls an object toward its source, the reality is that the beam is actually "looping around" the object and pushing it from behind. For all intents and purposes, though, this is an honest-to-goodness, "Star Trek"-esque tractor beam.
The only downside? So far the beam only works on small particles. Ruffner and Grier were able to successfully pull a 30-micrometer silica sphere suspended in water towards a laser source. Anything much bigger would likely be destroyed by the amount of energy necessary to pull it. But this is just the first step. The researchers are optimistic that as the method gets fine tuned, it could be adjusted to manage larger moving objects.
Between this technology and recent advances in quantum teleportation, pretty soon all we'll have left to do is build a real-life Starship Enterprise. (Actually, this is already being done too. Yes, really.)
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